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/driver.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_PORTB 0x82
25 #define REG_PORTC 0x83
26 #define REG_POWERON 0x85
27 #define REG_PWM 0x86
28 #define REG_ADDR_L 0x8c
29 #define REG_ADDR_H 0x8d
30 #define REG_WRITE_DATA_H 0x90
31 #define REG_WRITE_DATA_L 0x91
32
33 #define PA_LCD_DITHB BIT(0)
34 #define PA_LCD_MODE BIT(1)
35 #define PA_LCD_LR BIT(2)
36 #define PA_LCD_UD BIT(3)
37
38 #define PB_BRIDGE_PWRDNX_N BIT(0)
39 #define PB_LCD_VCC_N BIT(1)
40 #define PB_LCD_MAIN BIT(7)
41
42 #define PC_LED_EN BIT(0)
43 #define PC_RST_TP_N BIT(1)
44 #define PC_RST_LCD_N BIT(2)
45 #define PC_RST_BRIDGE_N BIT(3)
46
47 enum gpio_signals {
48 RST_BRIDGE_N, /* TC358762 bridge reset */
49 RST_TP_N, /* Touch controller reset */
50 NUM_GPIO
51 };
52
53 struct gpio_signal_mappings {
54 unsigned int reg;
55 unsigned int mask;
56 };
57
58 static const struct gpio_signal_mappings mappings[NUM_GPIO] = {
59 [RST_BRIDGE_N] = { REG_PORTC, PC_RST_BRIDGE_N | PC_RST_LCD_N },
60 [RST_TP_N] = { REG_PORTC, PC_RST_TP_N },
61 };
62
63 struct attiny_lcd {
64 /* lock to serialise overall accesses to the Atmel */
65 struct mutex lock;
66 struct regmap *regmap;
67 bool gpio_states[NUM_GPIO];
68 u8 port_states[3];
69
70 struct gpio_chip gc;
71 };
72
73 static const struct regmap_config attiny_regmap_config = {
74 .reg_bits = 8,
75 .val_bits = 8,
76 .disable_locking = 1,
77 .max_register = REG_WRITE_DATA_L,
78 .cache_type = REGCACHE_RBTREE,
79 };
80
attiny_set_port_state(struct attiny_lcd * state,int reg,u8 val)81 static int attiny_set_port_state(struct attiny_lcd *state, int reg, u8 val)
82 {
83 state->port_states[reg - REG_PORTA] = val;
84 return regmap_write(state->regmap, reg, val);
85 };
86
attiny_get_port_state(struct attiny_lcd * state,int reg)87 static u8 attiny_get_port_state(struct attiny_lcd *state, int reg)
88 {
89 return state->port_states[reg - REG_PORTA];
90 };
91
attiny_lcd_power_enable(struct regulator_dev * rdev)92 static int attiny_lcd_power_enable(struct regulator_dev *rdev)
93 {
94 struct attiny_lcd *state = rdev_get_drvdata(rdev);
95
96 mutex_lock(&state->lock);
97
98 /* Ensure bridge, and tp stay in reset */
99 attiny_set_port_state(state, REG_PORTC, 0);
100 usleep_range(5000, 10000);
101
102 /* Default to the same orientation as the closed source
103 * firmware used for the panel. Runtime rotation
104 * configuration will be supported using VC4's plane
105 * orientation bits.
