qspi: stm32: Add code to switch flash memory to use 4 SIO pins

For proper operation of QUADSPI IP block, both sides of communication;
NOR flash memory and STM32 controller need to support 4 IO
transmission.

After this change the QSPI stm32 driver is able to program NOR flash
memory to switch itself to use all 4 IO lines (SIO[0123]) to transmit
and receive data.

The QE bit (in SPI-NOR's Status Register) is the non-volatile one, so
setting it is done only once (at first boot of the device).

Signed-off-by: Lukasz Majewski <lukma@denx.de>

drivers/flash/flash_stm32_qspi.c

@@ -90,6 +90,10 @@ struct flash_stm32_qspi_data {
 	 * 24-bit addresses.
 	 */
 	bool flag_access_32bit: 1;
+	/*
+	 * If set IO operations will be perfromed on SIO[0123] pins
+	 */
+	bool flag_quad_io_en: 1;
 };
 
 #define DEV_NAME(dev) ((dev)->name)
@@ -665,6 +669,101 @@ static int qspi_program_addr_4b(const struct device *dev)
 	return ret;
 }
 
+static int qspi_read_status_register(const struct device *dev, uint8_t *reg)
+{
+	QSPI_CommandTypeDef cmd = {
+		.Instruction = SPI_NOR_CMD_RDSR,
+		.InstructionMode = QSPI_INSTRUCTION_1_LINE,
+		.DataMode = QSPI_DATA_1_LINE,
+	};
+
+	return qspi_read_access(dev, &cmd, reg, sizeof(*reg));
+}
+
+static int qspi_write_status_register(const struct device *dev, uint8_t reg)
+{
+	QSPI_CommandTypeDef cmd = {
+		.Instruction = SPI_NOR_CMD_WRSR,
+		.InstructionMode = QSPI_INSTRUCTION_1_LINE,
+		.DataMode = QSPI_DATA_1_LINE,
+	};
+
+	return qspi_write_access(dev, &cmd, &reg, sizeof(reg));
+}
+
+static int qspi_write_enable(const struct device *dev)
+{
+	uint8_t reg;
+	int ret;
+
+	QSPI_CommandTypeDef cmd_write_en = {
+		.Instruction = SPI_NOR_CMD_WREN,
+		.InstructionMode = QSPI_INSTRUCTION_1_LINE,
+	};
+
+	ret = qspi_send_cmd(dev, &cmd_write_en);
+	if (ret) {
+		return ret;
+	}
+
+	do {
+		ret = qspi_read_status_register(dev, &reg);
+	} while (!ret && !(reg & SPI_NOR_WEL_BIT));
+
+	return ret;
+}
+
+static int qspi_program_quad_io(const struct device *dev)
+{
+	struct flash_stm32_qspi_data *data = DEV_DATA(dev);
+	uint8_t reg;
+	int ret;
+
+	/* Check if QE bit setting is required */
+	ret = qspi_read_status_register(dev, &reg);
+	if (ret) {
+		return ret;
+	}
+
+	/* Quit early when QE bit is already set */
+	if (reg & SPI_NOR_QE_BIT) {
+		goto out;
+	}
+
+	ret = qspi_write_enable(dev);
+	if (ret) {
+		return ret;
+	}
+
+	reg |= SPI_NOR_QE_BIT;
+	ret = qspi_write_status_register(dev, reg);
+	if (ret) {
+		return ret;
+	}
+
+	ret = qspi_wait_until_ready(dev);
+	if (ret) {
+		return ret;
+	}
+
+	ret = qspi_read_status_register(dev, &reg);
+	if (ret) {
+		return ret;
+	}
+
+	/* Check if QE bit programming is finished */
+	if (!(reg & SPI_NOR_QE_BIT)) {
+		LOG_ERR("Quad Enable [QE] bit in status reg not set");
+		return -EIO;
+	}
+
+ out:
+	LOG_INF("Flash - QUAD mode enabled [SR:0x%02x]", reg);
+	data->flag_quad_io_en = true;
+
+	return ret;
+}
+
 static int spi_nor_process_bfp(const struct device *dev,
 			       const struct jesd216_param_header *php,
 			       const struct jesd216_bfp *bfp)
@@ -723,6 +822,8 @@ static int spi_nor_process_bfp(const struct device *dev,
 		}
 	}
 
+	qspi_program_quad_io(dev);
+
 	return 0;
 }
 

drivers/flash/spi_nor.h

@@ -14,6 +14,7 @@
 /* Status register bits */
 #define SPI_NOR_WIP_BIT         BIT(0)  /* Write in progress */
 #define SPI_NOR_WEL_BIT         BIT(1)  /* Write enable latch */
+#define SPI_NOR_QE_BIT          BIT(6)  /* Enable quad mode */
 
 /* Control register bits */
 #define SPI_NOR_4BYTE_BIT       BIT(5)  /* 4B addressing */