test/py: add MMC/SD block write test

Add a standalone MMC block write test. This allows direct testing of MMC
access rather than relying on doing so as a side-effect of e.g. DFU or
UMS testing, which may not be enabled on all platforms.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
diff --git a/test/py/tests/test_mmc_wr.py b/test/py/tests/test_mmc_wr.py
new file mode 100644
index 0000000..601279a
--- /dev/null
+++ b/test/py/tests/test_mmc_wr.py
@@ -0,0 +1,105 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2019, Texas Instrument
+# Author: Jean-Jacques Hiblot <jjhiblot@ti.com>
+
+# Test U-Boot's "mmc write" command. The test generates random data, writes it
+# to the eMMC or SD card, then reads it back and performs a comparison.
+
+import pytest
+import u_boot_utils
+
+"""
+This test relies on boardenv_* to containing configuration values to define
+which MMC devices should be tested. For example:
+
+env__mmc_wr_configs = (
+    {
+        "fixture_id": "emmc-boot0",
+        "is_emmc": True,
+        "devid": 1,
+        "partid": 1,
+        "sector": 0x10,
+        "count": 100,
+        "test_iterations": 50,
+    },
+    {
+        "fixture_id": "emmc-boot1",
+        "is_emmc": True,
+        "devid": 1,
+        "partid": 2,
+        "sector": 0x10,
+        "count": 100,
+        "test_iterations": 50,
+    },
+)
+
+"""
+
+@pytest.mark.buildconfigspec('cmd_mmc','cmd_memory')
+def test_mmc_wr(u_boot_console, env__mmc_wr_config):
+    """Test the "mmc write" command.
+
+    Args:
+        u_boot_console: A U-Boot console connection.
+        env__mmc_wr_config: The single MMC configuration on which
+            to run the test. See the file-level comment above for details
+            of the format.
+
+    Returns:
+        Nothing.
+    """
+
+    is_emmc = env__mmc_wr_config['is_emmc']
+    devid = env__mmc_wr_config['devid']
+    partid = env__mmc_wr_config.get('partid', 0)
+    sector = env__mmc_wr_config.get('sector', 0)
+    count_sectors = env__mmc_wr_config.get('count', 1)
+    test_iterations = env__mmc_wr_config.get('test_iterations', 1)
+
+
+    count_bytes = count_sectors * 512
+    bcfg = u_boot_console.config.buildconfig
+    ram_base = u_boot_utils.find_ram_base(u_boot_console)
+    src_addr = '0x%08x' % ram_base
+    dst_addr = '0x%08x' % (ram_base + count_bytes)
+
+
+    for i in range(test_iterations):
+	# Generate random data
+	cmd = 'random %s %x' % (src_addr, count_bytes)
+	response = u_boot_console.run_command(cmd)
+	good_response = '%d bytes filled with random data' % (count_bytes)
+	assert good_response in response
+
+	# Select MMC device
+	cmd = 'mmc dev %d' % devid
+	if is_emmc:
+		cmd += ' %d' % partid
+	response = u_boot_console.run_command(cmd)
+	assert 'no card present' not in response
+	if is_emmc:
+		partid_response = "(part %d)" % partid
+	else:
+		partid_response = ""
+	good_response = 'mmc%d%s is current device' % (devid, partid_response)
+	assert good_response in response
+
+	# Write data
+	cmd = 'mmc write %s %x %x' % (src_addr, sector, count_sectors)
+	response = u_boot_console.run_command(cmd)
+	good_response = 'MMC write: dev # %d, block # %d, count %d ... %d blocks written: OK' % (
+		devid, sector, count_sectors, count_sectors)
+	assert good_response in response
+
+	# Read data
+	cmd = 'mmc read %s %x %x' % (dst_addr, sector, count_sectors)
+	response = u_boot_console.run_command(cmd)
+	good_response = 'MMC read: dev # %d, block # %d, count %d ... %d blocks read: OK' % (
+		devid, sector, count_sectors, count_sectors)
+	assert good_response in response
+
+	# Compare src and dst data
+	cmd = 'cmp.b %s %s %x' % (src_addr, dst_addr, count_bytes)
+	response = u_boot_console.run_command(cmd)
+	good_response = 'Total of %d byte(s) were the same' % (count_bytes)
+	assert good_response in response