[PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[Sudeep KarkadaNagesha]

From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

Hi Olof/Kevin,

I am reposting this series as suggested by Olof[1]. This is reviewed and
acked by Will and Catalin. Daniel needs Ack from arm-soc maintainers
to take these through his tree. Can you review this ?

Regards,
Sudeep
[1] http://www.spinics.net/lists/arm-kernel/msg270926.html
-----------

This patch series adds support to configure the rate and enable the
event stream for architected timer. The event streams can be used to
impose a timeout on a wfe, to safeguard against any programming error
in case an expected event is not generated or even to implement
wfe-based timeouts for userspace locking implementations. This feature
can be disabled(enabled by default).

Since the timer control register is reset to zero on warm boot, CPU
PM notifier is added to save and restore the value.

Changes v5->v6:
1. Disabling event stream by default on boot and enable it
   only if CONFIG_ARM_ARCH_TIMER_EVTSTREAM=y
   This removes runtime configuration of timer event stream.
2. Moved COMPAT_ELF_HWCAP_DEFAULT to arch/arm64/kernel/setup.c

Changes v4->v5:
1. Removed compat_dyn_elf_hwcap and used just compat_elf_hwcap as per
   Catalin's suggestion
2. Instead of resetting event stream in CPU PM callbacks, saving and
   restoring counter control register now.

Changes v3->v4:
1. Added a config option to en/disable the timer event stream feature.
   Due to this the ordering of the patches as well as some cosmetic
   code changes are done.( So dropped previous reviewed-by tags)
2. Removed exporting compat_dyn_elf_hwcap as there are no modules
   requiring it for now.

Changes v2->v3:
1. Moved ARM and ARM64 changes into separate patches
2. Added native hwcaps definations(ARM/ARM64) and compat-specific
   definitions(ARM64) to the users for the event stream feature. 

Changes v1->v2:
1. Saved event stream divider value on cold reset path and re-used it
   in CPU PM notifier instead of calculating every time.
2. Rebased on v3.11-rc2(to avoid conflicts with __cpuinit* deletion)
3. Dropped "ARM/ARM64: arch_timer: remove __cpuinit attribute for
   arch_counter_set_user_access"(already done as part of __cpuinit*
   deletion)

Sudeep KarkadaNagesha (4):
  ARM/ARM64: arch_timer: add macros for bits in control register
  ARM: arch_timer: add support to configure and enable event stream
  ARM64: arch_timer: add support to configure and enable event stream
  drivers: clocksource: add CPU PM notifier for ARM architected timer

Will Deacon (1):
  drivers: clocksource: add support for ARM architected timer event
    stream

 arch/arm/include/asm/arch_timer.h    | 36 ++++++++++++++++++++++----
 arch/arm/include/uapi/asm/hwcap.h    |  1 +
 arch/arm/kernel/setup.c              |  1 +
 arch/arm64/include/asm/arch_timer.h  | 42 ++++++++++++++++++++++++++-----
 arch/arm64/include/asm/hwcap.h       | 11 ++++----
 arch/arm64/include/uapi/asm/hwcap.h  |  1 +
 arch/arm64/kernel/setup.c            | 11 ++++++++
 drivers/clocksource/Kconfig          | 15 +++++++++++
 drivers/clocksource/arm_arch_timer.c | 49 ++++++++++++++++++++++++++++++++++++
 include/clocksource/arm_arch_timer.h | 10 ++++++++
 10 files changed, 161 insertions(+), 16 deletions(-)

-- 
1.8.1.2

[PATCH v6 RESEND 1/5] ARM/ARM64: arch_timer: add macros for bits in control register

[Sudeep KarkadaNagesha]

From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

Add macros to describe the bitfields in the ARM architected timer
control register to make code easy to understand.

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
---
 arch/arm/include/asm/arch_timer.h    |  9 +++++++--
 arch/arm64/include/asm/arch_timer.h  | 12 ++++++++----
 include/clocksource/arm_arch_timer.h |  8 ++++++++
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 5665134..d57e04d 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -93,8 +93,13 @@ static inline void arch_counter_set_user_access(void)
 
 	asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));
 
-	/* disable user access to everything */
-	cntkctl &= ~((3 << 8) | (7 << 0));
+	/* Disable user access to both physical/virtual counters/timers */
+	/* Also disable virtual event stream */
+	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
+			| ARCH_TIMER_USR_VT_ACCESS_EN
+			| ARCH_TIMER_VIRT_EVT_EN
+			| ARCH_TIMER_USR_VCT_ACCESS_EN
+			| ARCH_TIMER_USR_PCT_ACCESS_EN);
 
 	asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
 }
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index c9f1d28..2b9722f 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -96,12 +96,16 @@ static inline void arch_counter_set_user_access(void)
 {
 	u32 cntkctl;
 
