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/cleanup.h>
10 #include <linux/err.h>
11 #include <linux/gpio/driver.h>
12 #include <linux/i2c.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/module.h>
16 #include <linux/mutex.h>
17 #include <linux/regmap.h>
18 #include <linux/regulator/driver.h>
19 #include <linux/regulator/machine.h>
20 #include <linux/regulator/of_regulator.h>
21 #include <linux/slab.h>
22
23 /* I2C registers of the Atmel microcontroller. */
24 #define REG_ID 0x80
25 #define REG_PORTA 0x81
26 #define REG_PORTB 0x82
27 #define REG_PORTC 0x83
28 #define REG_POWERON 0x85
29 #define REG_PWM 0x86
30 #define REG_ADDR_L 0x8c
31 #define REG_ADDR_H 0x8d
32 #define REG_WRITE_DATA_H 0x90
33 #define REG_WRITE_DATA_L 0x91
34
35 #define PA_LCD_DITHB BIT(0)
36 #define PA_LCD_MODE BIT(1)
37 #define PA_LCD_LR BIT(2)
38 #define PA_LCD_UD BIT(3)
39
40 #define PB_BRIDGE_PWRDNX_N BIT(0)
41 #define PB_LCD_VCC_N BIT(1)
42 #define PB_LCD_MAIN BIT(7)
43
44 #define PC_LED_EN BIT(0)
45 #define PC_RST_TP_N BIT(1)
46 #define PC_RST_LCD_N BIT(2)
47 #define PC_RST_BRIDGE_N BIT(3)
48
49 enum gpio_signals {
50 RST_BRIDGE_N, /* TC358762 bridge reset */
51 RST_TP_N, /* Touch controller reset */
52 NUM_GPIO
53 };
54
55 struct gpio_signal_mappings {
56 unsigned int reg;
57 unsigned int mask;
58 };
59
60 static const struct gpio_signal_mappings mappings[NUM_GPIO] = {
61 [RST_BRIDGE_N] = { REG_PORTC, PC_RST_BRIDGE_N | PC_RST_LCD_N },
62 [RST_TP_N] = { REG_PORTC, PC_RST_TP_N },
63 };
64
65 struct attiny_lcd {
66 /* lock to serialise overall accesses to the Atmel */
67 struct mutex lock;
68 struct regmap *regmap;
69 bool gpio_states[NUM_GPIO];
70 u8 port_states[3];
71
72 struct gpio_chip gc;
73 };
74
75 static const struct regmap_config attiny_regmap_config = {
76 .reg_bits = 8,
77 .val_bits = 8,
78 .disable_locking = 1,
79 .max_register = REG_WRITE_DATA_L,
80 .cache_type = REGCACHE_MAPLE,
81 };
82
attiny_set_port_state(struct attiny_lcd * state,int reg,u8 val)83 static int attiny_set_port_state(struct attiny_lcd *state, int reg, u8 val)
84 {
85 state->port_states[reg - REG_PORTA] = val;
86 return regmap_write(state->regmap, reg, val);
87 };
88
attiny_get_port_state(struct attiny_lcd * state,int reg)89 static u8 attiny_get_port_state(struct attiny_lcd *state, int reg)
90 {
91 return state->port_states[reg - REG_PORTA];
92 };
93
attiny_lcd_power_enable(struct regulator_dev * rdev)94 static int attiny_lcd_power_enable(struct regulator_dev *rdev)
95 {
96 struct attiny_lcd *state = rdev_get_drvdata(rdev);
97
98 guard(mutex)(&state->lock);
99
100 /* Ensure bridge, and tp stay in reset */
101 attiny_set_port_state(state, REG_PORTC, 0);
102 usleep_range(5000, 10000);
103
104 /* Default to the same orientation as the closed source
105 * firmware used for the panel. Runtime rotation
106 * configuration will be supported using VC4's plane
107 * orientation bits.
