SSD16xx implement read support

drivers/display/ssd16xx.c

@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2022 Andreas Sandberg
  * Copyright (c) 2018-2020 PHYTEC Messtechnik GmbH
  *
  * SPDX-License-Identifier: Apache-2.0
@@ -18,6 +19,7 @@ LOG_MODULE_REGISTER(ssd16xx);
 #include <zephyr/drivers/spi.h>
 #include <zephyr/sys/byteorder.h>
 
+#include <zephyr/display/ssd16xx.h>
 #include "ssd16xx_regs.h"
 
 /**
@@ -32,6 +34,7 @@ LOG_MODULE_REGISTER(ssd16xx);
 #define SSD16XX_TR_SCALE_FACTOR		256U
 
 struct ssd16xx_data {
+	bool read_supported;
 	uint8_t scan_mode;
 	uint8_t update_cmd;
 	bool blanking_on;
@@ -114,6 +117,51 @@ static inline int ssd16xx_write_cmd(const struct device *dev, uint8_t cmd,
 	return err;
 }
 
+static inline int ssd16xx_read_cmd(const struct device *dev, uint8_t cmd,
+				    uint8_t *data, size_t len)
+{
+	const struct ssd16xx_config *config = dev->config;
+	const struct ssd16xx_data *dev_data = dev->data;
+	struct spi_buf buf = {.buf = &cmd, .len = sizeof(cmd)};
+	struct spi_buf_set buf_set = {.buffers = &buf, .count = 1};
+	int err = 0;
+
+	if (!dev_data->read_supported) {
+		return -ENOTSUP;
+	}
+
+	ssd16xx_busy_wait(dev);
+
+	err = gpio_pin_set_dt(&config->dc_gpio, 1);
+	if (err < 0) {
+		return err;
+	}
+
+	err = spi_write_dt(&config->bus, &buf_set);
+	if (err < 0) {
+		goto spi_out;
+	}
+
+	if (data != NULL) {
+		buf.buf = data;
+		buf.len = len;
+
+		err = gpio_pin_set_dt(&config->dc_gpio, 0);
+		if (err < 0) {
+			goto spi_out;
+		}
+
+		err = spi_read_dt(&config->bus, &buf_set);
+		if (err < 0) {
+			goto spi_out;
+		}
+	}
+
+spi_out:
+	spi_release_dt(&config->bus);
+	return err;
+}
+
 static inline size_t push_x_param(const struct device *dev,
 				  uint8_t *data, uint16_t x)
 {
@@ -231,15 +279,13 @@ static int ssd16xx_blanking_on(const struct device *dev)
 	return 0;
 }
 
-static int ssd16xx_write(const struct device *dev, const uint16_t x,
-			 const uint16_t y,
-			 const struct display_buffer_descriptor *desc,
-			 const void *buf)
+static int ssd16xx_set_window(const struct device *dev,
+			      const uint16_t x, const uint16_t y,
+			      const struct display_buffer_descriptor *desc)
 {
 	const struct ssd16xx_config *config = dev->config;
 	struct ssd16xx_data *data = dev->data;
 	int err;
-	size_t buf_len;
 	uint16_t x_start;
 	uint16_t x_end;
 	uint16_t y_start;
@@ -252,12 +298,6 @@ static int ssd16xx_write(const struct device *dev, const uint16_t x,
 		return -EINVAL;
 	}
 
-	buf_len = MIN(desc->buf_size, desc->height * desc->width / 8);
-	if (buf == NULL || buf_len == 0U) {
-		LOG_ERR("Display buffer is not available");
-		return -EINVAL;
-	}
-
 	if (desc->pitch > desc->width) {
 		LOG_ERR("Unsupported mode");
 		return -ENOTSUP;
@@ -320,6 +360,29 @@ static int ssd16xx_write(const struct device *dev, const uint16_t x,
 		return err;
 	}
 
