[LTP] [PATCH 1/3] lib: add tst_rtctime* for rtc test

[gengcixi@gmail.com <gengcixi@gmail.com>]

From: Cixi Geng <cixi.geng1@unisoc.com>

Add:
    get rtc time and set rtc time in default /dev/rtc;
    Implemented a function that covert rtc time to time_t
    this will be used in tst_rtc_save and tst_rtc_restore

Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
---
 include/tst_rtctime.h |  15 ++++
 lib/tst_rtctime.c     | 161 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 176 insertions(+)
 create mode 100644 include/tst_rtctime.h
 create mode 100644 lib/tst_rtctime.c

diff --git a/include/tst_rtctime.h b/include/tst_rtctime.h
new file mode 100644
index 000000000..61ec6f0eb
--- /dev/null
+++ b/include/tst_rtctime.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Unisoc Inc.
+ */
+
+#ifndef TST_RTCTIME
+#define TST_RTCTIME
+
+#include <linux/rtc.h>
+
+int tst_rtc_gettime(struct rtc_time *rtc_tm);
+
+int tst_rtc_settime(struct rtc_time *rtc_tm);
+
+#endif /* TST_RTCTIME */
diff --git a/lib/tst_rtctime.c b/lib/tst_rtctime.c
new file mode 100644
index 000000000..580ef0fdf
--- /dev/null
+++ b/lib/tst_rtctime.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Unisoc Communications Inc.
+ *
+ * Filename : tst_rtctime.c
+ * Abstract : This file is a implementation for rtc set read,covert to tm functions
+ */
+
+#include <linux/rtc.h>
+#include <stdbool.h>
+#include <limits.h>
+#define TST_NO_DEFAULT_MAIN
+#include "tst_test.h"
+#include "tst_rtctime.h"
+
+#define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
+
+static const unsigned char rtc_days_in_month[] = {
+	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+};
+
+static inline bool is_leap_year(unsigned int year)
+{
+	return (!(year % 4) && (year % 100)) || !(year % 400);
+}
+
+static long long tst_mktime(const unsigned int year0, const unsigned int mon0,
+		const unsigned int day, const unsigned int hour,
+		const unsigned int min, const unsigned int sec)
+{
+	unsigned int mon = mon0, year = year0;
+
+	/* 1..12 -> 11,12,1..10 */
+	mon -= 2;
+	if (0 >= (int) (mon)) {
+		mon += 12;	/* Puts Feb last since it has leap day */
+		year -= 1;
+	}
+
+	return ((((long long)
+		(year/4 - year/100 + year/400 + 367*mon/12 + day) +
+		year*365 - 719499
+		)*24 + hour /* now have hours - midnight tomorrow handled here */
+		)*60 + min /* now have minutes */
+		)*60 + sec; /* finally seconds */
+}
+
+/*
+ * The number of days in the month.
+ */
+static int rtc_month_days(unsigned int month, unsigned int year)
+{
+	return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
+}
+
+/*
+ * tst_rtc_time_to_tm - Converts time_t to rtc_time.
+ * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
+ */
+void tst_rtc_time_to_tm(long long time, struct rtc_time *tm)
+{
+	unsigned int month, year, secs;
+	int days;
+
+	/* time must be positive */
+	days = time / 86400;
+	secs = time % 86400;
+
+	/* day of the week, 1970-01-01 was a Thursday */
+	tm->tm_wday = (days + 4) % 7;
+
+	year = 1970 + days / 365;
+	days -= (year - 1970) * 365
+		+ LEAPS_THRU_END_OF(year - 1)
+		- LEAPS_THRU_END_OF(1970 - 1);
+	while (days < 0) {
+		year -= 1;
+		days += 365 + is_leap_year(year);
+	}
+	tm->tm_year = year - 1900;
+	tm->tm_yday = days + 1;
+
+	for (month = 0; month < 11; month++) {
+		int newdays;
+
+		newdays = days - rtc_month_days(month, year);
+		if (newdays < 0)
+			break;
+		days = newdays;
+	}
+	tm->tm_mon = month;
+	tm->tm_mday = days + 1;
+
+	tm->tm_hour = secs / 3600;
+	secs -= tm->tm_hour * 3600;
+	tm->tm_min = secs / 60;
+	tm->tm_sec = secs - tm->tm_min * 60;
+
+	tm->tm_isdst = 0;
+}
+
+/*
+ * tst_rtc_tm_to_time - Converts rtc_time to time_t.
+ * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
+ */
+long long tst_rtc_tm_to_time(struct rtc_time *tm)
+{
+	return tst_mktime(((unsigned int)tm->tm_year + 1900), tm->tm_mon + 1,
+			tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+}
+
+static int rtc_supported_by_kernel(const char *rtc_dev)
+{
+	int exists = access(rtc_dev, F_OK);
+
+	if (exists < 0)
+		tst_brk(TCONF, "RTC device %s not available", rtc_dev);
+	return 0;
+}
+
+static int tst_rtc_ioctl(unsigned long request, struct rtc_time *rtc_tm)
+{
+	int ret;
+	int rtc_fd = -1;
+	static const char *rtc_dev = "/dev/rtc";
+
+	if (!rtc_supported_by_kernel(rtc_dev))
+		rtc_fd = SAFE_OPEN(rtc_dev, O_RDONLY);
+
+	ret = ioctl(rtc_fd, request, rtc_tm);
+
+	if (ret != 0)
+		return -1;
+
+	if (rtc_fd > 0)
+		SAFE_CLOSE(rtc_fd);
+
+	return 0;
+}
+
+int tst_rtc_gettime(struct rtc_time *rtc_tm)
+{
+	int ret;
+
+	ret = tst_rtc_ioctl(RTC_RD_TIME, rtc_tm);
+
+	if (ret != 0)
+		return -1;
+	return 0;
+}
+
+int tst_rtc_settime(struct rtc_time *rtc_tm)
+{
+	int ret;
+
+	ret = tst_rtc_ioctl(RTC_SET_TIME, rtc_tm);
+
+	if (ret != 0)
+		return -1;
+	return 0;
+}
-- 
2.25.1