[PATCH v2 1/2] power: reset: gpio-poweroff: add force mode

[Oleksandr Suvorov]

Property "force-mode" tells the driver to replace previously
initialized power-off kernel hook and allows gpio-poweroff to
probe and operate successfully in any case.

Signed-off-by: Oleksandr Suvorov <oleksandr.suvo...@toradex.com>
---

Changes in v2:
Call next pm_power_off handler if the current one
fails to power system off.

 drivers/power/reset/gpio-poweroff.c | 34 ++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/drivers/power/reset/gpio-poweroff.c 
b/drivers/power/reset/gpio-poweroff.c
index 6a4bbb506551..94056af9ba0d 100644
--- a/drivers/power/reset/gpio-poweroff.c
+++ b/drivers/power/reset/gpio-poweroff.c
@@ -24,6 +24,7 @@ static struct gpio_desc *reset_gpio;
 static u32 timeout = DEFAULT_TIMEOUT_MS;
 static u32 active_delay = 100;
 static u32 inactive_delay = 100;
+static void (*next_pm_power_off)(void);
 
 static void gpio_poweroff_do_poweroff(void)
 {
@@ -43,20 +44,41 @@ static void gpio_poweroff_do_poweroff(void)
        /* give it some time */
        mdelay(timeout);
 
+       /*
+        * The kernel should not reach this code. If it does, fall back to
+        * the next registered power off method.
+        */
+       if (next_pm_power_off)
+               next_pm_power_off();
+
        WARN_ON(1);
 }
 
 static int gpio_poweroff_probe(struct platform_device *pdev)
 {
        bool input = false;
+       bool force = false;
        enum gpiod_flags flags;
 
-       /* If a pm_power_off function has already been added, leave it alone */
+
+       force = device_property_read_bool(&pdev->dev, "force-mode");
+
+       /*
+        * If a pm_power_off function has already been added, leave it alone,
+        * if force-mode is not enabled.
+        */
        if (pm_power_off != NULL) {
-               dev_err(&pdev->dev,
-                       "%s: pm_power_off function already registered",
-                      __func__);
-               return -EBUSY;
+               if (force) {
+                       dev_warn(&pdev->dev,
+                                "%s: pm_power_off function replaced",
+                                __func__);
+                       next_pm_power_off = pm_power_off;
+               } else {
+                       dev_err(&pdev->dev,
+                               "%s: pm_power_off function already registered",
+                               __func__);
+                       return -EBUSY;
+               }
        }
 
        input = device_property_read_bool(&pdev->dev, "input");
@@ -81,7 +103,7 @@ static int gpio_poweroff_probe(struct platform_device *pdev)
 static int gpio_poweroff_remove(struct platform_device *pdev)
 {
        if (pm_power_off == &gpio_poweroff_do_poweroff)
-               pm_power_off = NULL;
+               pm_power_off = next_pm_power_off;
 
        return 0;
 }
-- 
2.20.1