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)

/* 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 REG_GT911_CONFIG            BSWAP_16(0x8047U)
#define REG_CONFIG_VERSION          REG_GT911_CONFIG
#define REG_CONFIG_TOUCH_NUM_OFFSET 0x5
#define REG_CONFIG_SIZE             186U
#define GT911_PRODUCT_ID            0x00313139U

/* Points registers */
#define REG_POINT_0       0x814F
#define POINT_OFFSET      0x8
#define REG_POINT_ADDR(n) BSWAP_16(REG_POINT_0 + POINT_OFFSET * n)

/** 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 {
	uint8_t id;        /*!< Track ID. */
	uint8_t low_x;     /*!< Low byte of x coordinate. */
	uint8_t high_x;    /*!< High byte of x coordinate. */
	uint8_t low_y;     /*!< Low byte of y coordinate. */
	uint8_t high_y;    /*!< High byte of x coordinate. */
	uint8_t low_size;  /*!< Low byte of point size. */
	uint8_t high_size; /*!< 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 i;
	uint8_t j;
	uint16_t row;
	uint16_t col;
	uint8_t points;
	static uint8_t prev_points;
	struct gt911_point_reg point_reg[CONFIG_INPUT_GT911_MAX_TOUCH_POINTS];
	static struct gt911_point_reg prev_point_reg[CONFIG_INPUT_GT911_MAX_TOUCH_POINTS];

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

	if (!(status & TOUCH_STATUS_MSK)) {
		/* Status bit not set, ignore this event */
		return 0;
	}

	/*
	 * Note- since we program the max number of touch inputs during init,
	 * the controller won't report more than the maximum number of touch
	 * points we are configured to support
	 */
	points = status & TOUCH_POINTS_MSK;

	/* 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;
	}

	/* current points array */
	for (i = 0; i < points; i++) {
		reg_addr = REG_POINT_ADDR(i);
		r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr), &point_reg[i],
					 sizeof(point_reg[i]));

		if (r < 0) {
			return r;
		}
	}

	/* touch events */
	for (i = 0; i < points; i++) {
		if (CONFIG_INPUT_GT911_MAX_TOUCH_POINTS > 1) {
			input_report_abs(dev, INPUT_ABS_MT_SLOT, point_reg[i].id, true, K_FOREVER);
		}

		row = ((point_reg[i].high_y) << 8U) | point_reg[i].low_y;
		col = ((point_reg[i].high_x) << 8U) | point_reg[i].low_x;

		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);
	}

	/* release events */
	for (i = 0; i < prev_points; i++) {
		/* We look for the prev_point in the current points list */
		for (j = 0; j < points; j++) {
			if (prev_point_reg[i].id == point_reg[j].id) {
				break;
			}
		}

		if (j == points) {
			if (CONFIG_INPUT_GT911_MAX_TOUCH_POINTS > 1) {
				input_report_abs(dev, INPUT_ABS_MT_SLOT, prev_point_reg[i].id, true,
						 K_FOREVER);
			}
			row = ((prev_point_reg[i].high_y) << 8U) | prev_point_reg[i].low_y;
			col = ((prev_point_reg[i].high_x) << 8U) | prev_point_reg[i].low_x;
			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, 0, true, K_FOREVER);
		}
	}

	memcpy(prev_point_reg, point_reg, sizeof(point_reg));
	prev_points = points;

	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 - REG_GT911_CONFIG] != 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 (config->rst_gpio.port != NULL) {
		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_ACTIVE);
		if (r < 0) {
			LOG_ERR("Could not configure reset GPIO pin");
			return r;
		}
	}

	/*
	 * 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 that if an alternate I2C address is set, we will probe
	 * for the alternate address if 0x5D does not work. This is useful
	 * for boards that do not route the INT pin, or only permit it
	 * to be used as an input
	 */
	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));
	if (config->rst_gpio.port != NULL) {
		/* reset the device and confgiure the addr mode0 */
		gpio_pin_set_dt(&config->rst_gpio, 1);
		/* hold down at least 1us, 1ms here */
		k_sleep(K_MSEC(1));
		gpio_pin_set_dt(&config->rst_gpio, 0);
		/* 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 gt911_config_firmware[REG_CONFIG_SIZE + 2] = {(uint8_t)REG_GT911_CONFIG,
							      (uint8_t)(REG_GT911_CONFIG >> 8)};

	reg_addr = REG_GT911_CONFIG;
	r = gt911_i2c_write_read(dev, &reg_addr, sizeof(reg_addr), gt911_config_firmware + 2,
				 REG_CONFIG_SIZE);
	if (r < 0) {
		return r;
	}
	if (!gt911_verify_firmware(gt911_config_firmware + 2)) {
		return -ENODEV;
	}

	gt911_config_firmware[REG_CONFIG_TOUCH_NUM_OFFSET + 2] =
		CONFIG_INPUT_GT911_MAX_TOUCH_POINTS;

	gt911_config_firmware[REG_CONFIG_SIZE] =
		gt911_get_firmware_checksum(gt911_config_firmware + 2);
	gt911_config_firmware[REG_CONFIG_SIZE + 1] = 1;

	r = gt911_i2c_write(dev, gt911_config_firmware, sizeof(gt911_config_firmware));
	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_OR(index, reset_gpios, {0}),                     \
		.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)