drivers/leds/trigger/ledtrig-gpio.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ledtrig-gio.c - LED Trigger Based on GPIO events
   4  *
   5  * Copyright 2009 Felipe Balbi <me@felipebalbi.com>
   6  * Copyright 2023 Linus Walleij <linus.walleij@linaro.org>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/gpio/consumer.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/leds.h>
  15 #include <linux/slab.h>
  16 #include "../leds.h"
  17
  18 struct gpio_trig_data {
  19         struct led_classdev *led;
  20         unsigned desired_brightness;    /* desired brightness when led is on */
  21         struct gpio_desc *gpiod;        /* gpio that triggers the led */
  22 };
  23
  24 static irqreturn_t gpio_trig_irq(int irq, void *_led)
  25 {
  26         struct led_classdev *led = _led;
  27         struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
  28         int tmp;
  29
  30         tmp = gpiod_get_value_cansleep(gpio_data->gpiod);
  31         if (tmp) {
  32                 if (gpio_data->desired_brightness)
  33                         led_set_brightness_nosleep(gpio_data->led,
  34                                            gpio_data->desired_brightness);
  35                 else
  36                         led_set_brightness_nosleep(gpio_data->led, LED_FULL);
  37         } else {
  38                 led_set_brightness_nosleep(gpio_data->led, LED_OFF);
  39         }
  40
  41         return IRQ_HANDLED;
  42 }
  43
  44 static ssize_t desired_brightness_show(struct device *dev,
  45                 struct device_attribute *attr, char *buf)
  46 {
  47         struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
  48
  49         return sysfs_emit(buf, "%u\n", gpio_data->desired_brightness);
  50 }
  51
  52 static ssize_t desired_brightness_store(struct device *dev,
  53                 struct device_attribute *attr, const char *buf, size_t n)
  54 {
  55         struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
  56         u8 desired_brightness;
  57         int ret;
  58
  59         ret = kstrtou8(buf, 10, &desired_brightness);
  60         if (ret)
  61                 return ret;
  62
  63         gpio_data->desired_brightness = desired_brightness;
  64
  65         return n;
  66 }
  67 static DEVICE_ATTR_RW(desired_brightness);
  68
  69 static struct attribute *gpio_trig_attrs[] = {
  70         &dev_attr_desired_brightness.attr,
  71         NULL
  72 };
  73 ATTRIBUTE_GROUPS(gpio_trig);
  74
  75 static int gpio_trig_activate(struct led_classdev *led)
  76 {
  77         struct gpio_trig_data *gpio_data;
  78         struct device *dev = led->dev;
  79         int ret;
  80
  81         gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
  82         if (!gpio_data)
  83                 return -ENOMEM;
  84
  85         /*
  86          * The generic property "trigger-sources" is followed,
  87          * and we hope that this is a GPIO.
  88          */
  89         gpio_data->gpiod = gpiod_get_optional(dev, "trigger-sources", GPIOD_IN);
  90         if (IS_ERR(gpio_data->gpiod)) {
  91                 ret = PTR_ERR(gpio_data->gpiod);
  92                 kfree(gpio_data);
  93                 return ret;
  94         }
  95         if (!gpio_data->gpiod) {
  96                 dev_err(dev, "no valid GPIO for the trigger\n");
  97                 kfree(gpio_data);
  98                 return -EINVAL;
  99         }
 100
 101         gpiod_set_consumer_name(gpio_data->gpiod, "led-trigger");
 102
 103         gpio_data->led = led;
 104         led_set_trigger_data(led, gpio_data);
 105
 106         ret = request_threaded_irq(gpiod_to_irq(gpio_data->gpiod), NULL, gpio_trig_irq,
 107                         IRQF_ONESHOT | IRQF_SHARED | IRQF_TRIGGER_RISING
 108                         | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
 109         if (ret) {
 110                 dev_err(dev, "request_irq failed with error %d\n", ret);
 111                 gpiod_put(gpio_data->gpiod);
 112                 kfree(gpio_data);
 113                 return ret;
 114         }
 115
 116         /* Finally update the LED to initial status */
 117         gpio_trig_irq(0, led);
 118
 119         return 0;
 120 }
 121
 122 static void gpio_trig_deactivate(struct led_classdev *led)
 123 {
 124         struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
 125
 126         free_irq(gpiod_to_irq(gpio_data->gpiod), led);
 127         gpiod_put(gpio_data->gpiod);
 128         kfree(gpio_data);
 129 }
 130
 131 static struct led_trigger gpio_led_trigger = {
 132         .name           = "gpio",
 133         .activate       = gpio_trig_activate,
 134         .deactivate     = gpio_trig_deactivate,
 135         .groups         = gpio_trig_groups,
 136 };
 137 module_led_trigger(gpio_led_trigger);
 138
 139 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>");
 140 MODULE_DESCRIPTION("GPIO LED trigger");
 141 MODULE_LICENSE("GPL v2");