ram: renesas: Add Renesas R-Car Gen4 DBSC5 driver

Add Renesas R-Car Gen4 DBSC5 DRAM controller driver. This driver is currently
capable of bringing LPDDR5 DRAM on Renesas R-Car V4H Whitehawk board. Further
boards can be supported by supplying board specific DRAM configuration data
via dbsc5_get_board_data(). Support for R-Car V4M is not implemented, however
the driver is already mostly prepared to support this SoC.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/drivers/ram/renesas/dbsc5/dbsc5.h b/drivers/ram/renesas/dbsc5/dbsc5.h
new file mode 100644
index 0000000..c410eb0
--- /dev/null
+++ b/drivers/ram/renesas/dbsc5/dbsc5.h
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2024 Renesas Electronics Corp.
+ */
+
+#ifndef __DRIVERS_RAM_RENESAS_DBSC5_DBSC5_H__
+#define __DRIVERS_RAM_RENESAS_DBSC5_DBSC5_H__
+
+/*
+ * DBSC5 ... 0xe678_0000..0xe67fffff
+ * - AXMM_BASE		0xe6780000	MM (DDR Hier) MM AXI Router - Region 0
+ * - DBSC_A_BASE	0xe6790000	MM (DDR Hier) DBSC0A - Region 0
+ * - CCI_BASE		0xe67A0000	MM (DDR Hier) FBA for MM
+ * - DBSC_D_BASE	0xE67A4000	MM (DDR Hier) DBSC0D - Region 0
+ * - QOS_BASE		0xe67E0000	MM (DDR Hier) M-STATQ (64kiB)
+ */
+#define DBSC5_AXMM_OFFSET			0x00000
+#define DBSC5_DBSC_A_OFFSET			0x10000
+#define DBSC5_CCI_OFFSET			0x20000
+#define DBSC5_DBSC_D_OFFSET			0x24000
+#define DBSC5_QOS_OFFSET			0x60000
+
+struct renesas_dbsc5_data {
+	const char		*clock_node;
+	const char		*reset_node;
+};
+
+#endif /* __DRIVERS_RAM_RENESAS_DBSC5_DBSC5_H__ */