* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann
OMAP4 introduces a Hardware Spinlock device, which provides hardware
assistance for synchronization and mutual exclusion between heterogeneous
processors and those not operating under a single, shared operating system
(e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
The intention of this hardware device is to allow remote processors,
that have no alternative mechanism to accomplish synchronization and mutual
exclusion operations, to share resources (such as memory and/or any other
hardware resource).
This patchset adds hwspinlock framework that makes it possible
for drivers to use those hwspinlock devices and stay platform-independent.
Currently there are two users for this hwspinlock interface:
1. Inter-processor communications: on OMAP4, cpu-intensive multimedia
tasks are offloaded by the host to the remote M3 and/or C64x+ slave
processors.
To achieve fast message-based communications, a minimal kernel support
is needed to deliver messages arriving from a remote processor to the
appropriate user process.
This communication is based on a simple data structure that is shared between
the remote processors, and access to it is synchronized using the hwspinlock
module (remote processor directly places new messages in this shared data
structure).
2. On some OMAP4 boards, the I2C bus is shared between the A9 and the M3,
and the hwspinlock is used to synchronize access to it.
While (2) can get away with an omap-specific hwspinlock implementation,
(1) is by no means omap-specific, and a common hwspinlock interface is
needed to keep it generic, in hopes that it will be useful for other
platforms as well.
Changes v2->v3:
- Remove the timeout-less _lock API variant (Tony)
- s/state->io_base/io_base/ (Ionut)
- Remove the "generic" wording (David)
- s/hwspinlock_/hwspin_lock_/ (Mugdha)
- Use MAX_SCHEDULE_TIMEOUT to indicate no timeout (Mugdha)
- Be more verbose on egregious API misuse (Olof)
- locking API misuse is BUG_ON material (Russell)
Note: Russell also suggested compiling out NULL checks on ARM.
I've posted an initial proposal for this (see
https://lkml.org/lkml/2010/11/29/96), which I'm going to resubmit
separately. If accepted, I'll adopt hwspinlocks to use it.
Patches are tested against linux-omap-2.6 master, which is 2.6.37-rc4 plus
omap material. All, but the third (the hwmod omap patch), apply on top of
mainline 2.6.37-rc4 as well
Changes v1->v2:
- Convert to a generic interface (Tony)
- API should silently succeed if framework isn't built (Greg)
- Don't use ERR_PTR pattern (Grant)
- Use tristate, fix and extend commentary (Kevin)
- Provide API flexibility regarding irq handling (Arnd, Grant)
Note: after reviewing OMAP's L4 access times, and comparing them with
external memory latencies, I can say that there is no notable difference.
Because of that, we can safely treat the hwspinlock like we do
with regular spinlocks: preemption should be disabled, but whether
to disable interrupts or not is up to the caller.
So despite the TRM's recommendation to always disable local interrupts
when taking an OMAP Hardware Spinlock, I have decided to allow callers
not to do that (by providing the full extent of hwspin_lock(),
hwspin_lock_irq() and hwspin_lock_irqsave() API).
Just like regular spinlocks, it's up to the callers to decide whether
interrupts should be disabled or not.
Sleeping, btw, is still prohibited of course.
Contributions:
Previous versions of an omap-specific hwspinlock driver circulated in
linux-omap several times, and received substantial attention and contribution
from many developers (see [1][2][3][4][5][6]):
Simon Que did the initial implementation and pushed several iterations
Benoit Cousson provided extensive review, help, improvements and hwmod support
Hari Kanigeri helped out when Simon was away
Sanjeev Premi, Santosh Shilimkar and Nishanth Menon did lots of review
I'd like to thank Benoit Cousson, Steve Krueger, Hari Kanigeri,
Nourredine Hamoudi and Richard Woodruff for useful discussions about
the OMAP Spinlock requirements and use-cases.
Relevant linux-omap threads:
[1] http://thread.gmane.org/gmane.linux.ports.arm.omap/38755
[2] http://thread.gmane.org/gmane.linux.ports.arm.omap/38917
[3] http://thread.gmane.org/gmane.linux.ports.arm.omap/39187
[4] http://thread.gmane.org/gmane.linux.ports.arm.omap/39365
[5] http://thread.gmane.org/gmane.linux.ports.arm.omap/39815
[6] http://thread.gmane.org/gmane.linux.ports.arm.omap/40901
Benoit Cousson (1):
OMAP4: hwmod data: Add hwspinlock
Ohad Ben-Cohen (1):
drivers: hwspinlock: add framework
Simon Que (2):
drivers: hwspinlock: add OMAP implementation
omap: add hwspinlock device
Documentation/hwspinlock.txt | 299 +++++++++++++++
arch/arm/mach-omap2/Makefile | 1 +
arch/arm/mach-omap2/hwspinlock.c | 63 ++++
arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/hwspinlock/Kconfig | 22 ++
drivers/hwspinlock/Makefile | 6 +
drivers/hwspinlock/hwspinlock.h | 61 +++
drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++
include/linux/hwspinlock.h | 298 +++++++++++++++
12 files changed, 1605 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwspinlock.txt
create mode 100644 arch/arm/mach-omap2/hwspinlock.c
create mode 100644 drivers/hwspinlock/Kconfig
create mode 100644 drivers/hwspinlock/Makefile
create mode 100644 drivers/hwspinlock/hwspinlock.h
create mode 100644 drivers/hwspinlock/hwspinlock_core.c
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
create mode 100644 include/linux/hwspinlock.h
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann
OMAP4 introduces a Hardware Spinlock device, which provides hardware
assistance for synchronization and mutual exclusion between heterogeneous
processors and those not operating under a single, shared operating system
(e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
The intention of this hardware device is to allow remote processors,
that have no alternative mechanism to accomplish synchronization and mutual
exclusion operations, to share resources (such as memory and/or any other
hardware resource).
This patchset adds hwspinlock framework that makes it possible
for drivers to use those hwspinlock devices and stay platform-independent.
Currently there are two users for this hwspinlock interface:
1. Inter-processor communications: on OMAP4, cpu-intensive multimedia
tasks are offloaded by the host to the remote M3 and/or C64x+ slave
processors.
To achieve fast message-based communications, a minimal kernel support
is needed to deliver messages arriving from a remote processor to the
appropriate user process.
This communication is based on a simple data structure that is shared between
the remote processors, and access to it is synchronized using the hwspinlock
module (remote processor directly places new messages in this shared data
structure).
2. On some OMAP4 boards, the I2C bus is shared between the A9 and the M3,
and the hwspinlock is used to synchronize access to it.
While (2) can get away with an omap-specific hwspinlock implementation,
(1) is by no means omap-specific, and a common hwspinlock interface is
needed to keep it generic, in hopes that it will be useful for other
platforms as well.
Changes v2->v3:
- Remove the timeout-less _lock API variant (Tony)
- s/state->io_base/io_base/ (Ionut)
- Remove the "generic" wording (David)
- s/hwspinlock_/hwspin_lock_/ (Mugdha)
- Use MAX_SCHEDULE_TIMEOUT to indicate no timeout (Mugdha)
- Be more verbose on egregious API misuse (Olof)
- locking API misuse is BUG_ON material (Russell)
Note: Russell also suggested compiling out NULL checks on ARM.
I've posted an initial proposal for this (see
https://lkml.org/lkml/2010/11/29/96), which I'm going to resubmit
separately. If accepted, I'll adopt hwspinlocks to use it.
Patches are tested against linux-omap-2.6 master, which is 2.6.37-rc4 plus
omap material. All, but the third (the hwmod omap patch), apply on top of
mainline 2.6.37-rc4 as well
Changes v1->v2:
- Convert to a generic interface (Tony)
- API should silently succeed if framework isn't built (Greg)
- Don't use ERR_PTR pattern (Grant)
- Use tristate, fix and extend commentary (Kevin)
- Provide API flexibility regarding irq handling (Arnd, Grant)
Note: after reviewing OMAP's L4 access times, and comparing them with
external memory latencies, I can say that there is no notable difference.
Because of that, we can safely treat the hwspinlock like we do
with regular spinlocks: preemption should be disabled, but whether
to disable interrupts or not is up to the caller.
So despite the TRM's recommendation to always disable local interrupts
when taking an OMAP Hardware Spinlock, I have decided to allow callers
not to do that (by providing the full extent of hwspin_lock(),
hwspin_lock_irq() and hwspin_lock_irqsave() API).
Just like regular spinlocks, it's up to the callers to decide whether
interrupts should be disabled or not.
Sleeping, btw, is still prohibited of course.
Contributions:
Previous versions of an omap-specific hwspinlock driver circulated in
linux-omap several times, and received substantial attention and contribution
from many developers (see [1][2][3][4][5][6]):
Simon Que did the initial implementation and pushed several iterations
Benoit Cousson provided extensive review, help, improvements and hwmod support
Hari Kanigeri helped out when Simon was away
Sanjeev Premi, Santosh Shilimkar and Nishanth Menon did lots of review
I'd like to thank Benoit Cousson, Steve Krueger, Hari Kanigeri,
Nourredine Hamoudi and Richard Woodruff for useful discussions about
the OMAP Spinlock requirements and use-cases.
Relevant linux-omap threads:
[1] http://thread.gmane.org/gmane.linux.ports.arm.omap/38755
[2] http://thread.gmane.org/gmane.linux.ports.arm.omap/38917
[3] http://thread.gmane.org/gmane.linux.ports.arm.omap/39187
[4] http://thread.gmane.org/gmane.linux.ports.arm.omap/39365
[5] http://thread.gmane.org/gmane.linux.ports.arm.omap/39815
[6] http://thread.gmane.org/gmane.linux.ports.arm.omap/40901
Benoit Cousson (1):
OMAP4: hwmod data: Add hwspinlock
Ohad Ben-Cohen (1):
drivers: hwspinlock: add framework
Simon Que (2):
drivers: hwspinlock: add OMAP implementation
omap: add hwspinlock device
Documentation/hwspinlock.txt | 299 +++++++++++++++
arch/arm/mach-omap2/Makefile | 1 +
arch/arm/mach-omap2/hwspinlock.c | 63 ++++
arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/hwspinlock/Kconfig | 22 ++
drivers/hwspinlock/Makefile | 6 +
drivers/hwspinlock/hwspinlock.h | 61 +++
drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++
include/linux/hwspinlock.h | 298 +++++++++++++++
12 files changed, 1605 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwspinlock.txt
create mode 100644 arch/arm/mach-omap2/hwspinlock.c
create mode 100644 drivers/hwspinlock/Kconfig
create mode 100644 drivers/hwspinlock/Makefile
create mode 100644 drivers/hwspinlock/hwspinlock.h
create mode 100644 drivers/hwspinlock/hwspinlock_core.c
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
create mode 100644 include/linux/hwspinlock.h
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-arm-kernel
OMAP4 introduces a Hardware Spinlock device, which provides hardware
assistance for synchronization and mutual exclusion between heterogeneous
processors and those not operating under a single, shared operating system
(e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
The intention of this hardware device is to allow remote processors,
that have no alternative mechanism to accomplish synchronization and mutual
exclusion operations, to share resources (such as memory and/or any other
hardware resource).
This patchset adds hwspinlock framework that makes it possible
for drivers to use those hwspinlock devices and stay platform-independent.
Currently there are two users for this hwspinlock interface:
1. Inter-processor communications: on OMAP4, cpu-intensive multimedia
tasks are offloaded by the host to the remote M3 and/or C64x+ slave
processors.
To achieve fast message-based communications, a minimal kernel support
is needed to deliver messages arriving from a remote processor to the
appropriate user process.
This communication is based on a simple data structure that is shared between
the remote processors, and access to it is synchronized using the hwspinlock
module (remote processor directly places new messages in this shared data
structure).
2. On some OMAP4 boards, the I2C bus is shared between the A9 and the M3,
and the hwspinlock is used to synchronize access to it.
While (2) can get away with an omap-specific hwspinlock implementation,
(1) is by no means omap-specific, and a common hwspinlock interface is
needed to keep it generic, in hopes that it will be useful for other
platforms as well.
Changes v2->v3:
- Remove the timeout-less _lock API variant (Tony)
- s/state->io_base/io_base/ (Ionut)
- Remove the "generic" wording (David)
- s/hwspinlock_/hwspin_lock_/ (Mugdha)
- Use MAX_SCHEDULE_TIMEOUT to indicate no timeout (Mugdha)
- Be more verbose on egregious API misuse (Olof)
- locking API misuse is BUG_ON material (Russell)
Note: Russell also suggested compiling out NULL checks on ARM.
I've posted an initial proposal for this (see
https://lkml.org/lkml/2010/11/29/96), which I'm going to resubmit
separately. If accepted, I'll adopt hwspinlocks to use it.
Patches are tested against linux-omap-2.6 master, which is 2.6.37-rc4 plus
omap material. All, but the third (the hwmod omap patch), apply on top of
mainline 2.6.37-rc4 as well
Changes v1->v2:
- Convert to a generic interface (Tony)
- API should silently succeed if framework isn't built (Greg)
- Don't use ERR_PTR pattern (Grant)
- Use tristate, fix and extend commentary (Kevin)
- Provide API flexibility regarding irq handling (Arnd, Grant)
Note: after reviewing OMAP's L4 access times, and comparing them with
external memory latencies, I can say that there is no notable difference.
Because of that, we can safely treat the hwspinlock like we do
with regular spinlocks: preemption should be disabled, but whether
to disable interrupts or not is up to the caller.
So despite the TRM's recommendation to always disable local interrupts
when taking an OMAP Hardware Spinlock, I have decided to allow callers
not to do that (by providing the full extent of hwspin_lock(),
hwspin_lock_irq() and hwspin_lock_irqsave() API).
Just like regular spinlocks, it's up to the callers to decide whether
interrupts should be disabled or not.
Sleeping, btw, is still prohibited of course.
Contributions:
Previous versions of an omap-specific hwspinlock driver circulated in
linux-omap several times, and received substantial attention and contribution
from many developers (see [1][2][3][4][5][6]):
Simon Que did the initial implementation and pushed several iterations
Benoit Cousson provided extensive review, help, improvements and hwmod support
Hari Kanigeri helped out when Simon was away
Sanjeev Premi, Santosh Shilimkar and Nishanth Menon did lots of review
I'd like to thank Benoit Cousson, Steve Krueger, Hari Kanigeri,
Nourredine Hamoudi and Richard Woodruff for useful discussions about
the OMAP Spinlock requirements and use-cases.
Relevant linux-omap threads:
[1] http://thread.gmane.org/gmane.linux.ports.arm.omap/38755
[2] http://thread.gmane.org/gmane.linux.ports.arm.omap/38917
[3] http://thread.gmane.org/gmane.linux.ports.arm.omap/39187
[4] http://thread.gmane.org/gmane.linux.ports.arm.omap/39365
[5] http://thread.gmane.org/gmane.linux.ports.arm.omap/39815
[6] http://thread.gmane.org/gmane.linux.ports.arm.omap/40901
Benoit Cousson (1):
OMAP4: hwmod data: Add hwspinlock
Ohad Ben-Cohen (1):
drivers: hwspinlock: add framework
Simon Que (2):
drivers: hwspinlock: add OMAP implementation
omap: add hwspinlock device
Documentation/hwspinlock.txt | 299 +++++++++++++++
arch/arm/mach-omap2/Makefile | 1 +
arch/arm/mach-omap2/hwspinlock.c | 63 ++++
arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/hwspinlock/Kconfig | 22 ++
drivers/hwspinlock/Makefile | 6 +
drivers/hwspinlock/hwspinlock.h | 61 +++
drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++
include/linux/hwspinlock.h | 298 +++++++++++++++
12 files changed, 1605 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwspinlock.txt
create mode 100644 arch/arm/mach-omap2/hwspinlock.c
create mode 100644 drivers/hwspinlock/Kconfig
create mode 100644 drivers/hwspinlock/Makefile
create mode 100644 drivers/hwspinlock/hwspinlock.h
create mode 100644 drivers/hwspinlock/hwspinlock_core.c
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
create mode 100644 include/linux/hwspinlock.h
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 1/4] drivers: hwspinlock: add framework
2010-12-03 23:50 ` Ohad Ben-Cohen
(?)
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann
Add a platform-independent hwspinlock framework.
Hardware spinlock devices are needed, e.g., in order to access data
that is shared between remote processors, that otherwise have no
alternative mechanism to accomplish synchronization and mutual exclusion
operations.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Hari Kanigeri <h-kanigeri2@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
Documentation/hwspinlock.txt | 299 ++++++++++++++++++
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/hwspinlock/Kconfig | 13 +
drivers/hwspinlock/Makefile | 5 +
drivers/hwspinlock/hwspinlock.h | 61 ++++
drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++++++++
include/linux/hwspinlock.h | 298 ++++++++++++++++++
8 files changed, 1236 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwspinlock.txt
create mode 100644 drivers/hwspinlock/Kconfig
create mode 100644 drivers/hwspinlock/Makefile
create mode 100644 drivers/hwspinlock/hwspinlock.h
create mode 100644 drivers/hwspinlock/hwspinlock_core.c
create mode 100644 include/linux/hwspinlock.h
diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
new file mode 100644
index 0000000..65324ce
--- /dev/null
+++ b/Documentation/hwspinlock.txt
@@ -0,0 +1,299 @@
+Hardware Spinlock Framework
+
+1. Introduction
+
+Hardware spinlock modules provide hardware assistance for synchronization
+and mutual exclusion between heterogeneous processors and those not operating
+under a single, shared operating system.
+
+For example, OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP,
+each of which is running a different Operating System (the master, A9,
+is usually running Linux and the slave processors, the M3 and the DSP,
+are running some flavor of RTOS).
+
+A generic hwspinlock framework allows platform-independent drivers to use
+the hwspinlock device in order to access data structures that are shared
+between remote processors, that otherwise have no alternative mechanism
+to accomplish synchronization and mutual exclusion operations.
+
+This is necessary, for example, for Inter-processor communications:
+on OMAP4, cpu-intensive multimedia tasks are offloaded by the host to the
+remote M3 and/or C64x+ slave processors (by an IPC subsystem called Syslink).
+
+To achieve fast message-based communications, a minimal kernel support
+is needed to deliver messages arriving from a remote processor to the
+appropriate user process.
+
+This communication is based on simple data structures that is shared between
+the remote processors, and access to it is synchronized using the hwspinlock
+module (remote processor directly places new messages in this shared data
+structure).
+
+A common hwspinlock interface makes it possible to have generic, platform-
+independent, drivers.
+
+2. User API
+
+ struct hwspinlock *hwspin_lock_request(void);
+ - dynamically assign an hwspinlock and return its address, or NULL
+ in case an unused hwspinlock isn't available. Users of this
+ API will usually want to communicate the lock's id to the remote core
+ before it can be used to achieve synchronization.
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
+ - assign a specific hwspinlock id and return its address, or NULL
+ if that hwspinlock is already in use. Usually board code will
+ be calling this function in order to reserve specific hwspinlock
+ ids for predefined purposes.
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ int hwspin_lock_free(struct hwspinlock *hwlock);
+ - free a previously-assigned hwspinlock; returns 0 on success, or an
+ appropriate error code on failure (e.g. -EINVAL if the hwspinlock
+ is already free).
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ int hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned long timeout);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption is disabled so
+ the caller must not sleep, and is advised to release the hwspinlock as
+ soon as possible, in order to minimize remote cores polling on the
+ hardware interconnect.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, unsigned long timeout);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption and the local
+ interrupts are disabled, so the caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock, unsigned long to,
+ unsigned long *flags);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption is disabled,
+ local interrupts are disabled and their previous state is saved at the
+ given flags placeholder. The caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_trylock(struct hwspinlock *hwlock);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption is disabled so
+ caller must not sleep, and is advised to release the hwspinlock as soon as
+ possible, in order to minimize remote cores polling on the hardware
+ interconnect.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ int hwspin_trylock_irq(struct hwspinlock *hwlock);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption and the local
+ interrupts are disabled so caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption is disabled,
+ the local interrupts are disabled and their previous state is saved
+ at the given flags placeholder. The caller must not sleep, and is advised
+ to release the hwspinlock as soon as possible.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ void hwspin_unlock(struct hwspinlock *hwlock);
+ - unlock a previously-locked hwspinlock. Always succeed, and can be called
+ from any context (the function never sleeps). Note: code should _never_
+ unlock an hwspinlock which is already unlocked (there is no protection
+ against this).
+
+ void hwspin_unlock_irq(struct hwspinlock *hwlock);
+ - unlock a previously-locked hwspinlock and enable local interrupts.
+ The caller should _never_ unlock an hwspinlock which is already unlocked.
+ Doing so is considered a bug (there is no protection against this).
+ Upon a successful return from this function, preemption and local
+ interrupts are enabled. This function will never sleep.
+
+ void
+ hwspin_unlock_irqrestore(struct hwspinlock *hwlock, unsigned long *flags);
+ - unlock a previously-locked hwspinlock.
+ The caller should _never_ unlock an hwspinlock which is already unlocked.
+ Doing so is considered a bug (there is no protection against this).
+ Upon a successful return from this function, preemption is reenabled,
+ and the state of the local interrupts is restored to the state saved at
+ the given flags. This function will never sleep.
+
+ int hwspin_lock_get_id(struct hwspinlock *hwlock);
+ - retrieve id number of a given hwspinlock. This is needed when an
+ hwspinlock is dynamically assigned: before it can be used to achieve
+ mutual exclusion with a remote cpu, the id number should be communicated
+ to the remote task with which we want to synchronize.
+ Returns the hwspinlock id number, or -EINVAL if hwlock is null.
+
+3. Typical usage
+
+#include <linux/hwspinlock.h>
+#include <linux/err.h>
+
+int hwspinlock_example1(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ /* dynamically assign a hwspinlock */
+ hwlock = hwspin_lock_request();
+ if (!hwlock)
+ ...
+
+ id = hwspin_lock_get_id(hwlock);
+ /* probably need to communicate id to a remote processor now */
+
+ /* take the lock, spin for 1 sec if it's already taken */
+ ret = hwspin_lock_timeout(hwlock, msecs_to_jiffies(1000));
+ if (ret)
+ ...
+
+ /*
+ * we took the lock, do our thing now, but do NOT sleep
+ */
+
+ /* release the lock */
+ hwspin_unlock(hwlock);
+
+ /* free the lock */
+ ret = hwspin_lock_free(hwlock);
+ if (ret)
+ ...
+
+ return ret;
+}
+
+int hwspinlock_example2(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ /*
+ * assign a specific hwspinlock id - this should be called early
+ * by board init code.
+ */
+ hwlock = hwspin_lock_request_specific(PREDEFINED_LOCK_ID);
+ if (!hwlock)
+ ...
+
+ /* try to take it, but don't spin on it */
+ ret = hwspin_trylock(hwlock);
+ if (!ret) {
+ pr_info("lock is already taken\n");
+ return -EBUSY;
+ }
+
+ /*
+ * we took the lock, do our thing now, but do NOT sleep
+ */
+
+ /* release the lock */
+ hwspin_unlock(hwlock);
+
+ /* free the lock */
+ ret = hwspin_lock_free(hwlock);
+ if (ret)
+ ...
+
+ return ret;
+}
+
+
+4. API for implementors
+
+ int hwspin_lock_register(struct hwspinlock *hwlock);
+ - to be called from the underlying platform-specific implementation, in
+ order to register a new hwspinlock instance. Can be called from an atomic
+ context (this function will not sleep) but not from within interrupt
+ context. Returns 0 on success, or appropriate error code on failure.
+
+ struct hwspinlock *hwspin_lock_unregister(unsigned int id);
+ - to be called from the underlying vendor-specific implementation, in order
+ to unregister an existing (and unused) hwspinlock instance.
+ Can be called from an atomic context (will not sleep) but not from
+ within interrupt context.
+ Returns the address of hwspinlock on success, or NULL on error (e.g.
+ if the hwspinlock is sill in use).
+
+5. struct hwspinlock
+
+This struct represents an hwspinlock instance. It is registered by the
+underlying hwspinlock implementation using the hwspin_lock_register() API.
+
+/**
+ * struct hwspinlock - vendor-specific hwspinlock implementation
+ *
+ * @dev: underlying device, will be used with runtime PM api
+ * @ops: vendor-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ */
+struct hwspinlock {
+ struct device *dev;
+ const struct hwspinlock_ops *ops;
+ int id;
+ spinlock_t lock;
+ struct module *owner;
+};
+
+The underlying implementation is responsible to assign the dev, ops, id and
+owner members. The lock member, OTOH, is initialized and used by the hwspinlock
+core.
+
+6. Implementation callbacks
+
+There are three possible callbacks defined in 'struct hwspinlock_ops':
+
+struct hwspinlock_ops {
+ int (*trylock)(struct hwspinlock *lock);
+ void (*unlock)(struct hwspinlock *lock);
+ void (*relax)(struct hwspinlock *lock);
+};
+
+The first two callbacks are mandatory:
+
+The ->trylock() callback should make a single attempt to take the lock, and
+return 0 on failure and 1 on success. This callback may _not_ sleep.
+
+The ->unlock() callback releases the lock. It always succeed, and it, too,
+may _not_ sleep.
