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/init.h>
 24#include <linux/of_device.h>
 25#include <linux/of_address.h>
 26#include <linux/platform_device.h>
 27#include <linux/stat.h>
 28#include <linux/slab.h>
 29#include <linux/mfd/syscon.h>
 30#include <linux/regmap.h>
 31#include <linux/leds.h>
 32
 33/**
 34 * struct syscon_led - state container for syscon based LEDs
 35 * @cdev: LED class device for this LED
 36 * @map: regmap to access the syscon device backing this LED
 37 * @offset: the offset into the syscon regmap for the LED register
 38 * @mask: the bit in the register corresponding to the LED
 39 * @state: current state of the LED
 40 */
 41struct syscon_led {
 42	struct led_classdev cdev;
 43	struct regmap *map;
 44	u32 offset;
 45	u32 mask;
 46	bool state;
 47};
 48
 49static void syscon_led_set(struct led_classdev *led_cdev,
 50	enum led_brightness value)
 51{
 52	struct syscon_led *sled =
 53		container_of(led_cdev, struct syscon_led, cdev);
 54	u32 val;
 55	int ret;
 56
 57	if (value == LED_OFF) {
 58		val = 0;
 59		sled->state = false;
 60	} else {
 61		val = sled->mask;
 62		sled->state = true;
 63	}
 64
 65	ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
 66	if (ret < 0)
 67		dev_err(sled->cdev.dev, "error updating LED status\n");
 68}
 69
 70static int syscon_led_probe(struct platform_device *pdev)
 71{
 72	struct device *dev = &pdev->dev;
 73	struct device_node *np = dev->of_node;
 74	struct device *parent;
 75	struct regmap *map;
 76	struct syscon_led *sled;
 77	const char *state;
 78	int ret;
 79
 80	parent = dev->parent;
 81	if (!parent) {
 82		dev_err(dev, "no parent for syscon LED\n");
 83		return -ENODEV;
 84	}
 85	map = syscon_node_to_regmap(parent->of_node);
 86	if (IS_ERR(map)) {
 87		dev_err(dev, "no regmap for syscon LED parent\n");
 88		return PTR_ERR(map);
 89	}
 90
 91	sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
 92	if (!sled)
 93		return -ENOMEM;
 94
 95	sled->map = map;
 96
 97	if (of_property_read_u32(np, "offset", &sled->offset))
 98		return -EINVAL;
 99	if (of_property_read_u32(np, "mask", &sled->mask))
100		return -EINVAL;
101	sled->cdev.name =
102		of_get_property(np, "label", NULL) ? : np->name;
103	sled->cdev.default_trigger =
104		of_get_property(np, "linux,default-trigger", NULL);
105
106	state = of_get_property(np, "default-state", NULL);
107	if (state) {
108		if (!strcmp(state, "keep")) {
109			u32 val;
110
111			ret = regmap_read(map, sled->offset, &val);
112			if (ret < 0)
113				return ret;
114			sled->state = !!(val & sled->mask);
115		} else if (!strcmp(state, "on")) {
116			sled->state = true;
117			ret = regmap_update_bits(map, sled->offset,
118						 sled->mask,
119						 sled->mask);
120			if (ret < 0)
121				return ret;
122		} else {
123			sled->state = false;
124			ret = regmap_update_bits(map, sled->offset,
125						 sled->mask, 0);
126			if (ret < 0)
127				return ret;
128		}
129	}
130	sled->cdev.brightness_set = syscon_led_set;
131
132	ret = led_classdev_register(dev, &sled->cdev);
133	if (ret < 0)
134		return ret;
135
136	platform_set_drvdata(pdev, sled);
137	dev_info(dev, "registered LED %s\n", sled->cdev.name);
138
139	return 0;
140}
141
142static const struct of_device_id of_syscon_leds_match[] = {
143	{ .compatible = "register-bit-led", },
144	{},
145};
146
147static struct platform_driver syscon_led_driver = {
148	.probe		= syscon_led_probe,
149	.driver		= {
150		.name	= "leds-syscon",
151		.of_match_table = of_syscon_leds_match,
152		.suppress_bind_attrs = true,
153	},
154};
155builtin_platform_driver(syscon_led_driver);