diff options
Diffstat (limited to 'drivers/leds/trigger/ledtrig-backlight.c')
| -rw-r--r-- | drivers/leds/trigger/ledtrig-backlight.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c new file mode 100644 index 000000000..59eca17d9 --- /dev/null +++ b/drivers/leds/trigger/ledtrig-backlight.c @@ -0,0 +1,168 @@ +/* + * Backlight emulation LED trigger + * + * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it> + * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/fb.h> +#include <linux/leds.h> +#include "../leds.h" + +#define BLANK 1 +#define UNBLANK 0 + +struct bl_trig_notifier { + struct led_classdev *led; + int brightness; + int old_status; + struct notifier_block notifier; + unsigned invert; +}; + +static int fb_notifier_callback(struct notifier_block *p, + unsigned long event, void *data) +{ + struct bl_trig_notifier *n = container_of(p, + struct bl_trig_notifier, notifier); + struct led_classdev *led = n->led; + struct fb_event *fb_event = data; + int *blank; + int new_status; + + /* If we aren't interested in this event, skip it immediately ... */ + if (event != FB_EVENT_BLANK) + return 0; + + blank = fb_event->data; + new_status = *blank ? BLANK : UNBLANK; + + if (new_status == n->old_status) + return 0; + + if ((n->old_status == UNBLANK) ^ n->invert) { + n->brightness = led->brightness; + led_set_brightness_async(led, LED_OFF); + } else { + led_set_brightness_async(led, n->brightness); + } + + n->old_status = new_status; + + return 0; +} + +static ssize_t bl_trig_invert_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct led_classdev *led = dev_get_drvdata(dev); + struct bl_trig_notifier *n = led->trigger_data; + + return sprintf(buf, "%u\n", n->invert); +} + +static ssize_t bl_trig_invert_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t num) +{ + struct led_classdev *led = dev_get_drvdata(dev); + struct bl_trig_notifier *n = led->trigger_data; + unsigned long invert; + int ret; + + ret = kstrtoul(buf, 10, &invert); + if (ret < 0) + return ret; + + if (invert > 1) + return -EINVAL; + + n->invert = invert; + + /* After inverting, we need to update the LED. */ + if ((n->old_status == BLANK) ^ n->invert) + led_set_brightness_async(led, LED_OFF); + else + led_set_brightness_async(led, n->brightness); + + return num; +} +static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store); + +static void bl_trig_activate(struct led_classdev *led) +{ + int ret; + + struct bl_trig_notifier *n; + + n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL); + led->trigger_data = n; + if (!n) { + dev_err(led->dev, "unable to allocate backlight trigger\n"); + return; + } + + ret = device_create_file(led->dev, &dev_attr_inverted); + if (ret) + goto err_invert; + + n->led = led; + n->brightness = led->brightness; + n->old_status = UNBLANK; + n->notifier.notifier_call = fb_notifier_callback; + + ret = fb_register_client(&n->notifier); + if (ret) + dev_err(led->dev, "unable to register backlight trigger\n"); + led->activated = true; + + return; + +err_invert: + led->trigger_data = NULL; + kfree(n); +} + +static void bl_trig_deactivate(struct led_classdev *led) +{ + struct bl_trig_notifier *n = + (struct bl_trig_notifier *) led->trigger_data; + + if (led->activated) { + device_remove_file(led->dev, &dev_attr_inverted); + fb_unregister_client(&n->notifier); + kfree(n); + led->activated = false; + } +} + +static struct led_trigger bl_led_trigger = { + .name = "backlight", + .activate = bl_trig_activate, + .deactivate = bl_trig_deactivate +}; + +static int __init bl_trig_init(void) +{ + return led_trigger_register(&bl_led_trigger); +} + +static void __exit bl_trig_exit(void) +{ + led_trigger_unregister(&bl_led_trigger); +} + +module_init(bl_trig_init); +module_exit(bl_trig_exit); + +MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); +MODULE_DESCRIPTION("Backlight emulation LED trigger"); +MODULE_LICENSE("GPL v2"); |