1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Backlight emulation LED trigger
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>
6*4882a593Smuzhiyun * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun
9*4882a593Smuzhiyun #include <linux/module.h>
10*4882a593Smuzhiyun #include <linux/kernel.h>
11*4882a593Smuzhiyun #include <linux/slab.h>
12*4882a593Smuzhiyun #include <linux/init.h>
13*4882a593Smuzhiyun #include <linux/fb.h>
14*4882a593Smuzhiyun #include <linux/leds.h>
15*4882a593Smuzhiyun #include "../leds.h"
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #define BLANK 1
18*4882a593Smuzhiyun #define UNBLANK 0
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun struct bl_trig_notifier {
21*4882a593Smuzhiyun struct led_classdev *led;
22*4882a593Smuzhiyun int brightness;
23*4882a593Smuzhiyun int old_status;
24*4882a593Smuzhiyun struct notifier_block notifier;
25*4882a593Smuzhiyun unsigned invert;
26*4882a593Smuzhiyun };
27*4882a593Smuzhiyun
fb_notifier_callback(struct notifier_block * p,unsigned long event,void * data)28*4882a593Smuzhiyun static int fb_notifier_callback(struct notifier_block *p,
29*4882a593Smuzhiyun unsigned long event, void *data)
30*4882a593Smuzhiyun {
31*4882a593Smuzhiyun struct bl_trig_notifier *n = container_of(p,
32*4882a593Smuzhiyun struct bl_trig_notifier, notifier);
33*4882a593Smuzhiyun struct led_classdev *led = n->led;
34*4882a593Smuzhiyun struct fb_event *fb_event = data;
35*4882a593Smuzhiyun int *blank;
36*4882a593Smuzhiyun int new_status;
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun /* If we aren't interested in this event, skip it immediately ... */
39*4882a593Smuzhiyun if (event != FB_EVENT_BLANK)
40*4882a593Smuzhiyun return 0;
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun blank = fb_event->data;
43*4882a593Smuzhiyun new_status = *blank ? BLANK : UNBLANK;
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun if (new_status == n->old_status)
46*4882a593Smuzhiyun return 0;
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun if ((n->old_status == UNBLANK) ^ n->invert) {
49*4882a593Smuzhiyun n->brightness = led->brightness;
50*4882a593Smuzhiyun led_set_brightness_nosleep(led, LED_OFF);
51*4882a593Smuzhiyun } else {
52*4882a593Smuzhiyun led_set_brightness_nosleep(led, n->brightness);
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun n->old_status = new_status;
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun return 0;
58*4882a593Smuzhiyun }
59*4882a593Smuzhiyun
bl_trig_invert_show(struct device * dev,struct device_attribute * attr,char * buf)60*4882a593Smuzhiyun static ssize_t bl_trig_invert_show(struct device *dev,
61*4882a593Smuzhiyun struct device_attribute *attr, char *buf)
62*4882a593Smuzhiyun {
63*4882a593Smuzhiyun struct bl_trig_notifier *n = led_trigger_get_drvdata(dev);
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun return sprintf(buf, "%u\n", n->invert);
66*4882a593Smuzhiyun }
67*4882a593Smuzhiyun
bl_trig_invert_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t num)68*4882a593Smuzhiyun static ssize_t bl_trig_invert_store(struct device *dev,
69*4882a593Smuzhiyun struct device_attribute *attr, const char *buf, size_t num)
70*4882a593Smuzhiyun {
71*4882a593Smuzhiyun struct led_classdev *led = led_trigger_get_led(dev);
72*4882a593Smuzhiyun struct bl_trig_notifier *n = led_trigger_get_drvdata(dev);
73*4882a593Smuzhiyun unsigned long invert;
74*4882a593Smuzhiyun int ret;
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun ret = kstrtoul(buf, 10, &invert);
77*4882a593Smuzhiyun if (ret < 0)
78*4882a593Smuzhiyun return ret;
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun if (invert > 1)
81*4882a593Smuzhiyun return -EINVAL;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun n->invert = invert;
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun /* After inverting, we need to update the LED. */
86*4882a593Smuzhiyun if ((n->old_status == BLANK) ^ n->invert)
87*4882a593Smuzhiyun led_set_brightness_nosleep(led, LED_OFF);
88*4882a593Smuzhiyun else
89*4882a593Smuzhiyun led_set_brightness_nosleep(led, n->brightness);
90*4882a593Smuzhiyun
91*4882a593Smuzhiyun return num;
92*4882a593Smuzhiyun }
93*4882a593Smuzhiyun static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun static struct attribute *bl_trig_attrs[] = {
96*4882a593Smuzhiyun &dev_attr_inverted.attr,
97*4882a593Smuzhiyun NULL,
98*4882a593Smuzhiyun };
99*4882a593Smuzhiyun ATTRIBUTE_GROUPS(bl_trig);
100*4882a593Smuzhiyun
bl_trig_activate(struct led_classdev * led)101*4882a593Smuzhiyun static int bl_trig_activate(struct led_classdev *led)
102*4882a593Smuzhiyun {
103*4882a593Smuzhiyun int ret;
104*4882a593Smuzhiyun
105*4882a593Smuzhiyun struct bl_trig_notifier *n;
106*4882a593Smuzhiyun
107*4882a593Smuzhiyun n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
108*4882a593Smuzhiyun if (!n)
109*4882a593Smuzhiyun return -ENOMEM;
110*4882a593Smuzhiyun led_set_trigger_data(led, n);
111*4882a593Smuzhiyun
112*4882a593Smuzhiyun n->led = led;
113*4882a593Smuzhiyun n->brightness = led->brightness;
114*4882a593Smuzhiyun n->old_status = UNBLANK;
115*4882a593Smuzhiyun n->notifier.notifier_call = fb_notifier_callback;
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun ret = fb_register_client(&n->notifier);
118*4882a593Smuzhiyun if (ret)
119*4882a593Smuzhiyun dev_err(led->dev, "unable to register backlight trigger\n");
120*4882a593Smuzhiyun
121*4882a593Smuzhiyun return 0;
122*4882a593Smuzhiyun }
123*4882a593Smuzhiyun
bl_trig_deactivate(struct led_classdev * led)124*4882a593Smuzhiyun static void bl_trig_deactivate(struct led_classdev *led)
125*4882a593Smuzhiyun {
126*4882a593Smuzhiyun struct bl_trig_notifier *n = led_get_trigger_data(led);
127*4882a593Smuzhiyun
128*4882a593Smuzhiyun fb_unregister_client(&n->notifier);
129*4882a593Smuzhiyun kfree(n);
130*4882a593Smuzhiyun }
131*4882a593Smuzhiyun
132*4882a593Smuzhiyun static struct led_trigger bl_led_trigger = {
133*4882a593Smuzhiyun .name = "backlight",
134*4882a593Smuzhiyun .activate = bl_trig_activate,
135*4882a593Smuzhiyun .deactivate = bl_trig_deactivate,
136*4882a593Smuzhiyun .groups = bl_trig_groups,
137*4882a593Smuzhiyun };
138*4882a593Smuzhiyun module_led_trigger(bl_led_trigger);
139*4882a593Smuzhiyun
140*4882a593Smuzhiyun MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
141*4882a593Smuzhiyun MODULE_DESCRIPTION("Backlight emulation LED trigger");
142*4882a593Smuzhiyun MODULE_LICENSE("GPL v2");
143