kernel/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 #include <linux/workqueue.h>
  26
  27 struct led_pwm_data {
  28         struct led_classdev     cdev;
  29         struct pwm_device       *pwm;
  30         struct work_struct      work;
  31         unsigned int            active_low;
  32         unsigned int            period;
  33         int                     duty;
  34         bool                    can_sleep;
  35 };
  36
  37 struct led_pwm_priv {
  38         int num_leds;
  39         struct led_pwm_data leds[0];
  40 };
  41
  42 static void __led_pwm_set(struct led_pwm_data *led_dat)
  43 {
  44         int new_duty = led_dat->duty;
  45
  46         pwm_config(led_dat->pwm, new_duty, led_dat->period);
  47
  48         if (new_duty == 0)
  49                 pwm_disable(led_dat->pwm);
  50         else
  51                 pwm_enable(led_dat->pwm);
  52 }
  53
  54 static void led_pwm_work(struct work_struct *work)
  55 {
  56         struct led_pwm_data *led_dat =
  57                 container_of(work, struct led_pwm_data, work);
  58
  59         __led_pwm_set(led_dat);
  60 }
  61
  62 static void led_pwm_set(struct led_classdev *led_cdev,
  63         enum led_brightness brightness)
  64 {
  65         struct led_pwm_data *led_dat =
  66                 container_of(led_cdev, struct led_pwm_data, cdev);
  67         unsigned int max = led_dat->cdev.max_brightness;
  68         unsigned long long duty =  led_dat->period;
  69
  70         duty *= brightness;
  71         do_div(duty, max);
  72
  73         if (led_dat->active_low)
  74                 duty = led_dat->period - duty;
  75
  76         led_dat->duty = duty;
  77
  78         if (led_dat->can_sleep)
  79                 schedule_work(&led_dat->work);
  80         else
  81                 __led_pwm_set(led_dat);
  82 }
  83
  84 static inline size_t sizeof_pwm_leds_priv(int num_leds)
  85 {
  86         return sizeof(struct led_pwm_priv) +
  87                       (sizeof(struct led_pwm_data) * num_leds);
  88 }
  89
  90 static void led_pwm_cleanup(struct led_pwm_priv *priv)
  91 {
  92         while (priv->num_leds--) {
  93                 led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
  94                 if (priv->leds[priv->num_leds].can_sleep)
  95                         cancel_work_sync(&priv->leds[priv->num_leds].work);
  96         }
  97 }
  98
  99 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
 100                        struct led_pwm *led, struct device_node *child)
 101 {
 102         struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
 103         int ret;
 104
 105         led_data->active_low = led->active_low;
 106         led_data->cdev.name = led->name;
 107         led_data->cdev.default_trigger = led->default_trigger;
 108         led_data->cdev.brightness_set = led_pwm_set;
 109         led_data->cdev.brightness = LED_OFF;
 110         led_data->cdev.max_brightness = led->max_brightness;
 111         led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
 112
 113         if (child)
 114                 led_data->pwm = devm_of_pwm_get(dev, child, NULL);
 115         else
 116                 led_data->pwm = devm_pwm_get(dev, led->name);
 117         if (IS_ERR(led_data->pwm)) {
 118                 ret = PTR_ERR(led_data->pwm);
 119                 dev_err(dev, "unable to request PWM for %s: %d\n",
 120                         led->name, ret);
 121                 return ret;
 122         }
 123
 124         led_data->can_sleep = pwm_can_sleep(led_data->pwm);
 125         if (led_data->can_sleep)
 126                 INIT_WORK(&led_data->work, led_pwm_work);
 127
 128         led_data->period = pwm_get_period(led_data->pwm);
 129         if (!led_data->period && (led->pwm_period_ns > 0))
 130                 led_data->period = led->pwm_period_ns;
 131
 132         ret = led_classdev_register(dev, &led_data->cdev);
 133         if (ret == 0) {
 134                 priv->num_leds++;
 135         } else {
 136                 dev_err(dev, "failed to register PWM led for %s: %d\n",
 137                         led->name, ret);
 138         }
 139
 140         return ret;
 141 }
 142
 143 static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
 144 {
 145         struct device_node *child;
 146         struct led_pwm led;
 147         int ret = 0;
 148
 149         memset(&led, 0, sizeof(led));
 150
 151         for_each_child_of_node(dev->of_node, child) {
 152                 led.name = of_get_property(child, "label", NULL) ? :
 153                            child->name;
 154
 155                 led.default_trigger = of_get_property(child,
 156                                                 "linux,default-trigger", NULL);
 157                 led.active_low = of_property_read_bool(child, "active-low");
 158                 of_property_read_u32(child, "max-brightness",
 159                                      &led.max_brightness);
 160
 161                 ret = led_pwm_add(dev, priv, &led, child);
 162                 if (ret) {
 163                         of_node_put(child);
 164                         break;
 165                 }
 166         }
 167
 168         return ret;
 169 }
 170
 171 static int led_pwm_probe(struct platform_device *pdev)
 172 {
 173         struct led_pwm_platform_data *pdata = dev_get_platdata(&pdev->dev);
 174         struct led_pwm_priv *priv;
 175         int count, i;
 176         int ret = 0;
 177
 178         if (pdata)
 179                 count = pdata->num_leds;
 180         else
 181                 count = of_get_child_count(pdev->dev.of_node);
 182
 183         if (!count)
 184                 return -EINVAL;
 185
 186         priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
 187                             GFP_KERNEL);
 188         if (!priv)
 189                 return -ENOMEM;
 190
 191         if (pdata) {
 192                 for (i = 0; i < count; i++) {
 193                         ret = led_pwm_add(&pdev->dev, priv, &pdata->leds[i],
 194                                           NULL);
 195                         if (ret)
 196                                 break;
 197                 }
 198         } else {
 199                 ret = led_pwm_create_of(&pdev->dev, priv);
 200         }
 201
 202         if (ret) {
 203                 led_pwm_cleanup(priv);
 204                 return ret;
 205         }
 206
 207         platform_set_drvdata(pdev, priv);
 208
 209         return 0;
 210 }
 211
 212 static int led_pwm_remove(struct platform_device *pdev)
 213 {
 214         struct led_pwm_priv *priv = platform_get_drvdata(pdev);
 215
 216         led_pwm_cleanup(priv);
 217
 218         return 0;
 219 }
 220
 221 static const struct of_device_id of_pwm_leds_match[] = {
 222         { .compatible = "pwm-leds", },
 223         {},
 224 };
 225 MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 226
 227 static struct platform_driver led_pwm_driver = {
 228         .probe          = led_pwm_probe,
 229         .remove         = led_pwm_remove,
 230         .driver         = {
 231                 .name   = "leds_pwm",
 232                 .of_match_table = of_pwm_leds_match,
 233         },
 234 };
 235
 236 module_platform_driver(led_pwm_driver);
 237
 238 MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 239 MODULE_DESCRIPTION("PWM LED driver for PXA");
 240 MODULE_LICENSE("GPL");
 241 MODULE_ALIAS("platform:leds-pwm");