cmd: blkls: Add blkls command

Add a command to print a list of available block device drivers,
and for each, the list of known block devices.

Signed-off-by: Niel Fourie <lusus@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>

test/py/tests/test_lsblk.py

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright (C) 2020
+# Niel Fourie, DENX Software Engineering, lusus@denx.de
+
+import pytest
+
+@pytest.mark.buildconfigspec('blk')
+@pytest.mark.buildconfigspec('cmd_lsblk')
+def test_lsblk(u_boot_console):
+    """Test that `lsblk` prints a result which includes `host`."""
+    output = u_boot_console.run_command('lsblk')
+    assert "Block Driver" in output
+    assert "sandbox_host_blk" in output