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

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Message-ID: <CAHp75VcfhDncqP_hSVvRNc_vY0fOYaoxm-tiCm2G92Xrisb9hA@mail.gmail.com>
Date:   Sun, 26 Jul 2020 13:14:15 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Paul Cercueil <paul@...pouillou.net>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>, od@...c.me,
        USB <linux-usb@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH] usb: common: usb-conn-gpio: Register optional charger

On Mon, Jun 22, 2020 at 1:51 AM Paul Cercueil <paul@...pouillou.net> wrote:
>
> 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.

I'm not sure I understand the purpose of this (third?) way to detect
USB charger and notify user space about.
Why is extcon not good enough?

> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>  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 */
> --
> 2.27.0
>


-- 
With Best Regards,
Andy Shevchenko