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/init.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/fb.h>
  21 #include <linux/leds.h>
  22 #include <linux/err.h>
  23 #include <linux/pwm.h>
  24 #include <linux/leds_pwm.h>
  25 #include <linux/slab.h>
  26
  27 struct led_pwm_data {
  28         struct led_classdev     cdev;
  29         struct pwm_device       *pwm;
  30         unsigned int            active_low;
  31         unsigned int            period;
  32 };
  33
  34 struct led_pwm_priv {
  35         int num_leds;
  36         struct led_pwm_data leds[0];
  37 };
  38
  39 static void led_pwm_set(struct led_classdev *led_cdev,
  40         enum led_brightness brightness)
  41 {
  42         struct led_pwm_data *led_dat =
  43                 container_of(led_cdev, struct led_pwm_data, cdev);
  44         unsigned int max = led_dat->cdev.max_brightness;
  45         unsigned int period =  led_dat->period;
  46
  47         if (brightness == 0) {
  48                 pwm_config(led_dat->pwm, 0, period);
  49                 pwm_disable(led_dat->pwm);
  50         } else {
  51                 pwm_config(led_dat->pwm, brightness * period / max, period);
  52                 pwm_enable(led_dat->pwm);
  53         }
  54 }
  55
  56 static inline size_t sizeof_pwm_leds_priv(int num_leds)
  57 {
  58         return sizeof(struct led_pwm_priv) +
  59                       (sizeof(struct led_pwm_data) * num_leds);
  60 }
  61
  62 static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
  63 {
  64         struct device_node *node = pdev->dev.of_node;
  65         struct device_node *child;
  66         struct led_pwm_priv *priv;
  67         int count, ret;
  68
  69         /* count LEDs in this device, so we know how much to allocate */
  70         count = of_get_child_count(node);
  71         if (!count)
  72                 return NULL;
  73
  74         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
  75                             GFP_KERNEL);
  76         if (!priv)
  77                 return NULL;
  78
  79         for_each_child_of_node(node, child) {
  80                 struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
  81
  82                 led_dat->cdev.name = of_get_property(child, "label",
  83                                                      NULL) ? : child->name;
  84
  85                 led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
  86                 if (IS_ERR(led_dat->pwm)) {
  87                         dev_err(&pdev->dev, "unable to request PWM for %s\n",
  88                                 led_dat->cdev.name);
  89                         goto err;
  90                 }
  91                 /* Get the period from PWM core when n*/
  92                 led_dat->period = pwm_get_period(led_dat->pwm);
  93
  94                 led_dat->cdev.default_trigger = of_get_property(child,
  95                                                 "linux,default-trigger", NULL);
  96                 of_property_read_u32(child, "max-brightness",
  97                                      &led_dat->cdev.max_brightness);
  98
  99                 led_dat->cdev.brightness_set = led_pwm_set;
 100                 led_dat->cdev.brightness = LED_OFF;
 101                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 102
 103                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 104                 if (ret < 0) {
 105                         dev_err(&pdev->dev, "failed to register for %s\n",
 106                                 led_dat->cdev.name);
 107                         of_node_put(child);
 108                         goto err;
 109                 }
 110                 priv->num_leds++;
 111         }
 112
 113         return priv;
 114 err:
 115         while (priv->num_leds--)
 116                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
 117
 118         return NULL;
 119 }
 120
 121 static int led_pwm_probe(struct platform_device *pdev)
 122 {
 123         struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 124         struct led_pwm_priv *priv;
 125         int i, ret = 0;
 126
 127         if (pdata && pdata->num_leds) {
 128                 priv = devm_kzalloc(&pdev->dev,
 129                                     sizeof_pwm_leds_priv(pdata->num_leds),
 130                                     GFP_KERNEL);
 131                 if (!priv)
 132                         return -ENOMEM;
 133
 134                 for (i = 0; i < pdata->num_leds; i++) {
 135                         struct led_pwm *cur_led = &pdata->leds[i];
 136                         struct led_pwm_data *led_dat = &priv->leds[i];
 137
 138                         led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
 139                         if (IS_ERR(led_dat->pwm)) {
 140                                 ret = PTR_ERR(led_dat->pwm);
 141                                 dev_err(&pdev->dev,
 142                                         "unable to request PWM for %s\n",
 143                                         cur_led->name);
 144                                 goto err;
 145                         }
 146
 147                         led_dat->cdev.name = cur_led->name;
 148                         led_dat->cdev.default_trigger = cur_led->default_trigger;
 149                         led_dat->active_low = cur_led->active_low;
 150                         led_dat->period = cur_led->pwm_period_ns;
 151                         led_dat->cdev.brightness_set = led_pwm_set;
 152                         led_dat->cdev.brightness = LED_OFF;
 153                         led_dat->cdev.max_brightness = cur_led->max_brightness;
 154                         led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 155
 156                         ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 157                         if (ret < 0)
 158                                 goto err;
 159                 }
 160                 priv->num_leds = pdata->num_leds;
 161         } else {
 162                 priv = led_pwm_create_of(pdev);
 163                 if (!priv)
 164                         return -ENODEV;
 165         }
 166
 167         platform_set_drvdata(pdev, priv);
 168
 169         return 0;
 170
 171 err:
 172         while (i--)
 173                 led_classdev_unregister(&priv->leds[i].cdev);
 174
 175         return ret;
 176 }
 177
 178 static int led_pwm_remove(struct platform_device *pdev)
 179 {
 180         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
 181         int i;
 182
 183         for (i = 0; i < priv->num_leds; i++)
 184                 led_classdev_unregister(&priv->leds[i].cdev);
 185
 186         return 0;
 187 }
 188
 189 static const struct of_device_id of_pwm_leds_match[] = {
 190         { .compatible = "pwm-leds", },
 191         {},
 192 };
 193 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 194
 195 static struct platform_driver led_pwm_driver = {
 196         .probe          = led_pwm_probe,
 197         .remove         = led_pwm_remove,
 198         .driver         = {
 199                 .name   = "leds_pwm",
 200                 .owner  = THIS_MODULE,
 201                 .of_match_table = of_match_ptr(of_pwm_leds_match),
 202         },
 203 };
 204
 205 module_platform_driver(led_pwm_driver);
 206
 207 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 208 MODULE_DESCRIPTION("PWM LED driver for PXA");
 209 MODULE_LICENSE("GPL");
 210 MODULE_ALIAS("platform:leds-pwm");