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

Paul Cercueil <paul@xxxxxxxxxxxxxxx> · Mon, 27 Jul 2020 17:02:59 +0200

Le lun. 27 juil. 2020 à 13:42, Chunfeng Yun 
<chunfeng.yun@xxxxxxxxxxxx> 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@xxxxxxxxx> a écrit :
 > 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.

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