[PATCH v6 0/7] kernel: Add support for restart handler call chain

[PATCH v6 0/7] kernel: Add support for restart handler call chain

[Guenter Roeck]

Various drivers implement architecture and/or device specific means
to restart (reset) the system. Various mechanisms have been implemented
to support those schemes. The best known mechanism is arm_pm_restart,
which is a function pointer to be set either from platform specific code
or from drivers. Another mechanism is to use hardware watchdogs to issue
a reset; this mechanism is used if there is no other method available
to reset a board or system. Two examples are alim7101_wdt, which currently
uses the reboot notifier to trigger a reset, and moxart_wdt, which registers
the arm_pm_restart function. Several other restart drivers for arm, all
directly calling arm_pm_restart, are in the process of being integrated
into the kernel. All those drivers would benefit from the new API.

The existing mechanisms have a number of drawbacks. Typically only one scheme
to restart the system is supported (at least if arm_pm_restart is used).
At least in theory there can be multiple means to restart the system, some of
which may be less desirable (for example one mechanism may only reset the CPU,
while another may reset the entire system). Using arm_pm_restart can also be
racy if the function pointer is set from a driver, as the driver may be in
the process of being unloaded when arm_pm_restart is called.
Using the reboot notifier is always racy, as it is unknown if and when
other functions using the reboot notifier have completed execution
by the time the watchdog fires.

Introduce a system restart handler call chain to solve the described problems.
This call chain is expected to be executed from the architecture specific
machine_restart() function. Drivers providing system restart functionality
(such as the watchdog drivers mentioned above) are expected to register
with this call chain. By using the priority field in the notifier block,
callers can control restart handler execution sequence and thus ensure that
the restart handler with the optimal restart capabilities for a given system
is called first.

Since the first revision of this patchset, a number of separate patch
submissions have been made which either depend on it or could make use of it.

http://www.spinics.net/linux/lists/arm-kernel/msg344796.html
	registers three notifiers.
https://lkml.org/lkml/2014/7/8/962
	would benefit from it.

Patch 1 of this series implements the restart handler function. Patches 2 and 3
implement calling the restart handler chain from arm and arm64 restart code.

Patch 4 modifies the restart-poweroff driver to no longer call arm_pm_restart
directly but machine_restart. This is done to avoid calling arm_pm_restart
from more than one place. The change makes the driver architecture independent,
so it would be possible to drop the arm dependency from its Kconfig entry.

Patch 5 and 6 convert existing restart handlers in the watchdog subsystem
to use the restart handler. Patch 7 unexports arm_pm_restart to ensure
that no one gets the idea to implement a restart handler as module.

The entire patch series, including additional patches depending on it,
is available from
https://git.kernel.org/cgit/linux/kernel/git/groeck/linux-staging.git/
in branch 'restart-staging'.

On a side note, I realize that the timing for sending this series is less
than optimal, given that we have an open commit window. Letting it sit for
two weeks collecting dust isn't optimal either, so I figure it may as well
collect dust in public.

---
v6: Use atomic notifier call chain 
    Rebased series to v3.16
v5: Rebased series to v3.16-rc5
    Function renames:
    register_restart_notifier -> register_restart_handler
    unregister_restart_notifier -> unregister_restart_handler
    kernel_restart_notify -> do_kernel_restart
v4: Document restart notifier priorities
    Select 128 as default priority for newly introduced notifiers
    Fix checkpatch warning (line too long) in moxart patch
v3: Drop RFC.
    Add kernel_restart_notify wrapper function to execute notifier
    Improve documentation.
    Move restart_notifier_list into kernel/reboot.c and make it static.
v2: Add patch 4.
    Only call blocking notifier call chain if arm_pm_restart was not set.

[PATCH v6 0/7] kernel: Add support for restart handler call chain

[Guenter Roeck]

Various drivers implement architecture and/or device specific means
to restart (reset) the system. Various mechanisms have been implemented
to support those schemes. The best known mechanism is arm_pm_restart,
which is a function pointer to be set either from platform specific code
or from drivers. Another mechanism is to use hardware watchdogs to issue
a reset; this mechanism is used if there is no other method available
to reset a board or system. Two examples are alim7101_wdt, which currently
uses the reboot notifier to trigger a reset, and moxart_wdt, which registers
the arm_pm_restart function. Several other restart drivers for arm, all
directly calling arm_pm_restart, are in the process of being integrated
into the kernel. All those drivers would benefit from the new API.

The existing mechanisms have a number of drawbacks. Typically only one scheme
to restart the system is supported (at least if arm_pm_restart is used).
At least in theory there can be multiple means to restart the system, some of
which may be less desirable (for example one mechanism may only reset the CPU,
while another may reset the entire system). Using arm_pm_restart can also be
racy if the function pointer is set from a driver, as the driver may be in
the process of being unloaded when arm_pm_restart is called.
Using the reboot notifier is always racy, as it is unknown if and when
other functions using the reboot notifier have completed execution
by the time the watchdog fires.

Introduce a system restart handler call chain to solve the described problems.
This call chain is expected to be executed from the architecture specific
machine_restart() function. Drivers providing system restart functionality
(such as the watchdog drivers mentioned above) are expected to register
with this call chain. By using the priority field in the notifier block,
callers can control restart handler execution sequence and thus ensure that
the restart handler with the optimal restart capabilities for a given system
is called first.

Since the first revision of this patchset, a number of separate patch
submissions have been made which either depend on it or could make use of it.

http://www.spinics.net/linux/lists/arm-kernel/msg344796.html
	registers three notifiers.
https://lkml.org/lkml/2014/7/8/962
	would benefit from it.

Patch 1 of this series implements the restart handler function. Patches 2 and 3
implement calling the restart handler chain from arm and arm64 restart code.

Patch 4 modifies the restart-poweroff driver to no longer call arm_pm_restart
directly but machine_restart. This is done to avoid calling arm_pm_restart
from more than one place. The change makes the driver architecture independent,
so it would be possible to drop the arm dependency from its Kconfig entry.

Patch 5 and 6 convert existing restart handlers in the watchdog subsystem
to use the restart handler. Patch 7 unexports arm_pm_restart to ensure
that no one gets the idea to implement a restart handler as module.

The entire patch series, including additional patches depending on it,
is available from
https://git.kernel.org/cgit/linux/kernel/git/groeck/linux-staging.git/
in branch 'restart-staging'.

On a side note, I realize that the timing for sending this series is less
than optimal, given that we have an open commit window. Letting it sit for
two weeks collecting dust isn't optimal either, so I figure it may as well
collect dust in public.