+
+The ->relax() callback is optional. It is called by hwspinlock core while
+spinning on a lock, and can be used by the underlying implementation to force
+a delay between two successive invocations of ->trylock(). It may _not_ sleep.
diff --git a/drivers/Kconfig b/drivers/Kconfig
index a2b902f..c0e2eab 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -111,4 +111,6 @@ source "drivers/xen/Kconfig"
source "drivers/staging/Kconfig"
source "drivers/platform/Kconfig"
+
+source "drivers/hwspinlock/Kconfig"
endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index cafb881..bb0c472 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -115,3 +115,4 @@ obj-$(CONFIG_VLYNQ) += vlynq/
obj-$(CONFIG_STAGING) += staging/
obj-y += platform/
obj-y += ieee802154/
+obj-$(CONFIG_HWSPINLOCK) += hwspinlock/
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
new file mode 100644
index 0000000..9dd8db4
--- /dev/null
+++ b/drivers/hwspinlock/Kconfig
@@ -0,0 +1,13 @@
+#
+# Generic HWSPINLOCK framework
+#
+
+config HWSPINLOCK
+ tristate "Generic Hardware Spinlock framework"
+ help
+ Say y here to support the generic hardware spinlock framework.
+ You only need to enable this if you have hardware spinlock module
+ on your system (usually only relevant if your system has remote slave
+ coprocessors).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
new file mode 100644
index 0000000..b9d2b9f
--- /dev/null
+++ b/drivers/hwspinlock/Makefile
@@ -0,0 +1,5 @@
+#
+# Generic Hardware Spinlock framework
+#
+
+obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
diff --git a/drivers/hwspinlock/hwspinlock.h b/drivers/hwspinlock/hwspinlock.h
new file mode 100644
index 0000000..69935e6
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock.h
@@ -0,0 +1,61 @@
+/*
+ * Hardware spinlocks internal header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __HWSPINLOCK_HWSPINLOCK_H
+#define __HWSPINLOCK_HWSPINLOCK_H
+
+#include <linux/spinlock.h>
+#include <linux/device.h>
+
+/**
+ * struct hwspinlock_ops - platform-specific hwspinlock handlers
+ *
+ * @trylock: make a single attempt to take the lock. returns 0 on
+ * failure and true on success. may _not_ sleep.
+ * @unlock: release the lock. always succeed. may _not_ sleep.
+ * @relax: optional, platform-specific relax handler, called by hwspinlock
+ * core while spinning on a lock, between two successive
+ * invocations of @trylock. may _not_ sleep.
+ */
+struct hwspinlock_ops {
+ int (*trylock)(struct hwspinlock *lock);
+ void (*unlock)(struct hwspinlock *lock);
+ void (*relax)(struct hwspinlock *lock);
+};
+
+/**
+ * struct hwspinlock - this struct represents a single hwspinlock instance
+ *
+ * @dev: underlying device, will be used to invoke runtime PM api
+ * @ops: platform-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ *
+ * Note: currently simplicity was opted for, but later we can squeeze some
+ * memory bytes by grouping the dev, ops and owner members in a single
+ * per-platform struct, and have all hwspinlocks point at it.
+ */
+struct hwspinlock {
+ struct device *dev;
+ const struct hwspinlock_ops *ops;
+ int id;
+ spinlock_t lock;
+ struct module *owner;
+};
+
+#endif /* __HWSPINLOCK_HWSPINLOCK_H */
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
new file mode 100644
index 0000000..1782c87
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -0,0 +1,557 @@
+/*
+ * Hardware spinlock framework
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/jiffies.h>
+#include <linux/radix-tree.h>
+#include <linux/hwspinlock.h>
+#include <linux/pm_runtime.h>
+
+#include "hwspinlock.h"
+
+/* radix tree tags */
+#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */
+
+/*
+ * A radix tree is used to maintain the available hwspinlock instances.
+ * The tree associates hwspinlock pointers with their integer key id,
+ * and provides easy-to-use API which makes the hwspinlock core code simple
+ * and easy to read.
+ *
+ * Radix trees are quick on lookups, and reasonably efficient in terms of
+ * storage, especially with high density usages such as this framework
+ * requires (a continuous range of integer keys, beginning with zero, is
+ * used as the ID's of the hwspinlock instances).
+ *
+ * The radix tree API supports tagging items in the tree, which this
+ * framework uses to mark unused hwspinlock instances (see the
+ * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the
+ * tree, looking for an unused hwspinlock instance, is now reduced to a
+ * single radix tree API call.
+ */
+static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
+
+/*
+ * Synchronization of access to the tree is achieved using this spinlock,
+ * as the radix-tree API requires that users provide all synchronisation.
+ */
+static DEFINE_SPINLOCK(hwspinlock_tree_lock);
+
+/**
+ * __hwspin_trylock() - attempt to lock a specific hwspinlock
+ * @hwlock: an hwspinlock which we want to trylock
+ * @mode: controls whether local interrupts are disabled or not
+ * @flags: a pointer where the caller's interrupt state will be saved at (if
+ * requested)
+ *
+ * This function attempts to lock an hwspinlock, and will immediately
+ * fail if the hwspinlock is already taken.
+ *
+ * Upon a successful return from this function, preemption (and possibly
+ * interrupts) is disabled, so the caller must not sleep, and is advised to
+ * release the hwspinlock as soon as possible. This is required in order to
+ * minimize remote cores polling on the hardware interconnect.
+ *
+ * The user decides whether local interrupts are disabled or not, and if yes,
+ * whether he wants their previous state to be saved. It is up to the user
+ * to choose the appropriate @mode of operation, exactly the same way users
+ * should decide between spin_trylock, spin_trylock_irq and
+ * spin_trylock_irqsave.
+ *
+ * Returns 0 if we successfully locked the hwspinlock or -EBUSY if
+ * the hwspinlock was already taken.
+ * This function will never sleep.
+ */
+int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ int ret;
+
+ BUG_ON(!hwlock);
+ BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
+
+ /*
+ * This spin_lock{_irq, _irqsave} serves three purposes:
+ *
+ * 1. Disable preemption, in order to minimize the period of time
+ * in which the hwspinlock is taken. This is important in order
+ * to minimize the possible polling on the hardware interconnect
+ * by a remote user of this lock.
+ * 2. Make the hwspinlock SMP-safe (so we can take it from
+ * additional contexts on the local host).
+ * 3. Ensure that in_atomic/might_sleep checks catch potential
+ * problems with hwspinlock usage (e.g. scheduler checks like
+ * 'scheduling while atomic' etc.)
+ */
+ if (mode == HWLOCK_IRQSTATE)
+ ret = spin_trylock_irqsave(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ ret = spin_trylock_irq(&hwlock->lock);
+ else
+ ret = spin_trylock(&hwlock->lock);
+
+ /* is lock already taken by another context on the local cpu ? */
+ if (!ret)
+ return -EBUSY;
+
+ /* try to take the hwspinlock device */
+ ret = hwlock->ops->trylock(hwlock);
+
+ /* if hwlock is already taken, undo spin_trylock_* and exit */
+ if (!ret) {
+ if (mode == HWLOCK_IRQSTATE)
+ spin_unlock_irqrestore(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ spin_unlock_irq(&hwlock->lock);
+ else
+ spin_unlock(&hwlock->lock);
+
+ return -EBUSY;
+ }
+
+ /*
+ * We can be sure the other core's memory operations
+ * are observable to us only _after_ we successfully take
+ * the hwspinlock, and we must make sure that subsequent memory
+ * operations (both reads and writes) will not be reordered before
+ * we actually took the hwspinlock.
+ *
+ * Note: the implicit memory barrier of the spinlock above is too
+ * early, so we need this additional explicit memory barrier.
+ */
+ mb();
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__hwspin_trylock);
+
+/**
+ * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit
+ * @hwlock: the hwspinlock to be locked
+ * @timeout: timeout value in jiffies
+ * @mode: mode which controls whether local interrupts are disabled or not
+ * @flags: a pointer to where the caller's interrupt state will be saved at (if
+ * requested)
+ *
+ * This function locks the given @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption is disabled
+ * (and possibly local interrupts, too), so the caller must not sleep,
+ * and is advised to release the hwspinlock as soon as possible.
+ * This is required in order to minimize remote cores polling on the
+ * hardware interconnect.
+ *
+ * The user decides whether local interrupts are disabled or not, and if yes,
+ * whether he wants their previous state to be saved. It is up to the user
+ * to choose the appropriate @mode of operation, exactly the same way users
+ * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+int __hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to,
+ int mode, unsigned long *flags)
+{
+ int ret;
+ unsigned long expire;
+
+ if (to < 0) {
+ dev_err(hwlock->dev, "%s: wrong timeout value %lx\n",
+ __func__, to);
+ return -EINVAL;
+ }
+
+ expire = to + jiffies;
+
+ for (;;) {
+ /* Try to take the hwspinlock */
+ ret = __hwspin_trylock(hwlock, mode, flags);
+ if (ret != -EBUSY)
+ break;
+
+ /*
+ * The lock is already taken, let's check if the user wants
+ * us to try again
+ */
+ if (to != MAX_SCHEDULE_TIMEOUT &&
+ time_is_before_eq_jiffies(expire))
+ return -ETIMEDOUT;
+
+ /*
+ * Allow platform-specific relax handlers to prevent
+ * hogging the interconnect (no sleeping, though)
+ */
+ if (hwlock->ops->relax)
+ hwlock->ops->relax(hwlock);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__hwspin_lock_timeout);
+
+/**
+ * __hwspin_unlock() - unlock a specific hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ * @mode: controls whether local interrupts needs to be restored or not
+ * @flags: previous caller's interrupt state to restore (if requested)
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * (possibly) enable interrupts or restore their previous state.
+ * @hwlock must be already locked before calling this function: it is a bug
+ * to call unlock on a @hwlock that is already unlocked.
+ *
+ * The user decides whether local interrupts should be enabled or not, and
+ * if yes, whether he wants their previous state to be restored. It is up
+ * to the user to choose the appropriate @mode of operation, exactly the
+ * same way users decide between spin_unlock, spin_unlock_irq and
+ * spin_unlock_irqrestore.
+ *
+ * The function will never sleep.
+ */
+void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ BUG_ON(!hwlock);
+ BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
+
+ /*
+ * We must make sure that memory operations (both reads and writes),
+ * done before unlocking the hwspinlock, will not be reordered
+ * after the lock is released.
+ *
+ * That's the purpose of this explicit memory barrier.
+ *
+ * Note: the memory barrier induced by the spin_unlock below is too
+ * late; the other core is going to access memory soon after it will
+ * take the hwspinlock, and by then we want to be sure our memory
+ * operations are already observable.
+ */
+ mb();
+
+ hwlock->ops->unlock(hwlock);
+
+ /* Undo the spin_trylock{_irq, _irqsave} called while locking */
+ if (mode == HWLOCK_IRQSTATE)
+ spin_unlock_irqrestore(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ spin_unlock_irq(&hwlock->lock);
+ else
+ spin_unlock(&hwlock->lock);
+}
+EXPORT_SYMBOL_GPL(__hwspin_unlock);
+
+/**
+ * hwspin_lock_register() - register a new hw spinlock
+ * @hwlock: hwspinlock to register.
+ *
+ * This function should be called from the underlying platform-specific
+ * implementation, to register a new hwspinlock instance.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context.
+ *
+ * Returns 0 on success, or an appropriate error code on failure
+ */
+int hwspin_lock_register(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ if (!hwlock || !hwlock->ops ||
+ !hwlock->ops->trylock || !hwlock->ops->unlock) {
+ pr_err("invalid parameters\n");
+ return -EINVAL;
+ }
+
+ spin_lock_init(&hwlock->lock);
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ ret = radix_tree_insert(&hwspinlock_tree, hwlock->id, hwlock);
+ if (ret)
+ goto out;
+
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* self-sanity check which should never fail */
+ WARN_ON(tmp != hwlock);
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_register);
+
+/**
+ * hwspin_lock_unregister() - unregister an hw spinlock
+ * @id: index of the specific hwspinlock to unregister
+ *
+ * This function should be called from the underlying platform-specific
+ * implementation, to unregister an existing (and unused) hwspinlock.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context.
+ *
+ * Returns the address of hwspinlock @id on success, or NULL on failure
+ */
+struct hwspinlock *hwspin_lock_unregister(unsigned int id)
+{
+ struct hwspinlock *hwlock = NULL;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure the hwspinlock is not in use (tag is set) */
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_err("hwspinlock %d still in use (or not present)\n", id);
+ goto out;
+ }
+
+ hwlock = radix_tree_delete(&hwspinlock_tree, id);
+ if (!hwlock) {
+ pr_err("failed to delete hwspinlock %d\n", id);
+ goto out;
+ }
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
+
+/**
+ * __hwspin_lock_request() - tag an hwspinlock as used and power it up
+ *
+ * This is an internal function that prepares an hwspinlock instance
+ * before it is given to the user. The function assumes that
+ * hwspinlock_tree_lock is taken.
+ *
+ * Returns 0 or positive to indicate success, and a negative value to
+ * indicate an error (with the appropriate error code)
+ */
+static int __hwspin_lock_request(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ /* prevent underlying implementation from being removed */
+ if (!try_module_get(hwlock->owner)) {
+ dev_err(hwlock->dev, "%s: can't get owner\n", __func__);
+ return -EINVAL;
+ }
+
+ /* notify PM core that power is now needed */
+ ret = pm_runtime_get_sync(hwlock->dev);
+ if (ret < 0) {
+ dev_err(hwlock->dev, "%s: can't power on device\n", __func__);
+ return ret;
+ }
+
+ /* mark hwspinlock as used, should not fail */
+ tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* self-sanity check that should never fail */
+ WARN_ON(tmp != hwlock);
+
+ return ret;
+}
+
+/**
+ * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
+ * @hwlock: a valid hwspinlock instance
+ *
+ * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
+ */
+int hwspin_lock_get_id(struct hwspinlock *hwlock)
+{
+ if (!hwlock) {
+ pr_err("invalid hwlock\n");
+ return -EINVAL;
+ }
+
+ return hwlock->id;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
+
+/**
+ * hwspin_lock_request() - request an hwspinlock
+ *
+ * This function should be called by users of the hwspinlock device,
+ * in order to dynamically assign them an unused hwspinlock.
+ * Usually the user of this lock will then have to communicate the lock's id
+ * to the remote core before it can be used for synchronization (to get the
+ * id of a given hwlock, use hwspin_lock_get_id()).
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns the address of the assigned hwspinlock, or NULL on error
+ */
+struct hwspinlock *hwspin_lock_request(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* look for an unused lock */
+ ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
+ 0, 1, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_warn("a free hwspinlock is not available\n");
+ hwlock = NULL;
+ goto out;
+ }
+
+ /* sanity check that should never fail */
+ WARN_ON(ret > 1);
+
+ /* mark as used and power up */
+ ret = __hwspin_lock_request(hwlock);
+ if (ret < 0)
+ hwlock = NULL;
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_request);
+
+/**
+ * hwspin_lock_request_specific() - request for a specific hwspinlock
+ * @id: index of the specific hwspinlock that is requested
+ *
+ * This function should be called by users of the hwspinlock module,
+ * in order to assign them a specific hwspinlock.
+ * Usually early board code will be calling this function in order to
+ * reserve specific hwspinlock ids for predefined purposes.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns the address of the assigned hwspinlock, or NULL on error
+ */
+struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure this hwspinlock exists */
+ hwlock = radix_tree_lookup(&hwspinlock_tree, id);
+ if (!hwlock) {
+ pr_warn("hwspinlock %u does not exist\n", id);
+ goto out;
+ }
+
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(hwlock->id != id);
+
+ /* make sure this hwspinlock is unused */
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_warn("hwspinlock %u is already in use\n", id);
+ hwlock = NULL;
+ goto out;
+ }
+
+ /* mark as used and power up */
+ ret = __hwspin_lock_request(hwlock);
+ if (ret < 0)
+ hwlock = NULL;
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
+
+/**
+ * hwspin_lock_free() - free a specific hwspinlock
+ * @hwlock: the specific hwspinlock to free
+ *
+ * This function mark @hwlock as free again.
+ * Should only be called with an @hwlock that was retrieved from
+ * an earlier call to omap_hwspin_lock_request{_specific}.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns 0 on success, or an appropriate error code on failure
+ */
+int hwspin_lock_free(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ if (!hwlock) {
+ pr_err("invalid hwlock\n");
+ return -EINVAL;
+ }
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure the hwspinlock is used */
+ ret = radix_tree_tag_get(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+ if (ret == 1) {
+ dev_err(hwlock->dev, "%s: hwlock is already free\n", __func__);
+ dump_stack();
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* notify the underlying device that power is not needed */
+ ret = pm_runtime_put(hwlock->dev);
+ if (ret < 0)
+ goto out;
+
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(tmp != hwlock);
+
+ module_put(hwlock->owner);
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_free);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock interface");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h
new file mode 100644
index 0000000..47a6b1c
--- /dev/null
+++ b/include/linux/hwspinlock.h
@@ -0,0 +1,298 @@
+/*
+ * Hardware spinlock public header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_HWSPINLOCK_H
+#define __LINUX_HWSPINLOCK_H
+
+#include <linux/err.h>
+#include <linux/sched.h>
+
+/* hwspinlock mode argument */
+#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
+#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
+
+struct hwspinlock;
+
+#if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE)
+
+int hwspin_lock_register(struct hwspinlock *lock);
+struct hwspinlock *hwspin_lock_unregister(unsigned int id);
+struct hwspinlock *hwspin_lock_request(void);
+struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
+int hwspin_lock_free(struct hwspinlock *hwlock);
+int hwspin_lock_get_id(struct hwspinlock *hwlock);
+int __hwspin_lock_timeout(struct hwspinlock *, signed long, int,
+ unsigned long *);
+int __hwspin_trylock(struct hwspinlock *, int, unsigned long *);
+void __hwspin_unlock(struct hwspinlock *, int, unsigned long *);
+
+#else /* !CONFIG_HWSPINLOCK */
+
+/*
+ * We don't want these functions to fail if CONFIG_HWSPINLOCK is not
+ * enabled. We prefer to silently succeed in this case, and let the
+ * code path get compiled away. This way, if CONFIG_HWSPINLOCK is not
+ * required on a given setup, users will still work.
+ *
+ * The only exception is hwspin_lock_register/hwspin_lock_unregister, with which
+ * we _do_ want users to fail (no point in registering hwspinlock instances if
+ * the framework is not available).
+ *
+ * Note: ERR_PTR(-ENODEV) will still be considered a success for NULL-checking
+ * users. Others, which care, can still check this with IS_ERR.
+ */
+static inline struct hwspinlock *hwspin_lock_request(void)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline int hwspin_lock_free(struct hwspinlock *hwlock)
+{
+ return 0;
+}
+
+static inline
+int __hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to,
+ int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline
+int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline
+void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline int hwspin_lock_get_id(struct hwspinlock *hwlock)
+{
+ return 0;
+}
+
+static inline int hwspin_lock_register(struct hwspinlock *hwlock)
+{
+ return -ENODEV;
+}
+
+static inline struct hwspinlock *hwspin_lock_unregister(unsigned int id)
+{
+ return NULL;
+}
+
+#endif /* !CONFIG_HWSPINLOCK */
+
+/**
+ * hwspin_trylock_irqsave() - try to lock an hwspinlock, disable interrupts
+ * @hwlock: an hwspinlock which we want to trylock
+ * @flags: a pointer to where the caller's interrupt state will be saved at
+ *
+ * This function attempts to lock the underlying hwspinlock, and will
+ * immediately fail if the hwspinlock is already locked.
+ *
+ * Upon a successful return from this function, preemption and local
+ * interrupts are disabled (previous interrupts state is saved at @flags),
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline
+int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags)
+{
+ return __hwspin_trylock(hwlock, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_trylock_irq() - try to lock an hwspinlock, disable interrupts
+ * @hwlock: an hwspinlock which we want to trylock
+ *
+ * This function attempts to lock the underlying hwspinlock, and will
+ * immediately fail if the hwspinlock is already locked.
+ *
+ * Upon a successful return from this function, preemption and local
+ * interrupts are disabled, so the caller must not sleep, and is advised
+ * to release the hwspinlock as soon as possible.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline int hwspin_trylock_irq(struct hwspinlock *hwlock)
+{
+ return __hwspin_trylock(hwlock, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_trylock() - attempt to lock a specific hwspinlock
+ * @hwlock: an hwspinlock which we want to trylock
+ *
+ * This function attempts to lock an hwspinlock, and will immediately fail
+ * if the hwspinlock is already taken.
+ *
+ * Upon a successful return from this function, preemption is disabled,
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible. This is required in order to minimize remote cores
+ * polling on the hardware interconnect.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline int hwspin_trylock(struct hwspinlock *hwlock)
+{
+ return __hwspin_trylock(hwlock, 0, NULL);
+}
+
+/**
+ * hwspin_lock_timeout_irqsave() - lock hwspinlock, with timeout, disable irqs
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ * @flags: a pointer to where the caller's interrupt state will be saved at
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption and local interrupts
+ * are disabled (plus previous interrupt state is saved), so the caller must
+ * not sleep, and is advised to release the hwspinlock as soon as possible.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock,
+ signed long to, unsigned long *flags)
+{
+ return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_lock_timeout_irq() - lock hwspinlock, with timeout, disable irqs
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption and local interrupts
+ * are disabled so the caller must not sleep, and is advised to release the
+ * hwspinlock as soon as possible.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline
+int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, signed long to)
+{
+ return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_lock_timeout() - lock an hwspinlock with timeout limit
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption is disabled
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible.
+ * This is required in order to minimize remote cores polling on the
+ * hardware interconnect.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline
+int hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to)
+{
+ return __hwspin_lock_timeout(hwlock, to, 0, NULL);
+}
+
+/**
+ * hwspin_unlock_irqrestore() - unlock hwspinlock, restore irq state
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ * @flags: previous caller's interrupt state to restore
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * restore the previous state of the local interrupts. It should be used
+ * to undo, e.g., hwspin_trylock_irqsave().
+ *
+ * @hwlock must be already locked before calling this function: it is a bug
+ * to call unlock on a @hwlock that is already unlocked.
+ */
+static inline void hwspin_unlock_irqrestore(struct hwspinlock *hwlock,
+ unsigned long *flags)
+{
+ __hwspin_unlock(hwlock, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_unlock_irq() - unlock hwspinlock, enable interrupts
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * enable local interrupts. Should be used to undo hwspin_lock_irq().
+ *
+ * @hwlock must be already locked (e.g. by hwspin_trylock_irq()) before
+ * calling this function: it is a bug to call unlock on a @hwlock that is
+ * already unlocked.
+ */
+static inline void hwspin_unlock_irq(struct hwspinlock *hwlock)
+{
+ __hwspin_unlock(hwlock, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_unlock() - unlock hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ *
+ * This function will unlock a specific hwspinlock and enable preemption
+ * back.
+ *
+ * @hwlock must be already locked (e.g. by hwspin_trylock()) before calling
+ * this function: it is a bug to call unlock on a @hwlock that is already
+ * unlocked.
+ */
+static inline void hwspin_unlock(struct hwspinlock *hwlock)
+{
+ __hwspin_unlock(hwlock, 0, NULL);
+}
+
+#endif /* __LINUX_HWSPINLOCK_H */
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 1/4] drivers: hwspinlock: add framework
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann
Add a platform-independent hwspinlock framework.
Hardware spinlock devices are needed, e.g., in order to access data
that is shared between remote processors, that otherwise have no
alternative mechanism to accomplish synchronization and mutual exclusion
operations.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Hari Kanigeri <h-kanigeri2@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
Documentation/hwspinlock.txt | 299 ++++++++++++++++++
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/hwspinlock/Kconfig | 13 +
drivers/hwspinlock/Makefile | 5 +
drivers/hwspinlock/hwspinlock.h | 61 ++++
drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++++++++
include/linux/hwspinlock.h | 298 ++++++++++++++++++
8 files changed, 1236 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwspinlock.txt
create mode 100644 drivers/hwspinlock/Kconfig
create mode 100644 drivers/hwspinlock/Makefile
create mode 100644 drivers/hwspinlock/hwspinlock.h
create mode 100644 drivers/hwspinlock/hwspinlock_core.c
create mode 100644 include/linux/hwspinlock.h
diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
new file mode 100644
index 0000000..65324ce
--- /dev/null
+++ b/Documentation/hwspinlock.txt
@@ -0,0 +1,299 @@
+Hardware Spinlock Framework
+
+1. Introduction
+
+Hardware spinlock modules provide hardware assistance for synchronization
+and mutual exclusion between heterogeneous processors and those not operating
+under a single, shared operating system.
+
+For example, OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP,
+each of which is running a different Operating System (the master, A9,
+is usually running Linux and the slave processors, the M3 and the DSP,
+are running some flavor of RTOS).
+
+A generic hwspinlock framework allows platform-independent drivers to use
+the hwspinlock device in order to access data structures that are shared
+between remote processors, that otherwise have no alternative mechanism
+to accomplish synchronization and mutual exclusion operations.
+
+This is necessary, for example, for Inter-processor communications:
+on OMAP4, cpu-intensive multimedia tasks are offloaded by the host to the
+remote M3 and/or C64x+ slave processors (by an IPC subsystem called Syslink).
+
+To achieve fast message-based communications, a minimal kernel support
+is needed to deliver messages arriving from a remote processor to the
+appropriate user process.
+
+This communication is based on simple data structures that is shared between
+the remote processors, and access to it is synchronized using the hwspinlock
+module (remote processor directly places new messages in this shared data
+structure).
+
+A common hwspinlock interface makes it possible to have generic, platform-
+independent, drivers.
+
+2. User API
+
+ struct hwspinlock *hwspin_lock_request(void);
+ - dynamically assign an hwspinlock and return its address, or NULL
+ in case an unused hwspinlock isn't available. Users of this
+ API will usually want to communicate the lock's id to the remote core
+ before it can be used to achieve synchronization.
