WIP: Cache and dump boot registers

This is the first step in exposing the FW-supplied DT.

mkknlimg or equivalent also needs to be run for this to get a DT rather
than ATAGS. Hopefully we'll find a way to build that directly into the
U-Boot image to avoid reliance on external tools.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>

board/raspberrypi/rpi/rpi.c

@@ -255,6 +255,21 @@ static struct mm_region bcm2837_mem_map[] = {
 struct mm_region *mem_map = bcm2837_mem_map;
 #endif
 
+static uint32_t boot_r0 __attribute__ ((section(".data")));
+static uint32_t boot_r1 __attribute__ ((section(".data")));
+static uint32_t boot_r2 __attribute__ ((section(".data")));
+static uint32_t boot_r3 __attribute__ ((section(".data")));
+
+void save_boot_params_ret(void);
+void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
+{
+	boot_r0 = r0;
+	boot_r1 = r1;
+	boot_r2 = r2;
+	boot_r3 = r3;
+	save_boot_params_ret();
+}
+
 int dram_init(void)
 {
 	ALLOC_CACHE_ALIGN_BUFFER(struct msg_get_arm_mem, msg, 1);
@@ -274,6 +289,13 @@ int dram_init(void)
 	return 0;
 }
 
+ulong board_get_usable_ram_top(ulong total_size)
+{
+	if ((gd->ram_top - boot_r2) > SZ_64M)
+		return gd->ram_top;
+	return boot_r2 & 0xffff0000;
+}
+
 static void set_fdtfile(void)
 {
 	const char *fdtfile;
@@ -441,6 +463,7 @@ static void get_board_rev(void)
 	}
 
 	printf("RPI %s (0x%x)\n", model->name, revision);
+	printf("boot regs: 0x%08x 0x%08x 0x%08x 0x%08x\n", boot_r0, boot_r1, boot_r2, boot_r3);
 }
 
 int board_init(void)