108 */
109 attiny_set_port_state(state, REG_PORTA, PA_LCD_LR);
110 usleep_range(5000, 10000);
111 /* Main regulator on, and power to the panel (LCD_VCC_N) */
112 attiny_set_port_state(state, REG_PORTB, PB_LCD_MAIN);
113 usleep_range(5000, 10000);
114 /* Bring controllers out of reset */
115 attiny_set_port_state(state, REG_PORTC, PC_LED_EN);
116
117 msleep(80);
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 guard(mutex)(&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 return 0;
139 }
140
attiny_lcd_power_is_enabled(struct regulator_dev * rdev)141 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
142 {
143 struct attiny_lcd *state = rdev_get_drvdata(rdev);
144 unsigned int data;
145 int ret = 0, i;
146
147 scoped_guard(mutex, &state->lock) {
148 for (i = 0; i < 10; i++) {
149 ret = regmap_read(rdev->regmap, REG_PORTC, &data);
150 if (!ret)
151 break;
152 usleep_range(10000, 12000);
153 }
154 }
155
156 if (ret < 0)
157 return ret;
158
159 return data & PC_RST_BRIDGE_N;
160 }
161
162 static const struct regulator_init_data attiny_regulator_default = {
163 .constraints = {
164 .valid_ops_mask = REGULATOR_CHANGE_STATUS,
165 },
166 };
167
168 static const struct regulator_ops attiny_regulator_ops = {
169 .enable = attiny_lcd_power_enable,
170 .disable = attiny_lcd_power_disable,
171 .is_enabled = attiny_lcd_power_is_enabled,
172 };
173
174 static const struct regulator_desc attiny_regulator = {
175 .name = "tc358762-power",
176 .ops = &attiny_regulator_ops,
177 .type = REGULATOR_VOLTAGE,
178 .owner = THIS_MODULE,
179 };
180
attiny_update_status(struct backlight_device * bl)181 static int attiny_update_status(struct backlight_device *bl)
182 {
183 struct attiny_lcd *state = bl_get_data(bl);
184 struct regmap *regmap = state->regmap;
185 int brightness = backlight_get_brightness(bl);
186 int ret, i;
187
188 guard(mutex)(&state->lock);
189
190 for (i = 0; i < 10; i++) {
191 ret = regmap_write(regmap, REG_PWM, brightness);
192 if (!ret)
193 break;
194 }
195
196 return ret;
197 }
198
199 static const struct backlight_ops attiny_bl = {
200 .update_status = attiny_update_status,
201 };
202
attiny_gpio_get_direction(struct gpio_chip * gc,unsigned int off)203 static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
204 {
205 return GPIO_LINE_DIRECTION_OUT;
206 }
207
attiny_gpio_set(struct gpio_chip * gc,unsigned int off,int val)208 static int attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
209 {
210 struct attiny_lcd *state = gpiochip_get_data(gc);
211 u8 last_val;
212
213 guard(mutex)(&state->lock);
214
215 last_val = attiny_get_port_state(state, mappings[off].reg);
216 if (val)
217 last_val |= mappings[off].mask;
218 else
219 last_val &= ~mappings[off].mask;
220
221 attiny_set_port_state(state, mappings[off].reg, last_val);
222
223 if (off == RST_BRIDGE_N && val) {
224 usleep_range(5000, 8000);
225 regmap_write(state->regmap, REG_ADDR_H, 0x04);
226 usleep_range(5000, 8000);
227 regmap_write(state->regmap, REG_ADDR_L, 0x7c);
228 usleep_range(5000, 8000);
229 regmap_write(state->regmap, REG_WRITE_DATA_H, 0x00);
230 usleep_range(5000, 8000);
231 regmap_write(state->regmap, REG_WRITE_DATA_L, 0x00);
232
233 msleep(100);
234 }
235
236 return 0;
237 }
238
attiny_i2c_read(struct i2c_client * client,u8 reg,unsigned int * buf)239 static int attiny_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)
240 {
241 struct i2c_msg msgs[1];
242 u8 addr_buf[1] = { reg };
243 u8 data_buf[1] = { 0, };
244 int ret;
245
246 /* Write register address */
247 msgs[0].addr = client->addr;
248 msgs[0].flags = 0;
