LXR linux/drivers/leds/leds-lt3593.c

   1/*
   2 * LEDs driver for LT3593 controllers
   3 *
   4 * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
   5 *
   6 * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
   7 *
   8 * Based on leds-gpio.c,
   9 *
  10 *   Copyright (C) 2007 8D Technologies inc.
  11 *   Raphael Assenat <raph@8d.com>
  12 *   Copyright (C) 2008 Freescale Semiconductor, Inc.
  13 *
  14 * This program is free software; you can redistribute it and/or modify
  15 * it under the terms of the GNU General Public License version 2 as
  16 * published by the Free Software Foundation.
  17 */
  18
  19#include <linux/kernel.h>
  20#include <linux/platform_device.h>
  21#include <linux/leds.h>
  22#include <linux/delay.h>
  23#include <linux/gpio.h>
  24#include <linux/slab.h>
  25#include <linux/module.h>
  26
  27struct lt3593_led_data {
  28        struct led_classdev cdev;
  29        unsigned gpio;
  30};
  31
  32static int lt3593_led_set(struct led_classdev *led_cdev,
  33                           enum led_brightness value)
  34{
  35        struct lt3593_led_data *led_dat =
  36                container_of(led_cdev, struct lt3593_led_data, cdev);
  37        int pulses;
  38
  39        /*
  40         * The LT3593 resets its internal current level register to the maximum
  41         * level on the first falling edge on the control pin. Each following
  42         * falling edge decreases the current level by 625uA. Up to 32 pulses
  43         * can be sent, so the maximum power reduction is 20mA.
  44         * After a timeout of 128us, the value is taken from the register and
  45         * applied is to the output driver.
  46         */
  47
  48        if (value == 0) {
  49                gpio_set_value_cansleep(led_dat->gpio, 0);
  50                return 0;
  51        }
  52
  53        pulses = 32 - (value * 32) / 255;
  54
  55        if (pulses == 0) {
  56                gpio_set_value_cansleep(led_dat->gpio, 0);
  57                mdelay(1);
  58                gpio_set_value_cansleep(led_dat->gpio, 1);
  59                return 0;
  60        }
  61
  62        gpio_set_value_cansleep(led_dat->gpio, 1);
  63
  64        while (pulses--) {
  65                gpio_set_value_cansleep(led_dat->gpio, 0);
  66                udelay(1);
  67                gpio_set_value_cansleep(led_dat->gpio, 1);
  68                udelay(1);
  69        }
  70
  71        return 0;
  72}
  73
  74static int create_lt3593_led(const struct gpio_led *template,
  75        struct lt3593_led_data *led_dat, struct device *parent)
  76{
  77        int ret, state;
  78
  79        /* skip leds on GPIOs that aren't available */
  80        if (!gpio_is_valid(template->gpio)) {
  81                dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
  82                                KBUILD_MODNAME, template->gpio, template->name);
  83                return 0;
  84        }
  85
  86        led_dat->cdev.name = template->name;
  87        led_dat->cdev.default_trigger = template->default_trigger;
  88        led_dat->gpio = template->gpio;
  89
  90        led_dat->cdev.brightness_set_blocking = lt3593_led_set;
  91
  92        state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
  93        led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
  94
  95        if (!template->retain_state_suspended)
  96                led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
  97
  98        ret = devm_gpio_request_one(parent, template->gpio, state ?
  99                                    GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
 100                                    template->name);
 101        if (ret < 0)
 102                return ret;
 103
 104        ret = led_classdev_register(parent, &led_dat->cdev);
 105        if (ret < 0)
 106                return ret;
 107
 108        dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n",
 109                KBUILD_MODNAME, template->name, template->gpio);
 110
 111        return 0;
 112}
 113
 114static void delete_lt3593_led(struct lt3593_led_data *led)
 115{
 116        if (!gpio_is_valid(led->gpio))
 117                return;
 118
 119        led_classdev_unregister(&led->cdev);
 120}
 121
 122static int lt3593_led_probe(struct platform_device *pdev)
 123{
 124        struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
 125        struct lt3593_led_data *leds_data;
 126        int i, ret = 0;
 127
 128        if (!pdata)
 129                return -EBUSY;
 130
 131        leds_data = devm_kzalloc(&pdev->dev,
 132                        sizeof(struct lt3593_led_data) * pdata->num_leds,
 133                        GFP_KERNEL);
 134        if (!leds_data)
 135                return -ENOMEM;
 136
 137        for (i = 0; i < pdata->num_leds; i++) {
 138                ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
 139                                      &pdev->dev);
 140                if (ret < 0)
 141                        goto err;
 142        }
 143
 144        platform_set_drvdata(pdev, leds_data);
 145
 146        return 0;
 147
 148err:
 149        for (i = i - 1; i >= 0; i--)
 150                delete_lt3593_led(&leds_data[i]);
 151
 152        return ret;
 153}
 154
 155static int lt3593_led_remove(struct platform_device *pdev)
 156{
 157        int i;
 158        struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
 159        struct lt3593_led_data *leds_data;
 160
 161        leds_data = platform_get_drvdata(pdev);
 162
 163        for (i = 0; i < pdata->num_leds; i++)
 164                delete_lt3593_led(&leds_data[i]);
 165
 166        return 0;
 167}
 168
 169static struct platform_driver lt3593_led_driver = {
 170        .probe          = lt3593_led_probe,
 171        .remove         = lt3593_led_remove,
 172        .driver         = {
 173                .name   = "leds-lt3593",
 174        },
 175};
 176
 177module_platform_driver(lt3593_led_driver);
 178
 179MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
 180MODULE_DESCRIPTION("LED driver for LT3593 controllers");
 181MODULE_LICENSE("GPL");
 182MODULE_ALIAS("platform:leds-lt3593");
 183