ARM: bcm2835: Move the restart/power_off handling to the WDT driver

Since the WDT is what's used to drive restart and power off, it makes
more sense to keep it there, where the regs are already mapped and
definitions for them provided.  Note that this means you may need to
add CONFIG_BCM2835_WDT to retain functionality of your kernel.

Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
index 2b5a9bbf80b7..7116968dee12 100644
--- a/drivers/watchdog/bcm2835_wdt.c
+++ b/drivers/watchdog/bcm2835_wdt.c
@@ -13,20 +13,25 @@
  * option) any later version.
  */
 
+#include <linux/delay.h>
+#include <linux/reboot.h>
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/watchdog.h>
 #include <linux/platform_device.h>
 #include <linux/of_address.h>
+#include <linux/of_platform.h>
 
 #define PM_RSTC				0x1c
+#define PM_RSTS				0x20
 #define PM_WDOG				0x24
 
 #define PM_PASSWORD			0x5a000000
 
 #define PM_WDOG_TIME_SET		0x000fffff
 #define PM_RSTC_WRCFG_CLR		0xffffffcf
+#define PM_RSTS_HADWRH_SET		0x00000040
 #define PM_RSTC_WRCFG_SET		0x00000030
 #define PM_RSTC_WRCFG_FULL_RESET	0x00000020
 #define PM_RSTC_RESET			0x00000102
@@ -37,6 +42,7 @@
 struct bcm2835_wdt {
 	void __iomem		*base;
 	spinlock_t		lock;
+	struct notifier_block	restart_handler;
 };
 
 static unsigned int heartbeat;
@@ -106,6 +112,53 @@ static struct watchdog_device bcm2835_wdt_wdd = {
 	.timeout =	WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 };
 
+static int
+bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
+{
+	struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
+					       restart_handler);
+	u32 val;
+
+	/* use a timeout of 10 ticks (~150us) */
+	writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
+	val = readl_relaxed(wdt->base + PM_RSTC);
+	val &= PM_RSTC_WRCFG_CLR;
+	val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
+	writel_relaxed(val, wdt->base + PM_RSTC);
+
+	/* No sleeping, possibly atomic. */
+	mdelay(1);
+
+	return 0;
+}
+
+/*
+ * We can't really power off, but if we do the normal reset scheme, and
+ * indicate to bootcode.bin not to reboot, then most of the chip will be
+ * powered off.
+ */
+static void bcm2835_power_off(void)
+{
+	struct device_node *np =
+		of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
+	struct platform_device *pdev = of_find_device_by_node(np);
+	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
+	u32 val;
+
+	/*
+	 * We set the watchdog hard reset bit here to distinguish this reset
+	 * from the normal (full) reset. bootcode.bin will not reboot after a
+	 * hard reset.
+	 */
+	val = readl_relaxed(wdt->base + PM_RSTS);
+	val &= PM_RSTC_WRCFG_CLR;
+	val |= PM_PASSWORD | PM_RSTS_HADWRH_SET;
+	writel_relaxed(val, wdt->base + PM_RSTS);
+
+	/* Continue with normal reset mechanism */
+	bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
+}
+
 static int bcm2835_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -136,6 +189,12 @@ static int bcm2835_wdt_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	wdt->restart_handler.notifier_call = bcm2835_restart;
+	wdt->restart_handler.priority = 128;
+	register_restart_handler(&wdt->restart_handler);
+	if (pm_power_off == NULL)
+		pm_power_off = bcm2835_power_off;
+
 	dev_info(dev, "Broadcom BCM2835 watchdog timer");
 	return 0;
 }
@@ -144,6 +203,9 @@ static int bcm2835_wdt_remove(struct platform_device *pdev)
 {
 	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 
+	unregister_restart_handler(&wdt->restart_handler);
+	if (pm_power_off == bcm2835_power_off)
+		pm_power_off = NULL;
 	watchdog_unregister_device(&bcm2835_wdt_wdd);
 	iounmap(wdt->base);