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器件型号：SK-AM62 工具/软件：
您好、
我们正在使用 am62x 和 Processor SDK 09.02.01.10开发器件。
是否有办法监测 eQEP 发出的事件(例如 COUNTER_EVENT_OVERFLOW、COUNTER_EVENT_UNDERFLOW)？
根据下一页、这可以通过使用 COUNTER_ADD_WATCH_IOCTL 来实现。
https://docs.kernel.org/driver-api/generic-counter.html#userspace
当我尝试在 linux-ti-staging 中使用 tools/counter/counter_example.c 获取溢出事件时、内核无法读取该事件并显示以下消息。
"无法处理虚拟地址0000000000000010处的内核 NULL 指针解除引用"
如果您有任何建议或想法、请告诉我。
附加了 counter_example.c 的源代码。
// 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>
#include <poll.h>
static struct counter_watch watches[1] = {
{
/* Component data: Count 0 count */
.component.type = COUNTER_COMPONENT_COUNT,
.component.scope = COUNTER_SCOPE_COUNT,
.component.parent = 0,
/* Event type: overflow */
.event = COUNTER_EVENT_OVERFLOW,
/* Device event channel 0 */
.channel = 0,
},
};
int main(void)
{
int fd;
int ret;
int i;
struct counter_event event_data[1];
fd = open("/dev/counter0", O_RDWR);
if (fd == -1) {
perror("Unable to open /dev/counter0");
return 1;
}
for (i = 0; i < 1; 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;
}
struct pollfd fds = {
.fd = fd,
.events = POLLIN,
};
for (;;) {
printf("polling\n");
int ret = poll(&fds, 1, -1);
if (ret >= 1) {
printf("read start\n");
ret = read(fd, event_data, sizeof(event_data));
printf("read end\n");
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",
event_data[0].timestamp, event_data[0].value,
strerror(event_data[0].status));
} else {
perror("poll()");
close(fd);
return -1;
}
}
return 0;
}
此致、
Takayuki
