Re: [PATCH v4 04/10] power: supply: max77693: Set charge current limits during init

[Krzysztof Kozlowski <krzk@kernel.org>]

On 16/08/2024 10:19, Artur Weber wrote:
> There are two charger current limit registers:
> 
> - Fast charge current limit (which controls current going from the
>   charger to the battery);
> - CHGIN input current limit (which controls current going into the
>   charger through the cable).
> 
> Add functions for setting both of the values, and set them to a
> safe default value of 500mA at initialization.
> 
> The value for the fast charge current limit can be modified by setting
> the constant-charge-current-max-ua DT property of the battery node
> specified in the monitored-battery charger DT property; the CHGIN input
> current limit will be set up later in the charger detection mechanism
> (in the future, the INPUT_CURRENT_LIMIT property could also be made
> writeable for userspace control of the current limit, while keeping
> the actual current limit from the charger to the battery intact
> so that users don't accidentally blow up their batteries with a bad
> value).
> 
> Acked-by: Lee Jones <lee@kernel.org>
> Tested-by: Henrik Grimler <henrik@grimler.se>
> Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
> ---
> Changes in v3:
> - Dropped CHARGER reg in favor of managing the registers directly
> 
> Changes in v2:
> - Squashed mfd include register additions into this commit
> - Changed from custom fast charge current property to monitored-battery
>   (devm_power_supply_register call has been moved up as it is needed by
>   the DT init function now)
> - Changed to adapt to both current limit values being managed by the
>   CHARGER regulator
> ---
>  drivers/power/supply/max77693_charger.c | 82 ++++++++++++++++++++++++++++-----
>  include/linux/mfd/max77693-private.h    |  2 +
>  2 files changed, 73 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/power/supply/max77693_charger.c b/drivers/power/supply/max77693_charger.c
> index 4caac142c428..17975ec69a6a 100644
> --- a/drivers/power/supply/max77693_charger.c
> +++ b/drivers/power/supply/max77693_charger.c
> @@ -26,6 +26,7 @@ struct max77693_charger {
>  	u32 min_system_volt;
>  	u32 thermal_regulation_temp;
>  	u32 batttery_overcurrent;
> +	u32 fast_charge_current;
>  	u32 charge_input_threshold_volt;
>  };
>  
> @@ -596,6 +597,48 @@ static int max77693_set_batttery_overcurrent(struct max77693_charger *chg,
>  			CHG_CNFG_12_B2SOVRC_MASK, data);
>  }
>  
> +static int max77693_set_input_current_limit(struct max77693_charger *chg,
> +		unsigned int uamp)
> +{
> +	unsigned int data;
> +
> +	if (uamp < 60000 || uamp > 2540000) {
> +		dev_err(chg->dev, "Wrong value for input current limit");
> +		return -EINVAL;
> +	};
> +
> +	data = uamp / 20000; /* 20mA steps */
> +
> +	data <<= CHG_CNFG_09_CHGIN_ILIM_SHIFT;
> +
> +	dev_dbg(chg->dev, "Input current limit: %u (0x%x)\n", uamp, data);
> +
> +	return regmap_update_bits(chg->max77693->regmap,
> +			MAX77693_CHG_REG_CHG_CNFG_09,
> +			CHG_CNFG_09_CHGIN_ILIM_MASK, data);
> +}
> +
> +static int max77693_set_fast_charge_current(struct max77693_charger *chg,
> +		unsigned int uamp)
> +{
> +	unsigned int data;
> +
> +	if (uamp > 2100000) {
> +		dev_err(chg->dev, "Wrong value for fast charge current\n");
> +		return -EINVAL;
> +	}
> +
> +	data = uamp / 33300; /* 0.1A/3 steps */
> +
> +	data <<= CHG_CNFG_02_CC_SHIFT;
> +
> +	dev_dbg(chg->dev, "Fast charge current: %u (0x%x)\n", uamp, data);
> +
> +	return regmap_update_bits(chg->max77693->regmap,
> +			MAX77693_CHG_REG_CHG_CNFG_02,
> +			CHG_CNFG_02_CC_MASK, data);
> +}
> +
>  static int max77693_set_charge_input_threshold_volt(struct max77693_charger *chg,
>  		unsigned int uvolt)
>  {
> @@ -673,6 +716,15 @@ static int max77693_reg_init(struct max77693_charger *chg)
>  	if (ret)
>  		return ret;
>  
> +	ret = max77693_set_fast_charge_current(chg, chg->fast_charge_current);
> +	if (ret)
> +		return ret;
> +
> +	ret = max77693_set_input_current_limit(chg,
> +				DEFAULT_FAST_CHARGE_CURRENT);
> +	if (ret)
> +		return ret;
> +
>  	return max77693_set_charge_input_threshold_volt(chg,
>  			chg->charge_input_threshold_volt);
>  }
> @@ -681,6 +733,7 @@ static int max77693_reg_init(struct max77693_charger *chg)
>  static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
>  {
>  	struct device_node *np = dev->of_node;
> +	struct power_supply_battery_info *battery_info;
>  
>  	if (!np) {
>  		dev_err(dev, "no charger OF node\n");
> @@ -708,11 +761,20 @@ static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
>  		chg->charge_input_threshold_volt =
>  			DEFAULT_CHARGER_INPUT_THRESHOLD_VOLT;
>  
> +	if (power_supply_get_battery_info(chg->charger, &battery_info) ||
> +			!battery_info->constant_charge_current_max_ua)
> +		chg->fast_charge_current = DEFAULT_FAST_CHARGE_CURRENT;
> +	else
> +		chg->fast_charge_current =
> +			battery_info->constant_charge_current_max_ua;
> +
>  	return 0;
>  }
>  #else /* CONFIG_OF */
>  static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
>  {
> +	chg->fast_charge_current = DEFAULT_FAST_CHARGE_CURRENT;
> +
>  	return 0;
>  }
>  #endif /* CONFIG_OF */
> @@ -732,6 +794,15 @@ static int max77693_charger_probe(struct platform_device *pdev)
>  	chg->dev = &pdev->dev;
>  	chg->max77693 = max77693;
>  
> +	psy_cfg.drv_data = chg;
> +
> +	chg->charger = devm_power_supply_register(&pdev->dev,
> +						  &max77693_charger_desc,
> +						  &psy_cfg);
> +	if (IS_ERR(chg->charger))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(chg->charger),
> +				     "failed: power supply register\n");

This code move is not explained in the commit msg. At least I could not
find it. Please explain why you need it in the commit msg.

BTW, if you are interested in devices using this driver, have time, in
general care about the code and want to respond to patches, feel free to
add yourself to driver's maintainer entry.



Best regards,
Krzysztof