---
v6: Use atomic notifier call chain 
    Rebased series to v3.16
v5: Rebased series to v3.16-rc5
    Function renames:
    register_restart_notifier -> register_restart_handler
    unregister_restart_notifier -> unregister_restart_handler
    kernel_restart_notify -> do_kernel_restart
v4: Document restart notifier priorities
    Select 128 as default priority for newly introduced notifiers
    Fix checkpatch warning (line too long) in moxart patch
v3: Drop RFC.
    Add kernel_restart_notify wrapper function to execute notifier
    Improve documentation.
    Move restart_notifier_list into kernel/reboot.c and make it static.
v2: Add patch 4.
    Only call blocking notifier call chain if arm_pm_restart was not set.

[PATCH v6 1/7] kernel: Add support for kernel restart handler call chain

[Guenter Roeck]

Various drivers implement architecture and/or device specific means
to restart (reset) the system. Various mechanisms have been implemented
to support those schemes. The best known mechanism is arm_pm_restart,
which is a function pointer to be set either from platform specific code
or from drivers. Another mechanism is to use hardware watchdogs to issue
a reset; this mechanism is used if there is no other method available
to reset a board or system. Two examples are alim7101_wdt, which currently
uses the reboot notifier to trigger a reset, and moxart_wdt, which registers
the arm_pm_restart function.

The existing mechanisms have a number of drawbacks. Typically only one scheme
to restart the system is supported (at least if arm_pm_restart is used).
At least in theory there can be multiple means to restart the system, some of
which may be less desirable (for example one mechanism may only reset the CPU,
while another may reset the entire system). Using arm_pm_restart can also be
racy if the function pointer is set from a driver, as the driver may be in
the process of being unloaded when arm_pm_restart is called.
Using the reboot notifier is always racy, as it is unknown if and when
other functions using the reboot notifier have completed execution
by the time the watchdog fires.

Introduce a system restart handler call chain to solve the described problems.
This call chain is expected to be executed from the architecture specific
machine_restart() function. Drivers providing system restart functionality
(such as the watchdog drivers mentioned above) are expected to register
with this call chain. By using the priority field in the notifier block,
callers can control restart handler execution sequence and thus ensure that
the restart handler with the optimal restart capabilities for a given system
is called first.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: Use atomic notifier call chain
v5: Function renames:
    register_restart_notifier -> register_restart_handler
    unregister_restart_notifier -> unregister_restart_handler
    kernel_restart_notify -> do_kernel_restart
v4: Document and suggest values for notifier priorities
v3: Add kernel_restart_notify wrapper function to execute notifier.
    Improve documentation.
    Move restart_notifier_list into kernel/reboot.c and make it static.
v2: No change.

 include/linux/reboot.h |  3 ++
 kernel/reboot.c        | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 48bf152..67fc8fc 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -38,6 +38,9 @@ extern int reboot_force;
 extern int register_reboot_notifier(struct notifier_block *);
 extern int unregister_reboot_notifier(struct notifier_block *);
 
+extern int register_restart_handler(struct notifier_block *);
+extern int unregister_restart_handler(struct notifier_block *);
+extern void do_kernel_restart(char *cmd);
 
 /*
  * Architecture-specific implementations of sys_reboot commands.
diff --git a/kernel/reboot.c b/kernel/reboot.c
index a3a9e24..5925f5a 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -104,6 +104,87 @@ int unregister_reboot_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	to restart the system.
+ */
+static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
+
+/**
+ *	register_restart_handler - Register function to be called to reset
+ *				   the system
+ *	@nb: Info about handler function to be called
+ *	@nb->priority:	Handler priority. Handlers should follow the
+ *			following guidelines for setting priorities.
+ *			0:	Restart handler of last resort,
+ *				with limited restart capabilities
+ *			128:	Default restart handler; use if no other
+ *				restart handler is expected to be available,
+ *				and/or if restart functionality is
+ *				sufficient to restart the entire system
+ *			255:	Highest priority restart handler, will
+ *				preempt all other restart handlers
+ *
+ *	Registers a function with code to be called to restart the
+ *	system.
+ *
+ *	Registered functions will be called from machine_restart as last
+ *	step of the restart sequence (if the architecture specific
+ *	machine_restart function calls do_kernel_restart - see below
+ *	for details).
+ *	Registered functions are expected to restart the system immediately.
+ *	If more than one function is registered, the restart handler priority
+ *	selects which function will be called first.
+ *
+ *	Restart handlers are expected to be registered from non-architecture
+ *	code, typically from drivers. A typical use case would be a system
+ *	where restart functionality is provided through a watchdog. Multiple
+ *	restart handlers may exist; for example, one restart handler might
+ *	restart the entire system, while another only restarts the CPU.
+ *	In such cases, the restart handler which only restarts part of the
+ *	hardware is expected to register with low priority to ensure that
+ *	it only runs if no other means to restart the system is available.
+ *
+ *	Currently always returns zero, as atomic_notifier_chain_register()
+ *	always returns zero.
+ */
+int register_restart_handler(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(register_restart_handler);
+
+/**
+ *	unregister_restart_handler - Unregister previously registered
+ *				     restart handler
+ *	@nb: Hook to be unregistered
+ *
+ *	Unregisters a previously registered restart handler function.
+ *
+ *	Returns zero on success, or %-ENOENT on failure.
+ */
+int unregister_restart_handler(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(unregister_restart_handler);
+
+/**
+ *	do_kernel_restart - Execute kernel restart handler call chain
+ *
+ *	Calls functions registered with register_restart_handler.
+ *
+ *	Expected to be called from machine_restart as last step of the restart
+ *	sequence.
+ *
+ *	Restarts the system immediately if a restart handler function has been
+ *	registered. Otherwise does nothing.
+ */
+void do_kernel_restart(char *cmd)
+{
+	atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
+}
+
 void migrate_to_reboot_cpu(void)
 {
 	/* The boot cpu is always logical cpu 0 */
-- 
1.9.1

[PATCH v6 1/7] kernel: Add support for kernel restart handler call chain

[Guenter Roeck]

Various drivers implement architecture and/or device specific means
to restart (reset) the system. Various mechanisms have been implemented
to support those schemes. The best known mechanism is arm_pm_restart,
which is a function pointer to be set either from platform specific code
or from drivers. Another mechanism is to use hardware watchdogs to issue
a reset; this mechanism is used if there is no other method available
to reset a board or system. Two examples are alim7101_wdt, which currently
uses the reboot notifier to trigger a reset, and moxart_wdt, which registers
the arm_pm_restart function.

The existing mechanisms have a number of drawbacks. Typically only one scheme
to restart the system is supported (at least if arm_pm_restart is used).
At least in theory there can be multiple means to restart the system, some of
which may be less desirable (for example one mechanism may only reset the CPU,
while another may reset the entire system). Using arm_pm_restart can also be
racy if the function pointer is set from a driver, as the driver may be in
the process of being unloaded when arm_pm_restart is called.
Using the reboot notifier is always racy, as it is unknown if and when
other functions using the reboot notifier have completed execution
by the time the watchdog fires.

