Re: [PATCH v4 4/7] power: supply: max8997_charger: Set CHARGER current limit

Timon Baetz
2020-12-24T13:14:04Z

On Thu, 24 Dec 2020 10:55:59 +0100, Krzysztof Kozlowski wrote:
> On Wed, Dec 23, 2020 at 01:43:05PM +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@protonmail.com>
> > ---
> > drivers/power/supply/max8997_charger.c | 89 ++++++++++++++++++++++++++
> > 1 file changed, 89 insertions(+)
> >
> > diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
> > index 1947af25879a..e8532e2af451 100644
> > --- a/drivers/power/supply/max8997_charger.c
> > +++ b/drivers/power/supply/max8997_charger.c
> > @@ -6,12 +6,14 @@
> > // MyungJoo Ham <myungjoo.ham@samsung.com>
> >
> > #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 +237,28 @@ static int max8997_battery_probe(struct platform_device *pdev)
> > return PTR_ERR(charger->battery);
> > }
> >
> > + charger->reg = devm_regulator_get(&pdev->dev, "charger");
>
> Since you do not use get_optional, you will always get a dummy
> regulator. In case of error, you should either print it or entirely fail
> the probe. Silently continuing makes it difficult to spot errors.
>
> Since the driver could operate in case of extcon/regulator error, just
> dev_err() so failure will be spotted with dmesg.

I will switch to devm_regulator_get_optional() and print an error on
failure, thanks.

> It will complain on older DTBs because you are introducing incompatible
> change, but that's expected. Just correct all other in-tree DTS.

The other 2 in-tree DTS don't have CHARGER regulators. Not sure
how to correct those. Should I add muic and charger nodes without a
charger-supply? It will still complain in that case.

Thanks for guiding me through this,
Timon

> > + charger->edev = extcon_get_edev_by_phandle(&pdev->dev, 0);
> > + if (PTR_ERR(charger->reg) == -EPROBE_DEFER ||
> > + PTR_ERR(charger->edev) == -EPROBE_DEFER)
> > + return -EPROBE_DEFER;
> > +
> > + if (!IS_ERR(charger->reg) && !IS_ERR(charger->edev)) {
> > + INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
> > + ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to add extcon evt stop action: %d\n", ret);
> > + return ret;
> > + }
> > + charger->extcon_nb.notifier_call = max8997_battery_extcon_evt;
> > + ret = devm_extcon_register_notifier_all(&pdev->dev, charger->edev,
> > + &charger->extcon_nb);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to register extcon notifier\n");
> > + return ret;
> > + };
> > + }
> > +
> > return 0;
> > }
> >
> > --
> > 2.25.1
> >
> >