Re: [PATCH v2 2/4] extcon: usb-gpio: add support for VBUS detection

[Robert Baldyga <r.baldyga@samsung.com>]

Hi Roger,

On 04/01/2015 01:28 PM, Roger Quadros wrote:
> Robert,
> 
> On 01/04/15 10:23, Robert Baldyga wrote:
>> This patch adds VBUS pin detection support to extcon-usb-gpio driver.
>> It allows to use this driver with boards which have both VBUS and ID
>> pins, or only one of them.
>>
>> Following table of states presents relationship between this signals
>> and detected cable type:
>>
>>  State              |    ID   |   VBUS
>> ----------------------------------------
>>  [1] USB            |    H    |    H
>>  [2] none           |    H    |    L
>>  [3] USB & USB-HOST |    L    |    H
>>  [4] USB-HOST       |    L    |    L
>>
>> In case we have only one of these signals:
>> - VBUS only - we want to distinguish between [1] and [2], so ID is always 1.
>> - ID only - we want to distinguish between [1] and [4], so VBUS = ID.
>>
>> Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
>> ---
>>  drivers/extcon/extcon-usb-gpio.c | 171 +++++++++++++++++++++++++++------------
>>  1 file changed, 119 insertions(+), 52 deletions(-)
>>
>> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
>> index f6aa99d..c842715 100644
>> --- a/drivers/extcon/extcon-usb-gpio.c
>> +++ b/drivers/extcon/extcon-usb-gpio.c
>> @@ -32,7 +32,9 @@ struct usb_extcon_info {
>>  	struct extcon_dev *edev;
>>  
>>  	struct gpio_desc *id_gpiod;
>> +	struct gpio_desc *vbus_gpiod;
>>  	int id_irq;
>> +	int vbus_irq;
>>  
>>  	unsigned long debounce_jiffies;
>>  	struct delayed_work wq_detcable;
>> @@ -52,40 +54,49 @@ static const char *usb_extcon_cable[] = {
>>  	NULL,
>>  };
>>  
>> +/*
>> + * "USB" = VBUS and "USB-HOST" = !ID, so we have:
>> + *
>> + *  State              |    ID   |   VBUS
>> + * ----------------------------------------
>> + *  [1] USB            |    H    |    H
>> + *  [2] none           |    H    |    L
>> + *  [3] USB & USB-HOST |    L    |    H
>> + *  [4] USB-HOST       |    L    |    L
>> + *
>> + * In case we have only one of these signals:
>> + * - VBUS only - we want to distinguish between [1] and [2], so ID is always 1.
>> + * - ID only - we want to distinguish between [1] and [4], so VBUS = ID.
>> + */
>> +
>>  static void usb_extcon_detect_cable(struct work_struct *work)
>>  {
>>  	int id;
>> +	int vbus;
>>  	struct usb_extcon_info *info = container_of(to_delayed_work(work),
>>  						    struct usb_extcon_info,
>>  						    wq_detcable);
>>  
>> -	/* check ID and update cable state */
>> -	id = gpiod_get_value_cansleep(info->id_gpiod);
>> -	if (id) {
>> -		/*
>> -		 * ID = 1 means USB HOST cable detached.
>> -		 * As we don't have event for USB peripheral cable attached,
>> -		 * we simulate USB peripheral attach here.
>> -		 */
>> -		extcon_set_cable_state(info->edev,
>> -				       usb_extcon_cable[EXTCON_CABLE_USB_HOST],
>> -				       false);
>> -		extcon_set_cable_state(info->edev,
>> -				       usb_extcon_cable[EXTCON_CABLE_USB],
>> -				       true);
>> -	} else {
>> -		/*
>> -		 * ID = 0 means USB HOST cable attached.
>> -		 * As we don't have event for USB peripheral cable detached,
>> -		 * we simulate USB peripheral detach here.
>> -		 */
>> +	/* check ID and VBUS and update cable state */
>> +
>> +	id = info->id_gpiod ?
>> +		gpiod_get_value_cansleep(info->id_gpiod) : 1;
>> +
>> +	vbus = info->vbus_gpiod ?
>> +		gpiod_get_value_cansleep(info->vbus_gpiod) : id;
>> +
>> +	/* at first we clean states which are no longer active */
>> +	if (id)
>>  		extcon_set_cable_state(info->edev,
>> -				       usb_extcon_cable[EXTCON_CABLE_USB],
>> -				       false);
>> +			usb_extcon_cable[EXTCON_CABLE_USB_HOST], false);
>> +	if (!vbus)
>>  		extcon_set_cable_state(info->edev,
>> -				       usb_extcon_cable[EXTCON_CABLE_USB_HOST],
>> -				       true);
>> -	}
>> +			usb_extcon_cable[EXTCON_CABLE_USB], false);
>> +
>> +	extcon_set_cable_state(info->edev,
>> +		usb_extcon_cable[EXTCON_CABLE_USB_HOST], !id);
>> +	extcon_set_cable_state(info->edev,
>> +		usb_extcon_cable[EXTCON_CABLE_USB], vbus);
> 
> This approach has the following problems:
> 1) If ID is 1 then extcon_set_cable_state(USB_HOST, false) gets called twice.
> 2) If VBUS is 0 then extcon_set_cable_state(USB, false) gets called twice.
> 3) When both ID and VBUS are available, even if either one changes state then we unnecessarily
> update the other pins cable state as well.
> 
> This is probably not an issue as extcon core might be ignoring duplicate set_cable_states,
> but I think we should avoid them if we can. I wouldn't mind (3) as we unnecessarily need to
> keep track of previous states, but (1) and (2) should be fixed.
> 

Extcon core is responsible for storing current cable state to let us do
not worry about that. However if we really do want to get rid of
redundant usb_extcon_cable() calls, we can create separate interrupt
handler for VBUS.

