LXR linux/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/fb.h>
  20#include <linux/leds.h>
  21#include <linux/err.h>
  22#include <linux/pwm.h>
  23#include <linux/leds_pwm.h>
  24
  25struct led_pwm_data {
  26        struct led_classdev     cdev;
  27        struct pwm_device       *pwm;
  28        unsigned int            active_low;
  29        unsigned int            period;
  30};
  31
  32static void led_pwm_set(struct led_classdev *led_cdev,
  33        enum led_brightness brightness)
  34{
  35        struct led_pwm_data *led_dat =
  36                container_of(led_cdev, struct led_pwm_data, cdev);
  37        unsigned int max = led_dat->cdev.max_brightness;
  38        unsigned int period =  led_dat->period;
  39
  40        if (brightness == 0) {
  41                pwm_config(led_dat->pwm, 0, period);
  42                pwm_disable(led_dat->pwm);
  43        } else {
  44                pwm_config(led_dat->pwm, brightness * period / max, period);
  45                pwm_enable(led_dat->pwm);
  46        }
  47}
  48
  49static int led_pwm_probe(struct platform_device *pdev)
  50{
  51        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
  52        struct led_pwm *cur_led;
  53        struct led_pwm_data *leds_data, *led_dat;
  54        int i, ret = 0;
  55
  56        if (!pdata)
  57                return -EBUSY;
  58
  59        leds_data = kzalloc(sizeof(struct led_pwm_data) * pdata->num_leds,
  60                                GFP_KERNEL);
  61        if (!leds_data)
  62                return -ENOMEM;
  63
  64        for (i = 0; i < pdata->num_leds; i++) {
  65                cur_led = &pdata->leds[i];
  66                led_dat = &leds_data[i];
  67
  68                led_dat->pwm = pwm_request(cur_led->pwm_id,
  69                                cur_led->name);
  70                if (IS_ERR(led_dat->pwm)) {
  71                        dev_err(&pdev->dev, "unable to request PWM %d\n",
  72                                        cur_led->pwm_id);
  73                        goto err;
  74                }
  75
  76                led_dat->cdev.name = cur_led->name;
  77                led_dat->cdev.default_trigger = cur_led->default_trigger;
  78                led_dat->active_low = cur_led->active_low;
  79                led_dat->period = cur_led->pwm_period_ns;
  80                led_dat->cdev.brightness_set = led_pwm_set;
  81                led_dat->cdev.brightness = LED_OFF;
  82                led_dat->cdev.max_brightness = cur_led->max_brightness;
  83                led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  84
  85                ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
  86                if (ret < 0) {
  87                        pwm_free(led_dat->pwm);
  88                        goto err;
  89                }
  90        }
  91
  92        platform_set_drvdata(pdev, leds_data);
  93
  94        return 0;
  95
  96err:
  97        if (i > 0) {
  98                for (i = i - 1; i >= 0; i--) {
  99                        led_classdev_unregister(&leds_data[i].cdev);
 100                        pwm_free(leds_data[i].pwm);
 101                }
 102        }
 103
 104        kfree(leds_data);
 105
 106        return ret;
 107}
 108
 109static int __devexit led_pwm_remove(struct platform_device *pdev)
 110{
 111        int i;
 112        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
 113        struct led_pwm_data *leds_data;
 114
 115        leds_data = platform_get_drvdata(pdev);
 116
 117        for (i = 0; i < pdata->num_leds; i++) {
 118                led_classdev_unregister(&leds_data[i].cdev);
 119                pwm_free(leds_data[i].pwm);
 120        }
 121
 122        kfree(leds_data);
 123
 124        return 0;
 125}
 126
 127static struct platform_driver led_pwm_driver = {
 128        .probe          = led_pwm_probe,
 129        .remove         = __devexit_p(led_pwm_remove),
 130        .driver         = {
 131                .name   = "leds_pwm",
 132                .owner  = THIS_MODULE,
 133        },
 134};
 135
 136static int __init led_pwm_init(void)
 137{
 138        return platform_driver_register(&led_pwm_driver);
 139}
 140
 141static void __exit led_pwm_exit(void)
 142{
 143        platform_driver_unregister(&led_pwm_driver);
 144}
 145
 146module_init(led_pwm_init);
 147module_exit(led_pwm_exit);
 148
 149MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
 150MODULE_DESCRIPTION("PWM LED driver for PXA");
 151MODULE_LICENSE("GPL");
 152MODULE_ALIAS("platform:leds-pwm");
 153