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
  21 struct 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
  33 struct 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
  42 static 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
  55 static 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
  67 static 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
 101 eledcr:
 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
 110 static 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
 126 static 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
 135 static int __init dac124s085_leds_init(void)
 136 {
 137         return spi_register_driver(&dac124s085_driver);
 138 }
 139
 140 static void __exit dac124s085_leds_exit(void)
 141 {
 142         spi_unregister_driver(&dac124s085_driver);
 143 }
 144
 145 module_init(dac124s085_leds_init);
 146 module_exit(dac124s085_leds_exit);
 147
 148 MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
 149 MODULE_DESCRIPTION("DAC124S085 LED driver");
 150 MODULE_LICENSE("GPL v2");