It is often desirable to configure the spl-boot-order (i.e. the order that SPL probes devices to find the FIT image containing a full U-Boot) such that it contains 'the same device the SPL stage was booted from' early on. To support this, we introduce the 'same-as-spl' specifier for the spl-boot-order property.
This commit adds: - documentation for the new board_spl_was_booted_from() function that individual SoCs/boards should provide, if they can determine where the SPL was booted from - implements the new board_spl_was_booted_from() stub function - adds support for handling the 'same-as-spl' specifier and calling into the per-SoC/per-board support code.
This also updates the documentation for the 'u-boot,spl-boot-order' property.
Signed-off-by: Philipp Tomsich philipp.tomsich@theobroma-systems.com ---
arch/arm/mach-rockchip/spl-boot-order.c | 29 ++++++++++++++++++++++++++++- doc/device-tree-bindings/chosen.txt | 12 +++++++++++- 2 files changed, 39 insertions(+), 2 deletions(-)
diff --git a/arch/arm/mach-rockchip/spl-boot-order.c b/arch/arm/mach-rockchip/spl-boot-order.c index 0bb9a73..843998d 100644 --- a/arch/arm/mach-rockchip/spl-boot-order.c +++ b/arch/arm/mach-rockchip/spl-boot-order.c @@ -76,6 +76,24 @@ static int spl_node_to_boot_device(int node) return -1; }
+/** + * board_spl_was_booted_from() - retrieves the of-path the SPL was loaded from + * + * To support a 'same-as-spl' specification in the search-order for the next + * stage, we need a SoC- or board-specific way to handshake with what 'came + * before us' (either a BROM or TPL stage) and map the info retrieved onto + * a OF path. + * + * Returns + * NULL, on failure or if the device could not be identified + * a of_path (a string), on success + */ +__weak const char *board_spl_was_booted_from(void) +{ + debug("%s: no support for 'same-as-spl' for this board\n", __func__); + return NULL; +} + void board_boot_order(u32 *spl_boot_list) { const void *blob = gd->fdt_blob; @@ -97,8 +115,17 @@ void board_boot_order(u32 *spl_boot_list) (conf = fdt_stringlist_get(blob, chosen_node, "u-boot,spl-boot-order", elem, NULL)); elem++) { + const char *alias; + + /* Handle the case of 'same device the SPL was loaded from' */ + if (strncmp(conf, "same-as-spl", 11) == 0) { + conf = board_spl_was_booted_from(); + if (!conf) + continue; + } + /* First check if the list element is an alias */ - const char *alias = fdt_get_alias(blob, conf); + alias = fdt_get_alias(blob, conf); if (alias) conf = alias;
diff --git a/doc/device-tree-bindings/chosen.txt b/doc/device-tree-bindings/chosen.txt index 5625d21..c96b8f7 100644 --- a/doc/device-tree-bindings/chosen.txt +++ b/doc/device-tree-bindings/chosen.txt @@ -56,10 +56,20 @@ Each list element of the property should specify a device to be probed in the order they are listed: references (i.e. implicit paths), a full path or an alias is expected for each entry.
+A special specifier "same-as-spl" can be used at any position in the +boot-order to direct U-Boot to insert the device the SPL was booted +from there. Whether this is indeed inserted or silently ignored (if +it is not supported on any given SoC/board or if the boot-device is +not available to continue booting from) is implementation-defined. +Note that if "same-as-spl" expands to an actual node for a given +board, the corresponding node may appear multiple times in the +boot-order (as there currently exists no mechanism to suppress +duplicates from the list). + Example ------- / { chosen { - u-boot,spl-boot-order = &sdmmc, "/sdhci@fe330000"; + u-boot,spl-boot-order = "same-as-spl", &sdmmc, "/sdhci@fe330000"; }; };