linux-kernel - Re: [PATCH 3/3] iio: frequency: adf4371: add ref doubler

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Message-ID: <20241208164242.013ac089@jic23-huawei>
Date: Sun, 8 Dec 2024 16:42:42 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>
Cc: <robh@...nel.org>, <conor+dt@...nel.org>, <linux-iio@...r.kernel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH 3/3] iio: frequency: adf4371: add ref doubler

On Fri, 6 Dec 2024 17:22:06 +0200
Antoniu Miclaus <antoniu.miclaus@...log.com> wrote:

> Add support for the reference doubler.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
> ---
>  drivers/iio/frequency/adf4371.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/frequency/adf4371.c b/drivers/iio/frequency/adf4371.c
> index 55bee06fb42d..dc01f2aafb9a 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 */
> @@ -480,7 +485,7 @@ 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;
>  	bool ref_diff_en;
>  	int ret;
>  
> @@ -516,6 +521,10 @@ static int adf4371_setup(struct adf4371_state *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_REFIN_MODE_MASK,
>  				 ADF4371_REFIN_MODE(ref_diff_en));
> @@ -531,7 +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);
No need for brackets on the previous line.

Otherwise this looks good to me.
>  	} while (st->fpfd > ADF4371_MAX_FREQ_PFD);
>  
>  	/* Calculate Timeouts */