test/py: test the ums command

This test invokes the "ums" command in U-Boot, and validates that a USB
storage device is enumerated on the test host system, and can be read
from.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>

test/py/tests/test_ums.py

@@ -0,0 +1,94 @@
+# Copyright (c) 2015-2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Test U-Boot's "ums" command. At present, this test only ensures that a UMS
+# device can be enumerated by the host/test machine. In the future, this test
+# should be enhanced to validate disk IO.
+
+import os
+import pytest
+import time
+
+'''
+Note: This test relies on:
+
+a) boardenv_* to contain configuration values to define which USB ports are
+available for testing. Without this, this test will be automatically skipped.
+For example:
+
+env__usb_dev_ports = (
+    {'tgt_usb_ctlr': '0', 'host_ums_dev_node': '/dev/disk/by-path/pci-0000:00:14.0-usb-0:13:1.0-scsi-0:0:0:0'},
+)
+
+env__block_devs = (
+    {'type': 'mmc', 'id': '0'}, # eMMC; always present
+    {'type': 'mmc', 'id': '1'}, # SD card; present since I plugged one in
+)
+
+b) udev rules to set permissions on devices nodes, so that sudo is not
+required. For example:
+
+ACTION=="add", SUBSYSTEM=="block", SUBSYSTEMS=="usb", KERNELS=="3-13", MODE:="666"
+
+(You may wish to change the group ID instead of setting the permissions wide
+open. All that matters is that the user ID running the test can access the
+device.)
+'''
+
+def open_ums_device(host_ums_dev_node):
+    '''Attempt to open a device node, returning either the opened file handle,
+    or None on any error.'''
+
+    try:
+        return open(host_ums_dev_node, 'rb')
+    except:
+        return None
+
+def wait_for_ums_device(host_ums_dev_node):
+    '''Continually attempt to open the device node exported by the "ums"
+    command, and either return the opened file handle, or raise an exception
+    after a timeout.'''
+
+    for i in xrange(100):
+        fh = open_ums_device(host_ums_dev_node)
+        if fh:
+            return fh
+        time.sleep(0.1)
+    raise Exception('UMS device did not appear')
+
+def wait_for_ums_device_gone(host_ums_dev_node):
+    '''Continually attempt to open the device node exported by the "ums"
+    command, and either return once the device has disappeared, or raise an
+    exception if it does not before a timeout occurs.'''
+
+    for i in xrange(100):
+        fh = open_ums_device(host_ums_dev_node)
+        if not fh:
+            return
+        fh.close()
+        time.sleep(0.1)
+    raise Exception('UMS device did not disappear')
+
+@pytest.mark.buildconfigspec('cmd_usb_mass_storage')
+def test_ums(u_boot_console, env__usb_dev_port, env__block_devs):
+    '''Test the "ums" command; the host system must be able to enumerate a UMS
+    device when "ums" is running, and this device must disappear when "ums" is
+    aborted.'''
+
+    tgt_usb_ctlr = env__usb_dev_port['tgt_usb_ctlr']
+    host_ums_dev_node = env__usb_dev_port['host_ums_dev_node']
+
+    # We're interested in testing USB device mode on each port, not the cross-
+    # product of that with each device. So, just pick the first entry in the
+    # device list here. We'll test each block device somewhere else.
+    tgt_dev_type = env__block_devs[0]['type']
+    tgt_dev_id = env__block_devs[0]['id']
+
+    cmd = 'ums %s %s %s' % (tgt_usb_ctlr, tgt_dev_type, tgt_dev_id)
+    u_boot_console.run_command('ums 0 mmc 0', wait_for_prompt=False)
+    fh = wait_for_ums_device(host_ums_dev_node)
+    fh.read(4096)
+    fh.close()
+    u_boot_console.ctrlc()
+    wait_for_ums_device_gone(host_ums_dev_node)