rtc: rv3028: ensure ram configuration registers are saved

If RV3028_CTRL1_EERD is not set (this is the default), the RTC will refresh
the RAM configuration registers from the EEPROM at midnight. It is
necessary to save the RAM registers back to EEPROM after modifying them.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201009153101.721149-4-alexandre.belloni@bootlin.com

drivers/rtc/rtc-rv3028.c

@@ -71,6 +71,7 @@
 
 #define RV3028_EVT_CTRL_TSR		BIT(2)
 
+#define RV3028_EEPROM_CMD_UPDATE	0x11
 #define RV3028_EEPROM_CMD_WRITE		0x21
 #define RV3028_EEPROM_CMD_READ		0x22
 
@@ -209,6 +210,50 @@ static int rv3028_enter_eerd(struct rv3028_data *rv3028, u32 *eerd)
 	return 0;
 }
 
+static int rv3028_update_eeprom(struct rv3028_data *rv3028, u32 eerd)
+{
+	u32 status;
+	int ret;
+
+	ret = regmap_write(rv3028->regmap, RV3028_EEPROM_CMD, 0x0);
+	if (ret)
+		goto exit_eerd;
+
+	ret = regmap_write(rv3028->regmap, RV3028_EEPROM_CMD, RV3028_EEPROM_CMD_UPDATE);
+	if (ret)
+		goto exit_eerd;
+
+	usleep_range(63000, RV3028_EEBUSY_TIMEOUT);
+
+	ret = regmap_read_poll_timeout(rv3028->regmap, RV3028_STATUS, status,
+				       !(status & RV3028_STATUS_EEBUSY),
+				       RV3028_EEBUSY_POLL, RV3028_EEBUSY_TIMEOUT);
+
+exit_eerd:
+	rv3028_exit_eerd(rv3028, eerd);
+
+	return ret;
+}
+
+static int rv3028_update_cfg(struct rv3028_data *rv3028, unsigned int reg,
+			     unsigned int mask, unsigned int val)
+{
+	u32 eerd;
+	int ret;
+
+	ret = rv3028_enter_eerd(rv3028, &eerd);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(rv3028->regmap, reg, mask, val);
+	if (ret) {
+		rv3028_exit_eerd(rv3028, eerd);
+		return ret;
+	}
+
+	return rv3028_update_eeprom(rv3028, eerd);
+}
+
 static irqreturn_t rv3028_handle_irq(int irq, void *dev_id)
 {
 	struct rv3028_data *rv3028 = dev_id;
@@ -442,17 +487,32 @@ static int rv3028_read_offset(struct device *dev, long *offset)
 static int rv3028_set_offset(struct device *dev, long offset)
 {
 	struct rv3028_data *rv3028 = dev_get_drvdata(dev);
+	u32 eerd;
 	int ret;
 
 	offset = clamp(offset, -244141L, 243187L) * 1000;
 	offset = DIV_ROUND_CLOSEST(offset, OFFSET_STEP_PPT);
 
+	ret = rv3028_enter_eerd(rv3028, &eerd);
+	if (ret)
+		return ret;
+
 	ret = regmap_write(rv3028->regmap, RV3028_OFFSET, offset >> 1);
 	if (ret < 0)
-		return ret;
+		goto exit_eerd;
+
+	ret = regmap_update_bits(rv3028->regmap, RV3028_BACKUP, BIT(7),
+				 offset << 7);
+	if (ret < 0)
+		goto exit_eerd;
+
+	return rv3028_update_eeprom(rv3028, eerd);
+
+exit_eerd:
+	rv3028_exit_eerd(rv3028, eerd);
+
+	return ret;
 
-	return regmap_update_bits(rv3028->regmap, RV3028_BACKUP, BIT(7),
-				  offset << 7);
 }
 
 static int rv3028_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
@@ -634,8 +694,8 @@ static int rv3028_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
 		if (clkout_rates[i] == rate)
-			return regmap_write(rv3028->regmap, RV3028_CLKOUT,
-					    RV3028_CLKOUT_CLKSY | enabled | i);
+			return rv3028_update_cfg(rv3028, RV3028_CLKOUT, 0xff,
+						 RV3028_CLKOUT_CLKSY | enabled | i);
 
 	return -EINVAL;
 }
@@ -810,10 +870,8 @@ static int rv3028_probe(struct i2c_client *client)
 				break;
 
 		if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
-			ret = regmap_update_bits(rv3028->regmap, RV3028_BACKUP,
-						 RV3028_BACKUP_TCE |
-						 RV3028_BACKUP_TCR_MASK,
-						 RV3028_BACKUP_TCE | i);
+			ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, RV3028_BACKUP_TCE |
+						 RV3028_BACKUP_TCR_MASK, RV3028_BACKUP_TCE | i);
 			if (ret)
 				return ret;
 		} else {