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 = 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 
100 eledcr:
101 	while (i--)
102 		led_classdev_unregister(&dac->leds[i].ldev);
103 
104 	return ret;
105 }
106 
107 static 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 
120 static 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 
129 module_spi_driver(dac124s085_driver);
130 
131 MODULE_AUTHOR("Guennadi Liakhovetski <lg@denx.de>");
132 MODULE_DESCRIPTION("DAC124S085 LED driver");
133 MODULE_LICENSE("GPL v2");
134 MODULE_ALIAS("spi:dac124s085");
135