-	/* Disable user access to the timers and the physical counter. */
 	asm volatile("mrs	%0, cntkctl_el1" : "=r" (cntkctl));
-	cntkctl &= ~((3 << 8) | (1 << 0));
 
-	/* Enable user access to the virtual counter and frequency. */
-	cntkctl |= (1 << 1);
+	/* Disable user access to the timers and the physical counter */
+	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
+			| ARCH_TIMER_USR_VT_ACCESS_EN
+			| ARCH_TIMER_USR_PCT_ACCESS_EN);
+
+	/* Enable user access to the virtual counter */
+	cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
+
 	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));
 }
 
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index 93b7f96..8707dae 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -33,6 +33,14 @@ enum arch_timer_reg {
 #define ARCH_TIMER_MEM_PHYS_ACCESS	2
 #define ARCH_TIMER_MEM_VIRT_ACCESS	3
 
+#define ARCH_TIMER_USR_PCT_ACCESS_EN	(1 << 0) /* physical counter */
+#define ARCH_TIMER_USR_VCT_ACCESS_EN	(1 << 1) /* virtual counter */
+#define ARCH_TIMER_VIRT_EVT_EN		(1 << 2)
+#define ARCH_TIMER_EVT_TRIGGER_SHIFT	(4)
+#define ARCH_TIMER_EVT_TRIGGER_MASK	(0xF << ARCH_TIMER_EVT_TRIGGER_SHIFT)
+#define ARCH_TIMER_USR_VT_ACCESS_EN	(1 << 8) /* virtual timer registers */
+#define ARCH_TIMER_USR_PT_ACCESS_EN	(1 << 9) /* physical timer registers */
+
 #ifdef CONFIG_ARM_ARCH_TIMER
 
 extern u32 arch_timer_get_rate(void);
-- 
1.8.1.2

[PATCH v6 RESEND 2/5] ARM: arch_timer: add support to configure and enable event stream

[Sudeep KarkadaNagesha]

From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

This patch adds support for configuring the event stream frequency
and enabling it.

It also adds the hwcaps definitions to the user to detect this event
stream feature.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
---
 arch/arm/include/asm/arch_timer.h | 27 ++++++++++++++++++++++++---
 arch/arm/include/uapi/asm/hwcap.h |  1 +
 arch/arm/kernel/setup.c           |  1 +
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index d57e04d..0704e0c 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -87,11 +87,21 @@ static inline u64 arch_counter_get_cntvct(void)
 	return cval;
 }
 
-static inline void arch_counter_set_user_access(void)
+static inline u32 arch_timer_get_cntkctl(void)
 {
 	u32 cntkctl;
-
 	asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));
+	return cntkctl;
+}
+
+static inline void arch_timer_set_cntkctl(u32 cntkctl)
+{
+	asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
+}
+
+static inline void arch_counter_set_user_access(void)
+{
+	u32 cntkctl = arch_timer_get_cntkctl();
 
 	/* Disable user access to both physical/virtual counters/timers */
 	/* Also disable virtual event stream */
@@ -100,9 +110,20 @@ static inline void arch_counter_set_user_access(void)
 			| ARCH_TIMER_VIRT_EVT_EN
 			| ARCH_TIMER_USR_VCT_ACCESS_EN
 			| ARCH_TIMER_USR_PCT_ACCESS_EN);
+	arch_timer_set_cntkctl(cntkctl);
+}
 
-	asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
+static inline void arch_timer_evtstrm_enable(int divider)
+{
+	u32 cntkctl = arch_timer_get_cntkctl();
+	cntkctl &= ~ARCH_TIMER_EVT_TRIGGER_MASK;
+	/* Set the divider and enable virtual event stream */
+	cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT)
+			| ARCH_TIMER_VIRT_EVT_EN;
+	arch_timer_set_cntkctl(cntkctl);
+	elf_hwcap |= HWCAP_EVTSTRM;
 }
+
 #endif
 
 #endif
diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 6d34d08..7dcc10d 100644
--- a/arch/arm/include/uapi/asm/hwcap.h
+++ b/arch/arm/include/uapi/asm/hwcap.h
@@ -26,5 +26,6 @@
 #define HWCAP_VFPD32	(1 << 19)	/* set if VFP has 32 regs (not 16) */
 #define HWCAP_IDIV	(HWCAP_IDIVA | HWCAP_IDIVT)
 #define HWCAP_LPAE	(1 << 20)
+#define HWCAP_EVTSTRM	(1 << 21)
 
