From 325253a6b2de4bdfa9ef0e28b5df8a4a4fe2b677 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Tue, 14 Jul 2009 17:06:02 +0100 Subject: backlight: Allow drivers to update the core, and generate events on changes Certain hardware will send us events when the backlight brightness changes. Add a function to update the value in the core, and additionally send a uevent so that userspace can pop up appropriate UI. The uevents are flagged depending on whether the update originated in the kernel or from userspace, making it easier to only display UI at the appropriate time. Signed-off-by: Matthew Garrett Signed-off-by: Richard Purdie --- drivers/video/backlight/backlight.c | 41 +++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) (limited to 'drivers/video') diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 157057c79ca..6e1446ae7f5 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -73,6 +73,26 @@ static inline void backlight_unregister_fb(struct backlight_device *bd) } #endif /* CONFIG_FB */ +static void backlight_generate_event(struct backlight_device *bd, + enum backlight_update_reason reason) +{ + char *envp[2]; + + switch (reason) { + case BACKLIGHT_UPDATE_SYSFS: + envp[0] = "SOURCE=sysfs"; + break; + case BACKLIGHT_UPDATE_HOTKEY: + envp[0] = "SOURCE=hotkey"; + break; + default: + envp[0] = "SOURCE=unknown"; + break; + } + envp[1] = NULL; + kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp); +} + static ssize_t backlight_show_power(struct device *dev, struct device_attribute *attr,char *buf) { @@ -142,6 +162,8 @@ static ssize_t backlight_store_brightness(struct device *dev, } mutex_unlock(&bd->ops_lock); + backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS); + return rc; } @@ -213,6 +235,25 @@ static struct device_attribute bl_device_attributes[] = { __ATTR_NULL, }; +/** + * backlight_force_update - tell the backlight subsystem that hardware state + * has changed + * @bd: the backlight device to update + * + * Updates the internal state of the backlight in response to a hardware event, + * and generate a uevent to notify userspace + */ +void backlight_force_update(struct backlight_device *bd, + enum backlight_update_reason reason) +{ + mutex_lock(&bd->ops_lock); + if (bd->ops && bd->ops->get_brightness) + bd->props.brightness = bd->ops->get_brightness(bd); + mutex_unlock(&bd->ops_lock); + backlight_generate_event(bd, reason); +} +EXPORT_SYMBOL(backlight_force_update); + /** * backlight_device_register - create and register a new object of * backlight_device class. -- cgit v1.2.3