linux/drivers/leds/leds-pwm.c
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   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
  27struct led_pwm_data {
  28        struct led_classdev     cdev;
  29        struct pwm_device       *pwm;
  30        unsigned int            active_low;
  31        unsigned int            period;
  32};
  33
  34struct led_pwm_priv {
  35        int num_leds;
  36        struct led_pwm_data leds[0];
  37};
  38
  39static 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
  56static 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
  62static 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;
 114err:
 115        while (priv->num_leds--)
 116                led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
 117
 118        return NULL;
 119}
 120
 121static 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
 171err:
 172        while (i--)
 173                led_classdev_unregister(&priv->leds[i].cdev);
 174
 175        return ret;
 176}
 177
 178static 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
 189static const struct of_device_id of_pwm_leds_match[] = {
 190        { .compatible = "pwm-leds", },
 191        {},
 192};
 193MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 194
 195static 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
 205module_platform_driver(led_pwm_driver);
 206
 207MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 208MODULE_DESCRIPTION("PWM LED driver for PXA");
 209MODULE_LICENSE("GPL");
 210MODULE_ALIAS("platform:leds-pwm");
 211
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