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

[Paul Cercueil <paul@crapouillou.net>]

Le lun. 27 juil. 2020 à 13:42, Chunfeng Yun 
<chunfeng.yun@mediatek.com> a écrit :
> On Sun, 2020-07-26 at 12:27 +0200, Paul Cercueil wrote:
>> 
>>  Le dim. 26 juil. 2020 à 13:14, Andy Shevchenko
>>  <andy.shevchenko@gmail.com> a écrit :
>>  > On Mon, Jun 22, 2020 at 1:51 AM Paul Cercueil 
>> <paul@crapouillou.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?
>> 
>>  We can't have extcon and USB role detection at the same time.
>> 
>>  -Paul
>> 
>>  >>  Signed-off-by: Paul Cercueil <paul@crapouillou.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;
> 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.

If you read carefully, info->last_role is not modified here :)

-Paul

> 
>>  >>  +               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
>> 
>> 
>