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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293// 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;}