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a8dd18fe DM |
1 | /* |
2 | * LEDs driver for LT3593 controllers | |
3 | * | |
4 | * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf | |
5 | * | |
6 | * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de> | |
7 | * | |
8 | * Based on leds-gpio.c, | |
9 | * | |
10 | * Copyright (C) 2007 8D Technologies inc. | |
11 | * Raphael Assenat <raph@8d.com> | |
12 | * Copyright (C) 2008 Freescale Semiconductor, Inc. | |
13 | * | |
14 | * This program is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU General Public License version 2 as | |
16 | * published by the Free Software Foundation. | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/platform_device.h> | |
22 | #include <linux/leds.h> | |
23 | #include <linux/workqueue.h> | |
24 | #include <linux/delay.h> | |
25 | #include <linux/gpio.h> | |
5a0e3ad6 | 26 | #include <linux/slab.h> |
a8dd18fe DM |
27 | |
28 | struct lt3593_led_data { | |
29 | struct led_classdev cdev; | |
30 | unsigned gpio; | |
31 | struct work_struct work; | |
32 | u8 new_level; | |
33 | }; | |
34 | ||
35 | static void lt3593_led_work(struct work_struct *work) | |
36 | { | |
37 | int pulses; | |
38 | struct lt3593_led_data *led_dat = | |
39 | container_of(work, struct lt3593_led_data, work); | |
40 | ||
41 | /* | |
42 | * The LT3593 resets its internal current level register to the maximum | |
43 | * level on the first falling edge on the control pin. Each following | |
44 | * falling edge decreases the current level by 625uA. Up to 32 pulses | |
45 | * can be sent, so the maximum power reduction is 20mA. | |
46 | * After a timeout of 128us, the value is taken from the register and | |
47 | * applied is to the output driver. | |
48 | */ | |
49 | ||
50 | if (led_dat->new_level == 0) { | |
51 | gpio_set_value_cansleep(led_dat->gpio, 0); | |
52 | return; | |
53 | } | |
54 | ||
55 | pulses = 32 - (led_dat->new_level * 32) / 255; | |
56 | ||
57 | if (pulses == 0) { | |
58 | gpio_set_value_cansleep(led_dat->gpio, 0); | |
59 | mdelay(1); | |
60 | gpio_set_value_cansleep(led_dat->gpio, 1); | |
61 | return; | |
62 | } | |
63 | ||
64 | gpio_set_value_cansleep(led_dat->gpio, 1); | |
65 | ||
66 | while (pulses--) { | |
67 | gpio_set_value_cansleep(led_dat->gpio, 0); | |
68 | udelay(1); | |
69 | gpio_set_value_cansleep(led_dat->gpio, 1); | |
70 | udelay(1); | |
71 | } | |
72 | } | |
73 | ||
74 | static void lt3593_led_set(struct led_classdev *led_cdev, | |
75 | enum led_brightness value) | |
76 | { | |
77 | struct lt3593_led_data *led_dat = | |
78 | container_of(led_cdev, struct lt3593_led_data, cdev); | |
79 | ||
80 | led_dat->new_level = value; | |
81 | schedule_work(&led_dat->work); | |
82 | } | |
83 | ||
84 | static int __devinit create_lt3593_led(const struct gpio_led *template, | |
85 | struct lt3593_led_data *led_dat, struct device *parent) | |
86 | { | |
87 | int ret, state; | |
88 | ||
89 | /* skip leds on GPIOs that aren't available */ | |
90 | if (!gpio_is_valid(template->gpio)) { | |
91 | printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n", | |
92 | KBUILD_MODNAME, template->gpio, template->name); | |
93 | return 0; | |
94 | } | |
95 | ||
96 | ret = gpio_request(template->gpio, template->name); | |
97 | if (ret < 0) | |
98 | return ret; | |
99 | ||
100 | led_dat->cdev.name = template->name; | |
101 | led_dat->cdev.default_trigger = template->default_trigger; | |
102 | led_dat->gpio = template->gpio; | |
103 | ||
