1/*
2 * Generic Syscon LEDs Driver
3 *
4 * Copyright (c) 2014, Linaro Limited
5 * Author: Linus Walleij <linus.walleij@linaro.org>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
20 * MA 02111-1307 USA
21 */
22#include <linux/io.h>
23#include <linux/module.h>
24#include <linux/of_device.h>
25#include <linux/of_address.h>
26#include <linux/platform_device.h>
27#include <linux/stat.h>
28#include <linux/slab.h>
29#include <linux/mfd/syscon.h>
30#include <linux/regmap.h>
31#include <linux/leds.h>
32
33/**
34 * struct syscon_led - state container for syscon based LEDs
35 * @cdev: LED class device for this LED
36 * @map: regmap to access the syscon device backing this LED
37 * @offset: the offset into the syscon regmap for the LED register
38 * @mask: the bit in the register corresponding to the LED
39 * @state: current state of the LED
40 */
41struct syscon_led {
42	struct led_classdev cdev;
43	struct regmap *map;
44	u32 offset;
45	u32 mask;
46	bool state;
47};
48
49static void syscon_led_set(struct led_classdev *led_cdev,
50	enum led_brightness value)
51{
52	struct syscon_led *sled =
53		container_of(led_cdev, struct syscon_led, cdev);
54	u32 val;
55	int ret;
56
57	if (value == LED_OFF) {
58		val = 0;
59		sled->state = false;
60	} else {
61		val = sled->mask;
62		sled->state = true;
63	}
64
65	ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
66	if (ret < 0)
67		dev_err(sled->cdev.dev, "error updating LED status\n");
68}
69
70static int syscon_led_probe(struct platform_device *pdev)
71{
72	struct device *dev = &pdev->dev;
73	struct device_node *np = dev->of_node;
74	struct device *parent;
75	struct regmap *map;
76	struct syscon_led *sled;
77	const char *state;
78	int ret;
79
80	parent = dev->parent;
81	if (!parent) {
82		dev_err(dev, "no parent for syscon LED\n");
83		return -ENODEV;
84	}
85	map = syscon_node_to_regmap(parent->of_node);
86	if (IS_ERR(map)) {
87		dev_err(dev, "no regmap for syscon LED parent\n");
88		return PTR_ERR(map);
89	}
90
91	sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
92	if (!sled)
93		return -ENOMEM;
94
95	sled->map = map;
96
97	if (of_property_read_u32(np, "offset", &sled->offset))
98		return -EINVAL;
99	if (of_property_read_u32(np, "mask", &sled->mask))
100		return -EINVAL;
101	sled->cdev.name =
102		of_get_property(np, "label", NULL) ? : np->name;
103	sled->cdev.default_trigger =
104		of_get_property(np, "linux,default-trigger", NULL);
105
106	state = of_get_property(np, "default-state", NULL);
107	if (state) {
108		if (!strcmp(state, "keep")) {
109			u32 val;
110
111			ret = regmap_read(map, sled->offset, &val);
112			if (ret < 0)
113				return ret;
114			sled->state = !!(val & sled->mask);
115		} else if (!strcmp(state, "on")) {
116			sled->state = true;
117			ret = regmap_update_bits(map, sled->offset,
118						 sled->mask,
119						 sled->mask);
120			if (ret < 0)
121				return ret;
122		} else {
123			sled->state = false;
124			ret = regmap_update_bits(map, sled->offset,
125						 sled->mask, 0);
126			if (ret < 0)
127				return ret;
128		}
129	}
130	sled->cdev.brightness_set = syscon_led_set;
131
132	ret = led_classdev_register(dev, &sled->cdev);
133	if (ret < 0)
134		return ret;
135
136	platform_set_drvdata(pdev, sled);
137	dev_info(dev, "registered LED %s\n", sled->cdev.name);
138
139	return 0;
140}
141
142static int syscon_led_remove(struct platform_device *pdev)
143{
144	struct syscon_led *sled = platform_get_drvdata(pdev);
145
146	led_classdev_unregister(&sled->cdev);
147	/* Turn it off */
148	regmap_update_bits(sled->map, sled->offset, sled->mask, 0);
149	return 0;
150}
151
152static const struct of_device_id of_syscon_leds_match[] = {
153	{ .compatible = "register-bit-led", },
154	{},
155};
156
157MODULE_DEVICE_TABLE(of, of_syscon_leds_match);
158
159static struct platform_driver syscon_led_driver = {
160	.probe		= syscon_led_probe,
161	.remove		= syscon_led_remove,
162	.driver		= {
163		.name	= "leds-syscon",
164		.of_match_table = of_syscon_leds_match,
165	},
166};
167module_platform_driver(syscon_led_driver);
168