mipi_dbi_spi.c

/*
 * Copyright 2023 NXP
 * Copyright 2024 TiaC Systems
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define DT_DRV_COMPAT zephyr_mipi_dbi_spi

#include <zephyr/drivers/mipi_dbi.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/sys/byteorder.h>

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(mipi_dbi_spi, CONFIG_MIPI_DBI_LOG_LEVEL);

struct mipi_dbi_spi_config {
	/* SPI hardware used to send data */
	const struct device *spi_dev;
	/* Command/Data gpio */
	const struct gpio_dt_spec cmd_data;
	/* Reset GPIO */
	const struct gpio_dt_spec reset;
	/* Minimum transfer bits */
	const uint8_t xfr_min_bits;
};

struct mipi_dbi_spi_data {
	struct k_mutex lock;
	/* Used for 3 wire mode */
	uint16_t spi_byte;
};

/* Expands to 1 if the node does not have the `write-only` property */
#define _WRITE_ONLY_ABSENT(n) (!DT_INST_PROP(n, write_only)) |

/* This macro will evaluate to 1 if any of the nodes with zephyr,mipi-dbi-spi
 * lack a `write-only` property. The intention here is to allow the entire
 * command_read function to be optimized out when it is not needed.
 */
#define MIPI_DBI_SPI_READ_REQUIRED DT_INST_FOREACH_STATUS_OKAY(_WRITE_ONLY_ABSENT) 0
uint32_t var = MIPI_DBI_SPI_READ_REQUIRED;

/* Expands to 1 if the node does reflect the enum in `xfr-min-bits` property */
#define _XFR_8BITS(n) (DT_INST_PROP(n, xfr_min_bits) == MIPI_DBI_SPI_XFR_8BIT) |
#define _XFR_16BITS(n) (DT_INST_PROP(n, xfr_min_bits) == MIPI_DBI_SPI_XFR_16BIT) |

/* This macros will evaluate to 1 if any of the nodes with zephyr,mipi-dbi-spi
 * have the `xfr-min-bits` property to corresponding enum value. The intention
 * here is to allow the write helper functions to be optimized out when not all
 * minimum transfer bits will be needed.
 */
#define MIPI_DBI_SPI_WRITE_8BIT_REQUIRED DT_INST_FOREACH_STATUS_OKAY(_XFR_8BITS) 0
#define MIPI_DBI_SPI_WRITE_16BIT_REQUIRED DT_INST_FOREACH_STATUS_OKAY(_XFR_16BITS) 0

/* In Type C mode 1 MIPI BIT communication, the 9th bit of the word
 * (first bit sent in each word) indicates if the word is a command or
 * data. Typically 0 indicates a command and 1 indicates data, but some
 * displays may vary.
 * Index starts from 0 so that BIT(8) means 9th bit.
 */
#define MIPI_DBI_DC_BIT BIT(8)

static inline int
mipi_dbi_spi_write_helper_3wire(const struct device *dev,
				const struct mipi_dbi_config *dbi_config,
				bool cmd_present, uint8_t cmd,
				const uint8_t *data_buf, size_t len)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct mipi_dbi_spi_data *data = dev->data;
	struct spi_buf buffer;
	struct spi_buf_set buf_set = {
		.buffers = &buffer,
		.count = 1,
	};
	int ret = 0;

	/*
	 * 9 bit word mode must be used, as the command/data bit
	 * is stored before the data word.
	 */

	if ((dbi_config->config.operation & SPI_WORD_SIZE_MASK)
	    != SPI_WORD_SET(9)) {
		return -ENOTSUP;
	}
	buffer.buf = &data->spi_byte;
	buffer.len = 2;

	/* Send command */
	if (cmd_present) {
		data->spi_byte = cmd;
		ret = spi_write(config->spi_dev, &dbi_config->config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}
	/* Write data, byte by byte */
	for (size_t i = 0; i < len; i++) {
		data->spi_byte = MIPI_DBI_DC_BIT | data_buf[i];
		ret = spi_write(config->spi_dev, &dbi_config->config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}
out:
	return ret;
}

#if MIPI_DBI_SPI_WRITE_8BIT_REQUIRED

static inline int
mipi_dbi_spi_write_helper_4wire_8bit(const struct device *dev,
				     const struct mipi_dbi_config *dbi_config,
				     bool cmd_present, uint8_t cmd,
				     const uint8_t *data_buf, size_t len)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct spi_buf buffer;
	struct spi_buf_set buf_set = {
		.buffers = &buffer,
		.count = 1,
	};
	int ret = 0;

