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/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
  26struct led_pwm_data {
  27        struct led_classdev     cdev;
  28        struct pwm_device       *pwm;
  29        unsigned int            active_low;
  30        unsigned int            period;
  31};
  32
  33static void led_pwm_set(struct led_classdev *led_cdev,
  34        enum led_brightness brightness)
  35{
  36        struct led_pwm_data *led_dat =
  37                container_of(led_cdev, struct led_pwm_data, cdev);
  38        unsigned int max = led_dat->cdev.max_brightness;
  39        unsigned int period =  led_dat->period;
  40
  41        if (brightness == 0) {
  42                pwm_config(led_dat->pwm, 0, period);
  43                pwm_disable(led_dat->pwm);
  44        } else {
  45                pwm_config(led_dat->pwm, brightness * period / max, period);
  46                pwm_enable(led_dat->pwm);
  47        }
  48}
  49
  50static int led_pwm_probe(struct platform_device *pdev)
  51{
  52        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
  53        struct led_pwm *cur_led;
  54        struct led_pwm_data *leds_data, *led_dat;
  55        int i, ret = 0;
  56
  57        if (!pdata)
  58                return -EBUSY;
  59
  60        leds_data = devm_kzalloc(&pdev->dev,
  61                        sizeof(struct led_pwm_data) * pdata->num_leds,
  62                                GFP_KERNEL);
  63        if (!leds_data)
  64                return -ENOMEM;
  65
  66        for (i = 0; i < pdata->num_leds; i++) {
  67                cur_led = &pdata->leds[i];
  68                led_dat = &leds_data[i];
  69
  70                led_dat->pwm = pwm_request(cur_led->pwm_id,
  71                                cur_led->name);
  72                if (IS_ERR(led_dat->pwm)) {
  73                        ret = PTR_ERR(led_dat->pwm);
  74                        dev_err(&pdev->dev, "unable to request PWM %d\n",
  75                                        cur_led->pwm_id);
  76                        goto err;
  77                }
  78
  79                led_dat->cdev.name = cur_led->name;
  80                led_dat->cdev.default_trigger = cur_led->default_trigger;
  81                led_dat->active_low = cur_led->active_low;
  82                led_dat->period = cur_led->pwm_period_ns;
  83                led_dat->cdev.brightness_set = led_pwm_set;
  84                led_dat->cdev.brightness = LED_OFF;
  85                led_dat->cdev.max_brightness = cur_led->max_brightness;
  86                led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  87
  88                ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
  89                if (ret < 0) {
  90                        pwm_free(led_dat->pwm);
  91                        goto err;
  92                }
  93        }
  94
  95        platform_set_drvdata(pdev, leds_data);
  96
  97        return 0;
  98
  99err:
 100        if (i > 0) {
 101                for (i = i - 1; i >= 0; i--) {
 102                        led_classdev_unregister(&leds_data[i].cdev);
 103                        pwm_free(leds_data[i].pwm);
 104                }
 105        }
 106
 107        return ret;
 108}
 109
 110static int led_pwm_remove(struct platform_device *pdev)
 111{
 112        int i;
 113        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 114        struct led_pwm_data *leds_data;
 115
 116        leds_data = platform_get_drvdata(pdev);
 117
 118        for (i = 0; i < pdata->num_leds; i++) {
 119                led_classdev_unregister(&leds_data[i].cdev);
 120                pwm_free(leds_data[i].pwm);
 121        }
 122
 123        return 0;
 124}
 125
 126static struct platform_driver led_pwm_driver = {
 127        .probe          = led_pwm_probe,
 128        .remove         = led_pwm_remove,
 129        .driver         = {
 130                .name   = "leds_pwm",
 131                .owner  = THIS_MODULE,
 132        },
 133};
 134
 135module_platform_driver(led_pwm_driver);
 136
 137MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 138MODULE_DESCRIPTION("PWM LED driver for PXA");
 139MODULE_LICENSE("GPL");
 140MODULE_ALIAS("platform:leds-pwm");
 141
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