linux-kernel - RE: [PATCH v2 3/3] power/supply: Add generic USB charger driver

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Message-Id: <1576493525.3.0@crapouillou.net>
Date:   Mon, 16 Dec 2019 11:52:05 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Peter Chen <peter.chen@....com>
Cc:     Sebastian Reichel <sre@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>, od@...c.me,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: RE: [PATCH v2 3/3] power/supply: Add generic USB charger driver

Hi Peter,


Le lun., déc. 16, 2019 at 01:24, Peter Chen <peter.chen@....com> a 
écrit :
> 
>>  >>  +
>>  >>  +	desc = &charger->desc;
>>  >>  +	desc->name = "usb-charger";
>>  >>  +	desc->properties = usb_charger_properties;
>>  >>  +	desc->num_properties = ARRAY_SIZE(usb_charger_properties);
>>  >>  +	desc->get_property = usb_charger_get_property;
>>  >>  +	desc->type = 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
>> 
>>  Well I don't really know. The USB role framework does not give any 
>> info about
>>  what's plugged.
>> 
> 
> What's the use case for this patch set? How it be used?

My devicetree:

usb_otg: usb@...40000 {
	compatible = "ingenic,jz4770-musb", "simple-mfd";
	reg = <0x13440000 0x10000>;
	[...]

	usb-role-switch;

	connector {
		compatible = "gpio-usb-b-connector", "usb-b-connector";
		label = "mini-USB";
		type = "mini";

		id-gpios = <&gpf 18 GPIO_ACTIVE_HIGH>;
		vbus-gpios = <&gpb 5 GPIO_ACTIVE_HIGH>;
		[...]
	};

	usb_charger: usb-charger {
		compatible = "usb-charger";
	};
};

The new gpio-usb-connector driver uses the ID/VBUS GPIOs to detect in 
which state (device, host, unconnected) a OTG connector is. However, 
that means I cannot use the standard gpio-charger driver to detect the 
presence of a charger based on the state of the VBUS gpio, since it's 
already requested here. So the point of this patchset is to provide an 
alternative to gpio-charger that works with OTG controllers compatible 
with 'usb-role-switch'.

Cheers,
-Paul


>>  >
>>  >>  +
>>  >>  +	charger->charger = 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 = 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[] = {
>>  >>  +	{ .compatible = "usb-charger" },
>>  >>  +	{ /* sentinel */ },
>>  >>  +};
>>  >>  +MODULE_DEVICE_TABLE(of, usb_charger_of_match);  +  +static 
>> struct
>>  >> platform_driver usb_charger_driver = {
>>  >>  +	.driver = {
>>  >>  +		.name = "usb-charger",
>>  >>  +		.of_match_table = of_match_ptr(usb_charger_of_match),
>>  >>  +	},
>>  >>  +	.probe = usb_charger_probe,
>>  >>  +};
>>  >>  +module_platform_driver(usb_charger_driver);
>>  >>  +
>>  >>  +MODULE_DESCRIPTION("Simple USB charger driver");
>>  >> +MODULE_AUTHOR("Paul Cercueil <paul@...pouillou.net>");
>>  >> +MODULE_LICENSE("GPL");
>>  >>  --
>>  >>  2.24.0
>>  >>
>>  >
>>  > --
>>  >
>>  > Thanks,
>>  > Peter Chen
>> 
>