 #endif /* _UAPI__ASMARM_HWCAP_H */
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 0e1e2b3..5d65438 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -975,6 +975,7 @@ static const char *hwcap_str[] = {
 	"idivt",
 	"vfpd32",
 	"lpae",
+	"evtstrm",
 	NULL
 };
 
-- 
1.8.1.2

[PATCH v6 RESEND 3/5] ARM64: arch_timer: add support to configure and enable event stream

[Sudeep KarkadaNagesha]

From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

This patch adds support for configuring the event stream frequency
and enabling it.

It also adds the hwcaps as well as compat-specific definitions to
the user to detect this event stream feature.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
---
 arch/arm64/include/asm/arch_timer.h | 32 +++++++++++++++++++++++++++++---
 arch/arm64/include/asm/hwcap.h      | 11 ++++++-----
 arch/arm64/include/uapi/asm/hwcap.h |  1 +
 arch/arm64/kernel/setup.c           | 11 +++++++++++
 4 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 2b9722f..9400596 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -92,21 +92,47 @@ static inline u32 arch_timer_get_cntfrq(void)
 	return val;
 }
 
-static inline void arch_counter_set_user_access(void)
+static inline u32 arch_timer_get_cntkctl(void)
 {
 	u32 cntkctl;
-
 	asm volatile("mrs	%0, cntkctl_el1" : "=r" (cntkctl));
+	return cntkctl;
+}
+
+static inline void arch_timer_set_cntkctl(u32 cntkctl)
+{
+	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));
+}
+
+static inline void arch_counter_set_user_access(void)
+{
+	u32 cntkctl = arch_timer_get_cntkctl();
 
 	/* Disable user access to the timers and the physical counter */
+	/* Also disable virtual event stream */
 	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
 			| ARCH_TIMER_USR_VT_ACCESS_EN
+			| ARCH_TIMER_VIRT_EVT_EN
 			| ARCH_TIMER_USR_PCT_ACCESS_EN);
 
 	/* Enable user access to the virtual counter */
 	cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
 
-	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));
+	arch_timer_set_cntkctl(cntkctl);
+}
+
+static inline void arch_timer_evtstrm_enable(int divider)
+{
+	u32 cntkctl = arch_timer_get_cntkctl();
+	cntkctl &= ~ARCH_TIMER_EVT_TRIGGER_MASK;
+	/* Set the divider and enable virtual event stream */
+	cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT)
+			| ARCH_TIMER_VIRT_EVT_EN;
+	arch_timer_set_cntkctl(cntkctl);
+	elf_hwcap |= HWCAP_EVTSTRM;
+#ifdef CONFIG_COMPAT
+	compat_elf_hwcap |= COMPAT_HWCAP_EVTSTRM;
+#endif
 }
 
 static inline u64 arch_counter_get_cntvct(void)
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 6d4482f..3a48433 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -30,6 +30,7 @@
 #define COMPAT_HWCAP_IDIVA	(1 << 17)
 #define COMPAT_HWCAP_IDIVT	(1 << 18)
 #define COMPAT_HWCAP_IDIV	(COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT)
+#define COMPAT_HWCAP_EVTSTRM	(1 << 21)
 
 #ifndef __ASSEMBLY__
 /*
@@ -37,11 +38,11 @@
  * instruction set this cpu supports.
  */
 #define ELF_HWCAP		(elf_hwcap)
-#define COMPAT_ELF_HWCAP	(COMPAT_HWCAP_HALF|COMPAT_HWCAP_THUMB|\
-				 COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\
-				 COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\
-				 COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\
-				 COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV)
+
+#ifdef CONFIG_COMPAT
+#define COMPAT_ELF_HWCAP	(compat_elf_hwcap)
+extern unsigned int compat_elf_hwcap;
+#endif
 
 extern unsigned int elf_hwcap;
 #endif
diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
index eea4975..9b12476 100644
--- a/arch/arm64/include/uapi/asm/hwcap.h
+++ b/arch/arm64/include/uapi/asm/hwcap.h
@@ -21,6 +21,7 @@
  */
 #define HWCAP_FP		(1 << 0)
 #define HWCAP_ASIMD		(1 << 1)
+#define HWCAP_EVTSTRM		(1 << 2)
 
