Re: [PATCH v2] iio: adc: spear_adc: mask SPEAR_ADC_STATUS channel and avg sample before setting register

[David Lechner <dlechner@baylibre.com>]

On 7/1/25 4:34 PM, Rodrigo Gobbi wrote:
> 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>
> ---
> Tks for the tip, @David, I didn`t know those macros.
> Best regards!

:-)

> 
> Changelog:
> v2: use proper bitfield macros + change at commit msg
> v1: https://lore.kernel.org/linux-iio/20250621185301.9536-1-rodrigo.gobbi.7@gmail.com/#t
> ---
>  drivers/iio/adc/spear_adc.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/spear_adc.c b/drivers/iio/adc/spear_adc.c
> index e3a865c79686..ff7fb13fe947 100644
> --- a/drivers/iio/adc/spear_adc.c
> +++ b/drivers/iio/adc/spear_adc.c
> @@ -21,6 +21,8 @@
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
>  
> +#include <linux/bitfield.h>

This should be moved up with the other non-iio includes.

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

add:
#include "linux/array_size.h"        // for ARRAY_SIZE
#include "linux/compiler_types.h"    // for __iomem
#include "linux/dev_printk.h"        // for dev_err_probe, dev_info
#include "linux/math.h"              // for DIV_ROUND_UP
#include "linux/mutex.h"             // for mutex_unlock, mutex_lock, mutex_...

remove unused:
#include <linux/device.h>
#include <linux/iio/sysfs.h>
#include <linux/kernel.h>
#include <linux/slab.h>

> +
>  /* SPEAR registers definitions */
>  #define SPEAR600_ADC_SCAN_RATE_LO(x)	((x) & 0xFFFF)
>  #define SPEAR600_ADC_SCAN_RATE_HI(x)	(((x) >> 0x10) & 0xFFFF)
> @@ -29,9 +31,9 @@
>  
>  /* 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 +159,8 @@ 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)