rtc: nuvoton: Compatible with NCT3015Y-R and NCT3018Y-R

The NCT3015Y-R and NCT3018Y-R use the same datasheet
    but have different topologies as follows.
- Topology (Only 1st i2c can set TWO bit and HF bit)
  In NCT3015Y-R,
    rtc 1st i2c is connected to a host CPU
    rtc 2nd i2c is connected to a BMC
  In NCT3018Y-R,
    rtc 1st i2c is connected to a BMC
    rtc 2nd i2c is connected to a host CPU
In order to be compatible with NCT3015Y-R and NCT3018Y-R,
- 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@gmail.com>
Link: https://lore.kernel.org/r/20231113103807.1036978-2-mimi05633@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-nct3018y.c b/drivers/rtc/rtc-nct3018y.c
index ed4e606be8e58d2779bd6aff148b388435770830..f488a189a4651ffead1bbcc1e4e9d3a5cd01d5df 100644 (file)
--- 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)
@@ -37,10 +38,12 @@
 #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;
        struct i2c_client *client;
+       int part_num;
 #ifdef CONFIG_COMMON_CLK
        struct clk_hw clkout_hw;
 #endif
@@ -177,8 +180,27 @@ static int nct3018y_rtc_read_time(struct device *dev, struct rtc_time *tm)
 static int nct3018y_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
        struct i2c_client *client = to_i2c_client(dev);
+       struct nct3018y *nct3018y = dev_get_drvdata(dev);
        unsigned char buf[4] = {0};
-       int err;
+       int err, flags;
+       int restore_flags = 0;
+
+       flags = i2c_smbus_read_byte_data(client, NCT3018Y_REG_CTRL);
+       if (flags < 0) {
+               dev_dbg(&client->dev, "Failed to read NCT3018Y_REG_CTRL.\n");
+               return flags;
+       }
+
+       /* Check and set TWO bit */
+       if (nct3018y->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 +234,18 @@ static int nct3018y_rtc_set_time(struct device *dev, struct rtc_time *tm)
                return -EIO;
        }
 
+       /* Restore TWO bit */
+       if (restore_flags) {
+               if (nct3018y->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 +513,17 @@ 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;
+       nct3018y->part_num = i2c_smbus_read_byte_data(client, NCT3018Y_REG_PART);
+       if (nct3018y->part_num < 0) {
+               dev_dbg(&client->dev, "Failed to read NCT3018Y_REG_PART.\n");
+               return nct3018y->part_num;
+       } else if (nct3018y->part_num == 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;