Implement readout protection for STM32F7

drivers/flash/Kconfig.stm32

@@ -50,7 +50,8 @@ config FLASH_STM32_WRITE_PROTECT_DISABLE_PREVENTION
 
 config FLASH_STM32_READOUT_PROTECTION
 	bool "Extended operation for flash readout protection control"
-	depends on SOC_SERIES_STM32F4X || SOC_SERIES_STM32L4X || SOC_SERIES_STM32G4X
+	depends on SOC_SERIES_STM32F4X || SOC_SERIES_STM32L4X || \
+			   SOC_SERIES_STM32G4X || SOC_SERIES_STM32F7X
 	select FLASH_HAS_EX_OP
 	default n
 	help

drivers/flash/flash_stm32.h

@@ -311,12 +311,9 @@ int flash_stm32_get_wp_sectors(const struct device *dev,
 			       uint32_t *protected_sectors);
 #endif
 #if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION)
+uint8_t flash_stm32_get_rdp_level(const struct device *dev);
 
-int flash_stm32_update_rdp(const struct device *dev, bool enable,
-			   bool permanent);
-
-int flash_stm32_get_rdp(const struct device *dev, bool *enabled,
-			bool *permanent);
+void flash_stm32_set_rdp_level(const struct device *dev, uint8_t level);
 #endif
 
 /* Flash extended operations */

drivers/flash/flash_stm32_ex_op.c

@@ -8,6 +8,7 @@
 #include <zephyr/device.h>
 #include <zephyr/drivers/flash/stm32_flash_api_extensions.h>
 #include <zephyr/kernel.h>
+#include <zephyr/logging/log.h>
 
 #ifdef CONFIG_USERSPACE
 #include <zephyr/syscall.h>
@@ -17,6 +18,8 @@
 #include <soc.h>
 #include "flash_stm32.h"
 
+LOG_MODULE_REGISTER(flash_stm32_ex_op, CONFIG_FLASH_LOG_LEVEL);
+
 #if defined(CONFIG_FLASH_STM32_WRITE_PROTECT)
 int flash_stm32_ex_op_sector_wp(const struct device *dev, const uintptr_t in,
 				void *out)
@@ -85,13 +88,79 @@ int flash_stm32_ex_op_sector_wp(const struct device *dev, const uintptr_t in,
 #endif /* CONFIG_FLASH_STM32_WRITE_PROTECT */
 
 #if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION)
+int flash_stm32_ex_op_update_rdp(const struct device *dev, bool enable,
+			   bool permanent)
+{
+	uint8_t current_level, target_level;
+
+	current_level = flash_stm32_get_rdp_level(dev);
+	target_level = current_level;
+
+	/*
+	 * 0xAA = RDP level 0 (no protection)
+	 * 0xCC = RDP level 2 (permanent protection)
+	 * others = RDP level 1 (protection active)
+	 */
+	switch (current_level) {
+	case FLASH_STM32_RDP2:
+		if (!enable || !permanent) {
+			LOG_DBG("RDP level 2 is permanent and can't be changed!");
+			return -ENOTSUP;
+		}
+		break;
+	case FLASH_STM32_RDP0:
+		if (enable) {
+			target_level = FLASH_STM32_RDP1;
+			if (permanent) {
+#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION_PERMANENT_ALLOW)
+				target_level = FLASH_STM32_RDP2;
+#else
+				LOG_DBG("Permanent readout protection (RDP "
+					"level 0 -> 2) not allowed");
+				return -ENOTSUP;
+#endif
+			}
+		}
+		break;
+	default: /* FLASH_STM32_RDP1 */
+		if (enable && permanent) {
+#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION_PERMANENT_ALLOW)
+			target_level = FLASH_STM32_RDP2;
+#else
+			LOG_DBG("Permanent readout protection (RDP "
+				"level 1 -> 2) not allowed");
+			return -ENOTSUP;
+#endif
+		}
+		if (!enable) {
+#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION_DISABLE_ALLOW)
+			target_level = FLASH_STM32_RDP0;
+#else
+			LOG_DBG("Disabling readout protection (RDP "
+				"level 1 -> 0) not allowed");
+			return -EACCES;
+#endif
+		}
+	}
+
+	/* Update RDP level if needed */
+	if (current_level != target_level) {
+		LOG_INF("RDP changed from 0x%02x to 0x%02x", current_level,
+			target_level);
+
+		flash_stm32_set_rdp_level(dev, target_level);
+	}
+	return 0;
+}
+
 int flash_stm32_ex_op_rdp(const struct device *dev, const uintptr_t in,
 			  void *out)
 {
 	const struct flash_stm32_ex_op_rdp *request =
 		(const struct flash_stm32_ex_op_rdp *)in;
 	struct flash_stm32_ex_op_rdp *result =
 		(struct flash_stm32_ex_op_rdp *)out;
+	uint8_t current_level;
 
