[PATCH] rockchip: spl: Cache boot source id for later use

[Jonas Karlman]

Rockchip BROM write a boot source id at CFG_IRAM_BASE + 0x10, the id
indicate from what storage media TPL/SPL was loaded from.

SPL use this value to determine what device "same-as-spl" represent when
determining from where FIT should be loaded. This works as long as the
boot_devices array contain a matching id <-> node path entry.

However, SPL typically load a small part of TF-A into SRAM and on RK3399
this overwrites the CFG_IRAM_BASE + 0x10 addr used for boot source id.

Here boot source id is 3 before FIT images is loaded, and 0 after:

  U-Boot SPL 2024.04-rc4 (Mar 15 2024 - 17:26:19 +0000)
  board_spl_was_booted_from: brom_bootdevice_id 3 maps to '/spi at ff1d0000/flash at 0'
  Trying to boot from SPI
  ## Checking hash(es) for config config-1 ... OK
  ## Checking hash(es) for Image atf-1 ... sha256+ OK
  ## Checking hash(es) for Image u-boot ... sha256+ OK
  ## Checking hash(es) for Image fdt-1 ... sha256+ OK
  ## Checking hash(es) for Image atf-2 ... sha256+ OK
  ## Checking hash(es) for Image atf-3 ... sha256+ OK
  board_spl_was_booted_from: failed to resolve brom_bootdevice_id 0
  spl_decode_boot_device: could not find udevice for /mmc at fe330000
  spl_decode_boot_device: could not find udevice for /mmc at fe320000
  spl_perform_fixups: could not map boot_device to ofpath: -19

Use a static bootdevice_brom_id to cache the boot source id after an
initial read from SRAM to fix this, this allow spl_perform_fixups() to
resolve correct boot source path for "same-as-spl" after SPL have loaded
TF-A related FIT images into memory.

With this the spl-boot-device prop can correctly be resolved to the
SPI flash node in the control FDT:

  => fdt addr ${fdtcontroladdr}
  Working FDT set to f1ee6710
  => fdt list /chosen
  chosen {
      u-boot,spl-boot-device = "/spi at ff1d0000/flash at 0";
      stdout-path = "serial2:1500000n8";
      u-boot,spl-boot-order = "same-as-spl", "/mmc at fe330000", "/mmc at fe320000";
  };

Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
---
 arch/arm/mach-rockchip/spl.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-rockchip/spl.c b/arch/arm/mach-rockchip/spl.c
index 1586a093fc37..27e996b504e7 100644
--- a/arch/arm/mach-rockchip/spl.c
+++ b/arch/arm/mach-rockchip/spl.c
@@ -32,9 +32,17 @@ __weak const char * const boot_devices[BROM_LAST_BOOTSOURCE + 1] = {
 
 const char *board_spl_was_booted_from(void)
 {
-	u32  bootdevice_brom_id = readl(BROM_BOOTSOURCE_ID_ADDR);
+	static u32 bootdevice_brom_id;
 	const char *bootdevice_ofpath = NULL;
 
+	if (!bootdevice_brom_id)
+		bootdevice_brom_id = readl(BROM_BOOTSOURCE_ID_ADDR);
+	if (!bootdevice_brom_id) {
+		debug("%s: unknown brom_bootdevice_id %x\n",
+		      __func__, bootdevice_brom_id);
+		return NULL;
+	}
+
 	if (bootdevice_brom_id < ARRAY_SIZE(boot_devices))
 		bootdevice_ofpath = boot_devices[bootdevice_brom_id];
 
-- 
2.43.2