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rockchip: spl: support a 'same-as-spl'-specifier in the spl-boot-order

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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>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Philipp Tomsich 2017-09-29 19:27:57 +02:00
parent dbad01cab5
commit 80e9f88e67
2 changed files with 39 additions and 2 deletions
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29
arch/arm/mach-rockchip/spl-boot-order.c
View file

@ -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;

12
doc/device-tree-bindings/chosen.txt
View file

@ -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";
};
};