board: siemens: iot2050: Pass DDR size from FSBL

Due to new DDR size introduction, the current logic of determining the
DDR size is not able to get the correct size.

Instead, the DDR size is determined by the FSBL(SEBOOT) then passed to
u-boot through the scratchpad info.

The SEBoot version must be >= D/V01.04.01.02 to support this change.

Also now for some variants, the DDR size may > 2GB, so borrow some code
from the TI evm to iot2050 to support more than 2GB DDR.

Signed-off-by: Baocheng Su <baocheng.su@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

board/siemens/iot2050/board.c

@@ -38,6 +38,8 @@ struct iot2050_info {
 	u8 mac_addr_cnt;
 	u8 mac_addr[8][ARP_HLEN];
 	char seboot_version[40 + 1];
+	u8 padding[3];
+	u32 ddr_size_mb;
 } __packed;
 
 /*
@@ -341,18 +343,34 @@ int board_init(void)
 
 int dram_init(void)
 {
-	if (board_is_advanced())
+	struct iot2050_info *info = IOT2050_INFO_DATA;
-		gd->ram_size = SZ_2G;
+	gd->ram_size = ((phys_size_t)(info->ddr_size_mb)) << 20;
-	else
-		gd->ram_size = SZ_1G;
 
 	return 0;
 }
 
+ulong board_get_usable_ram_top(ulong total_size)
+{
+	/* Limit RAM used by U-Boot to the DDR low region */
+	if (gd->ram_top > 0x100000000)
+		return 0x100000000;
+
+	return gd->ram_top;
+}
+
 int dram_init_banksize(void)
 {
 	dram_init();
 
+	if (gd->ram_size > SZ_2G) {
+		/* Bank 0 declares the memory available in the DDR low region */
+		gd->bd->bi_dram[0].start = CFG_SYS_SDRAM_BASE;
+		gd->bd->bi_dram[0].size = SZ_2G;
+
+		/* Bank 1 declares the memory available in the DDR high region */
+		gd->bd->bi_dram[1].start = CFG_SYS_SDRAM_BASE1;
+		gd->bd->bi_dram[1].size = gd->ram_size - SZ_2G;
+	} else {
 		/* Bank 0 declares the memory available in the DDR low region */
 		gd->bd->bi_dram[0].start = CFG_SYS_SDRAM_BASE;
 		gd->bd->bi_dram[0].size = gd->ram_size;
@@ -360,6 +378,7 @@ int dram_init_banksize(void)
 		/* Bank 1 declares the memory available in the DDR high region */
 		gd->bd->bi_dram[1].start = 0;
 		gd->bd->bi_dram[1].size = 0;
+	}
 
 	return 0;
 }

doc/board/siemens/iot2050.rst

@@ -29,6 +29,9 @@ The following binaries from that source need to be present in the build folder:
  - seboot_pg1.bin
  - seboot_pg2.bin
 
+Note that SE-Boot D/V01.04.01.02 or greater is required, otherwise the DDR size
+will not be picked up correctly by U-Boot.
+
 When using the watchdog, a related firmware for the R5 core(s) is needed, e.g.
 https://github.com/siemens/k3-rti-wdt. The name and location of the image is
 configured via CONFIG_WDT_K3_RTI_FW_FILE.

include/configs/iot2050.h

@@ -24,6 +24,9 @@
 	func(USB, usb, 2)
 #endif
 
+/* DDR Configuration */
+#define CFG_SYS_SDRAM_BASE1		0x880000000
+
 /*
  * This defines all MMC devices, even if the basic variant has no mmc1.
  * The non-supported device will be removed from the boot targets during