selftest: rtc: Add to check rtc alarm status for alarm related test

In alarm_wkalm_set and alarm_wkalm_set_minute test, they use different
ioctl (RTC_ALM_SET/RTC_WKALM_SET) for alarm feature detection. They will
skip testing if RTC_ALM_SET/RTC_WKALM_SET ioctl returns an EINVAL error
code. This design may miss detecting real problems when the
efi.set_wakeup_time() return errors and then RTC_ALM_SET/RTC_WKALM_SET
ioctl returns an EINVAL error code with RTC_FEATURE_ALARM enabled.

In order to make rtctest more explicit and robust, we propose to use
RTC_PARAM_GET ioctl interface to check rtc alarm feature state before
running alarm related tests. If the kernel does not support RTC_PARAM_GET
ioctl interface, we will fallback to check the error number of
(RTC_ALM_SET/RTC_WKALM_SET) ioctl call for alarm feature detection.

Requires commit 101ca8d05913b ("rtc: efi: Enable SET/GET WAKEUP services
as optional")

Reviewed-by: Koba Ko <[e-mail]>
Reviewed-by: Matthew R. Ochs <[e-mail]>
Signed-off-by: Joseph Jang <[e-mail]>
Acked-by: Alexandre Belloni <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/rtc/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
-CFLAGS += -O3 -Wl,-no-as-needed -Wall
+CFLAGS += -O3 -Wl,-no-as-needed -Wall -I$(top_srcdir)/usr/include
 LDLIBS += -lrt -lpthread -lm
 
 TEST_GEN_PROGS = rtctest

tools/testing/selftests/rtc/rtctest.c

···
 
 static char *rtc_file = "/dev/rtc0";
 
+enum rtc_alarm_state {
+	RTC_ALARM_UNKNOWN,
+	RTC_ALARM_ENABLED,
+	RTC_ALARM_DISABLED,
+};
+
 FIXTURE(rtc) {
 	int fd;
 };
···
 		req.tv_sec = rem.tv_sec;
 		req.tv_nsec = rem.tv_nsec;
 	}
+}
+
+static enum rtc_alarm_state get_rtc_alarm_state(int fd)
+{
+	struct rtc_param param = { 0 };
+	int rc;
+
+	/* Validate kernel reflects unsupported RTC alarm state */
+	param.param = RTC_PARAM_FEATURES;
+	param.index = 0;
+	rc = ioctl(fd, RTC_PARAM_GET, &param);
+	if (rc < 0)
+		return RTC_ALARM_UNKNOWN;
+
+	if ((param.uvalue & _BITUL(RTC_FEATURE_ALARM)) == 0)
+		return RTC_ALARM_DISABLED;
+
+	return RTC_ALARM_ENABLED;
 }
 
 TEST_F_TIMEOUT(rtc, date_read_loop, READ_LOOP_DURATION_SEC + 2) {
···
 	fd_set readfds;
 	time_t secs, new;
 	int rc;
+	enum rtc_alarm_state alarm_state = RTC_ALARM_UNKNOWN;
 
 	if (self->fd == -1 && errno == ENOENT)
 		SKIP(return, "Skipping test since %s does not exist", rtc_file);
 	ASSERT_NE(-1, self->fd);
+
+	alarm_state = get_rtc_alarm_state(self->fd);
+	if (alarm_state == RTC_ALARM_DISABLED)
+		SKIP(return, "Skipping test since alarms are not supported.");
 
 	rc = ioctl(self->fd, RTC_RD_TIME, &tm);
 	ASSERT_NE(-1, rc);
···
 
 	rc = ioctl(self->fd, RTC_ALM_SET, &tm);
 	if (rc == -1) {
+		/*
+		 * Report error if rtc alarm was enabled. Fallback to check ioctl
+		 * error number if rtc alarm state is unknown.
+		 */
+		ASSERT_EQ(RTC_ALARM_UNKNOWN, alarm_state);
 		ASSERT_EQ(EINVAL, errno);
 		TH_LOG("skip alarms are not supported.");
 		return;
···
 	fd_set readfds;
 	time_t secs, new;
 	int rc;
+	enum rtc_alarm_state alarm_state = RTC_ALARM_UNKNOWN;
 
 	if (self->fd == -1 && errno == ENOENT)
 		SKIP(return, "Skipping test since %s does not exist", rtc_file);
 	ASSERT_NE(-1, self->fd);
+
+	alarm_state = get_rtc_alarm_state(self->fd);
+	if (alarm_state == RTC_ALARM_DISABLED)
+		SKIP(return, "Skipping test since alarms are not supported.");
 
 	rc = ioctl(self->fd, RTC_RD_TIME, &alarm.time);
 	ASSERT_NE(-1, rc);
···
 
 	rc = ioctl(self->fd, RTC_WKALM_SET, &alarm);
 	if (rc == -1) {
+		/*
+		 * Report error if rtc alarm was enabled. Fallback to check ioctl
+		 * error number if rtc alarm state is unknown.
+		 */
+		ASSERT_EQ(RTC_ALARM_UNKNOWN, alarm_state);
 		ASSERT_EQ(EINVAL, errno);
 		TH_LOG("skip alarms are not supported.");
 		return;
···
 	fd_set readfds;
 	time_t secs, new;
 	int rc;
+	enum rtc_alarm_state alarm_state = RTC_ALARM_UNKNOWN;
 
 	if (self->fd == -1 && errno == ENOENT)
 		SKIP(return, "Skipping test since %s does not exist", rtc_file);
 	ASSERT_NE(-1, self->fd);
+
+	alarm_state = get_rtc_alarm_state(self->fd);
+	if (alarm_state == RTC_ALARM_DISABLED)
+		SKIP(return, "Skipping test since alarms are not supported.");
 
 	rc = ioctl(self->fd, RTC_RD_TIME, &tm);
 	ASSERT_NE(-1, rc);
···
 
 	rc = ioctl(self->fd, RTC_ALM_SET, &tm);
 	if (rc == -1) {
+		/*
+		 * Report error if rtc alarm was enabled. Fallback to check ioctl
+		 * error number if rtc alarm state is unknown.
+		 */
+		ASSERT_EQ(RTC_ALARM_UNKNOWN, alarm_state);
 		ASSERT_EQ(EINVAL, errno);
 		TH_LOG("skip alarms are not supported.");
 		return;
···
 	fd_set readfds;
 	time_t secs, new;
 	int rc;
+	enum rtc_alarm_state alarm_state = RTC_ALARM_UNKNOWN;
 
 	if (self->fd == -1 && errno == ENOENT)
 		SKIP(return, "Skipping test since %s does not exist", rtc_file);
 	ASSERT_NE(-1, self->fd);
+
+	alarm_state = get_rtc_alarm_state(self->fd);
+	if (alarm_state == RTC_ALARM_DISABLED)
+		SKIP(return, "Skipping test since alarms are not supported.");
 
 	rc = ioctl(self->fd, RTC_RD_TIME, &alarm.time);
 	ASSERT_NE(-1, rc);
···
 
 	rc = ioctl(self->fd, RTC_WKALM_SET, &alarm);
 	if (rc == -1) {
+		/*
+		 * Report error if rtc alarm was enabled. Fallback to check ioctl
+		 * error number if rtc alarm state is unknown.
+		 */
+		ASSERT_EQ(RTC_ALARM_UNKNOWN, alarm_state);
 		ASSERT_EQ(EINVAL, errno);
 		TH_LOG("skip alarms are not supported.");
 		return;