staging:iio:ad7150: fix threshold mode config bit

According to the AD7150 configuration register description, bit 7 assumes
value 1 when the threshold mode is fixed and 0 when it is adaptive,
however, the operation that identifies this mode was considering the
opposite values.

This patch renames the boolean variable to describe it correctly and
properly replaces it in the places where it is used.

Fixes: 531efd6a ("staging:iio:adc:ad7150: chan_spec conv + i2c_smbus commands + drop unused poweroff timeout control.")
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/cdc/ad7150.c

@@ -5,6 +5,7 @@
  * Copyright 2010-2011 Analog Devices Inc.
  */
 
+#include <linux/bitfield.h>
 #include <linux/interrupt.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
@@ -130,7 +131,7 @@ static int ad7150_read_event_config(struct iio_dev *indio_dev,
 {
 	int ret;
 	u8 threshtype;
-	bool adaptive;
+	bool thrfixed;
 	struct ad7150_chip_info *chip = iio_priv(indio_dev);
 
 	ret = i2c_smbus_read_byte_data(chip->client, AD7150_CFG);
@@ -138,21 +139,23 @@ static int ad7150_read_event_config(struct iio_dev *indio_dev,
 		return ret;
 
 	threshtype = (ret >> 5) & 0x03;
-	adaptive = !!(ret & 0x80);
+
+	/*check if threshold mode is fixed or adaptive*/
+	thrfixed = FIELD_GET(AD7150_CFG_FIX, ret);
 
 	switch (type) {
 	case IIO_EV_TYPE_MAG_ADAPTIVE:
 		if (dir == IIO_EV_DIR_RISING)
-			return adaptive && (threshtype == 0x1);
-		return adaptive && (threshtype == 0x0);
+			return !thrfixed && (threshtype == 0x1);
+		return !thrfixed && (threshtype == 0x0);
 	case IIO_EV_TYPE_THRESH_ADAPTIVE:
 		if (dir == IIO_EV_DIR_RISING)
-			return adaptive && (threshtype == 0x3);
-		return adaptive && (threshtype == 0x2);
+			return !thrfixed && (threshtype == 0x3);
+		return !thrfixed && (threshtype == 0x2);
 	case IIO_EV_TYPE_THRESH:
 		if (dir == IIO_EV_DIR_RISING)
-			return !adaptive && (threshtype == 0x1);
-		return !adaptive && (threshtype == 0x0);
+			return thrfixed && (threshtype == 0x1);
+		return thrfixed && (threshtype == 0x0);
 	default:
 		break;
 	}