input_gt911.c

/*
 * Copyright (c) 2020 NXP
 * Copyright (c) 2020 Mark Olsson <mark@markolsson.se>
 * Copyright (c) 2020 Teslabs Engineering S.L.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define DT_DRV_COMPAT goodix_gt911

#include <zephyr/drivers/gpio.h>
#include <zephyr/drivers/i2c.h>
#include <zephyr/input/input.h>
#include <zephyr/sys/byteorder.h>

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(gt911, CONFIG_INPUT_LOG_LEVEL);

/* GT911 used registers */
#define DEVICE_ID           __bswap_16(0x8140U)
#define REG_STATUS		    __bswap_16(0x814EU)
#define REG_FIRST_POINT		__bswap_16(0x814FU)

/* REG_TD_STATUS: Touch points. */
#define TOUCH_POINTS_MSK	0x0FU

/* REG_TD_STATUS: Pressed. */
#define TOUCH_STATUS_MSK    (1 << 7U)

/* The GT911's config */
#define GT911_CONFIG_REG         __bswap_16(0x8047U)
#define REG_CONFIG_VERSION GT911_CONFIG_REG
#define REG_CONFIG_SIZE (186U)
#define GT911_PRODUCT_ID (0x00313139U)

/** GT911 configuration (DT). */
struct gt911_config {
	/** I2C bus. */
	struct i2c_dt_spec bus;
	struct gpio_dt_spec rst_gpio;
	/** Interrupt GPIO information. */
	struct gpio_dt_spec int_gpio;
	/* Alternate fallback I2C address */
	uint8_t alt_addr;
};

/** GT911 data. */
struct gt911_data {
	/** Device pointer. */
	const struct device *dev;
	/** Work queue (for deferred read). */
	struct k_work work;
	/** Actual device I2C address */
	uint8_t actual_address;
#ifdef CONFIG_INPUT_GT911_INTERRUPT
	/** Interrupt GPIO callback. */
	struct gpio_callback int_gpio_cb;
#else
	/** Timer (polling mode). */
	struct k_timer timer;
#endif
};

/** gt911 point reg */
struct  gt911_point_reg_t {
	uint8_t id;       /*!< Track ID. */
	uint8_t lowX;     /*!< Low byte of x coordinate. */
	uint8_t highX;    /*!< High byte of x coordinate. */
	uint8_t lowY;     /*!< Low byte of y coordinate. */
	uint8_t highY;    /*!< High byte of x coordinate. */
	uint8_t lowSize;  /*!< Low byte of point size. */
	uint8_t highSize; /*!< High byte of point size. */
	uint8_t reserved; /*!< Reserved. */
};

/*
 * Device-specific wrappers around i2c_write_dt and i2c_write_read_dt.
 * These wrappers handle the case where the GT911 did not accept the requested
 * I2C address, and the alternate I2C address is used.
 */
static int gt911_i2c_write(const struct device *dev,
			   const uint8_t *buf, uint32_t num_bytes)
{
	const struct gt911_config *config = dev->config;
	struct gt911_data *data = dev->data;

	return i2c_write(config->bus.bus, buf, num_bytes, data->actual_address);
}

static int gt911_i2c_write_read(const struct device *dev,
				const void *write_buf, size_t num_write,
				void *read_buf, size_t num_read)
{
	const struct gt911_config *config = dev->config;
	struct gt911_data *data = dev->data;

	return i2c_write_read(config->bus.bus, data->actual_address, write_buf,
			      num_write, read_buf, num_read);
}

static int gt911_process(const struct device *dev)
{
	int r;
	uint16_t reg_addr;
	uint8_t status;
	uint8_t points;
	struct gt911_point_reg_t pointRegs;
	uint16_t row, col;
	bool pressed;

	/* obtain number of touch points (NOTE: multi-touch ignored) */
	reg_addr = REG_STATUS;
	r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr),
				 &status, sizeof(status));
	if (r < 0) {
		return r;
	}

	points = status & TOUCH_POINTS_MSK;
	if (points != 0U && points != 1U && (0 != (status & TOUCH_STATUS_MSK))) {
		points = 1;
	}

	if (!(status & TOUCH_STATUS_MSK)) {
		/* Status bit not set, ignore this event */
		return 0;
	}
	/* need to clear the status */
	uint8_t clear_buffer[3] = {(uint8_t)REG_STATUS, (uint8_t)(REG_STATUS >> 8), 0};

	r = gt911_i2c_write(dev, clear_buffer, sizeof(clear_buffer));
	if (r < 0) {
		return r;
	}