249 msgs[0].len = ARRAY_SIZE(addr_buf);
250 msgs[0].buf = addr_buf;
251
252 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
253 if (ret != ARRAY_SIZE(msgs))
254 return -EIO;
255
256 usleep_range(5000, 10000);
257
258 /* Read data from register */
259 msgs[0].addr = client->addr;
260 msgs[0].flags = I2C_M_RD;
261 msgs[0].len = 1;
262 msgs[0].buf = data_buf;
263
264 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
265 if (ret != ARRAY_SIZE(msgs))
266 return -EIO;
267
268 *buf = data_buf[0];
269 return 0;
270 }
271
272 /*
273 * I2C driver interface functions
274 */
attiny_i2c_probe(struct i2c_client * i2c)275 static int attiny_i2c_probe(struct i2c_client *i2c)
276 {
277 struct backlight_properties props = { };
278 struct regulator_config config = { };
279 struct backlight_device *bl;
280 struct regulator_dev *rdev;
281 struct attiny_lcd *state;
282 struct regmap *regmap;
283 unsigned int data;
284 int ret;
285
286 state = devm_kzalloc(&i2c->dev, sizeof(*state), GFP_KERNEL);
287 if (!state)
288 return -ENOMEM;
289
290 ret = devm_mutex_init(&i2c->dev, &state->lock);
291 if (ret)
292 return ret;
293
294 i2c_set_clientdata(i2c, state);
295
296 regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
297 if (IS_ERR(regmap)) {
298 ret = PTR_ERR(regmap);
299 dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
300 ret);
301 return ret;
302 }
303
304 ret = attiny_i2c_read(i2c, REG_ID, &data);
305 if (ret < 0) {
306 dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
307 return ret;
308 }
309
310 switch (data) {
311 case 0xde: /* ver 1 */
312 case 0xc3: /* ver 2 */
313 break;
314 default:
315 dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
316 return -ENODEV;
317 }
318
319 regmap_write(regmap, REG_POWERON, 0);
320 msleep(30);
321 regmap_write(regmap, REG_PWM, 0);
322
323 config.dev = &i2c->dev;
324 config.regmap = regmap;
325 config.of_node = i2c->dev.of_node;
326 config.init_data = &attiny_regulator_default;
327 config.driver_data = state;
328
329 rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
330 if (IS_ERR(rdev)) {
331 dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
332 return PTR_ERR(rdev);
333 }
334
335 props.type = BACKLIGHT_RAW;
336 props.max_brightness = 0xff;
337
338 state->regmap = regmap;
339
340 bl = devm_backlight_device_register(&i2c->dev, dev_name(&i2c->dev),
341 &i2c->dev, state, &attiny_bl,
342 &props);
343 if (IS_ERR(bl))
344 return PTR_ERR(bl);
345
346 bl->props.brightness = 0xff;
347
348 state->gc.parent = &i2c->dev;
349 state->gc.label = i2c->name;
350 state->gc.owner = THIS_MODULE;
351 state->gc.base = -1;
352 state->gc.ngpio = NUM_GPIO;
353
354 state->gc.set_rv = attiny_gpio_set;
355 state->gc.get_direction = attiny_gpio_get_direction;
356 state->gc.can_sleep = true;
357
358 ret = devm_gpiochip_add_data(&i2c->dev, &state->gc, state);
359 if (ret)
360 dev_err(&i2c->dev, "Failed to create gpiochip: %d\n", ret);
361
362 return ret;
363 }
364
365 static const struct of_device_id attiny_dt_ids[] = {
366 { .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
367 {},
368 };
369 MODULE_DEVICE_TABLE(of, attiny_dt_ids);
370
371 static struct i2c_driver attiny_regulator_driver = {
372 .driver = {
373 .name = "rpi_touchscreen_attiny",
374 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
375 .of_match_table = attiny_dt_ids,
376 },
377 .probe = attiny_i2c_probe,
378 };
379
380 module_i2c_driver(attiny_regulator_driver);
381
382 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
383 MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
384 MODULE_LICENSE("GPL v2");
385