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authorThierry Reding <treding@nvidia.com>2019-03-20 16:10:03 +0100
committerSebastian Huber <sebastian.huber@embedded-brains.de>2020-03-02 07:52:19 +0100
commita0dea6447c061896fdf468b5d492060e7108d5cb (patch)
treeb320618fe25321f227683283fe1e6880829874d5 /cpukit/include/libfdt.h
parentlibfdt: Fix FDT_ERR_NOTFOUND typos in documentation (diff)
downloadrtems-a0dea6447c061896fdf468b5d492060e7108d5cb.tar.bz2
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 'cpukit/include/libfdt.h')
-rw-r--r--cpukit/include/libfdt.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/cpukit/include/libfdt.h b/cpukit/include/libfdt.h
index a470d1df6d..7e102d188e 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) */
/**********************************************************************/
@@ -377,6 +381,21 @@ const char *fdt_string(const void *fdt, int stroffset);
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
*