leds: Teach leds-gpio to handle timer-unsafe GPIOs

Teach the new leds-gpio driver that some GPIOs can't be accessed from
timer callbacks ... which is how all today's standard triggers use them.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>

1 files changed, 26 insertions, 1 deletions

diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 431dcb61902c..47d90db280ce 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -13,14 +13,26 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/leds.h>
+#include <linux/workqueue.h>
+
 #include <asm/gpio.h>
 
 struct gpio_led_data {
         struct led_classdev cdev;
         unsigned gpio;
+        struct work_struct work;
+        u8 new_level;
+        u8 can_sleep;
         u8 active_low;
 };
 
+static void gpio_led_work(struct work_struct *work)
+{
+        struct gpio_led_data    *led_dat =
+                container_of(work, struct gpio_led_data, work);
+
+        gpio_set_value_cansleep(led_dat->gpio, led_dat->new_level);
+}
 
 static void gpio_led_set(struct led_classdev *led_cdev,
         enum led_brightness value)
@@ -37,7 +49,15 @@ static void gpio_led_set(struct led_classdev *led_cdev,
         if (led_dat->active_low)
                 level = !level;
 
-        gpio_set_value(led_dat->gpio, level);
+        /* setting GPIOs with I2C/etc requires a preemptible task context */
+        if (led_dat->can_sleep) {
+                if (preempt_count()) {
+                        led_dat->new_level = level;
+                        schedule_work(&led_dat->work);
+                } else
+                        gpio_set_value_cansleep(led_dat->gpio, level);
+        } else
+                gpio_set_value(led_dat->gpio, level);
 }
 
 static int __init gpio_led_probe(struct platform_device *pdev)
@@ -62,6 +82,7 @@ static int __init gpio_led_probe(struct platform_device *pdev)
                 led_dat->cdev.name = cur_led->name;
                 led_dat->cdev.default_trigger = cur_led->default_trigger;
                 led_dat->gpio = cur_led->gpio;
+                led_dat->can_sleep = gpio_cansleep(cur_led->gpio);
                 led_dat->active_low = cur_led->active_low;
                 led_dat->cdev.brightness_set = gpio_led_set;
                 led_dat->cdev.brightness = cur_led->active_low ? LED_FULL : LED_OFF;
@@ -77,6 +98,8 @@ static int __init gpio_led_probe(struct platform_device *pdev)
                         gpio_free(led_dat->gpio);
                         goto err;
                 }
+
+                INIT_WORK(&led_dat->work, gpio_led_work);
         }
 
         platform_set_drvdata(pdev, leds_data);
@@ -90,6 +113,8 @@ err:
                         gpio_free(leds_data[i].gpio);
                 }
         }
+
+        flush_scheduled_work();
         kfree(leds_data);
 
         return ret;