linux/drivers/leds/leds-dac124s085.c
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   1/*
   2 * Copyright 2008
   3 * Guennadi Liakhovetski, DENX Software Engineering, <lg@denx.de>
   4 *
   5 * This file is subject to the terms and conditions of version 2 of
   6 * the GNU General Public License.  See the file COPYING in the main
   7 * directory of this archive for more details.
   8 *
   9 * LED driver for the DAC124S085 SPI DAC
  10 */
  11
  12#include <linux/leds.h>
  13#include <linux/module.h>
  14#include <linux/mutex.h>
  15#include <linux/slab.h>
  16#include <linux/spinlock.h>
  17#include <linux/workqueue.h>
  18#include <linux/spi/spi.h>
  19
  20struct dac124s085_led {
  21        struct led_classdev     ldev;
  22        struct spi_device       *spi;
  23        int                     id;
  24        int                     brightness;
  25        char                    name[sizeof("dac124s085-3")];
  26
  27        struct mutex            mutex;
  28        struct work_struct      work;
  29        spinlock_t              lock;
  30};
  31
  32struct dac124s085 {
  33        struct dac124s085_led leds[4];
  34};
  35
  36#define REG_WRITE               (0 << 12)
  37#define REG_WRITE_UPDATE        (1 << 12)
  38#define ALL_WRITE_UPDATE        (2 << 12)
  39#define POWER_DOWN_OUTPUT       (3 << 12)
  40
  41static void dac124s085_led_work(struct work_struct *work)
  42{
  43        struct dac124s085_led *led = container_of(work, struct dac124s085_led,
  44                                                  work);
  45        u16 word;
  46
  47        mutex_lock(&led->mutex);
  48        word = cpu_to_le16(((led->id) << 14) | REG_WRITE_UPDATE |
  49                           (led->brightness & 0xfff));
  50        spi_write(led->spi, (const u8 *)&word, sizeof(word));
  51        mutex_unlock(&led->mutex);
  52}
  53
  54static void dac124s085_set_brightness(struct led_classdev *ldev,
  55                                      enum led_brightness brightness)
  56{
  57        struct dac124s085_led *led = container_of(ldev, struct dac124s085_led,
  58                                                  ldev);
  59
  60        spin_lock(&led->lock);
  61        led->brightness = brightness;
  62        schedule_work(&led->work);
  63        spin_unlock(&led->lock);
  64}
  65
  66static int dac124s085_probe(struct spi_device *spi)
  67{
  68        struct dac124s085       *dac;
  69        struct dac124s085_led   *led;
  70        int i, ret;
  71
  72        dac = devm_kzalloc(&spi->dev, sizeof(*dac), GFP_KERNEL);
  73        if (!dac)
  74                return -ENOMEM;
  75
  76        spi->bits_per_word = 16;
  77
  78        for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
  79                led             = dac->leds + i;
  80                led->id         = i;
  81                led->brightness = LED_OFF;
  82                led->spi        = spi;
  83                snprintf(led->name, sizeof(led->name), "dac124s085-%d", i);
  84                spin_lock_init(&led->lock);
  85                INIT_WORK(&led->work, dac124s085_led_work);
  86                mutex_init(&led->mutex);
  87                led->ldev.name = led->name;
  88                led->ldev.brightness = LED_OFF;
  89                led->ldev.max_brightness = 0xfff;
  90                led->ldev.brightness_set = dac124s085_set_brightness;
  91                ret = led_classdev_register(&spi->dev, &led->ldev);
  92                if (ret < 0)
  93                        goto eledcr;
  94        }
  95
  96        spi_set_drvdata(spi, dac);
  97
  98        return 0;
  99
 100eledcr:
 101        while (i--)
 102                led_classdev_unregister(&dac->leds[i].ldev);
 103
 104        spi_set_drvdata(spi, NULL);
 105        return ret;
 106}
 107
 108static int dac124s085_remove(struct spi_device *spi)
 109{
 110        struct dac124s085       *dac = spi_get_drvdata(spi);
 111        int i;
 112
 113        for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
 114                led_classdev_unregister(&dac->leds[i].ldev);
 115                cancel_work_sync(&dac->leds[i].work);
 116        }
 117
 118        spi_set_drvdata(spi, NULL);
 119
 120        return 0;
 121}
 122
 123static struct spi_driver dac124s085_driver = {
 124        .probe          = dac124s085_probe,
 125        .remove         = dac124s085_remove,
 126        .driver = {
 127                .name   = "dac124s085",
 128                .owner  = THIS_MODULE,
 129        },
 130};
 131
 132module_spi_driver(dac124s085_driver);
 133
 134MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
 135MODULE_DESCRIPTION("DAC124S085 LED driver");
 136MODULE_LICENSE("GPL v2");
 137MODULE_ALIAS("spi:dac124s085");
 138
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