+	return 0;
+}
+
+static int ssd16xx_write(const struct device *dev, const uint16_t x,
+			 const uint16_t y,
+			 const struct display_buffer_descriptor *desc,
+			 const void *buf)
+{
+	const struct ssd16xx_data *data = dev->data;
+	const size_t buf_len = MIN(desc->buf_size,
+				   desc->height * desc->width / 8);
+	int err;
+
+	if (buf == NULL || buf_len == 0U) {
+		LOG_ERR("Display buffer is not available");
+		return -EINVAL;
+	}
+
+	err = ssd16xx_set_window(dev, x, y, desc);
+	if (err < 0) {
+		return err;
+	}
+
 	err = ssd16xx_write_cmd(dev, SSD16XX_CMD_WRITE_RAM, (uint8_t *)buf,
 				buf_len);
 	if (err < 0) {
@@ -336,13 +399,65 @@ static int ssd16xx_write(const struct device *dev, const uint16_t x,
 	return 0;
 }
 
-static int ssd16xx_read(const struct device *dev, const uint16_t x,
-			const uint16_t y,
+int ssd16xx_read_ram(const struct device *dev, enum ssd16xx_ram ram_type,
+		     const uint16_t x, const uint16_t y,
+		     const struct display_buffer_descriptor *desc,
+		     void *buf)
+{
+	const struct ssd16xx_data *data = dev->data;
+	const size_t buf_len = MIN(desc->buf_size,
+				   desc->height * desc->width / 8);
+	int err;
+	uint8_t ram_ctrl;
+
+	if (!data->read_supported) {
+		return -ENOTSUP;
+	}
+
+	switch (ram_type) {
+	case SSD16XX_RAM_BLACK:
+		ram_ctrl = SSD16XX_RAM_READ_CTRL_BLACK;
+		break;
+
+	case SSD16XX_RAM_RED:
+		ram_ctrl = SSD16XX_RAM_READ_CTRL_RED;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	if (buf == NULL || buf_len == 0U) {
+		LOG_ERR("Display buffer is not available");
+		return -EINVAL;
+	}
+
+	err = ssd16xx_set_window(dev, x, y, desc);
+	if (err < 0) {
+		return err;
+	}
+
+	err = ssd16xx_write_cmd(dev, SSD16XX_CMD_RAM_READ_CTRL,
+				&ram_ctrl, sizeof(ram_ctrl));
+	if (err < 0) {
+		return err;
+	}
+
+	err = ssd16xx_read_cmd(dev, SSD16XX_CMD_READ_RAM, (uint8_t *)buf,
+			       buf_len);
+	if (err < 0) {
+		return err;
+	}
+
+	return 0;
+}
+
+static int ssd16xx_read(const struct device *dev,
+			const uint16_t x, const uint16_t y,
 			const struct display_buffer_descriptor *desc,
 			void *buf)
 {
-	LOG_ERR("not supported");
-	return -ENOTSUP;
+	return ssd16xx_read_ram(dev, SSD16XX_RAM_BLACK, x, y, desc, buf);
 }
 
 static void *ssd16xx_get_framebuffer(const struct device *dev)
@@ -674,6 +789,7 @@ static int ssd16xx_controller_init(const struct device *dev)
 static int ssd16xx_init(const struct device *dev)
 {
 	const struct ssd16xx_config *config = dev->config;
+	struct ssd16xx_data *data = dev->data;
 	int err;
 
 	LOG_DBG("");
@@ -683,6 +799,9 @@ static int ssd16xx_init(const struct device *dev)
 		return -ENODEV;
 	}
 
