FDT: implement fdt_ether_get_addr()

Introduce fdt_ether_get_addr() in fdt_common.c/h that tries standard
DT properties in the correct order and falls back to a random address
when needed. This should be used by ethernet drivers instead of open-coding
the same logic.

MFC after:	2 weeks

Reviewed by:	mhorne, adrian, bz, jrtc27
Differential Revision:	https://reviews.freebsd.org/D58104

2 files changed, 44 insertions, 0 deletions

diff --git a/sys/dev/fdt/fdt_common.c b/sys/dev/fdt/fdt_common.c
index f43551c6310e..93897b598b30 100644
--- a/sys/dev/fdt/fdt_common.c
+++ b/sys/dev/fdt/fdt_common.c
@@ -553,3 +553,43 @@ fdt_get_chosen_bootargs(char *bootargs, size_t max_size)
 		return (ENXIO);
 	return (0);
 }
+
+/*
+ * fdt_ether_get_addr - Get ethernet MAC address using FDT properties.
+ * Order:
+ *   1. "mac-address"
+ *   2. "local-mac-address"
+ *   3. Keep pre-initialized value (if valid)
+ *   4. random ether_gen_addr() as last resort
+ */
+void
+fdt_ether_get_addr(phandle_t node, struct ifnet *ifp, uint8_t *eaddr)
+{
+	uint8_t tmp[ETHER_ADDR_LEN];
+	int len;
+
+	/* Firstly try "mac-address" */
+	len = OF_getprop(node, "mac-address", tmp, sizeof(tmp));
+	if (len == ETHER_ADDR_LEN && !ETHER_IS_ZERO(tmp) &&
+	    !ETHER_IS_MULTICAST(tmp)) {
+		bcopy(tmp, eaddr, ETHER_ADDR_LEN);
+		return;
+	}
+
+	/* Next use  "local-mac-address" */
+	len = OF_getprop(node, "local-mac-address", tmp, sizeof(tmp));
+	if (len == ETHER_ADDR_LEN && !ETHER_IS_ZERO(tmp) &&
+	    !ETHER_IS_MULTICAST(tmp)) {
+		bcopy(tmp, eaddr, ETHER_ADDR_LEN);
+		return;
+	}
+
+	/* Next use existing one if set */
+	if (!ETHER_IS_ZERO(eaddr) && !ETHER_IS_MULTICAST(eaddr))
+		return;
+
+	/* Last resort - generate random one */
+	ether_gen_addr(ifp, (struct ether_addr *)eaddr);
+
+	return;
+}
diff --git a/sys/dev/fdt/fdt_common.h b/sys/dev/fdt/fdt_common.h
index f597233f9771..3eee6913ad72 100644
--- a/sys/dev/fdt/fdt_common.h
+++ b/sys/dev/fdt/fdt_common.h
@@ -33,8 +33,11 @@
 
 #include <sys/sysctl.h>
 #include <sys/slicer.h>
+#include <sys/socket.h>
 #include <contrib/libfdt/libfdt_env.h>
 #include <dev/ofw/ofw_bus.h>
+#include <net/ethernet.h>
+#include <net/if.h>
 
 #define FDT_MEM_REGIONS	64
 
@@ -70,6 +73,7 @@ typedef void (*fdt_mem_region_cb)(const struct mem_region *, void *);
 int fdt_addrsize_cells(phandle_t, int *, int *);
 u_long fdt_data_get(const void *, int);
 int fdt_data_to_res(const pcell_t *, int, int, u_long *, u_long *);
+void fdt_ether_get_addr(phandle_t node, struct ifnet *ifp, uint8_t *eaddr);
 phandle_t fdt_find_compatible(phandle_t, const char *, int);
 phandle_t fdt_depth_search_compatible(phandle_t, const char *, int);
 int fdt_foreach_mem_region(fdt_mem_region_cb, void *);