Introduce a system restart handler call chain to solve the described problems.
This call chain is expected to be executed from the architecture specific
machine_restart() function. Drivers providing system restart functionality
(such as the watchdog drivers mentioned above) are expected to register
with this call chain. By using the priority field in the notifier block,
callers can control restart handler execution sequence and thus ensure that
the restart handler with the optimal restart capabilities for a given system
is called first.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: Use atomic notifier call chain
v5: Function renames:
    register_restart_notifier -> register_restart_handler
    unregister_restart_notifier -> unregister_restart_handler
    kernel_restart_notify -> do_kernel_restart
v4: Document and suggest values for notifier priorities
v3: Add kernel_restart_notify wrapper function to execute notifier.
    Improve documentation.
    Move restart_notifier_list into kernel/reboot.c and make it static.
v2: No change.

 include/linux/reboot.h |  3 ++
 kernel/reboot.c        | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 48bf152..67fc8fc 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -38,6 +38,9 @@ extern int reboot_force;
 extern int register_reboot_notifier(struct notifier_block *);
 extern int unregister_reboot_notifier(struct notifier_block *);
 
+extern int register_restart_handler(struct notifier_block *);
+extern int unregister_restart_handler(struct notifier_block *);
+extern void do_kernel_restart(char *cmd);
 
 /*
  * Architecture-specific implementations of sys_reboot commands.
diff --git a/kernel/reboot.c b/kernel/reboot.c
index a3a9e24..5925f5a 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -104,6 +104,87 @@ int unregister_reboot_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	to restart the system.
+ */
+static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
+
+/**
+ *	register_restart_handler - Register function to be called to reset
+ *				   the system
+ *	@nb: Info about handler function to be called
+ *	@nb->priority:	Handler priority. Handlers should follow the
+ *			following guidelines for setting priorities.
+ *			0:	Restart handler of last resort,
+ *				with limited restart capabilities
+ *			128:	Default restart handler; use if no other
+ *				restart handler is expected to be available,
+ *				and/or if restart functionality is
+ *				sufficient to restart the entire system
+ *			255:	Highest priority restart handler, will
+ *				preempt all other restart handlers
+ *
+ *	Registers a function with code to be called to restart the
+ *	system.
+ *
+ *	Registered functions will be called from machine_restart as last
+ *	step of the restart sequence (if the architecture specific
+ *	machine_restart function calls do_kernel_restart - see below
+ *	for details).
+ *	Registered functions are expected to restart the system immediately.
+ *	If more than one function is registered, the restart handler priority
+ *	selects which function will be called first.
+ *
+ *	Restart handlers are expected to be registered from non-architecture
+ *	code, typically from drivers. A typical use case would be a system
+ *	where restart functionality is provided through a watchdog. Multiple
+ *	restart handlers may exist; for example, one restart handler might
+ *	restart the entire system, while another only restarts the CPU.
+ *	In such cases, the restart handler which only restarts part of the
+ *	hardware is expected to register with low priority to ensure that
+ *	it only runs if no other means to restart the system is available.
+ *
+ *	Currently always returns zero, as atomic_notifier_chain_register()
+ *	always returns zero.
+ */
+int register_restart_handler(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(register_restart_handler);
+
+/**
+ *	unregister_restart_handler - Unregister previously registered
+ *				     restart handler
+ *	@nb: Hook to be unregistered
+ *
+ *	Unregisters a previously registered restart handler function.
+ *
+ *	Returns zero on success, or %-ENOENT on failure.
+ */
+int unregister_restart_handler(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(unregister_restart_handler);
+
+/**
+ *	do_kernel_restart - Execute kernel restart handler call chain
+ *
+ *	Calls functions registered with register_restart_handler.
+ *
+ *	Expected to be called from machine_restart as last step of the restart
+ *	sequence.
+ *
+ *	Restarts the system immediately if a restart handler function has been
+ *	registered. Otherwise does nothing.
+ */
+void do_kernel_restart(char *cmd)
+{
+	atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
+}
+
 void migrate_to_reboot_cpu(void)
 {
 	/* The boot cpu is always logical cpu 0 */
-- 
1.9.1

[PATCH v6 2/7] arm64: Support restart through restart handler call chain

[Guenter Roeck]

The kernel core now supports a restart handler call chain to restart
the system. Call it if arm_pm_restart is not set.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Renamed restart function to do_kernel_restart
v4: No change.
v3: Use wrapper function to execute notifier call chain.
v2: Only call notifier call chain if arm_pm_restart is not set.
    Do not include linux/watchdog.h.

 arch/arm64/kernel/process.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 43b7c34..9591e60 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -174,6 +174,8 @@ void machine_restart(char *cmd)
 	/* Now call the architecture specific reboot code. */
 	if (arm_pm_restart)
 		arm_pm_restart(reboot_mode, cmd);
+	else
+		do_kernel_restart(cmd);
 
 	/*
 	 * Whoops - the architecture was unable to reboot.
-- 
1.9.1

[PATCH v6 2/7] arm64: Support restart through restart handler call chain

[Guenter Roeck]

The kernel core now supports a restart handler call chain to restart
the system. Call it if arm_pm_restart is not set.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Renamed restart function to do_kernel_restart
v4: No change.
v3: Use wrapper function to execute notifier call chain.
v2: Only call notifier call chain if arm_pm_restart is not set.
    Do not include linux/watchdog.h.

 arch/arm64/kernel/process.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 43b7c34..9591e60 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -174,6 +174,8 @@ void machine_restart(char *cmd)
 	/* Now call the architecture specific reboot code. */
 	if (arm_pm_restart)
 		arm_pm_restart(reboot_mode, cmd);
+	else
+		do_kernel_restart(cmd);
 
 	/*
 	 * Whoops - the architecture was unable to reboot.
-- 
1.9.1

[PATCH v6 3/7] arm: Support restart through restart handler call chain

[Guenter Roeck]

The kernel core now supports a restart handler call chain for system
restart functions.

With this change, the arm_pm_restart callback is now optional, so check
if it is set before calling it. Only call the kernel restart handler
if arm_pm_restart is not set.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Renamed restart function to do_kernel_restart
v4: No change.
v3: Use wrapper function to execute notifier call chain.
v2: Only call notifier call chain if arm_pm_restart is not set.
    Do not include linux/watchdog.h.

 arch/arm/kernel/process.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 81ef686..84ca0d5 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -230,7 +230,10 @@ void machine_restart(char *cmd)
 	local_irq_disable();
 	smp_send_stop();
 
-	arm_pm_restart(reboot_mode, cmd);
+	if (arm_pm_restart)
+		arm_pm_restart(reboot_mode, cmd);
+	else
+		do_kernel_restart(cmd);
 
 	/* Give a grace period for failure to restart of 1s */
 	mdelay(1000);
-- 
1.9.1

[PATCH v6 3/7] arm: Support restart through restart handler call chain

[Guenter Roeck]

The kernel core now supports a restart handler call chain for system
restart functions.

