1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2020 Marek Vasut <marex@denx.de>
4  *
5  * Based on rpi_touchscreen.c by Eric Anholt <eric@anholt.net>
6  */
7 
8 #include <linux/backlight.h>
9 #include <linux/err.h>
10 #include <linux/gpio.h>
11 #include <linux/i2c.h>
12 #include <linux/init.h>
13 #include <linux/interrupt.h>
14 #include <linux/module.h>
15 #include <linux/regmap.h>
16 #include <linux/regulator/driver.h>
17 #include <linux/regulator/machine.h>
18 #include <linux/regulator/of_regulator.h>
19 #include <linux/slab.h>
20 
21 /* I2C registers of the Atmel microcontroller. */
22 #define REG_ID		0x80
23 #define REG_PORTA	0x81
24 #define REG_PORTA_HF	BIT(2)
25 #define REG_PORTA_VF	BIT(3)
26 #define REG_PORTB	0x82
27 #define REG_POWERON	0x85
28 #define REG_PWM		0x86
29 
30 static const struct regmap_config attiny_regmap_config = {
31 	.reg_bits = 8,
32 	.val_bits = 8,
33 	.max_register = REG_PWM,
34 	.cache_type = REGCACHE_NONE,
35 };
36 
37 static int attiny_lcd_power_enable(struct regulator_dev *rdev)
38 {
39 	unsigned int data;
40 
41 	regmap_write(rdev->regmap, REG_POWERON, 1);
42 	/* Wait for nPWRDWN to go low to indicate poweron is done. */
43 	regmap_read_poll_timeout(rdev->regmap, REG_PORTB, data,
44 					data & BIT(0), 10, 1000000);
45 
46 	/* Default to the same orientation as the closed source
47 	 * firmware used for the panel.  Runtime rotation
48 	 * configuration will be supported using VC4's plane
49 	 * orientation bits.
50 	 */
51 	regmap_write(rdev->regmap, REG_PORTA, BIT(2));
52 
53 	return 0;
54 }
55 
56 static int attiny_lcd_power_disable(struct regulator_dev *rdev)
57 {
58 	regmap_write(rdev->regmap, REG_PWM, 0);
59 	regmap_write(rdev->regmap, REG_POWERON, 0);
60 	udelay(1);
61 	return 0;
62 }
63 
64 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
65 {
66 	unsigned int data;
67 	int ret;
68 
69 	ret = regmap_read(rdev->regmap, REG_POWERON, &data);
70 	if (ret < 0)
71 		return ret;
72 
73 	if (!(data & BIT(0)))
74 		return 0;
75 
76 	ret = regmap_read(rdev->regmap, REG_PORTB, &data);
77 	if (ret < 0)
78 		return ret;
79 
80 	return data & BIT(0);
81 }
82 
83 static const struct regulator_init_data attiny_regulator_default = {
84 	.constraints = {
85 		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
86 	},
87 };
88 
89 static const struct regulator_ops attiny_regulator_ops = {
90 	.enable = attiny_lcd_power_enable,
91 	.disable = attiny_lcd_power_disable,
92 	.is_enabled = attiny_lcd_power_is_enabled,
93 };
94 
95 static const struct regulator_desc attiny_regulator = {
96 	.name	= "tc358762-power",
97 	.ops	= &attiny_regulator_ops,
98 	.type	= REGULATOR_VOLTAGE,
99 	.owner	= THIS_MODULE,
100 };
101 
102 static int attiny_update_status(struct backlight_device *bl)
103 {
104 	struct regmap *regmap = bl_get_data(bl);
105 	int brightness = bl->props.brightness;
106 
107 	if (bl->props.power != FB_BLANK_UNBLANK ||
108 	    bl->props.fb_blank != FB_BLANK_UNBLANK)
109 		brightness = 0;
110 
111 	return regmap_write(regmap, REG_PWM, brightness);
112 }
113 
114 static int attiny_get_brightness(struct backlight_device *bl)
115 {
116 	struct regmap *regmap = bl_get_data(bl);
117 	int ret, brightness;
118 
119 	ret = regmap_read(regmap, REG_PWM, &brightness);
120 	if (ret)
121 		return ret;
122 
123 	return brightness;
124 }
125 
126 static const struct backlight_ops attiny_bl = {
127 	.update_status	= attiny_update_status,
128 	.get_brightness	= attiny_get_brightness,
129 };
130 
131 /*
132  * I2C driver interface functions
133  */
134 static int attiny_i2c_probe(struct i2c_client *i2c,
135 		const struct i2c_device_id *id)
136 {
137 	struct backlight_properties props = { };
138 	struct regulator_config config = { };
139 	struct backlight_device *bl;
140 	struct regulator_dev *rdev;
141 	struct regmap *regmap;
142 	unsigned int data;
143 	int ret;
144 
145 	regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
146 	if (IS_ERR(regmap)) {
147 		ret = PTR_ERR(regmap);
148 		dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
149 			ret);
150 		return ret;
151 	}
152 
153 	ret = regmap_read(regmap, REG_ID, &data);
154 	if (ret < 0) {
155 		dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
156 		return ret;
157 	}
158 
159 	switch (data) {
160 	case 0xde: /* ver 1 */
161 	case 0xc3: /* ver 2 */
162 		break;
163 	default:
164 		dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
165 		return -ENODEV;
166 	}
167 
168 	regmap_write(regmap, REG_POWERON, 0);
169 	mdelay(1);
170 
171 	config.dev = &i2c->dev;
172 	config.regmap = regmap;
173 	config.of_node = i2c->dev.of_node;
174 	config.init_data = &attiny_regulator_default;
175 
176 	rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
177 	if (IS_ERR(rdev)) {
178 		dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
179 		return PTR_ERR(rdev);
180 	}
181 
182 	props.type = BACKLIGHT_RAW;
183 	props.max_brightness = 0xff;
184 	bl = devm_backlight_device_register(&i2c->dev,
185 					    "7inch-touchscreen-panel-bl",
186 					    &i2c->dev, regmap, &attiny_bl,
187 					    &props);
188 	if (IS_ERR(bl))
189 		return PTR_ERR(bl);
190 
191 	bl->props.brightness = 0xff;
192 
193 	return 0;
194 }
195 
196 static const struct of_device_id attiny_dt_ids[] = {
197 	{ .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
198 	{},
199 };
200 MODULE_DEVICE_TABLE(of, attiny_dt_ids);
201 
202 static struct i2c_driver attiny_regulator_driver = {
203 	.driver = {
204 		.name = "rpi_touchscreen_attiny",
205 		.of_match_table = of_match_ptr(attiny_dt_ids),
206 	},
207 	.probe = attiny_i2c_probe,
208 };
209 
210 module_i2c_driver(attiny_regulator_driver);
211 
212 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
213 MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
214 MODULE_LICENSE("GPL v2");
215