 #ifdef CONFIG_USERSPACE
 	struct flash_stm32_ex_op_rdp copy;
@@ -108,7 +177,7 @@ int flash_stm32_ex_op_rdp(const struct device *dev, const uintptr_t in,
 #endif
 		rc = flash_stm32_option_bytes_lock(dev, false);
 		if (rc == 0) {
-			rc = flash_stm32_update_rdp(dev, request->enable,
+			rc = flash_stm32_ex_op_update_rdp(dev, request->enable,
 						    request->permanent);
 		}
 
@@ -124,10 +193,26 @@ int flash_stm32_ex_op_rdp(const struct device *dev, const uintptr_t in,
 			result = &copy;
 		}
 #endif
-		rc2 = flash_stm32_get_rdp(dev, &result->enable,
-					  &result->permanent);
-		if (!rc) {
-			rc = rc2;
+
+		current_level = flash_stm32_get_rdp_level(dev);
+
+		/*
+		 * 0xAA = RDP level 0 (no protection)
+		 * 0xCC = RDP level 2 (permanent protection)
+		 * others = RDP level 1 (protection active)
+		 */
+		switch (current_level) {
+		case FLASH_STM32_RDP2:
+			result->enable = true;
+			result->permanent = true;
+			break;
+		case FLASH_STM32_RDP0:
+			result->enable = false;
+			result->permanent = false;
+			break;
+		default: /* FLASH_STM32_RDP1 */
+			result->enable = true;
+			result->permanent = false;
 		}
 
 #ifdef CONFIG_USERSPACE

drivers/flash/flash_stm32f4x.c

@@ -295,102 +295,17 @@ int flash_stm32_get_wp_sectors(const struct device *dev,
 #endif /* CONFIG_FLASH_STM32_WRITE_PROTECT */
 
 #if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION)
-int flash_stm32_update_rdp(const struct device *dev, bool enable,
-			   bool permanent)
+uint8_t flash_stm32_get_rdp_level(const struct device *dev)
 {
 	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
-	uint8_t current_level, target_level;
 
