[PATCH v2] pinctrl: qcom: use restart_notifier mechanism for ps_hold

[Josh Cartwright]

By converting to the restart_notifier mechanism for restart, we allow
for other mechanisms, like the watchdog, to be used for restart in the
case where PS_HOLD has failed to reset the chip.

Since this mechanism may be one of several mechanisms registered, change
the post-ps_hold write timeout to be a more reasonable 1 second instead
of 10 seconds.

Choose priority 128, as according to documentation, this mechanism "is
sufficient to restart the entire system".

Cc: Pramod Gurav <pramod.gurav@xxxxxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Tested-by: Pramod Gurav <pramod.gurav@xxxxxxxxxxxxxxx>
Signed-off-by: Josh Cartwright <joshc@xxxxxxxxxxxxxx>
---

Changes since v1:
  - Simplified conditional notifier block registration
  - Reduced wait time to 1s, which I've found to be sufficient on an IFC6410
    board.

 drivers/pinctrl/qcom/pinctrl-msm.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
index d5ed127..d30dddd 100644
--- a/drivers/pinctrl/qcom/pinctrl-msm.c
+++ b/drivers/pinctrl/qcom/pinctrl-msm.c
@@ -27,8 +27,7 @@
 #include <linux/gpio.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
-
-#include <asm/system_misc.h>
+#include <linux/reboot.h>
 
 #include "../core.h"
 #include "../pinconf.h"
@@ -43,6 +42,7 @@
  * @dev:            device handle.
  * @pctrl:          pinctrl handle.
  * @chip:           gpiochip handle.
+ * @restart_nb:     restart notifier block.
  * @irq:            parent irq for the TLMM irq_chip.
  * @lock:           Spinlock to protect register resources as well
  *                  as msm_pinctrl data structures.
@@ -56,6 +56,7 @@ struct msm_pinctrl {
 	struct device *dev;
 	struct pinctrl_dev *pctrl;
 	struct gpio_chip chip;
+	struct notifier_block restart_nb;
 	int irq;
 
 	spinlock_t lock;
@@ -852,13 +853,14 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
 	return 0;
 }
 
-#ifdef CONFIG_ARM
-static void __iomem *msm_ps_hold;
-
-static void msm_reset(enum reboot_mode reboot_mode, const char *cmd)
+static int msm_ps_hold_restart(struct notifier_block *nb, unsigned long action,
+			       void *data)
 {
-	writel(0, msm_ps_hold);
-	mdelay(10000);
+	struct msm_pinctrl *pctrl = container_of(nb, struct msm_pinctrl, restart_nb);
+
+	writel(0, pctrl->regs + PS_HOLD_OFFSET);
+	mdelay(1000);
+	return NOTIFY_DONE;
 }
 
 static void msm_pinctrl_setup_pm_reset(struct msm_pinctrl *pctrl)
@@ -868,13 +870,14 @@ static void msm_pinctrl_setup_pm_reset(struct msm_pinctrl *pctrl)
 
 	for (; i <= pctrl->soc->nfunctions; i++)
 		if (!strcmp(func[i].name, "ps_hold")) {
-			msm_ps_hold = pctrl->regs + PS_HOLD_OFFSET;
-			arm_pm_restart = msm_reset;
+			pctrl->restart_nb.notifier_call = msm_ps_hold_restart;
+			pctrl->restart_nb.priority = 128;
+			if (register_restart_handler(&pctrl->restart_nb))
+				dev_err(pctrl->dev,
+					"failed to setup restart handler.\n");
+			break;
 		}
 }
-#else
-static void msm_pinctrl_setup_pm_reset(const struct msm_pinctrl *pctrl) {}
-#endif
 
 int msm_pinctrl_probe(struct platform_device *pdev,
 		      const struct msm_pinctrl_soc_data *soc_data)
@@ -943,6 +946,8 @@ int msm_pinctrl_remove(struct platform_device *pdev)
 
 	pinctrl_unregister(pctrl->pctrl);
 
+	unregister_restart_handler(&pctrl->restart_nb);
+
 	return 0;
 }
 EXPORT_SYMBOL(msm_pinctrl_remove);
-- 
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