1/* 2 * ledtrig-gio.c - LED Trigger Based on GPIO events 3 * 4 * Copyright 2009 Felipe Balbi <me@felipebalbi.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 */ 11 12#include <linux/module.h> 13#include <linux/kernel.h> 14#include <linux/init.h> 15#include <linux/gpio.h> 16#include <linux/interrupt.h> 17#include <linux/workqueue.h> 18#include <linux/leds.h> 19#include <linux/slab.h> 20#include "leds.h" 21 22struct gpio_trig_data { 23 struct led_classdev *led; 24 struct work_struct work; 25 26 unsigned desired_brightness; /* desired brightness when led is on */ 27 unsigned inverted; /* true when gpio is inverted */ 28 unsigned gpio; /* gpio that triggers the leds */ 29}; 30 31static irqreturn_t gpio_trig_irq(int irq, void *_led) 32{ 33 struct led_classdev *led = _led; 34 struct gpio_trig_data *gpio_data = led->trigger_data; 35 36 /* just schedule_work since gpio_get_value can sleep */ 37 schedule_work(&gpio_data->work); 38 39 return IRQ_HANDLED; 40}; 41 42static void gpio_trig_work(struct work_struct *work) 43{ 44 struct gpio_trig_data *gpio_data = container_of(work, 45 struct gpio_trig_data, work); 46 int tmp; 47 48 if (!gpio_data->gpio) 49 return; 50 51 tmp = gpio_get_value(gpio_data->gpio); 52 if (gpio_data->inverted) 53 tmp = !tmp; 54 55 if (tmp) { 56 if (gpio_data->desired_brightness) 57 led_set_brightness(gpio_data->led, 58 gpio_data->desired_brightness); 59 else 60 led_set_brightness(gpio_data->led, LED_FULL); 61 } else { 62 led_set_brightness(gpio_data->led, LED_OFF); 63 } 64} 65 66static ssize_t gpio_trig_brightness_show(struct device *dev, 67 struct device_attribute *attr, char *buf) 68{ 69 struct led_classdev *led = dev_get_drvdata(dev); 70 struct gpio_trig_data *gpio_data = led->trigger_data; 71 72 return sprintf(buf, "%u\n", gpio_data->desired_brightness); 73} 74 75static ssize_t gpio_trig_brightness_store(struct device *dev, 76 struct device_attribute *attr, const char *buf, size_t n) 77{ 78 struct led_classdev *led = dev_get_drvdata(dev); 79 struct gpio_trig_data *gpio_data = led->trigger_data; 80 unsigned desired_brightness; 81 int ret; 82 83 ret = sscanf(buf, "%u", &desired_brightness); 84 if (ret < 1 || desired_brightness > 255) { 85 dev_err(dev, "invalid value\n"); 86 return -EINVAL; 87 } 88 89 gpio_data->desired_brightness = desired_brightness; 90 91 return n; 92} 93static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show, 94 gpio_trig_brightness_store); 95 96static ssize_t gpio_trig_inverted_show(struct device *dev, 97 struct device_attribute *attr, char *buf) 98{ 99 struct led_classdev *led = dev_get_drvdata(dev); 100 struct gpio_trig_data *gpio_data = led->trigger_data; 101 102 return sprintf(buf, "%s\n", gpio_data->inverted ? "yes" : "no"); 103} 104 105static ssize_t gpio_trig_inverted_store(struct device *dev, 106 struct device_attribute *attr, const char *buf, size_t n) 107{ 108 struct led_classdev *led = dev_get_drvdata(dev); 109 struct gpio_trig_data *gpio_data = led->trigger_data; 110 unsigned inverted; 111 int ret; 112 113 ret = sscanf(buf, "%u", &inverted); 114 if (ret < 1) { 115 dev_err(dev, "invalid value\n"); 116 return -EINVAL; 117 } 118 119 gpio_data->inverted = !!inverted; 120 121 /* After inverting, we need to update the LED. */ 122 schedule_work(&gpio_data->work); 123 124 return n; 125} 126static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show, 