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#include <linux/workqueue.h>
  27
  28struct led_pwm_data {
  29        struct led_classdev     cdev;
  30        struct pwm_device       *pwm;
  31        struct work_struct      work;
  32        unsigned int            active_low;
  33        unsigned int            period;
  34        int                     duty;
  35        bool                    can_sleep;
  36};
  37
  38struct led_pwm_priv {
  39        int num_leds;
  40        struct led_pwm_data leds[0];
  41};
  42
  43static void __led_pwm_set(struct led_pwm_data *led_dat)
  44{
  45        int new_duty = led_dat->duty;
  46
  47        pwm_config(led_dat->pwm, new_duty, led_dat->period);
  48
  49        if (new_duty == 0)
  50                pwm_disable(led_dat->pwm);
  51        else
  52                pwm_enable(led_dat->pwm);
  53}
  54
  55static void led_pwm_work(struct work_struct *work)
  56{
  57        struct led_pwm_data *led_dat =
  58                container_of(work, struct led_pwm_data, work);
  59
  60        __led_pwm_set(led_dat);
  61}
  62
  63static void led_pwm_set(struct led_classdev *led_cdev,
  64        enum led_brightness brightness)
  65{
  66        struct led_pwm_data *led_dat =
  67                container_of(led_cdev, struct led_pwm_data, cdev);
  68        unsigned int max = led_dat->cdev.max_brightness;
  69        unsigned int period =  led_dat->period;
  70
  71        led_dat->duty = brightness * period / max;
  72
  73        if (led_dat->can_sleep)
  74                schedule_work(&led_dat->work);
  75        else
  76                __led_pwm_set(led_dat);
  77}
  78
  79static inline size_t sizeof_pwm_leds_priv(int num_leds)
  80{
  81        return sizeof(struct led_pwm_priv) +
  82                      (sizeof(struct led_pwm_data) * num_leds);
  83}
  84
  85static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
  86{
  87        struct device_node *node = pdev->dev.of_node;
  88        struct device_node *child;
  89        struct led_pwm_priv *priv;
  90        int count, ret;
  91
  92        /* count LEDs in this device, so we know how much to allocate */
  93        count = of_get_child_count(node);
  94        if (!count)
  95                return NULL;
  96
  97        priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
  98                            GFP_KERNEL);
  99        if (!priv)
 100                return NULL;
 101
 102        for_each_child_of_node(node, child) {
 103                struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
 104
 105                led_dat->cdev.name = of_get_property(child, "label",
 106                                                     NULL) ? : child->name;
 107
 108                led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
 109                if (IS_ERR(led_dat->pwm)) {
 110                        dev_err(&pdev->dev, "unable to request PWM for %s\n",
 111                                led_dat->cdev.name);
 112                        goto err;
 113                }
 114                /* Get the period from PWM core when n*/
 115                led_dat->period = pwm_get_period(led_dat->pwm);
 116
 117                led_dat->cdev.default_trigger = of_get_property(child,
 118                                                "linux,default-trigger", NULL);
 119                of_property_read_u32(child, "max-brightness",
 120                                     &led_dat->cdev.max_brightness);
 121
 122                led_dat->cdev.brightness_set = led_pwm_set;
 123                led_dat->cdev.brightness = LED_OFF;
 124                led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 125
 126                led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
 127                if (led_dat->can_sleep)
 128                        INIT_WORK(&led_dat->work, led_pwm_work);
 129
 130                ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 131                if (ret < 0) {
 132                        dev_err(&pdev->dev, "failed to register for %s\n",
 133                                led_dat->cdev.name);
 134                        of_node_put(child);
 135                        goto err;
 136                }
 137                priv->num_leds++;
 138        }
 139
 140        return priv;
 141err:
 142        while (priv->num_leds--)
 143                led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
 144
 145        return NULL;
 146}
 147
 148static int led_pwm_probe(struct platform_device *pdev)
 149{
 150        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 151        struct led_pwm_priv *priv;
 152        int i, ret = 0;
 153
 154        if (pdata && pdata->num_leds) {
 155                priv = devm_kzalloc(&pdev->dev,
 156                                    sizeof_pwm_leds_priv(pdata->num_leds),
 157                                    GFP_KERNEL);
 158                if (!priv)
 159                        return -ENOMEM;
 160
 161                for (i = 0; i < pdata->num_leds; i++) {
 162                        struct led_pwm *cur_led = &pdata->leds[i];
 163                        struct led_pwm_data *led_dat = &priv->leds[i];
 164
 165                        led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
 166                        if (IS_ERR(led_dat->pwm)) {
 167                                ret = PTR_ERR(led_dat->pwm);
 168                                dev_err(&pdev->dev,
 169                                        "unable to request PWM for %s\n",
 170                                        cur_led->name);
 171                                goto err;
 172                        }
 173
 174                        led_dat->cdev.name = cur_led->name;
 175                        led_dat->cdev.default_trigger = cur_led->default_trigger;
 176                        led_dat->active_low = cur_led->active_low;
 177                        led_dat->period = cur_led->pwm_period_ns;
 178                        led_dat->cdev.brightness_set = led_pwm_set;
 179                        led_dat->cdev.brightness = LED_OFF;
 180                        led_dat->cdev.max_brightness = cur_led->max_brightness;
 181                        led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 182
 183                        led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
 184                        if (led_dat->can_sleep)
 185                                INIT_WORK(&led_dat->work, led_pwm_work);
 186
 187                        ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
 188                        if (ret < 0)
 189                                goto err;
 190                }
 191                priv->num_leds = pdata->num_leds;
 192        } else {
 193                priv = led_pwm_create_of(pdev);
 194                if (!priv)
 195                        return -ENODEV;
 196        }
 197
 198        platform_set_drvdata(pdev, priv);
 199
 200        return 0;
 201
 202err:
 203        while (i--)
 204                led_classdev_unregister(&priv->leds[i].cdev);
 205
 206        return ret;
 207}
 208
 209static int led_pwm_remove(struct platform_device *pdev)
 210{
 211        struct led_pwm_priv *priv = platform_get_drvdata(pdev);
 212        int i;
 213
 214        for (i = 0; i < priv->num_leds; i++) {
 215                led_classdev_unregister(&priv->leds[i].cdev);
 216                if (priv->leds[i].can_sleep)
 217                        cancel_work_sync(&priv->leds[i].work);
 218        }
 219
 220        return 0;
 221}
 222
 223static const struct of_device_id of_pwm_leds_match[] = {
 224        { .compatible = "pwm-leds", },
 225        {},
 226};
 227MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
 228
 229static struct platform_driver led_pwm_driver = {
 230        .probe          = led_pwm_probe,
 231        .remove         = led_pwm_remove,
 232        .driver         = {
 233                .name   = "leds_pwm",
 234                .owner  = THIS_MODULE,
 235                .of_match_table = of_match_ptr(of_pwm_leds_match),
 236        },
 237};
 238
 239module_platform_driver(led_pwm_driver);
 240
 241MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 242MODULE_DESCRIPTION("PWM LED driver for PXA");
 243MODULE_LICENSE("GPL");
 244MODULE_ALIAS("platform:leds-pwm");
 245
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