	/* obtain first point X, Y coordinates and event from:
	 * REG_P1_XH, REG_P1_XL, REG_P1_YH, REG_P1_YL.
	 */
	reg_addr = REG_FIRST_POINT;
	r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr),
				 &pointRegs, sizeof(pointRegs));
	if (r < 0) {
		return r;
	}

	pressed = (points == 1);
	row = ((pointRegs.highY) << 8U) | pointRegs.lowY;
	col = ((pointRegs.highX) << 8U) | pointRegs.lowX;

	LOG_DBG("pressed: %d, row: %d, col: %d", pressed, row, col);

	if (pressed) {
		input_report_abs(dev, INPUT_ABS_X, col, false, K_FOREVER);
		input_report_abs(dev, INPUT_ABS_Y, row, false, K_FOREVER);
		input_report_key(dev, INPUT_BTN_TOUCH, 1, true, K_FOREVER);
	} else {
		input_report_key(dev, INPUT_BTN_TOUCH, 0, true, K_FOREVER);
	}

	return 0;
}

static void gt911_work_handler(struct k_work *work)
{
	struct gt911_data *data = CONTAINER_OF(work, struct gt911_data, work);

	gt911_process(data->dev);
}

#ifdef CONFIG_INPUT_GT911_INTERRUPT
static void gt911_isr_handler(const struct device *dev,
			       struct gpio_callback *cb, uint32_t pins)
{
	struct gt911_data *data = CONTAINER_OF(cb, struct gt911_data, int_gpio_cb);

	k_work_submit(&data->work);
}
#else
static void gt911_timer_handler(struct k_timer *timer)
{
	struct gt911_data *data = CONTAINER_OF(timer, struct gt911_data, timer);

	k_work_submit(&data->work);
}
#endif

static uint8_t gt911_get_firmware_checksum(const uint8_t *firmware)
{
	uint8_t sum = 0;
	uint16_t i  = 0;

	for (i = 0; i < REG_CONFIG_SIZE - 2U; i++) {
		sum += (*firmware);
		firmware++;
	}

	return (~sum + 1U);
}

static bool gt911_verify_firmware(const uint8_t *firmware)
{
	return ((firmware[REG_CONFIG_VERSION - GT911_CONFIG_REG] != 0U) &&
		(gt911_get_firmware_checksum(firmware) == firmware[REG_CONFIG_SIZE - 2U]));
}

static int gt911_init(const struct device *dev)
{
	const struct gt911_config *config = dev->config;
	struct gt911_data *data = dev->data;

	if (!i2c_is_ready_dt(&config->bus)) {
		LOG_ERR("I2C controller device not ready");
		return -ENODEV;
	}

	data->dev = dev;
	data->actual_address = config->bus.addr;

	k_work_init(&data->work, gt911_work_handler);

	int r;

	if (!gpio_is_ready_dt(&config->int_gpio)) {
		LOG_ERR("Interrupt GPIO controller device not ready");
		return -ENODEV;
	}

	if (!gpio_is_ready_dt(&config->rst_gpio)) {
		LOG_ERR("Reset GPIO controller device not ready");
		return -ENODEV;
	}

	r = gpio_pin_configure_dt(&config->rst_gpio, GPIO_OUTPUT_INACTIVE);
	if (r < 0) {
		LOG_ERR("Could not configure reset GPIO pin");
		return r;
	}

	if (config->alt_addr == 0x0) {
		/*
		 * We need to configure the int-pin to 0, in order to enter the
		 * AddressMode0. Keeping the INT pin low during the reset sequence
		 * should result in the device selecting an I2C address of 0x5D.
		 * Note we skip this step if an alternate I2C address is set,
		 * and fall through to probing for the actual address.
		 */
		r = gpio_pin_configure_dt(&config->int_gpio, GPIO_OUTPUT_INACTIVE);
		if (r < 0) {
			LOG_ERR("Could not configure int GPIO pin");
			return r;
		}
	}
	/* Delay at least 10 ms after power on before we configure gt911 */
	k_sleep(K_MSEC(20));
	/* reset the device and confgiure the addr mode0 */
	gpio_pin_set_dt(&config->rst_gpio, 0);
	/* hold down at least 1us, 1ms here */
	k_sleep(K_MSEC(1));
	gpio_pin_set_dt(&config->rst_gpio, 1);
	/* hold down at least 5ms. This is the point the INT pin must be low. */
	k_sleep(K_MSEC(5));
	/* hold down 50ms to make sure the address available */
	k_sleep(K_MSEC(50));

	r = gpio_pin_configure_dt(&config->int_gpio, GPIO_INPUT);
	if (r < 0) {
		LOG_ERR("Could not configure interrupt GPIO pin");
		return r;
	}

