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/spinlock.h>
  17 #include <linux/workqueue.h>
  18 #include <linux/spi/spi.h>
  19
  20 struct 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
  32 struct 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
  41 static 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
  54 static 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
  66 static int dac124s085_probe(struct spi_device *spi)
  67 {
  68         struct dac124s085       *dac;
  69         struct dac124s085_led   *led;
  70         int i, ret;
  71
  72         dac = kzalloc(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
 100 eledcr:
 101         while (i--)
 102                 led_classdev_unregister(&dac->leds[i].ldev);
 103
 104         spi_set_drvdata(spi, NULL);
 105         kfree(dac);
 106         return ret;
 107 }
 108
 109 static int dac124s085_remove(struct spi_device *spi)
 110 {
 111         struct dac124s085       *dac = spi_get_drvdata(spi);
 112         int i;
 113
 114         for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
 115                 led_classdev_unregister(&dac->leds[i].ldev);
 116                 cancel_work_sync(&dac->leds[i].work);
 117         }
 118
 119         spi_set_drvdata(spi, NULL);
 120         kfree(dac);
 121
 122         return 0;
 123 }
 124
 125 static struct spi_driver dac124s085_driver = {
 126         .probe          = dac124s085_probe,
 127         .remove         = dac124s085_remove,
 128         .driver = {
 129                 .name   = "dac124s085",
 130                 .owner  = THIS_MODULE,
 131         },
 132 };
 133
 134 module_spi_driver(dac124s085_driver);
 135
 136 MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
 137 MODULE_DESCRIPTION("DAC124S085 LED driver");
 138 MODULE_LICENSE("GPL v2");
 139 MODULE_ALIAS("spi:dac124s085");