dm: eth: Add support for aliases

Allow network devices to be referred to as "eth0" instead of
"eth@12345678" when specified in ethact.

Add tests to verify this behavior.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/eth.c b/test/dm/eth.c
index 04ccf49..5688b71 100644
--- a/test/dm/eth.c
+++ b/test/dm/eth.c
@@ -36,3 +36,27 @@
 	return 0;
 }
 DM_TEST(dm_test_eth, DM_TESTF_SCAN_FDT);
+
+static int dm_test_eth_alias(struct dm_test_state *dms)
+{
+	NetPingIP = string_to_ip("1.1.2.2");
+	setenv("ethact", "eth0");
+	ut_assertok(NetLoop(PING));
+	ut_asserteq_str("eth@10002000", getenv("ethact"));
+
+	setenv("ethact", "eth1");
+	ut_assertok(NetLoop(PING));
+	ut_asserteq_str("eth@10004000", getenv("ethact"));
+
+	/* Expected to fail since eth2 is not defined in the device tree */
+	setenv("ethact", "eth2");
+	ut_assertok(NetLoop(PING));
+	ut_asserteq_str("eth@10002000", getenv("ethact"));
+
+	setenv("ethact", "eth5");
+	ut_assertok(NetLoop(PING));
+	ut_asserteq_str("eth@10003000", getenv("ethact"));
+
+	return 0;
+}
+DM_TEST(dm_test_eth_alias, DM_TESTF_SCAN_FDT);
diff --git a/test/dm/test.dts b/test/dm/test.dts
index 762ddc3..0ab0916 100644
--- a/test/dm/test.dts
+++ b/test/dm/test.dts
@@ -18,6 +18,8 @@
 		testfdt3 = "/b-test";
 		testfdt5 = "/some-bus/c-test@5";
 		testfdt8 = "/a-test";
+		eth0 = "/eth@10002000";
+		eth5 = &eth_5;
 	};
 
 	uart0: serial {
@@ -172,7 +174,7 @@
 		fake-host-hwaddr = <0x00 0x00 0x66 0x44 0x22 0x00>;
 	};
 
-	eth@10003000 {
+	eth_5: eth@10003000 {
 		compatible = "sandbox,eth";
 		reg = <0x10003000 0x1000>;
 		fake-host-hwaddr = <0x00 0x00 0x66 0x44 0x22 0x11>;