linux/drivers/leds/leds-lt3593.c
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   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/init.h>
  21#include <linux/platform_device.h>
  22#include <linux/leds.h>
  23#include <linux/workqueue.h>
  24#include <linux/delay.h>
  25#include <linux/gpio.h>
  26#include <linux/slab.h>
  27#include <linux/module.h>
  28
  29struct lt3593_led_data {
  30        struct led_classdev cdev;
  31        unsigned gpio;
  32        struct work_struct work;
  33        u8 new_level;
  34};
  35
  36static void lt3593_led_work(struct work_struct *work)
  37{
  38        int pulses;
  39        struct lt3593_led_data *led_dat =
  40                container_of(work, struct lt3593_led_data, work);
  41
  42        /*
  43         * The LT3593 resets its internal current level register to the maximum
  44         * level on the first falling edge on the control pin. Each following
  45         * falling edge decreases the current level by 625uA. Up to 32 pulses
  46         * can be sent, so the maximum power reduction is 20mA.
  47         * After a timeout of 128us, the value is taken from the register and
  48         * applied is to the output driver.
  49         */
  50
  51        if (led_dat->new_level == 0) {
  52                gpio_set_value_cansleep(led_dat->gpio, 0);
  53                return;
  54        }
  55
  56        pulses = 32 - (led_dat->new_level * 32) / 255;
  57
  58        if (pulses == 0) {
  59                gpio_set_value_cansleep(led_dat->gpio, 0);
  60                mdelay(1);
  61                gpio_set_value_cansleep(led_dat->gpio, 1);
  62                return;
  63        }
  64
  65        gpio_set_value_cansleep(led_dat->gpio, 1);
  66
  67        while (pulses--) {
  68                gpio_set_value_cansleep(led_dat->gpio, 0);
  69                udelay(1);
  70                gpio_set_value_cansleep(led_dat->gpio, 1);
  71                udelay(1);
  72        }
  73}
  74
  75static void lt3593_led_set(struct led_classdev *led_cdev,
  76        enum led_brightness value)
  77{
  78        struct lt3593_led_data *led_dat =
  79                container_of(led_cdev, struct lt3593_led_data, cdev);
  80
  81        led_dat->new_level = value;
  82        schedule_work(&led_dat->work);
  83}
  84
  85static int create_lt3593_led(const struct gpio_led *template,
  86        struct lt3593_led_data *led_dat, struct device *parent)
  87{
  88        int ret, state;
  89
  90        /* skip leds on GPIOs that aren't available */
  91        if (!gpio_is_valid(template->gpio)) {
  92                dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
  93                                KBUILD_MODNAME, template->gpio, template->name);
  94                return 0;
  95        }
  96
  97        led_dat->cdev.name = template->name;
  98        led_dat->cdev.default_trigger = template->default_trigger;
  99        led_dat->gpio = template->gpio;
 100
 101        led_dat->cdev.brightness_set = lt3593_led_set;
 102
 103        state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
 104        led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
 105
 106        if (!template->retain_state_suspended)
 107                led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 108
 109        ret = devm_gpio_request_one(parent, template->gpio,
 110                                    GPIOF_DIR_OUT | state, template->name);
 111        if (ret < 0)
 112                return ret;
 113
 114        INIT_WORK(&led_dat->work, lt3593_led_work);
 115
 116        ret = led_classdev_register(parent, &led_dat->cdev);
 117        if (ret < 0)
 118                return ret;
 119
 120        dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d\n",
 121                KBUILD_MODNAME, template->name, template->gpio);
 122
 123        return 0;
 124}
 125
 126static void delete_lt3593_led(struct lt3593_led_data *led)
 127{
 128        if (!gpio_is_valid(led->gpio))
 129                return;
 130
 131        led_classdev_unregister(&led->cdev);
 132        cancel_work_sync(&led->work);
 133}
 134
 135static int lt3593_led_probe(struct platform_device *pdev)
 136{
 137        struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
 138        struct lt3593_led_data *leds_data;
 139        int i, ret = 0;
 140
 141        if (!pdata)
 142                return -EBUSY;
 143
 144        leds_data = devm_kzalloc(&pdev->dev,
 145                        sizeof(struct lt3593_led_data) * pdata->num_leds,
 146                        GFP_KERNEL);
 147        if (!leds_data)
 148                return -ENOMEM;
 149
 150        for (i = 0; i < pdata->num_leds; i++) {
 151                ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
 152                                      &pdev->dev);
 153                if (ret < 0)
 154                        goto err;
 155        }
 156
 157        platform_set_drvdata(pdev, leds_data);
 158
 159        return 0;
 160
 161err:
 162        for (i = i - 1; i >= 0; i--)
 163                delete_lt3593_led(&leds_data[i]);
 164
 165        return ret;
 166}
 167
 168static int lt3593_led_remove(struct platform_device *pdev)
 169{
 170        int i;
 171        struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
 172        struct lt3593_led_data *leds_data;
 173
 174        leds_data = platform_get_drvdata(pdev);
 175
 176        for (i = 0; i < pdata->num_leds; i++)
 177                delete_lt3593_led(&leds_data[i]);
 178
 179        return 0;
 180}
 181
 182static struct platform_driver lt3593_led_driver = {
 183        .probe          = lt3593_led_probe,
 184        .remove         = lt3593_led_remove,
 185        .driver         = {
 186                .name   = "leds-lt3593",
 187                .owner  = THIS_MODULE,
 188        },
 189};
 190
 191module_platform_driver(lt3593_led_driver);
 192
 193MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
 194MODULE_DESCRIPTION("LED driver for LT3593 controllers");
 195MODULE_LICENSE("GPL");
 196MODULE_ALIAS("platform:leds-lt3593");
 197
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