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refactor(fdt): introduce common fdt_node_is_enabled()

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There are several users in the tree which want to check whether a given
FDT node is enabled or not: the "status" property holds that
information. So far all those users provide private implementations,
some of them having issues.

Export a generic implementation of that function in fdt_wrappers.h, as
a "static inline" function to not increase code size.
Also replace the existing implementation in Arm's fconf code, which had
a tiny bug in needlessly using the property length:
"status = [6f 6b 61 79 20];" would pass the check, where it should not.
The proper solution is also simpler: status must be a string, and
strings must be NUL-terminated in a DT. strcmp() would terminate on the
first NUL in *either* of the two strings it compares, so it would never
walk beyond the property boundary in the DTB.

Change-Id: I9d89093432f127c09add6cf5c93a725bc534e5de
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
This commit is contained in:
Andre Przywara 2023-02-03 11:11:18 +00:00
parent 1678bbb572
commit 49b268ce30
2 changed files with 10 additions and 15 deletions
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10
include/common/fdt_wrappers.h
View file

@ -10,6 +10,7 @@
#define FDT_WRAPPERS_H
#include <libfdt_env.h>
#include <libfdt.h>
/* Number of cells, given total length in bytes. Each cell is 4 bytes long */
#define NCELLS(len) ((len) / 4U)
@ -53,6 +54,15 @@ static inline uint32_t fdt_blob_size(const void *dtb)
return fdt32_to_cpu(dtb_header[1]);
}
static inline bool fdt_node_is_enabled(const void *fdt, int node)
{
int len;
const void *prop = fdt_getprop(fdt, node, "status", &len);
/* A non-existing status property means the device is enabled. */
return (prop == NULL) || (len == 5 && strcmp(prop, "okay") == 0);
}
#define fdt_for_each_compatible_node(dtb, node, compatible_str) \
for (node = fdt_node_offset_by_compatible(dtb, -1, compatible_str); \
node >= 0; \

15
plat/arm/common/fconf/fconf_ethosn_getter.c
View file

@ -20,21 +20,6 @@ struct ethosn_sub_allocator_t {
uint32_t stream_id;
};
static bool fdt_node_is_enabled(const void *fdt, int node)
{
int len;
const char *node_status;
node_status = fdt_getprop(fdt, node, "status", &len);
if (node_status == NULL ||
(len == 5 && /* Includes null character */
strncmp(node_status, "okay", 4U) == 0)) {
return true;
}
return false;
}
static bool fdt_node_has_reserved_memory(const void *fdt, int dev_node)
{
return fdt_get_property(fdt, dev_node, "memory-region", NULL) != NULL;