arm: support restart through restart handler call chain

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 drop its
initialization and 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 <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Acked-by: Heiko Stuebner <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Dmitry Eremin-Solenikov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jonas Jensen <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Russell King <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Tomasz Figa <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Wim Van Sebroeck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 5 insertions, 6 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 81ef686a91ca..ea279f7a8767 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -114,17 +114,13 @@ void soft_restart(unsigned long addr)
 	BUG();
 }
 
-static void null_restart(enum reboot_mode reboot_mode, const char *cmd)
-{
-}
-
 /*
  * Function pointers to optional machine specific functions
  */
 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
 
-void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;
+void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
 EXPORT_SYMBOL_GPL(arm_pm_restart);
 
 /*
@@ -230,7 +226,10 @@ 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);