regulator: ad5398: change enable bit name to improve readibility

The mask name AD5398_CURRENT_EN_MASK is misleading, as it implies that
setting bit 16 of the AD5398 enables current flow. In fact, setting this
bit prevents current flow, due to this bit being a software power down
control. This bit is referred to as "soft power down" in the datasheet.
As such, change the name of the bit and modify its use in the driver to
make the regulator more intuitively usable.

(When calling ad5398_enable, current will start flowing, and vice
versa).

Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Link: https://patch.msgid.link/20250128173143.959600-2-isaac.scott@ideasonboard.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: ijgscott

drivers/regulator/ad5398.c

@@ -15,7 +15,7 @@
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 
-#define AD5398_CURRENT_EN_MASK	0x8000
+#define AD5398_SW_POWER_DOWN	BIT(16)
 
 struct ad5398_chip_info {
 	struct i2c_client *client;
@@ -113,7 +113,7 @@ static int ad5398_set_current_limit(struct regulator_dev *rdev, int min_uA, int
 
 	/* prepare register data */
 	selector = (selector << chip->current_offset) & chip->current_mask;
-	data = (unsigned short)selector | (data & AD5398_CURRENT_EN_MASK);
+	data = (unsigned short)selector | (data & AD5398_SW_POWER_DOWN);
 
 	/* write the new current value back as well as enable bit */
 	ret = ad5398_write_reg(client, data);
@@ -132,10 +132,10 @@ static int ad5398_is_enabled(struct regulator_dev *rdev)
 	if (ret < 0)
 		return ret;
 
-	if (data & AD5398_CURRENT_EN_MASK)
-		return 1;
-	else
+	if (data & AD5398_SW_POWER_DOWN)
 		return 0;
+	else
+		return 1;
 }
 
 static int ad5398_enable(struct regulator_dev *rdev)
@@ -149,10 +149,10 @@ static int ad5398_enable(struct regulator_dev *rdev)
 	if (ret < 0)
 		return ret;
 
-	if (data & AD5398_CURRENT_EN_MASK)
+	if (!(data & AD5398_SW_POWER_DOWN))
 		return 0;
 
-	data |= AD5398_CURRENT_EN_MASK;
+	data &= ~AD5398_SW_POWER_DOWN;
 
 	ret = ad5398_write_reg(client, data);
 
@@ -170,10 +170,10 @@ static int ad5398_disable(struct regulator_dev *rdev)
 	if (ret < 0)
 		return ret;
 
-	if (!(data & AD5398_CURRENT_EN_MASK))
+	if (data & AD5398_SW_POWER_DOWN)
 		return 0;
 
-	data &= ~AD5398_CURRENT_EN_MASK;
+	data |= AD5398_SW_POWER_DOWN;
 
 	ret = ad5398_write_reg(client, data);