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/fb.h>
13#include <linux/i2c.h>
14#include <linux/backlight.h>
15#include <linux/mfd/max8925.h>
16#include <linux/slab.h>
17#include <linux/module.h>
18
19#define MAX_BRIGHTNESS		(0xff)
20#define MIN_BRIGHTNESS		(0)
21
22#define LWX_FREQ(x)		(((x - 601) / 100) & 0x7)
23
24struct max8925_backlight_data {
25	struct max8925_chip	*chip;
26
27	int	current_brightness;
28	int	reg_mode_cntl;
29	int	reg_cntl;
30};
31
32static int max8925_backlight_set(struct backlight_device *bl, int brightness)
33{
34	struct max8925_backlight_data *data = bl_get_data(bl);
35	struct max8925_chip *chip = data->chip;
36	unsigned char value;
37	int ret;
38
39	if (brightness > MAX_BRIGHTNESS)
40		value = MAX_BRIGHTNESS;
41	else
42		value = brightness;
43
44	ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
45	if (ret < 0)
46		goto out;
47
48	if (!data->current_brightness && brightness)
49		/* enable WLED output */
50		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
51	else if (!brightness)
52		/* disable WLED output */
53		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
54	if (ret < 0)
55		goto out;
56	dev_dbg(chip->dev, "set brightness %d\n", value);
57	data->current_brightness = value;
58	return 0;
59out:
60	dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
61		value, ret);
62	return ret;
63}
64
65static int max8925_backlight_update_status(struct backlight_device *bl)
66{
67	return max8925_backlight_set(bl, backlight_get_brightness(bl));
68}
69
70static int max8925_backlight_get_brightness(struct backlight_device *bl)
71{
72	struct max8925_backlight_data *data = bl_get_data(bl);
73	struct max8925_chip *chip = data->chip;
74	int ret;
75
76	ret = max8925_reg_read(chip->i2c, data->reg_cntl);
77	if (ret < 0)
78		return -EINVAL;
79	data->current_brightness = ret;
80	dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
81	return ret;
82}
83
84static const struct backlight_ops max8925_backlight_ops = {
85	.options	= BL_CORE_SUSPENDRESUME,
86	.update_status	= max8925_backlight_update_status,
87	.get_brightness	= max8925_backlight_get_brightness,
88};
89
90static void max8925_backlight_dt_init(struct platform_device *pdev)
91{
92	struct device_node *nproot = pdev->dev.parent->of_node, *np;
93	struct max8925_backlight_pdata *pdata;
94	u32 val;
95
96	if (!nproot || !IS_ENABLED(CONFIG_OF))
97		return;
98
99	pdata = devm_kzalloc(&pdev->dev,
100			     sizeof(struct max8925_backlight_pdata),
101			     GFP_KERNEL);
102	if (!pdata)
103		return;
104
105	np = of_get_child_by_name(nproot, "backlight");
106	if (!np) {
107		dev_err(&pdev->dev, "failed to find backlight node\n");
108		return;
109	}
110
111	if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
112		pdata->dual_string = val;
113
114	of_node_put(np);
115
116	pdev->dev.platform_data = pdata;
117}
118
119static int max8925_backlight_probe(struct platform_device *pdev)
120{
121	struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
122	struct max8925_backlight_pdata *pdata;
123	struct max8925_backlight_data *data;
124	struct backlight_device *bl;
125	struct backlight_properties props;
126	struct resource *res;
127	unsigned char value;
128	int ret = 0;
129
130	data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
131			    GFP_KERNEL);
132	if (data == NULL)
133		return -ENOMEM;
134
135	res = platform_get_resource(pdev, IORESOURCE_REG, 0);
136	if (!res) {
137		dev_err(&pdev->dev, "No REG resource for mode control!\n");
138		return -ENXIO;
139	}
140	data->reg_mode_cntl = res->start;
141	res = platform_get_resource(pdev, IORESOURCE_REG, 1);
142	if (!res) {
143		dev_err(&pdev->dev, "No REG resource for control!\n");
144		return -ENXIO;
145	}
146	data->reg_cntl = res->start;
147
148	data->chip = chip;
149	data->current_brightness = 0;
150
151	memset(&props, 0, sizeof(struct backlight_properties));
152	props.type = BACKLIGHT_RAW;
153	props.max_brightness = MAX_BRIGHTNESS;
154	bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
155					&pdev->dev, data,
156					&max8925_backlight_ops, &props);
157	if (IS_ERR(bl)) {
158		dev_err(&pdev->dev, "failed to register backlight\n");
159		return PTR_ERR(bl);
160	}
161	bl->props.brightness = MAX_BRIGHTNESS;
162
163	platform_set_drvdata(pdev, bl);
164
165	value = 0;
166	if (!pdev->dev.platform_data)
167		max8925_backlight_dt_init(pdev);
168
169	pdata = pdev->dev.platform_data;
170	if (pdata) {
171		if (pdata->lxw_scl)
172			value |= (1 << 7);
173		if (pdata->lxw_freq)
174			value |= (LWX_FREQ(pdata->lxw_freq) << 4);
175		if (pdata->dual_string)
176			value |= (1 << 1);
177	}
178	ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
179	if (ret < 0)
180		return ret;
181	backlight_update_status(bl);
182	return 0;
183}
184
185static struct platform_driver max8925_backlight_driver = {
186	.driver		= {
187		.name	= "max8925-backlight",
188	},
189	.probe		= max8925_backlight_probe,
190};
191
192module_platform_driver(max8925_backlight_driver);
193
194MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
195MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
196MODULE_LICENSE("GPL");
197MODULE_ALIAS("platform:max8925-backlight");
198