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, "reg", &sled->offset) &&
85	    of_property_read_u32(np, "offset", &sled->offset))
86		return -EINVAL;
87	if (of_property_read_u32(np, "mask", &sled->mask))
88		return -EINVAL;
89
90	init_data.fwnode = of_fwnode_handle(np);
91
92	state = led_init_default_state_get(init_data.fwnode);
93	switch (state) {
94	case LEDS_DEFSTATE_ON:
95		ret = regmap_update_bits(map, sled->offset, sled->mask, sled->mask);
96		if (ret < 0)
97			return ret;
98		sled->state = true;
99		break;
100	case LEDS_DEFSTATE_KEEP:
101		ret = regmap_read(map, sled->offset, &value);
102		if (ret < 0)
103			return ret;
104		sled->state = !!(value & sled->mask);
105		break;
106	default:
107		ret = regmap_update_bits(map, sled->offset, sled->mask, 0);
108		if (ret < 0)
109			return ret;
110		sled->state = false;
111	}
112	sled->cdev.brightness_set = syscon_led_set;
113
114	ret = devm_led_classdev_register_ext(dev, &sled->cdev, &init_data);
115	if (ret < 0)
116		return ret;
117
118	platform_set_drvdata(pdev, sled);
119	dev_info(dev, "registered LED %s\n", sled->cdev.name);
120
121	return 0;
122}
123
124static const struct of_device_id of_syscon_leds_match[] = {
125	{ .compatible = "register-bit-led", },
126	{},
127};
128
129static struct platform_driver syscon_led_driver = {
130	.probe		= syscon_led_probe,
131	.driver		= {
132		.name	= "leds-syscon",
133		.of_match_table = of_syscon_leds_match,
134		.suppress_bind_attrs = true,
135	},
136};
137builtin_platform_driver(syscon_led_driver);
138