diff options
author | Thierry Reding <treding@nvidia.com> | 2019-03-20 16:10:03 +0100 |
---|---|---|
committer | David Gibson <david@gibson.dropbear.id.au> | 2019-03-21 11:37:44 +1100 |
commit | 54ea41c22415cb0e283d22faf71202051c89400c (patch) | |
tree | 0e4e04e459ac6d131a38ccf864eb82f6e55fe176 /libfdt/fdt_ro.c | |
parent | 4762ad051ee0a654a17c67eb6d8e33196b475b81 (diff) | |
download | device-tree-compiler-54ea41c22415cb0e283d22faf71202051c89400c.tar.gz |
libfdt: Add phandle generation helper
The new fdt_generate_phandle() function can be used to generate a new,
unused phandle given a specific device tree blob. The implementation is
somewhat naive in that it simply walks the entire device tree to find
the highest phandle value and then returns a phandle value one higher
than that. A more clever implementation might try to find holes in the
current set of phandle values and fill them. But this implementation is
relatively simple and works reliably.
Also add a test that validates that phandles generated by this new API
are indeed unique.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Message-Id: <20190320151003.28941-1-thierry.reding@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Diffstat (limited to 'libfdt/fdt_ro.c')
-rw-r--r-- | libfdt/fdt_ro.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c index eafc142..97cdcda 100644 --- a/libfdt/fdt_ro.c +++ b/libfdt/fdt_ro.c @@ -170,6 +170,37 @@ uint32_t fdt_get_max_phandle(const void *fdt) return 0; } +int fdt_generate_phandle(const void *fdt, uint32_t *phandle) +{ + uint32_t max = 0; + int offset = -1; + + while (true) { + uint32_t value; + + offset = fdt_next_node(fdt, offset, NULL); + if (offset < 0) { + if (offset == -FDT_ERR_NOTFOUND) + break; + + return offset; + } + + value = fdt_get_phandle(fdt, offset); + + if (value > max) + max = value; + } + + if (max == FDT_MAX_PHANDLE) + return -FDT_ERR_NOPHANDLES; + + if (phandle) + *phandle = max + 1; + + return 0; +} + static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n) { int offset = n * sizeof(struct fdt_reserve_entry); |