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

[Chunfeng Yun]

On Sun, 2020-07-26 at 12:27 +0200, Paul Cercueil wrote:
> 
> Le dim. 26 juil. 2020 Ã 13:14, Andy Shevchenko 
> <andy.shevchenko@xxxxxxxxx> a Ãcrit :
> > On Mon, Jun 22, 2020 at 1:51 AM Paul Cercueil <paul@xxxxxxxxxxxxxxx> 
> > 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?
> 
> We can't have extcon and USB role detection at the same time.
> 
> -Paul
> 
> >>  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >>  ---
> >>   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;
What will happen if you not change info->last_role here?
I prefer it's only changed by usb_conn_isr(), if it's changed by other
drivers, for example, through power_supply_get_property(), may skip role
switch.

> >>  +               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
> 
>