+	data->read_supported =
+		(config->bus.config.operation & SPI_HALF_DUPLEX) != 0;
+
 	if (!device_is_ready(config->reset_gpio.port)) {
 		LOG_ERR("Reset GPIO device not ready");
 		return -ENODEV;

drivers/display/ssd16xx_regs.h

@@ -19,15 +19,20 @@
 #define SSD16XX_CMD_SW_RESET			0x12
 #define SSD16XX_CMD_TSENSOR_SELECTION		0x18
 #define SSD16XX_CMD_TSENS_CTRL			0x1a
+#define SSD16XX_CMD_READ_TSENS_CTRL		0x1b
 #define SSD16XX_CMD_MASTER_ACTIVATION		0x20
 #define SSD16XX_CMD_UPDATE_CTRL1		0x21
 #define SSD16XX_CMD_UPDATE_CTRL2		0x22
 #define SSD16XX_CMD_WRITE_RAM			0x24
 #define SSD16XX_CMD_WRITE_RED_RAM		0x26
+#define SSD16XX_CMD_READ_RAM			0x27
 #define SSD16XX_CMD_VCOM_SENSE			0x28
 #define SSD16XX_CMD_VCOM_SENSE_DURATON		0x29
 #define SSD16XX_CMD_PRGM_VCOM_OTP		0x2a
 #define SSD16XX_CMD_VCOM_VOLTAGE		0x2c
+#define SSD16XX_CMD_READ_OTP_REG		0x2d
+#define SSD16XX_CMD_READ_USER_ID		0x2e
+#define SSD16XX_CMD_READ_STATUS			0x2f
 #define SSD16XX_CMD_PRGM_WS_OTP			0x30
 #define SSD16XX_CMD_LOAD_WS_OTP			0x31
 #define SSD16XX_CMD_UPDATE_LUT			0x32
@@ -36,6 +41,7 @@
 #define SSD16XX_CMD_DUMMY_LINE			0x3a
 #define SSD16XX_CMD_GATE_LINE_WIDTH		0x3b
 #define SSD16XX_CMD_BWF_CTRL			0x3c
+#define SSD16XX_CMD_RAM_READ_CTRL		0x41
 #define SSD16XX_CMD_RAM_XPOS_CTRL		0x44
 #define SSD16XX_CMD_RAM_YPOS_CTRL		0x45
 #define SSD16XX_CMD_RAM_XPOS_CNTR		0x4e
@@ -71,6 +77,9 @@
 #define SSD16XX_SLEEP_MODE_DSM			0x01
 #define SSD16XX_SLEEP_MODE_PON			0x00
 
+#define SSD16XX_RAM_READ_CTRL_BLACK		0
+#define SSD16XX_RAM_READ_CTRL_RED		1
+
 /* Default values */
 #define SSD16XX_VAL_DUMMY_LINE			0x1a
 #define SSD16XX_VAL_GATE_LWIDTH			0x08

include/zephyr/display/ssd16xx.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2022 Andreas Sandberg
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DISPLAY_SSD16XX_H_
+#define ZEPHYR_INCLUDE_DISPLAY_SSD16XX_H_
+
+#include <zephyr/drivers/display.h>
+
+/**
+ * SSD16xx RAM type for direct RAM access
+ */
+enum ssd16xx_ram {
+	/** The black RAM buffer. This is typically the buffer used to
+	 * compose the contents that will be displayed after the next
+	 * refresh.
+	 */
+	SSD16XX_RAM_BLACK = 0,
+	/* The red RAM buffer. This is typically the old frame buffer
+	 * when performing partial refreshes or an additional color
+	 * channel.
+	 */
+	SSD16XX_RAM_RED,
+};
+
+/**
+ * @brief Read data directly from the display controller's internal
+ * RAM.
+ *
+ * @param dev Pointer to device structure
+ * @param ram_type Type of RAM to read from
+ * @param x Coordinate relative to the upper left corner
+ * @param y Coordinate relative to the upper left corner
+ * @param desc Structure describing the buffer layout
+ * @param buf Output buffer
+ *
+ * @retval 0 on success, negative errno on failure.
+ */
+int ssd16xx_read_ram(const struct device *dev, enum ssd16xx_ram ram_type,
+		     const uint16_t x, const uint16_t y,
+		     const struct display_buffer_descriptor *desc,
+		     void *buf);
+
+#endif /* ZEPHYR_INCLUDE_DISPLAY_SSD16XX_H_ */