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
+ - assign a specific hwspinlock id and return its address, or NULL
+ if that hwspinlock is already in use. Usually board code will
+ be calling this function in order to reserve specific hwspinlock
+ ids for predefined purposes.
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ int hwspin_lock_free(struct hwspinlock *hwlock);
+ - free a previously-assigned hwspinlock; returns 0 on success, or an
+ appropriate error code on failure (e.g. -EINVAL if the hwspinlock
+ is already free).
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ int hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned long timeout);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption is disabled so
+ the caller must not sleep, and is advised to release the hwspinlock as
+ soon as possible, in order to minimize remote cores polling on the
+ hardware interconnect.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, unsigned long timeout);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption and the local
+ interrupts are disabled, so the caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock, unsigned long to,
+ unsigned long *flags);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption is disabled,
+ local interrupts are disabled and their previous state is saved at the
+ given flags placeholder. The caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_trylock(struct hwspinlock *hwlock);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption is disabled so
+ caller must not sleep, and is advised to release the hwspinlock as soon as
+ possible, in order to minimize remote cores polling on the hardware
+ interconnect.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ int hwspin_trylock_irq(struct hwspinlock *hwlock);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption and the local
+ interrupts are disabled so caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption is disabled,
+ the local interrupts are disabled and their previous state is saved
+ at the given flags placeholder. The caller must not sleep, and is advised
+ to release the hwspinlock as soon as possible.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ void hwspin_unlock(struct hwspinlock *hwlock);
+ - unlock a previously-locked hwspinlock. Always succeed, and can be called
+ from any context (the function never sleeps). Note: code should _never_
+ unlock an hwspinlock which is already unlocked (there is no protection
+ against this).
+
+ void hwspin_unlock_irq(struct hwspinlock *hwlock);
+ - unlock a previously-locked hwspinlock and enable local interrupts.
+ The caller should _never_ unlock an hwspinlock which is already unlocked.
+ Doing so is considered a bug (there is no protection against this).
+ Upon a successful return from this function, preemption and local
+ interrupts are enabled. This function will never sleep.
+
+ void
+ hwspin_unlock_irqrestore(struct hwspinlock *hwlock, unsigned long *flags);
+ - unlock a previously-locked hwspinlock.
+ The caller should _never_ unlock an hwspinlock which is already unlocked.
+ Doing so is considered a bug (there is no protection against this).
+ Upon a successful return from this function, preemption is reenabled,
+ and the state of the local interrupts is restored to the state saved at
+ the given flags. This function will never sleep.
+
+ int hwspin_lock_get_id(struct hwspinlock *hwlock);
+ - retrieve id number of a given hwspinlock. This is needed when an
+ hwspinlock is dynamically assigned: before it can be used to achieve
+ mutual exclusion with a remote cpu, the id number should be communicated
+ to the remote task with which we want to synchronize.
+ Returns the hwspinlock id number, or -EINVAL if hwlock is null.
+
+3. Typical usage
+
+#include <linux/hwspinlock.h>
+#include <linux/err.h>
+
+int hwspinlock_example1(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ /* dynamically assign a hwspinlock */
+ hwlock = hwspin_lock_request();
+ if (!hwlock)
+ ...
+
+ id = hwspin_lock_get_id(hwlock);
+ /* probably need to communicate id to a remote processor now */
+
+ /* take the lock, spin for 1 sec if it's already taken */
+ ret = hwspin_lock_timeout(hwlock, msecs_to_jiffies(1000));
+ if (ret)
+ ...
+
+ /*
+ * we took the lock, do our thing now, but do NOT sleep
+ */
+
+ /* release the lock */
+ hwspin_unlock(hwlock);
+
+ /* free the lock */
+ ret = hwspin_lock_free(hwlock);
+ if (ret)
+ ...
+
+ return ret;
+}
+
+int hwspinlock_example2(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ /*
+ * assign a specific hwspinlock id - this should be called early
+ * by board init code.
+ */
+ hwlock = hwspin_lock_request_specific(PREDEFINED_LOCK_ID);
+ if (!hwlock)
+ ...
+
+ /* try to take it, but don't spin on it */
+ ret = hwspin_trylock(hwlock);
+ if (!ret) {
+ pr_info("lock is already taken\n");
+ return -EBUSY;
+ }
+
+ /*
+ * we took the lock, do our thing now, but do NOT sleep
+ */
+
+ /* release the lock */
+ hwspin_unlock(hwlock);
+
+ /* free the lock */
+ ret = hwspin_lock_free(hwlock);
+ if (ret)
+ ...
+
+ return ret;
+}
+
+
+4. API for implementors
+
+ int hwspin_lock_register(struct hwspinlock *hwlock);
+ - to be called from the underlying platform-specific implementation, in
+ order to register a new hwspinlock instance. Can be called from an atomic
+ context (this function will not sleep) but not from within interrupt
+ context. Returns 0 on success, or appropriate error code on failure.
+
+ struct hwspinlock *hwspin_lock_unregister(unsigned int id);
+ - to be called from the underlying vendor-specific implementation, in order
+ to unregister an existing (and unused) hwspinlock instance.
+ Can be called from an atomic context (will not sleep) but not from
+ within interrupt context.
+ Returns the address of hwspinlock on success, or NULL on error (e.g.
+ if the hwspinlock is sill in use).
+
+5. struct hwspinlock
+
+This struct represents an hwspinlock instance. It is registered by the
+underlying hwspinlock implementation using the hwspin_lock_register() API.
+
+/**
+ * struct hwspinlock - vendor-specific hwspinlock implementation
+ *
+ * @dev: underlying device, will be used with runtime PM api
+ * @ops: vendor-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ */
+struct hwspinlock {
+ struct device *dev;
+ const struct hwspinlock_ops *ops;
+ int id;
+ spinlock_t lock;
+ struct module *owner;
+};
+
+The underlying implementation is responsible to assign the dev, ops, id and
+owner members. The lock member, OTOH, is initialized and used by the hwspinlock
+core.
+
+6. Implementation callbacks
+
+There are three possible callbacks defined in 'struct hwspinlock_ops':
+
+struct hwspinlock_ops {
+ int (*trylock)(struct hwspinlock *lock);
+ void (*unlock)(struct hwspinlock *lock);
+ void (*relax)(struct hwspinlock *lock);
+};
+
+The first two callbacks are mandatory:
+
+The ->trylock() callback should make a single attempt to take the lock, and
+return 0 on failure and 1 on success. This callback may _not_ sleep.
+
+The ->unlock() callback releases the lock. It always succeed, and it, too,
+may _not_ sleep.
+
+The ->relax() callback is optional. It is called by hwspinlock core while
+spinning on a lock, and can be used by the underlying implementation to force
+a delay between two successive invocations of ->trylock(). It may _not_ sleep.
diff --git a/drivers/Kconfig b/drivers/Kconfig
index a2b902f..c0e2eab 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -111,4 +111,6 @@ source "drivers/xen/Kconfig"
source "drivers/staging/Kconfig"
source "drivers/platform/Kconfig"
+
+source "drivers/hwspinlock/Kconfig"
endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index cafb881..bb0c472 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -115,3 +115,4 @@ obj-$(CONFIG_VLYNQ) += vlynq/
obj-$(CONFIG_STAGING) += staging/
obj-y += platform/
obj-y += ieee802154/
+obj-$(CONFIG_HWSPINLOCK) += hwspinlock/
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
new file mode 100644
index 0000000..9dd8db4
--- /dev/null
+++ b/drivers/hwspinlock/Kconfig
@@ -0,0 +1,13 @@
+#
+# Generic HWSPINLOCK framework
+#
+
+config HWSPINLOCK
+ tristate "Generic Hardware Spinlock framework"
+ help
+ Say y here to support the generic hardware spinlock framework.
+ You only need to enable this if you have hardware spinlock module
+ on your system (usually only relevant if your system has remote slave
+ coprocessors).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
new file mode 100644
index 0000000..b9d2b9f
--- /dev/null
+++ b/drivers/hwspinlock/Makefile
@@ -0,0 +1,5 @@
+#
+# Generic Hardware Spinlock framework
+#
+
+obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
diff --git a/drivers/hwspinlock/hwspinlock.h b/drivers/hwspinlock/hwspinlock.h
new file mode 100644
index 0000000..69935e6
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock.h
@@ -0,0 +1,61 @@
+/*
+ * Hardware spinlocks internal header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __HWSPINLOCK_HWSPINLOCK_H
+#define __HWSPINLOCK_HWSPINLOCK_H
+
+#include <linux/spinlock.h>
+#include <linux/device.h>
+
+/**
+ * struct hwspinlock_ops - platform-specific hwspinlock handlers
+ *
+ * @trylock: make a single attempt to take the lock. returns 0 on
+ * failure and true on success. may _not_ sleep.
+ * @unlock: release the lock. always succeed. may _not_ sleep.
+ * @relax: optional, platform-specific relax handler, called by hwspinlock
+ * core while spinning on a lock, between two successive
+ * invocations of @trylock. may _not_ sleep.
+ */
+struct hwspinlock_ops {
+ int (*trylock)(struct hwspinlock *lock);
+ void (*unlock)(struct hwspinlock *lock);
+ void (*relax)(struct hwspinlock *lock);
+};
+
+/**
+ * struct hwspinlock - this struct represents a single hwspinlock instance
+ *
+ * @dev: underlying device, will be used to invoke runtime PM api
+ * @ops: platform-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ *
+ * Note: currently simplicity was opted for, but later we can squeeze some
+ * memory bytes by grouping the dev, ops and owner members in a single
+ * per-platform struct, and have all hwspinlocks point at it.
+ */
+struct hwspinlock {
+ struct device *dev;
+ const struct hwspinlock_ops *ops;
+ int id;
+ spinlock_t lock;
+ struct module *owner;
+};
+
+#endif /* __HWSPINLOCK_HWSPINLOCK_H */
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
new file mode 100644
index 0000000..1782c87
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -0,0 +1,557 @@
+/*
+ * Hardware spinlock framework
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/jiffies.h>
+#include <linux/radix-tree.h>
+#include <linux/hwspinlock.h>
+#include <linux/pm_runtime.h>
+
+#include "hwspinlock.h"
+
+/* radix tree tags */
+#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */
+
+/*
+ * A radix tree is used to maintain the available hwspinlock instances.
+ * The tree associates hwspinlock pointers with their integer key id,
+ * and provides easy-to-use API which makes the hwspinlock core code simple
+ * and easy to read.
+ *
+ * Radix trees are quick on lookups, and reasonably efficient in terms of
+ * storage, especially with high density usages such as this framework
+ * requires (a continuous range of integer keys, beginning with zero, is
+ * used as the ID's of the hwspinlock instances).
+ *
+ * The radix tree API supports tagging items in the tree, which this
+ * framework uses to mark unused hwspinlock instances (see the
+ * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the
+ * tree, looking for an unused hwspinlock instance, is now reduced to a
+ * single radix tree API call.
+ */
+static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
+
+/*
+ * Synchronization of access to the tree is achieved using this spinlock,
+ * as the radix-tree API requires that users provide all synchronisation.
+ */
+static DEFINE_SPINLOCK(hwspinlock_tree_lock);
+
+/**
+ * __hwspin_trylock() - attempt to lock a specific hwspinlock
+ * @hwlock: an hwspinlock which we want to trylock
+ * @mode: controls whether local interrupts are disabled or not
+ * @flags: a pointer where the caller's interrupt state will be saved at (if
+ * requested)
+ *
+ * This function attempts to lock an hwspinlock, and will immediately
+ * fail if the hwspinlock is already taken.
+ *
+ * Upon a successful return from this function, preemption (and possibly
+ * interrupts) is disabled, so the caller must not sleep, and is advised to
+ * release the hwspinlock as soon as possible. This is required in order to
+ * minimize remote cores polling on the hardware interconnect.
+ *
+ * The user decides whether local interrupts are disabled or not, and if yes,
+ * whether he wants their previous state to be saved. It is up to the user
+ * to choose the appropriate @mode of operation, exactly the same way users
+ * should decide between spin_trylock, spin_trylock_irq and
+ * spin_trylock_irqsave.
+ *
+ * Returns 0 if we successfully locked the hwspinlock or -EBUSY if
+ * the hwspinlock was already taken.
+ * This function will never sleep.
+ */
+int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ int ret;
+
+ BUG_ON(!hwlock);
+ BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
+
+ /*
+ * This spin_lock{_irq, _irqsave} serves three purposes:
+ *
+ * 1. Disable preemption, in order to minimize the period of time
+ * in which the hwspinlock is taken. This is important in order
+ * to minimize the possible polling on the hardware interconnect
+ * by a remote user of this lock.
+ * 2. Make the hwspinlock SMP-safe (so we can take it from
+ * additional contexts on the local host).
+ * 3. Ensure that in_atomic/might_sleep checks catch potential
+ * problems with hwspinlock usage (e.g. scheduler checks like
+ * 'scheduling while atomic' etc.)
+ */
+ if (mode == HWLOCK_IRQSTATE)
+ ret = spin_trylock_irqsave(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ ret = spin_trylock_irq(&hwlock->lock);
+ else
+ ret = spin_trylock(&hwlock->lock);
+
+ /* is lock already taken by another context on the local cpu ? */
+ if (!ret)
+ return -EBUSY;
+
+ /* try to take the hwspinlock device */
+ ret = hwlock->ops->trylock(hwlock);
+
+ /* if hwlock is already taken, undo spin_trylock_* and exit */
+ if (!ret) {
+ if (mode == HWLOCK_IRQSTATE)
+ spin_unlock_irqrestore(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ spin_unlock_irq(&hwlock->lock);
+ else
+ spin_unlock(&hwlock->lock);
+
+ return -EBUSY;
+ }
+
+ /*
+ * We can be sure the other core's memory operations
+ * are observable to us only _after_ we successfully take
+ * the hwspinlock, and we must make sure that subsequent memory
+ * operations (both reads and writes) will not be reordered before
+ * we actually took the hwspinlock.
+ *
+ * Note: the implicit memory barrier of the spinlock above is too
+ * early, so we need this additional explicit memory barrier.
+ */
+ mb();
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__hwspin_trylock);
+
+/**
+ * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit
+ * @hwlock: the hwspinlock to be locked
+ * @timeout: timeout value in jiffies
+ * @mode: mode which controls whether local interrupts are disabled or not
+ * @flags: a pointer to where the caller's interrupt state will be saved at (if
+ * requested)
+ *
+ * This function locks the given @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption is disabled
+ * (and possibly local interrupts, too), so the caller must not sleep,
+ * and is advised to release the hwspinlock as soon as possible.
+ * This is required in order to minimize remote cores polling on the
+ * hardware interconnect.
+ *
+ * The user decides whether local interrupts are disabled or not, and if yes,
+ * whether he wants their previous state to be saved. It is up to the user
+ * to choose the appropriate @mode of operation, exactly the same way users
+ * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+int __hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to,
+ int mode, unsigned long *flags)
+{
+ int ret;
+ unsigned long expire;
+
+ if (to < 0) {
+ dev_err(hwlock->dev, "%s: wrong timeout value %lx\n",
+ __func__, to);
+ return -EINVAL;
+ }
+
+ expire = to + jiffies;
+
+ for (;;) {
+ /* Try to take the hwspinlock */
+ ret = __hwspin_trylock(hwlock, mode, flags);
+ if (ret != -EBUSY)
+ break;
+
+ /*
+ * The lock is already taken, let's check if the user wants
+ * us to try again
+ */
+ if (to != MAX_SCHEDULE_TIMEOUT &&
+ time_is_before_eq_jiffies(expire))
+ return -ETIMEDOUT;
+
+ /*
+ * Allow platform-specific relax handlers to prevent
+ * hogging the interconnect (no sleeping, though)
+ */
+ if (hwlock->ops->relax)
+ hwlock->ops->relax(hwlock);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__hwspin_lock_timeout);
+
+/**
+ * __hwspin_unlock() - unlock a specific hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ * @mode: controls whether local interrupts needs to be restored or not
+ * @flags: previous caller's interrupt state to restore (if requested)
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * (possibly) enable interrupts or restore their previous state.
+ * @hwlock must be already locked before calling this function: it is a bug
+ * to call unlock on a @hwlock that is already unlocked.
+ *
+ * The user decides whether local interrupts should be enabled or not, and
+ * if yes, whether he wants their previous state to be restored. It is up
+ * to the user to choose the appropriate @mode of operation, exactly the
+ * same way users decide between spin_unlock, spin_unlock_irq and
+ * spin_unlock_irqrestore.
+ *
+ * The function will never sleep.
+ */
+void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ BUG_ON(!hwlock);
+ BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
+
+ /*
+ * We must make sure that memory operations (both reads and writes),
+ * done before unlocking the hwspinlock, will not be reordered
+ * after the lock is released.
+ *
+ * That's the purpose of this explicit memory barrier.
+ *
+ * Note: the memory barrier induced by the spin_unlock below is too
+ * late; the other core is going to access memory soon after it will
+ * take the hwspinlock, and by then we want to be sure our memory
+ * operations are already observable.
+ */
+ mb();
+
+ hwlock->ops->unlock(hwlock);
+
+ /* Undo the spin_trylock{_irq, _irqsave} called while locking */
+ if (mode == HWLOCK_IRQSTATE)
+ spin_unlock_irqrestore(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ spin_unlock_irq(&hwlock->lock);
+ else
+ spin_unlock(&hwlock->lock);
+}
+EXPORT_SYMBOL_GPL(__hwspin_unlock);
+
+/**
+ * hwspin_lock_register() - register a new hw spinlock
+ * @hwlock: hwspinlock to register.
+ *
+ * This function should be called from the underlying platform-specific
+ * implementation, to register a new hwspinlock instance.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context.
+ *
+ * Returns 0 on success, or an appropriate error code on failure
+ */
+int hwspin_lock_register(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ if (!hwlock || !hwlock->ops ||
+ !hwlock->ops->trylock || !hwlock->ops->unlock) {
+ pr_err("invalid parameters\n");
+ return -EINVAL;
+ }
+
+ spin_lock_init(&hwlock->lock);
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ ret = radix_tree_insert(&hwspinlock_tree, hwlock->id, hwlock);
+ if (ret)
+ goto out;
+
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* self-sanity check which should never fail */
+ WARN_ON(tmp != hwlock);
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_register);
+
+/**
+ * hwspin_lock_unregister() - unregister an hw spinlock
+ * @id: index of the specific hwspinlock to unregister
+ *
+ * This function should be called from the underlying platform-specific
+ * implementation, to unregister an existing (and unused) hwspinlock.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context.
+ *
+ * Returns the address of hwspinlock @id on success, or NULL on failure
+ */
+struct hwspinlock *hwspin_lock_unregister(unsigned int id)
+{
+ struct hwspinlock *hwlock = NULL;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure the hwspinlock is not in use (tag is set) */
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_err("hwspinlock %d still in use (or not present)\n", id);
+ goto out;
+ }
+
+ hwlock = radix_tree_delete(&hwspinlock_tree, id);
+ if (!hwlock) {
+ pr_err("failed to delete hwspinlock %d\n", id);
+ goto out;
+ }
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
+
+/**
+ * __hwspin_lock_request() - tag an hwspinlock as used and power it up
+ *
+ * This is an internal function that prepares an hwspinlock instance
+ * before it is given to the user. The function assumes that
+ * hwspinlock_tree_lock is taken.
+ *
+ * Returns 0 or positive to indicate success, and a negative value to
+ * indicate an error (with the appropriate error code)
+ */
+static int __hwspin_lock_request(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ /* prevent underlying implementation from being removed */
+ if (!try_module_get(hwlock->owner)) {
+ dev_err(hwlock->dev, "%s: can't get owner\n", __func__);
+ return -EINVAL;
+ }
+
+ /* notify PM core that power is now needed */
+ ret = pm_runtime_get_sync(hwlock->dev);
+ if (ret < 0) {
+ dev_err(hwlock->dev, "%s: can't power on device\n", __func__);
+ return ret;
+ }
+
+ /* mark hwspinlock as used, should not fail */
+ tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* self-sanity check that should never fail */
+ WARN_ON(tmp != hwlock);
+
+ return ret;
+}
+
+/**
+ * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
+ * @hwlock: a valid hwspinlock instance
+ *
+ * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
+ */
+int hwspin_lock_get_id(struct hwspinlock *hwlock)
+{
+ if (!hwlock) {
+ pr_err("invalid hwlock\n");
+ return -EINVAL;
+ }
+
+ return hwlock->id;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
+
+/**
+ * hwspin_lock_request() - request an hwspinlock
+ *
+ * This function should be called by users of the hwspinlock device,
+ * in order to dynamically assign them an unused hwspinlock.
+ * Usually the user of this lock will then have to communicate the lock's id
+ * to the remote core before it can be used for synchronization (to get the
+ * id of a given hwlock, use hwspin_lock_get_id()).
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns the address of the assigned hwspinlock, or NULL on error
+ */
+struct hwspinlock *hwspin_lock_request(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* look for an unused lock */
+ ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
+ 0, 1, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_warn("a free hwspinlock is not available\n");
+ hwlock = NULL;
+ goto out;
+ }
+
+ /* sanity check that should never fail */
+ WARN_ON(ret > 1);
+
+ /* mark as used and power up */
+ ret = __hwspin_lock_request(hwlock);
+ if (ret < 0)
+ hwlock = NULL;
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_request);
+
+/**
+ * hwspin_lock_request_specific() - request for a specific hwspinlock
+ * @id: index of the specific hwspinlock that is requested
+ *
+ * This function should be called by users of the hwspinlock module,
+ * in order to assign them a specific hwspinlock.
+ * Usually early board code will be calling this function in order to
+ * reserve specific hwspinlock ids for predefined purposes.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns the address of the assigned hwspinlock, or NULL on error
+ */
+struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure this hwspinlock exists */
+ hwlock = radix_tree_lookup(&hwspinlock_tree, id);
+ if (!hwlock) {
+ pr_warn("hwspinlock %u does not exist\n", id);
+ goto out;
+ }
+
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(hwlock->id != id);
+
+ /* make sure this hwspinlock is unused */
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_warn("hwspinlock %u is already in use\n", id);
+ hwlock = NULL;
+ goto out;
+ }
+
+ /* mark as used and power up */
+ ret = __hwspin_lock_request(hwlock);
+ if (ret < 0)
+ hwlock = NULL;
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
+
+/**
+ * hwspin_lock_free() - free a specific hwspinlock
+ * @hwlock: the specific hwspinlock to free
+ *
+ * This function mark @hwlock as free again.
+ * Should only be called with an @hwlock that was retrieved from
+ * an earlier call to omap_hwspin_lock_request{_specific}.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns 0 on success, or an appropriate error code on failure
+ */
+int hwspin_lock_free(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ if (!hwlock) {
+ pr_err("invalid hwlock\n");
+ return -EINVAL;
+ }
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure the hwspinlock is used */
+ ret = radix_tree_tag_get(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+ if (ret == 1) {
+ dev_err(hwlock->dev, "%s: hwlock is already free\n", __func__);
+ dump_stack();
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* notify the underlying device that power is not needed */
+ ret = pm_runtime_put(hwlock->dev);
+ if (ret < 0)
+ goto out;
+
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(tmp != hwlock);
+
+ module_put(hwlock->owner);
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_free);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock interface");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h
new file mode 100644
index 0000000..47a6b1c
--- /dev/null
+++ b/include/linux/hwspinlock.h
@@ -0,0 +1,298 @@
+/*
+ * Hardware spinlock public header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_HWSPINLOCK_H
+#define __LINUX_HWSPINLOCK_H
+
+#include <linux/err.h>
+#include <linux/sched.h>
+
+/* hwspinlock mode argument */
+#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
+#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
+
+struct hwspinlock;
+
+#if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE)
+
+int hwspin_lock_register(struct hwspinlock *lock);
+struct hwspinlock *hwspin_lock_unregister(unsigned int id);
+struct hwspinlock *hwspin_lock_request(void);
+struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
+int hwspin_lock_free(struct hwspinlock *hwlock);
+int hwspin_lock_get_id(struct hwspinlock *hwlock);
+int __hwspin_lock_timeout(struct hwspinlock *, signed long, int,
+ unsigned long *);
+int __hwspin_trylock(struct hwspinlock *, int, unsigned long *);
+void __hwspin_unlock(struct hwspinlock *, int, unsigned long *);
+
+#else /* !CONFIG_HWSPINLOCK */
+
+/*
+ * We don't want these functions to fail if CONFIG_HWSPINLOCK is not
+ * enabled. We prefer to silently succeed in this case, and let the
+ * code path get compiled away. This way, if CONFIG_HWSPINLOCK is not
+ * required on a given setup, users will still work.
+ *
+ * The only exception is hwspin_lock_register/hwspin_lock_unregister, with which
+ * we _do_ want users to fail (no point in registering hwspinlock instances if
+ * the framework is not available).
+ *
+ * Note: ERR_PTR(-ENODEV) will still be considered a success for NULL-checking
+ * users. Others, which care, can still check this with IS_ERR.
+ */
+static inline struct hwspinlock *hwspin_lock_request(void)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline int hwspin_lock_free(struct hwspinlock *hwlock)
+{
+ return 0;
+}
+
+static inline
+int __hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to,
+ int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline
+int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline
+void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline int hwspin_lock_get_id(struct hwspinlock *hwlock)
+{
+ return 0;
+}
+
+static inline int hwspin_lock_register(struct hwspinlock *hwlock)
+{
+ return -ENODEV;
+}
+
+static inline struct hwspinlock *hwspin_lock_unregister(unsigned int id)
+{
+ return NULL;
+}
+
+#endif /* !CONFIG_HWSPINLOCK */
+
+/**
+ * hwspin_trylock_irqsave() - try to lock an hwspinlock, disable interrupts
+ * @hwlock: an hwspinlock which we want to trylock
+ * @flags: a pointer to where the caller's interrupt state will be saved at
+ *
+ * This function attempts to lock the underlying hwspinlock, and will
+ * immediately fail if the hwspinlock is already locked.
