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 * This driver provides system reboot functionality for APM X-Gene SoC.
23 * For system shutdown, this is board specify. If a board designer
24 * implements GPIO shutdown, use the gpio-poweroff.c driver.
25 */
26#include <linux/io.h>
27#include <linux/of_device.h>
28#include <linux/of_address.h>
29#include <linux/platform_device.h>
30#include <linux/stat.h>
31#include <linux/slab.h>
32#include <linux/mfd/syscon.h>
33#include <linux/regmap.h>
34#include <linux/leds.h>
35
36/**
37 * struct syscon_led - state container for syscon based LEDs
38 * @cdev: LED class device for this LED
39 * @map: regmap to access the syscon device backing this LED
40 * @offset: the offset into the syscon regmap for the LED register
41 * @mask: the bit in the register corresponding to the LED
42 * @state: current state of the LED
43 */
44struct syscon_led {
45	struct led_classdev cdev;
46	struct regmap *map;
47	u32 offset;
48	u32 mask;
49	bool state;
50};
51
52static void syscon_led_set(struct led_classdev *led_cdev,
53	enum led_brightness value)
54{
55	struct syscon_led *sled =
56		container_of(led_cdev, struct syscon_led, cdev);
57	u32 val;
58	int ret;
59
60	if (value == LED_OFF) {
61		val = 0;
62		sled->state = false;
63	} else {
64		val = sled->mask;
65		sled->state = true;
66	}
67
68	ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
69	if (ret < 0)
70		dev_err(sled->cdev.dev, "error updating LED status\n");
71}
72
73static const struct of_device_id syscon_match[] = {
74	{ .compatible = "syscon", },
75	{},
76};
77
78static int __init syscon_leds_init(void)
79{
80	const struct of_device_id *devid;
81	struct device_node *np;
82	struct device_node *child;
83	struct regmap *map;
84	struct platform_device *pdev;
85	struct device *dev;
86	int ret;
87
88	np = of_find_matching_node_and_match(NULL, syscon_match,
89					     &devid);
90	if (!np)
91		return -ENODEV;
92
93	map = syscon_node_to_regmap(np);
94	if (IS_ERR(map))
95		return PTR_ERR(map);
96
97	/*
98	 * If the map is there, the device should be there, we allocate
99	 * memory on the syscon device's behalf here.
100	 */
101	pdev = of_find_device_by_node(np);
102	if (!pdev)
103		return -ENODEV;
104	dev = &pdev->dev;
105
106	for_each_available_child_of_node(np, child) {
107		struct syscon_led *sled;
108		const char *state;
109
110		/* Only check for register-bit-leds */
111		if (of_property_match_string(child, "compatible",
112					     "register-bit-led") < 0)
113			continue;
114
115		sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
116		if (!sled)
117			return -ENOMEM;
118
119		sled->map = map;
120
121		if (of_property_read_u32(child, "offset", &sled->offset))
122			return -EINVAL;
123		if (of_property_read_u32(child, "mask", &sled->mask))
124			return -EINVAL;
125		sled->cdev.name =
126			of_get_property(child, "label", NULL) ? : child->name;
127		sled->cdev.default_trigger =
128			of_get_property(child, "linux,default-trigger", NULL);
129
130		state = of_get_property(child, "default-state", NULL);
131		if (state) {
132			if (!strcmp(state, "keep")) {
133				u32 val;
134
135				ret = regmap_read(map, sled->offset, &val);
136				if (ret < 0)
137					return ret;
138				sled->state = !!(val & sled->mask);
139			} else if (!strcmp(state, "on")) {
140				sled->state = true;
141				ret = regmap_update_bits(map, sled->offset,
142							 sled->mask,
143							 sled->mask);
144				if (ret < 0)
145					return ret;
146			} else {
147				sled->state = false;
148				ret = regmap_update_bits(map, sled->offset,
149							 sled->mask, 0);
150				if (ret < 0)
151					return ret;
152			}
153
154		}
155		sled->cdev.brightness_set = syscon_led_set;
156
157		ret = led_classdev_register(dev, &sled->cdev);
158		if (ret < 0)
159			return ret;
160
161		dev_info(dev, "registered LED %s\n", sled->cdev.name);
162	}
163
164       return 0;
165}
166device_initcall(syscon_leds_init);
167