linux-kernel - Re: [PATCH v4 3/5] iio: amplifiers: hmc425a: move conversion logic

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Message-ID: <20240121170759.7e4488dd@jic23-huawei>
Date: Sun, 21 Jan 2024 17:07:59 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Dumitru Ceclan <mitrutzceclan@...il.com>
Cc: Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
 <conor+dt@...nel.org>, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, Ceclan Dumitru
 <dumitru.ceclan@...log.com>
Subject: Re: [PATCH v4 3/5] iio: amplifiers: hmc425a: move conversion logic

On Wed, 17 Jan 2024 14:51:12 +0200
Dumitru Ceclan <mitrutzceclan@...il.com> wrote:

> Move gain-dB<->code conversion logic from read_raw and write_raw to
> hmc425a_gain_dB_to_code() and hmc425a_code_to_gain_dB().
> 
> Signed-off-by: Dumitru Ceclan <mitrutzceclan@...il.com>
Some comments inline

Jonathan

> ---
>  drivers/iio/amplifiers/hmc425a.c | 102 ++++++++++++++++++-------------
>  1 file changed, 59 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/iio/amplifiers/hmc425a.c b/drivers/iio/amplifiers/hmc425a.c
> index ed4d72922696..e1162a500daf 100644
> --- a/drivers/iio/amplifiers/hmc425a.c
> +++ b/drivers/iio/amplifiers/hmc425a.c
> @@ -56,35 +56,72 @@ static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
>  	return 0;
>  }
>  
> +static int hmc425a_gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code)
> +{
> +	struct hmc425a_chip_info *inf = st->chip_info;
> +	int gain, temp;
> +
> +	if (val < 0)
> +		gain = (val * 1000) - (val2 / 1000);
> +	else
> +		gain = (val * 1000) + (val2 / 1000);
> +
> +	if (gain > inf->gain_max || gain < inf->gain_min)
> +		return -EINVAL;
> +
> +	switch (st->type) {
> +	case ID_HMC425A:
> +		*code = ~((abs(gain) / 500) & 0x3F);

In the next patch I point out that this should be data or callbacks in in
the st->chip_info structure, not encoded in code here based on st->type (which
I want you to get rid of!)

> +		return 0;
> +	case ID_HMC540S:
> +		*code = ~((abs(gain) / 1000) & 0xF);
> +		return 0;
> +	case ID_ADRF5740:
> +		temp = (abs(gain) / 2000) & 0xF;
> +		*code = temp & BIT(3) ? temp | BIT(2) : temp;

Given you are moving the code, a comment here might be nice as it's unusual
(bits are 2DB, 4DB, 8DB and another 8DB)

> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int hmc425a_code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2)
> +{
> +	int code, gain;
> +
> +	code = st->gain;
> +	switch (st->type) {
> +	case ID_HMC425A:
> +		gain = ~code * -500;
> +		break;
> +	case ID_HMC540S:
> +		gain = ~code * -1000;
> +		break;
> +	case ID_ADRF5740:
> +		code = code & BIT(3) ? code & ~BIT(2) : code;
> +		gain = code * -2000;
> +		break;
> +	}
> +
> +	*val = gain / 1000;
> +	*val2 = (gain % 1000) * 1000;
> +
> +	return 0;
> +}
> +
>  static int hmc425a_read_raw(struct iio_dev *indio_dev,
>  			    struct iio_chan_spec const *chan, int *val,
>  			    int *val2, long m)
>  {
>  	struct hmc425a_state *st = iio_priv(indio_dev);
> -	int code, gain = 0;
>  	int ret;
>  
>  	mutex_lock(&st->lock);
>  	switch (m) {
>  	case IIO_CHAN_INFO_HARDWAREGAIN:
> -		code = st->gain;
> -
> -		switch (st->type) {
> -		case ID_HMC425A:
> -			gain = ~code * -500;
> -			break;
> -		case ID_HMC540S:
> -			gain = ~code * -1000;
> +		ret = hmc425a_code_to_gain_dB(st, val, val2);
> +		if (ret)
>  			break;
> -		case ID_ADRF5740:
> -			code = code & BIT(3) ? code & ~BIT(2) : code;
> -			gain = code * -2000;
> -			break;
> -		}
> -
> -		*val = gain / 1000;
> -		*val2 = (gain % 1000) * 1000;
> -
>  		ret = IIO_VAL_INT_PLUS_MICRO_DB;
>  		break;
>  	default:
> @@ -100,36 +137,15 @@ static int hmc425a_write_raw(struct iio_dev *indio_dev,
>  			     int val2, long mask)
>  {
>  	struct hmc425a_state *st = iio_priv(indio_dev);
> -	struct hmc425a_chip_info *inf = st->chip_info;
> -	int code = 0, gain;
> -	int ret;
> -
> -	if (val < 0)
> -		gain = (val * 1000) - (val2 / 1000);
> -	else
> -		gain = (val * 1000) + (val2 / 1000);
> -
> -	if (gain > inf->gain_max || gain < inf->gain_min)
> -		return -EINVAL;
> -
> -	switch (st->type) {
> -	case ID_HMC425A:
> -		code = ~((abs(gain) / 500) & 0x3F);
> -		break;
> -	case ID_HMC540S:
> -		code = ~((abs(gain) / 1000) & 0xF);
> -		break;
> -	case ID_ADRF5740:
> -		code = (abs(gain) / 2000) & 0xF;
> -		code = code & BIT(3) ? code | BIT(2) : code;
> -		break;
> -	}
> +	int code = 0, ret;
>  
>  	mutex_lock(&st->lock);
>  	switch (mask) {
>  	case IIO_CHAN_INFO_HARDWAREGAIN:
> +		ret = hmc425a_gain_dB_to_code(st, val, val2, &code);
> +		if (ret)
> +			break;
>  		st->gain = code;
> -
>  		ret = hmc425a_write(indio_dev, st->gain);
>  		break;
>  	default: