1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic Syscon LEDs Driver
4 *
5 * Copyright (c) 2014, Linaro Limited
6 * Author: Linus Walleij <linus.walleij@linaro.org>
7 */
8#include <linux/io.h>
9#include <linux/init.h>
10#include <linux/of.h>
11#include <linux/platform_device.h>
12#include <linux/stat.h>
13#include <linux/slab.h>
14#include <linux/mfd/syscon.h>
15#include <linux/regmap.h>
16#include <linux/leds.h>
17
18/**
19 * struct syscon_led - state container for syscon based LEDs
20 * @cdev: LED class device for this LED
21 * @map: regmap to access the syscon device backing this LED
22 * @offset: the offset into the syscon regmap for the LED register
23 * @mask: the bit in the register corresponding to the LED
24 * @state: current state of the LED
25 */
26struct syscon_led {
27	struct led_classdev cdev;
28	struct regmap *map;
29	u32 offset;
30	u32 mask;
31	bool state;
32};
33
34static void syscon_led_set(struct led_classdev *led_cdev,
35	enum led_brightness value)
36{
37	struct syscon_led *sled =
38		container_of(led_cdev, struct syscon_led, cdev);
39	u32 val;
40	int ret;
41
42	if (value == LED_OFF) {
43		val = 0;
44		sled->state = false;
45	} else {
46		val = sled->mask;
47		sled->state = true;
48	}
49
50	ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
51	if (ret < 0)
52		dev_err(sled->cdev.dev, "error updating LED status\n");
53}
54
55static int syscon_led_probe(struct platform_device *pdev)
56{
57	struct led_init_data init_data = {};
58	struct device *dev = &pdev->dev;
59	struct device_node *np = dev_of_node(dev);
60	struct device *parent;
61	struct regmap *map;
62	struct syscon_led *sled;
63	enum led_default_state state;
64	u32 value;
65	int ret;
66
67	parent = dev->parent;
68	if (!parent) {
69		dev_err(dev, "no parent for syscon LED\n");
70		return -ENODEV;
71	}
72	map = syscon_node_to_regmap(dev_of_node(parent));
73	if (IS_ERR(map)) {
74		dev_err(dev, "no regmap for syscon LED parent\n");
75		return PTR_ERR(map);
76	}
77
78	sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
79	if (!sled)
80		return -ENOMEM;
81
82	sled->map = map;
83
84	if (of_property_read_u32(np, "offset", &sled->offset))
85		return -EINVAL;
86	if (of_property_read_u32(np, "mask", &sled->mask))
87		return -EINVAL;
88
89	init_data.fwnode = of_fwnode_handle(np);
90
91	state = led_init_default_state_get(init_data.fwnode);
92	switch (state) {
93	case LEDS_DEFSTATE_ON:
94		ret = regmap_update_bits(map, sled->offset, sled->mask, sled->mask);
95		if (ret < 0)
96			return ret;
97		sled->state = true;
98		break;
99	case LEDS_DEFSTATE_KEEP:
100		ret = regmap_read(map, sled->offset, &value);
101		if (ret < 0)
102			return ret;
103		sled->state = !!(value & sled->mask);
104		break;
105	default:
106		ret = regmap_update_bits(map, sled->offset, sled->mask, 0);
107		if (ret < 0)
108			return ret;
109		sled->state = false;
110	}
111	sled->cdev.brightness_set = syscon_led_set;
112
113	ret = devm_led_classdev_register_ext(dev, &sled->cdev, &init_data);
114	if (ret < 0)
115		return ret;
116
117	platform_set_drvdata(pdev, sled);
118	dev_info(dev, "registered LED %s\n", sled->cdev.name);
119
120	return 0;
121}
122
123static const struct of_device_id of_syscon_leds_match[] = {
124	{ .compatible = "register-bit-led", },
125	{},
126};
127
128static struct platform_driver syscon_led_driver = {
129	.probe		= syscon_led_probe,
130	.driver		= {
131		.name	= "leds-syscon",
132		.of_match_table = of_syscon_leds_match,
133		.suppress_bind_attrs = true,
134	},
135};
136builtin_platform_driver(syscon_led_driver);
137