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

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Message-Id: <1576617863.3.1@crapouillou.net>
Date:   Tue, 17 Dec 2019 22:24:23 +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 mar., déc. 17, 2019 at 01:32, Peter Chen <peter.chen@....com> a 
écrit :
> 
>>  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'.
>> 
> 
> Thanks for explaining it.
> 
> What's the user for this USB charger,  PMIC or what else? How the 
> user uses
> this USB charger interface?

It's exported as a standard charger, so it can be passed to client 
drivers through devicetree, and its online status can be retrieved from 
sysfs.

-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
>>  >>
>>  >
>> 
>