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");
151 MODULE_ALIAS("spi:dac124s085");
152