rtc: rzn1: reduce register access

This RTC has special 32bit registers which return multiple of the same
8bit registers at once. Use these to minimize register access. Also, do
the to/from BCD conversions right away, so 'tm' always contains values
as described in time.h.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20241122101448.4374-3-wsa+renesas@sang-engineering.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: Wolfram Sang

drivers/rtc/rtc-rzn1.c

@@ -35,13 +35,13 @@
 #define   RZN1_RTC_CTL2_WUST BIT(5)
 #define   RZN1_RTC_CTL2_STOPPED (RZN1_RTC_CTL2_WAIT | RZN1_RTC_CTL2_WST)
 
-#define RZN1_RTC_SEC 0x14
-#define RZN1_RTC_MIN 0x18
-#define RZN1_RTC_HOUR 0x1c
-#define RZN1_RTC_WEEK 0x20
-#define RZN1_RTC_DAY 0x24
-#define RZN1_RTC_MONTH 0x28
-#define RZN1_RTC_YEAR 0x2c
+#define RZN1_RTC_TIME 0x30
+#define RZN1_RTC_TIME_MIN_SHIFT 8
+#define RZN1_RTC_TIME_HOUR_SHIFT 16
+#define RZN1_RTC_CAL 0x34
+#define RZN1_RTC_CAL_DAY_SHIFT 8
+#define RZN1_RTC_CAL_MON_SHIFT 16
+#define RZN1_RTC_CAL_YEAR_SHIFT 24
 
 #define RZN1_RTC_SUBU 0x38
 #define   RZN1_RTC_SUBU_DEV BIT(7)
@@ -52,12 +52,8 @@
 #define RZN1_RTC_ALW 0x48
 
 #define RZN1_RTC_SECC 0x4c
-#define RZN1_RTC_MINC 0x50
-#define RZN1_RTC_HOURC 0x54
-#define RZN1_RTC_WEEKC 0x58
-#define RZN1_RTC_DAYC 0x5c
-#define RZN1_RTC_MONTHC 0x60
-#define RZN1_RTC_YEARC 0x64
+#define RZN1_RTC_TIMEC 0x68
+#define RZN1_RTC_CALC 0x6c
 
 struct rzn1_rtc {
 	struct rtc_device *rtcdev;
@@ -66,13 +62,18 @@ struct rzn1_rtc {
 
 static void rzn1_rtc_get_time_snapshot(struct rzn1_rtc *rtc, struct rtc_time *tm)
 {
-	tm->tm_sec = readl(rtc->base + RZN1_RTC_SECC);
-	tm->tm_min = readl(rtc->base + RZN1_RTC_MINC);
-	tm->tm_hour = readl(rtc->base + RZN1_RTC_HOURC);
-	tm->tm_wday = readl(rtc->base + RZN1_RTC_WEEKC);
-	tm->tm_mday = readl(rtc->base + RZN1_RTC_DAYC);
-	tm->tm_mon = readl(rtc->base + RZN1_RTC_MONTHC);
-	tm->tm_year = readl(rtc->base + RZN1_RTC_YEARC);
+	u32 val;
+
+	val = readl(rtc->base + RZN1_RTC_TIMEC);
+	tm->tm_sec = bcd2bin(val);
+	tm->tm_min = bcd2bin(val >> RZN1_RTC_TIME_MIN_SHIFT);
+	tm->tm_hour = bcd2bin(val >> RZN1_RTC_TIME_HOUR_SHIFT);
+
+	val = readl(rtc->base + RZN1_RTC_CALC);
+	tm->tm_wday = val & 0x0f;
+	tm->tm_mday = bcd2bin(val >> RZN1_RTC_CAL_DAY_SHIFT);
+	tm->tm_mon = bcd2bin(val >> RZN1_RTC_CAL_MON_SHIFT) - 1;
+	tm->tm_year = bcd2bin(val >> RZN1_RTC_CAL_YEAR_SHIFT) + 100;
 }
 
 static int rzn1_rtc_read_time(struct device *dev, struct rtc_time *tm)
@@ -90,16 +91,9 @@ static int rzn1_rtc_read_time(struct device *dev, struct rtc_time *tm)
 
 	rzn1_rtc_get_time_snapshot(rtc, tm);
 	secs = readl(rtc->base + RZN1_RTC_SECC);
-	if (tm->tm_sec != secs)
+	if (tm->tm_sec != bcd2bin(secs))
 		rzn1_rtc_get_time_snapshot(rtc, tm);
 
-	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) - 1;
-	tm->tm_year = bcd2bin(tm->tm_year) + 100;
-
 	return 0;
 }
 
@@ -109,13 +103,6 @@ static int rzn1_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	u32 val;
 	int ret;
 
-	tm->tm_sec = bin2bcd(tm->tm_sec);
-	tm->tm_min = bin2bcd(tm->tm_min);
-	tm->tm_hour = bin2bcd(tm->tm_hour);
-	tm->tm_mday = bin2bcd(tm->tm_mday);
-	tm->tm_mon = bin2bcd(tm->tm_mon + 1);
-	tm->tm_year = bin2bcd(tm->tm_year - 100);
-
 	val = readl(rtc->base + RZN1_RTC_CTL2);
 	if (!(val & RZN1_RTC_CTL2_STOPPED)) {
 		/* Hold the counter if it was counting up */
@@ -129,13 +116,17 @@ static int rzn1_rtc_set_time(struct device *dev, struct rtc_time *tm)
 			return ret;
 	}
 
-	writel(tm->tm_sec, rtc->base + RZN1_RTC_SEC);
-	writel(tm->tm_min, rtc->base + RZN1_RTC_MIN);
-	writel(tm->tm_hour, rtc->base + RZN1_RTC_HOUR);
-	writel(tm->tm_wday, rtc->base + RZN1_RTC_WEEK);
-	writel(tm->tm_mday, rtc->base + RZN1_RTC_DAY);
-	writel(tm->tm_mon, rtc->base + RZN1_RTC_MONTH);
-	writel(tm->tm_year, rtc->base + RZN1_RTC_YEAR);
+	val = bin2bcd(tm->tm_sec);
+	val |= bin2bcd(tm->tm_min) << RZN1_RTC_TIME_MIN_SHIFT;
+	val |= bin2bcd(tm->tm_hour) << RZN1_RTC_TIME_HOUR_SHIFT;
+	writel(val, rtc->base + RZN1_RTC_TIME);
+
+	val = tm->tm_wday;
+	val |= bin2bcd(tm->tm_mday) << RZN1_RTC_CAL_DAY_SHIFT;
+	val |= bin2bcd(tm->tm_mon + 1) << RZN1_RTC_CAL_MON_SHIFT;
+	val |= bin2bcd(tm->tm_year - 100) << RZN1_RTC_CAL_YEAR_SHIFT;
+	writel(val, rtc->base + RZN1_RTC_CAL);
+
 	writel(0, rtc->base + RZN1_RTC_CTL2);
 
 	return 0;