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	return ret;
105}
106
107static int dac124s085_remove(struct spi_device *spi)
108{
109	struct dac124s085	*dac = spi_get_drvdata(spi);
110	int i;
111
112	for (i = 0; i < ARRAY_SIZE(dac->leds); i++) {
113		led_classdev_unregister(&dac->leds[i].ldev);
114		cancel_work_sync(&dac->leds[i].work);
115	}
116
117	return 0;
118}
119
120static struct spi_driver dac124s085_driver = {
121	.probe		= dac124s085_probe,
122	.remove		= dac124s085_remove,
123	.driver = {
124		.name	= "dac124s085",
125		.owner	= THIS_MODULE,
126	},
127};
128
129module_spi_driver(dac124s085_driver);
130
131MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
132MODULE_DESCRIPTION("DAC124S085 LED driver");
133MODULE_LICENSE("GPL v2");
134MODULE_ALIAS("spi:dac124s085");
135