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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>
26#include <linux/slab.h>
27#include <linux/module.h>
28
29struct lt3593_led_data {
30 struct led_classdev cdev;
31 unsigned gpio;
32 struct work_struct work;
33 u8 new_level;
34};
35
36static void lt3593_led_work(struct work_struct *work)
37{
38 int pulses;
39 struct lt3593_led_data *led_dat =
40 container_of(work, struct lt3593_led_data, work);
41
42 /*
43 * The LT3593 resets its internal current level register to the maximum
44 * level on the first falling edge on the control pin. Each following
45 * falling edge decreases the current level by 625uA. Up to 32 pulses
46 * can be sent, so the maximum power reduction is 20mA.
47 * After a timeout of 128us, the value is taken from the register and
48 * applied is to the output driver.
49 */
50
51 if (led_dat->new_level == 0) {
52 gpio_set_value_cansleep(led_dat->gpio, 0);
53 return;
54 }
55
56 pulses = 32 - (led_dat->new_level * 32) / 255;
57
58 if (pulses == 0) {
59 gpio_set_value_cansleep(led_dat->gpio, 0);
60 mdelay(1);
61 gpio_set_value_cansleep(led_dat->gpio, 1);
62 return;
63 }
64
65 gpio_set_value_cansleep(led_dat->gpio, 1);
66
67 while (pulses--) {
68 gpio_set_value_cansleep(led_dat->gpio, 0);
69 udelay(1);
70 gpio_set_value_cansleep(led_dat->gpio, 1);
71 udelay(1);
72 }
73}
74
75static void lt3593_led_set(struct led_classdev *led_cdev,
76 enum led_brightness value)
77{
78 struct lt3593_led_data *led_dat =
79 container_of(led_cdev, struct lt3593_led_data, cdev);
80
81 led_dat->new_level = value;
82 schedule_work(&led_dat->work);
83}
84
85static int __devinit create_lt3593_led(const struct gpio_led *template,
86 struct lt3593_led_data *led_dat, struct device *parent)
87{
88 int ret, state;
89
90 /* skip leds on GPIOs that aren't available */
91 if (!gpio_is_valid(template->gpio)) {
92 printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
93 KBUILD_MODNAME, template->gpio, template->name);
94 return 0;
95 }
96
97 ret = gpio_request(template->gpio, template->name);
98 if (ret < 0)
99 return ret;
100
101 led_dat->cdev.name = template->name;
102 led_dat->cdev.default_trigger = template->default_trigger;
103 led_dat->gpio = template->gpio;
104
105 led_dat->cdev.brightness_set = lt3593_led_set;
106
107 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
108 led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
109
110 if (!template->retain_state_suspended)
111 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
112
113 ret = gpio_direction_output(led_dat->gpio, state);
114 if (ret < 0)
115 goto err;
116
117 INIT_WORK(&led_dat->work, lt3593_led_work);
118
119 ret = led_classdev_register(parent, &led_dat->cdev);
120 if (ret < 0)
121 goto err;
122
123 printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",
124 KBUILD_MODNAME, template->name, template->gpio);
125
126 return 0;
127
128err:
129 gpio_free(led_dat->gpio);
130 return ret;
131}
132
133static void delete_lt3593_led(struct lt3593_led_data *led)
134{
135 if (!gpio_is_valid(led->gpio))
136 return;
137
138 led_classdev_unregister(&led->cdev);
139 cancel_work_sync(&led->work);
140 gpio_free(led->gpio);
141}
142
143static int __devinit lt3593_led_probe(struct platform_device *pdev)
144{
145 struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
146 struct lt3593_led_data *leds_data;
147 int i, ret = 0;
148
149 if (!pdata)
150 return -EBUSY;
151
152 leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds,
153 GFP_KERNEL);
154 if (!leds_data)
155 return -ENOMEM;
156
157 for (i = 0; i < pdata->num_leds; i++) {
158 ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
159 &pdev->dev);
160 if (ret < 0)
161 goto err;
162 }
163
164 platform_set_drvdata(pdev, leds_data);
165
166 return 0;
167
168err:
169 for (i = i - 1; i >= 0; i--)
170 delete_lt3593_led(&leds_data[i]);
171
172 kfree(leds_data);
173
174 return ret;
175}
176
177static int __devexit lt3593_led_remove(struct platform_device *pdev)
178{
179 int i;
180 struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
181 struct lt3593_led_data *leds_data;
