tools/testing/selftests/timers/rtcpie.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/timers/rtcpie.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/timers/rtcpie.c
Extension
.c
Size
3178 bytes
Lines
142
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (fd == -1) {
			printf("Default RTC %s does not exist. Test Skipped!\n", default_rtc);
			exit(KSFT_SKIP);
		}
		close(fd);
		break;
	default:
		fprintf(stderr, "usage:  rtctest [rtcdev] [d]\n");
		return 1;
	}

	fd = open(rtc, O_RDONLY);

	if (fd ==  -1) {
		perror(rtc);
		exit(errno);
	}

	/* Read periodic IRQ rate */
	retval = ioctl(fd, RTC_IRQP_READ, &old_pie_rate);
	if (retval == -1) {
		/* not all RTCs support periodic IRQs */
		if (errno == EINVAL) {
			fprintf(stderr, "\nNo periodic IRQ support\n");
			goto done;
		}
		perror("RTC_IRQP_READ ioctl");
		exit(errno);
	}
	fprintf(stderr, "\nPeriodic IRQ rate is %ldHz.\n", old_pie_rate);

	fprintf(stderr, "Counting 20 interrupts at:");
	fflush(stderr);

	/* The frequencies 128Hz, 256Hz, ... 8192Hz are only allowed for root. */
	for (tmp=2; tmp<=64; tmp*=2) {

		retval = ioctl(fd, RTC_IRQP_SET, tmp);
		if (retval == -1) {
			/* not all RTCs can change their periodic IRQ rate */
			if (errno == EINVAL) {
				fprintf(stderr,
					"\n...Periodic IRQ rate is fixed\n");
				goto done;
			}
			perror("RTC_IRQP_SET ioctl");
			exit(errno);
		}

		fprintf(stderr, "\n%ldHz:\t", tmp);
		fflush(stderr);

		/* Enable periodic interrupts */
		retval = ioctl(fd, RTC_PIE_ON, 0);
		if (retval == -1) {
			perror("RTC_PIE_ON ioctl");
			exit(errno);
		}

		for (i=1; i<21; i++) {
			gettimeofday(&start, NULL);
			/* This blocks */
			retval = read(fd, &data, sizeof(unsigned long));
			if (retval == -1) {
				perror("read");
				exit(errno);
			}
			gettimeofday(&end, NULL);
			timersub(&end, &start, &diff);
			if (diff.tv_sec > 0 ||
			    diff.tv_usec > ((1000000L / tmp) * 1.10)) {
				fprintf(stderr, "\nPIE delta error: %ld.%06ld should be close to 0.%06ld\n",
				       diff.tv_sec, diff.tv_usec,
				       (1000000L / tmp));
				fflush(stdout);
				exit(-1);
			}

			fprintf(stderr, " %d",i);
			fflush(stderr);
		}

		/* Disable periodic interrupts */
		retval = ioctl(fd, RTC_PIE_OFF, 0);
		if (retval == -1) {
			perror("RTC_PIE_OFF ioctl");
			exit(errno);
		}
	}

Annotation

Implementation Notes