drivers/leds/leds-pwm.c

   1 /*
   2  * linux/drivers/leds-pwm.c
   3  *
   4  * simple PWM based LED control
   5  *
   6  * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
   7  *
   8  * based on leds-gpio.c by Raphael Assenat <raph@8d.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/fb.h>
  20 #include <linux/leds.h>
  21 #include <linux/err.h>
  22 #include <linux/pwm.h>
  23 #include <linux/leds_pwm.h>
  24 #include <linux/slab.h>
  25
  26 struct led_pwm_data {
  27         struct led_classdev     cdev;
  28         struct pwm_device       *pwm;
  29         unsigned int            active_low;
  30         unsigned int            period;
  31         int                     duty;
  32         bool                    can_sleep;
  33 };
  34
  35 struct led_pwm_priv {
  36         int num_leds;
  37         struct led_pwm_data leds[0];
  38 };
  39
  40 static void __led_pwm_set(struct led_pwm_data *led_dat)
  41 {
  42         int new_duty = led_dat->duty;
  43
  44         pwm_config(led_dat->pwm, new_duty, led_dat->period);
  45
  46         if (new_duty == 0)
  47                 pwm_disable(led_dat->pwm);
  48         else
  49                 pwm_enable(led_dat->pwm);
  50 }
  51
  52 static void led_pwm_set(struct led_classdev *led_cdev,
  53         enum led_brightness brightness)
  54 {
  55         struct led_pwm_data *led_dat =
  56                 container_of(led_cdev, struct led_pwm_data, cdev);
  57         unsigned int max = led_dat->cdev.max_brightness;
  58         unsigned long long duty =  led_dat->period;
  59
  60         duty *= brightness;
  61         do_div(duty, max);
  62
  63         if (led_dat->active_low)
  64                 duty = led_dat->period - duty;
  65
  66         led_dat->duty = duty;
  67
  68         __led_pwm_set(led_dat);
  69 }
  70
  71 static int led_pwm_set_blocking(struct led_classdev *led_cdev,
  72         enum led_brightness brightness)
  73 {
  74         led_pwm_set(led_cdev, brightness);
  75         return 0;
  76 }
  77
  78 static inline size_t sizeof_pwm_leds_priv(int num_leds)
  79 {
  80         return sizeof(struct led_pwm_priv) +
  81                       (sizeof(struct led_pwm_data) * num_leds);
  82 }
  83
  84 static void led_pwm_cleanup(struct led_pwm_priv *priv)
  85 {
  86         while (priv->num_leds--)
  87                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
  88 }
  89
  90 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
  91                        struct led_pwm *led, struct device_node *child)
  92 {
  93         struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
  94         struct pwm_args pargs;
  95         int ret;
  96
  97         led_data->active_low = led->active_low;
  98         led_data->cdev.name = led->name;
  99         led_data->cdev.default_trigger = led->default_trigger;
 100         led_data->cdev.brightness = LED_OFF;
 101         led_data->cdev.max_brightness = led->max_brightness;
 102         led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
 103
 104         if (child)
 105                 led_data->pwm = devm_of_pwm_get(dev, child, NULL);
 106         else
 107                 led_data->pwm = devm_pwm_get(dev, led->name);
 108         if (IS_ERR(led_data->pwm)) {
 109                 ret = PTR_ERR(led_data->pwm);
 110                 dev_err(dev, "unable to request PWM for %s: %d\n",
 111                         led->name, ret);
 112                 return ret;
 113         }
 114
 115         led_data->can_sleep = pwm_can_sleep(led_data->pwm);
 116         if (!led_data->can_sleep)
 117                 led_data->cdev.brightness_set = led_pwm_set;
 118         else
 119                 led_data->cdev.brightness_set_blocking = led_pwm_set_blocking;
 120
 121         /*
 122          * FIXME: pwm_apply_args() should be removed when switching to the
 123          * atomic PWM API.
 124          */
 125         pwm_apply_args(led_data->pwm);
 126
 127         pwm_get_args(led_data->pwm, &pargs);
 128
 129         led_data->period = pargs.period;
 130         if (!led_data->period && (led->pwm_period_ns > 0))
 131                 led_data->period = led->pwm_period_ns;
 132
 133         ret = led_classdev_register(dev, &led_data->cdev);
 134         if (ret == 0) {
 135                 priv->num_leds++;
 136                 led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
 137         } else {
 138                 dev_err(dev, "failed to register PWM led for %s: %d\n",
 139                         led->name, ret);
 140         }
 141
 142         return ret;
 143 }
 144
 145 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
 146 {
 147         struct device_node *child;
 148         struct led_pwm led;
 149         int ret = 0;
 150
 151         memset(&led, 0, sizeof(led));
 152
 153         for_each_child_of_node(dev->of_node, child) {
 154                 led.name = of_get_property(child, "label", NULL) ? :
 155                            child->name;
 156
 157                 led.default_trigger = of_get_property(child,
 158                                                 "linux,default-trigger", NULL);
 159                 led.active_low = of_property_read_bool(child, "active-low");
 160                 of_property_read_u32(child, "max-brightness",
 161                                      &led.max_brightness);
 162
 163                 ret = led_pwm_add(dev, priv, &led, child);
 164                 if (ret) {
 165                         of_node_put(child);
 166                         break;
 167                 }
 168         }
 169
 170         return ret;
 171 }
 172
 173 static int led_pwm_probe(struct platform_device *pdev)
 174 {
 175         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 176         struct led_pwm_priv *priv;
 177         int count, i;
 178         int ret = 0;
 179
 180         if (pdata)
 181                 count = pdata->num_leds;
 182         else
 183                 count = of_get_child_count(pdev->dev.of_node);
 184
 185         if (!count)
 186                 return -EINVAL;
 187
 188         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
 189                             GFP_KERNEL);
 190         if (!priv)
 191                 return -ENOMEM;
 192
 193         if (pdata) {
 194                 for (i = 0; i < count; i++) {
 195                         ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
 196                                           NULL);
 197                         if (ret)
 198                                 break;
 199                 }
 200         } else {
 201                 ret = led_pwm_create_of(&pdev->dev, priv);
 202         }
 203
 204         if (ret) {
 205                 led_pwm_cleanup(priv);
 206                 return ret;
 207         }
 208
 209         platform_set_drvdata(pdev, priv);
 210
 211         return 0;
 212 }
 213
 214 static int led_pwm_remove(struct platform_device *pdev)
 215 {
 216         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
 217
 218         led_pwm_cleanup(priv);
 219
 220         return 0;
 221 }
 222
 223 static const struct of_device_id of_pwm_leds_match[] = {
 224         { .compatible = "pwm-leds", },
 225         {},
 226 };
 227 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 228
 229 static struct platform_driver led_pwm_driver = {
 230         .probe          = led_pwm_probe,
 231         .remove         = led_pwm_remove,
 232         .driver         = {
 233                 .name   = "leds_pwm",
 234                 .of_match_table = of_pwm_leds_match,
 235         },
 236 };
 237
 238 module_platform_driver(led_pwm_driver);
 239
 240 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 241 MODULE_DESCRIPTION("generic PWM LED driver");
 242 MODULE_LICENSE("GPL v2");
 243 MODULE_ALIAS("platform:leds-pwm");