/* * 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 = fb_event->data; int new_status = *blank ? BLANK : UNBLANK; switch (event) { case FB_EVENT_BLANK : if (new_status == n->old_status) break; if ((n->old_status == UNBLANK) ^ n->invert) { n->brightness = led->brightness; __led_set_brightness(led, LED_OFF); } else { __led_set_brightness(led, n->brightness); } n->old_status = new_status; break; } 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 = strict_strtoul(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(led, LED_OFF); else __led_set_brightness(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");