fdt: prevent clearing memory node if there are no banks

Avoid clearing the reg property in the memory DT node if no memory
banks have been specified for a board (CONFIG_NR_DRAM_BANKS == 0).
This allows boards to let U-Boot skip the DT memory tinkering in case
other firmware has already setup the node properly before.
This should be safe as all callers of fdt_fixup_memory_banks that use
a computed <banks> value put at least 1 in there.
Add some documentation comments to the header file.

Signed-off-by: Andre Przywara <osp@andrep.de>
Acked-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Andre Przywara 2015-06-21 00:29:54 +01:00 committed by Simon Glass
parent 605e15db2b
commit 5c1cf89f8c
2 changed files with 29 additions and 0 deletions

View File

@ -454,6 +454,9 @@ int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[], int banks)
return err;
}
if (!banks)
return 0;
len = fdt_pack_reg(blob, tmp, start, size, banks);
err = fdt_setprop(blob, nodeoffset, "reg", tmp, len);

View File

@ -67,8 +67,34 @@ void do_fixup_by_compat(void *fdt, const char *compat,
const char *prop, const void *val, int len, int create);
void do_fixup_by_compat_u32(void *fdt, const char *compat,
const char *prop, u32 val, int create);
/**
* Setup the memory node in the DT. Creates one if none was existing before.
* Calls fdt_fixup_memory_banks() to populate a single reg pair covering the
* whole memory.
*
* @param blob FDT blob to update
* @param start Begin of DRAM mapping in physical memory
* @param size Size of the single memory bank
* @return 0 if ok, or -1 or -FDT_ERR_... on error
*/
int fdt_fixup_memory(void *blob, u64 start, u64 size);
/**
* Fill the DT memory node with multiple memory banks.
* Creates the node if none was existing before.
* If banks is 0, it will not touch the existing reg property. This allows
* boards to not mess with the existing DT setup, which may have been
* filled in properly before.
*
* @param blob FDT blob to update
* @param start Array of size <banks> to hold the start addresses.
* @param size Array of size <banks> to hold the size of each region.
* @param banks Number of memory banks to create. If 0, the reg
* property will be left untouched.
* @return 0 if ok, or -1 or -FDT_ERR_... on error
*/
int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[], int banks);
void fdt_fixup_ethernet(void *fdt);
int fdt_find_and_setprop(void *fdt, const char *node, const char *prop,
const void *val, int len, int create);