drivers: flash: stm32_{o|x}spi: Add ULBPR support

Commits 72370b2 and ff34d57 added the requires-ulbpr
(Unlock Block Protection Register) property to the devicetree binding
for devices controlled by the STM32 QSPI peripheral, and support for
this property to the STM32 QSPI driver.
Some QSPI flash ICs (e.g. Microchip SST26VF series) require this
command to be sent before writing/erasing is possible.

This commit adds the same support to the STM32 OSPI and XSPI drivers.

Signed-off-by: Ben Marsh <[email protected]>

Author: besmarsh

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.