 
 #endif /* _UAPI__ASM_HWCAP_H */
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 12ad8f3..c539e5f 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -60,6 +60,16 @@ EXPORT_SYMBOL(processor_id);
 unsigned int elf_hwcap __read_mostly;
 EXPORT_SYMBOL_GPL(elf_hwcap);
 
+#ifdef CONFIG_COMPAT
+#define COMPAT_ELF_HWCAP_DEFAULT	\
+				(COMPAT_HWCAP_HALF|COMPAT_HWCAP_THUMB|\
+				 COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\
+				 COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\
+				 COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\
+				 COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV)
+unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
+#endif
+
 static const char *cpu_name;
 static const char *machine_name;
 phys_addr_t __fdt_pointer __initdata;
@@ -304,6 +314,7 @@ subsys_initcall(topology_init);
 static const char *hwcap_str[] = {
 	"fp",
 	"asimd",
+	"evtstrm",
 	NULL
 };
 
-- 
1.8.1.2

[PATCH v6 RESEND 4/5] drivers: clocksource: add support for ARM architected timer event stream

[Sudeep KarkadaNagesha]

From: Will Deacon <will.deacon@arm.com>

The ARM architected timer can generate events (used for waking up
CPUs executing the wfe instruction) at a frequency represented as a
power-of-2 divisor of the clock rate.

An event stream might be used:
- To implement wfe-based timeouts for userspace locking implementations.
- To impose a timeout on a wfe for safeguarding against any programming
  error in case an expected event is not generated.

This patch computes the event stream frequency aiming for a period
of 100us between events. It uses ARM/ARM64 specific backends to configure
and enable the event stream.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[sudeep: moving ARM/ARM64 changes into separate patches
         and adding Kconfig option]
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
---
 drivers/clocksource/Kconfig          | 15 +++++++++++++++
 drivers/clocksource/arm_arch_timer.c | 15 +++++++++++++++
 include/clocksource/arm_arch_timer.h |  2 ++
 3 files changed, 32 insertions(+)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 41c6946..559d803 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -74,6 +74,21 @@ config ARM_ARCH_TIMER
 	bool
 	select CLKSRC_OF if OF
 
+config ARM_ARCH_TIMER_EVTSTREAM
+	bool "Support for ARM architected timer event stream generation"
+	default y if ARM_ARCH_TIMER
+	help
+	  This option enables support for event stream generation based on
+	  the ARM architected timer. It is used for waking up CPUs executing
+	  the wfe instruction at a frequency represented as a power-of-2
+	  divisor of the clock rate.
+	  The main use of the event stream is wfe-based timeouts of userspace
+	  locking implementations. It might also be useful for imposing timeout
+	  on wfe to safeguard against any programming errors in case an expected
+	  event is not generated.
+	  This must be disabled for hardware validation purposes to detect any
+	  hardware anomalies of missing events.
+
 config ARM_GLOBAL_TIMER
 	bool
 	select CLKSRC_OF if OF
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index fbd9ccd..105f8ff 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -294,6 +294,19 @@ static void __arch_timer_setup(unsigned type,
 	clockevents_config_and_register(clk, arch_timer_rate, 0xf, 0x7fffffff);
 }
 
+static void arch_timer_configure_evtstream(void)
+{
+	int evt_stream_div, pos;
+
+	/* Find the closest power of two to the divisor */
+	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ;
+	pos = fls(evt_stream_div);
+	if (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))
+		pos--;
+	/* enable event stream */
+	arch_timer_evtstrm_enable(min(pos, 15));
+}
+
 static int arch_timer_setup(struct clock_event_device *clk)
 {
 	__arch_timer_setup(ARCH_CP15_TIMER, clk);
@@ -307,6 +320,8 @@ static int arch_timer_setup(struct clock_event_device *clk)
 	}
 
 	arch_counter_set_user_access();
+	if (IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM))
+		arch_timer_configure_evtstream();
 
 	return 0;
 }
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index 8707dae..6d26b40 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -41,6 +41,8 @@ enum arch_timer_reg {
 #define ARCH_TIMER_USR_VT_ACCESS_EN	(1 << 8) /* virtual timer registers */
 #define ARCH_TIMER_USR_PT_ACCESS_EN	(1 << 9) /* physical timer registers */
 
+#define ARCH_TIMER_EVT_STREAM_FREQ	10000	/* 100us */
+
 #ifdef CONFIG_ARM_ARCH_TIMER
 
 extern u32 arch_timer_get_rate(void);
-- 
1.8.1.2

[PATCH v6 RESEND 5/5] drivers: clocksource: add CPU PM notifier for ARM architected timer

[Sudeep KarkadaNagesha]

From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

Few control settings done in architected timer as part of initialisation
can be lost when CPU enters deeper power states. They need to be
restored when the CPU is (warm)reset again.