With this change, the arm_pm_restart callback is now optional, so check
if it is set before calling it. Only call the kernel restart handler
if arm_pm_restart is not set.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Renamed restart function to do_kernel_restart
v4: No change.
v3: Use wrapper function to execute notifier call chain.
v2: Only call notifier call chain if arm_pm_restart is not set.
    Do not include linux/watchdog.h.

 arch/arm/kernel/process.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 81ef686..84ca0d5 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -230,7 +230,10 @@ void machine_restart(char *cmd)
 	local_irq_disable();
 	smp_send_stop();
 
-	arm_pm_restart(reboot_mode, cmd);
+	if (arm_pm_restart)
+		arm_pm_restart(reboot_mode, cmd);
+	else
+		do_kernel_restart(cmd);
 
 	/* Give a grace period for failure to restart of 1s */
 	mdelay(1000);
-- 
1.9.1

[PATCH v6 4/7] power/restart: Call machine_restart instead of arm_pm_restart

[Guenter Roeck]

machine_restart is supported on non-ARM platforms, and and ultimately calls
arm_pm_restart, so dont call arm_pm_restart directly but use the more
generic function.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: No change.
v4: No change.
v3: No change.
v2: Added patch.

 drivers/power/reset/restart-poweroff.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/power/reset/restart-poweroff.c b/drivers/power/reset/restart-poweroff.c
index 5758033..47f10eb 100644
--- a/drivers/power/reset/restart-poweroff.c
+++ b/drivers/power/reset/restart-poweroff.c
@@ -20,7 +20,8 @@
 
 static void restart_poweroff_do_poweroff(void)
 {
-	arm_pm_restart(REBOOT_HARD, NULL);
+	reboot_mode = REBOOT_HARD;
+	machine_restart(NULL);
 }
 
 static int restart_poweroff_probe(struct platform_device *pdev)
-- 
1.9.1

[PATCH v6 4/7] power/restart: Call machine_restart instead of arm_pm_restart

[Guenter Roeck]

machine_restart is supported on non-ARM platforms, and and ultimately calls
arm_pm_restart, so dont call arm_pm_restart directly but use the more
generic function.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: No change.
v4: No change.
v3: No change.
v2: Added patch.

 drivers/power/reset/restart-poweroff.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/power/reset/restart-poweroff.c b/drivers/power/reset/restart-poweroff.c
index 5758033..47f10eb 100644
--- a/drivers/power/reset/restart-poweroff.c
+++ b/drivers/power/reset/restart-poweroff.c
@@ -20,7 +20,8 @@
 
 static void restart_poweroff_do_poweroff(void)
 {
-	arm_pm_restart(REBOOT_HARD, NULL);
+	reboot_mode = REBOOT_HARD;
+	machine_restart(NULL);
 }
 
 static int restart_poweroff_probe(struct platform_device *pdev)
-- 
1.9.1

[PATCH v6 5/7] watchdog: moxart: Register restart handler with kernel restart handler

[Guenter Roeck]

The kernel now provides an API to trigger a system restart.
Register with it instead of setting arm_pm_restart.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Functions and variables renamed: *notifier -> *handler
v4: Set notifier priority to 128.
v3: Move struct notifier_block into struct moxart_wdt_dev.
    Drop static variable previously needed to access struct moxart_wdt_dev
    from notifier function; use container_of instead.
v2: No change.

 drivers/watchdog/moxart_wdt.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/watchdog/moxart_wdt.c b/drivers/watchdog/moxart_wdt.c
index 4aa3a8a..a64405b 100644
--- a/drivers/watchdog/moxart_wdt.c
+++ b/drivers/watchdog/moxart_wdt.c
@@ -15,12 +15,12 @@
 #include <linux/module.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
+#include <linux/notifier.h>
 #include <linux/platform_device.h>
+#include <linux/reboot.h>
 #include <linux/watchdog.h>
 #include <linux/moduleparam.h>
 
-#include <asm/system_misc.h>
-
 #define REG_COUNT			0x4
 #define REG_MODE			0x8
 #define REG_ENABLE			0xC
@@ -29,17 +29,22 @@ struct moxart_wdt_dev {
 	struct watchdog_device dev;
 	void __iomem *base;
 	unsigned int clock_frequency;
+	struct notifier_block restart_handler;
 };
 
-static struct moxart_wdt_dev *moxart_restart_ctx;
-
 static int heartbeat;
 
-static void moxart_wdt_restart(enum reboot_mode reboot_mode, const char *cmd)
+static int moxart_restart_handle(struct notifier_block *this,
+				 unsigned long mode, void *cmd)
 {
-	writel(1, moxart_restart_ctx->base + REG_COUNT);
-	writel(0x5ab9, moxart_restart_ctx->base + REG_MODE);
-	writel(0x03, moxart_restart_ctx->base + REG_ENABLE);
+	struct moxart_wdt_dev *moxart_wdt = container_of(this,
+							 struct moxart_wdt_dev,
+							 restart_handler);
+	writel(1, moxart_wdt->base + REG_COUNT);
+	writel(0x5ab9, moxart_wdt->base + REG_MODE);
+	writel(0x03, moxart_wdt->base + REG_ENABLE);
+
+	return NOTIFY_DONE;
 }
 
 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
@@ -136,8 +141,12 @@ static int moxart_wdt_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	moxart_restart_ctx = moxart_wdt;
-	arm_pm_restart = moxart_wdt_restart;
+	moxart_wdt->restart_handler.notifier_call = moxart_restart_handle;
+	moxart_wdt->restart_handler.priority = 128;
+	err = register_restart_handler(&moxart_wdt->restart_handler);
+	if (err)
+		dev_err(dev, "cannot register restart notifier (err=%d)\n",
+			err);
 
 	dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 		moxart_wdt->dev.timeout, nowayout);
@@ -149,9 +158,8 @@ static int moxart_wdt_remove(struct platform_device *pdev)
 {
 	struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 
-	arm_pm_restart = NULL;
+	unregister_restart_handler(&moxart_wdt->restart_handler);
 	moxart_wdt_stop(&moxart_wdt->dev);
-	watchdog_unregister_device(&moxart_wdt->dev);
 
 	return 0;
 }
-- 
1.9.1

[PATCH v6 5/7] watchdog: moxart: Register restart handler with kernel restart handler

[Guenter Roeck]

