Root/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
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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