104 | led_dat->cdev.brightness_set = lt3593_led_set; | |
105 | ||
106 | state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); | |
107 | led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; | |
108 | ||
109 | if (!template->retain_state_suspended) | |
110 | led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME; | |
111 | ||
112 | ret = gpio_direction_output(led_dat->gpio, state); | |
113 | if (ret < 0) | |
114 | goto err; | |
115 | ||
116 | INIT_WORK(&led_dat->work, lt3593_led_work); | |
117 | ||
118 | ret = led_classdev_register(parent, &led_dat->cdev); | |
119 | if (ret < 0) | |
120 | goto err; | |
121 | ||
122 | printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n", | |
123 | KBUILD_MODNAME, template->name, template->gpio); | |
124 | ||
125 | return 0; | |
126 | ||
127 | err: | |
128 | gpio_free(led_dat->gpio); | |
129 | return ret; | |
130 | } | |
131 | ||
132 | static void delete_lt3593_led(struct lt3593_led_data *led) | |
133 | { | |
134 | if (!gpio_is_valid(led->gpio)) | |
135 | return; | |
136 | ||
137 | led_classdev_unregister(&led->cdev); | |
138 | cancel_work_sync(&led->work); | |
139 | gpio_free(led->gpio); | |
140 | } | |
141 | ||
142 | static int __devinit lt3593_led_probe(struct platform_device *pdev) | |
143 | { | |
144 | struct gpio_led_platform_data *pdata = pdev->dev.platform_data; | |
145 | struct lt3593_led_data *leds_data; | |
146 | int i, ret = 0; | |
147 | ||
148 | if (!pdata) | |
149 | return -EBUSY; | |
150 | ||
151 | leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds, | |
152 | GFP_KERNEL); | |
153 | if (!leds_data) | |
154 | return -ENOMEM; | |
155 | ||
156 | for (i = 0; i < pdata->num_leds; i++) { | |
157 | ret = create_lt3593_led(&pdata->leds[i], &leds_data[i], | |
158 | &pdev->dev); | |
159 | if (ret < 0) | |
160 | goto err; | |
161 | } | |
162 | ||
163 | platform_set_drvdata(pdev, leds_data); | |
164 | ||
165 | return 0; | |
166 | ||
167 | err: | |
168 | for (i = i - 1; i >= 0; i--) | |
169 | delete_lt3593_led(&leds_data[i]); | |
170 | ||
171 | kfree(leds_data); | |
172 | ||
173 | return ret; | |
174 | } | |
175 | ||
176 | static int __devexit lt3593_led_remove(struct platform_device *pdev) | |
177 | { | |
178 | int i; | |
179 | struct gpio_led_platform_data *pdata = pdev->dev.platform_data; | |
180 | struct lt3593_led_data *leds_data; | |
181 | ||
182 | leds_data = platform_get_drvdata(pdev); | |
183 | ||
184 | for (i = 0; i < pdata->num_leds; i++) | |
185 | delete_lt3593_led(&leds_data[i]); | |
186 | ||
187 | kfree(leds_data); | |
188 | ||
189 | return 0; | |
190 | } | |
191 | ||
192 | static struct platform_driver lt3593_led_driver = { | |
193 | .probe = lt3593_led_probe, | |
194 | .remove = __devexit_p(lt3593_led_remove), | |
195 | .driver = { | |
196 | .name = "leds-lt3593", | |
197 | .owner = THIS_MODULE, | |
198 | }, | |
199 | }; | |
200 | ||
201 | MODULE_ALIAS("platform:leds-lt3593"); | |
202 | ||
203 | static int __init lt3593_led_init(void) | |
204 | { | |
205 | return platform_driver_register(<3593_led_driver); | |
206 | } | |
207 | ||
208 | static void __exit lt3593_led_exit(void) | |
209 | { | |
210 | platform_driver_unregister(<3593_led_driver); | |
211 | } | |
212 | ||
213 | module_init(lt3593_led_init); | |
214 | module_exit(lt3593_led_exit); | |
215 | ||
216 | MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>"); | |
217 | MODULE_DESCRIPTION("LED driver for LT3593 controllers"); | |
218 | MODULE_LICENSE("GPL"); |