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

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Date:   Fri, 10 Jun 2022 16:40:42 +0100
From:   Aidan MacDonald <aidanmacdonald.0x0@...il.com>
To:     Sebastian Reichel <sebastian.reichel@...labora.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


Sebastian Reichel <sebastian.reichel@...labora.com> writes:

> 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
>

Thanks, I'll make sure to do that in v3.

Regards,
Aidan

>>  	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
>>