arm: juno: Enable OF_CONTROL

The Arm Juno board was still somewhat stuck in "hardcoded land", even
though there are stable DTs around, and one happens to actually be on
the memory mapped NOR flash.

Enable the configuration options to let the board use OF_CONTROL, and
add a routine to find the address of the DTB partition in NOR
flash, to use that for U-Boot's own purposes.
This can also passed on via $fdtcontroladdr to any kernel or EFI
application, removing the need to actually load a device tree.

Since the existing "afs" command and its flash routines require
flash_init() to be called before being usable, and this is done much
later in the boot process, we introduce a stripped-down partition finder
routine in vexpress64.c, to scan the NOR flash partitions for the
DT partition. This location is then used for U-Boot to find and probe
devices.

The name of the partition can be configured, if needed, but defaults
to "board.dtb", which is used by Linaro's firmware image provided.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

2 files changed, 64 insertions, 0 deletions

diff --git a/board/armltd/vexpress64/Kconfig b/board/armltd/vexpress64/Kconfig
index 90144184334..1d13f542e67 100644
--- a/board/armltd/vexpress64/Kconfig
+++ b/board/armltd/vexpress64/Kconfig
@@ -9,4 +9,11 @@ config SYS_VENDOR
 config SYS_CONFIG_NAME
 	default "vexpress_aemv8a"
 
+config JUNO_DTB_PART
+	string "NOR flash partition holding DTB"
+	default "board.dtb"
+	help
+	  The ARM partition name in the NOR flash memory holding the
+	  device tree blob to configure U-Boot.
+
 endif
diff --git a/board/armltd/vexpress64/vexpress64.c b/board/armltd/vexpress64/vexpress64.c
index dd0ebdd3030..ba49b32e58c 100644
--- a/board/armltd/vexpress64/vexpress64.c
+++ b/board/armltd/vexpress64/vexpress64.c
@@ -82,6 +82,63 @@ int dram_init_banksize(void)
 	return 0;
 }
 
+#ifdef CONFIG_OF_BOARD
+#define JUNO_FLASH_SEC_SIZE	(256 * 1024)
+static phys_addr_t find_dtb_in_nor_flash(const char *partname)
+{
+	phys_addr_t sector = CONFIG_SYS_FLASH_BASE;
+	int i;
+
+	for (i = 0;
+	     i < CONFIG_SYS_MAX_FLASH_SECT;
+	     i++, sector += JUNO_FLASH_SEC_SIZE) {
+		int len = strlen(partname) + 1;
+		int offs;
+		phys_addr_t imginfo;
+		u32 reg;
+
+		reg = readl(sector + JUNO_FLASH_SEC_SIZE - 0x04);
+                /* This makes up the string "HSLFTOOF" flash footer */
+		if (reg != 0x464F4F54U)
+			continue;
+		reg = readl(sector + JUNO_FLASH_SEC_SIZE - 0x08);
+                if (reg != 0x464C5348U)
+			continue;
+
+		for (offs = 0; offs < 32; offs += 4, len -= 4) {
+			reg = readl(sector + JUNO_FLASH_SEC_SIZE - 0x30 + offs);
+			if (strncmp(partname + offs, (char *)&reg,
+			            len > 4 ? 4 : len))
+				break;
+
+			if (len > 4)
+				continue;
+
+			reg = readl(sector + JUNO_FLASH_SEC_SIZE - 0x10);
+			imginfo = sector + JUNO_FLASH_SEC_SIZE - 0x30 - reg;
+			reg = readl(imginfo + 0x54);
+
+			return CONFIG_SYS_FLASH_BASE +
+			       reg * JUNO_FLASH_SEC_SIZE;
+		}
+	}
+
+	printf("No DTB found\n");
+
+	return ~0;
+}
+
+void *board_fdt_blob_setup(void)
+{
+	phys_addr_t fdt_rom_addr = find_dtb_in_nor_flash(CONFIG_JUNO_DTB_PART);
+
+	if (fdt_rom_addr == ~0UL)
+		return NULL;
+
+	return (void *)fdt_rom_addr;
+}
+#endif
+
 /*
  * Board specific reset that is system reset.
  */