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/leds.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/slab.h>
  16 #include <linux/spi/spi.h>
  17
  18 struct dac124s085_led {
  19         struct led_classdev     ldev;
  20         struct spi_device       *spi;
  21         int                     id;
  22         char                    name[sizeof("dac124s085-3")];
  23
  24         struct mutex            mutex;
  25 };
  26
  27 struct dac124s085 {
  28         struct dac124s085_led leds[4];
  29 };
  30
  31 #define REG_WRITE               (0 << 12)
  32 #define REG_WRITE_UPDATE        (1 << 12)
  33 #define ALL_WRITE_UPDATE        (2 << 12)
  34 #define POWER_DOWN_OUTPUT       (3 << 12)
  35
  36 static int dac124s085_set_brightness(struct led_classdev *ldev,
  37                                       enum led_brightness brightness)
  38 {
  39         struct dac124s085_led *led = container_of(ldev, struct dac124s085_led,
  40                                                   ldev);
  41         u16 word;
  42         int ret;
  43
  44         mutex_lock(&led->mutex);
  45         word = cpu_to_le16(((led->id) << 14) | REG_WRITE_UPDATE |
  46                            (brightness & 0xfff));
  47         ret = spi_write(led->spi, (const u8 *)&word, sizeof(word));
  48         mutex_unlock(&led->mutex);
  49
  50         return ret;
  51 }
  52
  53 static int dac124s085_probe(struct spi_device *spi)
  54 {
  55         struct dac124s085       *dac;
  56         struct dac124s085_led   *led;
  57         int i, ret;
  58
  59         dac = devm_kzalloc(&spi->dev, sizeof(*dac), GFP_KERNEL);
  60         if (!dac)
  61                 return -ENOMEM;
  62
  63         spi->bits_per_word = 16;
  64
  65         for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
  66                 led             = dac->leds + i;
  67                 led->id         = i;
  68                 led->spi        = spi;
  69                 snprintf(led->name, sizeof(led->name), "dac124s085-%d", i);
  70                 mutex_init(&led->mutex);
  71                 led->ldev.name = led->name;
  72                 led->ldev.brightness = LED_OFF;
  73                 led->ldev.max_brightness = 0xfff;
  74                 led->ldev.brightness_set_blocking = dac124s085_set_brightness;
  75                 ret = led_classdev_register(&spi->dev, &led->ldev);
  76                 if (ret < 0)
  77                         goto eledcr;
  78         }
  79
  80         spi_set_drvdata(spi, dac);
  81
  82         return 0;
  83
  84 eledcr:
  85         while (i--)
  86                 led_classdev_unregister(&dac->leds[i].ldev);
  87
  88         return ret;
  89 }
  90
  91 static int dac124s085_remove(struct spi_device *spi)
  92 {
  93         struct dac124s085       *dac = spi_get_drvdata(spi);
  94         int i;
  95
  96         for (i = 0; i < ARRAY_SIZE(dac->leds); i++)
  97                 led_classdev_unregister(&dac->leds[i].ldev);
  98
  99         return 0;
 100 }
 101
 102 static struct spi_driver dac124s085_driver = {
 103         .probe          = dac124s085_probe,
 104         .remove         = dac124s085_remove,
 105         .driver = {
 106                 .name   = "dac124s085",
 107         },
 108 };
 109
 110 module_spi_driver(dac124s085_driver);
 111
 112 MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
 113 MODULE_DESCRIPTION("DAC124S085 LED driver");
 114 MODULE_LICENSE("GPL v2");
 115 MODULE_ALIAS("spi:dac124s085");