fdt: Add a function to return PCI BDF triplet

The fdtdec_pci_get_bdf() function returns the bus, device, function
triplet of a PCI device by parsing the "reg" property according to the
PCI device tree binding.

Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

include/fdtdec.h

@@ -649,4 +649,15 @@ int fdt_get_named_resource(const void *fdt, int node, const char *property,
 			   const char *prop_names, const char *name,
 			   struct fdt_resource *res);
 
+/**
+ * Look at the reg property of a device node that represents a PCI device
+ * and parse the bus, device and function number from it.
+ *
+ * @param fdt		FDT blob
+ * @param node		node to examine
+ * @param bdf		returns bus, device, function triplet
+ * @return 0 if ok, negative on error
+ */
+int fdtdec_pci_get_bdf(const void *fdt, int node, int *bdf);
+
 #endif

lib/fdtdec.c

@@ -765,4 +765,18 @@ int fdt_get_named_resource(const void *fdt, int node, const char *property,
 
 	return fdt_get_resource(fdt, node, property, index, res);
 }
+
+int fdtdec_pci_get_bdf(const void *fdt, int node, int *bdf)
+{
+	const fdt32_t *prop;
+	int len;
+
+	prop = fdt_getprop(fdt, node, "reg", &len);
+	if (!prop)
+		return len;
+
+	*bdf = fdt32_to_cpu(*prop) & 0xffffff;
+
+	return 0;
+}
 #endif