	/*
	 * 4 wire mode is much simpler. We just toggle the
	 * command/data GPIO to indicate if we are sending
	 * a command or data
	 */

	buffer.buf = &cmd;
	buffer.len = sizeof(cmd);

	if (cmd_present) {
		/* Set CD pin low for command */
		gpio_pin_set_dt(&config->cmd_data, 0);
		ret = spi_write(config->spi_dev, &dbi_config->config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}

	if (len > 0) {
		buffer.buf = (void *)data_buf;
		buffer.len = len;

		/* Set CD pin high for data */
		gpio_pin_set_dt(&config->cmd_data, 1);
		ret = spi_write(config->spi_dev, &dbi_config->config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}
out:
	return ret;
}

#endif /* MIPI_DBI_SPI_WRITE_8BIT_REQUIRED */

#if MIPI_DBI_SPI_WRITE_16BIT_REQUIRED

static inline int
mipi_dbi_spi_write_helper_4wire_16bit(const struct device *dev,
				      const struct mipi_dbi_config *dbi_config,
				      bool cmd_present, uint8_t cmd,
				      const uint8_t *data_buf, size_t len)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct spi_buf buffer;
	struct spi_buf_set buf_set = {
		.buffers = &buffer,
		.count = 1,
	};
	uint16_t data16;
	int ret = 0;

	/*
	 * 4 wire mode with toggle the command/data GPIO
	 * to indicate if we are sending a command or data
	 * but send 16-bit blocks (with bit stuffing).
	 */

	if (cmd_present) {
		data16 = sys_cpu_to_be16(cmd);
		buffer.buf = &data16;
		buffer.len = sizeof(data16);

		/* Set CD pin low for command */
		gpio_pin_set_dt(&config->cmd_data, 0);
		ret = spi_write(config->spi_dev, &dbi_config->config,
				&buf_set);
		if (ret < 0) {
			goto out;
		}

		/* Set CD pin high for data, if there are any */
		if (len > 0) {
			gpio_pin_set_dt(&config->cmd_data, 1);
		}

		/* iterate command data */
		for (int i = 0; i < len; i++) {
			data16 = sys_cpu_to_be16(data_buf[i]);

			ret = spi_write(config->spi_dev, &dbi_config->config,
					&buf_set);
			if (ret < 0) {
				goto out;
			}
		}
	} else {
		int stuffing = len % sizeof(data16);

		/* Set CD pin high for data, if there are any */
		if (len > 0) {
			gpio_pin_set_dt(&config->cmd_data, 1);
		}

		/* pass through generic device data */
		if (len - stuffing > 0) {
			buffer.buf = (void *)data_buf;
			buffer.len = len - stuffing;

			ret = spi_write(config->spi_dev, &dbi_config->config,
					&buf_set);
			if (ret < 0) {
				goto out;
			}
		}

		/* iterate remaining data with stuffing */
		for (int i = len - stuffing; i < len; i++) {
			data16 = sys_cpu_to_be16(data_buf[i]);
			buffer.buf = &data16;
			buffer.len = sizeof(data16);

			ret = spi_write(config->spi_dev, &dbi_config->config,
					&buf_set);
			if (ret < 0) {
				goto out;
			}
		}
	}
out:
	return ret;
}

#endif /* MIPI_DBI_SPI_WRITE_16BIT_REQUIRED */

static int mipi_dbi_spi_write_helper(const struct device *dev,
				     const struct mipi_dbi_config *dbi_config,
				     bool cmd_present, uint8_t cmd,
				     const uint8_t *data_buf, size_t len)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct mipi_dbi_spi_data *data = dev->data;
	int ret = 0;

	ret = k_mutex_lock(&data->lock, K_FOREVER);
	if (ret < 0) {
		return ret;
	}

	if (dbi_config->mode == MIPI_DBI_MODE_SPI_3WIRE &&
	    IS_ENABLED(CONFIG_MIPI_DBI_SPI_3WIRE)) {
		ret = mipi_dbi_spi_write_helper_3wire(dev, dbi_config,
						      cmd_present, cmd,
						      data_buf, len);
		goto out;
	}

	if (dbi_config->mode == MIPI_DBI_MODE_SPI_4WIRE) {

#if MIPI_DBI_SPI_WRITE_8BIT_REQUIRED
		if (config->xfr_min_bits == MIPI_DBI_SPI_XFR_8BIT) {
			ret = mipi_dbi_spi_write_helper_4wire_8bit(
							dev, dbi_config,
							cmd_present, cmd,
							data_buf, len);
			goto out;
		}
#endif

