Quoting victor.duicu@xxxxxxxxxxxxx (2024-10-15 13:24:41)
> From: Victor Duicu <victor.duicu@xxxxxxxxxxxxx>
>
> This patch implements ACPI support to Microchip pac1921.
> The driver can read shunt resistor value and label from ACPI table.
>
> Signed-off-by: Victor Duicu <victor.duicu@xxxxxxxxxxxxx>
> ---
>
> The patch was tested on minnowboard and sama5.
>
> Differences related to previous versions:
> v4:
> - change name of pac1921_shunt_is_valid to pac1921_shunt_is_invalid.
> - fix coding style.
> - in pac1921_parse_of_fw change back to device_property_read_u32.
>
> v3:
> - simplify and make inline function pac1921_shunt_is_valid. Make argument u64.
> - fix link to DSM documentation.
> - in pac1921_match_acpi_device and pac1921_parse_of_fw, the shunt value is
> read as u64.
> - in pac1921_parse_of_fw remove code for reading label value from
> devicetree.
> - in pac1921_write_shunt_resistor cast the multiply result to u64 in order
> to fix overflow.
>
> v2:
> - remove name variable from priv. Driver reads label attribute with
> sysfs.
> - define pac1921_shunt_is_valid function.
> - move default assignments in pac1921_probe to original position.
> - roll back coding style changes.
> - add documentation for DSM(the linked document was used as reference).
> - remove acpi_match_device in pac1921_match_acpi_device.
> - remove unnecessary null assignment and comment.
> - change name of function pac1921_match_of_device to
> pac1921_parse_of_fw.
>
> v1:
> - initial version for review.
>
> drivers/iio/adc/pac1921.c | 104 +++++++++++++++++++++++++++++++++-----
> 1 file changed, 90 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/iio/adc/pac1921.c b/drivers/iio/adc/pac1921.c
> index a96fae546bc1..8b5127b7ee3c 100644
> --- a/drivers/iio/adc/pac1921.c
> +++ b/drivers/iio/adc/pac1921.c
> @@ -67,6 +67,10 @@ enum pac1921_mxsl {
> #define PAC1921_DEFAULT_DI_GAIN 0 /* 2^(value): 1x gain (HW default) */
> #define PAC1921_DEFAULT_NUM_SAMPLES 0 /* 2^(value): 1 sample (HW default) */
>
> +#define PAC1921_ACPI_GET_UOHMS_VALS 0
> +#define PAC1921_ACPI_GET_LABEL 1
> +#define PAC1921_DSM_UUID "f7bb9932-86ee-4516-a236-7a7a742e55cb"
> +
> /*
> * Pre-computed scale factors for BUS voltage
> * format: IIO_VAL_INT_PLUS_NANO
> @@ -204,6 +208,11 @@ struct pac1921_priv {
> } scan;
> };
>
> +static inline bool pac1921_shunt_is_invalid(u64 shunt_val)
> +{
> + return (shunt_val == 0 || shunt_val > INT_MAX);
> +}
> +
> /*
> * Check if first integration after configuration update has completed.
> *
> @@ -792,13 +801,13 @@ static ssize_t pac1921_write_shunt_resistor(struct iio_dev *indio_dev,
> if (ret)
> return ret;
>
> - rshunt_uohm = val * MICRO + val_fract;
> - if (rshunt_uohm == 0 || rshunt_uohm > INT_MAX)
> + rshunt_uohm = (u64)val * MICRO + val_fract;
> + if (pac1921_shunt_is_invalid(rshunt_uohm))
> return -EINVAL;
>
> guard(mutex)(&priv->lock);
>
> - priv->rshunt_uohm = rshunt_uohm;
> + priv->rshunt_uohm = (u32)rshunt_uohm;
This explicit cast seems unnecessary (note the similar assignment in the
pac1921_match_acpi_device() that doesn't use the explicit cast).
Beside that the rest of the patch looks good to me.
Acked-by: Matteo Martelli <matteomartelli3@xxxxxxxxx>
Best regards,
Matteo Martelli