The kernel now provides an API to trigger a system restart.
Register with it instead of setting arm_pm_restart.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Functions and variables renamed: *notifier -> *handler
v4: Set notifier priority to 128.
v3: Move struct notifier_block into struct moxart_wdt_dev.
    Drop static variable previously needed to access struct moxart_wdt_dev
    from notifier function; use container_of instead.
v2: No change.

 drivers/watchdog/moxart_wdt.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/watchdog/moxart_wdt.c b/drivers/watchdog/moxart_wdt.c
index 4aa3a8a..a64405b 100644
--- a/drivers/watchdog/moxart_wdt.c
+++ b/drivers/watchdog/moxart_wdt.c
@@ -15,12 +15,12 @@
 #include <linux/module.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
+#include <linux/notifier.h>
 #include <linux/platform_device.h>
+#include <linux/reboot.h>
 #include <linux/watchdog.h>
 #include <linux/moduleparam.h>
 
-#include <asm/system_misc.h>
-
 #define REG_COUNT			0x4
 #define REG_MODE			0x8
 #define REG_ENABLE			0xC
@@ -29,17 +29,22 @@ struct moxart_wdt_dev {
 	struct watchdog_device dev;
 	void __iomem *base;
 	unsigned int clock_frequency;
+	struct notifier_block restart_handler;
 };
 
-static struct moxart_wdt_dev *moxart_restart_ctx;
-
 static int heartbeat;
 
-static void moxart_wdt_restart(enum reboot_mode reboot_mode, const char *cmd)
+static int moxart_restart_handle(struct notifier_block *this,
+				 unsigned long mode, void *cmd)
 {
-	writel(1, moxart_restart_ctx->base + REG_COUNT);
-	writel(0x5ab9, moxart_restart_ctx->base + REG_MODE);
-	writel(0x03, moxart_restart_ctx->base + REG_ENABLE);
+	struct moxart_wdt_dev *moxart_wdt = container_of(this,
+							 struct moxart_wdt_dev,
+							 restart_handler);
+	writel(1, moxart_wdt->base + REG_COUNT);
+	writel(0x5ab9, moxart_wdt->base + REG_MODE);
+	writel(0x03, moxart_wdt->base + REG_ENABLE);
+
+	return NOTIFY_DONE;
 }
 
 static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
@@ -136,8 +141,12 @@ static int moxart_wdt_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	moxart_restart_ctx = moxart_wdt;
-	arm_pm_restart = moxart_wdt_restart;
+	moxart_wdt->restart_handler.notifier_call = moxart_restart_handle;
+	moxart_wdt->restart_handler.priority = 128;
+	err = register_restart_handler(&moxart_wdt->restart_handler);
+	if (err)
+		dev_err(dev, "cannot register restart notifier (err=%d)\n",
+			err);
 
 	dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
 		moxart_wdt->dev.timeout, nowayout);
@@ -149,9 +158,8 @@ static int moxart_wdt_remove(struct platform_device *pdev)
 {
 	struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
 
-	arm_pm_restart = NULL;
+	unregister_restart_handler(&moxart_wdt->restart_handler);
 	moxart_wdt_stop(&moxart_wdt->dev);
-	watchdog_unregister_device(&moxart_wdt->dev);
 
 	return 0;
 }
-- 
1.9.1

[PATCH v6 6/7] watchdog: alim7101: Register restart handler with kernel restart handler

[Guenter Roeck]

The kernel core now provides an API to trigger a system restart.
Register with it to restart the system instead of misusing the
reboot notifier.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Function and variable renames: *notifier -> *handler.
v4: Set restart notifier priority to 128.
v3: No change.
v2: No change.

 drivers/watchdog/alim7101_wdt.c | 42 +++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/watchdog/alim7101_wdt.c b/drivers/watchdog/alim7101_wdt.c
index 996b2f7..665e0e7 100644
--- a/drivers/watchdog/alim7101_wdt.c
+++ b/drivers/watchdog/alim7101_wdt.c
@@ -301,6 +301,28 @@ static struct miscdevice wdt_miscdev = {
 	.fops	=	&wdt_fops,
 };
 
+static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
+			      void *cmd)
+{
+	/*
+	 * Cobalt devices have no way of rebooting themselves other
+	 * than getting the watchdog to pull reset, so we restart the
+	 * watchdog on reboot with no heartbeat.
+	 */
+	wdt_change(WDT_ENABLE);
+
+	/* loop until the watchdog fires */
+	while (true)
+		;
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block wdt_restart_handler = {
+	.notifier_call = wdt_restart_handle,
+	.priority = 128,
+};
+
 /*
  *	Notifier for system down
  */
@@ -311,15 +333,6 @@ static int wdt_notify_sys(struct notifier_block *this,
 	if (code == SYS_DOWN || code == SYS_HALT)
 		wdt_turnoff();
 
-	if (code == SYS_RESTART) {
-		/*
-		 * Cobalt devices have no way of rebooting themselves other
-		 * than getting the watchdog to pull reset, so we restart the
-		 * watchdog on reboot with no heartbeat
-		 */
-		wdt_change(WDT_ENABLE);
-		pr_info("Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second\n");
-	}
 	return NOTIFY_DONE;
 }
 
@@ -338,6 +351,7 @@ static void __exit alim7101_wdt_unload(void)
 	/* Deregister */
 	misc_deregister(&wdt_miscdev);
 	unregister_reboot_notifier(&wdt_notifier);
+	unregister_restart_handler(&wdt_restart_handler);
 	pci_dev_put(alim7101_pmu);
 }
 
@@ -390,11 +404,17 @@ static int __init alim7101_wdt_init(void)
 		goto err_out;
 	}
 
+	rc = register_restart_handler(&wdt_restart_handler);
+	if (rc) {
+		pr_err("cannot register restart handler (err=%d)\n", rc);
+		goto err_out_reboot;
+	}
+
 	rc = misc_register(&wdt_miscdev);
 	if (rc) {
 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 		       wdt_miscdev.minor, rc);
-		goto err_out_reboot;
+		goto err_out_restart;
 	}
 
 	if (nowayout)
@@ -404,6 +424,8 @@ static int __init alim7101_wdt_init(void)
 		timeout, nowayout);
 	return 0;
 
+err_out_restart:
+	unregister_restart_handler(&wdt_restart_handler);
 err_out_reboot:
 	unregister_reboot_notifier(&wdt_notifier);
 err_out:
-- 
1.9.1

[PATCH v6 6/7] watchdog: alim7101: Register restart handler with kernel restart handler

[Guenter Roeck]

The kernel core now provides an API to trigger a system restart.
Register with it to restart the system instead of misusing the
reboot notifier.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change.
v5: Function and variable renames: *notifier -> *handler.
v4: Set restart notifier priority to 128.
v3: No change.
v2: No change.

