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From:   Peter Chen <peter.chen@nxp.com>
To:     Paul Cercueil <paul@crapouillou.net>
CC:     Sebastian Reichel <sre@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "od@zcrc.me" <od@zcrc.me>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] power/supply: Add generic USB charger driver
Thread-Topic: [PATCH v2 3/3] power/supply: Add generic USB charger driver
Thread-Index: AQHVsDrKPWSbvY6T+0OJ94dLsbCA8qe2ObMA
Date:   Thu, 12 Dec 2019 09:18:17 +0000
Message-ID: <20191212091814.GA7035@b29397-desktop>
References: <20191211155032.167032-1-paul@crapouillou.net>
 <20191211155032.167032-3-paul@crapouillou.net>
In-Reply-To: <20191211155032.167032-3-paul@crapouillou.net>
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On 19-12-11 16:50:32, Paul Cercueil wrote:
> This simple charger driver uses the USB role switch framework to detect
> the presence of a charger. The USB charger will report as online when
> the USB role is set to device, and offline otherwise.
>=20
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>=20
> Notes:
>     v2: Instead of detecting charger state from USB PHY, we detect it fro=
m the
>         USB role in use.
>=20
>  drivers/power/supply/Kconfig               |   8 ++
>  drivers/power/supply/Makefile              |   1 +
>  drivers/power/supply/generic-usb-charger.c | 124 +++++++++++++++++++++
>  3 files changed, 133 insertions(+)
>  create mode 100644 drivers/power/supply/generic-usb-charger.c
>=20
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index 27164a1d3c7c..c4221bcabee4 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -51,6 +51,14 @@ config GENERIC_ADC_BATTERY
>  	  Say Y here to enable support for the generic battery driver
>  	  which uses IIO framework to read adc.
> =20
> +config GENERIC_USB_CHARGER
> +	tristate "Generic USB charger"
> +	depends on USB_SUPPORT
> +	select USB_ROLE_SWITCH
> +	help
> +	  Say Y here to enable a generic USB charger driver which uses
> +	  the USB role switch framework to detect the presence of the charger.
> +
>  config MAX8925_POWER
>  	tristate "MAX8925 battery charger support"
>  	depends on MFD_MAX8925
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefil=
e
> index 6c7da920ea83..03f9b553bdfc 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -8,6 +8,7 @@ power_supply-$(CONFIG_LEDS_TRIGGERS)	+=3D power_supply_le=
ds.o
>  obj-$(CONFIG_POWER_SUPPLY)	+=3D power_supply.o
>  obj-$(CONFIG_POWER_SUPPLY_HWMON) +=3D power_supply_hwmon.o
>  obj-$(CONFIG_GENERIC_ADC_BATTERY)	+=3D generic-adc-battery.o
> +obj-$(CONFIG_GENERIC_USB_CHARGER)	+=3D generic-usb-charger.o
> =20
>  obj-$(CONFIG_PDA_POWER)		+=3D pda_power.o
>  obj-$(CONFIG_APM_POWER)		+=3D apm_power.o
> diff --git a/drivers/power/supply/generic-usb-charger.c b/drivers/power/s=
upply/generic-usb-charger.c
> new file mode 100644
> index 000000000000..0493fafbd4c0
> --- /dev/null
> +++ b/drivers/power/supply/generic-usb-charger.c
> @@ -0,0 +1,124 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Simple USB charger driver
> + * Copyright (c) 2019 Paul Cercueil <paul@crapouillou.net>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/usb/role.h>
> +
> +struct usb_charger {
> +	struct notifier_block nb;
> +	struct usb_role_switch *role;
> +	struct power_supply_desc desc;
> +	struct power_supply *charger;
> +};
> +
> +static enum power_supply_property usb_charger_properties[] =3D {
> +	POWER_SUPPLY_PROP_ONLINE,
> +};
> +
> +static int usb_charger_get_property(struct power_supply *psy,
> +				    enum power_supply_property psp,
> +				    union power_supply_propval *val)
> +{
> +	struct usb_charger *charger =3D power_supply_get_drvdata(psy);
> +	enum usb_role role;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		role =3D usb_role_switch_get_role(charger->role);
> +		val->intval =3D role =3D=3D USB_ROLE_DEVICE;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int usb_charger_event(struct notifier_block *nb,
> +			     unsigned long event, void *d)
> +{
> +	struct usb_charger *charger =3D container_of(nb, struct usb_charger, nb=
);
> +
> +	power_supply_changed(charger->charger);
> +
> +	return 0;
> +}
> +
> +static void usb_charger_unregister(void *data)
> +{
> +	struct usb_charger *charger =3D data;
> +
> +	usb_role_switch_unregister_notifier(charger->role, &charger->nb);
> +}
> +
> +static int usb_charger_probe(struct platform_device *pdev)
> +{
> +	struct device *dev =3D &pdev->dev;
> +	struct power_supply_desc *desc;
> +	struct usb_charger *charger;
> +	struct power_supply_config cfg =3D {
> +		.of_node =3D dev->of_node,
> +	};
> +	int err;
> +
> +	charger =3D devm_kzalloc(dev, sizeof(*charger), GFP_KERNEL);
> +	if (!charger)
> +		return -ENOMEM;
> +
> +	cfg.drv_data =3D charger;
> +	charger->nb.notifier_call =3D usb_charger_event;
> +
> +	charger->role =3D usb_role_switch_get(dev);
> +	if (IS_ERR(charger->role)) {
> +		if (PTR_ERR(charger->role) !=3D -EPROBE_DEFER)
> +			dev_err(dev, "Unable to get USB role");
> +		return PTR_ERR(charger->role);
> +	}
> +
> +	desc =3D &charger->desc;
> +	desc->name =3D "usb-charger";
> +	desc->properties =3D usb_charger_properties;
> +	desc->num_properties =3D ARRAY_SIZE(usb_charger_properties);
> +	desc->get_property =3D usb_charger_get_property;
> +	desc->type =3D POWER_SUPPLY_TYPE_USB;

What's your further plan for this generic USB charger?
To support BC1.2, we need to know charger type, and how
we could get it?

Peter

> +
> +	charger->charger =3D devm_power_supply_register(dev, desc, &cfg);
> +	if (IS_ERR(charger->charger)) {
> +		dev_err(dev, "Unable to register charger");
> +		return PTR_ERR(charger->charger);
> +	}
> +
> +	err =3D usb_role_switch_register_notifier(charger->role, &charger->nb);
> +	if (err) {
> +		dev_err(dev, "Unable to register USB role switch notifier");
> +		return err;
> +	}
> +
> +	return devm_add_action_or_reset(dev, usb_charger_unregister, charger);
> +}
> +
> +static const struct of_device_id usb_charger_of_match[] =3D {
> +	{ .compatible =3D "usb-charger" },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, usb_charger_of_match);
> +
> +static struct platform_driver usb_charger_driver =3D {
> +	.driver =3D {
> +		.name =3D "usb-charger",
> +		.of_match_table =3D of_match_ptr(usb_charger_of_match),
> +	},
> +	.probe =3D usb_charger_probe,
> +};
> +module_platform_driver(usb_charger_driver);
> +
> +MODULE_DESCRIPTION("Simple USB charger driver");
> +MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
> +MODULE_LICENSE("GPL");
> --=20
> 2.24.0
>=20

--=20

Thanks,
Peter Chen=