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authorHenrique de Moraes Holschuh <hmh@hmh.eng.br>2008-03-18 09:47:48 +0000
committerRichard Purdie <rpurdie@rpsys.net>2008-04-24 23:37:42 +0100
commit29d76dfa29fe22583aefddccda0bc56aa81035dc (patch)
treefbae9207af63cb270b715a29ee7dc053d7b8a037 /drivers/leds
parentca3259b3603539e72faacc6821050ee889a52103 (diff)
downloadlinux-29d76dfa29fe22583aefddccda0bc56aa81035dc.tar.bz2
leds: Add support to leds with readable status
Some led hardware allows drivers to query the led state, and this patch adds a hook to let the led class take advantage of that information when available. Without this functionality, when access to the led hardware is not exclusive (i.e. firmware or hardware might change its state behind the kernel's back), reality goes out of sync with the led class' idea of what the led is doing, which is annoying at best. Behaviour for drivers that do not or cannot read the led status is unchanged. Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Diffstat (limited to 'drivers/leds')
-rw-r--r--drivers/leds/led-class.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index a8dd59ebedf8..ac05a928f764 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -24,6 +24,12 @@
static struct class *leds_class;
+static void led_update_brightness(struct led_classdev *led_cdev)
+{
+ if (led_cdev->brightness_get)
+ led_cdev->brightness = led_cdev->brightness_get(led_cdev);
+}
+
static ssize_t led_brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -31,6 +37,7 @@ static ssize_t led_brightness_show(struct device *dev,
ssize_t ret = 0;
/* no lock needed for this */
+ led_update_brightness(led_cdev);
sprintf(buf, "%u\n", led_cdev->brightness);
ret = strlen(buf) + 1;
@@ -113,6 +120,8 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
list_add_tail(&led_cdev->node, &leds_list);
up_write(&leds_list_lock);
+ led_update_brightness(led_cdev);
+
#ifdef CONFIG_LEDS_TRIGGERS
init_rwsem(&led_cdev->trigger_lock);