+ *
+ * Upon a successful return from this function, preemption and local
+ * interrupts are disabled (previous interrupts state is saved at @flags),
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline
+int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags)
+{
+ return __hwspin_trylock(hwlock, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_trylock_irq() - try to lock an hwspinlock, disable interrupts
+ * @hwlock: an hwspinlock which we want to trylock
+ *
+ * This function attempts to lock the underlying hwspinlock, and will
+ * immediately fail if the hwspinlock is already locked.
+ *
+ * Upon a successful return from this function, preemption and local
+ * interrupts are disabled, so the caller must not sleep, and is advised
+ * to release the hwspinlock as soon as possible.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline int hwspin_trylock_irq(struct hwspinlock *hwlock)
+{
+ return __hwspin_trylock(hwlock, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_trylock() - attempt to lock a specific hwspinlock
+ * @hwlock: an hwspinlock which we want to trylock
+ *
+ * This function attempts to lock an hwspinlock, and will immediately fail
+ * if the hwspinlock is already taken.
+ *
+ * Upon a successful return from this function, preemption is disabled,
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible. This is required in order to minimize remote cores
+ * polling on the hardware interconnect.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline int hwspin_trylock(struct hwspinlock *hwlock)
+{
+ return __hwspin_trylock(hwlock, 0, NULL);
+}
+
+/**
+ * hwspin_lock_timeout_irqsave() - lock hwspinlock, with timeout, disable irqs
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ * @flags: a pointer to where the caller's interrupt state will be saved at
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption and local interrupts
+ * are disabled (plus previous interrupt state is saved), so the caller must
+ * not sleep, and is advised to release the hwspinlock as soon as possible.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock,
+ signed long to, unsigned long *flags)
+{
+ return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_lock_timeout_irq() - lock hwspinlock, with timeout, disable irqs
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption and local interrupts
+ * are disabled so the caller must not sleep, and is advised to release the
+ * hwspinlock as soon as possible.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline
+int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, signed long to)
+{
+ return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_lock_timeout() - lock an hwspinlock with timeout limit
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption is disabled
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible.
+ * This is required in order to minimize remote cores polling on the
+ * hardware interconnect.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline
+int hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to)
+{
+ return __hwspin_lock_timeout(hwlock, to, 0, NULL);
+}
+
+/**
+ * hwspin_unlock_irqrestore() - unlock hwspinlock, restore irq state
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ * @flags: previous caller's interrupt state to restore
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * restore the previous state of the local interrupts. It should be used
+ * to undo, e.g., hwspin_trylock_irqsave().
+ *
+ * @hwlock must be already locked before calling this function: it is a bug
+ * to call unlock on a @hwlock that is already unlocked.
+ */
+static inline void hwspin_unlock_irqrestore(struct hwspinlock *hwlock,
+ unsigned long *flags)
+{
+ __hwspin_unlock(hwlock, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_unlock_irq() - unlock hwspinlock, enable interrupts
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * enable local interrupts. Should be used to undo hwspin_lock_irq().
+ *
+ * @hwlock must be already locked (e.g. by hwspin_trylock_irq()) before
+ * calling this function: it is a bug to call unlock on a @hwlock that is
+ * already unlocked.
+ */
+static inline void hwspin_unlock_irq(struct hwspinlock *hwlock)
+{
+ __hwspin_unlock(hwlock, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_unlock() - unlock hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ *
+ * This function will unlock a specific hwspinlock and enable preemption
+ * back.
+ *
+ * @hwlock must be already locked (e.g. by hwspin_trylock()) before calling
+ * this function: it is a bug to call unlock on a @hwlock that is already
+ * unlocked.
+ */
+static inline void hwspin_unlock(struct hwspinlock *hwlock)
+{
+ __hwspin_unlock(hwlock, 0, NULL);
+}
+
+#endif /* __LINUX_HWSPINLOCK_H */
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 1/4] drivers: hwspinlock: add framework
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-arm-kernel
Add a platform-independent hwspinlock framework.
Hardware spinlock devices are needed, e.g., in order to access data
that is shared between remote processors, that otherwise have no
alternative mechanism to accomplish synchronization and mutual exclusion
operations.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Hari Kanigeri <h-kanigeri2@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
Documentation/hwspinlock.txt | 299 ++++++++++++++++++
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/hwspinlock/Kconfig | 13 +
drivers/hwspinlock/Makefile | 5 +
drivers/hwspinlock/hwspinlock.h | 61 ++++
drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++++++++
include/linux/hwspinlock.h | 298 ++++++++++++++++++
8 files changed, 1236 insertions(+), 0 deletions(-)
create mode 100644 Documentation/hwspinlock.txt
create mode 100644 drivers/hwspinlock/Kconfig
create mode 100644 drivers/hwspinlock/Makefile
create mode 100644 drivers/hwspinlock/hwspinlock.h
create mode 100644 drivers/hwspinlock/hwspinlock_core.c
create mode 100644 include/linux/hwspinlock.h
diff --git a/Documentation/hwspinlock.txt b/Documentation/hwspinlock.txt
new file mode 100644
index 0000000..65324ce
--- /dev/null
+++ b/Documentation/hwspinlock.txt
@@ -0,0 +1,299 @@
+Hardware Spinlock Framework
+
+1. Introduction
+
+Hardware spinlock modules provide hardware assistance for synchronization
+and mutual exclusion between heterogeneous processors and those not operating
+under a single, shared operating system.
+
+For example, OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP,
+each of which is running a different Operating System (the master, A9,
+is usually running Linux and the slave processors, the M3 and the DSP,
+are running some flavor of RTOS).
+
+A generic hwspinlock framework allows platform-independent drivers to use
+the hwspinlock device in order to access data structures that are shared
+between remote processors, that otherwise have no alternative mechanism
+to accomplish synchronization and mutual exclusion operations.
+
+This is necessary, for example, for Inter-processor communications:
+on OMAP4, cpu-intensive multimedia tasks are offloaded by the host to the
+remote M3 and/or C64x+ slave processors (by an IPC subsystem called Syslink).
+
+To achieve fast message-based communications, a minimal kernel support
+is needed to deliver messages arriving from a remote processor to the
+appropriate user process.
+
+This communication is based on simple data structures that is shared between
+the remote processors, and access to it is synchronized using the hwspinlock
+module (remote processor directly places new messages in this shared data
+structure).
+
+A common hwspinlock interface makes it possible to have generic, platform-
+independent, drivers.
+
+2. User API
+
+ struct hwspinlock *hwspin_lock_request(void);
+ - dynamically assign an hwspinlock and return its address, or NULL
+ in case an unused hwspinlock isn't available. Users of this
+ API will usually want to communicate the lock's id to the remote core
+ before it can be used to achieve synchronization.
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
+ - assign a specific hwspinlock id and return its address, or NULL
+ if that hwspinlock is already in use. Usually board code will
+ be calling this function in order to reserve specific hwspinlock
+ ids for predefined purposes.
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ int hwspin_lock_free(struct hwspinlock *hwlock);
+ - free a previously-assigned hwspinlock; returns 0 on success, or an
+ appropriate error code on failure (e.g. -EINVAL if the hwspinlock
+ is already free).
+ Can be called from an atomic context (this function will not sleep) but
+ not from within interrupt context.
+
+ int hwspin_lock_timeout(struct hwspinlock *hwlock, unsigned long timeout);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption is disabled so
+ the caller must not sleep, and is advised to release the hwspinlock as
+ soon as possible, in order to minimize remote cores polling on the
+ hardware interconnect.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, unsigned long timeout);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption and the local
+ interrupts are disabled, so the caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock, unsigned long to,
+ unsigned long *flags);
+ - lock a previously-assigned hwspinlock with a timeout limit (specified in
+ jiffies). If the hwspinlock is already taken, the function will busy loop
+ waiting for it to be released, but give up when the timeout meets jiffies.
+ If timeout is 0, the function will never give up (therefore if a faulty
+ remote core never releases the hwspinlock, it will deadlock).
+ Upon a successful return from this function, preemption is disabled,
+ local interrupts are disabled and their previous state is saved at the
+ given flags placeholder. The caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 when successful and an appropriate error code otherwise (most
+ notably -ETIMEDOUT if the hwspinlock is still busy after timeout meets
+ jiffies). The function will never sleep.
+
+ int hwspin_trylock(struct hwspinlock *hwlock);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption is disabled so
+ caller must not sleep, and is advised to release the hwspinlock as soon as
+ possible, in order to minimize remote cores polling on the hardware
+ interconnect.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ int hwspin_trylock_irq(struct hwspinlock *hwlock);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption and the local
+ interrupts are disabled so caller must not sleep, and is advised to
+ release the hwspinlock as soon as possible.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags);
+ - attempt to lock a previously-assigned hwspinlock, but immediately fail if
+ it is already taken.
+ Upon a successful return from this function, preemption is disabled,
+ the local interrupts are disabled and their previous state is saved
+ at the given flags placeholder. The caller must not sleep, and is advised
+ to release the hwspinlock as soon as possible.
+ Returns 0 on success and an appropriate error code otherwise (most
+ notably -EBUSY if the hwspinlock was already taken).
+ The function will never sleep.
+
+ void hwspin_unlock(struct hwspinlock *hwlock);
+ - unlock a previously-locked hwspinlock. Always succeed, and can be called
+ from any context (the function never sleeps). Note: code should _never_
+ unlock an hwspinlock which is already unlocked (there is no protection
+ against this).
+
+ void hwspin_unlock_irq(struct hwspinlock *hwlock);
+ - unlock a previously-locked hwspinlock and enable local interrupts.
+ The caller should _never_ unlock an hwspinlock which is already unlocked.
+ Doing so is considered a bug (there is no protection against this).
+ Upon a successful return from this function, preemption and local
+ interrupts are enabled. This function will never sleep.
+
+ void
+ hwspin_unlock_irqrestore(struct hwspinlock *hwlock, unsigned long *flags);
+ - unlock a previously-locked hwspinlock.
+ The caller should _never_ unlock an hwspinlock which is already unlocked.
+ Doing so is considered a bug (there is no protection against this).
+ Upon a successful return from this function, preemption is reenabled,
+ and the state of the local interrupts is restored to the state saved at
+ the given flags. This function will never sleep.
+
+ int hwspin_lock_get_id(struct hwspinlock *hwlock);
+ - retrieve id number of a given hwspinlock. This is needed when an
+ hwspinlock is dynamically assigned: before it can be used to achieve
+ mutual exclusion with a remote cpu, the id number should be communicated
+ to the remote task with which we want to synchronize.
+ Returns the hwspinlock id number, or -EINVAL if hwlock is null.
+
+3. Typical usage
+
+#include <linux/hwspinlock.h>
+#include <linux/err.h>
+
+int hwspinlock_example1(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ /* dynamically assign a hwspinlock */
+ hwlock = hwspin_lock_request();
+ if (!hwlock)
+ ...
+
+ id = hwspin_lock_get_id(hwlock);
+ /* probably need to communicate id to a remote processor now */
+
+ /* take the lock, spin for 1 sec if it's already taken */
+ ret = hwspin_lock_timeout(hwlock, msecs_to_jiffies(1000));
+ if (ret)
+ ...
+
+ /*
+ * we took the lock, do our thing now, but do NOT sleep
+ */
+
+ /* release the lock */
+ hwspin_unlock(hwlock);
+
+ /* free the lock */
+ ret = hwspin_lock_free(hwlock);
+ if (ret)
+ ...
+
+ return ret;
+}
+
+int hwspinlock_example2(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ /*
+ * assign a specific hwspinlock id - this should be called early
+ * by board init code.
+ */
+ hwlock = hwspin_lock_request_specific(PREDEFINED_LOCK_ID);
+ if (!hwlock)
+ ...
+
+ /* try to take it, but don't spin on it */
+ ret = hwspin_trylock(hwlock);
+ if (!ret) {
+ pr_info("lock is already taken\n");
+ return -EBUSY;
+ }
+
+ /*
+ * we took the lock, do our thing now, but do NOT sleep
+ */
+
+ /* release the lock */
+ hwspin_unlock(hwlock);
+
+ /* free the lock */
+ ret = hwspin_lock_free(hwlock);
+ if (ret)
+ ...
+
+ return ret;
+}
+
+
+4. API for implementors
+
+ int hwspin_lock_register(struct hwspinlock *hwlock);
+ - to be called from the underlying platform-specific implementation, in
+ order to register a new hwspinlock instance. Can be called from an atomic
+ context (this function will not sleep) but not from within interrupt
+ context. Returns 0 on success, or appropriate error code on failure.
+
+ struct hwspinlock *hwspin_lock_unregister(unsigned int id);
+ - to be called from the underlying vendor-specific implementation, in order
+ to unregister an existing (and unused) hwspinlock instance.
+ Can be called from an atomic context (will not sleep) but not from
+ within interrupt context.
+ Returns the address of hwspinlock on success, or NULL on error (e.g.
+ if the hwspinlock is sill in use).
+
+5. struct hwspinlock
+
+This struct represents an hwspinlock instance. It is registered by the
+underlying hwspinlock implementation using the hwspin_lock_register() API.
+
+/**
+ * struct hwspinlock - vendor-specific hwspinlock implementation
+ *
+ * @dev: underlying device, will be used with runtime PM api
+ * @ops: vendor-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ */
+struct hwspinlock {
+ struct device *dev;
+ const struct hwspinlock_ops *ops;
+ int id;
+ spinlock_t lock;
+ struct module *owner;
+};
+
+The underlying implementation is responsible to assign the dev, ops, id and
+owner members. The lock member, OTOH, is initialized and used by the hwspinlock
+core.
+
+6. Implementation callbacks
+
+There are three possible callbacks defined in 'struct hwspinlock_ops':
+
+struct hwspinlock_ops {
+ int (*trylock)(struct hwspinlock *lock);
+ void (*unlock)(struct hwspinlock *lock);
+ void (*relax)(struct hwspinlock *lock);
+};
+
+The first two callbacks are mandatory:
+
+The ->trylock() callback should make a single attempt to take the lock, and
+return 0 on failure and 1 on success. This callback may _not_ sleep.
+
+The ->unlock() callback releases the lock. It always succeed, and it, too,
+may _not_ sleep.
+
+The ->relax() callback is optional. It is called by hwspinlock core while
+spinning on a lock, and can be used by the underlying implementation to force
+a delay between two successive invocations of ->trylock(). It may _not_ sleep.
diff --git a/drivers/Kconfig b/drivers/Kconfig
index a2b902f..c0e2eab 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -111,4 +111,6 @@ source "drivers/xen/Kconfig"
source "drivers/staging/Kconfig"
source "drivers/platform/Kconfig"
+
+source "drivers/hwspinlock/Kconfig"
endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index cafb881..bb0c472 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -115,3 +115,4 @@ obj-$(CONFIG_VLYNQ) += vlynq/
obj-$(CONFIG_STAGING) += staging/
obj-y += platform/
obj-y += ieee802154/
+obj-$(CONFIG_HWSPINLOCK) += hwspinlock/
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
new file mode 100644
index 0000000..9dd8db4
--- /dev/null
+++ b/drivers/hwspinlock/Kconfig
@@ -0,0 +1,13 @@
+#
+# Generic HWSPINLOCK framework
+#
+
+config HWSPINLOCK
+ tristate "Generic Hardware Spinlock framework"
+ help
+ Say y here to support the generic hardware spinlock framework.
+ You only need to enable this if you have hardware spinlock module
+ on your system (usually only relevant if your system has remote slave
+ coprocessors).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
new file mode 100644
index 0000000..b9d2b9f
--- /dev/null
+++ b/drivers/hwspinlock/Makefile
@@ -0,0 +1,5 @@
+#
+# Generic Hardware Spinlock framework
+#
+
+obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
diff --git a/drivers/hwspinlock/hwspinlock.h b/drivers/hwspinlock/hwspinlock.h
new file mode 100644
index 0000000..69935e6
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock.h
@@ -0,0 +1,61 @@
+/*
+ * Hardware spinlocks internal header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __HWSPINLOCK_HWSPINLOCK_H
+#define __HWSPINLOCK_HWSPINLOCK_H
+
+#include <linux/spinlock.h>
+#include <linux/device.h>
+
+/**
+ * struct hwspinlock_ops - platform-specific hwspinlock handlers
+ *
+ * @trylock: make a single attempt to take the lock. returns 0 on
+ * failure and true on success. may _not_ sleep.
+ * @unlock: release the lock. always succeed. may _not_ sleep.
+ * @relax: optional, platform-specific relax handler, called by hwspinlock
+ * core while spinning on a lock, between two successive
+ * invocations of @trylock. may _not_ sleep.
+ */
+struct hwspinlock_ops {
+ int (*trylock)(struct hwspinlock *lock);
+ void (*unlock)(struct hwspinlock *lock);
+ void (*relax)(struct hwspinlock *lock);
+};
+
+/**
+ * struct hwspinlock - this struct represents a single hwspinlock instance
+ *
+ * @dev: underlying device, will be used to invoke runtime PM api
+ * @ops: platform-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ *
+ * Note: currently simplicity was opted for, but later we can squeeze some
+ * memory bytes by grouping the dev, ops and owner members in a single
+ * per-platform struct, and have all hwspinlocks point at it.
+ */
+struct hwspinlock {
+ struct device *dev;
+ const struct hwspinlock_ops *ops;
+ int id;
+ spinlock_t lock;
+ struct module *owner;
+};
+
+#endif /* __HWSPINLOCK_HWSPINLOCK_H */
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
new file mode 100644
index 0000000..1782c87
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -0,0 +1,557 @@
+/*
+ * Hardware spinlock framework
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/jiffies.h>
+#include <linux/radix-tree.h>
+#include <linux/hwspinlock.h>
+#include <linux/pm_runtime.h>
+
+#include "hwspinlock.h"
+
+/* radix tree tags */
+#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */
+
+/*
+ * A radix tree is used to maintain the available hwspinlock instances.
+ * The tree associates hwspinlock pointers with their integer key id,
+ * and provides easy-to-use API which makes the hwspinlock core code simple
+ * and easy to read.
+ *
+ * Radix trees are quick on lookups, and reasonably efficient in terms of
+ * storage, especially with high density usages such as this framework
+ * requires (a continuous range of integer keys, beginning with zero, is
+ * used as the ID's of the hwspinlock instances).
+ *
+ * The radix tree API supports tagging items in the tree, which this
+ * framework uses to mark unused hwspinlock instances (see the
+ * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the
+ * tree, looking for an unused hwspinlock instance, is now reduced to a
+ * single radix tree API call.
+ */
+static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
+
+/*
+ * Synchronization of access to the tree is achieved using this spinlock,
+ * as the radix-tree API requires that users provide all synchronisation.
+ */
+static DEFINE_SPINLOCK(hwspinlock_tree_lock);
+
+/**
+ * __hwspin_trylock() - attempt to lock a specific hwspinlock
+ * @hwlock: an hwspinlock which we want to trylock
+ * @mode: controls whether local interrupts are disabled or not
+ * @flags: a pointer where the caller's interrupt state will be saved at (if
+ * requested)
+ *
+ * This function attempts to lock an hwspinlock, and will immediately
+ * fail if the hwspinlock is already taken.
+ *
+ * Upon a successful return from this function, preemption (and possibly
+ * interrupts) is disabled, so the caller must not sleep, and is advised to
+ * release the hwspinlock as soon as possible. This is required in order to
+ * minimize remote cores polling on the hardware interconnect.
+ *
+ * The user decides whether local interrupts are disabled or not, and if yes,
+ * whether he wants their previous state to be saved. It is up to the user
+ * to choose the appropriate @mode of operation, exactly the same way users
+ * should decide between spin_trylock, spin_trylock_irq and
+ * spin_trylock_irqsave.
+ *
+ * Returns 0 if we successfully locked the hwspinlock or -EBUSY if
+ * the hwspinlock was already taken.
+ * This function will never sleep.
+ */
+int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ int ret;
+
+ BUG_ON(!hwlock);
+ BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
+
+ /*
+ * This spin_lock{_irq, _irqsave} serves three purposes:
+ *
+ * 1. Disable preemption, in order to minimize the period of time
+ * in which the hwspinlock is taken. This is important in order
+ * to minimize the possible polling on the hardware interconnect
+ * by a remote user of this lock.
+ * 2. Make the hwspinlock SMP-safe (so we can take it from
+ * additional contexts on the local host).
+ * 3. Ensure that in_atomic/might_sleep checks catch potential
+ * problems with hwspinlock usage (e.g. scheduler checks like
+ * 'scheduling while atomic' etc.)
+ */
+ if (mode == HWLOCK_IRQSTATE)
+ ret = spin_trylock_irqsave(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ ret = spin_trylock_irq(&hwlock->lock);
+ else
+ ret = spin_trylock(&hwlock->lock);
+
+ /* is lock already taken by another context on the local cpu ? */
+ if (!ret)
+ return -EBUSY;
+
+ /* try to take the hwspinlock device */
+ ret = hwlock->ops->trylock(hwlock);
+
+ /* if hwlock is already taken, undo spin_trylock_* and exit */
+ if (!ret) {
+ if (mode == HWLOCK_IRQSTATE)
+ spin_unlock_irqrestore(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ spin_unlock_irq(&hwlock->lock);
+ else
+ spin_unlock(&hwlock->lock);
+
+ return -EBUSY;
+ }
+
+ /*
+ * We can be sure the other core's memory operations
+ * are observable to us only _after_ we successfully take
+ * the hwspinlock, and we must make sure that subsequent memory
+ * operations (both reads and writes) will not be reordered before
+ * we actually took the hwspinlock.
+ *
+ * Note: the implicit memory barrier of the spinlock above is too
+ * early, so we need this additional explicit memory barrier.
+ */
+ mb();
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__hwspin_trylock);
+
+/**
+ * __hwspin_lock_timeout() - lock an hwspinlock with timeout limit
+ * @hwlock: the hwspinlock to be locked
+ * @timeout: timeout value in jiffies
+ * @mode: mode which controls whether local interrupts are disabled or not
+ * @flags: a pointer to where the caller's interrupt state will be saved at (if
+ * requested)
+ *
+ * This function locks the given @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption is disabled
+ * (and possibly local interrupts, too), so the caller must not sleep,
+ * and is advised to release the hwspinlock as soon as possible.
+ * This is required in order to minimize remote cores polling on the
+ * hardware interconnect.
+ *
+ * The user decides whether local interrupts are disabled or not, and if yes,
+ * whether he wants their previous state to be saved. It is up to the user
+ * to choose the appropriate @mode of operation, exactly the same way users
+ * should decide between spin_lock, spin_lock_irq and spin_lock_irqsave.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+int __hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to,
+ int mode, unsigned long *flags)
+{
+ int ret;
+ unsigned long expire;
+
+ if (to < 0) {
+ dev_err(hwlock->dev, "%s: wrong timeout value %lx\n",
+ __func__, to);
+ return -EINVAL;
+ }
+
+ expire = to + jiffies;
+
+ for (;;) {
+ /* Try to take the hwspinlock */
+ ret = __hwspin_trylock(hwlock, mode, flags);
+ if (ret != -EBUSY)
+ break;
+
+ /*
+ * The lock is already taken, let's check if the user wants
+ * us to try again
+ */
+ if (to != MAX_SCHEDULE_TIMEOUT &&
+ time_is_before_eq_jiffies(expire))
+ return -ETIMEDOUT;
+
+ /*
+ * Allow platform-specific relax handlers to prevent
+ * hogging the interconnect (no sleeping, though)
+ */
+ if (hwlock->ops->relax)
+ hwlock->ops->relax(hwlock);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__hwspin_lock_timeout);
+
+/**
+ * __hwspin_unlock() - unlock a specific hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ * @mode: controls whether local interrupts needs to be restored or not
+ * @flags: previous caller's interrupt state to restore (if requested)
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * (possibly) enable interrupts or restore their previous state.
+ * @hwlock must be already locked before calling this function: it is a bug
+ * to call unlock on a @hwlock that is already unlocked.
+ *
+ * The user decides whether local interrupts should be enabled or not, and
+ * if yes, whether he wants their previous state to be restored. It is up
+ * to the user to choose the appropriate @mode of operation, exactly the
+ * same way users decide between spin_unlock, spin_unlock_irq and
+ * spin_unlock_irqrestore.
+ *
+ * The function will never sleep.
+ */
+void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ BUG_ON(!hwlock);
+ BUG_ON(!flags && mode == HWLOCK_IRQSTATE);
+
+ /*
+ * We must make sure that memory operations (both reads and writes),
+ * done before unlocking the hwspinlock, will not be reordered
+ * after the lock is released.
+ *
+ * That's the purpose of this explicit memory barrier.
+ *
+ * Note: the memory barrier induced by the spin_unlock below is too
+ * late; the other core is going to access memory soon after it will
+ * take the hwspinlock, and by then we want to be sure our memory
+ * operations are already observable.
+ */
+ mb();
+
+ hwlock->ops->unlock(hwlock);
+
+ /* Undo the spin_trylock{_irq, _irqsave} called while locking */
+ if (mode == HWLOCK_IRQSTATE)
+ spin_unlock_irqrestore(&hwlock->lock, *flags);
+ else if (mode == HWLOCK_IRQ)
+ spin_unlock_irq(&hwlock->lock);
+ else
+ spin_unlock(&hwlock->lock);
+}
+EXPORT_SYMBOL_GPL(__hwspin_unlock);
+
+/**
+ * hwspin_lock_register() - register a new hw spinlock
+ * @hwlock: hwspinlock to register.
