diff options
| author | Thierry Reding <treding@nvidia.com> | 2019-03-26 16:33:02 +0100 |
|---|---|---|
| committer | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2020-03-02 07:52:19 +0100 |
| commit | 5a457750ec5b1916602da8f18565232916e9713e (patch) | |
| tree | fcf2e1d19c37d768841192600144b232f466ba12 /cpukit | |
| parent | 6505fe0edea8762955e3c8dc86801bb0679ba4f7 (diff) | |
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: <20190326153302.17109-3-thierry.reding@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Diffstat (limited to 'cpukit')
| -rw-r--r-- | cpukit/dtc/libfdt/fdt_ro.c | 18 | ||||
| -rw-r--r-- | cpukit/include/libfdt.h | 19 |
2 files changed, 37 insertions, 0 deletions
diff --git a/cpukit/dtc/libfdt/fdt_ro.c b/cpukit/dtc/libfdt/fdt_ro.c index 1d0335ee71..817ac39099 100644 --- a/cpukit/dtc/libfdt/fdt_ro.c +++ b/cpukit/dtc/libfdt/fdt_ro.c @@ -184,6 +184,24 @@ uint32_t fdt_get_max_phandle(const void *fdt) return phandle; } +int fdt_generate_phandle(const void *fdt, uint32_t *phandle) +{ + uint32_t max; + int err; + + err = fdt_find_max_phandle(fdt, &max); + if (err < 0) + return err; + + 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); diff --git a/cpukit/include/libfdt.h b/cpukit/include/libfdt.h index e1498c3c21..39ff6d5d25 100644 --- a/cpukit/include/libfdt.h +++ b/cpukit/include/libfdt.h @@ -140,6 +140,10 @@ #define FDT_ERR_MAX 17 +/* constants */ +#define FDT_MAX_PHANDLE 0xfffffffe + /* Valid values for phandles range from 1 to 2^32-2. */ + /**********************************************************************/ /* Low-level functions (you probably don't need these) */ /**********************************************************************/ @@ -417,6 +421,21 @@ int fdt_find_max_phandle(const void *fdt, uint32_t *phandle); uint32_t fdt_get_max_phandle(const void *fdt); /** + * fdt_generate_phandle - return a new, unused phandle for a device tree blob + * @fdt: pointer to the device tree blob + * @phandle: return location for the new phandle + * + * Walks the device tree blob and looks for the highest phandle value. On + * success, the new, unused phandle value (one higher than the previously + * highest phandle value in the device tree blob) will be returned in the + * @phandle parameter. + * + * Returns: + * 0 on success or a negative error-code on failure + */ +int fdt_generate_phandle(const void *fdt, uint32_t *phandle); + +/** * fdt_num_mem_rsv - retrieve the number of memory reserve map entries * @fdt: pointer to the device tree blob * |