Re: [PATCH v3 4/7] power: supply: max8997_charger: Set CHARGER current limit

[Timon Baetz]

On Tue, 22 Dec 2020 09:40:04 +0100, Krzysztof Kozlowski wrote:
> On Tue, Dec 22, 2020 at 07:31:40AM +0000, Timon Baetz wrote:
> > Register for extcon notification and set charging current depending on
> > the detected cable type. Current values are taken from vendor kernel,
> > where most charger types end up setting 650mA [0].
> >
> > Also enable and disable the CHARGER regulator based on extcon events.
> >
> > [0] https://github.com/krzk/linux-vendor-backup/blob/samsung/galaxy-s2-epic-4g-touch-sph-d710-exynos4210-dump/drivers/misc/max8997-muic.c#L1675-L1678
> >
> > Signed-off-by: Timon Baetz <timon.baetz@xxxxxxxxxxxxxx>
> > ---
> >  drivers/power/supply/max8997_charger.c | 94 ++++++++++++++++++++++++++
> >  1 file changed, 94 insertions(+)
> >
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> > index 1947af25879a..673ffff14ae0 100644
> > --- a/drivers/power/supply/max8997_charger.c
> > +++ b/drivers/power/supply/max8997_charger.c
> > @@ -6,12 +6,14 @@
> >  //  MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> >
> >  #include <linux/err.h>
> > +#include <linux/extcon.h>
> >  #include <linux/module.h>
> >  #include <linux/slab.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/power_supply.h>
> >  #include <linux/mfd/max8997.h>
> >  #include <linux/mfd/max8997-private.h>
> > +#include <linux/regulator/consumer.h>
> >
> >  /* MAX8997_REG_STATUS4 */
> >  #define DCINOK_SHIFT		1
> > @@ -31,6 +33,10 @@ struct charger_data {
> >  	struct device *dev;
> >  	struct max8997_dev *iodev;
> >  	struct power_supply *battery;
> > +	struct regulator *reg;
> > +	struct extcon_dev *edev;
> > +	struct notifier_block extcon_nb;
> > +	struct work_struct extcon_work;
> >  };
> >
> >  static enum power_supply_property max8997_battery_props[] = {
> > @@ -88,6 +94,67 @@ static int max8997_battery_get_property(struct power_supply *psy,
> >  	return 0;
> >  }
> >
> > +static void max8997_battery_extcon_evt_stop_work(void *data)
> > +{
> > +	struct charger_data *charger = data;
> > +
> > +	cancel_work_sync(&charger->extcon_work);
> > +}
> > +
> > +static void max8997_battery_extcon_evt_worker(struct work_struct *work)
> > +{
> > +	struct charger_data *charger =
> > +	    container_of(work, struct charger_data, extcon_work);
> > +	struct extcon_dev *edev = charger->edev;
> > +	int current_limit;
> > +
> > +	if (extcon_get_state(edev, EXTCON_CHG_USB_SDP) > 0) {
> > +		dev_dbg(charger->dev, "USB SDP charger is connected\n");
> > +		current_limit = 450000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_DCP) > 0) {
> > +		dev_dbg(charger->dev, "USB DCP charger is connected\n");
> > +		current_limit = 650000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_FAST) > 0) {
> > +		dev_dbg(charger->dev, "USB FAST charger is connected\n");
> > +		current_limit = 650000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_SLOW) > 0) {
> > +		dev_dbg(charger->dev, "USB SLOW charger is connected\n");
> > +		current_limit = 650000;
> > +	} else if (extcon_get_state(edev, EXTCON_CHG_USB_CDP) > 0) {
> > +		dev_dbg(charger->dev, "USB CDP charger is connected\n");
> > +		current_limit = 650000;
> > +	} else {
> > +		dev_dbg(charger->dev, "USB charger is diconnected\n");
> > +		current_limit = -1;
> > +	}
> > +
> > +	if (current_limit > 0) {
> > +		int ret = regulator_set_current_limit(charger->reg, current_limit, current_limit);
> > +
> > +		if (ret) {
> > +			dev_err(charger->dev, "failed to set current limit: %d\n", ret);
> > +			return;
> > +		}
> > +		ret = regulator_enable(charger->reg);
> > +		if (ret)
> > +			dev_err(charger->dev, "failed to enable regulator: %d\n", ret);
> > +	} else {
> > +		int ret  = regulator_disable(charger->reg);
> > +
> > +		if (ret)
> > +			dev_err(charger->dev, "failed to disable regulator: %d\n", ret);
> > +	}
> > +}
> > +
> > +static int max8997_battery_extcon_evt(struct notifier_block *nb,
> > +				unsigned long event, void *param)
> > +{
> > +	struct charger_data *charger =
> > +		container_of(nb, struct charger_data, extcon_nb);
> > +	schedule_work(&charger->extcon_work);
> > +	return NOTIFY_OK;
> > +}
> > +
> >  static const struct power_supply_desc max8997_battery_desc = {
> >  	.name		= "max8997_pmic",
> >  	.type		= POWER_SUPPLY_TYPE_BATTERY,
> > @@ -170,6 +237,33 @@ static int max8997_battery_probe(struct platform_device *pdev)
> >  		return PTR_ERR(charger->battery);
> >  	}
> >
> > +	charger->reg = devm_regulator_get(&pdev->dev, "charger");  
> 
> The code looks good but isn't it breaking all existing platforms?

So there is 2 other DTS in the kernel sources that are using MAX8997
pmic:
 - Insignal Origen evaluation board
 - Samsung Trats
Non of them have charging regulators.
Also probing of the charger has been failing for long time because of 
https://lore.kernel.org/lkml/20201109194251.562203-2-timon.baetz@xxxxxxxxxxxxxx/
but that seems to land in 5.11.

That being said, I guess I could make extcon and charger-supply
optional if you prefer.

Thanks again for reviewing,
Timon