+ *
+ * This function should be called from the underlying platform-specific
+ * implementation, to register a new hwspinlock instance.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context.
+ *
+ * Returns 0 on success, or an appropriate error code on failure
+ */
+int hwspin_lock_register(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ if (!hwlock || !hwlock->ops ||
+ !hwlock->ops->trylock || !hwlock->ops->unlock) {
+ pr_err("invalid parameters\n");
+ return -EINVAL;
+ }
+
+ spin_lock_init(&hwlock->lock);
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ ret = radix_tree_insert(&hwspinlock_tree, hwlock->id, hwlock);
+ if (ret)
+ goto out;
+
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* self-sanity check which should never fail */
+ WARN_ON(tmp != hwlock);
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_register);
+
+/**
+ * hwspin_lock_unregister() - unregister an hw spinlock
+ * @id: index of the specific hwspinlock to unregister
+ *
+ * This function should be called from the underlying platform-specific
+ * implementation, to unregister an existing (and unused) hwspinlock.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context.
+ *
+ * Returns the address of hwspinlock @id on success, or NULL on failure
+ */
+struct hwspinlock *hwspin_lock_unregister(unsigned int id)
+{
+ struct hwspinlock *hwlock = NULL;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure the hwspinlock is not in use (tag is set) */
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_err("hwspinlock %d still in use (or not present)\n", id);
+ goto out;
+ }
+
+ hwlock = radix_tree_delete(&hwspinlock_tree, id);
+ if (!hwlock) {
+ pr_err("failed to delete hwspinlock %d\n", id);
+ goto out;
+ }
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
+
+/**
+ * __hwspin_lock_request() - tag an hwspinlock as used and power it up
+ *
+ * This is an internal function that prepares an hwspinlock instance
+ * before it is given to the user. The function assumes that
+ * hwspinlock_tree_lock is taken.
+ *
+ * Returns 0 or positive to indicate success, and a negative value to
+ * indicate an error (with the appropriate error code)
+ */
+static int __hwspin_lock_request(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ /* prevent underlying implementation from being removed */
+ if (!try_module_get(hwlock->owner)) {
+ dev_err(hwlock->dev, "%s: can't get owner\n", __func__);
+ return -EINVAL;
+ }
+
+ /* notify PM core that power is now needed */
+ ret = pm_runtime_get_sync(hwlock->dev);
+ if (ret < 0) {
+ dev_err(hwlock->dev, "%s: can't power on device\n", __func__);
+ return ret;
+ }
+
+ /* mark hwspinlock as used, should not fail */
+ tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* self-sanity check that should never fail */
+ WARN_ON(tmp != hwlock);
+
+ return ret;
+}
+
+/**
+ * hwspin_lock_get_id() - retrieve id number of a given hwspinlock
+ * @hwlock: a valid hwspinlock instance
+ *
+ * Returns the id number of a given @hwlock, or -EINVAL if @hwlock is invalid.
+ */
+int hwspin_lock_get_id(struct hwspinlock *hwlock)
+{
+ if (!hwlock) {
+ pr_err("invalid hwlock\n");
+ return -EINVAL;
+ }
+
+ return hwlock->id;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
+
+/**
+ * hwspin_lock_request() - request an hwspinlock
+ *
+ * This function should be called by users of the hwspinlock device,
+ * in order to dynamically assign them an unused hwspinlock.
+ * Usually the user of this lock will then have to communicate the lock's id
+ * to the remote core before it can be used for synchronization (to get the
+ * id of a given hwlock, use hwspin_lock_get_id()).
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns the address of the assigned hwspinlock, or NULL on error
+ */
+struct hwspinlock *hwspin_lock_request(void)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* look for an unused lock */
+ ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
+ 0, 1, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_warn("a free hwspinlock is not available\n");
+ hwlock = NULL;
+ goto out;
+ }
+
+ /* sanity check that should never fail */
+ WARN_ON(ret > 1);
+
+ /* mark as used and power up */
+ ret = __hwspin_lock_request(hwlock);
+ if (ret < 0)
+ hwlock = NULL;
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_request);
+
+/**
+ * hwspin_lock_request_specific() - request for a specific hwspinlock
+ * @id: index of the specific hwspinlock that is requested
+ *
+ * This function should be called by users of the hwspinlock module,
+ * in order to assign them a specific hwspinlock.
+ * Usually early board code will be calling this function in order to
+ * reserve specific hwspinlock ids for predefined purposes.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns the address of the assigned hwspinlock, or NULL on error
+ */
+struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
+{
+ struct hwspinlock *hwlock;
+ int ret;
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure this hwspinlock exists */
+ hwlock = radix_tree_lookup(&hwspinlock_tree, id);
+ if (!hwlock) {
+ pr_warn("hwspinlock %u does not exist\n", id);
+ goto out;
+ }
+
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(hwlock->id != id);
+
+ /* make sure this hwspinlock is unused */
+ ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
+ if (ret == 0) {
+ pr_warn("hwspinlock %u is already in use\n", id);
+ hwlock = NULL;
+ goto out;
+ }
+
+ /* mark as used and power up */
+ ret = __hwspin_lock_request(hwlock);
+ if (ret < 0)
+ hwlock = NULL;
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return hwlock;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
+
+/**
+ * hwspin_lock_free() - free a specific hwspinlock
+ * @hwlock: the specific hwspinlock to free
+ *
+ * This function mark @hwlock as free again.
+ * Should only be called with an @hwlock that was retrieved from
+ * an earlier call to omap_hwspin_lock_request{_specific}.
+ *
+ * Can be called from an atomic context (will not sleep) but not from
+ * within interrupt context (simply because there is no use case for
+ * that yet).
+ *
+ * Returns 0 on success, or an appropriate error code on failure
+ */
+int hwspin_lock_free(struct hwspinlock *hwlock)
+{
+ struct hwspinlock *tmp;
+ int ret;
+
+ if (!hwlock) {
+ pr_err("invalid hwlock\n");
+ return -EINVAL;
+ }
+
+ spin_lock(&hwspinlock_tree_lock);
+
+ /* make sure the hwspinlock is used */
+ ret = radix_tree_tag_get(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+ if (ret == 1) {
+ dev_err(hwlock->dev, "%s: hwlock is already free\n", __func__);
+ dump_stack();
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* notify the underlying device that power is not needed */
+ ret = pm_runtime_put(hwlock->dev);
+ if (ret < 0)
+ goto out;
+
+ /* mark this hwspinlock as available */
+ tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock->id,
+ HWSPINLOCK_UNUSED);
+
+ /* sanity check (this shouldn't happen) */
+ WARN_ON(tmp != hwlock);
+
+ module_put(hwlock->owner);
+
+out:
+ spin_unlock(&hwspinlock_tree_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hwspin_lock_free);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock interface");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
diff --git a/include/linux/hwspinlock.h b/include/linux/hwspinlock.h
new file mode 100644
index 0000000..47a6b1c
--- /dev/null
+++ b/include/linux/hwspinlock.h
@@ -0,0 +1,298 @@
+/*
+ * Hardware spinlock public header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_HWSPINLOCK_H
+#define __LINUX_HWSPINLOCK_H
+
+#include <linux/err.h>
+#include <linux/sched.h>
+
+/* hwspinlock mode argument */
+#define HWLOCK_IRQSTATE 0x01 /* Disable interrupts, save state */
+#define HWLOCK_IRQ 0x02 /* Disable interrupts, don't save state */
+
+struct hwspinlock;
+
+#if defined(CONFIG_HWSPINLOCK) || defined(CONFIG_HWSPINLOCK_MODULE)
+
+int hwspin_lock_register(struct hwspinlock *lock);
+struct hwspinlock *hwspin_lock_unregister(unsigned int id);
+struct hwspinlock *hwspin_lock_request(void);
+struct hwspinlock *hwspin_lock_request_specific(unsigned int id);
+int hwspin_lock_free(struct hwspinlock *hwlock);
+int hwspin_lock_get_id(struct hwspinlock *hwlock);
+int __hwspin_lock_timeout(struct hwspinlock *, signed long, int,
+ unsigned long *);
+int __hwspin_trylock(struct hwspinlock *, int, unsigned long *);
+void __hwspin_unlock(struct hwspinlock *, int, unsigned long *);
+
+#else /* !CONFIG_HWSPINLOCK */
+
+/*
+ * We don't want these functions to fail if CONFIG_HWSPINLOCK is not
+ * enabled. We prefer to silently succeed in this case, and let the
+ * code path get compiled away. This way, if CONFIG_HWSPINLOCK is not
+ * required on a given setup, users will still work.
+ *
+ * The only exception is hwspin_lock_register/hwspin_lock_unregister, with which
+ * we _do_ want users to fail (no point in registering hwspinlock instances if
+ * the framework is not available).
+ *
+ * Note: ERR_PTR(-ENODEV) will still be considered a success for NULL-checking
+ * users. Others, which care, can still check this with IS_ERR.
+ */
+static inline struct hwspinlock *hwspin_lock_request(void)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline int hwspin_lock_free(struct hwspinlock *hwlock)
+{
+ return 0;
+}
+
+static inline
+int __hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to,
+ int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline
+int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline
+void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
+{
+ return 0;
+}
+
+static inline int hwspin_lock_get_id(struct hwspinlock *hwlock)
+{
+ return 0;
+}
+
+static inline int hwspin_lock_register(struct hwspinlock *hwlock)
+{
+ return -ENODEV;
+}
+
+static inline struct hwspinlock *hwspin_lock_unregister(unsigned int id)
+{
+ return NULL;
+}
+
+#endif /* !CONFIG_HWSPINLOCK */
+
+/**
+ * hwspin_trylock_irqsave() - try to lock an hwspinlock, disable interrupts
+ * @hwlock: an hwspinlock which we want to trylock
+ * @flags: a pointer to where the caller's interrupt state will be saved at
+ *
+ * This function attempts to lock the underlying hwspinlock, and will
+ * immediately fail if the hwspinlock is already locked.
+ *
+ * Upon a successful return from this function, preemption and local
+ * interrupts are disabled (previous interrupts state is saved at @flags),
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline
+int hwspin_trylock_irqsave(struct hwspinlock *hwlock, unsigned long *flags)
+{
+ return __hwspin_trylock(hwlock, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_trylock_irq() - try to lock an hwspinlock, disable interrupts
+ * @hwlock: an hwspinlock which we want to trylock
+ *
+ * This function attempts to lock the underlying hwspinlock, and will
+ * immediately fail if the hwspinlock is already locked.
+ *
+ * Upon a successful return from this function, preemption and local
+ * interrupts are disabled, so the caller must not sleep, and is advised
+ * to release the hwspinlock as soon as possible.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline int hwspin_trylock_irq(struct hwspinlock *hwlock)
+{
+ return __hwspin_trylock(hwlock, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_trylock() - attempt to lock a specific hwspinlock
+ * @hwlock: an hwspinlock which we want to trylock
+ *
+ * This function attempts to lock an hwspinlock, and will immediately fail
+ * if the hwspinlock is already taken.
+ *
+ * Upon a successful return from this function, preemption is disabled,
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible. This is required in order to minimize remote cores
+ * polling on the hardware interconnect.
+ *
+ * Returns 0 if we successfully locked the hwspinlock, -EBUSY if
+ * the hwspinlock was already taken, and -EINVAL if @hwlock is invalid.
+ */
+static inline int hwspin_trylock(struct hwspinlock *hwlock)
+{
+ return __hwspin_trylock(hwlock, 0, NULL);
+}
+
+/**
+ * hwspin_lock_timeout_irqsave() - lock hwspinlock, with timeout, disable irqs
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ * @flags: a pointer to where the caller's interrupt state will be saved at
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption and local interrupts
+ * are disabled (plus previous interrupt state is saved), so the caller must
+ * not sleep, and is advised to release the hwspinlock as soon as possible.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline int hwspin_lock_timeout_irqsave(struct hwspinlock *hwlock,
+ signed long to, unsigned long *flags)
+{
+ return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_lock_timeout_irq() - lock hwspinlock, with timeout, disable irqs
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption and local interrupts
+ * are disabled so the caller must not sleep, and is advised to release the
+ * hwspinlock as soon as possible.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline
+int hwspin_lock_timeout_irq(struct hwspinlock *hwlock, signed long to)
+{
+ return __hwspin_lock_timeout(hwlock, to, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_lock_timeout() - lock an hwspinlock with timeout limit
+ * @hwlock: the hwspinlock to be locked
+ * @to: timeout value in jiffies
+ *
+ * This function locks the underlying @hwlock. If the @hwlock
+ * is already taken, the function will busy loop waiting for it to
+ * be released, but give up when @timeout jiffies have elapsed. If @timeout
+ * is %MAX_SCHEDULE_TIMEOUT, the function will never give up (therefore if a
+ * faulty remote core never releases the @hwlock, it will deadlock).
+ *
+ * Upon a successful return from this function, preemption is disabled
+ * so the caller must not sleep, and is advised to release the hwspinlock
+ * as soon as possible.
+ * This is required in order to minimize remote cores polling on the
+ * hardware interconnect.
+ *
+ * Returns 0 when the @hwlock was successfully taken, and an appropriate
+ * error code otherwise (most notably an -ETIMEDOUT if the @hwlock is still
+ * busy after @timeout meets jiffies). The function will never sleep.
+ */
+static inline
+int hwspin_lock_timeout(struct hwspinlock *hwlock, signed long to)
+{
+ return __hwspin_lock_timeout(hwlock, to, 0, NULL);
+}
+
+/**
+ * hwspin_unlock_irqrestore() - unlock hwspinlock, restore irq state
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ * @flags: previous caller's interrupt state to restore
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * restore the previous state of the local interrupts. It should be used
+ * to undo, e.g., hwspin_trylock_irqsave().
+ *
+ * @hwlock must be already locked before calling this function: it is a bug
+ * to call unlock on a @hwlock that is already unlocked.
+ */
+static inline void hwspin_unlock_irqrestore(struct hwspinlock *hwlock,
+ unsigned long *flags)
+{
+ __hwspin_unlock(hwlock, HWLOCK_IRQSTATE, flags);
+}
+
+/**
+ * hwspin_unlock_irq() - unlock hwspinlock, enable interrupts
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ *
+ * This function will unlock a specific hwspinlock, enable preemption and
+ * enable local interrupts. Should be used to undo hwspin_lock_irq().
+ *
+ * @hwlock must be already locked (e.g. by hwspin_trylock_irq()) before
+ * calling this function: it is a bug to call unlock on a @hwlock that is
+ * already unlocked.
+ */
+static inline void hwspin_unlock_irq(struct hwspinlock *hwlock)
+{
+ __hwspin_unlock(hwlock, HWLOCK_IRQ, NULL);
+}
+
+/**
+ * hwspin_unlock() - unlock hwspinlock
+ * @hwlock: a previously-acquired hwspinlock which we want to unlock
+ *
+ * This function will unlock a specific hwspinlock and enable preemption
+ * back.
+ *
+ * @hwlock must be already locked (e.g. by hwspin_trylock()) before calling
+ * this function: it is a bug to call unlock on a @hwlock that is already
+ * unlocked.
+ */
+static inline void hwspin_unlock(struct hwspinlock *hwlock)
+{
+ __hwspin_unlock(hwlock, 0, NULL);
+}
+
+#endif /* __LINUX_HWSPINLOCK_H */
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 2/4] drivers: hwspinlock: add OMAP implementation
2010-12-03 23:50 ` Ohad Ben-Cohen
(?)
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann,
Simon Que, Krishnamoorthy, Balaji T
From: Simon Que <sque@ti.com>
Add hwspinlock support for the OMAP4 Hardware Spinlock device.
The Hardware Spinlock device on OMAP4 provides hardware assistance
for synchronization between the multiple processors in the system
(dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
[ohad@wizery.com: adapt to hwspinlock framework, tidy up]
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Krishnamoorthy, Balaji T <balajitk@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
drivers/hwspinlock/Kconfig | 9 ++
drivers/hwspinlock/Makefile | 1 +
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++++++++++++++++++++++++
3 files changed, 241 insertions(+), 0 deletions(-)
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
index 9dd8db4..eb4af28 100644
--- a/drivers/hwspinlock/Kconfig
+++ b/drivers/hwspinlock/Kconfig
@@ -11,3 +11,12 @@ config HWSPINLOCK
coprocessors).
If unsure, say N.
+
+config HWSPINLOCK_OMAP
+ tristate "OMAP Hardware Spinlock device"
+ depends on HWSPINLOCK && ARCH_OMAP4
+ help
+ Say y here to support the OMAP Hardware Spinlock device (firstly
+ introduced in OMAP4).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
index b9d2b9f..5729a3f 100644
--- a/drivers/hwspinlock/Makefile
+++ b/drivers/hwspinlock/Makefile
@@ -3,3 +3,4 @@
#
obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
+obj-$(CONFIG_HWSPINLOCK_OMAP) += omap_hwspinlock.o
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c
new file mode 100644
index 0000000..b5867e1
--- /dev/null
+++ b/drivers/hwspinlock/omap_hwspinlock.c
@@ -0,0 +1,231 @@
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ * Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/hwspinlock.h>
+#include <linux/platform_device.h>
+
+#include "hwspinlock.h"
+
+/* Spinlock register offsets */
+#define SYSSTATUS_OFFSET 0x0014
+#define LOCK_BASE_OFFSET 0x0800
+
+#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
+
+/* Possible values of SPINLOCK_LOCK_REG */
+#define SPINLOCK_NOTTAKEN (0) /* free */
+#define SPINLOCK_TAKEN (1) /* locked */
+
+#define to_omap_hwspinlock(lock) \
+ container_of(lock, struct omap_hwspinlock, lock)
+
+struct omap_hwspinlock {
+ struct hwspinlock lock;
+ void __iomem *addr;
+};
+
+struct omap_hwspinlock_state {
+ int num_locks; /* Total number of locks in system */
+ void __iomem *io_base; /* Mapped base address */
+};
+
+static int omap_hwspinlock_trylock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* attempt to acquire the lock by reading its value */
+ return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
+}
+
+static void omap_hwspinlock_unlock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* release the lock by writing 0 to it */
+ writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
+}
+
+/*
+ * relax the OMAP interconnect while spinning on it.
+ *
+ * The specs recommended that the retry delay time will be
+ * just over half of the time that a requester would be
+ * expected to hold the lock.
+ *
+ * The number below is taken from an hardware specs example,
+ * obviously it is somewhat arbitrary.
+ */
+static void omap_hwspinlock_relax(struct hwspinlock *lock)
+{
+ ndelay(50);
+}
+
+static const struct hwspinlock_ops omap_hwspinlock_ops = {
+ .trylock = omap_hwspinlock_trylock,
+ .unlock = omap_hwspinlock_unlock,
+ .relax = omap_hwspinlock_relax,
+};
+
+static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
+{
+ struct omap_hwspinlock *omap_lock;
+ struct omap_hwspinlock_state *state;
+ struct hwspinlock *lock;
+ struct resource *res;
+ void __iomem *io_base;
+ int i, ret;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ state = kzalloc(sizeof(*state), GFP_KERNEL);
+ if (!state)
+ return -ENOMEM;
+
+ io_base = ioremap(res->start, resource_size(res));
+ if (!io_base) {
+ ret = -ENOMEM;
+ goto free_state;
+ }
+
+ /* Determine number of locks */
+ i = readl(io_base + SYSSTATUS_OFFSET);
+ i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
+
+ /* exactly one of the four least significant bits must be 1 */
+ if (!i || !is_power_of_2(i) || i > 8) {
+ ret = -EINVAL;
+ goto iounmap_base;
+ }
+
+ state->num_locks = i * 32;
+ state->io_base = io_base;
+
+ platform_set_drvdata(pdev, state);
+
+ /*
+ * runtime PM will make sure the clock of this module is
+ * enabled iff at least one lock is requested
+ */
+ pm_runtime_enable(&pdev->dev);
+
+ for (i = 0; i < state->num_locks; i++) {
+ omap_lock = kzalloc(sizeof(*omap_lock), GFP_KERNEL);
+ if (!omap_lock) {
+ ret = -ENOMEM;
+ goto free_locks;
+ }
+
+ omap_lock->lock.dev = &pdev->dev;
+ omap_lock->lock.owner = THIS_MODULE;
+ omap_lock->lock.id = i;
+ omap_lock->lock.ops = &omap_hwspinlock_ops;
+ omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
+
+ ret = hwspin_lock_register(&omap_lock->lock);
+ if (ret) {
+ kfree(omap_lock);
+ goto free_locks;
+ }
+ }
+
+ return 0;
+
+free_locks:
+ while (--i >= 0) {
+ lock = hwspin_lock_unregister(i);
+ /* this should't happen, but let's give our best effort */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
+ continue;
+ }
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+ pm_runtime_disable(&pdev->dev);
+iounmap_base:
+ iounmap(io_base);
+free_state:
+ kfree(state);
+ return ret;
+}
+
+static int omap_hwspinlock_remove(struct platform_device *pdev)
+{
+ struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
+ struct hwspinlock *lock;
+ struct omap_hwspinlock *omap_lock;
+ int i;
+
+ for (i = 0; i < state->num_locks; i++) {
+ lock = hwspin_lock_unregister(i);
+ /* this shouldn't happen at this point. if it does, at least
+ * don't continue with the remove */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
+ return -EBUSY;
+ }
+
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+
+ pm_runtime_disable(&pdev->dev);
+ iounmap(state->io_base);
+ kfree(state);
+
+ return 0;
+}
+
+static struct platform_driver omap_hwspinlock_driver = {
+ .probe = omap_hwspinlock_probe,
+ .remove = omap_hwspinlock_remove,
+ .driver = {
+ .name = "omap_hwspinlock",
+ },
+};
+
+static int __init omap_hwspinlock_init(void)
+{
+ return platform_driver_register(&omap_hwspinlock_driver);
+}
+/* board init code might need to reserve hwspinlocks for predefined purposes */
+postcore_initcall(omap_hwspinlock_init);
+
+static void __exit omap_hwspinlock_exit(void)
+{
+ platform_driver_unregister(&omap_hwspinlock_driver);
+}
+module_exit(omap_hwspinlock_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
+MODULE_AUTHOR("Simon Que <sque@ti.com>");
+MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 2/4] drivers: hwspinlock: add OMAP implementation
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann,
Simon Que, Krishnamoorthy, Balaji T
From: Simon Que <sque@ti.com>
Add hwspinlock support for the OMAP4 Hardware Spinlock device.
The Hardware Spinlock device on OMAP4 provides hardware assistance
for synchronization between the multiple processors in the system
(dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
[ohad@wizery.com: adapt to hwspinlock framework, tidy up]
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Krishnamoorthy, Balaji T <balajitk@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
drivers/hwspinlock/Kconfig | 9 ++
drivers/hwspinlock/Makefile | 1 +
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++++++++++++++++++++++++
3 files changed, 241 insertions(+), 0 deletions(-)
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
index 9dd8db4..eb4af28 100644
--- a/drivers/hwspinlock/Kconfig
+++ b/drivers/hwspinlock/Kconfig
@@ -11,3 +11,12 @@ config HWSPINLOCK
coprocessors).
If unsure, say N.
+
+config HWSPINLOCK_OMAP
+ tristate "OMAP Hardware Spinlock device"
+ depends on HWSPINLOCK && ARCH_OMAP4
+ help
+ Say y here to support the OMAP Hardware Spinlock device (firstly
+ introduced in OMAP4).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
index b9d2b9f..5729a3f 100644
--- a/drivers/hwspinlock/Makefile
+++ b/drivers/hwspinlock/Makefile
@@ -3,3 +3,4 @@
#
obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
+obj-$(CONFIG_HWSPINLOCK_OMAP) += omap_hwspinlock.o
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c
new file mode 100644
index 0000000..b5867e1
--- /dev/null
+++ b/drivers/hwspinlock/omap_hwspinlock.c
@@ -0,0 +1,231 @@
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ * Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/hwspinlock.h>
+#include <linux/platform_device.h>
+
+#include "hwspinlock.h"
+
+/* Spinlock register offsets */
+#define SYSSTATUS_OFFSET 0x0014
+#define LOCK_BASE_OFFSET 0x0800
+
+#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
+
+/* Possible values of SPINLOCK_LOCK_REG */
+#define SPINLOCK_NOTTAKEN (0) /* free */
+#define SPINLOCK_TAKEN (1) /* locked */
+
+#define to_omap_hwspinlock(lock) \
+ container_of(lock, struct omap_hwspinlock, lock)
+
+struct omap_hwspinlock {
+ struct hwspinlock lock;
+ void __iomem *addr;
+};
+
+struct omap_hwspinlock_state {
+ int num_locks; /* Total number of locks in system */
+ void __iomem *io_base; /* Mapped base address */
+};
+
+static int omap_hwspinlock_trylock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* attempt to acquire the lock by reading its value */
+ return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
+}
+
+static void omap_hwspinlock_unlock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* release the lock by writing 0 to it */
+ writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
+}
+
+/*
+ * relax the OMAP interconnect while spinning on it.
+ *
+ * The specs recommended that the retry delay time will be
+ * just over half of the time that a requester would be
+ * expected to hold the lock.
+ *
+ * The number below is taken from an hardware specs example,
+ * obviously it is somewhat arbitrary.
