linux/tools/counter/counter_example.c
William Breathitt Gray 086099893f tools/counter: Create Counter tools
This creates an example Counter program under tools/counter/*
to exemplify the Counter character device interface.

Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/7c0f975ba098952122302d258ec9ffdef04befaf.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2021-10-17 10:54:16 +01:00

93 lines
2.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/* Counter - example userspace application
*
* The userspace application opens /dev/counter0, configures the
* COUNTER_EVENT_INDEX event channel 0 to gather Count 0 count and Count
* 1 count, and prints out the data as it becomes available on the
* character device node.
*
* Copyright (C) 2021 William Breathitt Gray
*/
#include <errno.h>
#include <fcntl.h>
#include <linux/counter.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
static struct counter_watch watches[2] = {
{
/* Component data: Count 0 count */
.component.type = COUNTER_COMPONENT_COUNT,
.component.scope = COUNTER_SCOPE_COUNT,
.component.parent = 0,
/* Event type: Index */
.event = COUNTER_EVENT_INDEX,
/* Device event channel 0 */
.channel = 0,
},
{
/* Component data: Count 1 count */
.component.type = COUNTER_COMPONENT_COUNT,
.component.scope = COUNTER_SCOPE_COUNT,
.component.parent = 1,
/* Event type: Index */
.event = COUNTER_EVENT_INDEX,
/* Device event channel 0 */
.channel = 0,
},
};
int main(void)
{
int fd;
int ret;
int i;
struct counter_event event_data[2];
fd = open("/dev/counter0", O_RDWR);
if (fd == -1) {
perror("Unable to open /dev/counter0");
return 1;
}
for (i = 0; i < 2; i++) {
ret = ioctl(fd, COUNTER_ADD_WATCH_IOCTL, watches + i);
if (ret == -1) {
fprintf(stderr, "Error adding watches[%d]: %s\n", i,
strerror(errno));
return 1;
}
}
ret = ioctl(fd, COUNTER_ENABLE_EVENTS_IOCTL);
if (ret == -1) {
perror("Error enabling events");
return 1;
}
for (;;) {
ret = read(fd, event_data, sizeof(event_data));
if (ret == -1) {
perror("Failed to read event data");
return 1;
}
if (ret != sizeof(event_data)) {
fprintf(stderr, "Failed to read event data\n");
return -EIO;
}
printf("Timestamp 0: %llu\tCount 0: %llu\n"
"Error Message 0: %s\n"
"Timestamp 1: %llu\tCount 1: %llu\n"
"Error Message 1: %s\n",
event_data[0].timestamp, event_data[0].value,
strerror(event_data[0].status),
event_data[1].timestamp, event_data[1].value,
strerror(event_data[1].status));
}
return 0;
}