Re: [PATCH v2 3/3] power/supply: Add generic USB charger driver

[Peter Chen]

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.
> 
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> ---
> 
> Notes:
>     v2: Instead of detecting charger state from USB PHY, we detect it from the
>         USB role in use.
> 
>  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
> 
> 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.
>  
> +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/Makefile
> index 6c7da920ea83..03f9b553bdfc 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -8,6 +8,7 @@ power_supply-$(CONFIG_LEDS_TRIGGERS)	+= power_supply_leds.o
>  obj-$(CONFIG_POWER_SUPPLY)	+= power_supply.o
>  obj-$(CONFIG_POWER_SUPPLY_HWMON) += power_supply_hwmon.o
>  obj-$(CONFIG_GENERIC_ADC_BATTERY)	+= generic-adc-battery.o
> +obj-$(CONFIG_GENERIC_USB_CHARGER)	+= generic-usb-charger.o
>  
>  obj-$(CONFIG_PDA_POWER)		+= pda_power.o
>  obj-$(CONFIG_APM_POWER)		+= apm_power.o
> diff --git a/drivers/power/supply/generic-usb-charger.c b/drivers/power/supply/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@xxxxxxxxxxxxxxx>
> + */
> +
> +#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[] = {
> +	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 = power_supply_get_drvdata(psy);
> +	enum usb_role role;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		role = usb_role_switch_get_role(charger->role);
> +		val->intval = role == 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 = 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 = data;
> +
> +	usb_role_switch_unregister_notifier(charger->role, &charger->nb);
> +}
> +
> +static int usb_charger_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct power_supply_desc *desc;
> +	struct usb_charger *charger;
> +	struct power_supply_config cfg = {
> +		.of_node = dev->of_node,
> +	};
> +	int err;
> +
> +	charger = devm_kzalloc(dev, sizeof(*charger), GFP_KERNEL);
> +	if (!charger)
> +		return -ENOMEM;
> +
> +	cfg.drv_data = charger;
> +	charger->nb.notifier_call = usb_charger_event;
> +
> +	charger->role = usb_role_switch_get(dev);
> +	if (IS_ERR(charger->role)) {
> +		if (PTR_ERR(charger->role) != -EPROBE_DEFER)
> +			dev_err(dev, "Unable to get USB role");
> +		return PTR_ERR(charger->role);
> +	}
> +
> +	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

> +
> +	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@xxxxxxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> -- 
> 2.24.0
> 

-- 

Thanks,
Peter Chen