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_device.h>
 11#include <linux/of_address.h>
 12#include <linux/platform_device.h>
 13#include <linux/stat.h>
 14#include <linux/slab.h>
 15#include <linux/mfd/syscon.h>
 16#include <linux/regmap.h>
 17#include <linux/leds.h>
 18
 19/**
 20 * struct syscon_led - state container for syscon based LEDs
 21 * @cdev: LED class device for this LED
 22 * @map: regmap to access the syscon device backing this LED
 23 * @offset: the offset into the syscon regmap for the LED register
 24 * @mask: the bit in the register corresponding to the LED
 25 * @state: current state of the LED
 26 */
 27struct syscon_led {
 28	struct led_classdev cdev;
 29	struct regmap *map;
 30	u32 offset;
 31	u32 mask;
 32	bool state;
 33};
 34
 35static void syscon_led_set(struct led_classdev *led_cdev,
 36	enum led_brightness value)
 37{
 38	struct syscon_led *sled =
 39		container_of(led_cdev, struct syscon_led, cdev);
 40	u32 val;
 41	int ret;
 42
 43	if (value == LED_OFF) {
 44		val = 0;
 45		sled->state = false;
 46	} else {
 47		val = sled->mask;
 48		sled->state = true;
 49	}
 50
 51	ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
 52	if (ret < 0)
 53		dev_err(sled->cdev.dev, "error updating LED status\n");
 54}
 55
 56static int syscon_led_probe(struct platform_device *pdev)
 57{
 58	struct device *dev = &pdev->dev;
 59	struct device_node *np = dev->of_node;
 60	struct device *parent;
 61	struct regmap *map;
 62	struct syscon_led *sled;
 63	const char *state;
 64	int ret;
 65
 66	parent = dev->parent;
 67	if (!parent) {
 68		dev_err(dev, "no parent for syscon LED\n");
 69		return -ENODEV;
 70	}
 71	map = syscon_node_to_regmap(parent->of_node);
 72	if (IS_ERR(map)) {
 73		dev_err(dev, "no regmap for syscon LED parent\n");
 74		return PTR_ERR(map);
 75	}
 76
 77	sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
 78	if (!sled)
 79		return -ENOMEM;
 80
 81	sled->map = map;
 82
 83	if (of_property_read_u32(np, "offset", &sled->offset))
 84		return -EINVAL;
 85	if (of_property_read_u32(np, "mask", &sled->mask))
 86		return -EINVAL;
 87	sled->cdev.name =
 88		of_get_property(np, "label", NULL) ? : np->name;
 89	sled->cdev.default_trigger =
 90		of_get_property(np, "linux,default-trigger", NULL);
 91
 92	state = of_get_property(np, "default-state", NULL);
 93	if (state) {
 94		if (!strcmp(state, "keep")) {
 95			u32 val;
 96
 97			ret = regmap_read(map, sled->offset, &val);
 98			if (ret < 0)
 99				return ret;
100			sled->state = !!(val & sled->mask);
101		} else if (!strcmp(state, "on")) {
102			sled->state = true;
103			ret = regmap_update_bits(map, sled->offset,
104						 sled->mask,
105						 sled->mask);
106			if (ret < 0)
107				return ret;
108		} else {
109			sled->state = false;
110			ret = regmap_update_bits(map, sled->offset,
111						 sled->mask, 0);
112			if (ret < 0)
113				return ret;
114		}
115	}
116	sled->cdev.brightness_set = syscon_led_set;
117
118	ret = devm_led_classdev_register(dev, &sled->cdev);
119	if (ret < 0)
120		return ret;
121
122	platform_set_drvdata(pdev, sled);
123	dev_info(dev, "registered LED %s\n", sled->cdev.name);
124
125	return 0;
126}
127
128static const struct of_device_id of_syscon_leds_match[] = {
129	{ .compatible = "register-bit-led", },
130	{},
131};
132
133static struct platform_driver syscon_led_driver = {
134	.probe		= syscon_led_probe,
135	.driver		= {
136		.name	= "leds-syscon",
137		.of_match_table = of_syscon_leds_match,
138		.suppress_bind_attrs = true,
139	},
140};
141builtin_platform_driver(syscon_led_driver);