rtc: s3c: Extract read/write IO into separate functions

Create dedicated functions for I/O operations and BCD conversion. It can
be useful to separate those from representation conversion and other
stuff found in RTC callbacks.

This patch does not introduce any functional changes, it's merely
refactoring change.
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20211021202256.28517-3-semen.protsenko@linaro.org

drivers/rtc/rtc-s3c.c

@@ -127,10 +127,9 @@ static int s3c_rtc_setaie(struct device *dev, unsigned int enabled)
 	return ret;
 }
 
-/* Time read/write */
-static int s3c_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
+/* Read time from RTC and convert it from BCD */
+static int s3c_rtc_read_time(struct s3c_rtc *info, struct rtc_time *tm)
 {
-	struct s3c_rtc *info = dev_get_drvdata(dev);
 	unsigned int have_retried = 0;
 	int ret;
 
@@ -139,54 +138,40 @@ static int s3c_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
 		return ret;
 
 retry_get_time:
-	rtc_tm->tm_min  = readb(info->base + S3C2410_RTCMIN);
-	rtc_tm->tm_hour = readb(info->base + S3C2410_RTCHOUR);
-	rtc_tm->tm_mday = readb(info->base + S3C2410_RTCDATE);
-	rtc_tm->tm_mon  = readb(info->base + S3C2410_RTCMON);
-	rtc_tm->tm_year = readb(info->base + S3C2410_RTCYEAR);
-	rtc_tm->tm_sec  = readb(info->base + S3C2410_RTCSEC);
-
-	/* the only way to work out whether the system was mid-update
+	tm->tm_min  = readb(info->base + S3C2410_RTCMIN);
+	tm->tm_hour = readb(info->base + S3C2410_RTCHOUR);
+	tm->tm_mday = readb(info->base + S3C2410_RTCDATE);
+	tm->tm_mon  = readb(info->base + S3C2410_RTCMON);
+	tm->tm_year = readb(info->base + S3C2410_RTCYEAR);
+	tm->tm_sec  = readb(info->base + S3C2410_RTCSEC);
+
+	/*
+	 * The only way to work out whether the system was mid-update
 	 * when we read it is to check the second counter, and if it
 	 * is zero, then we re-try the entire read
 	 */
-
-	if (rtc_tm->tm_sec == 0 && !have_retried) {
+	if (tm->tm_sec == 0 && !have_retried) {
 		have_retried = 1;
 		goto retry_get_time;
 	}
 
-	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
-	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
-	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
-	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
-	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
-	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
-
 	s3c_rtc_disable_clk(info);
 
-	rtc_tm->tm_year += 100;
-	rtc_tm->tm_mon -= 1;
+	tm->tm_sec  = bcd2bin(tm->tm_sec);
+	tm->tm_min  = bcd2bin(tm->tm_min);
+	tm->tm_hour = bcd2bin(tm->tm_hour);
+	tm->tm_mday = bcd2bin(tm->tm_mday);
+	tm->tm_mon  = bcd2bin(tm->tm_mon);
+	tm->tm_year = bcd2bin(tm->tm_year);
 
-	dev_dbg(dev, "read time %ptR\n", rtc_tm);
 	return 0;
 }
 
-static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm)
+/* Convert time to BCD and write it to RTC */
+static int s3c_rtc_write_time(struct s3c_rtc *info, const struct rtc_time *tm)
 {
-	struct s3c_rtc *info = dev_get_drvdata(dev);
-	int year = tm->tm_year - 100;
 	int ret;
 
-	dev_dbg(dev, "set time %ptR\n", tm);
-
-	/* we get around y2k by simply not supporting it */
-
-	if (year < 0 || year >= 100) {
-		dev_err(dev, "rtc only supports 100 years\n");
-		return -EINVAL;
-	}
-
 	ret = s3c_rtc_enable_clk(info);
 	if (ret)
 		return ret;
@@ -195,14 +180,53 @@ static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm)
 	writeb(bin2bcd(tm->tm_min),  info->base + S3C2410_RTCMIN);
 	writeb(bin2bcd(tm->tm_hour), info->base + S3C2410_RTCHOUR);
 	writeb(bin2bcd(tm->tm_mday), info->base + S3C2410_RTCDATE);
-	writeb(bin2bcd(tm->tm_mon + 1), info->base + S3C2410_RTCMON);
-	writeb(bin2bcd(year), info->base + S3C2410_RTCYEAR);
+	writeb(bin2bcd(tm->tm_mon),  info->base + S3C2410_RTCMON);
+	writeb(bin2bcd(tm->tm_year), info->base + S3C2410_RTCYEAR);
 
 	s3c_rtc_disable_clk(info);
 
 	return 0;
 }
 
+static int s3c_rtc_gettime(struct device *dev, struct rtc_time *tm)
+{
+	struct s3c_rtc *info = dev_get_drvdata(dev);
+	int ret;
+
+	ret = s3c_rtc_read_time(info, tm);
+	if (ret)
+		return ret;
+
+	/* Convert internal representation to actual date/time */
+	tm->tm_year += 100;
+	tm->tm_mon -= 1;
+
+	dev_dbg(dev, "read time %ptR\n", tm);
+	return 0;
+}
+
+static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+	struct s3c_rtc *info = dev_get_drvdata(dev);
+	struct rtc_time rtc_tm = *tm;
+
+	dev_dbg(dev, "set time %ptR\n", tm);
+
+	/*
+	 * Convert actual date/time to internal representation.
+	 * We get around Y2K by simply not supporting it.
+	 */
+	rtc_tm.tm_year -= 100;
+	rtc_tm.tm_mon += 1;
+
+	if (rtc_tm.tm_year < 0 || rtc_tm.tm_year >= 100) {
+		dev_err(dev, "rtc only supports 100 years\n");
+		return -EINVAL;
+	}
+
+	return s3c_rtc_write_time(info, &rtc_tm);
+}
+
 static int s3c_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct s3c_rtc *info = dev_get_drvdata(dev);