Add support for Microchip QSPI NOR flash to STM32 OSPI and XSPI drivers

drivers/flash/flash_stm32_ospi.c

@@ -707,6 +707,32 @@ static int stm32_ospi_write_enable(struct flash_stm32_ospi_data *dev_data,
 	return stm32_ospi_wait_auto_polling(dev_data, &s_config, HAL_OSPI_TIMEOUT_DEFAULT_VALUE);
 }
 
+static int ospi_write_unprotect(const struct device *dev)
+{
+	struct flash_stm32_ospi_data *dev_data = dev->data;
+	int ret = 0;
+
+	/* This is a SPI/STR command to issue to the external Flash device */
+	OSPI_RegularCmdTypeDef cmd_unprotect = ospi_prepare_cmd(OSPI_SPI_MODE, OSPI_STR_TRANSFER);
+
+	cmd_unprotect.Instruction = SPI_NOR_CMD_ULBPR;
+	cmd_unprotect.InstructionMode = HAL_OSPI_INSTRUCTION_1_LINE;
+	cmd_unprotect.AddressMode = HAL_OSPI_ADDRESS_NONE;
+	cmd_unprotect.DataMode    = HAL_OSPI_DATA_NONE;
+
+	if (IS_ENABLED(DT_INST_PROP(0, requires_ulbpr))) {
+		ret = stm32_ospi_write_enable(dev_data, OSPI_SPI_MODE, OSPI_STR_TRANSFER);
+
+		if (ret != 0) {
+			return ret;
+		}
+
+		ret = ospi_send_cmd(dev, &cmd_unprotect);
+	}
+
+	return ret;
+}
+
 /* Write Flash configuration register 2 with new dummy cycles */
 static int stm32_ospi_write_cfg2reg_dummy(OSPI_HandleTypeDef *hospi,
 					uint8_t nor_mode, uint8_t nor_rate)
@@ -2569,6 +2595,13 @@ static int flash_stm32_ospi_init(const struct device *dev)
 	}
 #endif /* CONFIG_FLASH_PAGE_LAYOUT */
 
+	ret = ospi_write_unprotect(dev);
+	if (ret != 0) {
+		LOG_ERR("write unprotect failed: %d", ret);
+		return -ENODEV;
+	}
+	LOG_DBG("Write Un-protected");
+
 #ifdef CONFIG_STM32_MEMMAP
 	/* Now configure the octo Flash in MemoryMapped (access by address) */
 	ret = stm32_ospi_set_memorymap(dev);

drivers/flash/flash_stm32_xspi.c

@@ -567,6 +567,31 @@ static int stm32_xspi_write_enable(const struct device *dev,
 	return stm32_xspi_wait_auto_polling(dev, &s_config, HAL_XSPI_TIMEOUT_DEFAULT_VALUE);
 }
 
+static int xspi_write_unprotect(const struct device *dev)
+{
+	int ret = 0;
+
+	/* This is a SPI/STR command to issue to the external Flash device */
+	XSPI_RegularCmdTypeDef cmd_unprotect = xspi_prepare_cmd(XSPI_SPI_MODE, XSPI_STR_TRANSFER);
+
+	cmd_unprotect.Instruction = SPI_NOR_CMD_ULBPR;
+	cmd_unprotect.InstructionMode = HAL_XSPI_INSTRUCTION_1_LINE;
+	cmd_unprotect.AddressMode = HAL_XSPI_ADDRESS_NONE;
+	cmd_unprotect.DataMode    = HAL_XSPI_DATA_NONE;
+
+	if (IS_ENABLED(DT_INST_PROP(0, requires_ulbpr))) {
+		ret = stm32_xspi_write_enable(dev, XSPI_SPI_MODE, XSPI_STR_TRANSFER);
+
+		if (ret != 0) {
+			return ret;
+		}
+
+		ret = xspi_send_cmd(dev, &cmd_unprotect);
+	}
+
+	return ret;
+}
+
 /* Write Flash configuration register 2 with new dummy cycles */
 static int stm32_xspi_write_cfg2reg_dummy(const struct device *dev,
 					uint8_t nor_mode, uint8_t nor_rate)
@@ -2372,6 +2397,13 @@ static int flash_stm32_xspi_init(const struct device *dev)
 	}
 #endif /* CONFIG_FLASH_PAGE_LAYOUT */
 
+	ret = xspi_write_unprotect(dev);
+	if (ret != 0) {
+		LOG_ERR("write unprotect failed: %d", ret);
+		return -ENODEV;
+	}
+	LOG_DBG("Write Un-protected");
+
 #ifdef CONFIG_STM32_MEMMAP
 	ret = stm32_xspi_set_memorymap(dev);
 	if (ret != 0) {

dts/bindings/flash_controller/st,stm32-ospi-nor.yaml

@@ -109,3 +109,12 @@ properties:
       * 2READ 1-2-2 (0xBB) -> 2READ 1-2-2 4B (0xBC)
       * QREAD 1-1-4 (0x6B) -> QREAD 1-1-4 4B (0x6C)
       * 4READ 1-4-4 (0xEB) -> 4READ 1-4-4 4B (0xEC)
+  requires-ulbpr:
+    type: boolean
+    description: |
+      Indicates the device requires the ULBPR (0x98) command.
+
+      Some flash chips such as the Microchip SST26VF series have a block
+      protection register that initializes to write-protected. Use this
+      property to indicate that the BPR must be unlocked before write
+      operations can proceed.