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