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 22 struct 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 31 static 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 42 static 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_cansleep(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_nosleep(gpio_data->led, 58 gpio_data->desired_brightness); 59 else 60 led_set_brightness_nosleep(gpio_data->led, LED_FULL); 61 } else { 62 led_set_brightness_nosleep(gpio_data->led, LED_OFF); 63 } 64 } 65 66 static 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 75 static 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 } 93 static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show, 94 gpio_trig_brightness_store); 95 96 static 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, "%u\n", gpio_data->inverted); 103 } 104 105 static 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 long inverted; 111 int ret; 112 113 ret = kstrtoul(buf, 10, &inverted); 114 if (ret < 0) 115 return ret; 116 117 if (inverted > 1) 118 return -EINVAL; 119 120 gpio_data->inverted = inverted; 121 122 /* After inverting, we need to update the LED. */ 123 schedule_work(&gpio_data->work); 124 125 return n; 126 } 127 static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show, 128 gpio_trig_inverted_store); 129 130 static ssize_t gpio_trig_gpio_show(struct device *dev, 131 struct device_attribute *attr, char *buf) 132 { 133 struct led_classdev *led = dev_get_drvdata(dev); 134 struct gpio_trig_data *gpio_data = led->trigger_data; 135 136 return sprintf(buf, "%u\n", gpio_data->gpio); 137 } 138 139 static ssize_t gpio_trig_gpio_store(struct device *dev, 140 struct device_attribute *attr, const char *buf, size_t n) 141 { 142 struct led_classdev *led = dev_get_drvdata(dev); 143 struct gpio_trig_data *gpio_data = led->trigger_data; 144 unsigned gpio; 145 int ret; 146 147 ret = sscanf(buf, "%u", &gpio); 148 if (ret < 1) { 149 dev_err(dev, "couldn't read gpio number\n"); 150 flush_work(&gpio_data->work); 151 return -EINVAL; 152 } 153 154 if (gpio_data->gpio == gpio) 155 return n; 156 157 if (!gpio) { 158 if (gpio_data->gpio != 0) 159 free_irq(gpio_to_irq(gpio_data->gpio), led); 160 gpio_data->gpio = 0; 161 return n; 162 } 163 164 ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq, 165 IRQF_SHARED | IRQF_TRIGGER_RISING 166 | IRQF_TRIGGER_FALLING, "ledtrig-gpio", led); 167 if (ret) { 168 dev_err(dev, "request_irq failed with error %d\n", ret); 169 } else { 170 if (gpio_data->gpio != 0) 171 free_irq(gpio_to_irq(gpio_data->gpio), led); 172 gpio_data->gpio = gpio; 173 } 174 175 return ret ? ret : n; 176 } 177 static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store); 178 179 static void gpio_trig_activate(struct led_classdev *led) 180 { 181 struct gpio_trig_data *gpio_data; 182 int ret; 183 184 gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL); 185 if (!gpio_data) 186 return; 187 188 ret = device_create_file(led->dev, &dev_attr_gpio); 189 if (ret) 190 goto err_gpio; 191 192 ret = device_create_file(led->dev, &dev_attr_inverted); 193 if (ret) 194 goto err_inverted; 195 196 ret = device_create_file(led->dev, &dev_attr_desired_brightness); 197 if (ret) 198 goto err_brightness; 199 200 gpio_data->led = led; 201 led->trigger_data = gpio_data; 202 INIT_WORK(&gpio_data->work, gpio_trig_work); 203 led->activated = true; 204 205 return; 206 207 err_brightness: 208 device_remove_file(led->dev, &dev_attr_inverted); 209 210 err_inverted: 211 device_remove_file(led->dev, &dev_attr_gpio); 212 213 err_gpio: 214 kfree(gpio_data); 215 } 216 217 static void gpio_trig_deactivate(struct led_classdev *led) 218 { 219 struct gpio_trig_data *gpio_data = led->trigger_data; 220 221 if (led->activated) { 222 device_remove_file(led->dev, &dev_attr_gpio); 223 device_remove_file(led->dev, &dev_attr_inverted); 224 device_remove_file(led->dev, &dev_attr_desired_brightness); 225 flush_work(&gpio_data->work); 226 if (gpio_data->gpio != 0) 227 free_irq(gpio_to_irq(gpio_data->gpio), led); 228 kfree(gpio_data); 229 led->activated = false; 230 } 231 } 232 233 static struct led_trigger gpio_led_trigger = { 234 .name = "gpio", 235 .activate = gpio_trig_activate, 236 .deactivate = gpio_trig_deactivate, 237 }; 238 239 static int __init gpio_trig_init(void) 240 { 241 return led_trigger_register(&gpio_led_trigger); 242 } 243 module_init(gpio_trig_init); 244 245 static void __exit gpio_trig_exit(void) 246 { 247 led_trigger_unregister(&gpio_led_trigger); 248 } 249 module_exit(gpio_trig_exit); 250 251 MODULE_AUTHOR("Felipe Balbi <me@felipebalbi.com>"); 252 MODULE_DESCRIPTION("GPIO LED trigger"); 253 MODULE_LICENSE("GPL"); 254