#if MIPI_DBI_SPI_WRITE_16BIT_REQUIRED
		if (config->xfr_min_bits == MIPI_DBI_SPI_XFR_16BIT) {
			ret = mipi_dbi_spi_write_helper_4wire_16bit(
							dev, dbi_config,
							cmd_present, cmd,
							data_buf, len);
			goto out;
		}
#endif

	}

	/* Otherwise, unsupported mode */
	ret = -ENOTSUP;

out:
	k_mutex_unlock(&data->lock);
	return ret;
}

static int mipi_dbi_spi_command_write(const struct device *dev,
				      const struct mipi_dbi_config *dbi_config,
				      uint8_t cmd, const uint8_t *data_buf,
				      size_t len)
{
	return mipi_dbi_spi_write_helper(dev, dbi_config, true, cmd,
					 data_buf, len);
}

static int mipi_dbi_spi_write_display(const struct device *dev,
				      const struct mipi_dbi_config *dbi_config,
				      const uint8_t *framebuf,
				      struct display_buffer_descriptor *desc,
				      enum display_pixel_format pixfmt)
{
	ARG_UNUSED(pixfmt);

	return mipi_dbi_spi_write_helper(dev, dbi_config, false, 0x0,
					 framebuf, desc->buf_size);
}

#if MIPI_DBI_SPI_READ_REQUIRED

static inline int
mipi_dbi_spi_read_helper_3wire(const struct device *dev,
			       const struct mipi_dbi_config *dbi_config,
			       uint8_t *cmds, size_t num_cmds,
			       uint8_t *response, size_t len)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct mipi_dbi_spi_data *data = dev->data;
	struct spi_config tmp_config;
	struct spi_buf buffer;
	struct spi_buf_set buf_set = {
		.buffers = &buffer,
		.count = 1,
	};
	int ret = 0;

	/*
	 * We have to emulate 3 wire mode by packing the data/command
	 * bit into the upper bit of the SPI transfer, switch SPI to
	 * 9 bit mode, and write the transfer.
	 */

	if ((dbi_config->config.operation & SPI_WORD_SIZE_MASK)
	    != SPI_WORD_SET(9)) {
		return -ENOTSUP;
	}

	memcpy(&tmp_config, &dbi_config->config, sizeof(tmp_config));
	tmp_config.operation &= ~SPI_WORD_SIZE_MASK;
	tmp_config.operation |= SPI_WORD_SET(9);

	buffer.buf = &data->spi_byte;
	buffer.len = 1;

	/* Send each command */
	for (size_t i = 0; i < num_cmds; i++) {
		data->spi_byte = cmds[i];
		ret = spi_write(config->spi_dev, &tmp_config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}

	/* Now, we can switch to 8 bit mode, and read data */
	buffer.buf = (void *)response;
	buffer.len = len;
	ret = spi_read(config->spi_dev, &dbi_config->config, &buf_set);

out:
	spi_release(config->spi_dev, &tmp_config); /* Really necessary here? */
	return ret;
}

static inline int
mipi_dbi_spi_read_helper_4wire(const struct device *dev,
			       const struct mipi_dbi_config *dbi_config,
			       uint8_t *cmds, size_t num_cmds,
			       uint8_t *response, size_t len)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct spi_config tmp_config;
	struct spi_buf buffer;
	struct spi_buf_set buf_set = {
		.buffers = &buffer,
		.count = 1,
	};
	int ret = 0;

	/*
	 * 4 wire mode is much simpler. We just toggle the
	 * command/data GPIO to indicate if we are sending
	 * a command or data. Note that since some SPI displays
	 * require CS to be held low for the entire read sequence,
	 * we set SPI_HOLD_ON_CS
	 */

	memcpy(&tmp_config, &dbi_config->config, sizeof(tmp_config));
	tmp_config.operation |= SPI_HOLD_ON_CS;

	if (num_cmds > 0) {
		buffer.buf = cmds;
		buffer.len = num_cmds;

		/* Set CD pin low for command */
		gpio_pin_set_dt(&config->cmd_data, 0);

		ret = spi_write(config->spi_dev, &tmp_config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}

	if (len > 0) {
		buffer.buf = (void *)response;
		buffer.len = len;

