restart: replace reset_cpu with registered restart handlers

This replaces the reset_cpu() function which every SoC or board must
provide with registered handlers. This makes it possible to have multiple
reset functions for boards which have multiple ways to reset the machine.
Also boards which have no way at all to reset the machine no longer
have to provide a dummy reset_cpu() function.

The problem this solves is that some machines have external PMICs or
similar to reset the system which have to be preferred over the
internal SoC reset, because the PMIC can reset not only the SoC but also
the external devices.

To pick the right way to reset a machine each handler has a priority. The
default priority is 100 and all currently existing restart handlers are
registered with this priority. of_get_restart_priority() allows to retrieve
the priority from the device tree which makes it possible for boards to
give certain restart handlers a higher priority in order to use this one
instead of the default one.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

5 files changed, 26 insertions, 8 deletions

diff --git a/arch/arm/mach-at91/at91rm9200_time.c b/arch/arm/mach-at91/at91rm9200_time.c
index ae0172b4f4..fd11223b6f 100644
--- a/arch/arm/mach-at91/at91rm9200_time.c
+++ b/arch/arm/mach-at91/at91rm9200_time.c
@@ -28,6 +28,7 @@
 #include <common.h>
 #include <init.h>
 #include <clock.h>
+#include <restart.h>
 #include <mach/hardware.h>
 #include <mach/at91_tc.h>
 #include <mach/at91_st.h>
@@ -77,7 +78,7 @@ core_initcall(clocksource_init);
 /*
  * Reset the cpu through the reset controller
  */
-void __noreturn reset_cpu (unsigned long ignored)
+static void __noreturn at91rm9200_restart_soc(struct restart_handler *rst)
 {
 	/*
 	 * Perform a hardware reset with the use of the Watchdog timer.
@@ -86,6 +87,13 @@ void __noreturn reset_cpu (unsigned long ignored)
 	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
 
 	/* Not reached */
-	while (1);
+	hang();
 }
-EXPORT_SYMBOL(reset_cpu);
+
+static int restart_register_feature(void)
+{
+	restart_handler_register_fn(at91rm9200_restart_soc);
+
+	return 0;
+}
+coredevice_initcall(restart_register_feature);
diff --git a/arch/arm/mach-at91/at91sam9_reset.S b/arch/arm/mach-at91/at91sam9_reset.S
index 3a3e77aaa5..890545edbf 100644
--- a/arch/arm/mach-at91/at91sam9_reset.S
+++ b/arch/arm/mach-at91/at91sam9_reset.S
@@ -20,9 +20,9 @@
 
 			.arm
 
-			.globl	reset_cpu
+			.globl	restart_sam9
 
-reset_cpu:		ldr	r0, .at91_va_base_sdramc			@ preload constants
+restart_sam9:		ldr	r0, .at91_va_base_sdramc			@ preload constants
 			ldr	r1, .at91_va_base_rstc_cr
 
 			mov	r2, #1
diff --git a/arch/arm/mach-at91/at91sam9g45_reset.S b/arch/arm/mach-at91/at91sam9g45_reset.S
index e70d733ac8..2cb113cdb4 100644
--- a/arch/arm/mach-at91/at91sam9g45_reset.S
+++ b/arch/arm/mach-at91/at91sam9g45_reset.S
@@ -17,9 +17,9 @@
 
 			.arm
 
-			.globl	reset_cpu
+			.globl	restart_sam9g45
 
-reset_cpu:		ldr	r0, .at91_va_base_sdramc	@ preload constants
+restart_sam9g45:	ldr	r0, .at91_va_base_sdramc	@ preload constants
 			ldr	r1, .at91_va_base_rstc_cr
 
 			mov	r2, #1
diff --git a/arch/arm/mach-at91/bootstrap.c b/arch/arm/mach-at91/bootstrap.c
index 2d18dd6b32..1baf7323fe 100644
--- a/arch/arm/mach-at91/bootstrap.c
+++ b/arch/arm/mach-at91/bootstrap.c
@@ -9,6 +9,7 @@
 #include <mach/bootstrap.h>
 #include <linux/sizes.h>
 #include <malloc.h>
+#include <restart.h>
 #include <init.h>
 #include <menu.h>
 
@@ -145,7 +146,7 @@ static void boot_mmc_disk_action(struct menu *m, struct menu_entry *me)
 
 static void boot_reset_action(struct menu *m, struct menu_entry *me)
 {
-	reset_cpu(0);
+	restart_machine();
 }
 
 void at91_bootstrap_menu(void)
diff --git a/arch/arm/mach-at91/setup.c b/arch/arm/mach-at91/setup.c
index 341979ae89..1fa50ac054 100644
--- a/arch/arm/mach-at91/setup.c
+++ b/arch/arm/mach-at91/setup.c
@@ -8,6 +8,7 @@
 #include <common.h>
 #include <io.h>
 #include <init.h>
+#include <restart.h>
 
 #include <mach/hardware.h>
 #include <mach/cpu.h>
@@ -296,6 +297,9 @@ static int at91_detect(void)
 }
 postcore_initcall(at91_detect);
 
+void restart_sam9(struct restart_handler *rst);
+void restart_sam9g45(struct restart_handler *rst);
+
 static int at91_soc_device(void)
 {
 	struct device_d *dev;
@@ -304,6 +308,11 @@ static int at91_soc_device(void)
 	dev_add_param_fixed(dev, "name", (char*)at91_get_soc_type(&at91_soc_initdata));
 	dev_add_param_fixed(dev, "subname", (char*)at91_get_soc_subtype(&at91_soc_initdata));
 
+	if (IS_ENABLED(CONFIG_AT91SAM9_RESET))
+		restart_handler_register_fn(restart_sam9);
+	if (IS_ENABLED(CONFIG_AT91SAM9G45_RESET))
+		restart_handler_register_fn(restart_sam9g45);
+
 	return 0;
 }
 coredevice_initcall(at91_soc_device);