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libfdt: Add new maximum phandle lookup function

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The fdt_get_max_phandle() function has some shortcomings. On one hand
it returns just a uint32_t which means to check for the "negative"
error code a caller has to explicitly check against the error code
(uint32_t)-1. In addition, the -1 is the only error code that can be
returned, so a caller cannot tell the difference between the various
failures.

Fix this by adding a new fdt_find_max_phandle() function that returns an
error code on failure and 0 on success, just like other APIs, and stores
the maximum phandle value in an output argument on success.

This also refactors fdt_get_max_phandle() to use the new function. Add a
note pointing out that the new fdt_find_max_phandle() function should be
preferred over fdt_get_max_phandle().

Signed-off-by: Thierry Reding <treding@nvidia.com>
Message-Id: <20190326153302.17109-1-thierry.reding@gmail.com>
[dwg: Reword for some inaccuracies in the commit message]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Thierry Reding
2019-03-26 16:33:00 +01:00
committed by David Gibson
parent 7fcf8208b8
commit 2bc5b66d7f
5 changed files with 56 additions and 15 deletions
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44
libfdt/fdt_ro.c
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@@ -144,32 +144,46 @@ static int fdt_string_eq_(const void *fdt, int stroffset,
return p && (slen == len) && (memcmp(p, s, len) == 0);
}
uint32_t fdt_get_max_phandle(const void *fdt)
int fdt_find_max_phandle(const void *fdt, uint32_t *phandle)
{
uint32_t max_phandle = 0;
int offset;
uint32_t max = 0;
int offset = -1;
for (offset = fdt_next_node(fdt, -1, NULL);;
offset = fdt_next_node(fdt, offset, NULL)) {
uint32_t phandle;
while (true) {
uint32_t value;
if (offset == -FDT_ERR_NOTFOUND)
return max_phandle;
offset = fdt_next_node(fdt, offset, NULL);
if (offset < 0) {
if (offset == -FDT_ERR_NOTFOUND)
break;
if (offset < 0)
return (uint32_t)-1;
return offset;
}
phandle = fdt_get_phandle(fdt, offset);
if (phandle == (uint32_t)-1)
continue;
value = fdt_get_phandle(fdt, offset);
if (phandle > max_phandle)
max_phandle = phandle;
if (value > max)
max = value;
}
if (phandle)
*phandle = max;
return 0;
}
uint32_t fdt_get_max_phandle(const void *fdt)
{
uint32_t phandle;
int err;
err = fdt_find_max_phandle(fdt, &phandle);
if (err < 0)
return (uint32_t)-1;
return phandle;
}
static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
{
int offset = n * sizeof(struct fdt_reserve_entry);