+ */
+static void omap_hwspinlock_relax(struct hwspinlock *lock)
+{
+ ndelay(50);
+}
+
+static const struct hwspinlock_ops omap_hwspinlock_ops = {
+ .trylock = omap_hwspinlock_trylock,
+ .unlock = omap_hwspinlock_unlock,
+ .relax = omap_hwspinlock_relax,
+};
+
+static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
+{
+ struct omap_hwspinlock *omap_lock;
+ struct omap_hwspinlock_state *state;
+ struct hwspinlock *lock;
+ struct resource *res;
+ void __iomem *io_base;
+ int i, ret;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ state = kzalloc(sizeof(*state), GFP_KERNEL);
+ if (!state)
+ return -ENOMEM;
+
+ io_base = ioremap(res->start, resource_size(res));
+ if (!io_base) {
+ ret = -ENOMEM;
+ goto free_state;
+ }
+
+ /* Determine number of locks */
+ i = readl(io_base + SYSSTATUS_OFFSET);
+ i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
+
+ /* exactly one of the four least significant bits must be 1 */
+ if (!i || !is_power_of_2(i) || i > 8) {
+ ret = -EINVAL;
+ goto iounmap_base;
+ }
+
+ state->num_locks = i * 32;
+ state->io_base = io_base;
+
+ platform_set_drvdata(pdev, state);
+
+ /*
+ * runtime PM will make sure the clock of this module is
+ * enabled iff at least one lock is requested
+ */
+ pm_runtime_enable(&pdev->dev);
+
+ for (i = 0; i < state->num_locks; i++) {
+ omap_lock = kzalloc(sizeof(*omap_lock), GFP_KERNEL);
+ if (!omap_lock) {
+ ret = -ENOMEM;
+ goto free_locks;
+ }
+
+ omap_lock->lock.dev = &pdev->dev;
+ omap_lock->lock.owner = THIS_MODULE;
+ omap_lock->lock.id = i;
+ omap_lock->lock.ops = &omap_hwspinlock_ops;
+ omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
+
+ ret = hwspin_lock_register(&omap_lock->lock);
+ if (ret) {
+ kfree(omap_lock);
+ goto free_locks;
+ }
+ }
+
+ return 0;
+
+free_locks:
+ while (--i >= 0) {
+ lock = hwspin_lock_unregister(i);
+ /* this should't happen, but let's give our best effort */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
+ continue;
+ }
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+ pm_runtime_disable(&pdev->dev);
+iounmap_base:
+ iounmap(io_base);
+free_state:
+ kfree(state);
+ return ret;
+}
+
+static int omap_hwspinlock_remove(struct platform_device *pdev)
+{
+ struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
+ struct hwspinlock *lock;
+ struct omap_hwspinlock *omap_lock;
+ int i;
+
+ for (i = 0; i < state->num_locks; i++) {
+ lock = hwspin_lock_unregister(i);
+ /* this shouldn't happen at this point. if it does, at least
+ * don't continue with the remove */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
+ return -EBUSY;
+ }
+
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+
+ pm_runtime_disable(&pdev->dev);
+ iounmap(state->io_base);
+ kfree(state);
+
+ return 0;
+}
+
+static struct platform_driver omap_hwspinlock_driver = {
+ .probe = omap_hwspinlock_probe,
+ .remove = omap_hwspinlock_remove,
+ .driver = {
+ .name = "omap_hwspinlock",
+ },
+};
+
+static int __init omap_hwspinlock_init(void)
+{
+ return platform_driver_register(&omap_hwspinlock_driver);
+}
+/* board init code might need to reserve hwspinlocks for predefined purposes */
+postcore_initcall(omap_hwspinlock_init);
+
+static void __exit omap_hwspinlock_exit(void)
+{
+ platform_driver_unregister(&omap_hwspinlock_driver);
+}
+module_exit(omap_hwspinlock_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
+MODULE_AUTHOR("Simon Que <sque@ti.com>");
+MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 2/4] drivers: hwspinlock: add OMAP implementation
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-arm-kernel
From: Simon Que <sque@ti.com>
Add hwspinlock support for the OMAP4 Hardware Spinlock device.
The Hardware Spinlock device on OMAP4 provides hardware assistance
for synchronization between the multiple processors in the system
(dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
[ohad at wizery.com: adapt to hwspinlock framework, tidy up]
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Krishnamoorthy, Balaji T <balajitk@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
drivers/hwspinlock/Kconfig | 9 ++
drivers/hwspinlock/Makefile | 1 +
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++++++++++++++++++++++++
3 files changed, 241 insertions(+), 0 deletions(-)
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
index 9dd8db4..eb4af28 100644
--- a/drivers/hwspinlock/Kconfig
+++ b/drivers/hwspinlock/Kconfig
@@ -11,3 +11,12 @@ config HWSPINLOCK
coprocessors).
If unsure, say N.
+
+config HWSPINLOCK_OMAP
+ tristate "OMAP Hardware Spinlock device"
+ depends on HWSPINLOCK && ARCH_OMAP4
+ help
+ Say y here to support the OMAP Hardware Spinlock device (firstly
+ introduced in OMAP4).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
index b9d2b9f..5729a3f 100644
--- a/drivers/hwspinlock/Makefile
+++ b/drivers/hwspinlock/Makefile
@@ -3,3 +3,4 @@
#
obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
+obj-$(CONFIG_HWSPINLOCK_OMAP) += omap_hwspinlock.o
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c
new file mode 100644
index 0000000..b5867e1
--- /dev/null
+++ b/drivers/hwspinlock/omap_hwspinlock.c
@@ -0,0 +1,231 @@
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ * Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/hwspinlock.h>
+#include <linux/platform_device.h>
+
+#include "hwspinlock.h"
+
+/* Spinlock register offsets */
+#define SYSSTATUS_OFFSET 0x0014
+#define LOCK_BASE_OFFSET 0x0800
+
+#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
+
+/* Possible values of SPINLOCK_LOCK_REG */
+#define SPINLOCK_NOTTAKEN (0) /* free */
+#define SPINLOCK_TAKEN (1) /* locked */
+
+#define to_omap_hwspinlock(lock) \
+ container_of(lock, struct omap_hwspinlock, lock)
+
+struct omap_hwspinlock {
+ struct hwspinlock lock;
+ void __iomem *addr;
+};
+
+struct omap_hwspinlock_state {
+ int num_locks; /* Total number of locks in system */
+ void __iomem *io_base; /* Mapped base address */
+};
+
+static int omap_hwspinlock_trylock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* attempt to acquire the lock by reading its value */
+ return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
+}
+
+static void omap_hwspinlock_unlock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* release the lock by writing 0 to it */
+ writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
+}
+
+/*
+ * relax the OMAP interconnect while spinning on it.
+ *
+ * The specs recommended that the retry delay time will be
+ * just over half of the time that a requester would be
+ * expected to hold the lock.
+ *
+ * The number below is taken from an hardware specs example,
+ * obviously it is somewhat arbitrary.
+ */
+static void omap_hwspinlock_relax(struct hwspinlock *lock)
+{
+ ndelay(50);
+}
+
+static const struct hwspinlock_ops omap_hwspinlock_ops = {
+ .trylock = omap_hwspinlock_trylock,
+ .unlock = omap_hwspinlock_unlock,
+ .relax = omap_hwspinlock_relax,
+};
+
+static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
+{
+ struct omap_hwspinlock *omap_lock;
+ struct omap_hwspinlock_state *state;
+ struct hwspinlock *lock;
+ struct resource *res;
+ void __iomem *io_base;
+ int i, ret;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ state = kzalloc(sizeof(*state), GFP_KERNEL);
+ if (!state)
+ return -ENOMEM;
+
+ io_base = ioremap(res->start, resource_size(res));
+ if (!io_base) {
+ ret = -ENOMEM;
+ goto free_state;
+ }
+
+ /* Determine number of locks */
+ i = readl(io_base + SYSSTATUS_OFFSET);
+ i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
+
+ /* exactly one of the four least significant bits must be 1 */
+ if (!i || !is_power_of_2(i) || i > 8) {
+ ret = -EINVAL;
+ goto iounmap_base;
+ }
+
+ state->num_locks = i * 32;
+ state->io_base = io_base;
+
+ platform_set_drvdata(pdev, state);
+
+ /*
+ * runtime PM will make sure the clock of this module is
+ * enabled iff at least one lock is requested
+ */
+ pm_runtime_enable(&pdev->dev);
+
+ for (i = 0; i < state->num_locks; i++) {
+ omap_lock = kzalloc(sizeof(*omap_lock), GFP_KERNEL);
+ if (!omap_lock) {
+ ret = -ENOMEM;
+ goto free_locks;
+ }
+
+ omap_lock->lock.dev = &pdev->dev;
+ omap_lock->lock.owner = THIS_MODULE;
+ omap_lock->lock.id = i;
+ omap_lock->lock.ops = &omap_hwspinlock_ops;
+ omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
+
+ ret = hwspin_lock_register(&omap_lock->lock);
+ if (ret) {
+ kfree(omap_lock);
+ goto free_locks;
+ }
+ }
+
+ return 0;
+
+free_locks:
+ while (--i >= 0) {
+ lock = hwspin_lock_unregister(i);
+ /* this should't happen, but let's give our best effort */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
+ continue;
+ }
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+ pm_runtime_disable(&pdev->dev);
+iounmap_base:
+ iounmap(io_base);
+free_state:
+ kfree(state);
+ return ret;
+}
+
+static int omap_hwspinlock_remove(struct platform_device *pdev)
+{
+ struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
+ struct hwspinlock *lock;
+ struct omap_hwspinlock *omap_lock;
+ int i;
+
+ for (i = 0; i < state->num_locks; i++) {
+ lock = hwspin_lock_unregister(i);
+ /* this shouldn't happen at this point. if it does, at least
+ * don't continue with the remove */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
+ return -EBUSY;
+ }
+
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+
+ pm_runtime_disable(&pdev->dev);
+ iounmap(state->io_base);
+ kfree(state);
+
+ return 0;
+}
+
+static struct platform_driver omap_hwspinlock_driver = {
+ .probe = omap_hwspinlock_probe,
+ .remove = omap_hwspinlock_remove,
+ .driver = {
+ .name = "omap_hwspinlock",
+ },
+};
+
+static int __init omap_hwspinlock_init(void)
+{
+ return platform_driver_register(&omap_hwspinlock_driver);
+}
+/* board init code might need to reserve hwspinlocks for predefined purposes */
+postcore_initcall(omap_hwspinlock_init);
+
+static void __exit omap_hwspinlock_exit(void)
+{
+ platform_driver_unregister(&omap_hwspinlock_driver);
+}
+module_exit(omap_hwspinlock_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
+MODULE_AUTHOR("Simon Que <sque@ti.com>");
+MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 3/4] OMAP4: hwmod data: Add hwspinlock
2010-12-03 23:50 ` Ohad Ben-Cohen
(?)
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann,
Paul Walmsley
From: Benoit Cousson <b-cousson@ti.com>
Add hwspinlock hwmod data for OMAP4 chip
Signed-off-by: Cousson, Benoit <b-cousson@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++++++++++++++++++++++++++
1 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
index d258936..e577d54 100644
--- a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
+++ b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
@@ -1376,6 +1376,67 @@ static struct omap_hwmod omap44xx_gpio6_hwmod = {
.slaves_cnt = ARRAY_SIZE(omap44xx_gpio6_slaves),
.omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP4430),
};
+
+/*
+ * 'spinlock' class
+ * spinlock provides hardware assistance for synchronizing the processes
+ * running on multiple processors
+ */
+
+static struct omap_hwmod_class_sysconfig omap44xx_spinlock_sysc = {
+ .rev_offs = 0x0000,
+ .sysc_offs = 0x0010,
+ .syss_offs = 0x0014,
+ .sysc_flags = (SYSC_HAS_AUTOIDLE | SYSC_HAS_CLOCKACTIVITY |
+ SYSC_HAS_ENAWAKEUP | SYSC_HAS_SIDLEMODE |
+ SYSC_HAS_SOFTRESET | SYSS_HAS_RESET_STATUS),
+ .idlemodes = (SIDLE_FORCE | SIDLE_NO | SIDLE_SMART),
+ .sysc_fields = &omap_hwmod_sysc_type1,
+};
+
+static struct omap_hwmod_class omap44xx_spinlock_hwmod_class = {
+ .name = "spinlock",
+ .sysc = &omap44xx_spinlock_sysc,
+};
+
+/* spinlock */
+static struct omap_hwmod omap44xx_spinlock_hwmod;
+static struct omap_hwmod_addr_space omap44xx_spinlock_addrs[] = {
+ {
+ .pa_start = 0x4a0f6000,
+ .pa_end = 0x4a0f6fff,
+ .flags = ADDR_TYPE_RT
+ },
+};
+
+/* l4_cfg -> spinlock */
+static struct omap_hwmod_ocp_if omap44xx_l4_cfg__spinlock = {
+ .master = &omap44xx_l4_cfg_hwmod,
+ .slave = &omap44xx_spinlock_hwmod,
+ .clk = "l4_div_ck",
+ .addr = omap44xx_spinlock_addrs,
+ .addr_cnt = ARRAY_SIZE(omap44xx_spinlock_addrs),
+ .user = OCP_USER_MPU | OCP_USER_SDMA,
+};
+
+/* spinlock slave ports */
+static struct omap_hwmod_ocp_if *omap44xx_spinlock_slaves[] = {
+ &omap44xx_l4_cfg__spinlock,
+};
+
+static struct omap_hwmod omap44xx_spinlock_hwmod = {
+ .name = "spinlock",
+ .class = &omap44xx_spinlock_hwmod_class,
+ .prcm = {
+ .omap4 = {
+ .clkctrl_reg = OMAP4430_CM_L4CFG_HW_SEM_CLKCTRL,
+ },
+ },
+ .slaves = omap44xx_spinlock_slaves,
+ .slaves_cnt = ARRAY_SIZE(omap44xx_spinlock_slaves),
+ .omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP4430),
+};
+
static __initdata struct omap_hwmod *omap44xx_hwmods[] = {
/* dmm class */
&omap44xx_dmm_hwmod,
@@ -1418,6 +1479,9 @@ static __initdata struct omap_hwmod *omap44xx_hwmods[] = {
&omap44xx_uart2_hwmod,
&omap44xx_uart3_hwmod,
&omap44xx_uart4_hwmod,
+
+ /* spinlock class */
+ &omap44xx_spinlock_hwmod,
NULL,
};
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 3/4] OMAP4: hwmod data: Add hwspinlock
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann,
Paul Walmsley
From: Benoit Cousson <b-cousson@ti.com>
Add hwspinlock hwmod data for OMAP4 chip
Signed-off-by: Cousson, Benoit <b-cousson@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++++++++++++++++++++++++++
1 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
index d258936..e577d54 100644
--- a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
+++ b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
@@ -1376,6 +1376,67 @@ static struct omap_hwmod omap44xx_gpio6_hwmod = {
.slaves_cnt = ARRAY_SIZE(omap44xx_gpio6_slaves),
.omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP4430),
};
+
+/*
+ * 'spinlock' class
+ * spinlock provides hardware assistance for synchronizing the processes
+ * running on multiple processors
+ */
+
+static struct omap_hwmod_class_sysconfig omap44xx_spinlock_sysc = {
+ .rev_offs = 0x0000,
+ .sysc_offs = 0x0010,
+ .syss_offs = 0x0014,
+ .sysc_flags = (SYSC_HAS_AUTOIDLE | SYSC_HAS_CLOCKACTIVITY |
+ SYSC_HAS_ENAWAKEUP | SYSC_HAS_SIDLEMODE |
+ SYSC_HAS_SOFTRESET | SYSS_HAS_RESET_STATUS),
+ .idlemodes = (SIDLE_FORCE | SIDLE_NO | SIDLE_SMART),
+ .sysc_fields = &omap_hwmod_sysc_type1,
+};
+
+static struct omap_hwmod_class omap44xx_spinlock_hwmod_class = {
+ .name = "spinlock",
+ .sysc = &omap44xx_spinlock_sysc,
+};
+
+/* spinlock */
+static struct omap_hwmod omap44xx_spinlock_hwmod;
+static struct omap_hwmod_addr_space omap44xx_spinlock_addrs[] = {
+ {
+ .pa_start = 0x4a0f6000,
+ .pa_end = 0x4a0f6fff,
+ .flags = ADDR_TYPE_RT
+ },
+};
+
+/* l4_cfg -> spinlock */
+static struct omap_hwmod_ocp_if omap44xx_l4_cfg__spinlock = {
+ .master = &omap44xx_l4_cfg_hwmod,
+ .slave = &omap44xx_spinlock_hwmod,
+ .clk = "l4_div_ck",
+ .addr = omap44xx_spinlock_addrs,
+ .addr_cnt = ARRAY_SIZE(omap44xx_spinlock_addrs),
+ .user = OCP_USER_MPU | OCP_USER_SDMA,
+};
+
+/* spinlock slave ports */
+static struct omap_hwmod_ocp_if *omap44xx_spinlock_slaves[] = {
+ &omap44xx_l4_cfg__spinlock,
+};
+
+static struct omap_hwmod omap44xx_spinlock_hwmod = {
+ .name = "spinlock",
+ .class = &omap44xx_spinlock_hwmod_class,
+ .prcm = {
+ .omap4 = {
+ .clkctrl_reg = OMAP4430_CM_L4CFG_HW_SEM_CLKCTRL,
+ },
+ },
+ .slaves = omap44xx_spinlock_slaves,
+ .slaves_cnt = ARRAY_SIZE(omap44xx_spinlock_slaves),
+ .omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP4430),
+};
+
static __initdata struct omap_hwmod *omap44xx_hwmods[] = {
/* dmm class */
&omap44xx_dmm_hwmod,
@@ -1418,6 +1479,9 @@ static __initdata struct omap_hwmod *omap44xx_hwmods[] = {
&omap44xx_uart2_hwmod,
&omap44xx_uart3_hwmod,
&omap44xx_uart4_hwmod,
+
+ /* spinlock class */
+ &omap44xx_spinlock_hwmod,
NULL,
};
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 3/4] OMAP4: hwmod data: Add hwspinlock
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-arm-kernel
From: Benoit Cousson <b-cousson@ti.com>
Add hwspinlock hwmod data for OMAP4 chip
Signed-off-by: Cousson, Benoit <b-cousson@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++++++++++++++++++++++++++
1 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
index d258936..e577d54 100644
--- a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
+++ b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
@@ -1376,6 +1376,67 @@ static struct omap_hwmod omap44xx_gpio6_hwmod = {
.slaves_cnt = ARRAY_SIZE(omap44xx_gpio6_slaves),
.omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP4430),
};
+
+/*
+ * 'spinlock' class
+ * spinlock provides hardware assistance for synchronizing the processes
+ * running on multiple processors
+ */
+
+static struct omap_hwmod_class_sysconfig omap44xx_spinlock_sysc = {
+ .rev_offs = 0x0000,
+ .sysc_offs = 0x0010,
+ .syss_offs = 0x0014,
+ .sysc_flags = (SYSC_HAS_AUTOIDLE | SYSC_HAS_CLOCKACTIVITY |
+ SYSC_HAS_ENAWAKEUP | SYSC_HAS_SIDLEMODE |
+ SYSC_HAS_SOFTRESET | SYSS_HAS_RESET_STATUS),
+ .idlemodes = (SIDLE_FORCE | SIDLE_NO | SIDLE_SMART),
+ .sysc_fields = &omap_hwmod_sysc_type1,
+};
+
+static struct omap_hwmod_class omap44xx_spinlock_hwmod_class = {
+ .name = "spinlock",
+ .sysc = &omap44xx_spinlock_sysc,
+};
+
+/* spinlock */
+static struct omap_hwmod omap44xx_spinlock_hwmod;
+static struct omap_hwmod_addr_space omap44xx_spinlock_addrs[] = {
+ {
+ .pa_start = 0x4a0f6000,
+ .pa_end = 0x4a0f6fff,
+ .flags = ADDR_TYPE_RT
+ },
+};
+
+/* l4_cfg -> spinlock */
+static struct omap_hwmod_ocp_if omap44xx_l4_cfg__spinlock = {
+ .master = &omap44xx_l4_cfg_hwmod,
+ .slave = &omap44xx_spinlock_hwmod,
+ .clk = "l4_div_ck",
+ .addr = omap44xx_spinlock_addrs,
+ .addr_cnt = ARRAY_SIZE(omap44xx_spinlock_addrs),
+ .user = OCP_USER_MPU | OCP_USER_SDMA,
+};
+
+/* spinlock slave ports */
+static struct omap_hwmod_ocp_if *omap44xx_spinlock_slaves[] = {
+ &omap44xx_l4_cfg__spinlock,
+};
+
+static struct omap_hwmod omap44xx_spinlock_hwmod = {
+ .name = "spinlock",
+ .class = &omap44xx_spinlock_hwmod_class,
+ .prcm = {
+ .omap4 = {
+ .clkctrl_reg = OMAP4430_CM_L4CFG_HW_SEM_CLKCTRL,
+ },
+ },
+ .slaves = omap44xx_spinlock_slaves,
+ .slaves_cnt = ARRAY_SIZE(omap44xx_spinlock_slaves),
+ .omap_chip = OMAP_CHIP_INIT(CHIP_IS_OMAP4430),
+};
+
static __initdata struct omap_hwmod *omap44xx_hwmods[] = {
/* dmm class */
&omap44xx_dmm_hwmod,
@@ -1418,6 +1479,9 @@ static __initdata struct omap_hwmod *omap44xx_hwmods[] = {
&omap44xx_uart2_hwmod,
&omap44xx_uart3_hwmod,
&omap44xx_uart4_hwmod,
+
+ /* spinlock class */
+ &omap44xx_spinlock_hwmod,
NULL,
};
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 4/4] omap: add hwspinlock device
2010-12-03 23:50 ` Ohad Ben-Cohen
(?)
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann,
Simon Que, Paul Walmsley
From: Simon Que <sque@ti.com>
Build and register an hwspinlock platform device.
Although only OMAP4 supports the hardware spinlock module (for now),
it is still safe to run this initcall on all omaps, because hwmod lookup
will simply fail on hwspinlock-less platforms.
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap2/Makefile | 1 +
arch/arm/mach-omap2/hwspinlock.c | 63 ++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-omap2/hwspinlock.c
diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index fbc8739..0ea2df3 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -197,3 +197,4 @@ obj-y += $(smc91x-m) $(smc91x-y)
smsc911x-$(CONFIG_SMSC911X) := gpmc-smsc911x.o
obj-y += $(smsc911x-m) $(smsc911x-y)
+obj-$(CONFIG_ARCH_OMAP4) += hwspinlock.o
diff --git a/arch/arm/mach-omap2/hwspinlock.c b/arch/arm/mach-omap2/hwspinlock.c
new file mode 100644
index 0000000..06d4a80
--- /dev/null
+++ b/arch/arm/mach-omap2/hwspinlock.c
@@ -0,0 +1,63 @@
+/*
+ * OMAP hardware spinlock device initialization
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/err.h>
+
+#include <plat/omap_hwmod.h>
+#include <plat/omap_device.h>
+
+struct omap_device_pm_latency omap_spinlock_latency[] = {
+ {
+ .deactivate_func = omap_device_idle_hwmods,
+ .activate_func = omap_device_enable_hwmods,
+ .flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST,
+ }
+};
+
+int __init hwspinlocks_init(void)
+{
+ int retval = 0;
+ struct omap_hwmod *oh;
+ struct omap_device *od;
+ const char *oh_name = "spinlock";
+ const char *dev_name = "omap_hwspinlock";
+
+ /*
+ * Hwmod lookup will fail in case our platform doesn't support the
+ * hardware spinlock module, so it is safe to run this initcall
+ * on all omaps
+ */
+ oh = omap_hwmod_lookup(oh_name);
+ if (oh == NULL)
+ return -EINVAL;
+
+ od = omap_device_build(dev_name, 0, oh, NULL, 0,
+ omap_spinlock_latency,
+ ARRAY_SIZE(omap_spinlock_latency), false);
+ if (IS_ERR(od)) {
+ pr_err("Can't build omap_device for %s:%s\n", dev_name,
+ oh_name);
+ retval = PTR_ERR(od);
+ }
+
+ return retval;
+}
+/* early board code might need to reserve specific hwspinlock instances */
+postcore_initcall(hwspinlocks_init);
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 4/4] omap: add hwspinlock device
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann,
Simon Que, Paul Walmsley
From: Simon Que <sque@ti.com>
Build and register an hwspinlock platform device.
Although only OMAP4 supports the hardware spinlock module (for now),
it is still safe to run this initcall on all omaps, because hwmod lookup
will simply fail on hwspinlock-less platforms.
