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
47enum gpio_signals {
48	RST_BRIDGE_N,	/* TC358762 bridge reset */
49	RST_TP_N,	/* Touch controller reset */
50	NUM_GPIO
51};
52
53struct gpio_signal_mappings {
54	unsigned int reg;
55	unsigned int mask;
56};
57
58static 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
63struct 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
73static 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
81static 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
87static u8 attiny_get_port_state(struct attiny_lcd *state, int reg)
88{
89	return state->port_states[reg - REG_PORTA];
90};
91
92static 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
122static 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
143static 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
166static const struct regulator_init_data attiny_regulator_default = {
167	.constraints = {
168		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
169	},
170};
171
172static 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
178static 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
185static 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
205static const struct backlight_ops attiny_bl = {
206	.update_status	= attiny_update_status,
207};
208
209static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
210{
211	return GPIO_LINE_DIRECTION_OUT;
212}
213
214static 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
248static 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 */
284static 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
376error:
377	mutex_destroy(&state->lock);
378
379	return ret;
380}
381
382static 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
389static const struct of_device_id attiny_dt_ids[] = {
390	{ .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
391	{},
392};
393MODULE_DEVICE_TABLE(of, attiny_dt_ids);
394
395static 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
405module_i2c_driver(attiny_regulator_driver);
406
407MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
408MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
409MODULE_LICENSE("GPL v2");
410