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/of_device.h>
24#include <linux/of_address.h>
25#include <linux/platform_device.h>
26#include <linux/stat.h>
27#include <linux/slab.h>
28#include <linux/mfd/syscon.h>
29#include <linux/regmap.h>
30#include <linux/leds.h>
31
32/**
33 * struct syscon_led - state container for syscon based LEDs
34 * @cdev: LED class device for this LED
35 * @map: regmap to access the syscon device backing this LED
36 * @offset: the offset into the syscon regmap for the LED register
37 * @mask: the bit in the register corresponding to the LED
38 * @state: current state of the LED
39 */
40struct syscon_led {
41	struct led_classdev cdev;
42	struct regmap *map;
43	u32 offset;
44	u32 mask;
45	bool state;
46};
47
48static void syscon_led_set(struct led_classdev *led_cdev,
49	enum led_brightness value)
50{
51	struct syscon_led *sled =
52		container_of(led_cdev, struct syscon_led, cdev);
53	u32 val;
54	int ret;
55
56	if (value == LED_OFF) {
57		val = 0;
58		sled->state = false;
59	} else {
60		val = sled->mask;
61		sled->state = true;
62	}
63
64	ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
65	if (ret < 0)
66		dev_err(sled->cdev.dev, "error updating LED status\n");
67}
68
69static int __init syscon_leds_spawn(struct device_node *np,
70				    struct device *dev,
71				    struct regmap *map)
72{
73	struct device_node *child;
74	int ret;
75
76	for_each_available_child_of_node(np, child) {
77		struct syscon_led *sled;
78		const char *state;
79
80		/* Only check for register-bit-leds */
81		if (of_property_match_string(child, "compatible",
82					     "register-bit-led") < 0)
83			continue;
84
85		sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
86		if (!sled)
87			return -ENOMEM;
88
89		sled->map = map;
90
91		if (of_property_read_u32(child, "offset", &sled->offset))
92			return -EINVAL;
93		if (of_property_read_u32(child, "mask", &sled->mask))
94			return -EINVAL;
95		sled->cdev.name =
96			of_get_property(child, "label", NULL) ? : child->name;
97		sled->cdev.default_trigger =
98			of_get_property(child, "linux,default-trigger", NULL);
99
100		state = of_get_property(child, "default-state", NULL);
101		if (state) {
102			if (!strcmp(state, "keep")) {
103				u32 val;
104
105				ret = regmap_read(map, sled->offset, &val);
106				if (ret < 0)
107					return ret;
108				sled->state = !!(val & sled->mask);
109			} else if (!strcmp(state, "on")) {
110				sled->state = true;
111				ret = regmap_update_bits(map, sled->offset,
112							 sled->mask,
113							 sled->mask);
114				if (ret < 0)
115					return ret;
116			} else {
117				sled->state = false;
118				ret = regmap_update_bits(map, sled->offset,
119							 sled->mask, 0);
120				if (ret < 0)
121					return ret;
122			}
123		}
124		sled->cdev.brightness_set = syscon_led_set;
125
126		ret = led_classdev_register(dev, &sled->cdev);
127		if (ret < 0)
128			return ret;
129
130		dev_info(dev, "registered LED %s\n", sled->cdev.name);
131	}
132	return 0;
133}
134
135static int __init syscon_leds_init(void)
136{
137	struct device_node *np;
138
139	for_each_of_allnodes(np) {
140		struct platform_device *pdev;
141		struct regmap *map;
142		int ret;
143
144		if (!of_device_is_compatible(np, "syscon"))
145			continue;
146
147		map = syscon_node_to_regmap(np);
148		if (IS_ERR(map)) {
149			pr_err("error getting regmap for syscon LEDs\n");
150			continue;
151		}
152
153		/*
154		 * If the map is there, the device should be there, we allocate
155		 * memory on the syscon device's behalf here.
156		 */
157		pdev = of_find_device_by_node(np);
158		if (!pdev)
159			return -ENODEV;
160		ret = syscon_leds_spawn(np, &pdev->dev, map);
161		if (ret)
162			dev_err(&pdev->dev, "could not spawn syscon LEDs\n");
163	}
164
165	return 0;
166}
167device_initcall(syscon_leds_init);
168