rtc: pcf2127: Fixed bug with rtc settings and getting error time

The previous pcf2127 RTC chip could not read and set the correct time.
When reading the data of internal registers, the read address was the
value of register plus 1. This is because this chip requires the host
to send a stop signal after setting the register address and before
reading the register data.

This patch sets the register address using dm_i2c_write and reads
the register data using the original dm_i2c_xfer in order to generate
a stop signal after the register address is set, and fixes the bug of
the original read and write time.

Signed-off-by: Biwen Li <biwen.li@nxp.com>
Signed-off-by: Chuanhua Han <chuanhua.han@nxp.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Heiko Schocher <hs@denx.de>

1 files changed, 24 insertions, 9 deletions

diff --git a/drivers/rtc/pcf2127.c b/drivers/rtc/pcf2127.c
index dcf0340b4d..f6953505a5 100644
--- a/drivers/rtc/pcf2127.c
+++ b/drivers/rtc/pcf2127.c
@@ -22,14 +22,32 @@
 #define PCF2127_REG_MO		0x08
 #define PCF2127_REG_YR		0x09
 
+static int pcf2127_read_reg(struct udevice *dev, uint offset,
+			    u8 *buffer, int len)
+{
+	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
+	struct i2c_msg msg;
+	int ret;
+
+	/* Set the address of the start register to be read */
+	ret = dm_i2c_write(dev, offset, NULL, 0);
+	if (ret < 0)
+		return ret;
+
+	/* Read register's data */
+	msg.addr = chip->chip_addr;
+	msg.flags |= I2C_M_RD;
+	msg.len = len;
+	msg.buf = buffer;
+
+	return dm_i2c_xfer(dev, &msg, 1);
+}
+
 static int pcf2127_rtc_set(struct udevice *dev, const struct rtc_time *tm)
 {
-	uchar buf[8];
+	uchar buf[7] = {0};
 	int i = 0, ret;
 
-	/* start register address */
-	buf[i++] = PCF2127_REG_SC;
-
 	/* hours, minutes and seconds */
 	buf[i++] = bin2bcd(tm->tm_sec);
 	buf[i++] = bin2bcd(tm->tm_min);
@@ -44,7 +62,7 @@ static int pcf2127_rtc_set(struct udevice *dev, const struct rtc_time *tm)
 	buf[i++] = bin2bcd(tm->tm_year % 100);
 
 	/* write register's data */
-	ret = dm_i2c_write(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
+	ret = dm_i2c_write(dev, PCF2127_REG_SC, buf, i);
 
 	return ret;
 }
@@ -54,10 +72,7 @@ static int pcf2127_rtc_get(struct udevice *dev, struct rtc_time *tm)
 	int ret = 0;
 	uchar buf[10] = { PCF2127_REG_CTRL1 };
 
-	ret = dm_i2c_write(dev, PCF2127_REG_CTRL1, buf, 1);
-	if (ret < 0)
-		return ret;
-	ret = dm_i2c_read(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
+	ret = pcf2127_read_reg(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
 	if (ret < 0)
 		return ret;