 drivers/watchdog/alim7101_wdt.c | 42 +++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/watchdog/alim7101_wdt.c b/drivers/watchdog/alim7101_wdt.c
index 996b2f7..665e0e7 100644
--- a/drivers/watchdog/alim7101_wdt.c
+++ b/drivers/watchdog/alim7101_wdt.c
@@ -301,6 +301,28 @@ static struct miscdevice wdt_miscdev = {
 	.fops	=	&wdt_fops,
 };
 
+static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
+			      void *cmd)
+{
+	/*
+	 * Cobalt devices have no way of rebooting themselves other
+	 * than getting the watchdog to pull reset, so we restart the
+	 * watchdog on reboot with no heartbeat.
+	 */
+	wdt_change(WDT_ENABLE);
+
+	/* loop until the watchdog fires */
+	while (true)
+		;
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block wdt_restart_handler = {
+	.notifier_call = wdt_restart_handle,
+	.priority = 128,
+};
+
 /*
  *	Notifier for system down
  */
@@ -311,15 +333,6 @@ static int wdt_notify_sys(struct notifier_block *this,
 	if (code == SYS_DOWN || code == SYS_HALT)
 		wdt_turnoff();
 
-	if (code == SYS_RESTART) {
-		/*
-		 * Cobalt devices have no way of rebooting themselves other
-		 * than getting the watchdog to pull reset, so we restart the
-		 * watchdog on reboot with no heartbeat
-		 */
-		wdt_change(WDT_ENABLE);
-		pr_info("Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second\n");
-	}
 	return NOTIFY_DONE;
 }
 
@@ -338,6 +351,7 @@ static void __exit alim7101_wdt_unload(void)
 	/* Deregister */
 	misc_deregister(&wdt_miscdev);
 	unregister_reboot_notifier(&wdt_notifier);
+	unregister_restart_handler(&wdt_restart_handler);
 	pci_dev_put(alim7101_pmu);
 }
 
@@ -390,11 +404,17 @@ static int __init alim7101_wdt_init(void)
 		goto err_out;
 	}
 
+	rc = register_restart_handler(&wdt_restart_handler);
+	if (rc) {
+		pr_err("cannot register restart handler (err=%d)\n", rc);
+		goto err_out_reboot;
+	}
+
 	rc = misc_register(&wdt_miscdev);
 	if (rc) {
 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 		       wdt_miscdev.minor, rc);
-		goto err_out_reboot;
+		goto err_out_restart;
 	}
 
 	if (nowayout)
@@ -404,6 +424,8 @@ static int __init alim7101_wdt_init(void)
 		timeout, nowayout);
 	return 0;
 
+err_out_restart:
+	unregister_restart_handler(&wdt_restart_handler);
 err_out_reboot:
 	unregister_reboot_notifier(&wdt_notifier);
 err_out:
-- 
1.9.1

[PATCH v6 7/7] arm/arm64: Unexport restart handlers

[Guenter Roeck]

Implementing a restart handler in a module don't make sense
as there would be no guarantee that the module is loaded when
a restart is needed. Unexport arm_pm_restart to ensure that
no one gets the idea to do it anyway.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change
v5: No change
v4: No change
v3: No change
v2: No change

 arch/arm/kernel/process.c   | 1 -
 arch/arm64/kernel/process.c | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 84ca0d5..27bdf11 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -125,7 +125,6 @@ void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
 
 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;
-EXPORT_SYMBOL_GPL(arm_pm_restart);
 
 /*
  * This is our default idle handler.
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 9591e60..f5fddff 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -92,7 +92,6 @@ void (*pm_power_off)(void);
 EXPORT_SYMBOL_GPL(pm_power_off);
 
 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
-EXPORT_SYMBOL_GPL(arm_pm_restart);
 
 /*
  * This is our default idle handler.
-- 
1.9.1

[PATCH v6 7/7] arm/arm64: Unexport restart handlers

[Guenter Roeck]

Implementing a restart handler in a module don't make sense
as there would be no guarantee that the module is loaded when
a restart is needed. Unexport arm_pm_restart to ensure that
no one gets the idea to do it anyway.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v6: No change
v5: No change
v4: No change
v3: No change
v2: No change

 arch/arm/kernel/process.c   | 1 -
 arch/arm64/kernel/process.c | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 84ca0d5..27bdf11 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -125,7 +125,6 @@ void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
 
 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;
-EXPORT_SYMBOL_GPL(arm_pm_restart);
 
 /*
  * This is our default idle handler.
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 9591e60..f5fddff 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -92,7 +92,6 @@ void (*pm_power_off)(void);
 EXPORT_SYMBOL_GPL(pm_power_off);
 
 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
-EXPORT_SYMBOL_GPL(arm_pm_restart);
 
 /*
  * This is our default idle handler.
-- 
1.9.1

Re: [PATCH v6 3/7] arm: Support restart through restart handler call chain

[Heiko Stübner]

Hi Guenter,

Am Montag, 4. August 2014, 18:48:54 schrieb Guenter Roeck:
> The kernel core now supports a restart handler call chain for system
> restart functions.
> 
> With this change, the arm_pm_restart callback is now optional, so check
> if it is set before calling it. Only call the kernel restart handler
> if arm_pm_restart is not set.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Acked-by: Heiko Stuebner <heiko@sntech.de>
> ---
> v6: No change.
> v5: Renamed restart function to do_kernel_restart
> v4: No change.
> v3: Use wrapper function to execute notifier call chain.
> v2: Only call notifier call chain if arm_pm_restart is not set.
>     Do not include linux/watchdog.h.
> 
>  arch/arm/kernel/process.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index 81ef686..84ca0d5 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -230,7 +230,10 @@ void machine_restart(char *cmd)
>  	local_irq_disable();
>  	smp_send_stop();
> 
> -	arm_pm_restart(reboot_mode, cmd);
> +	if (arm_pm_restart)
> +		arm_pm_restart(reboot_mode, cmd);
> +	else
> +		do_kernel_restart(cmd);
> 
>  	/* Give a grace period for failure to restart of 1s */
>  	mdelay(1000);

shouldn't you also get rid of 

	void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;

like a previous attempt at unifying the restart handling [0] did.

Because when testing the current series on my Rockchip boards, there was
always an arm_pm_restart defined ... namely the null_restart mentioned above.
So do_kernel_restart is never reached until I disable the null_restart.