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap2/Makefile | 1 +
arch/arm/mach-omap2/hwspinlock.c | 63 ++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-omap2/hwspinlock.c
diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index fbc8739..0ea2df3 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -197,3 +197,4 @@ obj-y += $(smc91x-m) $(smc91x-y)
smsc911x-$(CONFIG_SMSC911X) := gpmc-smsc911x.o
obj-y += $(smsc911x-m) $(smsc911x-y)
+obj-$(CONFIG_ARCH_OMAP4) += hwspinlock.o
diff --git a/arch/arm/mach-omap2/hwspinlock.c b/arch/arm/mach-omap2/hwspinlock.c
new file mode 100644
index 0000000..06d4a80
--- /dev/null
+++ b/arch/arm/mach-omap2/hwspinlock.c
@@ -0,0 +1,63 @@
+/*
+ * OMAP hardware spinlock device initialization
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/err.h>
+
+#include <plat/omap_hwmod.h>
+#include <plat/omap_device.h>
+
+struct omap_device_pm_latency omap_spinlock_latency[] = {
+ {
+ .deactivate_func = omap_device_idle_hwmods,
+ .activate_func = omap_device_enable_hwmods,
+ .flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST,
+ }
+};
+
+int __init hwspinlocks_init(void)
+{
+ int retval = 0;
+ struct omap_hwmod *oh;
+ struct omap_device *od;
+ const char *oh_name = "spinlock";
+ const char *dev_name = "omap_hwspinlock";
+
+ /*
+ * Hwmod lookup will fail in case our platform doesn't support the
+ * hardware spinlock module, so it is safe to run this initcall
+ * on all omaps
+ */
+ oh = omap_hwmod_lookup(oh_name);
+ if (oh == NULL)
+ return -EINVAL;
+
+ od = omap_device_build(dev_name, 0, oh, NULL, 0,
+ omap_spinlock_latency,
+ ARRAY_SIZE(omap_spinlock_latency), false);
+ if (IS_ERR(od)) {
+ pr_err("Can't build omap_device for %s:%s\n", dev_name,
+ oh_name);
+ retval = PTR_ERR(od);
+ }
+
+ return retval;
+}
+/* early board code might need to reserve specific hwspinlock instances */
+postcore_initcall(hwspinlocks_init);
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* [PATCH v3 4/4] omap: add hwspinlock device
@ 2010-12-03 23:50 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-03 23:50 UTC (permalink / raw)
To: linux-arm-kernel
From: Simon Que <sque@ti.com>
Build and register an hwspinlock platform device.
Although only OMAP4 supports the hardware spinlock module (for now),
it is still safe to run this initcall on all omaps, because hwmod lookup
will simply fail on hwspinlock-less platforms.
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap2/Makefile | 1 +
arch/arm/mach-omap2/hwspinlock.c | 63 ++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-omap2/hwspinlock.c
diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index fbc8739..0ea2df3 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -197,3 +197,4 @@ obj-y += $(smc91x-m) $(smc91x-y)
smsc911x-$(CONFIG_SMSC911X) := gpmc-smsc911x.o
obj-y += $(smsc911x-m) $(smsc911x-y)
+obj-$(CONFIG_ARCH_OMAP4) += hwspinlock.o
diff --git a/arch/arm/mach-omap2/hwspinlock.c b/arch/arm/mach-omap2/hwspinlock.c
new file mode 100644
index 0000000..06d4a80
--- /dev/null
+++ b/arch/arm/mach-omap2/hwspinlock.c
@@ -0,0 +1,63 @@
+/*
+ * OMAP hardware spinlock device initialization
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/err.h>
+
+#include <plat/omap_hwmod.h>
+#include <plat/omap_device.h>
+
+struct omap_device_pm_latency omap_spinlock_latency[] = {
+ {
+ .deactivate_func = omap_device_idle_hwmods,
+ .activate_func = omap_device_enable_hwmods,
+ .flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST,
+ }
+};
+
+int __init hwspinlocks_init(void)
+{
+ int retval = 0;
+ struct omap_hwmod *oh;
+ struct omap_device *od;
+ const char *oh_name = "spinlock";
+ const char *dev_name = "omap_hwspinlock";
+
+ /*
+ * Hwmod lookup will fail in case our platform doesn't support the
+ * hardware spinlock module, so it is safe to run this initcall
+ * on all omaps
+ */
+ oh = omap_hwmod_lookup(oh_name);
+ if (oh == NULL)
+ return -EINVAL;
+
+ od = omap_device_build(dev_name, 0, oh, NULL, 0,
+ omap_spinlock_latency,
+ ARRAY_SIZE(omap_spinlock_latency), false);
+ if (IS_ERR(od)) {
+ pr_err("Can't build omap_device for %s:%s\n", dev_name,
+ oh_name);
+ retval = PTR_ERR(od);
+ }
+
+ return retval;
+}
+/* early board code might need to reserve specific hwspinlock instances */
+postcore_initcall(hwspinlocks_init);
--
1.7.0.4
^ permalink raw reply related [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-03 23:50 ` Ohad Ben-Cohen
` (5 preceding siblings ...)
(?)
@ 2010-12-04 0:29 ` David Daney
2010-12-04 1:28 ` Ohad Ben-Cohen
-1 siblings, 1 reply; 40+ messages in thread
From: David Daney @ 2010-12-04 0:29 UTC (permalink / raw)
To: Ohad Ben-Cohen
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Greg KH,
Tony Lindgren, Benoit Cousson, Grant Likely, Hari Kanigeri,
Suman Anna, Kevin Hilman, Arnd Bergmann
On 12/03/2010 03:50 PM, Ohad Ben-Cohen wrote:
> OMAP4 introduces a Hardware Spinlock device, which provides hardware
> assistance for synchronization and mutual exclusion between heterogeneous
> processors and those not operating under a single, shared operating system
> (e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
>
> The intention of this hardware device is to allow remote processors,
> that have no alternative mechanism to accomplish synchronization and mutual
> exclusion operations, to share resources (such as memory and/or any other
> hardware resource).
>
Does anything other than OMAP4 have one of these things? And are there
any devices that are commonly encountered across more than one platform
that might have these hardware spinlocks, thus making it advantageous to
have a common framework?
If not why a general purpose framework for a very chip specific feature?
There are chips with hardware atomic memory, but the only time it makes
sense to use it is in conjunction with specialize on-chip devices. So
the implementation details are kept in the drivers rather than creating
a general purpose hwatomic (with its hwatomic_add() et al.) type.
David Daney
> This patchset adds hwspinlock framework that makes it possible
> for drivers to use those hwspinlock devices and stay platform-independent.
>
> Currently there are two users for this hwspinlock interface:
>
> 1. Inter-processor communications: on OMAP4, cpu-intensive multimedia
> tasks are offloaded by the host to the remote M3 and/or C64x+ slave
> processors.
>
> To achieve fast message-based communications, a minimal kernel support
> is needed to deliver messages arriving from a remote processor to the
> appropriate user process.
>
> This communication is based on a simple data structure that is shared between
> the remote processors, and access to it is synchronized using the hwspinlock
> module (remote processor directly places new messages in this shared data
> structure).
>
> 2. On some OMAP4 boards, the I2C bus is shared between the A9 and the M3,
> and the hwspinlock is used to synchronize access to it.
>
> While (2) can get away with an omap-specific hwspinlock implementation,
> (1) is by no means omap-specific, and a common hwspinlock interface is
> needed to keep it generic, in hopes that it will be useful for other
> platforms as well.
>
> Changes v2->v3:
> - Remove the timeout-less _lock API variant (Tony)
> - s/state->io_base/io_base/ (Ionut)
> - Remove the "generic" wording (David)
> - s/hwspinlock_/hwspin_lock_/ (Mugdha)
> - Use MAX_SCHEDULE_TIMEOUT to indicate no timeout (Mugdha)
> - Be more verbose on egregious API misuse (Olof)
> - locking API misuse is BUG_ON material (Russell)
>
> Note: Russell also suggested compiling out NULL checks on ARM.
> I've posted an initial proposal for this (see
> https://lkml.org/lkml/2010/11/29/96), which I'm going to resubmit
> separately. If accepted, I'll adopt hwspinlocks to use it.
>
> Patches are tested against linux-omap-2.6 master, which is 2.6.37-rc4 plus
> omap material. All, but the third (the hwmod omap patch), apply on top of
> mainline 2.6.37-rc4 as well
>
> Changes v1->v2:
> - Convert to a generic interface (Tony)
> - API should silently succeed if framework isn't built (Greg)
> - Don't use ERR_PTR pattern (Grant)
> - Use tristate, fix and extend commentary (Kevin)
> - Provide API flexibility regarding irq handling (Arnd, Grant)
>
> Note: after reviewing OMAP's L4 access times, and comparing them with
> external memory latencies, I can say that there is no notable difference.
> Because of that, we can safely treat the hwspinlock like we do
> with regular spinlocks: preemption should be disabled, but whether
> to disable interrupts or not is up to the caller.
>
> So despite the TRM's recommendation to always disable local interrupts
> when taking an OMAP Hardware Spinlock, I have decided to allow callers
> not to do that (by providing the full extent of hwspin_lock(),
> hwspin_lock_irq() and hwspin_lock_irqsave() API).
>
> Just like regular spinlocks, it's up to the callers to decide whether
> interrupts should be disabled or not.
>
> Sleeping, btw, is still prohibited of course.
>
> Contributions:
>
> Previous versions of an omap-specific hwspinlock driver circulated in
> linux-omap several times, and received substantial attention and contribution
> from many developers (see [1][2][3][4][5][6]):
>
> Simon Que did the initial implementation and pushed several iterations
> Benoit Cousson provided extensive review, help, improvements and hwmod support
> Hari Kanigeri helped out when Simon was away
> Sanjeev Premi, Santosh Shilimkar and Nishanth Menon did lots of review
>
> I'd like to thank Benoit Cousson, Steve Krueger, Hari Kanigeri,
> Nourredine Hamoudi and Richard Woodruff for useful discussions about
> the OMAP Spinlock requirements and use-cases.
>
> Relevant linux-omap threads:
>
> [1] http://thread.gmane.org/gmane.linux.ports.arm.omap/38755
> [2] http://thread.gmane.org/gmane.linux.ports.arm.omap/38917
> [3] http://thread.gmane.org/gmane.linux.ports.arm.omap/39187
> [4] http://thread.gmane.org/gmane.linux.ports.arm.omap/39365
> [5] http://thread.gmane.org/gmane.linux.ports.arm.omap/39815
> [6] http://thread.gmane.org/gmane.linux.ports.arm.omap/40901
>
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-04 0:29 ` [PATCH v3 0/4] Introduce hardware spinlock framework David Daney
2010-12-04 1:28 ` Ohad Ben-Cohen
@ 2010-12-04 1:28 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-04 1:28 UTC (permalink / raw)
To: David Daney
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Greg KH,
Tony Lindgren, Benoit Cousson, Grant Likely, Hari Kanigeri,
Suman Anna, Kevin Hilman, Arnd Bergmann
On Sat, Dec 4, 2010 at 2:29 AM, David Daney <ddaney@caviumnetworks.com> wrote:
> Does anything other than OMAP4 have one of these things?
I'm not aware of any, but David Brownell had some ideas about it in
our previous v2 discussion (see
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg39413.html).
Btw, you might want to read throughout that entire discussion with
David, since it was touching the same questions you raise here.
> And are there any
> devices that are commonly encountered across more than one platform that
> might have these hardware spinlocks, thus making it advantageous to have a
> common framework?
Such devices are just multiple processors that have no alternative
mechanism to accomplish synchronization.
OMAP4 has a few non-coherent heterogeneous processors that do not
support fancy synchronization primitives, so it needs this hwspinlock
peripheral.
Otherwise, I don't know how common that is (/might become), and I'd
hate speculating, but I suspect that OMAP is not going to be the only
platform with multiple coprocessors, that have no other means of
achieving synchronization, and with which inter-processor
communications is desired.
>
> If not why a general purpose framework for a very chip specific feature?
We started out with an omap-specific driver (see first iteration at
http://lwn.net/Articles/410375/), but were asked to make it a
platform-agnostic framework, in order to keep the IPC drivers that
will use it generic (and assuming that more users will show up for
such framework).
To me it sounds reasonable, but again, I prefer not to speculate how
many users will show up for this, if any.
Both ways (framework / omap-specific driver) will work for us just fine.
>
> There are chips with hardware atomic memory, but the only time it makes
> sense to use it is in conjunction with specialize on-chip devices. So the
> implementation details are kept in the drivers rather than creating a
> general purpose hwatomic (with its hwatomic_add() et al.) type.
This case is a bit different IMHO: some of the potential users of
hwspinlocks are just generic IPC drivers that are by no means
platform-specific. It's not a special on-chip device: it's just one
processor, trying to achieve mutual exclusion with another processor,
before manipulating some shared data structure.
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-04 1:28 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-04 1:28 UTC (permalink / raw)
To: David Daney
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Greg KH,
Tony Lindgren, Benoit Cousson, Grant Likely, Hari Kanigeri,
Suman Anna, Kevin Hilman, Arnd Bergmann
On Sat, Dec 4, 2010 at 2:29 AM, David Daney <ddaney@caviumnetworks.com> wrote:
> Does anything other than OMAP4 have one of these things?
I'm not aware of any, but David Brownell had some ideas about it in
our previous v2 discussion (see
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg39413.html).
Btw, you might want to read throughout that entire discussion with
David, since it was touching the same questions you raise here.
> And are there any
> devices that are commonly encountered across more than one platform that
> might have these hardware spinlocks, thus making it advantageous to have a
> common framework?
Such devices are just multiple processors that have no alternative
mechanism to accomplish synchronization.
OMAP4 has a few non-coherent heterogeneous processors that do not
support fancy synchronization primitives, so it needs this hwspinlock
peripheral.
Otherwise, I don't know how common that is (/might become), and I'd
hate speculating, but I suspect that OMAP is not going to be the only
platform with multiple coprocessors, that have no other means of
achieving synchronization, and with which inter-processor
communications is desired.
>
> If not why a general purpose framework for a very chip specific feature?
We started out with an omap-specific driver (see first iteration at
http://lwn.net/Articles/410375/), but were asked to make it a
platform-agnostic framework, in order to keep the IPC drivers that
will use it generic (and assuming that more users will show up for
such framework).
To me it sounds reasonable, but again, I prefer not to speculate how
many users will show up for this, if any.
Both ways (framework / omap-specific driver) will work for us just fine.
>
> There are chips with hardware atomic memory, but the only time it makes
> sense to use it is in conjunction with specialize on-chip devices. So the
> implementation details are kept in the drivers rather than creating a
> general purpose hwatomic (with its hwatomic_add() et al.) type.
This case is a bit different IMHO: some of the potential users of
hwspinlocks are just generic IPC drivers that are by no means
platform-specific. It's not a special on-chip device: it's just one
processor, trying to achieve mutual exclusion with another processor,
before manipulating some shared data structure.
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-04 1:28 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-04 1:28 UTC (permalink / raw)
To: linux-arm-kernel
On Sat, Dec 4, 2010 at 2:29 AM, David Daney <ddaney@caviumnetworks.com> wrote:
> Does anything other than OMAP4 have one of these things?
I'm not aware of any, but David Brownell had some ideas about it in
our previous v2 discussion (see
http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39413.html).
Btw, you might want to read throughout that entire discussion with
David, since it was touching the same questions you raise here.
> And are there any
> devices that are commonly encountered across more than one platform that
> might have these hardware spinlocks, thus making it advantageous to have a
> common framework?
Such devices are just multiple processors that have no alternative
mechanism to accomplish synchronization.
OMAP4 has a few non-coherent heterogeneous processors that do not
support fancy synchronization primitives, so it needs this hwspinlock
peripheral.
Otherwise, I don't know how common that is (/might become), and I'd
hate speculating, but I suspect that OMAP is not going to be the only
platform with multiple coprocessors, that have no other means of
achieving synchronization, and with which inter-processor
communications is desired.
>
> If not why a general purpose framework for a very chip specific feature?
We started out with an omap-specific driver (see first iteration at
http://lwn.net/Articles/410375/), but were asked to make it a
platform-agnostic framework, in order to keep the IPC drivers that
will use it generic (and assuming that more users will show up for
such framework).
To me it sounds reasonable, but again, I prefer not to speculate how
many users will show up for this, if any.
Both ways (framework / omap-specific driver) will work for us just fine.
>
> There are chips with hardware atomic memory, but the only time it makes
> sense to use it is in conjunction with specialize on-chip devices. ?So the
> implementation details are kept in the drivers rather than creating a
> general purpose hwatomic (with its hwatomic_add() et al.) type.
This case is a bit different IMHO: some of the potential users of
hwspinlocks are just generic IPC drivers that are by no means
platform-specific. It's not a special on-chip device: it's just one
processor, trying to achieve mutual exclusion with another processor,
before manipulating some shared data structure.
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-03 23:50 ` Ohad Ben-Cohen
@ 2010-12-14 14:31 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-14 14:31 UTC (permalink / raw)
To: linux-omap, linux-kernel, linux-arm-kernel
Cc: akpm, Greg KH, Tony Lindgren, Benoit Cousson, Grant Likely,
Hari Kanigeri, Suman Anna, Kevin Hilman, Arnd Bergmann
Hi Greg, Tony,
On Sat, Dec 4, 2010 at 1:50 AM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> OMAP4 introduces a Hardware Spinlock device, which provides hardware
> assistance for synchronization and mutual exclusion between heterogeneous
> processors and those not operating under a single, shared operating system
> (e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
>
> The intention of this hardware device is to allow remote processors,
> that have no alternative mechanism to accomplish synchronization and mutual
> exclusion operations, to share resources (such as memory and/or any other
> hardware resource).
>
> This patchset adds hwspinlock framework that makes it possible
> for drivers to use those hwspinlock devices and stay platform-independent.
...
> Documentation/hwspinlock.txt | 299 +++++++++++++++
> arch/arm/mach-omap2/Makefile | 1 +
> arch/arm/mach-omap2/hwspinlock.c | 63 ++++
> arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++
> drivers/Kconfig | 2 +
> drivers/Makefile | 1 +
> drivers/hwspinlock/Kconfig | 22 ++
> drivers/hwspinlock/Makefile | 6 +
> drivers/hwspinlock/hwspinlock.h | 61 +++
> drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++
> drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++
> include/linux/hwspinlock.h | 298 +++++++++++++++
> 12 files changed, 1605 insertions(+), 0 deletions(-)
Can you please have a look and say if this looks OK ?
If it does, where would you prefer this to go through ?
Thanks,
Ohad.
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-14 14:31 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-14 14:31 UTC (permalink / raw)
To: linux-arm-kernel
Hi Greg, Tony,
On Sat, Dec 4, 2010 at 1:50 AM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> OMAP4 introduces a Hardware Spinlock device, which provides hardware
> assistance for synchronization and mutual exclusion between heterogeneous
> processors and those not operating under a single, shared operating system
> (e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
>
> The intention of this hardware device is to allow remote processors,
> that have no alternative mechanism to accomplish synchronization and mutual
> exclusion operations, to share resources (such as memory and/or any other
> hardware resource).
>
> This patchset adds hwspinlock framework that makes it possible
> for drivers to use those hwspinlock devices and stay platform-independent.
...
> ?Documentation/hwspinlock.txt ? ? ? ? ? ? ? | ?299 +++++++++++++++
> ?arch/arm/mach-omap2/Makefile ? ? ? ? ? ? ? | ? ?1 +
> ?arch/arm/mach-omap2/hwspinlock.c ? ? ? ? ? | ? 63 ++++
> ?arch/arm/mach-omap2/omap_hwmod_44xx_data.c | ? 64 ++++
> ?drivers/Kconfig ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?2 +
> ?drivers/Makefile ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?1 +
> ?drivers/hwspinlock/Kconfig ? ? ? ? ? ? ? ? | ? 22 ++
> ?drivers/hwspinlock/Makefile ? ? ? ? ? ? ? ?| ? ?6 +
> ?drivers/hwspinlock/hwspinlock.h ? ? ? ? ? ?| ? 61 +++
> ?drivers/hwspinlock/hwspinlock_core.c ? ? ? | ?557 ++++++++++++++++++++++++++++
> ?drivers/hwspinlock/omap_hwspinlock.c ? ? ? | ?231 ++++++++++++
> ?include/linux/hwspinlock.h ? ? ? ? ? ? ? ? | ?298 +++++++++++++++
> ?12 files changed, 1605 insertions(+), 0 deletions(-)
Can you please have a look and say if this looks OK ?
If it does, where would you prefer this to go through ?
Thanks,
Ohad.
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-14 14:31 ` Ohad Ben-Cohen
@ 2010-12-14 17:06 ` Greg KH
-1 siblings, 0 replies; 40+ messages in thread
From: Greg KH @ 2010-12-14 17:06 UTC (permalink / raw)
To: Ohad Ben-Cohen
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Tony Lindgren,
Benoit Cousson, Grant Likely, Hari Kanigeri, Suman Anna,
Kevin Hilman, Arnd Bergmann
On Tue, Dec 14, 2010 at 04:31:36PM +0200, Ohad Ben-Cohen wrote:
> Hi Greg, Tony,
>
> On Sat, Dec 4, 2010 at 1:50 AM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> > OMAP4 introduces a Hardware Spinlock device, which provides hardware
> > assistance for synchronization and mutual exclusion between heterogeneous
> > processors and those not operating under a single, shared operating system
> > (e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
> >
> > The intention of this hardware device is to allow remote processors,
> > that have no alternative mechanism to accomplish synchronization and mutual
> > exclusion operations, to share resources (such as memory and/or any other
> > hardware resource).
> >
> > This patchset adds hwspinlock framework that makes it possible
> > for drivers to use those hwspinlock devices and stay platform-independent.
>
> ...
>
> > Documentation/hwspinlock.txt | 299 +++++++++++++++
> > arch/arm/mach-omap2/Makefile | 1 +
> > arch/arm/mach-omap2/hwspinlock.c | 63 ++++
> > arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 64 ++++
> > drivers/Kconfig | 2 +
> > drivers/Makefile | 1 +
> > drivers/hwspinlock/Kconfig | 22 ++
> > drivers/hwspinlock/Makefile | 6 +
> > drivers/hwspinlock/hwspinlock.h | 61 +++
> > drivers/hwspinlock/hwspinlock_core.c | 557 ++++++++++++++++++++++++++++
> > drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++
> > include/linux/hwspinlock.h | 298 +++++++++++++++
> > 12 files changed, 1605 insertions(+), 0 deletions(-)
>
> Can you please have a look and say if this looks OK ?
Look at what, I don't see a patch here.
I've seen a lot of discussion about this, are all of the review comments
now addressed? Like the most important one, why is this generic code if
it's only for one specific platform?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-14 17:06 ` Greg KH
0 siblings, 0 replies; 40+ messages in thread
From: Greg KH @ 2010-12-14 17:06 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Dec 14, 2010 at 04:31:36PM +0200, Ohad Ben-Cohen wrote:
> Hi Greg, Tony,
>
> On Sat, Dec 4, 2010 at 1:50 AM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> > OMAP4 introduces a Hardware Spinlock device, which provides hardware
> > assistance for synchronization and mutual exclusion between heterogeneous
> > processors and those not operating under a single, shared operating system
> > (e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
> >
> > The intention of this hardware device is to allow remote processors,
> > that have no alternative mechanism to accomplish synchronization and mutual
> > exclusion operations, to share resources (such as memory and/or any other
> > hardware resource).
> >
> > This patchset adds hwspinlock framework that makes it possible
> > for drivers to use those hwspinlock devices and stay platform-independent.
>
> ...
>
> > ?Documentation/hwspinlock.txt ? ? ? ? ? ? ? | ?299 +++++++++++++++
> > ?arch/arm/mach-omap2/Makefile ? ? ? ? ? ? ? | ? ?1 +
> > ?arch/arm/mach-omap2/hwspinlock.c ? ? ? ? ? | ? 63 ++++
> > ?arch/arm/mach-omap2/omap_hwmod_44xx_data.c | ? 64 ++++
> > ?drivers/Kconfig ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?2 +
> > ?drivers/Makefile ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?1 +
> > ?drivers/hwspinlock/Kconfig ? ? ? ? ? ? ? ? | ? 22 ++
> > ?drivers/hwspinlock/Makefile ? ? ? ? ? ? ? ?| ? ?6 +
> > ?drivers/hwspinlock/hwspinlock.h ? ? ? ? ? ?| ? 61 +++
> > ?drivers/hwspinlock/hwspinlock_core.c ? ? ? | ?557 ++++++++++++++++++++++++++++
> > ?drivers/hwspinlock/omap_hwspinlock.c ? ? ? | ?231 ++++++++++++
> > ?include/linux/hwspinlock.h ? ? ? ? ? ? ? ? | ?298 +++++++++++++++
> > ?12 files changed, 1605 insertions(+), 0 deletions(-)
>
> Can you please have a look and say if this looks OK ?
Look at what, I don't see a patch here.
I've seen a lot of discussion about this, are all of the review comments
now addressed? Like the most important one, why is this generic code if
it's only for one specific platform?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-14 17:06 ` Greg KH
@ 2010-12-14 18:40 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-14 18:40 UTC (permalink / raw)
To: Greg KH
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Tony Lindgren,
Benoit Cousson, Grant Likely, Hari Kanigeri, Suman Anna,
Kevin Hilman, Arnd Bergmann
On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
>> Can you please have a look and say if this looks OK ?
>
> Look at what, I don't see a patch here.
Here's the complete patchset:
http://www.mail-archive.com/linux-omap@vger.kernel.org/msg39833.html
If you prefer, I can resubmit.
>
> I've seen a lot of discussion about this, are all of the review comments
> now addressed?
Yes, all comments were addressed in this v3 iteration, and this thread
has been idle for about 10 days.
> Like the most important one, why is this generic code if
> it's only for one specific platform?
We started out with an omap-specific driver, but Tony preferred that we
make this a platform-agnostic framework, in order to keep the IPC drivers that
will use it generic, and assuming that more users will show up for
such framework.
To me it sounds reasonable, but both ways (framework / omap-specific
driver) will work for us just fine, and I can switch back to a misc
driver if this is preferred.
The complete discussion of v1 is at:
http://comments.gmane.org/gmane.linux.kernel/1049802
We also discussed this at v2 of the patches with David, see the
complete discussion at:
http://comments.gmane.org/gmane.linux.kernel/1067016
Thanks,
Ohad.
>
> thanks,
>
> greg k-h
>
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-14 18:40 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-14 18:40 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
>> Can you please have a look and say if this looks OK ?
>
> Look at what, I don't see a patch here.
