From a0dea6447c061896fdf468b5d492060e7108d5cb Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Wed, 20 Mar 2019 16:10:03 +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: <20190320151003.28941-1-thierry.reding@gmail.com> Signed-off-by: David Gibson --- cpukit/dtc/libfdt/fdt_ro.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'cpukit/dtc/libfdt/fdt_ro.c') diff --git a/cpukit/dtc/libfdt/fdt_ro.c b/cpukit/dtc/libfdt/fdt_ro.c index eafc142828..97cdcda0db 100644 --- a/cpukit/dtc/libfdt/fdt_ro.c +++ b/cpukit/dtc/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); -- cgit v1.2.3