Heiko


[0] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/277042

[PATCH v6 3/7] arm: Support restart through restart handler call chain

[Heiko Stübner]

Hi Guenter,

Am Montag, 4. August 2014, 18:48:54 schrieb Guenter Roeck:
> The kernel core now supports a restart handler call chain for system
> restart functions.
> 
> With this change, the arm_pm_restart callback is now optional, so check
> if it is set before calling it. Only call the kernel restart handler
> if arm_pm_restart is not set.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Acked-by: Heiko Stuebner <heiko@sntech.de>
> ---
> v6: No change.
> v5: Renamed restart function to do_kernel_restart
> v4: No change.
> v3: Use wrapper function to execute notifier call chain.
> v2: Only call notifier call chain if arm_pm_restart is not set.
>     Do not include linux/watchdog.h.
> 
>  arch/arm/kernel/process.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index 81ef686..84ca0d5 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -230,7 +230,10 @@ void machine_restart(char *cmd)
>  	local_irq_disable();
>  	smp_send_stop();
> 
> -	arm_pm_restart(reboot_mode, cmd);
> +	if (arm_pm_restart)
> +		arm_pm_restart(reboot_mode, cmd);
> +	else
> +		do_kernel_restart(cmd);
> 
>  	/* Give a grace period for failure to restart of 1s */
>  	mdelay(1000);

shouldn't you also get rid of 

	void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;

like a previous attempt at unifying the restart handling [0] did.

Because when testing the current series on my Rockchip boards, there was
always an arm_pm_restart defined ... namely the null_restart mentioned above.
So do_kernel_restart is never reached until I disable the null_restart.


Heiko


[0] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/277042

[PATCH v2] clk: rockchip: add restart handler

[Heiko Stübner]

Add infrastructure to write the correct value to the restart register and
register the restart notifier for both rk3188 (including rk3066) and rk3288.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
This of course needs the restart generalization from Guenter Roeck
and would need to go with that series.

changes since v1:
- adapt to changed restart notifier handling

 drivers/clk/rockchip/clk-rk3188.c |  2 ++
 drivers/clk/rockchip/clk-rk3288.c |  2 ++
 drivers/clk/rockchip/clk.c        | 25 +++++++++++++++++++++++++
 drivers/clk/rockchip/clk.h        |  1 +
 4 files changed, 30 insertions(+)

diff --git a/drivers/clk/rockchip/clk-rk3188.c b/drivers/clk/rockchip/clk-rk3188.c
index a83a6d8..71b661a 100644
--- a/drivers/clk/rockchip/clk-rk3188.c
+++ b/drivers/clk/rockchip/clk-rk3188.c
@@ -631,6 +631,8 @@ static void __init rk3188_common_clk_init(struct device_node *np)
 
 	rockchip_register_softrst(np, 9, reg_base + RK2928_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);
+
+	rockchip_register_restart_notifier(RK2928_GLB_SRST_FST);
 }
 
 static void __init rk3066a_clk_init(struct device_node *np)
diff --git a/drivers/clk/rockchip/clk-rk3288.c b/drivers/clk/rockchip/clk-rk3288.c
index 0d8c6c5..b604217 100644
--- a/drivers/clk/rockchip/clk-rk3288.c
+++ b/drivers/clk/rockchip/clk-rk3288.c
@@ -713,5 +713,7 @@ static void __init rk3288_clk_init(struct device_node *np)
 
 	rockchip_register_softrst(np, 9, reg_base + RK3288_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);
+
+	rockchip_register_restart_notifier(RK3288_GLB_SRST_FST);
 }
 CLK_OF_DECLARE(rk3288_cru, "rockchip,rk3288-cru", rk3288_clk_init);
diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
index 278cf9d..aa41433 100644
--- a/drivers/clk/rockchip/clk.c
+++ b/drivers/clk/rockchip/clk.c
@@ -25,6 +25,7 @@
 #include <linux/clk-provider.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
+#include <linux/reboot.h>
 #include "clk.h"
 
 /**
@@ -242,3 +243,27 @@ void __init rockchip_clk_register_branches(
 		rockchip_clk_add_lookup(clk, list->id);
 	}
 }
+
+static unsigned int reg_restart;
+static int rockchip_restart_notify(struct notifier_block *this,
+				   unsigned long mode, void *cmd)
+{
+	writel(0xfdb9, reg_base + reg_restart);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rockchip_restart_handler = {
+	.notifier_call = rockchip_restart_notify,
+	.priority = 128,
+};
+
+void __init rockchip_register_restart_notifier(unsigned int reg)
+{
+	int ret;
+
+	reg_restart = reg;
+	ret = register_restart_handler(&rockchip_restart_handler);
+	if (ret)
+		pr_err("%s: cannot register restart handler, %d\n",
+		       __func__, ret);
+}
diff --git a/drivers/clk/rockchip/clk.h b/drivers/clk/rockchip/clk.h
index 887cbde..0b5eab5 100644
--- a/drivers/clk/rockchip/clk.h
+++ b/drivers/clk/rockchip/clk.h
@@ -329,6 +329,7 @@ void rockchip_clk_register_branches(struct rockchip_clk_branch *clk_list,
 				    unsigned int nr_clk);
 void rockchip_clk_register_plls(struct rockchip_pll_clock *pll_list,
 				unsigned int nr_pll, int grf_lock_offset);
+void rockchip_register_restart_notifier(unsigned int reg);
 
 #define ROCKCHIP_SOFTRST_HIWORD_MASK	BIT(0)
 
-- 
2.0.1

[PATCH v2] clk: rockchip: add restart handler

[Heiko Stübner]

Add infrastructure to write the correct value to the restart register and
register the restart notifier for both rk3188 (including rk3066) and rk3288.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
This of course needs the restart generalization from Guenter Roeck
and would need to go with that series.

changes since v1:
- adapt to changed restart notifier handling

 drivers/clk/rockchip/clk-rk3188.c |  2 ++
 drivers/clk/rockchip/clk-rk3288.c |  2 ++
 drivers/clk/rockchip/clk.c        | 25 +++++++++++++++++++++++++
 drivers/clk/rockchip/clk.h        |  1 +
 4 files changed, 30 insertions(+)

diff --git a/drivers/clk/rockchip/clk-rk3188.c b/drivers/clk/rockchip/clk-rk3188.c
index a83a6d8..71b661a 100644
--- a/drivers/clk/rockchip/clk-rk3188.c
+++ b/drivers/clk/rockchip/clk-rk3188.c
@@ -631,6 +631,8 @@ static void __init rk3188_common_clk_init(struct device_node *np)
 
 	rockchip_register_softrst(np, 9, reg_base + RK2928_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);
+
+	rockchip_register_restart_notifier(RK2928_GLB_SRST_FST);
 }
 
 static void __init rk3066a_clk_init(struct device_node *np)
diff --git a/drivers/clk/rockchip/clk-rk3288.c b/drivers/clk/rockchip/clk-rk3288.c
index 0d8c6c5..b604217 100644
--- a/drivers/clk/rockchip/clk-rk3288.c
+++ b/drivers/clk/rockchip/clk-rk3288.c
@@ -713,5 +713,7 @@ static void __init rk3288_clk_init(struct device_node *np)
 
 	rockchip_register_softrst(np, 9, reg_base + RK3288_SOFTRST_CON(0),
 				  ROCKCHIP_SOFTRST_HIWORD_MASK);
+
+	rockchip_register_restart_notifier(RK3288_GLB_SRST_FST);
 }
 CLK_OF_DECLARE(rk3288_cru, "rockchip,rk3288-cru", rk3288_clk_init);
diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
index 278cf9d..aa41433 100644
--- a/drivers/clk/rockchip/clk.c
+++ b/drivers/clk/rockchip/clk.c
@@ -25,6 +25,7 @@
 #include <linux/clk-provider.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
+#include <linux/reboot.h>
 #include "clk.h"
 
