leds: gpio: Support the "panic-indicator" firmware property

Calling a GPIO LEDs is quite likely to work even if the kernel
has paniced, so they are ideal to blink in this situation.
This commit adds support for the new "panic-indicator"
firmware property, allowing to mark a given LED to blink on
a kernel panic.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

3 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/leds/leds-gpio.txt b/Documentation/devicetree/bindings/leds/leds-gpio.txt
index fea1ebfe24a9..cbbeb1850910 100644
--- a/Documentation/devicetree/bindings/leds/leds-gpio.txt
+++ b/Documentation/devicetree/bindings/leds/leds-gpio.txt
@@ -23,6 +23,8 @@ LED sub-node properties:
   property is not present.
 - retain-state-suspended: (optional) The suspend state can be retained.Such
   as charge-led gpio.
+- panic-indicator : (optional)
+  see Documentation/devicetree/bindings/leds/common.txt
 
 Examples:
 
diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 61143f55597e..8229f063b483 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -127,6 +127,8 @@ static int create_gpio_led(const struct gpio_led *template,
         led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
         if (!template->retain_state_suspended)
                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+        if (template->panic_indicator)
+                led_dat->cdev.flags |= LED_PANIC_INDICATOR;
 
         ret = gpiod_direction_output(led_dat->gpiod, state);
         if (ret < 0)
@@ -200,6 +202,8 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 
                 if (fwnode_property_present(child, "retain-state-suspended"))
                         led.retain_state_suspended = 1;
+                if (fwnode_property_present(child, "panic-indicator"))
+                        led.panic_indicator = 1;
 
                 ret = create_gpio_led(&led, &priv->leds[priv->num_leds],
                                       dev, NULL);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 7e9fb00e15e8..d2b13066e781 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -365,6 +365,7 @@ struct gpio_led {
         unsigned        gpio;
         unsigned        active_low : 1;
         unsigned        retain_state_suspended : 1;
+        unsigned        panic_indicator : 1;
         unsigned        default_state : 2;
         /* default_state should be one of LEDS_GPIO_DEFSTATE_(ON|OFF|KEEP) */
         struct gpio_desc *gpiod;