Re: [PATCH v4 3/3] iio: frequency: adf4371: add ref doubler

["Nuno Sá" <noname.nuno@gmail.com>]

On Thu, 2025-01-09 at 15:37 +0200, Antoniu Miclaus wrote:
> Add support for the reference doubler.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---

LGTM:

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

> no changes in v4.
>  drivers/iio/frequency/adf4371.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/frequency/adf4371.c b/drivers/iio/frequency/adf4371.c
> index 50450e7b5464..a57fc24a6799 100644
> --- a/drivers/iio/frequency/adf4371.c
> +++ b/drivers/iio/frequency/adf4371.c
> @@ -44,6 +44,8 @@
>  /* ADF4371_REG22 */
>  #define ADF4371_REFIN_MODE_MASK		BIT(6)
>  #define ADF4371_REFIN_MODE(x)		FIELD_PREP(ADF4371_REFIN_MODE_MASK,
> x)
> +#define ADF4371_REF_DOUB_MASK		BIT(5)
> +#define ADF4371_REF_DOUB(x)		FIELD_PREP(ADF4371_REF_DOUB_MASK, x)\
>  
>  /* ADF4371_REG24 */
>  #define ADF4371_RF_DIV_SEL_MSK		GENMASK(6, 4)
> @@ -75,6 +77,9 @@
>  #define ADF4371_MAX_FREQ_REFIN		600000000UL /* Hz */
>  #define ADF4371_MAX_FREQ_REFIN_SE	500000000UL /* Hz */
>  
> +#define ADF4371_MIN_CLKIN_DOUB_FREQ	10000000ULL /* Hz */
> +#define ADF4371_MAX_CLKIN_DOUB_FREQ	125000000ULL /* Hz */
> +
>  /* MOD1 is a 24-bit primary modulus with fixed value of 2^25 */
>  #define ADF4371_MODULUS1		33554432ULL
>  /* MOD2 is the programmable, 14-bit auxiliary fractional modulus */
> @@ -481,7 +486,7 @@ static const struct iio_info adf4371_info = {
>  static int adf4371_setup(struct adf4371_state *st)
>  {
>  	unsigned int synth_timeout = 2, timeout = 1, vco_alc_timeout = 1;
> -	unsigned int vco_band_div, tmp;
> +	unsigned int vco_band_div, tmp, ref_doubler_en = 0;
>  	int ret;
>  
>  	/* Perform a software reset */
> @@ -514,8 +519,14 @@ static int adf4371_setup(struct adf4371_state *st)
>  	    (!st->ref_diff_en && st->clkin_freq > ADF4371_MAX_FREQ_REFIN_SE))
>  		return -EINVAL;
>  
> +	if (st->clkin_freq < ADF4371_MAX_CLKIN_DOUB_FREQ &&
> +	    st->clkin_freq > ADF4371_MIN_CLKIN_DOUB_FREQ)
> +		ref_doubler_en = 1;
> +
>  	ret = regmap_update_bits(st->regmap,  ADF4371_REG(0x22),
> +				 ADF4371_REF_DOUB_MASK |
>  				 ADF4371_REFIN_MODE_MASK,
> +				 ADF4371_REF_DOUB(ref_doubler_en) |
>  				 ADF4371_REFIN_MODE(st->ref_diff_en));
>  	if (ret < 0)
>  		return ret;
> @@ -529,7 +540,8 @@ static int adf4371_setup(struct adf4371_state *st)
>  	 */
>  	do {
>  		st->ref_div_factor++;
> -		st->fpfd = st->clkin_freq / st->ref_div_factor;
> +		st->fpfd = st->clkin_freq * (1 + ref_doubler_en) /
> +			   st->ref_div_factor;
>  	} while (st->fpfd > ADF4371_MAX_FREQ_PFD);
>  
>  	/* Calculate Timeouts */