max8925_bl.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Backlight driver for Maxim MAX8925
  4 *
  5 * Copyright (C) 2009 Marvell International Ltd.
  6 *      Haojian Zhuang <haojian.zhuang@marvell.com>
  7 */
  8
  9#include <linux/init.h>
 10#include <linux/kernel.h>
 11#include <linux/platform_device.h>
 12#include <linux/i2c.h>
 13#include <linux/backlight.h>
 14#include <linux/mfd/max8925.h>
 15#include <linux/slab.h>
 16#include <linux/module.h>
 17
 18#define MAX_BRIGHTNESS		(0xff)
 19#define MIN_BRIGHTNESS		(0)
 20
 21#define LWX_FREQ(x)		(((x - 601) / 100) & 0x7)
 22
 23struct max8925_backlight_data {
 24	struct max8925_chip	*chip;
 25
 26	int	current_brightness;
 27	int	reg_mode_cntl;
 28	int	reg_cntl;
 29};
 30
 31static int max8925_backlight_set(struct backlight_device *bl, int brightness)
 32{
 33	struct max8925_backlight_data *data = bl_get_data(bl);
 34	struct max8925_chip *chip = data->chip;
 35	unsigned char value;
 36	int ret;
 37
 38	if (brightness > MAX_BRIGHTNESS)
 39		value = MAX_BRIGHTNESS;
 40	else
 41		value = brightness;
 42
 43	ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
 44	if (ret < 0)
 45		goto out;
 46
 47	if (!data->current_brightness && brightness)
 48		/* enable WLED output */
 49		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
 50	else if (!brightness)
 51		/* disable WLED output */
 52		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
 53	if (ret < 0)
 54		goto out;
 55	dev_dbg(chip->dev, "set brightness %d\n", value);
 56	data->current_brightness = value;
 57	return 0;
 58out:
 59	dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
 60		value, ret);
 61	return ret;
 62}
 63
 64static int max8925_backlight_update_status(struct backlight_device *bl)
 65{
 66	return max8925_backlight_set(bl, backlight_get_brightness(bl));
 67}
 68
 69static int max8925_backlight_get_brightness(struct backlight_device *bl)
 70{
 71	struct max8925_backlight_data *data = bl_get_data(bl);
 72	struct max8925_chip *chip = data->chip;
 73	int ret;
 74
 75	ret = max8925_reg_read(chip->i2c, data->reg_cntl);
 76	if (ret < 0)
 77		return -EINVAL;
 78	data->current_brightness = ret;
 79	dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
 80	return ret;
 81}
 82
 83static const struct backlight_ops max8925_backlight_ops = {
 84	.options	= BL_CORE_SUSPENDRESUME,
 85	.update_status	= max8925_backlight_update_status,
 86	.get_brightness	= max8925_backlight_get_brightness,
 87};
 88
 89static void max8925_backlight_dt_init(struct platform_device *pdev)
 90{
 91	struct device_node *nproot = pdev->dev.parent->of_node, *np;
 92	struct max8925_backlight_pdata *pdata;
 93	u32 val;
 94
 95	if (!nproot || !IS_ENABLED(CONFIG_OF))
 96		return;
 97
 98	pdata = devm_kzalloc(&pdev->dev,
 99			     sizeof(struct max8925_backlight_pdata),
100			     GFP_KERNEL);
101	if (!pdata)
102		return;
103
104	np = of_get_child_by_name(nproot, "backlight");
105	if (!np) {
106		dev_err(&pdev->dev, "failed to find backlight node\n");
107		return;
108	}
109
110	if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
111		pdata->dual_string = val;
112
113	of_node_put(np);
114
115	pdev->dev.platform_data = pdata;
116}
117
118static int max8925_backlight_probe(struct platform_device *pdev)
119{
120	struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
121	struct max8925_backlight_pdata *pdata;
122	struct max8925_backlight_data *data;
123	struct backlight_device *bl;
124	struct backlight_properties props;
125	struct resource *res;
126	unsigned char value;
127	int ret = 0;
128
129	data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
130			    GFP_KERNEL);
131	if (data == NULL)
132		return -ENOMEM;
133
134	res = platform_get_resource(pdev, IORESOURCE_REG, 0);
135	if (!res) {
136		dev_err(&pdev->dev, "No REG resource for mode control!\n");
137		return -ENXIO;
138	}
139	data->reg_mode_cntl = res->start;
140	res = platform_get_resource(pdev, IORESOURCE_REG, 1);
141	if (!res) {
142		dev_err(&pdev->dev, "No REG resource for control!\n");
143		return -ENXIO;
144	}
145	data->reg_cntl = res->start;
146
147	data->chip = chip;
148	data->current_brightness = 0;
149
150	memset(&props, 0, sizeof(struct backlight_properties));
151	props.type = BACKLIGHT_RAW;
152	props.max_brightness = MAX_BRIGHTNESS;
153	bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
154					&pdev->dev, data,
155					&max8925_backlight_ops, &props);
156	if (IS_ERR(bl)) {
157		dev_err(&pdev->dev, "failed to register backlight\n");
158		return PTR_ERR(bl);
159	}
160	bl->props.brightness = MAX_BRIGHTNESS;
161
162	platform_set_drvdata(pdev, bl);
163
164	value = 0;
165	if (!pdev->dev.platform_data)
166		max8925_backlight_dt_init(pdev);
167
168	pdata = pdev->dev.platform_data;
169	if (pdata) {
170		if (pdata->lxw_scl)
171			value |= (1 << 7);
172		if (pdata->lxw_freq)
173			value |= (LWX_FREQ(pdata->lxw_freq) << 4);
174		if (pdata->dual_string)
175			value |= (1 << 1);
176	}
177	ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
178	if (ret < 0)
179		return ret;
180	backlight_update_status(bl);
181	return 0;
182}
183
184static struct platform_driver max8925_backlight_driver = {
185	.driver		= {
186		.name	= "max8925-backlight",
187	},
188	.probe		= max8925_backlight_probe,
189};
190
191module_platform_driver(max8925_backlight_driver);
192
193MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
194MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
195MODULE_LICENSE("GPL");
196MODULE_ALIAS("platform:max8925-backlight");