soc: st: stm32: h7rsxx: Fix MPU region for read-only id flash region

Set correct MPU memory type and size for the uniqe device id, package code
and ADC VREF/TS calibration read-only flash region.

REGION_IO_ATTR configures the MPU region to device-memory with RW access,
which is also used for the PERIPH region. To avoid complicating things
unnecessarily, we use this type instead of defining a new device-RO.

The size is reduced to 512 bytes, because RM0477 table 28 and chapter
5.3.12 state that this read-only flash area has a size of 512 bytes.

Signed-off-by: Thomas Decker <[email protected]>

Author: TD-JBL

soc/st/stm32/stm32h7rsx/mpu_regions.c

@@ -27,8 +27,8 @@ static const struct arm_mpu_region mpu_regions[] = {
 	/* Region 3 */
 	MPU_REGION_ENTRY("SRAM_0", CONFIG_SRAM_BASE_ADDRESS, REGION_RAM_ATTR(REGION_SRAM_SIZE)),
 
-	/* Region 4 - Ready only flash with unique device id */
-	MPU_REGION_ENTRY("ID", 0x08FFF800, REGION_FLASH_ATTR(REGION_2K)),
+	/* Region 4 - Ready only flash with unique device id, package code and VREF/TS calib*/
+	MPU_REGION_ENTRY("ID", 0x08FFF800, REGION_IO_ATTR(REGION_512B)),
 
 #if DT_NODE_HAS_STATUS_OKAY(DT_NODELABEL(mac))
 #define sram_eth_node DT_NODELABEL(sram2)