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.toms...@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";
};
};
--
2.1.4
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