160 lines
3.6 KiB
C
160 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* udelay() test kernel module
|
|
*
|
|
* Test is executed by writing and reading to /sys/kernel/debug/udelay_test
|
|
* Tests are configured by writing: USECS ITERATIONS
|
|
* Tests are executed by reading from the same file.
|
|
* Specifying usecs of 0 or negative values will run multiples tests.
|
|
*
|
|
* Copyright (C) 2014 Google, Inc.
|
|
*/
|
|
|
|
#include <linux/debugfs.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/ktime.h>
|
|
#include <linux/module.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
#define DEFAULT_ITERATIONS 100
|
|
|
|
#define DEBUGFS_FILENAME "udelay_test"
|
|
|
|
static DEFINE_MUTEX(udelay_test_lock);
|
|
static int udelay_test_usecs;
|
|
static int udelay_test_iterations = DEFAULT_ITERATIONS;
|
|
|
|
static int udelay_test_single(struct seq_file *s, int usecs, uint32_t iters)
|
|
{
|
|
int min = 0, max = 0, fail_count = 0;
|
|
uint64_t sum = 0;
|
|
uint64_t avg;
|
|
int i;
|
|
/* Allow udelay to be up to 0.5% fast */
|
|
int allowed_error_ns = usecs * 5;
|
|
|
|
for (i = 0; i < iters; ++i) {
|
|
s64 kt1, kt2;
|
|
int time_passed;
|
|
|
|
kt1 = ktime_get_ns();
|
|
udelay(usecs);
|
|
kt2 = ktime_get_ns();
|
|
time_passed = kt2 - kt1;
|
|
|
|
if (i == 0 || time_passed < min)
|
|
min = time_passed;
|
|
if (i == 0 || time_passed > max)
|
|
max = time_passed;
|
|
if ((time_passed + allowed_error_ns) / 1000 < usecs)
|
|
++fail_count;
|
|
WARN_ON(time_passed < 0);
|
|
sum += time_passed;
|
|
}
|
|
|
|
avg = sum;
|
|
do_div(avg, iters);
|
|
seq_printf(s, "%d usecs x %d: exp=%d allowed=%d min=%d avg=%lld max=%d",
|
|
usecs, iters, usecs * 1000,
|
|
(usecs * 1000) - allowed_error_ns, min, avg, max);
|
|
if (fail_count)
|
|
seq_printf(s, " FAIL=%d", fail_count);
|
|
seq_puts(s, "\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int udelay_test_show(struct seq_file *s, void *v)
|
|
{
|
|
int usecs;
|
|
int iters;
|
|
int ret = 0;
|
|
|
|
mutex_lock(&udelay_test_lock);
|
|
usecs = udelay_test_usecs;
|
|
iters = udelay_test_iterations;
|
|
mutex_unlock(&udelay_test_lock);
|
|
|
|
if (usecs > 0 && iters > 0) {
|
|
return udelay_test_single(s, usecs, iters);
|
|
} else if (usecs == 0) {
|
|
struct timespec64 ts;
|
|
|
|
ktime_get_ts64(&ts);
|
|
seq_printf(s, "udelay() test (lpj=%ld kt=%lld.%09ld)\n",
|
|
loops_per_jiffy, (s64)ts.tv_sec, ts.tv_nsec);
|
|
seq_puts(s, "usage:\n");
|
|
seq_puts(s, "echo USECS [ITERS] > " DEBUGFS_FILENAME "\n");
|
|
seq_puts(s, "cat " DEBUGFS_FILENAME "\n");
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int udelay_test_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, udelay_test_show, inode->i_private);
|
|
}
|
|
|
|
static ssize_t udelay_test_write(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *pos)
|
|
{
|
|
char lbuf[32];
|
|
int ret;
|
|
int usecs;
|
|
int iters;
|
|
|
|
if (count >= sizeof(lbuf))
|
|
return -EINVAL;
|
|
|
|
if (copy_from_user(lbuf, buf, count))
|
|
return -EFAULT;
|
|
lbuf[count] = '\0';
|
|
|
|
ret = sscanf(lbuf, "%d %d", &usecs, &iters);
|
|
if (ret < 1)
|
|
return -EINVAL;
|
|
else if (ret < 2)
|
|
iters = DEFAULT_ITERATIONS;
|
|
|
|
mutex_lock(&udelay_test_lock);
|
|
udelay_test_usecs = usecs;
|
|
udelay_test_iterations = iters;
|
|
mutex_unlock(&udelay_test_lock);
|
|
|
|
return count;
|
|
}
|
|
|
|
static const struct file_operations udelay_test_debugfs_ops = {
|
|
.owner = THIS_MODULE,
|
|
.open = udelay_test_open,
|
|
.read = seq_read,
|
|
.write = udelay_test_write,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
static int __init udelay_test_init(void)
|
|
{
|
|
mutex_lock(&udelay_test_lock);
|
|
debugfs_create_file(DEBUGFS_FILENAME, S_IRUSR, NULL, NULL,
|
|
&udelay_test_debugfs_ops);
|
|
mutex_unlock(&udelay_test_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
module_init(udelay_test_init);
|
|
|
|
static void __exit udelay_test_exit(void)
|
|
{
|
|
mutex_lock(&udelay_test_lock);
|
|
debugfs_lookup_and_remove(DEBUGFS_FILENAME, NULL);
|
|
mutex_unlock(&udelay_test_lock);
|
|
}
|
|
|
|
module_exit(udelay_test_exit);
|
|
|
|
MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
|
|
MODULE_LICENSE("GPL");
|