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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | // 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"); |