diff options
Diffstat (limited to 'drivers/leds/trigger/ledtrig-backlight.c')
| -rw-r--r-- | drivers/leds/trigger/ledtrig-backlight.c | 142 |
1 files changed, 142 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..487577d22 --- /dev/null +++ b/drivers/leds/trigger/ledtrig-backlight.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Backlight emulation LED trigger + * + * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it> + * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it> + */ + +#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_nosleep(led, LED_OFF); + } else { + led_set_brightness_nosleep(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 bl_trig_notifier *n = led_trigger_get_drvdata(dev); + + 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 = led_trigger_get_led(dev); + struct bl_trig_notifier *n = led_trigger_get_drvdata(dev); + 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_nosleep(led, LED_OFF); + else + led_set_brightness_nosleep(led, n->brightness); + + return num; +} +static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store); + +static struct attribute *bl_trig_attrs[] = { + &dev_attr_inverted.attr, + NULL, +}; +ATTRIBUTE_GROUPS(bl_trig); + +static int bl_trig_activate(struct led_classdev *led) +{ + int ret; + + struct bl_trig_notifier *n; + + n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL); + if (!n) + return -ENOMEM; + led_set_trigger_data(led, n); + + 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"); + + return 0; +} + +static void bl_trig_deactivate(struct led_classdev *led) +{ + struct bl_trig_notifier *n = led_get_trigger_data(led); + + fb_unregister_client(&n->notifier); + kfree(n); +} + +static struct led_trigger bl_led_trigger = { + .name = "backlight", + .activate = bl_trig_activate, + .deactivate = bl_trig_deactivate, + .groups = bl_trig_groups, +}; +module_led_trigger(bl_led_trigger); + +MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); +MODULE_DESCRIPTION("Backlight emulation LED trigger"); +MODULE_LICENSE("GPL v2"); |