106 */
107 attiny_set_port_state(state, REG_PORTA, PA_LCD_LR);
108 usleep_range(5000, 10000);
109 /* Main regulator on, and power to the panel (LCD_VCC_N) */
110 attiny_set_port_state(state, REG_PORTB, PB_LCD_MAIN);
111 usleep_range(5000, 10000);
112 /* Bring controllers out of reset */
113 attiny_set_port_state(state, REG_PORTC, PC_LED_EN);
114
115 msleep(80);
116
117 mutex_unlock(&state->lock);
118
119 return 0;
120 }
121
attiny_lcd_power_disable(struct regulator_dev * rdev)122 static int attiny_lcd_power_disable(struct regulator_dev *rdev)
123 {
124 struct attiny_lcd *state = rdev_get_drvdata(rdev);
125
126 mutex_lock(&state->lock);
127
128 regmap_write(rdev->regmap, REG_PWM, 0);
129 usleep_range(5000, 10000);
130
131 attiny_set_port_state(state, REG_PORTA, 0);
132 usleep_range(5000, 10000);
133 attiny_set_port_state(state, REG_PORTB, PB_LCD_VCC_N);
134 usleep_range(5000, 10000);
135 attiny_set_port_state(state, REG_PORTC, 0);
136 msleep(30);
137
138 mutex_unlock(&state->lock);
139
140 return 0;
141 }
142
attiny_lcd_power_is_enabled(struct regulator_dev * rdev)143 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
144 {
145 struct attiny_lcd *state = rdev_get_drvdata(rdev);
146 unsigned int data;
147 int ret, i;
148
149 mutex_lock(&state->lock);
150
151 for (i = 0; i < 10; i++) {
152 ret = regmap_read(rdev->regmap, REG_PORTC, &data);
153 if (!ret)
154 break;
155 usleep_range(10000, 12000);
156 }
157
158 mutex_unlock(&state->lock);
159
160 if (ret < 0)
161 return ret;
162
163 return data & PC_RST_BRIDGE_N;
164 }
165
166 static const struct regulator_init_data attiny_regulator_default = {
167 .constraints = {
168 .valid_ops_mask = REGULATOR_CHANGE_STATUS,
169 },
170 };
171
172 static const struct regulator_ops attiny_regulator_ops = {
173 .enable = attiny_lcd_power_enable,
174 .disable = attiny_lcd_power_disable,
175 .is_enabled = attiny_lcd_power_is_enabled,
176 };
177
178 static const struct regulator_desc attiny_regulator = {
179 .name = "tc358762-power",
180 .ops = &attiny_regulator_ops,
181 .type = REGULATOR_VOLTAGE,
182 .owner = THIS_MODULE,
183 };
184
attiny_update_status(struct backlight_device * bl)185 static int attiny_update_status(struct backlight_device *bl)
186 {
187 struct attiny_lcd *state = bl_get_data(bl);
188 struct regmap *regmap = state->regmap;
189 int brightness = backlight_get_brightness(bl);
190 int ret, i;
191
192 mutex_lock(&state->lock);
193
194 for (i = 0; i < 10; i++) {
195 ret = regmap_write(regmap, REG_PWM, brightness);
196 if (!ret)
197 break;
198 }
199
200 mutex_unlock(&state->lock);
201
202 return ret;
203 }
204
205 static const struct backlight_ops attiny_bl = {
206 .update_status = attiny_update_status,
207 };
208
attiny_gpio_get_direction(struct gpio_chip * gc,unsigned int off)209 static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
210 {
211 return GPIO_LINE_DIRECTION_OUT;
212 }
213
attiny_gpio_set(struct gpio_chip * gc,unsigned int off,int val)214 static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
215 {
216 struct attiny_lcd *state = gpiochip_get_data(gc);
217 u8 last_val;
218
219 if (off >= NUM_GPIO)
220 return;
221
222 mutex_lock(&state->lock);
223
224 last_val = attiny_get_port_state(state, mappings[off].reg);
225 if (val)
226 last_val |= mappings[off].mask;
227 else
228 last_val &= ~mappings[off].mask;
229
230 attiny_set_port_state(state, mappings[off].reg, last_val);
231
232 if (off == RST_BRIDGE_N && val) {
233 usleep_range(5000, 8000);
234 regmap_write(state->regmap, REG_ADDR_H, 0x04);
235 usleep_range(5000, 8000);
236 regmap_write(state->regmap, REG_ADDR_L, 0x7c);
237 usleep_range(5000, 8000);
238 regmap_write(state->regmap, REG_WRITE_DATA_H, 0x00);
239 usleep_range(5000, 8000);
240 regmap_write(state->regmap, REG_WRITE_DATA_L, 0x00);
241
242 msleep(100);
243 }
244
245 mutex_unlock(&state->lock);
246 }
247
attiny_i2c_read(struct i2c_client * client,u8 reg,unsigned int * buf)248 static int attiny_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)
249 {
250 struct i2c_msg msgs[1];
251 u8 addr_buf[1] = { reg };
