From 5a457750ec5b1916602da8f18565232916e9713e Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Tue, 26 Mar 2019 16:33:02 +0100 Subject: 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 Message-Id: <20190326153302.17109-3-thierry.reding@gmail.com> Signed-off-by: David Gibson --- cpukit/dtc/libfdt/fdt_ro.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'cpukit/dtc/libfdt') 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); -- cgit v1.2.3