Re: [PATCH v4 2/3] iio: frequency: adf4371: add refin mode

["Nuno Sá" <noname.nuno@gmail.com>]

On Thu, 2025-01-09 at 15:37 +0200, Antoniu Miclaus wrote:
> Add support for single-ended/differential reference input mode.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---

Reviewed-by: Nuno Sa <nunbo.sa@analog.com>

> changes in v4:
>  - parse input clock depending on the name and adjust the refin mode
>    accordingly.
>  drivers/iio/frequency/adf4371.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/frequency/adf4371.c b/drivers/iio/frequency/adf4371.c
> index b27088464826..50450e7b5464 100644
> --- a/drivers/iio/frequency/adf4371.c
> +++ b/drivers/iio/frequency/adf4371.c
> @@ -41,6 +41,10 @@
>  #define ADF4371_MOD2WORD_MSK		GENMASK(5, 0)
>  #define ADF4371_MOD2WORD(x)		FIELD_PREP(ADF4371_MOD2WORD_MSK, x)
>  
> +/* ADF4371_REG22 */
> +#define ADF4371_REFIN_MODE_MASK		BIT(6)
> +#define ADF4371_REFIN_MODE(x)		FIELD_PREP(ADF4371_REFIN_MODE_MASK,
> x)
> +
>  /* ADF4371_REG24 */
>  #define ADF4371_RF_DIV_SEL_MSK		GENMASK(6, 4)
>  #define ADF4371_RF_DIV_SEL(x)		FIELD_PREP(ADF4371_RF_DIV_SEL_MSK, x)
> @@ -69,6 +73,7 @@
>  
>  #define ADF4371_MAX_FREQ_PFD		250000000UL /* Hz */
>  #define ADF4371_MAX_FREQ_REFIN		600000000UL /* Hz */
> +#define ADF4371_MAX_FREQ_REFIN_SE	500000000UL /* Hz */
>  
>  /* MOD1 is a 24-bit primary modulus with fixed value of 2^25 */
>  #define ADF4371_MODULUS1		33554432ULL
> @@ -175,6 +180,7 @@ struct adf4371_state {
>  	unsigned int mod2;
>  	unsigned int rf_div_sel;
>  	unsigned int ref_div_factor;
> +	bool ref_diff_en;
>  	u8 buf[10] __aligned(IIO_DMA_MINALIGN);
>  };
>  
> @@ -503,6 +509,17 @@ static int adf4371_setup(struct adf4371_state *st)
>  				 ADF4371_ADDR_ASC(1) |
> ADF4371_ADDR_ASC_R(1));
>  	if (ret < 0)
>  		return ret;
> +
> +	if ((st->ref_diff_en && st->clkin_freq > ADF4371_MAX_FREQ_REFIN) ||
> +	    (!st->ref_diff_en && st->clkin_freq > ADF4371_MAX_FREQ_REFIN_SE))
> +		return -EINVAL;
> +
> +	ret = regmap_update_bits(st->regmap,  ADF4371_REG(0x22),
> +				 ADF4371_REFIN_MODE_MASK,
> +				 ADF4371_REFIN_MODE(st->ref_diff_en));
> +	if (ret < 0)
> +		return ret;
> +
>  	/*
>  	 * Calculate and maximize PFD frequency
>  	 * fPFD = REFIN × ((1 + D)/(R × (1 + T)))
> @@ -572,9 +589,16 @@ static int adf4371_probe(struct spi_device *spi)
>  	indio_dev->channels = st->chip_info->channels;
>  	indio_dev->num_channels = st->chip_info->num_channels;
>  
> +	st->ref_diff_en = false;
> +
>  	st->clkin = devm_clk_get_enabled(&spi->dev, "clkin");
> -	if (IS_ERR(st->clkin))
> -		return PTR_ERR(st->clkin);
> +	if (IS_ERR(st->clkin)) {
> +		st->clkin = devm_clk_get_enabled(&spi->dev, "clkin-diff");
> +		if (IS_ERR(st->clkin))
> +			return PTR_ERR(st->clkin);
> +
> +		st->ref_diff_en = true;
> +	}
>  
>  	st->clkin_freq = clk_get_rate(st->clkin);
>