drivers: flash: stm32: add STM32 option bytes extended ops

Add two new flash extended operations for reading and writing STM32 option bytes from the application code. Signed-off-by: Fabio Baltieri <[email protected]>
zephyrproject-rtos · Nov 29, 2024 · fe5f9d5 · fe5f9d5
1 parent 4e66317
commit fe5f9d5
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Showing 8 changed files with 108 additions and 17 deletions.
diff --git a/drivers/flash/Kconfig.stm32 b/drivers/flash/Kconfig.stm32
@@ -84,6 +84,14 @@ config FLASH_STM32_BLOCK_REGISTERS
 	  registers improves system security, because flash content (or
 	  protection settings) can't be changed even when exploit was found.
 
+config FLASH_STM32_OPTION_BYTES
+	bool "Extended operation for option bytes access"
+	select FLASH_HAS_EX_OP
+	default n
+	help
+	  Enables flash extended operations that can be used to write and write
+	  STM32 option bytes.
+
 config USE_MICROCHIP_QSPI_FLASH_WITH_STM32
 	bool "Include patch for Microchip qspi flash when running with stm32"
 	depends on DT_HAS_ST_STM32_QSPI_NOR_ENABLED

diff --git a/drivers/flash/flash_stm32.c b/drivers/flash/flash_stm32.c
@@ -486,6 +486,41 @@ static int flash_stm32_ex_op(const struct device *dev, uint16_t code,
 		rv = flash_stm32_control_register_disable(dev);
 		break;
 #endif /* CONFIG_FLASH_STM32_BLOCK_REGISTERS */
+#if defined(CONFIG_FLASH_STM32_OPTION_BYTES) && ( \
+		defined(CONFIG_DT_HAS_ST_STM32F4_FLASH_CONTROLLER_ENABLED) || \
+		defined(CONFIG_DT_HAS_ST_STM32F7_FLASH_CONTROLLER_ENABLED) || \
+		defined(CONFIG_DT_HAS_ST_STM32G4_FLASH_CONTROLLER_ENABLED) || \
+		defined(CONFIG_DT_HAS_ST_STM32L4_FLASH_CONTROLLER_ENABLED))
+	case FLASH_STM32_EX_OP_OPTB_READ:
+		if (out == NULL) {
+			rv = -EINVAL;
+			break;
+		}
+
+		*(uint32_t *)out = flash_stm32_option_bytes_read(dev);
+		rv = 0;
+
+		break;
+	case FLASH_STM32_EX_OP_OPTB_WRITE:
+		int rv2;
+
+		rv = flash_stm32_option_bytes_lock(dev, false);
+		if (rv > 0) {
+			break;
+		}
+
+		rv2 = flash_stm32_option_bytes_write(dev, UINT32_MAX, (uint32_t)in);
+		/* returned later, we always re-lock */
+
+		rv = flash_stm32_option_bytes_lock(dev, true);
+		if (rv > 0) {
+			break;
+		}
+
+		rv = rv2;
+
+		break;
+#endif
 	}
 
 	flash_stm32_sem_give(dev);

diff --git a/drivers/flash/flash_stm32.h b/drivers/flash/flash_stm32.h
@@ -291,6 +291,11 @@ int flash_stm32_wait_flash_idle(const struct device *dev);
 
 int flash_stm32_option_bytes_lock(const struct device *dev, bool enable);
 
+uint32_t flash_stm32_option_bytes_read(const struct device *dev);
+
+int flash_stm32_option_bytes_write(const struct device *dev, uint32_t mask,
+				   uint32_t value);
+
 #ifdef CONFIG_SOC_SERIES_STM32WBX
 int flash_stm32_check_status(const struct device *dev);
 #endif /* CONFIG_SOC_SERIES_STM32WBX */

diff --git a/drivers/flash/flash_stm32f4x.c b/drivers/flash/flash_stm32f4x.c
@@ -231,8 +231,8 @@ int flash_stm32_write_range(const struct device *dev, unsigned int offset,
 	return rc;
 }
 
-static __unused int write_optb(const struct device *dev, uint32_t mask,
-			       uint32_t value)
+int flash_stm32_option_bytes_write(const struct device *dev, uint32_t mask,
+				   uint32_t value)
 {
 	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
 	int rc;
@@ -264,6 +264,13 @@ static __unused int write_optb(const struct device *dev, uint32_t mask,
 	return 0;
 }
 
+uint32_t flash_stm32_option_bytes_read(const struct device *dev)
+{
+	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
+
+	return regs->OPTCR;
+}
+
 #if defined(CONFIG_FLASH_STM32_WRITE_PROTECT)
 int flash_stm32_update_wp_sectors(const struct device *dev,
 				  uint32_t changed_sectors,
@@ -279,7 +286,8 @@ int flash_stm32_update_wp_sectors(const struct device *dev,
 	/* Sector is protected when bit == 0. Flip protected_sectors bits */
 	protected_sectors = ~protected_sectors & changed_sectors;
 
-	return write_optb(dev, changed_sectors, protected_sectors);
+	return flash_stm32_option_bytes_write(dev, changed_sectors,
+					      protected_sectors);
 }
 
 int flash_stm32_get_wp_sectors(const struct device *dev,
@@ -304,8 +312,8 @@ uint8_t flash_stm32_get_rdp_level(const struct device *dev)
 
 void flash_stm32_set_rdp_level(const struct device *dev, uint8_t level)
 {
-	write_optb(dev, FLASH_OPTCR_RDP_Msk,
-		(uint32_t)level << FLASH_OPTCR_RDP_Pos);
+	flash_stm32_option_bytes_write(dev, FLASH_OPTCR_RDP_Msk,
+				       (uint32_t)level << FLASH_OPTCR_RDP_Pos);
 }
 #endif /* CONFIG_FLASH_STM32_READOUT_PROTECTION */
 

diff --git a/drivers/flash/flash_stm32f7x.c b/drivers/flash/flash_stm32f7x.c
@@ -159,8 +159,8 @@ int flash_stm32_write_range(const struct device *dev, unsigned int offset,
 	return rc;
 }
 