		/* Set CD pin high for data */
		gpio_pin_set_dt(&config->cmd_data, 1);

		ret = spi_read(config->spi_dev, &tmp_config, &buf_set);
		if (ret < 0) {
			goto out;
		}
	}

out:
	spi_release(config->spi_dev, &tmp_config);
	return ret;
}

static int mipi_dbi_spi_command_read(const struct device *dev,
				     const struct mipi_dbi_config *dbi_config,
				     uint8_t *cmds, size_t num_cmds,
				     uint8_t *response, size_t len)
{
	struct mipi_dbi_spi_data *data = dev->data;
	int ret = 0;

	ret = k_mutex_lock(&data->lock, K_FOREVER);
	if (ret < 0) {
		return ret;
	}
	if (dbi_config->mode == MIPI_DBI_MODE_SPI_3WIRE &&
	    IS_ENABLED(CONFIG_MIPI_DBI_SPI_3WIRE)) {
		ret = mipi_dbi_spi_read_helper_3wire(dev, dbi_config,
						     cmds, num_cmds,
						     response, len);
		if (ret < 0) {
			goto out;
		}
	} else if (dbi_config->mode == MIPI_DBI_MODE_SPI_4WIRE) {
		ret = mipi_dbi_spi_read_helper_4wire(dev, dbi_config,
						     cmds, num_cmds,
						     response, len);
		if (ret < 0) {
			goto out;
		}
	} else {
		/* Otherwise, unsupported mode */
		ret = -ENOTSUP;
	}
out:
	k_mutex_unlock(&data->lock);
	return ret;
}

#endif /* MIPI_DBI_SPI_READ_REQUIRED */

static inline bool mipi_dbi_has_pin(const struct gpio_dt_spec *spec)
{
	return spec->port != NULL;
}

static int mipi_dbi_spi_reset(const struct device *dev, k_timeout_t delay)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	int ret;

	if (!mipi_dbi_has_pin(&config->reset)) {
		return -ENOTSUP;
	}

	ret = gpio_pin_set_dt(&config->reset, 1);
	if (ret < 0) {
		return ret;
	}
	k_sleep(delay);
	return gpio_pin_set_dt(&config->reset, 0);
}

static int mipi_dbi_spi_release(const struct device *dev,
				const struct mipi_dbi_config *dbi_config)
{
	const struct mipi_dbi_spi_config *config = dev->config;

	return spi_release(config->spi_dev, &dbi_config->config);
}

static int mipi_dbi_spi_init(const struct device *dev)
{
	const struct mipi_dbi_spi_config *config = dev->config;
	struct mipi_dbi_spi_data *data = dev->data;
	int ret;

	if (!device_is_ready(config->spi_dev)) {
		LOG_ERR("SPI device is not ready");
		return -ENODEV;
	}

	if (mipi_dbi_has_pin(&config->cmd_data)) {
		if (!gpio_is_ready_dt(&config->cmd_data)) {
			return -ENODEV;
		}
		ret = gpio_pin_configure_dt(&config->cmd_data, GPIO_OUTPUT);
		if (ret < 0) {
			LOG_ERR("Could not configure command/data GPIO (%d)", ret);
			return ret;
		}
	}

	if (mipi_dbi_has_pin(&config->reset)) {
		if (!gpio_is_ready_dt(&config->reset)) {
			return -ENODEV;
		}
		ret = gpio_pin_configure_dt(&config->reset, GPIO_OUTPUT_INACTIVE);
		if (ret < 0) {
			LOG_ERR("Could not configure reset GPIO (%d)", ret);
			return ret;
		}
	}

	k_mutex_init(&data->lock);

	return 0;
}

static DEVICE_API(mipi_dbi, mipi_dbi_spi_driver_api) = {
	.reset = mipi_dbi_spi_reset,
	.command_write = mipi_dbi_spi_command_write,
	.write_display = mipi_dbi_spi_write_display,
	.release = mipi_dbi_spi_release,
#if MIPI_DBI_SPI_READ_REQUIRED
	.command_read = mipi_dbi_spi_command_read,
#endif
};

#define MIPI_DBI_SPI_INIT(n)							\
	static const struct mipi_dbi_spi_config					\
	    mipi_dbi_spi_config_##n = {						\
		    .spi_dev = DEVICE_DT_GET(					\
				    DT_INST_PHANDLE(n, spi_dev)),		\
		    .cmd_data = GPIO_DT_SPEC_INST_GET_OR(n, dc_gpios, {}),	\
		    .reset = GPIO_DT_SPEC_INST_GET_OR(n, reset_gpios, {}),	\
		    .xfr_min_bits = DT_INST_PROP(n, xfr_min_bits)               \
	};									\
	static struct mipi_dbi_spi_data mipi_dbi_spi_data_##n;			\
										\
	DEVICE_DT_INST_DEFINE(n, mipi_dbi_spi_init, NULL,			\
			&mipi_dbi_spi_data_##n,					\
			&mipi_dbi_spi_config_##n,				\
			POST_KERNEL,						\
			CONFIG_MIPI_DBI_INIT_PRIORITY,				\
			&mipi_dbi_spi_driver_api);

DT_INST_FOREACH_STATUS_OKAY(MIPI_DBI_SPI_INIT)