This patch adds CPU PM notifiers to save the counter control register
when entering low power modes and restore it when CPU exits low power.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
---
 drivers/clocksource/arm_arch_timer.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 105f8ff..9338f1a 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -13,6 +13,7 @@
 #include <linux/device.h>
 #include <linux/smp.h>
 #include <linux/cpu.h>
+#include <linux/cpu_pm.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
@@ -475,6 +476,33 @@ static struct notifier_block arch_timer_cpu_nb = {
 	.notifier_call = arch_timer_cpu_notify,
 };
 
+#ifdef CONFIG_CPU_PM
+static unsigned int saved_cntkctl;
+static int arch_timer_cpu_pm_notify(struct notifier_block *self,
+				    unsigned long action, void *hcpu)
+{
+	if (action == CPU_PM_ENTER)
+		saved_cntkctl = arch_timer_get_cntkctl();
+	else if (action == CPU_PM_ENTER_FAILED || action == CPU_PM_EXIT)
+		arch_timer_set_cntkctl(saved_cntkctl);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block arch_timer_cpu_pm_notifier = {
+	.notifier_call = arch_timer_cpu_pm_notify,
+};
+
+static int __init arch_timer_cpu_pm_init(void)
+{
+	return cpu_pm_register_notifier(&arch_timer_cpu_pm_notifier);
+}
+#else
+static int __init arch_timer_cpu_pm_init(void)
+{
+	return 0;
+}
+#endif
+
 static int __init arch_timer_register(void)
 {
 	int err;
@@ -514,11 +542,17 @@ static int __init arch_timer_register(void)
 	if (err)
 		goto out_free_irq;
 
+	err = arch_timer_cpu_pm_init();
+	if (err)
+		goto out_unreg_notify;
+
 	/* Immediately configure the timer on the boot CPU */
 	arch_timer_setup(this_cpu_ptr(arch_timer_evt));
 
 	return 0;
 
+out_unreg_notify:
+	unregister_cpu_notifier(&arch_timer_cpu_nb);
 out_free_irq:
 	if (arch_timer_use_virtual)
 		free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
-- 
1.8.1.2

Re: [PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[Daniel Lezcano]

On 09/18/2013 01:05 PM, Sudeep KarkadaNagesha wrote:
> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
> 
> Hi Olof/Kevin,

Added Olof and Kevin in Cc.

> I am reposting this series as suggested by Olof[1]. This is reviewed and
> acked by Will and Catalin. Daniel needs Ack from arm-soc maintainers
> to take these through his tree. Can you review this ?
> 
> Regards,
> Sudeep
> [1] http://www.spinics.net/lists/arm-kernel/msg270926.html
> -----------
> 
> This patch series adds support to configure the rate and enable the
> event stream for architected timer. The event streams can be used to
> impose a timeout on a wfe, to safeguard against any programming error
> in case an expected event is not generated or even to implement
> wfe-based timeouts for userspace locking implementations. This feature
> can be disabled(enabled by default).
> 
> Since the timer control register is reset to zero on warm boot, CPU
> PM notifier is added to save and restore the value.
> 
> Changes v5->v6:
> 1. Disabling event stream by default on boot and enable it
>    only if CONFIG_ARM_ARCH_TIMER_EVTSTREAM=y
>    This removes runtime configuration of timer event stream.
> 2. Moved COMPAT_ELF_HWCAP_DEFAULT to arch/arm64/kernel/setup.c
> 
> Changes v4->v5:
> 1. Removed compat_dyn_elf_hwcap and used just compat_elf_hwcap as per
>    Catalin's suggestion
> 2. Instead of resetting event stream in CPU PM callbacks, saving and
>    restoring counter control register now.
> 
> Changes v3->v4:
> 1. Added a config option to en/disable the timer event stream feature.
>    Due to this the ordering of the patches as well as some cosmetic
>    code changes are done.( So dropped previous reviewed-by tags)
> 2. Removed exporting compat_dyn_elf_hwcap as there are no modules
>    requiring it for now.
> 
> Changes v2->v3:
> 1. Moved ARM and ARM64 changes into separate patches
> 2. Added native hwcaps definations(ARM/ARM64) and compat-specific
>    definitions(ARM64) to the users for the event stream feature. 
> 
> Changes v1->v2:
> 1. Saved event stream divider value on cold reset path and re-used it
>    in CPU PM notifier instead of calculating every time.
> 2. Rebased on v3.11-rc2(to avoid conflicts with __cpuinit* deletion)
> 3. Dropped "ARM/ARM64: arch_timer: remove __cpuinit attribute for
>    arch_counter_set_user_access"(already done as part of __cpuinit*
>    deletion)
> 
> Sudeep KarkadaNagesha (4):
>   ARM/ARM64: arch_timer: add macros for bits in control register
>   ARM: arch_timer: add support to configure and enable event stream
>   ARM64: arch_timer: add support to configure and enable event stream
>   drivers: clocksource: add CPU PM notifier for ARM architected timer
> 
> Will Deacon (1):
>   drivers: clocksource: add support for ARM architected timer event
>     stream
> 
>  arch/arm/include/asm/arch_timer.h    | 36 ++++++++++++++++++++++----
>  arch/arm/include/uapi/asm/hwcap.h    |  1 +
>  arch/arm/kernel/setup.c              |  1 +
>  arch/arm64/include/asm/arch_timer.h  | 42 ++++++++++++++++++++++++++-----
>  arch/arm64/include/asm/hwcap.h       | 11 ++++----
>  arch/arm64/include/uapi/asm/hwcap.h  |  1 +
>  arch/arm64/kernel/setup.c            | 11 ++++++++
>  drivers/clocksource/Kconfig          | 15 +++++++++++
>  drivers/clocksource/arm_arch_timer.c | 49 ++++++++++++++++++++++++++++++++++++
>  include/clocksource/arm_arch_timer.h | 10 ++++++++
>  10 files changed, 161 insertions(+), 16 deletions(-)
> 