 /**
@@ -242,3 +243,27 @@ void __init rockchip_clk_register_branches(
 		rockchip_clk_add_lookup(clk, list->id);
 	}
 }
+
+static unsigned int reg_restart;
+static int rockchip_restart_notify(struct notifier_block *this,
+				   unsigned long mode, void *cmd)
+{
+	writel(0xfdb9, reg_base + reg_restart);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rockchip_restart_handler = {
+	.notifier_call = rockchip_restart_notify,
+	.priority = 128,
+};
+
+void __init rockchip_register_restart_notifier(unsigned int reg)
+{
+	int ret;
+
+	reg_restart = reg;
+	ret = register_restart_handler(&rockchip_restart_handler);
+	if (ret)
+		pr_err("%s: cannot register restart handler, %d\n",
+		       __func__, ret);
+}
diff --git a/drivers/clk/rockchip/clk.h b/drivers/clk/rockchip/clk.h
index 887cbde..0b5eab5 100644
--- a/drivers/clk/rockchip/clk.h
+++ b/drivers/clk/rockchip/clk.h
@@ -329,6 +329,7 @@ void rockchip_clk_register_branches(struct rockchip_clk_branch *clk_list,
 				    unsigned int nr_clk);
 void rockchip_clk_register_plls(struct rockchip_pll_clock *pll_list,
 				unsigned int nr_pll, int grf_lock_offset);
+void rockchip_register_restart_notifier(unsigned int reg);
 
 #define ROCKCHIP_SOFTRST_HIWORD_MASK	BIT(0)
 
-- 
2.0.1

Re: [PATCH v6 3/7] arm: Support restart through restart handler call chain

[Guenter Roeck]

On 08/09/2014 01:01 PM, Heiko Stübner wrote:
> Hi Guenter,
>
> Am Montag, 4. August 2014, 18:48:54 schrieb Guenter Roeck:
>> The kernel core now supports a restart handler call chain for system
>> restart functions.
>>
>> With this change, the arm_pm_restart callback is now optional, so check
>> if it is set before calling it. Only call the kernel restart handler
>> if arm_pm_restart is not set.
>>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
>> Acked-by: Heiko Stuebner <heiko@sntech.de>
>> ---
>> v6: No change.
>> v5: Renamed restart function to do_kernel_restart
>> v4: No change.
>> v3: Use wrapper function to execute notifier call chain.
>> v2: Only call notifier call chain if arm_pm_restart is not set.
>>      Do not include linux/watchdog.h.
>>
>>   arch/arm/kernel/process.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
>> index 81ef686..84ca0d5 100644
>> --- a/arch/arm/kernel/process.c
>> +++ b/arch/arm/kernel/process.c
>> @@ -230,7 +230,10 @@ void machine_restart(char *cmd)
>>   	local_irq_disable();
>>   	smp_send_stop();
>>
>> -	arm_pm_restart(reboot_mode, cmd);
>> +	if (arm_pm_restart)
>> +		arm_pm_restart(reboot_mode, cmd);
>> +	else
>> +		do_kernel_restart(cmd);
>>
>>   	/* Give a grace period for failure to restart of 1s */
>>   	mdelay(1000);
>
> shouldn't you also get rid of
>
> 	void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;
>
Yes. Looks like I'll need another revision.

Even worse, the current upstream code is somewhat broken and doesn't really
like the following instructions.
	drivers/watchdog/moxart_wdt.c:  arm_pm_restart = NULL;
	drivers/watchdog/sunxi_wdt.c:   arm_pm_restart = NULL;

Fortunately that code is only executed if those drivers are built as modules
and unloaded.

Guenter

> like a previous attempt at unifying the restart handling [0] did.
>
> Because when testing the current series on my Rockchip boards, there was
> always an arm_pm_restart defined ... namely the null_restart mentioned above.
> So do_kernel_restart is never reached until I disable the null_restart.
>
>
> Heiko
>
>
> [0] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/277042
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>

[PATCH v6 3/7] arm: Support restart through restart handler call chain

[Guenter Roeck]

On 08/09/2014 01:01 PM, Heiko St?bner wrote:
> Hi Guenter,
>
> Am Montag, 4. August 2014, 18:48:54 schrieb Guenter Roeck:
>> The kernel core now supports a restart handler call chain for system
>> restart functions.
>>
>> With this change, the arm_pm_restart callback is now optional, so check
>> if it is set before calling it. Only call the kernel restart handler
>> if arm_pm_restart is not set.
>>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
>> Acked-by: Heiko Stuebner <heiko@sntech.de>
>> ---
>> v6: No change.
>> v5: Renamed restart function to do_kernel_restart
>> v4: No change.
>> v3: Use wrapper function to execute notifier call chain.
>> v2: Only call notifier call chain if arm_pm_restart is not set.
>>      Do not include linux/watchdog.h.
>>
>>   arch/arm/kernel/process.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
>> index 81ef686..84ca0d5 100644
>> --- a/arch/arm/kernel/process.c
>> +++ b/arch/arm/kernel/process.c
>> @@ -230,7 +230,10 @@ void machine_restart(char *cmd)
>>   	local_irq_disable();
>>   	smp_send_stop();
>>
>> -	arm_pm_restart(reboot_mode, cmd);
>> +	if (arm_pm_restart)
>> +		arm_pm_restart(reboot_mode, cmd);
>> +	else
>> +		do_kernel_restart(cmd);
>>
>>   	/* Give a grace period for failure to restart of 1s */
>>   	mdelay(1000);
>
> shouldn't you also get rid of
>
> 	void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;
>
Yes. Looks like I'll need another revision.

Even worse, the current upstream code is somewhat broken and doesn't really
like the following instructions.
	drivers/watchdog/moxart_wdt.c:  arm_pm_restart = NULL;
	drivers/watchdog/sunxi_wdt.c:   arm_pm_restart = NULL;

Fortunately that code is only executed if those drivers are built as modules
and unloaded.

Guenter

> like a previous attempt at unifying the restart handling [0] did.
>
> Because when testing the current series on my Rockchip boards, there was
> always an arm_pm_restart defined ... namely the null_restart mentioned above.
> So do_kernel_restart is never reached until I disable the null_restart.
>
>
> Heiko
>
>
> [0] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/277042
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>