Here's the complete patchset:
http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39833.html
If you prefer, I can resubmit.
>
> I've seen a lot of discussion about this, are all of the review comments
> now addressed?
Yes, all comments were addressed in this v3 iteration, and this thread
has been idle for about 10 days.
> ?Like the most important one, why is this generic code if
> it's only for one specific platform?
We started out with an omap-specific driver, but Tony preferred that we
make this a platform-agnostic framework, in order to keep the IPC drivers that
will use it generic, and assuming that more users will show up for
such framework.
To me it sounds reasonable, but both ways (framework / omap-specific
driver) will work for us just fine, and I can switch back to a misc
driver if this is preferred.
The complete discussion of v1 is at:
http://comments.gmane.org/gmane.linux.kernel/1049802
We also discussed this at v2 of the patches with David, see the
complete discussion at:
http://comments.gmane.org/gmane.linux.kernel/1067016
Thanks,
Ohad.
>
> thanks,
>
> greg k-h
>
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-14 18:40 ` Ohad Ben-Cohen
(?)
@ 2010-12-16 20:42 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-16 20:42 UTC (permalink / raw)
To: Greg KH
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Tony Lindgren,
Benoit Cousson, Grant Likely, Hari Kanigeri, Suman Anna,
Kevin Hilman, Arnd Bergmann
On Tue, Dec 14, 2010 at 8:40 PM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
>> Like the most important one, why is this generic code if
>> it's only for one specific platform?
>
> We started out with an omap-specific driver, but Tony preferred that we
> make this a platform-agnostic framework, in order to keep the IPC drivers that
> will use it generic, and assuming that more users will show up for
> such framework.
I was just told about additional users for this (thanks Mugdha):
1) There are several platforms (such as omap3530 and omapl1xx) that
have no such hardware support, but would still need to use the same
IPC drivers (to communicate with their DSP).
The only way to achieve mutual exclusion on those platforms is by
using a shared-memory synchronization algorithm called Peterson's
Algorithm [1]. We would still need the same hwspinlock framework for
that - the busy looping, the timeout, the various locking schemes, the
resource allocation - are all still valid. The only difference is the
actual lock implementation.
2) The C6474, which is a multi-core DSP device [2], have Linux running
on one of its cores, and would be using the same IPC drivers, too.
C6474 has hardware support for synchronization, which would also
benefit from such hwspinlock module (btw the C6474 has a richer
hardware module that would need more than the hwspinlock framework
offer today - it also supports queuing, owner semantics and interrupt
notification to let a processor know when it acquires a lock, so it
wouldn't have to spin..)
Thanks,
Ohad.
[1] http://en.wikipedia.org/wiki/Peterson's_algorithm
[2] http://focus.ti.com/docs/prod/folders/print/tms320c6474.html
> To me it sounds reasonable, but both ways (framework / omap-specific
> driver) will work for us just fine, and I can switch back to a misc
> driver if this is preferred.
>
> The complete discussion of v1 is at:
> http://comments.gmane.org/gmane.linux.kernel/1049802
>
> We also discussed this at v2 of the patches with David, see the
> complete discussion at:
> http://comments.gmane.org/gmane.linux.kernel/1067016
>
> Thanks,
> Ohad.
>
>>
>> thanks,
>>
>> greg k-h
>>
>
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-16 20:42 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-16 20:42 UTC (permalink / raw)
To: Greg KH
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Tony Lindgren,
Benoit Cousson, Grant Likely, Hari Kanigeri, Suman Anna,
Kevin Hilman, Arnd Bergmann
On Tue, Dec 14, 2010 at 8:40 PM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
>> Like the most important one, why is this generic code if
>> it's only for one specific platform?
>
> We started out with an omap-specific driver, but Tony preferred that we
> make this a platform-agnostic framework, in order to keep the IPC drivers that
> will use it generic, and assuming that more users will show up for
> such framework.
I was just told about additional users for this (thanks Mugdha):
1) There are several platforms (such as omap3530 and omapl1xx) that
have no such hardware support, but would still need to use the same
IPC drivers (to communicate with their DSP).
The only way to achieve mutual exclusion on those platforms is by
using a shared-memory synchronization algorithm called Peterson's
Algorithm [1]. We would still need the same hwspinlock framework for
that - the busy looping, the timeout, the various locking schemes, the
resource allocation - are all still valid. The only difference is the
actual lock implementation.
2) The C6474, which is a multi-core DSP device [2], have Linux running
on one of its cores, and would be using the same IPC drivers, too.
C6474 has hardware support for synchronization, which would also
benefit from such hwspinlock module (btw the C6474 has a richer
hardware module that would need more than the hwspinlock framework
offer today - it also supports queuing, owner semantics and interrupt
notification to let a processor know when it acquires a lock, so it
wouldn't have to spin..)
Thanks,
Ohad.
[1] http://en.wikipedia.org/wiki/Peterson's_algorithm
[2] http://focus.ti.com/docs/prod/folders/print/tms320c6474.html
> To me it sounds reasonable, but both ways (framework / omap-specific
> driver) will work for us just fine, and I can switch back to a misc
> driver if this is preferred.
>
> The complete discussion of v1 is at:
> http://comments.gmane.org/gmane.linux.kernel/1049802
>
> We also discussed this at v2 of the patches with David, see the
> complete discussion at:
> http://comments.gmane.org/gmane.linux.kernel/1067016
>
> Thanks,
> Ohad.
>
>>
>> thanks,
>>
>> greg k-h
>>
>
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^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-16 20:42 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-16 20:42 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Dec 14, 2010 at 8:40 PM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
>> ?Like the most important one, why is this generic code if
>> ?it's only for one specific platform?
>
> We started out with an omap-specific driver, but Tony preferred that we
> make this a platform-agnostic framework, in order to keep the IPC drivers that
> will use it generic, and assuming that more users will show up for
> such framework.
I was just told about additional users for this (thanks Mugdha):
1) There are several platforms (such as omap3530 and omapl1xx) that
have no such hardware support, but would still need to use the same
IPC drivers (to communicate with their DSP).
The only way to achieve mutual exclusion on those platforms is by
using a shared-memory synchronization algorithm called Peterson's
Algorithm [1]. We would still need the same hwspinlock framework for
that - the busy looping, the timeout, the various locking schemes, the
resource allocation - are all still valid. The only difference is the
actual lock implementation.
2) The C6474, which is a multi-core DSP device [2], have Linux running
on one of its cores, and would be using the same IPC drivers, too.
C6474 has hardware support for synchronization, which would also
benefit from such hwspinlock module (btw the C6474 has a richer
hardware module that would need more than the hwspinlock framework
offer today - it also supports queuing, owner semantics and interrupt
notification to let a processor know when it acquires a lock, so it
wouldn't have to spin..)
Thanks,
Ohad.
[1] http://en.wikipedia.org/wiki/Peterson's_algorithm
[2] http://focus.ti.com/docs/prod/folders/print/tms320c6474.html
> To me it sounds reasonable, but both ways (framework / omap-specific
> driver) will work for us just fine, and I can switch back to a misc
> driver if this is preferred.
>
> The complete discussion of v1 is at:
> http://comments.gmane.org/gmane.linux.kernel/1049802
>
> We also discussed this at v2 of the patches with David, see the
> complete discussion at:
> http://comments.gmane.org/gmane.linux.kernel/1067016
>
> Thanks,
> Ohad.
>
>>
>> thanks,
>>
>> greg k-h
>>
>
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-14 18:40 ` Ohad Ben-Cohen
@ 2010-12-16 21:08 ` Greg KH
-1 siblings, 0 replies; 40+ messages in thread
From: Greg KH @ 2010-12-16 21:08 UTC (permalink / raw)
To: Ohad Ben-Cohen
Cc: linux-omap, linux-kernel, linux-arm-kernel, akpm, Tony Lindgren,
Benoit Cousson, Grant Likely, Hari Kanigeri, Suman Anna,
Kevin Hilman, Arnd Bergmann
On Tue, Dec 14, 2010 at 08:40:28PM +0200, Ohad Ben-Cohen wrote:
> On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
> >> Can you please have a look and say if this looks OK ?
> >
> > Look at what, I don't see a patch here.
>
> Here's the complete patchset:
>
> http://www.mail-archive.com/linux-omap@vger.kernel.org/msg39833.html
>
> If you prefer, I can resubmit.
>
> >
> > I've seen a lot of discussion about this, are all of the review comments
> > now addressed?
>
> Yes, all comments were addressed in this v3 iteration, and this thread
> has been idle for about 10 days.
That's because we are all busy with other things :(
Sorry, I really don't have the time at the moment to review this code,
nor does it seem to affect areas that I maintain, so I don't understand
what you are looking for from me.
confused,
greg k-h
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-16 21:08 ` Greg KH
0 siblings, 0 replies; 40+ messages in thread
From: Greg KH @ 2010-12-16 21:08 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Dec 14, 2010 at 08:40:28PM +0200, Ohad Ben-Cohen wrote:
> On Tue, Dec 14, 2010 at 7:06 PM, Greg KH <greg@kroah.com> wrote:
> >> Can you please have a look and say if this looks OK ?
> >
> > Look at what, I don't see a patch here.
>
> Here's the complete patchset:
>
> http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39833.html
>
> If you prefer, I can resubmit.
>
> >
> > I've seen a lot of discussion about this, are all of the review comments
> > now addressed?
>
> Yes, all comments were addressed in this v3 iteration, and this thread
> has been idle for about 10 days.
That's because we are all busy with other things :(
Sorry, I really don't have the time at the moment to review this code,
nor does it seem to affect areas that I maintain, so I don't understand
what you are looking for from me.
confused,
greg k-h
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-16 21:08 ` Greg KH
@ 2010-12-16 21:34 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-16 21:34 UTC (permalink / raw)
To: Greg KH, Tony Lindgren, akpm
Cc: linux-omap, linux-kernel, linux-arm-kernel, Benoit Cousson,
Grant Likely, Hari Kanigeri, Suman Anna, Kevin Hilman,
Arnd Bergmann
On Thu, Dec 16, 2010 at 11:08 PM, Greg KH <greg@kroah.com> wrote:
>> > I've seen a lot of discussion about this, are all of the review comments
>> > now addressed?
>>
>> Yes, all comments were addressed in this v3 iteration, and this thread
>> has been idle for about 10 days.
>
> That's because we are all busy with other things :(
Oh sure, my intention was only positive (to demonstrate that there are
no outstanding comments), sorry if it sounded differently than
intended.
> Sorry, I really don't have the time at the moment to review this code,
> nor does it seem to affect areas that I maintain, so I don't understand
> what you are looking for from me.
Sorry for the noise - I contacted you because you maintain the driver
core, in the hope you could suggest where this can go through.
Tony, Andrew, can you please have a look ?
Any comment or suggestion is appreciated.
Thanks,
Ohad.
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-16 21:34 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2010-12-16 21:34 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Dec 16, 2010 at 11:08 PM, Greg KH <greg@kroah.com> wrote:
>> > I've seen a lot of discussion about this, are all of the review comments
>> > now addressed?
>>
>> Yes, all comments were addressed in this v3 iteration, and this thread
>> has been idle for about 10 days.
>
> That's because we are all busy with other things :(
Oh sure, my intention was only positive (to demonstrate that there are
no outstanding comments), sorry if it sounded differently than
intended.
> Sorry, I really don't have the time at the moment to review this code,
> nor does it seem to affect areas that I maintain, so I don't understand
> what you are looking for from me.
Sorry for the noise - I contacted you because you maintain the driver
core, in the hope you could suggest where this can go through.
Tony, Andrew, can you please have a look ?
Any comment or suggestion is appreciated.
Thanks,
Ohad.
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-16 21:34 ` Ohad Ben-Cohen
@ 2010-12-18 0:53 ` Tony Lindgren
-1 siblings, 0 replies; 40+ messages in thread
From: Tony Lindgren @ 2010-12-18 0:53 UTC (permalink / raw)
To: Ohad Ben-Cohen
Cc: Greg KH, akpm, linux-omap, linux-kernel, linux-arm-kernel,
Benoit Cousson, Grant Likely, Hari Kanigeri, Suman Anna,
Kevin Hilman, Arnd Bergmann
* Ohad Ben-Cohen <ohad@wizery.com> [101216 13:34]:
> On Thu, Dec 16, 2010 at 11:08 PM, Greg KH <greg@kroah.com> wrote:
> >> > I've seen a lot of discussion about this, are all of the review comments
> >> > now addressed?
> >>
> >> Yes, all comments were addressed in this v3 iteration, and this thread
> >> has been idle for about 10 days.
> >
> > That's because we are all busy with other things :(
>
> Oh sure, my intention was only positive (to demonstrate that there are
> no outstanding comments), sorry if it sounded differently than
> intended.
>
> > Sorry, I really don't have the time at the moment to review this code,
> > nor does it seem to affect areas that I maintain, so I don't understand
> > what you are looking for from me.
>
> Sorry for the noise - I contacted you because you maintain the driver
> core, in the hope you could suggest where this can go through.
>
> Tony, Andrew, can you please have a look ?
>
> Any comment or suggestion is appreciated.
Looks sane to me from omap point of view and it seems the locks
are now all timeout based:
Acked-by: Tony Lindgren <tony@atomide.com>
Regards,
Tony
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2010-12-18 0:53 ` Tony Lindgren
0 siblings, 0 replies; 40+ messages in thread
From: Tony Lindgren @ 2010-12-18 0:53 UTC (permalink / raw)
To: linux-arm-kernel
* Ohad Ben-Cohen <ohad@wizery.com> [101216 13:34]:
> On Thu, Dec 16, 2010 at 11:08 PM, Greg KH <greg@kroah.com> wrote:
> >> > I've seen a lot of discussion about this, are all of the review comments
> >> > now addressed?
> >>
> >> Yes, all comments were addressed in this v3 iteration, and this thread
> >> has been idle for about 10 days.
> >
> > That's because we are all busy with other things :(
>
> Oh sure, my intention was only positive (to demonstrate that there are
> no outstanding comments), sorry if it sounded differently than
> intended.
>
> > Sorry, I really don't have the time at the moment to review this code,
> > nor does it seem to affect areas that I maintain, so I don't understand
> > what you are looking for from me.
>
> Sorry for the noise - I contacted you because you maintain the driver
> core, in the hope you could suggest where this can go through.
>
> Tony, Andrew, can you please have a look ?
>
> Any comment or suggestion is appreciated.
Looks sane to me from omap point of view and it seems the locks
are now all timeout based:
Acked-by: Tony Lindgren <tony@atomide.com>
Regards,
Tony
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2010-12-18 0:53 ` Tony Lindgren
@ 2011-01-04 12:23 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2011-01-04 12:23 UTC (permalink / raw)
To: akpm
Cc: Tony Lindgren, Greg KH, linux-omap, linux-kernel,
linux-arm-kernel, Benoit Cousson, Grant Likely, Hari Kanigeri,
Suman Anna, Kevin Hilman, Arnd Bergmann
Hi Andrew,
On Sat, Dec 18, 2010 at 2:53 AM, Tony Lindgren <tony@atomide.com> wrote:
> * Ohad Ben-Cohen <ohad@wizery.com> [101216 13:34]:
>> Tony, Andrew, can you please have a look ?
>>
>> Any comment or suggestion is appreciated.
>
> Looks sane to me from omap point of view and it seems the locks
> are now all timeout based:
>
> Acked-by: Tony Lindgren <tony@atomide.com>
Can you please have a look at this patch set (see link no. [1] below) ?
Short summary:
This hwspinlock framework adds support for hardware-based locking
devices, needed to accomplish synchronization and mutual exclusion
operations between remote processors that have no alternative
mechanism to do so.
This patch set adds a framework and an OMAP implementation. It had
circulated several times in the relevant mailing lists, and all
comments were addressed. The third version of this patch set [1] was
submitted about a month ago and so far there is no outstanding
comment.
Users for this framework that we are aware of:
1. OMAP4 and Davinci Netra (DM8168): both of these SoC have the same
hwspinlock module and will share the same host implementation.
2. Other platforms (such as omap3530 and omapl1xx) that have no such
hardware support, but would still need to achieve synchronization (to
communicate with their DSP).
The only way to achieve mutual exclusion on those platforms is by
using a shared-memory synchronization algorithm called Peterson's
Algorithm [2].
We would still need the same hwspinlock framework for that - the busy
looping, the timeout, the various locking schemes, the lock resource
allocation - are all still valid. The only difference would be the
actual lock implementation, therefore we will add another host
implementation
for these platforms.
3. The C6474, a multi-core DSP device [3], have Linux running on one
of its cores, and hardware support for synchronization (btw the C6474
has a richer hardware module that would need more than the hwspinlock
framework offer today - it also supports queuing, owner semantics and
interrupt notification to let a processor know when it acquires a
lock, so it wouldn't have to spin..). Disclaimer: it will probably
take some time until c6x support is merged upstream, but this is
something that is being actively worked on [4].
Any comment or suggestion is appreciated.
Thanks,
Ohad.
[1] http://www.mail-archive.com/linux-omap@vger.kernel.org/msg39833.html
[2] http://en.wikipedia.org/wiki/Peterson's_algorithm
[3] http://focus.ti.com/docs/prod/folders/print/tms320c6474.html
[4] http://www.linux-c6x.org/wiki/index.php/Main_Page
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2011-01-04 12:23 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2011-01-04 12:23 UTC (permalink / raw)
To: linux-arm-kernel
Hi Andrew,
On Sat, Dec 18, 2010 at 2:53 AM, Tony Lindgren <tony@atomide.com> wrote:
> * Ohad Ben-Cohen <ohad@wizery.com> [101216 13:34]:
>> Tony, Andrew, can you please have a look ?
>>
>> Any comment or suggestion is appreciated.
>
> Looks sane to me from omap point of view and it seems the locks
> are now all timeout based:
>
> Acked-by: Tony Lindgren <tony@atomide.com>
Can you please have a look at this patch set (see link no. [1] below) ?
Short summary:
This hwspinlock framework adds support for hardware-based locking
devices, needed to accomplish synchronization and mutual exclusion
operations between remote processors that have no alternative
mechanism to do so.
This patch set adds a framework and an OMAP implementation. It had
circulated several times in the relevant mailing lists, and all
comments were addressed. The third version of this patch set [1] was
submitted about a month ago and so far there is no outstanding
comment.
Users for this framework that we are aware of:
1. OMAP4 and Davinci Netra (DM8168): both of these SoC have the same
hwspinlock module and will share the same host implementation.
2. Other platforms (such as omap3530 and omapl1xx) that have no such
hardware support, but would still need to achieve synchronization (to
communicate with their DSP).
The only way to achieve mutual exclusion on those platforms is by
using a shared-memory synchronization algorithm called Peterson's
Algorithm [2].
We would still need the same hwspinlock framework for that - the busy
looping, the timeout, the various locking schemes, the lock resource
allocation - are all still valid. The only difference would be the
actual lock implementation, therefore we will add another host
implementation
for these platforms.
3. The C6474, a multi-core DSP device [3], have Linux running on one
of its cores, and hardware support for synchronization (btw the C6474
has a richer hardware module that would need more than the hwspinlock
framework offer today - it also supports queuing, owner semantics and
interrupt notification to let a processor know when it acquires a
lock, so it wouldn't have to spin..). Disclaimer: it will probably
take some time until c6x support is merged upstream, but this is
something that is being actively worked on [4].
Any comment or suggestion is appreciated.
Thanks,
Ohad.
[1] http://www.mail-archive.com/linux-omap at vger.kernel.org/msg39833.html
[2] http://en.wikipedia.org/wiki/Peterson's_algorithm
[3] http://focus.ti.com/docs/prod/folders/print/tms320c6474.html
[4] http://www.linux-c6x.org/wiki/index.php/Main_Page
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2011-01-04 12:23 ` Ohad Ben-Cohen
@ 2011-01-04 20:19 ` Andrew Morton
-1 siblings, 0 replies; 40+ messages in thread
From: Andrew Morton @ 2011-01-04 20:19 UTC (permalink / raw)
To: Ohad Ben-Cohen
Cc: Tony Lindgren, Greg KH, linux-omap, linux-kernel,
linux-arm-kernel, Benoit Cousson, Grant Likely, Hari Kanigeri,
Suman Anna, Kevin Hilman, Arnd Bergmann
On Tue, 4 Jan 2011 14:23:20 +0200
Ohad Ben-Cohen <ohad@wizery.com> wrote:
> Hi Andrew,
>
> On Sat, Dec 18, 2010 at 2:53 AM, Tony Lindgren <tony@atomide.com> wrote:
> > * Ohad Ben-Cohen <ohad@wizery.com> [101216 13:34]:
> >> Tony, Andrew, can you please have a look ?
> >>
> >> Any comment or suggestion is appreciated.
> >
> > Looks sane to me from omap point of view and it seems the locks
> > are now all timeout based:
> >
> > Acked-by: Tony Lindgren <tony@atomide.com>
>
> Can you please have a look at this patch set (see link no. [1] below) ?
I looked - it looks reasonable. This is exactly the wrong time to be
looking at large new patchsets - please refresh, retest and resend
after -rc1 is released?
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2011-01-04 20:19 ` Andrew Morton
0 siblings, 0 replies; 40+ messages in thread
From: Andrew Morton @ 2011-01-04 20:19 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, 4 Jan 2011 14:23:20 +0200
Ohad Ben-Cohen <ohad@wizery.com> wrote:
> Hi Andrew,
>
> On Sat, Dec 18, 2010 at 2:53 AM, Tony Lindgren <tony@atomide.com> wrote:
> > * Ohad Ben-Cohen <ohad@wizery.com> [101216 13:34]:
> >> Tony, Andrew, can you please have a look ?
> >>
> >> Any comment or suggestion is appreciated.
> >
> > Looks sane to me from omap point of view and it seems the locks
> > are now all timeout based:
> >
> > Acked-by: Tony Lindgren <tony@atomide.com>
>
> Can you please have a look at this patch set (see link no. [1] below) ?
I looked - it looks reasonable. This is exactly the wrong time to be
looking at large new patchsets - please refresh, retest and resend
after -rc1 is released?
^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3 0/4] Introduce hardware spinlock framework
2011-01-04 20:19 ` Andrew Morton
@ 2011-01-04 20:42 ` Ohad Ben-Cohen
-1 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2011-01-04 20:42 UTC (permalink / raw)
To: Andrew Morton
Cc: Tony Lindgren, Greg KH, linux-omap, linux-kernel,
linux-arm-kernel, Benoit Cousson, Grant Likely, Hari Kanigeri,
Suman Anna, Kevin Hilman, Arnd Bergmann
On Tue, Jan 4, 2011 at 10:19 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>> > Acked-by: Tony Lindgren <tony@atomide.com>
>>
>> Can you please have a look at this patch set (see link no. [1] below) ?
>
> I looked - it looks reasonable. This is exactly the wrong time to be
> looking at large new patchsets - please refresh, retest and resend
> after -rc1 is released?
Sure, thanks !
^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3 0/4] Introduce hardware spinlock framework
@ 2011-01-04 20:42 ` Ohad Ben-Cohen
0 siblings, 0 replies; 40+ messages in thread
From: Ohad Ben-Cohen @ 2011-01-04 20:42 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, Jan 4, 2011 at 10:19 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>> > Acked-by: Tony Lindgren <tony@atomide.com>
>>
>> Can you please have a look at this patch set (see link no. [1] below) ?
>
> I looked - it looks reasonable. ?This is exactly the wrong time to be
> looking at large new patchsets - please refresh, retest and resend
> after -rc1 is released?
Sure, thanks !
^ permalink raw reply [flat|nested] 40+ messages in thread
end of thread, other threads:[~2011-01-04 20:43 UTC | newest]
Thread overview: 40+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-12-03 23:50 [PATCH v3 0/4] Introduce hardware spinlock framework Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` [PATCH v3 1/4] drivers: hwspinlock: add framework Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` [PATCH v3 2/4] drivers: hwspinlock: add OMAP implementation Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` [PATCH v3 3/4] OMAP4: hwmod data: Add hwspinlock Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` [PATCH v3 4/4] omap: add hwspinlock device Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-03 23:50 ` Ohad Ben-Cohen
2010-12-04 0:29 ` [PATCH v3 0/4] Introduce hardware spinlock framework David Daney
2010-12-04 1:28 ` Ohad Ben-Cohen
2010-12-04 1:28 ` Ohad Ben-Cohen
2010-12-04 1:28 ` Ohad Ben-Cohen
2010-12-14 14:31 ` Ohad Ben-Cohen
2010-12-14 14:31 ` Ohad Ben-Cohen
2010-12-14 17:06 ` Greg KH
2010-12-14 17:06 ` Greg KH
2010-12-14 18:40 ` Ohad Ben-Cohen
2010-12-14 18:40 ` Ohad Ben-Cohen
2010-12-16 20:42 ` Ohad Ben-Cohen
2010-12-16 20:42 ` Ohad Ben-Cohen
2010-12-16 20:42 ` Ohad Ben-Cohen
2010-12-16 21:08 ` Greg KH
2010-12-16 21:08 ` Greg KH
2010-12-16 21:34 ` Ohad Ben-Cohen
2010-12-16 21:34 ` Ohad Ben-Cohen
2010-12-18 0:53 ` Tony Lindgren
2010-12-18 0:53 ` Tony Lindgren
2011-01-04 12:23 ` Ohad Ben-Cohen
2011-01-04 12:23 ` Ohad Ben-Cohen
2011-01-04 20:19 ` Andrew Morton
2011-01-04 20:19 ` Andrew Morton
2011-01-04 20:42 ` Ohad Ben-Cohen
2011-01-04 20:42 ` Ohad Ben-Cohen
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