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
attiny_lcd_power_enable(struct regulator_dev * rdev)37 static int attiny_lcd_power_enable(struct regulator_dev *rdev)
38 {
39 unsigned int data;
40 int ret, i;
41
42 regmap_write(rdev->regmap, REG_POWERON, 1);
43 msleep(80);
44
45 /* Wait for nPWRDWN to go low to indicate poweron is done. */
46 for (i = 0; i < 20; i++) {
47 ret = regmap_read(rdev->regmap, REG_PORTB, &data);
48 if (!ret) {
49 if (data & BIT(0))
50 break;
51 }
52 usleep_range(10000, 12000);
53 }
54 usleep_range(10000, 12000);
55
56 if (ret)
57 pr_err("%s: regmap_read_poll_timeout failed %d\n", __func__, ret);
58
59 /* Default to the same orientation as the closed source
60 * firmware used for the panel. Runtime rotation
61 * configuration will be supported using VC4's plane
62 * orientation bits.
63 */
64 regmap_write(rdev->regmap, REG_PORTA, BIT(2));
65
66 return 0;
67 }
68
attiny_lcd_power_disable(struct regulator_dev * rdev)69 static int attiny_lcd_power_disable(struct regulator_dev *rdev)
70 {
71 regmap_write(rdev->regmap, REG_PWM, 0);
72 regmap_write(rdev->regmap, REG_POWERON, 0);
73 msleep(30);
74 return 0;
75 }
76
attiny_lcd_power_is_enabled(struct regulator_dev * rdev)77 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
78 {
79 unsigned int data;
80 int ret, i;
81
82 for (i = 0; i < 10; i++) {
83 ret = regmap_read(rdev->regmap, REG_POWERON, &data);
84 if (!ret)
85 break;
86 usleep_range(10000, 12000);
87 }
88 if (ret < 0)
89 return ret;
90
91 if (!(data & BIT(0)))
92 return 0;
93
94 for (i = 0; i < 10; i++) {
95 ret = regmap_read(rdev->regmap, REG_PORTB, &data);
96 if (!ret)
97 break;
98 usleep_range(10000, 12000);
99 }
100
101 if (ret < 0)
102 return ret;
103
104 return data & BIT(0);
105 }
106
107 static const struct regulator_init_data attiny_regulator_default = {
108 .constraints = {
109 .valid_ops_mask = REGULATOR_CHANGE_STATUS,
110 },
111 };
112
113 static const struct regulator_ops attiny_regulator_ops = {
114 .enable = attiny_lcd_power_enable,
115 .disable = attiny_lcd_power_disable,
116 .is_enabled = attiny_lcd_power_is_enabled,
117 };
118
119 static const struct regulator_desc attiny_regulator = {
120 .name = "tc358762-power",
121 .ops = &attiny_regulator_ops,
122 .type = REGULATOR_VOLTAGE,
123 .owner = THIS_MODULE,
124 };
125
attiny_update_status(struct backlight_device * bl)126 static int attiny_update_status(struct backlight_device *bl)
127 {
128 struct regmap *regmap = bl_get_data(bl);
129 int brightness = bl->props.brightness;
130 int ret, i;
131
132 if (bl->props.power != FB_BLANK_UNBLANK ||
133 bl->props.fb_blank != FB_BLANK_UNBLANK)
134 brightness = 0;
135
136 for (i = 0; i < 10; i++) {
137 ret = regmap_write(regmap, REG_PWM, brightness);
138 if (!ret)
139 break;
140 }
141
142 return ret;
143 }
144
attiny_get_brightness(struct backlight_device * bl)145 static int attiny_get_brightness(struct backlight_device *bl)
146 {
147 struct regmap *regmap = bl_get_data(bl);
148 int ret, brightness, i;
149
150 for (i = 0; i < 10; i++) {
151 ret = regmap_read(regmap, REG_PWM, &brightness);
152 if (!ret)
153 break;
154 }
155
156 if (ret)
157 return ret;
158
159 return brightness;
160 }
161
162 static const struct backlight_ops attiny_bl = {
163 .update_status = attiny_update_status,
164 .get_brightness = attiny_get_brightness,
165 };
166
167 /*
168 * I2C driver interface functions
169 */
attiny_i2c_probe(struct i2c_client * i2c,const struct i2c_device_id * id)170 static int attiny_i2c_probe(struct i2c_client *i2c,
171 const struct i2c_device_id *id)
172 {
173 struct backlight_properties props = { };
174 struct regulator_config config = { };
175 struct backlight_device *bl;
176 struct regulator_dev *rdev;
177 struct regmap *regmap;
178 unsigned int data;
179 int ret;
180
181 regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
182 if (IS_ERR(regmap)) {
183 ret = PTR_ERR(regmap);
184 dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
185 ret);
186 return ret;
187 }
188
189 ret = regmap_read(regmap, REG_ID, &data);
190 if (ret < 0) {
191 dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
192 return ret;
193 }
194
195 switch (data) {
196 case 0xde: /* ver 1 */
197 case 0xc3: /* ver 2 */
198 break;
199 default:
200 dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
201 return -ENODEV;
202 }
203
204 regmap_write(regmap, REG_POWERON, 0);
205 msleep(30);
206
207 config.dev = &i2c->dev;
208 config.regmap = regmap;
209 config.of_node = i2c->dev.of_node;
210 config.init_data = &attiny_regulator_default;
211
212 rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
213 if (IS_ERR(rdev)) {
214 dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
215 return PTR_ERR(rdev);
216 }
217
218 props.type = BACKLIGHT_RAW;
219 props.max_brightness = 0xff;
220 bl = devm_backlight_device_register(&i2c->dev,
221 "7inch-touchscreen-panel-bl",
222 &i2c->dev, regmap, &attiny_bl,
223 &props);
224 if (IS_ERR(bl))
225 return PTR_ERR(bl);
226
227 bl->props.brightness = 0xff;
228
229 return 0;
230 }
231
232 static const struct of_device_id attiny_dt_ids[] = {
233 { .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
234 {},
235 };
236 MODULE_DEVICE_TABLE(of, attiny_dt_ids);
237
238 static struct i2c_driver attiny_regulator_driver = {
239 .driver = {
240 .name = "rpi_touchscreen_attiny",
241 .of_match_table = of_match_ptr(attiny_dt_ids),
242 },
243 .probe = attiny_i2c_probe,
244 };
245
246 module_i2c_driver(attiny_regulator_driver);
247
248 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
249 MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
250 MODULE_LICENSE("GPL v2");
251