renesas_rz: RAM size auto-detection

- Code now iterates through RAM at 512kB intervals to detect the supported OCRAM for a given CPU.

src/target/renesas_rz.c

@@ -73,11 +73,16 @@
  * except for pnrs stored in 'FIXED_PNR1', where the code is stored in reverse order (but the last 3 bytes are still 0x20 aka ' ')
  */
 
-/* Base address and size for the 4 OCRAM regions + their mirrors (includes RETRAM) */
+/* Base address for the RZ-series, including mirror */
 #define RENESAS_OCRAM_BASE        0x20000000U
 #define RENESAS_OCRAM_MIRROR_BASE 0x60000000U
-#define RENESAS_OCRAM_SIZE        0x00200000U
-#define RENESAS_OCRAM_SIZE_A1L    0x00300000U
+
+/* Maximum known OCRAM size for the RZ series (10MB on the RZ/A1H?) */
+#define RENESAS_OCRAM_MAX_SIZE 0x00a00000U
+
+/* RAM scanning increment (512k default to speed things up) */
+#define RENESAS_OCRAM_SCAN_INCREMENT 0x00080000U
+
 /* Base address and max size for the SPI Flash XIP region */
 #define RENESAS_SPI_FLASH_BASE 0x18000000U
 #define RENESAS_SPI_FLASH_SIZE 0x04000000U
@@ -140,7 +145,7 @@
 #define ID_RZ_A1 0x012U
 
 static const char *renesas_rz_part_name(uint32_t part_id);
-static uint32_t renesas_rz_ram_size(const uint32_t part_id);
+static uint32_t renesas_rz_ram_size(target_s *target);
 static bool renesas_rz_flash_prepare(target_s *target);
 static bool renesas_rz_flash_resume(target_s *target);
 static void renesas_rz_spi_read(target_s *target, uint16_t command, target_addr_t address, void *buffer, size_t length);
@@ -185,8 +190,10 @@ bool renesas_rz_probe(target_s *const target)
 	if (boot_mode == RENESAS_BSCAN_BOOT_MODE_SPI)
 		renesas_rz_add_flash(target);
 
-	target_add_ram32(target, RENESAS_OCRAM_BASE, renesas_rz_ram_size(part_id));
-	target_add_ram32(target, RENESAS_OCRAM_MIRROR_BASE, renesas_rz_ram_size(part_id));
+	/* Determine RAM size by attempting to read in 512MB increments */
+	uint32_t ram_size = renesas_rz_ram_size(target);
+	target_add_ram32(target, RENESAS_OCRAM_BASE, ram_size);
+	target_add_ram32(target, RENESAS_OCRAM_MIRROR_BASE, ram_size);
 	return true;
 }
 
@@ -204,15 +211,19 @@ static const char *renesas_rz_part_name(const uint32_t part_id)
 	return "Unknown";
 }
 
-static uint32_t renesas_rz_ram_size(const uint32_t part_id)
+/*
+ * Function to read RAM incrementally to determine the size of it for the given model.
+ */
+static uint32_t renesas_rz_ram_size(target_s *target)
 {
-	switch (part_id) {
-	case RENESAS_BSCAN_BSID_RZ_A1L:
-		return RENESAS_OCRAM_SIZE_A1L;
-	case RENESAS_BSCAN_BSID_RZ_A1LU:
-		return RENESAS_OCRAM_SIZE_A1L;
+	uint32_t result = 0;
+	for (uint32_t addr = RENESAS_OCRAM_BASE; addr < RENESAS_OCRAM_BASE + RENESAS_OCRAM_MAX_SIZE;
+		 addr += RENESAS_OCRAM_SCAN_INCREMENT) {
+		/* Read ahead by one scan increment and if there's an error, return the current size. */
+		if (target_mem32_read(target, &result, addr + RENESAS_OCRAM_SCAN_INCREMENT - 8U, sizeof(result)))
+			return addr - RENESAS_OCRAM_BASE;
 	}
-	return RENESAS_OCRAM_SIZE;
+	return RENESAS_OCRAM_MAX_SIZE;
 }
 
 static bool renesas_rz_flash_prepare(target_s *const target)