-static __unused int write_optb(const struct device *dev, uint32_t mask,
-			       uint32_t value)
+int flash_stm32_option_bytes_write(const struct device *dev, uint32_t mask,
+				   uint32_t value)
 {
 	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
 	int rc;
@@ -187,6 +187,13 @@ static __unused int write_optb(const struct device *dev, uint32_t mask,
 	return flash_stm32_wait_flash_idle(dev);
 }
 
+uint32_t flash_stm32_option_bytes_read(const struct device *dev)
+{
+	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
+
+	return regs->OPTCR;
+}
+
 #if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION)
 uint8_t flash_stm32_get_rdp_level(const struct device *dev)
 {
@@ -197,8 +204,8 @@ uint8_t flash_stm32_get_rdp_level(const struct device *dev)
 
 void flash_stm32_set_rdp_level(const struct device *dev, uint8_t level)
 {
-	write_optb(dev, FLASH_OPTCR_RDP_Msk,
-		(uint32_t)level << FLASH_OPTCR_RDP_Pos);
+	flash_stm32_option_bytes_write(dev, FLASH_OPTCR_RDP_Msk,
+				       (uint32_t)level << FLASH_OPTCR_RDP_Pos);
 }
 #endif /* CONFIG_FLASH_STM32_READOUT_PROTECTION */
 

diff --git a/drivers/flash/flash_stm32g4x.c b/drivers/flash/flash_stm32g4x.c
@@ -255,8 +255,8 @@ int flash_stm32_write_range(const struct device *dev, unsigned int offset,
 	return rc;
 }
 
-static __unused int write_optb(const struct device *dev, uint32_t mask,
-			       uint32_t value)
+int flash_stm32_option_bytes_write(const struct device *dev, uint32_t mask,
+				   uint32_t value)
 {
 	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
 	int rc;
@@ -288,6 +288,13 @@ static __unused int write_optb(const struct device *dev, uint32_t mask,
 	return 0;
 }
 
+uint32_t flash_stm32_option_bytes_read(const struct device *dev)
+{
+	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
+
+	return regs->OPTR;
+}
+
 #if defined(CONFIG_FLASH_STM32_WRITE_PROTECT)
 
 /*
@@ -314,8 +321,8 @@ uint8_t flash_stm32_get_rdp_level(const struct device *dev)
 
 void flash_stm32_set_rdp_level(const struct device *dev, uint8_t level)
 {
-	write_optb(dev, FLASH_OPTR_RDP_Msk,
-		(uint32_t)level << FLASH_OPTR_RDP_Pos);
+	flash_stm32_option_bytes_write(dev, FLASH_OPTR_RDP_Msk,
+				       (uint32_t)level << FLASH_OPTR_RDP_Pos);
 }
 #endif /* CONFIG_FLASH_STM32_READOUT_PROTECTION */
 

diff --git a/drivers/flash/flash_stm32l4x.c b/drivers/flash/flash_stm32l4x.c
@@ -246,8 +246,8 @@ int flash_stm32_write_range(const struct device *dev, unsigned int offset,
 	return rc;
 }
 
-static __unused int write_optb(const struct device *dev, uint32_t mask,
-			       uint32_t value)
+int flash_stm32_option_bytes_write(const struct device *dev, uint32_t mask,
+				   uint32_t value)
 {
 	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
 	int rc;
@@ -279,6 +279,13 @@ static __unused int write_optb(const struct device *dev, uint32_t mask,
 	return 0;
 }
 
+uint32_t flash_stm32_option_bytes_read(const struct device *dev)
+{
+	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
+
+	return regs->OPTR;
+}
+
 #if defined(CONFIG_FLASH_STM32_WRITE_PROTECT)
 
 /*
@@ -305,8 +312,8 @@ uint8_t flash_stm32_get_rdp_level(const struct device *dev)
 
 void flash_stm32_set_rdp_level(const struct device *dev, uint8_t level)
 {
-	write_optb(dev, FLASH_OPTR_RDP_Msk,
-		(uint32_t)level << FLASH_OPTR_RDP_Pos);
+	flash_stm32_option_bytes_write(dev, FLASH_OPTR_RDP_Msk,
+				       (uint32_t)level << FLASH_OPTR_RDP_Pos);
 }
 #endif /* CONFIG_FLASH_STM32_READOUT_PROTECTION */
 

diff --git a/include/zephyr/drivers/flash/stm32_flash_api_extensions.h b/include/zephyr/drivers/flash/stm32_flash_api_extensions.h
@@ -48,6 +48,20 @@ enum stm32_ex_ops {
 	 * erasing or writing.
 	 */
 	FLASH_STM32_EX_OP_BLOCK_CONTROL_REG,
+	/*
+	 * STM32 option bytes read.
+	 *
+	 * Read the option bytes content, out takes a *uint32_t, in is unused.
+	 */
+	FLASH_STM32_EX_OP_OPTB_READ,
+	/*
+	 * STM32 option bytes write.
+	 *
+	 * Write the option bytes content, in takes the new value, out is
+	 * unused. Note that the new value only takes effect after the device
+	 * is restarted.
+	 */
+	FLASH_STM32_EX_OP_OPTB_WRITE,
 };
 
 #if defined(CONFIG_FLASH_STM32_WRITE_PROTECT)