-- 
 <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

Re: [PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[Sudeep KarkadaNagesha]

On 25/09/13 16:06, Daniel Lezcano wrote:
> On 09/18/2013 01:05 PM, Sudeep KarkadaNagesha wrote:
>> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
>>
>> Hi Olof/Kevin,
> 
> Added Olof and Kevin in Cc.
> 
Thanks Daniel, sorry I assumed mailing list alias(arm@kernel.org) was preferred way.

Regards,
Sudeep

Re: [PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[Olof Johansson]

On Wed, Sep 18, 2013 at 12:05:01PM +0100, Sudeep KarkadaNagesha wrote:
> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
> 
> Hi Olof/Kevin,
> 
> I am reposting this series as suggested by Olof[1]. This is reviewed and
> acked by Will and Catalin. Daniel needs Ack from arm-soc maintainers
> to take these through his tree. Can you review this ?

Acked-by: Olof Johansson <olof@lixom.net>

Sorry for the delay.


-Olof

Re: [PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[Arnd Bergmann]

On Wednesday 25 September 2013, Sudeep KarkadaNagesha wrote:
> On 25/09/13 16:06, Daniel Lezcano wrote:
> > On 09/18/2013 01:05 PM, Sudeep KarkadaNagesha wrote:
> >> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
> >>
> >> Hi Olof/Kevin,
> > 
> > Added Olof and Kevin in Cc.
> > 
> Thanks Daniel, sorry I assumed mailing list alias(arm@kernel.org) was preferred way.
> 

The alias is mainly for when you are sending a pull request or a patch to
be applied directly. For any review it makes more sense to Cc the ones you
want involved directly.

	Arnd

Re: [PATCH v6 RESEND 0/5] ARM/ARM64 architected timer updates

[Sudeep KarkadaNagesha]

On 26/09/13 10:43, Arnd Bergmann wrote:
> On Wednesday 25 September 2013, Sudeep KarkadaNagesha wrote:
>> On 25/09/13 16:06, Daniel Lezcano wrote:
>>> On 09/18/2013 01:05 PM, Sudeep KarkadaNagesha wrote:
>>>> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
>>>>
>>>> Hi Olof/Kevin,
>>>
>>> Added Olof and Kevin in Cc.
>>>
>> Thanks Daniel, sorry I assumed mailing list alias(arm@kernel.org) was preferred way.
>>
> 
> The alias is mainly for when you are sending a pull request or a patch to
> be applied directly. For any review it makes more sense to Cc the ones you
> want involved directly.
> 
Thanks Arnd for clarification. I came across the same info yesterday from one of
the mails from Olof a while ago. I had a wrong assumption, sorry for that.

Regards,
Sudeep