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