tools: add script to test udelay

#!/bin/bash

# udelay() test script

#

# Test is executed by writing and reading to /sys/kernel/debug/udelay_test

# and exercises a variety of delays to ensure that udelay() is delaying

# at least as long as requested (as compared to ktime).

#

# Copyright (C) 2014 Google, Inc.

#

# This software is licensed under the terms of the GNU General Public

# License version 2, as published by the Free Software Foundation, and

# may be copied, distributed, and modified under those terms.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

MODULE_NAME=udelay_test

UDELAY_PATH=/sys/kernel/debug/udelay_test

setup()

{

	/sbin/modprobe -q $MODULE_NAME

	tmp_file=`mktemp`

}

test_one()

{

	delay=$1

	echo $delay > $UDELAY_PATH

	tee -a $tmp_file < $UDELAY_PATH

}

cleanup()

{

	if [ -f $tmp_file ]; then

		rm $tmp_file

	fi

	/sbin/modprobe -q -r $MODULE_NAME

}

trap cleanup EXIT

setup

# Delay for a variety of times.

# 1..200, 200..500 (by 10), 500..2000 (by 100)

for (( delay = 1; delay < 200; delay += 1 )); do

	test_one $delay

done

for (( delay = 200; delay < 500; delay += 10 )); do

	test_one $delay

done

for (( delay = 500; delay <= 2000; delay += 100 )); do

	test_one $delay

done

# Search for failures

count=`grep -c FAIL $tmp_file`

if [ $? -eq "0" ]; then

	echo "ERROR: $count delays failed to delay long enough"

	retcode=1

fi

exit $retcode