rpi-panel-attiny-regulator.c

  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
 49enum gpio_signals {
 50	RST_BRIDGE_N,	/* TC358762 bridge reset */
 51	RST_TP_N,	/* Touch controller reset */
 52	NUM_GPIO
 53};
 54
 55struct gpio_signal_mappings {
 56	unsigned int reg;
 57	unsigned int mask;
 58};
 59
 60static 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
 65struct 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
 75static 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
 83static 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
 89static u8 attiny_get_port_state(struct attiny_lcd *state, int reg)
 90{
 91	return state->port_states[reg - REG_PORTA];
 92};
 93
 94static 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
122static 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
141static 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
162static const struct regulator_init_data attiny_regulator_default = {
163	.constraints = {
164		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
165	},
166};
167
168static 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
174static 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
181static 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
199static const struct backlight_ops attiny_bl = {
200	.update_status	= attiny_update_status,
201};
202
203static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
204{
205	return GPIO_LINE_DIRECTION_OUT;
206}
207
208static 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
239static 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 */
275static 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 = 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
365static const struct of_device_id attiny_dt_ids[] = {
366	{ .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
367	{},
368};
369MODULE_DEVICE_TABLE(of, attiny_dt_ids);
370
371static 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
380module_i2c_driver(attiny_regulator_driver);
381
382MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
383MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
384MODULE_LICENSE("GPL v2");