On 7/11/25 9:35 AM, Magnus Damm wrote:
Hello Magnus,
sorry for the late reply.
Here's a hack that adds SDRAM setup code to the r7s72100 Genmai board.
Might be useful in case someone wants to boot Linux on the Genmai board.
Before merge a few unclear points remain:
- How to make best use of the on-chip SDRAM?
The U-Boot DTS currently has a node for the 10 MiB at 0x20000000
Also used by CONFIG_CUSTOM_SYS_INIT_SP_ADDR in renesas_rza1.config
Can we use SRAM for U-Boot and (optional) SDRAM for Linux ?
[...]
--- 0001/board/renesas/genmai/genmai.c
+++ work/board/renesas/genmai/genmai.c 2025-07-11 16:11:32.621707802 +0900
@@ -12,6 +12,16 @@
#define CS0WCR (RZA1_BCR_BASE + 0x28)
#define CS1BCR (RZA1_BCR_BASE + 0x08)
#define CS1WCR (RZA1_BCR_BASE + 0x2c)
+#define CS2BCR (RZA1_BCR_BASE + 0x0c)
+#define CS2WCR (RZA1_BCR_BASE + 0x30)
+#define CS3BCR (RZA1_BCR_BASE + 0x10)
+#define CS3WCR (RZA1_BCR_BASE + 0x34)
+#define SDCR (RZA1_BCR_BASE + 0x4c)
+#define RTCOR (RZA1_BCR_BASE + 0x58)
+#define RTCSR (RZA1_BCR_BASE + 0x50)
+
+#define SDRAM_MODE_CS2 0x3FFFD040 /* CS2: CAS=2, burst write, 16bit bus */
+#define SDRAM_MODE_CS3 0x3FFFE040 /* CS3: CAS=2, burst write, 16bit bus */
It would be good to convert this to 'memory' driver instead, see e.g.:
6d47598629f6 ("memory: stm32-fmc2-ebi: add STM32 FMC2 EBI controller
driver")
Hacking more of this memory mapping into board files does not scale well.
DECLARE_GLOBAL_DATA_PTR;
@@ -27,23 +37,101 @@ int board_init(void)
return 0;
}
-/*
- * The Genmai DT will most likely contain memory nodes describing the external
- * SDRAM memory connected to CS2 and CS3, however we do not yet have any code
- * in U-Boot to setup the memory controller. For now ignore DT and make use of
- * the RZ/A1H on-chip memory which is 10 MiB at CFG_SYS_SDRAM_BASE.
- */
+// nicked from pinctrl-rza1.c
Can this be configured using pinctrl-rza1.c , maybe once the 'memory'
driver which would configure the chipselects is in place ?
[...]
The external memory (DRAM) could even be brought up using drivers/ram/
driver ?