-	current_level =
-		(regs->OPTCR & FLASH_OPTCR_RDP_Msk) >> FLASH_OPTCR_RDP_Pos;
-	target_level = current_level;
-
-	/*
-	 * 0xAA = RDP level 0 (no protection)
-	 * 0xCC = RDP level 2 (permanent protection)
-	 * others = RDP level 1 (protection active)
-	 */
-	switch (current_level) {
-	case FLASH_STM32_RDP2:
-		if (!enable || !permanent) {
-			LOG_ERR("RDP level 2 is permanent and can't be changed!");
-			return -ENOTSUP;
-		}
-		break;
-	case FLASH_STM32_RDP0:
-		if (enable) {
-			target_level = FLASH_STM32_RDP1;
-			if (permanent) {
-#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION_PERMANENT_ALLOW)
-				target_level = FLASH_STM32_RDP2;
-#else
-				LOG_ERR("Permanent readout protection (RDP "
-					"level 0 -> 2) not allowed");
-				return -ENOTSUP;
-#endif
-			}
-		}
-		break;
-	default: /* FLASH_STM32_RDP1 */
-		if (enable && permanent) {
-#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION_PERMANENT_ALLOW)
-			target_level = FLASH_STM32_RDP2;
-#else
-			LOG_ERR("Permanent readout protection (RDP "
-				"level 1 -> 2) not allowed");
-			return -ENOTSUP;
-#endif
-		}
-		if (!enable) {
-#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION_DISABLE_ALLOW)
-			target_level = FLASH_STM32_RDP0;
-#else
-			LOG_ERR("Disabling readout protection (RDP "
-				"level 1 -> 0) not allowed");
-			return -EACCES;
-#endif
-		}
-	}
-
-	/* Update RDP level if needed */
-	if (current_level != target_level) {
-		LOG_INF("RDP changed from 0x%02x to 0x%02x", current_level,
-			target_level);
-
-		write_optb(dev, FLASH_OPTCR_RDP_Msk,
-			   (uint32_t)target_level << FLASH_OPTCR_RDP_Pos);
-	}
-	return 0;
+	return (regs->OPTCR & FLASH_OPTCR_RDP_Msk) >> FLASH_OPTCR_RDP_Pos;
 }
 
-int flash_stm32_get_rdp(const struct device *dev, bool *enabled,
-			bool *permanent)
+void flash_stm32_set_rdp_level(const struct device *dev, uint8_t level)
 {
-	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
-	uint8_t current_level;
-
-	current_level =
-		(regs->OPTCR & FLASH_OPTCR_RDP_Msk) >> FLASH_OPTCR_RDP_Pos;
-
-	/*
-	 * 0xAA = RDP level 0 (no protection)
-	 * 0xCC = RDP level 2 (permanent protection)
-	 * others = RDP level 1 (protection active)
-	 */
-	switch (current_level) {
-	case FLASH_STM32_RDP2:
-		*enabled = true;
-		*permanent = true;
-		break;
-	case FLASH_STM32_RDP0:
-		*enabled = false;
-		*permanent = false;
-		break;
-	default: /* FLASH_STM32_RDP1 */
-		*enabled = true;
-		*permanent = false;
-	}
-	return 0;
+	write_optb(dev, FLASH_OPTCR_RDP_Msk,
+		(uint32_t)level << FLASH_OPTCR_RDP_Pos);
 }
 #endif /* CONFIG_FLASH_STM32_READOUT_PROTECTION */
 

drivers/flash/flash_stm32f7x.c

@@ -159,6 +159,48 @@ 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)
+{
+	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
+	int rc;
+
+	if (regs->OPTCR & FLASH_OPTCR_OPTLOCK) {
+		return -EIO;
+	}
+
+	if ((regs->OPTCR & mask) == value) {
+		return 0;
+	}
+
+	rc = flash_stm32_wait_flash_idle(dev);
+	if (rc < 0) {
+		return rc;
+	}
+
+	regs->OPTCR = (regs->OPTCR & ~mask) | value;
+	regs->OPTCR |= FLASH_OPTCR_OPTSTRT;
+
+	/* Make sure previous write is completed. */
+	barrier_dsync_fence_full();
+
+	return flash_stm32_wait_flash_idle(dev);
+}
+
+#if defined(CONFIG_FLASH_STM32_READOUT_PROTECTION)
+uint8_t flash_stm32_get_rdp_level(const struct device *dev)
+{
+	FLASH_TypeDef *regs = FLASH_STM32_REGS(dev);
+
+	return (regs->OPTCR & FLASH_OPTCR_RDP_Msk) >> FLASH_OPTCR_RDP_Pos;
+}
+
+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);
+}
+#endif /* CONFIG_FLASH_STM32_READOUT_PROTECTION */
 
 /* Some SoC can run in single or dual bank mode, others can't.
  * Different SoC flash layouts are specified in various reference