127 gpio_trig_inverted_store); 128 129static ssize_t gpio_trig_gpio_show(struct device *dev, 130 struct device_attribute *attr, char *buf) 131{ 132 struct led_classdev *led = dev_get_drvdata(dev); 133 struct gpio_trig_data *gpio_data = led->trigger_data; 134 135 return sprintf(buf, "%u\n", gpio_data->gpio); 136} 137 138static ssize_t gpio_trig_gpio_store(struct device *dev, 139 struct device_attribute *attr, const char *buf, size_t n) 140{ 141 struct led_classdev *led = dev_get_drvdata(dev); 142 struct gpio_trig_data *gpio_data = led->trigger_data; 143 unsigned gpio; 144 int ret; 145 146 ret = sscanf(buf, "%u", &gpio); 147 if (ret < 1) { 148 dev_err(dev, "couldn't read gpio number\n"); 149 flush_work(&gpio_data->work); 150 return -EINVAL; 151 } 152 153 if (gpio_data->gpio == gpio) 154 return n; 155 156 if (!gpio) { 157 if (gpio_data->gpio != 0) 158 free_irq(gpio_to_irq(gpio_data->gpio), led); 159 gpio_data->gpio = 0; 160 return n; 161 } 162 163 ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq, 164 IRQF_SHARED | IRQF_TRIGGER_RISING 165 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led); 166 if (ret) { 167 dev_err(dev, "request_irq failed with error %d\n", ret); 168 } else { 169 if (gpio_data->gpio != 0) 170 free_irq(gpio_to_irq(gpio_data->gpio), led); 171 gpio_data->gpio = gpio; 172 } 173 174 return ret ? ret : n; 175} 176static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store); 177 178static void gpio_trig_activate(struct led_classdev *led) 179{ 180 struct gpio_trig_data *gpio_data; 181 int ret; 182 183 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL); 184 if (!gpio_data) 185 return; 186 187 ret = device_create_file(led->dev, &dev_attr_gpio); 188 if (ret) 189 goto err_gpio; 190 191 ret = device_create_file(led->dev, &dev_attr_inverted); 192 if (ret) 193 goto err_inverted; 194 195 ret = device_create_file(led->dev, &dev_attr_desired_brightness); 196 if (ret) 197 goto err_brightness; 198 199 gpio_data->led = led; 200 led->trigger_data = gpio_data; 201 INIT_WORK(&gpio_data->work, gpio_trig_work); 202 203 return; 204 205err_brightness: 206 device_remove_file(led->dev, &dev_attr_inverted); 207 208err_inverted: 209 device_remove_file(led->dev, &dev_attr_gpio); 210 211err_gpio: 212 kfree(gpio_data); 213} 214 215static void gpio_trig_deactivate(struct led_classdev *led) 216{ 217 struct gpio_trig_data *gpio_data = led->trigger_data; 218 219 if (gpio_data) { 220 device_remove_file(led->dev, &dev_attr_gpio); 221 device_remove_file(led->dev, &dev_attr_inverted); 222 device_remove_file(led->dev, &dev_attr_desired_brightness); 223 flush_work(&gpio_data->work); 224 if (gpio_data->gpio != 0) 225 free_irq(gpio_to_irq(gpio_data->gpio), led); 226 kfree(gpio_data); 227 } 228} 229 230static struct led_trigger gpio_led_trigger = { 231 .name = "gpio", 232 .activate = gpio_trig_activate, 233 .deactivate = gpio_trig_deactivate, 234}; 235 236static int __init gpio_trig_init(void) 237{ 238 return led_trigger_register(&gpio_led_trigger); 239} 240module_init(gpio_trig_init); 241 242static void __exit gpio_trig_exit(void) 243{ 244 led_trigger_unregister(&gpio_led_trigger); 245} 246module_exit(gpio_trig_exit); 247 248MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>"); 249MODULE_DESCRIPTION("GPIO LED trigger"); 250MODULE_LICENSE("GPL"); 251