[PATCH v2 2/3] rockchip: spl: Cache boot source id for later use

[Jonas Karlman]

Rockchip BROM writes a boot source id at CFG_IRAM_BASE + 0x10, this id
indicates from what storage media TPL/SPL was loaded from.

SPL uses this id 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.

For affected devices the u-boot,spl-boot-device would not be set when
booting from SPI flash and the flash at 0 node was not explicitly listed
in the u-boot,spl-boot-order prop.

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 brom_bootsource_id_cache to save 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";
  };

Fixes: d57e16c7e712 ("rockchip: find U-boot proper boot device by inverting the logic that sets it")
Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
Reviewed-by: Kever Yang <kever.yang at rock-chips.com>
---
v2:
- Only cache boot source id that can be resolved to a node path
- Make use of the new BROM_BOOTSOURCE_UNKNOWN enum value
- Update commit message
- Add fixes tag
- Collect r-b tag
---
 arch/arm/mach-rockchip/spl.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-rockchip/spl.c b/arch/arm/mach-rockchip/spl.c
index 1586a093fc37..3ce7e792b5a2 100644
--- a/arch/arm/mach-rockchip/spl.c
+++ b/arch/arm/mach-rockchip/spl.c
@@ -32,18 +32,26 @@ __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 brom_bootsource_id_cache = BROM_BOOTSOURCE_UNKNOWN;
+	u32 bootdevice_brom_id;
 	const char *bootdevice_ofpath = NULL;
 
+	if (brom_bootsource_id_cache != BROM_BOOTSOURCE_UNKNOWN)
+		bootdevice_brom_id = brom_bootsource_id_cache;
+	else
+		bootdevice_brom_id = readl(BROM_BOOTSOURCE_ID_ADDR);
+
 	if (bootdevice_brom_id < ARRAY_SIZE(boot_devices))
 		bootdevice_ofpath = boot_devices[bootdevice_brom_id];
 
-	if (bootdevice_ofpath)
+	if (bootdevice_ofpath) {
+		brom_bootsource_id_cache = bootdevice_brom_id;
 		debug("%s: brom_bootdevice_id %x maps to '%s'\n",
 		      __func__, bootdevice_brom_id, bootdevice_ofpath);
-	else
+	} else {
 		debug("%s: failed to resolve brom_bootdevice_id %x\n",
 		      __func__, bootdevice_brom_id);
+	}
 
 	return bootdevice_ofpath;
 }
-- 
2.43.2