[PATCH v3] iio: adc: spear_adc: mask SPEAR_ADC_STATUS channel and avg sample before setting register

[Rodrigo Gobbi <rodrigo.gobbi.7@gmail.com>]

avg sample info is a bit field coded inside the following
bits: 5,6,7 and 8 of a device status register.

channel num info the same, but over bits: 1, 2 and 3.

mask both values in order to avoid touching other register bits,
since the first info (avg sample), came from dt.

Signed-off-by: Rodrigo Gobbi <rodrigo.gobbi.7@gmail.com>
---
About @David comment at v2:

> For bonus points, a separate patch that cleans up and sorts the existing
> includes would be appreciated.

I`ll change that in a later moment.
Tks and regards.

Changelog:
v3: moving up include; fix indentation;
v2: https://lore.kernel.org/linux-iio/20250701213728.32064-1-rodrigo.gobbi.7@gmail.com/
v1: https://lore.kernel.org/linux-iio/20250621185301.9536-1-rodrigo.gobbi.7@gmail.com/#t
---
 drivers/iio/adc/spear_adc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/spear_adc.c b/drivers/iio/adc/spear_adc.c
index e3a865c79686..0acc65c74221 100644
--- a/drivers/iio/adc/spear_adc.c
+++ b/drivers/iio/adc/spear_adc.c
@@ -17,6 +17,7 @@
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/completion.h>
+#include <linux/bitfield.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -29,9 +30,9 @@
 
 /* Bit definitions for SPEAR_ADC_STATUS */
 #define SPEAR_ADC_STATUS_START_CONVERSION	BIT(0)
-#define SPEAR_ADC_STATUS_CHANNEL_NUM(x)		((x) << 1)
+#define SPEAR_ADC_STATUS_CHANNEL_NUM_MASK	GENMASK(3, 1)
 #define SPEAR_ADC_STATUS_ADC_ENABLE		BIT(4)
-#define SPEAR_ADC_STATUS_AVG_SAMPLE(x)		((x) << 5)
+#define SPEAR_ADC_STATUS_AVG_SAMPLE_MASK	GENMASK(8, 5)
 #define SPEAR_ADC_STATUS_VREF_INTERNAL		BIT(9)
 
 #define SPEAR_ADC_DATA_MASK		0x03ff
@@ -157,8 +158,8 @@ static int spear_adc_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&st->lock);
 
-		status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) |
-			SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) |
+		status = FIELD_PREP(SPEAR_ADC_STATUS_CHANNEL_NUM_MASK, chan->channel) |
+			FIELD_PREP(SPEAR_ADC_STATUS_AVG_SAMPLE_MASK, st->avg_samples) |
 			SPEAR_ADC_STATUS_START_CONVERSION |
 			SPEAR_ADC_STATUS_ADC_ENABLE;
 		if (st->vref_external == 0)
-- 
2.48.1