[PATCH v3 1/1] rtc: nuvoton: Compatible with NCT3015Y-R and NCT3018Y-R

[Mia Lin]

- In probe,
  If part number is NCT3018Y-R, only set HF bit to 24-Hour format.
  Else, do nothing
- In set_time,
  If part number is NCT3018Y-R && TWO bit is 0,
    change TWO bit to 1, and restore TWO bit after updating time.

Signed-off-by: Mia Lin <mimi05633 at gmail.com>
---
 drivers/rtc/rtc-nct3018y.c | 63 ++++++++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 9 deletions(-)

diff --git a/drivers/rtc/rtc-nct3018y.c b/drivers/rtc/rtc-nct3018y.c
index a4e3f924837e..bac1e3fbbbcd 100644
--- a/drivers/rtc/rtc-nct3018y.c
+++ b/drivers/rtc/rtc-nct3018y.c
@@ -23,6 +23,7 @@
 #define NCT3018Y_REG_CTRL	0x0A /* timer control */
 #define NCT3018Y_REG_ST		0x0B /* status */
 #define NCT3018Y_REG_CLKO	0x0C /* clock out */
+#define NCT3018Y_REG_PART	0x21 /* part info */
 
 #define NCT3018Y_BIT_AF		BIT(7)
 #define NCT3018Y_BIT_ST		BIT(7)
@@ -37,6 +38,7 @@
 #define NCT3018Y_REG_BAT_MASK		0x07
 #define NCT3018Y_REG_CLKO_F_MASK	0x03 /* frequenc mask */
 #define NCT3018Y_REG_CLKO_CKE		0x80 /* clock out enabled */
+#define NCT3018Y_REG_PART_NCT3018Y	0x02
 
 struct nct3018y {
 	struct rtc_device *rtc;
@@ -52,7 +54,7 @@ static int nct3018y_set_alarm_mode(struct i2c_client *client, bool on)
 
 	dev_dbg(&client->dev, "%s:on:%d\n", __func__, on);
 
-	flags =  i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
+	flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
 	if (flags < 0) {
 		dev_dbg(&client->dev,
 			"Failed to read NCT3018Y_REG_CTRL\n");
@@ -109,8 +111,10 @@ static int nct3018y_get_alarm_mode(struct i2c_client *client, unsigned char *ala
 		*alarm_flag = flags & NCT3018Y_BIT_AF;
 	}
 
-	dev_dbg(&client->dev, "%s:alarm_enable:%x alarm_flag:%x\n",
-		__func__, *alarm_enable, *alarm_flag);
+	if (alarm_enable && alarm_flag) {
+		dev_dbg(&client->dev, "%s:alarm_enable:%x alarm_flag:%x\n",
+			__func__, *alarm_enable, *alarm_flag);
+	}
 
 	return 0;
 }
@@ -178,7 +182,30 @@ static int nct3018y_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned char buf[4] = {0};
-	int err;
+	int err, part_num, flags, restore_flags = 0;
+
+	part_num = i2c_smbus_read_byte_data(client, NCT3018Y_REG_PART);
+	if (part_num < 0) {
+		dev_dbg(&client->dev, "%s: read error\n", __func__);
+		return part_num;
+	}
+
+	flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
+	if (flags < 0) {
+		dev_dbg(&client->dev, "%s: read error\n", __func__);
+		return flags;
+	}
+
+	/* Check and set TWO bit */
+	if ((part_num & NCT3018Y_REG_PART_NCT3018Y) && !(flags & NCT3018Y_BIT_TWO)) {
+		restore_flags = 1;
+		flags |= NCT3018Y_BIT_TWO;
+		err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
+		if (err < 0) {
+			dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL\n");
+			return err;
+		}
+	}
 
 	buf[0] = bin2bcd(tm->tm_sec);
 	err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_SC, buf[0]);
@@ -212,6 +239,18 @@ static int nct3018y_rtc_set_time(struct device *dev, struct rtc_time *tm)
 		return -EIO;
 	}
 
+	/* Restore TWO bit */
+	if (restore_flags) {
+		if (part_num & NCT3018Y_REG_PART_NCT3018Y)
+			flags &= ~NCT3018Y_BIT_TWO;
+
+		err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
+		if (err < 0) {
+			dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL\n");
+			return err;
+		}
+	}
+
 	return err;
 }
 
@@ -479,11 +518,17 @@ static int nct3018y_probe(struct i2c_client *client)
 		dev_dbg(&client->dev, "%s: NCT3018Y_BIT_TWO is set\n", __func__);
 	}
 
-	flags = NCT3018Y_BIT_TWO;
-	err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
-	if (err < 0) {
-		dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL\n");
-		return err;
+	flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_PART);
+	if (flags < 0) {
+		dev_dbg(&client->dev, "%s: read error\n", __func__);
+		return flags;
+	} else if (flags & NCT3018Y_REG_PART_NCT3018Y) {
+		flags = NCT3018Y_BIT_HF;
+		err = i2c_smbus_write_byte_data(client, NCT3018Y_REG_CTRL, flags);
+		if (err < 0) {
+			dev_dbg(&client->dev, "Unable to write NCT3018Y_REG_CTRL\n");
+			return err;
+		}
 	}
 
 	flags = 0;
-- 
2.17.1