252 u8 data_buf[1] = { 0, };
253 int ret;
254
255 /* Write register address */
256 msgs[0].addr = client->addr;
257 msgs[0].flags = 0;
258 msgs[0].len = ARRAY_SIZE(addr_buf);
259 msgs[0].buf = addr_buf;
260
261 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
262 if (ret != ARRAY_SIZE(msgs))
263 return -EIO;
264
265 usleep_range(5000, 10000);
266
267 /* Read data from register */
268 msgs[0].addr = client->addr;
269 msgs[0].flags = I2C_M_RD;
270 msgs[0].len = 1;
271 msgs[0].buf = data_buf;
272
273 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
274 if (ret != ARRAY_SIZE(msgs))
275 return -EIO;
276
277 *buf = data_buf[0];
278 return 0;
279 }
280
281 /*
282 * I2C driver interface functions
283 */
attiny_i2c_probe(struct i2c_client * i2c)284 static int attiny_i2c_probe(struct i2c_client *i2c)
285 {
286 struct backlight_properties props = { };
287 struct regulator_config config = { };
288 struct backlight_device *bl;
289 struct regulator_dev *rdev;
290 struct attiny_lcd *state;
291 struct regmap *regmap;
292 unsigned int data;
293 int ret;
294
295 state = devm_kzalloc(&i2c->dev, sizeof(*state), GFP_KERNEL);
296 if (!state)
297 return -ENOMEM;
298
299 mutex_init(&state->lock);
300 i2c_set_clientdata(i2c, state);
301
302 regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
303 if (IS_ERR(regmap)) {
304 ret = PTR_ERR(regmap);
305 dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
306 ret);
307 goto error;
308 }
309
310 ret = attiny_i2c_read(i2c, REG_ID, &data);
311 if (ret < 0) {
312 dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
313 goto error;
314 }
315
316 switch (data) {
317 case 0xde: /* ver 1 */
318 case 0xc3: /* ver 2 */
319 break;
320 default:
321 dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
322 ret = -ENODEV;
323 goto error;
324 }
325
326 regmap_write(regmap, REG_POWERON, 0);
327 msleep(30);
328 regmap_write(regmap, REG_PWM, 0);
329
330 config.dev = &i2c->dev;
331 config.regmap = regmap;
332 config.of_node = i2c->dev.of_node;
333 config.init_data = &attiny_regulator_default;
334 config.driver_data = state;
335
336 rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
337 if (IS_ERR(rdev)) {
338 dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
339 ret = PTR_ERR(rdev);
340 goto error;
341 }
342
343 props.type = BACKLIGHT_RAW;
344 props.max_brightness = 0xff;
345
346 state->regmap = regmap;
347
348 bl = devm_backlight_device_register(&i2c->dev, dev_name(&i2c->dev),
349 &i2c->dev, state, &attiny_bl,
350 &props);
351 if (IS_ERR(bl)) {
352 ret = PTR_ERR(bl);
353 goto error;
354 }
355
356 bl->props.brightness = 0xff;
357
358 state->gc.parent = &i2c->dev;
359 state->gc.label = i2c->name;
360 state->gc.owner = THIS_MODULE;
361 state->gc.base = -1;
362 state->gc.ngpio = NUM_GPIO;
363
364 state->gc.set = attiny_gpio_set;
365 state->gc.get_direction = attiny_gpio_get_direction;
366 state->gc.can_sleep = true;
367
368 ret = devm_gpiochip_add_data(&i2c->dev, &state->gc, state);
369 if (ret) {
370 dev_err(&i2c->dev, "Failed to create gpiochip: %d\n", ret);
371 goto error;
372 }
373
374 return 0;
375
376 error:
377 mutex_destroy(&state->lock);
378
379 return ret;
380 }
381
attiny_i2c_remove(struct i2c_client * client)382 static void attiny_i2c_remove(struct i2c_client *client)
383 {
384 struct attiny_lcd *state = i2c_get_clientdata(client);
385
386 mutex_destroy(&state->lock);
387 }
388
389 static const struct of_device_id attiny_dt_ids[] = {
390 { .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
391 {},
392 };
393 MODULE_DEVICE_TABLE(of, attiny_dt_ids);
394
395 static struct i2c_driver attiny_regulator_driver = {
396 .driver = {
397 .name = "rpi_touchscreen_attiny",
398 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
399 .of_match_table = attiny_dt_ids,
400 },
401 .probe = attiny_i2c_probe,
402 .remove = attiny_i2c_remove,
403 };
404
405 module_i2c_driver(attiny_regulator_driver);
406
407 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
408 MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
409 MODULE_LICENSE("GPL v2");
410