drivers: mipi_dbi_spi: splitting SPI write function

The more complex the SPI transfer algorithms become, the more confusing the current implementation of the SPI write function becomes. Furthermore, if further as yet unknown MIPI DBI modes are to be supported, the scope of this implementation would increase dramatically. With the splitting now introduced, the existing SPI transfer algorithms are moved to individual auxiliary functions and the SPI write function only focus on the decision of the respective MIPI DBI mode and the device lock/unlock. Signed-off-by: Stephan Linz <[email protected]>
zephyrproject-rtos · Dec 9, 2024 · c809c37 · c809c37
1 parent d0ba5a3
commit c809c37
Showing 1 changed file with 102 additions and 59 deletions.
diff --git a/drivers/mipi_dbi/mipi_dbi_spi.c b/drivers/mipi_dbi/mipi_dbi_spi.c
@@ -46,10 +46,11 @@ uint32_t var = MIPI_DBI_SPI_READ_REQUIRED;
  */
 #define MIPI_DBI_DC_BIT BIT(8)
 
-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)
+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;
@@ -60,70 +61,112 @@ static int mipi_dbi_spi_write_helper(const struct device *dev,
 	};
 	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;
+}
+
+static inline int
+mipi_dbi_spi_write_helper_4wire(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;
+}
+
+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)
+{
+	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)) {
-		/* 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;
-			}
+		ret = mipi_dbi_spi_write_helper_3wire(dev, dbi_config,
+						      cmd_present, cmd,
+						      data_buf, len);
+		if (ret < 0) {
+			goto out;
 		}
 	} else if (dbi_config->mode == MIPI_DBI_MODE_SPI_4WIRE) {
-		/* 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;
-			}
+		ret = mipi_dbi_spi_write_helper_4wire(dev, dbi_config,
+						      cmd_present, cmd,
+						      data_buf, len);
+		if (ret < 0) {
+			goto out;
 		}
 	} else {
 		/* Otherwise, unsupported mode */