linux-kernel - Re: [PATCH] usb: common: usb-conn-gpio: Register optional charger

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Message-Id: <9KB7BQ.BH9P6TT11PEH2@crapouillou.net>
Date:   Sun, 31 May 2020 17:12:09 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Chunfeng Yun <chunfeng.yun@...iatek.com>, od@...c.me,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: common: usb-conn-gpio: Register optional charger

Hi,

Any feedback on this patch?

Cheers,
-Paul


Le lun. 13 avril 2020 à 14:25, Paul Cercueil <paul@...pouillou.net> a 
écrit :
> Register a power supply charger, if the Kconfig option
> USB_CONN_GPIO_CHARGER is set, whose online state depends on whether
> the USB role is set to device or not.
> 
> This is useful when the USB role is the only way to know if the device
> is charging from USB. The API is the standard power supply charger 
> API,
> you get a /sys/class/power_supply/xxx/online node which tells you the
> state of the charger.
> 
> The sole purpose of this is to give userspace applications a way to
> know whether or not the charger is plugged.
> 
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
> 
> Notes:
>     v2: - improve commit message... explain why we want a charger
>         - compile charger code only if CONFIG_USB_CONN_GPIO_CHARGER
>     	  is set
> 
>  drivers/usb/common/Kconfig         | 11 +++++++
>  drivers/usb/common/usb-conn-gpio.c | 47 
> ++++++++++++++++++++++++++++++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/drivers/usb/common/Kconfig b/drivers/usb/common/Kconfig
> index d611477aae41..5405ae96c68f 100644
> --- a/drivers/usb/common/Kconfig
> +++ b/drivers/usb/common/Kconfig
> @@ -49,3 +49,14 @@ config USB_CONN_GPIO
> 
>  	  To compile the driver as a module, choose M here: the module will
>  	  be called usb-conn-gpio.ko
> +
> +if USB_CONN_GPIO
> +
> +config USB_CONN_GPIO_CHARGER
> +	bool "USB charger support"
> +	select POWER_SUPPLY
> +	help
> +	  Register a charger with the power supply subsystem. This will 
> allow
> +	  userspace to know whether or not the device is charging from USB.
> +
> +endif
> diff --git a/drivers/usb/common/usb-conn-gpio.c 
> b/drivers/usb/common/usb-conn-gpio.c
> index ed204cbb63ea..129d48db280b 100644
> --- a/drivers/usb/common/usb-conn-gpio.c
> +++ b/drivers/usb/common/usb-conn-gpio.c
> @@ -17,6 +17,7 @@
>  #include <linux/of.h>
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
> +#include <linux/power_supply.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/usb/role.h>
> 
> @@ -38,6 +39,9 @@ struct usb_conn_info {
>  	struct gpio_desc *vbus_gpiod;
>  	int id_irq;
>  	int vbus_irq;
> +
> +	struct power_supply_desc desc;
> +	struct power_supply *charger;
>  };
> 
>  /**
> @@ -98,6 +102,8 @@ static void usb_conn_detect_cable(struct 
> work_struct *work)
>  		ret = regulator_enable(info->vbus);
>  		if (ret)
>  			dev_err(info->dev, "enable vbus regulator failed\n");
> +	} else if (IS_ENABLED(CONFIG_USB_CONN_GPIO_CHARGER)) {
> +		power_supply_changed(info->charger);
>  	}
> 
>  	info->last_role = role;
> @@ -121,10 +127,35 @@ static irqreturn_t usb_conn_isr(int irq, void 
> *dev_id)
>  	return IRQ_HANDLED;
>  }
> 
> +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_conn_info *info = power_supply_get_drvdata(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		val->intval = info->last_role == USB_ROLE_DEVICE;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static int usb_conn_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> +	struct power_supply_desc *desc;
>  	struct usb_conn_info *info;
> +	struct power_supply_config cfg = {
> +		.of_node = dev->of_node,
> +	};
>  	int ret = 0;
> 
>  	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> @@ -203,6 +234,22 @@ static int usb_conn_probe(struct platform_device 
> *pdev)
>  		}
>  	}
> 
> +	if (IS_ENABLED(CONFIG_USB_CONN_GPIO_CHARGER)) {
> +		desc = &info->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;
> +		cfg.drv_data = info;
> +
> +		info->charger = devm_power_supply_register(dev, desc, &cfg);
> +		if (IS_ERR(info->charger)) {
> +			dev_err(dev, "Unable to register charger\n");
> +			return PTR_ERR(info->charger);
> +		}
> +	}
> +
>  	platform_set_drvdata(pdev, info);
> 
>  	/* Perform initial detection */
> --
> 2.25.1
>