#ifdef CONFIG_INPUT_GT911_INTERRUPT
	r = gpio_pin_interrupt_configure_dt(&config->int_gpio,
					    GPIO_INT_EDGE_TO_ACTIVE);
	if (r < 0) {
		LOG_ERR("Could not configure interrupt GPIO interrupt.");
		return r;
	}

	gpio_init_callback(&data->int_gpio_cb, gt911_isr_handler,
			   BIT(config->int_gpio.pin));
#else
	k_timer_init(&data->timer, gt911_timer_handler, NULL);
#endif

	/* check the Device ID first: '911' */
	uint32_t reg_id = 0;
	uint16_t reg_addr = DEVICE_ID;

	if (config->alt_addr != 0x0) {
		/*
		 * The level of the INT pin during reset is used by the GT911
		 * to select the I2C address mode. If an alternate I2C address
		 * is set, we should probe the GT911 to determine which address
		 * it actually selected. This is useful for boards that do not
		 * route the INT pin, or can only read it as an input (IE when
		 * using a level shifter).
		 */
		r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr),
					 &reg_id, sizeof(reg_id));
		if (r < 0) {
			/* Try alternate address */
			data->actual_address = config->alt_addr;
			r = gt911_i2c_write_read(dev, &reg_addr,
						 sizeof(reg_addr),
						 &reg_id, sizeof(reg_id));
			LOG_INF("Device did not accept I2C address, "
				"updated to 0x%02X", data->actual_address);
		}
	} else {
		r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr),
					 &reg_id, sizeof(reg_id));
	}
	if (r < 0) {
		LOG_ERR("Device did not respond to I2C request");
		return r;
	}
	if (reg_id != GT911_PRODUCT_ID) {
		LOG_ERR("The Device ID is not correct");
		return -ENODEV;
	}

	/* need to setup the firmware first: read and write */
	uint8_t gt911Config[REG_CONFIG_SIZE + 2] = {
		(uint8_t)GT911_CONFIG_REG, (uint8_t)(GT911_CONFIG_REG >> 8)
	};

	reg_addr = GT911_CONFIG_REG;
	r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr),
				 gt911Config + 2, REG_CONFIG_SIZE);
	if (r < 0) {
		return r;
	}
	if (!gt911_verify_firmware(gt911Config + 2)) {
		return -ENODEV;
	}

	gt911Config[REG_CONFIG_SIZE] = gt911_get_firmware_checksum(gt911Config + 2);
	gt911Config[REG_CONFIG_SIZE + 1] = 1;

	r = gt911_i2c_write(dev, gt911Config, sizeof(gt911Config));
	if (r < 0) {
		return r;
	}

#ifdef CONFIG_INPUT_GT911_INTERRUPT
	r = gpio_add_callback(config->int_gpio.port, &data->int_gpio_cb);
	if (r < 0) {
		LOG_ERR("Could not set gpio callback");
		return r;
	}
#else
	k_timer_start(&data->timer, K_MSEC(CONFIG_INPUT_GT911_PERIOD_MS),
		      K_MSEC(CONFIG_INPUT_GT911_PERIOD_MS));
#endif

	return 0;
}

#define GT911_INIT(index)                                                      \
	static const struct gt911_config gt911_config_##index = {	       \
		.bus = I2C_DT_SPEC_INST_GET(index),			       \
		.rst_gpio = GPIO_DT_SPEC_INST_GET(index, reset_gpios),	       \
		.int_gpio = GPIO_DT_SPEC_INST_GET(index, irq_gpios),	       \
		.alt_addr = DT_INST_PROP_OR(index, alt_addr, 0),	       \
	};								       \
	static struct gt911_data gt911_data_##index;			       \
	DEVICE_DT_INST_DEFINE(index, gt911_init, NULL,			       \
			    &gt911_data_##index, &gt911_config_##index,        \
			    POST_KERNEL, CONFIG_INPUT_INIT_PRIORITY,	       \
			    NULL);

DT_INST_FOREACH_STATUS_OKAY(GT911_INIT)