182
183 leds_data = platform_get_drvdata(pdev);
184
185 for (i = 0; i < pdata->num_leds; i++)
186 delete_lt3593_led(&leds_data[i]);
187
188 kfree(leds_data);
189
190 return 0;
191}
192
193static struct platform_driver lt3593_led_driver = {
194 .probe = lt3593_led_probe,
195 .remove = __devexit_p(lt3593_led_remove),
196 .driver = {
197 .name = "leds-lt3593",
198 .owner = THIS_MODULE,
199 },
200};
201
202module_platform_driver(lt3593_led_driver);
203
204MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
205MODULE_DESCRIPTION("LED driver for LT3593 controllers");
206MODULE_LICENSE("GPL");
207MODULE_ALIAS("platform:leds-lt3593");
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
3
4#include <linux/kernel.h>
5#include <linux/platform_device.h>
6#include <linux/leds.h>
7#include <linux/delay.h>
8#include <linux/gpio/consumer.h>
9#include <linux/slab.h>
10#include <linux/mod_devicetable.h>
11#include <linux/module.h>
12#include <linux/property.h>
13
14#define LED_LT3593_NAME "lt3593"
15
16struct lt3593_led_data {
17 struct led_classdev cdev;
18 struct gpio_desc *gpiod;
19};
20
21static int lt3593_led_set(struct led_classdev *led_cdev,
22 enum led_brightness value)
23{
24 struct lt3593_led_data *led_dat =
25 container_of(led_cdev, struct lt3593_led_data, cdev);
26 int pulses;
27
28 /*
29 * The LT3593 resets its internal current level register to the maximum
30 * level on the first falling edge on the control pin. Each following
31 * falling edge decreases the current level by 625uA. Up to 32 pulses
32 * can be sent, so the maximum power reduction is 20mA.
33 * After a timeout of 128us, the value is taken from the register and
34 * applied is to the output driver.
35 */
36
37 if (value == 0) {
38 gpiod_set_value_cansleep(led_dat->gpiod, 0);
39 return 0;
40 }
41
42 pulses = 32 - (value * 32) / 255;
43
44 if (pulses == 0) {
45 gpiod_set_value_cansleep(led_dat->gpiod, 0);
46 mdelay(1);
47 gpiod_set_value_cansleep(led_dat->gpiod, 1);
48 return 0;
49 }
50
51 gpiod_set_value_cansleep(led_dat->gpiod, 1);
52
53 while (pulses--) {
54 gpiod_set_value_cansleep(led_dat->gpiod, 0);
55 udelay(1);
56 gpiod_set_value_cansleep(led_dat->gpiod, 1);
57 udelay(1);
58 }
59
60 return 0;
61}
62
63static int lt3593_led_probe(struct platform_device *pdev)
64{
65 struct device *dev = &pdev->dev;
66 struct lt3593_led_data *led_data;
67 struct fwnode_handle *child;
68 int ret, state = LEDS_GPIO_DEFSTATE_OFF;
69 struct led_init_data init_data = {};
70 const char *tmp;
71
72 led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
73 if (!led_data)
74 return -ENOMEM;
75
76 if (device_get_child_node_count(dev) != 1) {
77 dev_err(dev, "Device must have exactly one LED sub-node.");
78 return -EINVAL;
79 }
80
81 led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
82 if (IS_ERR(led_data->gpiod))
83 return PTR_ERR(led_data->gpiod);
84
85 child = device_get_next_child_node(dev, NULL);
86
87 if (!fwnode_property_read_string(child, "default-state", &tmp)) {
88 if (!strcmp(tmp, "on"))
89 state = LEDS_GPIO_DEFSTATE_ON;
90 }
91
92 led_data->cdev.brightness_set_blocking = lt3593_led_set;
93 led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
94
95 init_data.fwnode = child;
96 init_data.devicename = LED_LT3593_NAME;
97 init_data.default_label = ":";
98
99 ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
100 fwnode_handle_put(child);
101 if (ret < 0)
102 return ret;
103
104 platform_set_drvdata(pdev, led_data);
105
106 return 0;
107}
108
109static const struct of_device_id of_lt3593_leds_match[] = {
110 { .compatible = "lltc,lt3593", },
111 {},
112};
113MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
114
115static struct platform_driver lt3593_led_driver = {
116 .probe = lt3593_led_probe,
117 .driver = {
118 .name = "leds-lt3593",
119 .of_match_table = of_lt3593_leds_match,
120 },
121};
122
123module_platform_driver(lt3593_led_driver);
124
125MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
126MODULE_DESCRIPTION("LED driver for LT3593 controllers");
127MODULE_LICENSE("GPL v2");
128MODULE_ALIAS("platform:leds-lt3593");