linux-kernel - Re: [PATCH v2 15/17] power: axp20x_battery: Add constant charge current table

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Message-ID: <20220609211128.5knoptfwhongwrtq@mercury.elektranox.org>
Date:   Thu, 9 Jun 2022 23:11:28 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Aidan MacDonald <aidanmacdonald.0x0@...il.com>
Cc:     linus.walleij@...aro.org, brgl@...ev.pl, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, wens@...e.org, jic23@...nel.org,
        lee.jones@...aro.org, broonie@...nel.org,
        gregkh@...uxfoundation.org, lgirdwood@...il.com, lars@...afoo.de,
        rafael@...nel.org, quic_gurus@...cinc.com,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 15/17] power: axp20x_battery: Add constant charge
 current table

Hi,

On Tue, Jun 07, 2022 at 04:53:22PM +0100, Aidan MacDonald wrote:
> Add a table-based lookup method for constant charge current,
> which is necessary when the setting cannot be represented as
> a linear range.
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@...il.com>
> ---
>  drivers/power/supply/axp20x_battery.c | 53 +++++++++++++++++++++------
>  1 file changed, 41 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/power/supply/axp20x_battery.c b/drivers/power/supply/axp20x_battery.c
> index 9106077c0dbb..87fb958f2224 100644
> --- a/drivers/power/supply/axp20x_battery.c
> +++ b/drivers/power/supply/axp20x_battery.c
> @@ -61,6 +61,7 @@ struct axp20x_batt_ps;
>  struct axp_data {
>  	int	ccc_scale;
>  	int	ccc_offset;
> +	const int *ccc_table;

Please document the struct; especially the fact that ccc_table must
have a size of AXP20X_CHRG_CTRL1_TGT_CURR + 1.

-- Sebastian

>  	bool	has_fg_valid;
>  	int	(*get_max_voltage)(struct axp20x_batt_ps *batt, int *val);
>  	int	(*set_max_voltage)(struct axp20x_batt_ps *batt, int val);
> @@ -176,7 +177,10 @@ static int axp20x_get_constant_charge_current(struct axp20x_batt_ps *axp,
>  
>  	*val &= AXP20X_CHRG_CTRL1_TGT_CURR;
>  
> -	*val = *val * axp->data->ccc_scale + axp->data->ccc_offset;
> +	if (axp->data->ccc_table)
> +		*val = axp->data->ccc_table[*val];
> +	else
> +		*val = *val * axp->data->ccc_scale + axp->data->ccc_offset;
>  
>  	return 0;
>  }
> @@ -389,16 +393,36 @@ static int axp20x_battery_set_max_voltage(struct axp20x_batt_ps *axp20x_batt,
>  				  AXP20X_CHRG_CTRL1_TGT_VOLT, val);
>  }
>  
> +static int axp20x_get_constant_charge_current_sel(struct axp20x_batt_ps *axp_batt,
> +						  int charge_current)
> +{
> +	int i;
> +
> +	if (axp_batt->data->ccc_table) {
> +		for (i = AXP20X_CHRG_CTRL1_TGT_CURR; i >= 0; --i) {
> +			if (axp_batt->data->ccc_table[i] <= charge_current)
> +				return i;
> +		}
> +
> +		return -EINVAL;
> +	}
> +
> +	i = (charge_current - axp_batt->data->ccc_offset) / axp_batt->data->ccc_scale;
> +
> +	if (i > AXP20X_CHRG_CTRL1_TGT_CURR || i < 0)
> +		return -EINVAL;
> +
> +	return i;
> +}
> +
>  static int axp20x_set_constant_charge_current(struct axp20x_batt_ps *axp_batt,
>  					      int charge_current)
>  {
>  	if (charge_current > axp_batt->max_ccc)
>  		return -EINVAL;
>  
> -	charge_current = (charge_current - axp_batt->data->ccc_offset) /
> -		axp_batt->data->ccc_scale;
> -
> -	if (charge_current > AXP20X_CHRG_CTRL1_TGT_CURR || charge_current < 0)
> +	charge_current = axp20x_get_constant_charge_current_sel(axp_batt, charge_current);
> +	if (charge_current < 0)
>  		return -EINVAL;
>  
>  	return regmap_update_bits(axp_batt->regmap, AXP20X_CHRG_CTRL1,
> @@ -410,14 +434,14 @@ static int axp20x_set_max_constant_charge_current(struct axp20x_batt_ps *axp,
>  {
>  	bool lower_max = false;
>  
> -	charge_current = (charge_current - axp->data->ccc_offset) /
> -		axp->data->ccc_scale;
> -
> -	if (charge_current > AXP20X_CHRG_CTRL1_TGT_CURR || charge_current < 0)
> +	charge_current = axp20x_get_constant_charge_current_sel(axp, charge_current);
> +	if (charge_current < 0)
>  		return -EINVAL;
>  
> -	charge_current = charge_current * axp->data->ccc_scale +
> -		axp->data->ccc_offset;
> +	if (axp->data->ccc_table)
> +		charge_current = axp->data->ccc_table[charge_current];
> +	else
> +		charge_current = charge_current * axp->data->ccc_scale + axp->data->ccc_offset;
>  
>  	if (charge_current > axp->max_ccc)
>  		dev_warn(axp->dev,
> @@ -629,7 +653,12 @@ static int axp20x_power_probe(struct platform_device *pdev)
>  								   ccc)) {
>  			dev_err(&pdev->dev,
>  				"couldn't set constant charge current from DT: fallback to minimum value\n");
> -			ccc = 300000;
> +
> +			if (axp20x_batt->data->ccc_table)
> +				ccc = axp20x_batt->data->ccc_table[0];
> +			else
> +				ccc = axp20x_batt->data->ccc_offset;
> +
>  			axp20x_batt->max_ccc = ccc;
>  			axp20x_set_constant_charge_current(axp20x_batt, ccc);
>  		}
> -- 
> 2.35.1
> 

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