1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* Counter - example userspace application |
3 | * |
4 | * The userspace application opens /dev/counter0, configures the |
5 | * COUNTER_EVENT_INDEX event channel 0 to gather Count 0 count and Count |
6 | * 1 count, and prints out the data as it becomes available on the |
7 | * character device node. |
8 | * |
9 | * Copyright (C) 2021 William Breathitt Gray |
10 | */ |
11 | #include <errno.h> |
12 | #include <fcntl.h> |
13 | #include <linux/counter.h> |
14 | #include <stdio.h> |
15 | #include <string.h> |
16 | #include <sys/ioctl.h> |
17 | #include <unistd.h> |
18 | |
19 | static struct counter_watch watches[2] = { |
20 | { |
21 | /* Component data: Count 0 count */ |
22 | .component.type = COUNTER_COMPONENT_COUNT, |
23 | .component.scope = COUNTER_SCOPE_COUNT, |
24 | .component.parent = 0, |
25 | /* Event type: Index */ |
26 | .event = COUNTER_EVENT_INDEX, |
27 | /* Device event channel 0 */ |
28 | .channel = 0, |
29 | }, |
30 | { |
31 | /* Component data: Count 1 count */ |
32 | .component.type = COUNTER_COMPONENT_COUNT, |
33 | .component.scope = COUNTER_SCOPE_COUNT, |
34 | .component.parent = 1, |
35 | /* Event type: Index */ |
36 | .event = COUNTER_EVENT_INDEX, |
37 | /* Device event channel 0 */ |
38 | .channel = 0, |
39 | }, |
40 | }; |
41 | |
42 | int main(void) |
43 | { |
44 | int fd; |
45 | int ret; |
46 | int i; |
47 | struct counter_event event_data[2]; |
48 | |
49 | fd = open("/dev/counter0" , O_RDWR); |
50 | if (fd == -1) { |
51 | perror("Unable to open /dev/counter0" ); |
52 | return 1; |
53 | } |
54 | |
55 | for (i = 0; i < 2; i++) { |
56 | ret = ioctl(fd, COUNTER_ADD_WATCH_IOCTL, watches + i); |
57 | if (ret == -1) { |
58 | fprintf(stderr, "Error adding watches[%d]: %s\n" , i, |
59 | strerror(errno)); |
60 | return 1; |
61 | } |
62 | } |
63 | ret = ioctl(fd, COUNTER_ENABLE_EVENTS_IOCTL); |
64 | if (ret == -1) { |
65 | perror("Error enabling events" ); |
66 | return 1; |
67 | } |
68 | |
69 | for (;;) { |
70 | ret = read(fd, event_data, sizeof(event_data)); |
71 | if (ret == -1) { |
72 | perror("Failed to read event data" ); |
73 | return 1; |
74 | } |
75 | |
76 | if (ret != sizeof(event_data)) { |
77 | fprintf(stderr, "Failed to read event data\n" ); |
78 | return -EIO; |
79 | } |
80 | |
81 | printf("Timestamp 0: %llu\tCount 0: %llu\n" |
82 | "Error Message 0: %s\n" |
83 | "Timestamp 1: %llu\tCount 1: %llu\n" |
84 | "Error Message 1: %s\n" , |
85 | event_data[0].timestamp, event_data[0].value, |
86 | strerror(event_data[0].status), |
87 | event_data[1].timestamp, event_data[1].value, |
88 | strerror(event_data[1].status)); |
89 | } |
90 | |
91 | return 0; |
92 | } |
93 | |