LXR linux/drivers/leds/leds-dac124s085.c

   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/gfp.h>
  13#include <linux/leds.h>
  14#include <linux/module.h>
  15#include <linux/mutex.h>
  16#include <linux/slab.h>
  17#include <linux/spinlock.h>
  18#include <linux/workqueue.h>
  19#include <linux/spi/spi.h>
  20
  21struct dac124s085_led {
  22        struct led_classdev     ldev;
  23        struct spi_device       *spi;
  24        int                     id;
  25        int                     brightness;
  26        char                    name[sizeof("dac124s085-3")];
  27
  28        struct mutex            mutex;
  29        struct work_struct      work;
  30        spinlock_t              lock;
  31};
  32
  33struct dac124s085 {
  34        struct dac124s085_led leds[4];
  35};
  36
  37#define REG_WRITE               (0 << 12)
  38#define REG_WRITE_UPDATE        (1 << 12)
  39#define ALL_WRITE_UPDATE        (2 << 12)
  40#define POWER_DOWN_OUTPUT       (3 << 12)
  41
  42static void dac124s085_led_work(struct work_struct *work)
  43{
  44        struct dac124s085_led *led = container_of(work, struct dac124s085_led,
  45                                                  work);
  46        u16 word;
  47
  48        mutex_lock(&led->mutex);
  49        word = cpu_to_le16(((led->id) << 14) | REG_WRITE_UPDATE |
  50                           (led->brightness & 0xfff));
  51        spi_write(led->spi, (const u8 *)&word, sizeof(word));
  52        mutex_unlock(&led->mutex);
  53}
  54
  55static void dac124s085_set_brightness(struct led_classdev *ldev,
  56                                      enum led_brightness brightness)
  57{
  58        struct dac124s085_led *led = container_of(ldev, struct dac124s085_led,
  59                                                  ldev);
  60
  61        spin_lock(&led->lock);
  62        led->brightness = brightness;
  63        schedule_work(&led->work);
  64        spin_unlock(&led->lock);
  65}
  66
  67static int dac124s085_probe(struct spi_device *spi)
  68{
  69        struct dac124s085       *dac;
  70        struct dac124s085_led   *led;
  71        int i, ret;
  72
  73        dac = kzalloc(sizeof(*dac), GFP_KERNEL);
  74        if (!dac)
  75                return -ENOMEM;
  76
  77        spi->bits_per_word = 16;
  78
  79        for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
  80                led             = dac->leds + i;
  81                led->id         = i;
  82                led->brightness = LED_OFF;
  83                led->spi        = spi;
  84                snprintf(led->name, sizeof(led->name), "dac124s085-%d", i);
  85                spin_lock_init(&led->lock);
  86                INIT_WORK(&led->work, dac124s085_led_work);
  87                mutex_init(&led->mutex);
  88                led->ldev.name = led->name;
  89                led->ldev.brightness = LED_OFF;
  90                led->ldev.max_brightness = 0xfff;
  91                led->ldev.brightness_set = dac124s085_set_brightness;
  92                ret = led_classdev_register(&spi->dev, &led->ldev);
  93                if (ret < 0)
  94                        goto eledcr;
  95        }
  96
  97        spi_set_drvdata(spi, dac);
  98
  99        return 0;
 100
 101eledcr:
 102        while (i--)
 103                led_classdev_unregister(&dac->leds[i].ldev);
 104
 105        spi_set_drvdata(spi, NULL);
 106        kfree(dac);
 107        return ret;
 108}
 109
 110static int dac124s085_remove(struct spi_device *spi)
 111{
 112        struct dac124s085       *dac = spi_get_drvdata(spi);
 113        int i;
 114
 115        for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
 116                led_classdev_unregister(&dac->leds[i].ldev);
 117                cancel_work_sync(&dac->leds[i].work);
 118        }
 119
 120        spi_set_drvdata(spi, NULL);
 121        kfree(dac);
 122
 123        return 0;
 124}
 125
 126static struct spi_driver dac124s085_driver = {
 127        .probe          = dac124s085_probe,
 128        .remove         = dac124s085_remove,
 129        .driver = {
 130                .name   = "dac124s085",
 131                .owner  = THIS_MODULE,
 132        },
 133};
 134
 135static int __init dac124s085_leds_init(void)
 136{
 137        return spi_register_driver(&dac124s085_driver);
 138}
 139
 140static void __exit dac124s085_leds_exit(void)
 141{
 142        spi_unregister_driver(&dac124s085_driver);
 143}
 144
 145module_init(dac124s085_leds_init);
 146module_exit(dac124s085_leds_exit);
 147
 148MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
 149MODULE_DESCRIPTION("DAC124S085 LED driver");
 150MODULE_LICENSE("GPL v2");
 151MODULE_ALIAS("spi:dac124s085");
 152