[PATCH 3/4] rtc: rx8025: set date in a single i2c transaction

[Mathew McBride]

The RX8025/RX8035 does not like having it's time registers
set byte-by-byte in separate I2C transactions.

>From the note at the top of the file, it appears
target-dependent workarounds have been used in the
past for this.

Resolve this by setting the time registers in a single
I2C transaction.

As part of this, also ensure the '24/12' flag in the RTC
is reset before writing the date (instead of after), otherwise
the RX8035 will clear the seconds and minutes registers.

Tested on Traverse Ten64 (NXP LS1088A) with RX8035.

Signed-off-by: Mathew McBride <matt at traverse.com.au>
---
 drivers/rtc/rx8025.c | 44 +++++++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/drivers/rtc/rx8025.c b/drivers/rtc/rx8025.c
index 09bf365f63..9423a1bb82 100644
--- a/drivers/rtc/rx8025.c
+++ b/drivers/rtc/rx8025.c
@@ -39,6 +39,7 @@ enum rx_model {
 #define RTC_DATE_REG_ADDR	0x04
 #define RTC_MON_REG_ADDR	0x05
 #define RTC_YR_REG_ADDR		0x06
+#define RTC_OFFSET_REG_ADDR	0x07
 
 #define RTC_CTL1_REG_ADDR	0x0e
 #define RTC_CTL2_REG_ADDR	0x0f
@@ -152,6 +153,19 @@ static int rx8025_rtc_get(struct udevice *dev, struct rtc_time *tmp)
  */
 static int rx8025_rtc_set(struct udevice *dev, const struct rtc_time *tmp)
 {
+	/* To work around the read/write cycle issue mentioned
+	 * at the top of this file, write all the time registers
+	 * in one I2C transaction
+	 */
+	u8 write_op[8];
+
+	/* 2412 flag must be set before doing a RTC write,
+	 * otherwise the seconds and minute register
+	 * will be cleared when the flag is set
+	 */
+	if (rtc_write(dev, RTC_CTL1_REG_ADDR, RTC_CTL1_BIT_2412))
+		return -EIO;
+
 	DEBUGR("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 	       tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 	       tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
@@ -159,28 +173,16 @@ static int rx8025_rtc_set(struct udevice *dev, const struct rtc_time *tmp)
 	if (tmp->tm_year < 1970 || tmp->tm_year > 2069)
 		printf("WARNING: year should be between 1970 and 2069!\n");
 
-	if (rtc_write(dev, RTC_YR_REG_ADDR, bin2bcd(tmp->tm_year % 100)))
-		return -EIO;
-
-	if (rtc_write(dev, RTC_MON_REG_ADDR, bin2bcd(tmp->tm_mon)))
-		return -EIO;
-
-	if (rtc_write(dev, RTC_DAY_REG_ADDR, bin2bcd(tmp->tm_wday)))
-		return -EIO;
-
-	if (rtc_write(dev, RTC_DATE_REG_ADDR, bin2bcd(tmp->tm_mday)))
-		return -EIO;
-
-	if (rtc_write(dev, RTC_HR_REG_ADDR, bin2bcd(tmp->tm_hour)))
-		return -EIO;
-
-	if (rtc_write(dev, RTC_MIN_REG_ADDR, bin2bcd(tmp->tm_min)))
-		return -EIO;
-
-	if (rtc_write(dev, RTC_SEC_REG_ADDR, bin2bcd(tmp->tm_sec)))
-		return -EIO;
+	write_op[RTC_SEC_REG_ADDR]  = bin2bcd(tmp->tm_sec);
+	write_op[RTC_MIN_REG_ADDR]  = bin2bcd(tmp->tm_min);
+	write_op[RTC_HR_REG_ADDR]   = bin2bcd(tmp->tm_hour);
+	write_op[RTC_DAY_REG_ADDR]	= bin2bcd(tmp->tm_wday);
+	write_op[RTC_DATE_REG_ADDR]	= bin2bcd(tmp->tm_mday);
+	write_op[RTC_MON_REG_ADDR]  = bin2bcd(tmp->tm_mon);
+	write_op[RTC_YR_REG_ADDR]	= bin2bcd(tmp->tm_year % 100);
+	write_op[RTC_OFFSET_REG_ADDR] = 0;
 
-	return rtc_write(dev, RTC_CTL1_REG_ADDR, RTC_CTL1_BIT_2412);
+	return dm_i2c_write(dev, 0, &write_op[0], 8);
 }
 
 /*
-- 
2.30.1