Br,
Robert Baldyga

> 
>>  }
>>  
>>  static irqreturn_t usb_irq_handler(int irq, void *dev_id)
>> @@ -113,10 +124,12 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>  		return -ENOMEM;
>>  
>>  	info->dev = dev;
>> -	info->id_gpiod = devm_gpiod_get(&pdev->dev, "id");
>> -	if (IS_ERR(info->id_gpiod)) {
>> -		dev_err(dev, "failed to get ID GPIO\n");
>> -		return PTR_ERR(info->id_gpiod);
>> +	info->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id");
>> +	info->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus");
>> +
>> +	if (!info->id_gpiod && !info->vbus_gpiod) {
>> +		dev_err(dev, "failed to get gpios\n");
>> +		return -ENODEV;
>>  	}
>>  
>>  	info->edev = devm_extcon_dev_allocate(dev, usb_extcon_cable);
>> @@ -131,27 +144,51 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>  		return ret;
>>  	}
>>  
>> -	ret = gpiod_set_debounce(info->id_gpiod,
>> -				 USB_GPIO_DEBOUNCE_MS * 1000);
>> +	if (info->id_gpiod)
>> +		ret = gpiod_set_debounce(info->id_gpiod,
>> +			USB_GPIO_DEBOUNCE_MS * 1000);
>> +	if (!ret && info->vbus_gpiod) {
>> +		ret = gpiod_set_debounce(info->vbus_gpiod,
>> +			USB_GPIO_DEBOUNCE_MS * 1000);
>> +		if (ret < 0 && info->id_gpiod)
>> +			gpiod_set_debounce(info->vbus_gpiod, 0);
>> +	}
>>  	if (ret < 0)
>>  		info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
>>  
>>  	INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
>>  
>> -	info->id_irq = gpiod_to_irq(info->id_gpiod);
>> -	if (info->id_irq < 0) {
>> -		dev_err(dev, "failed to get ID IRQ\n");
>> -		return info->id_irq;
>> +	if (info->id_gpiod) {
>> +		info->id_irq = gpiod_to_irq(info->id_gpiod);
>> +		if (info->id_irq < 0) {
>> +			dev_err(dev, "failed to get ID IRQ\n");
>> +			return info->id_irq;
>> +		}
>> +		ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
>> +				usb_irq_handler,
>> +				IRQF_TRIGGER_RISING |
>> +				IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>> +				pdev->name, info);
>> +		if (ret < 0) {
>> +			dev_err(dev, "failed to request handler for ID IRQ\n");
>> +			return ret;
>> +		}
>>  	}
>> -
>> -	ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
>> -					usb_irq_handler,
>> -					IRQF_TRIGGER_RISING |
>> -					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>> -					pdev->name, info);
>> -	if (ret < 0) {
>> -		dev_err(dev, "failed to request handler for ID IRQ\n");
>> -		return ret;
>> +	if (info->vbus_gpiod) {
>> +		info->vbus_irq = gpiod_to_irq(info->vbus_gpiod);
>> +		if (info->vbus_irq < 0) {
>> +			dev_err(dev, "failed to get VBUS IRQ\n");
>> +			return info->vbus_irq;
>> +		}
>> +		ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
>> +				usb_irq_handler,
>> +				IRQF_TRIGGER_RISING |
>> +				IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>> +				pdev->name, info);
>> +		if (ret < 0) {
>> +			dev_err(dev, "failed to request handler for VBUS IRQ\n");
>> +			return ret;
>> +		}
>>  	}
>>  
>>  	platform_set_drvdata(pdev, info);
>> @@ -179,9 +216,16 @@ static int usb_extcon_suspend(struct device *dev)
>>  	int ret = 0;
>>  
>>  	if (device_may_wakeup(dev)) {
>> -		ret = enable_irq_wake(info->id_irq);
>> -		if (ret)
>> -			return ret;
>> +		if (info->id_gpiod) {
>> +			ret = enable_irq_wake(info->id_irq);
>> +			if (ret)
>> +				return ret;
>> +		}
>> +		if (info->vbus_gpiod) {
>> +			ret = enable_irq_wake(info->vbus_irq);
>> +			if (ret)
>> +				goto err;
>> +		}
>>  	}
>>  
>>  	/*
>> @@ -189,8 +233,16 @@ static int usb_extcon_suspend(struct device *dev)
>>  	 * as GPIOs used behind I2C subsystem might not be
>>  	 * accessible until resume completes. So disable IRQ.
>>  	 */
>> -	disable_irq(info->id_irq);
>> +	if (info->id_gpiod)
>> +		disable_irq(info->id_irq);
>> +	if (info->vbus_gpiod)
>> +		disable_irq(info->vbus_irq);
>> +
>> +	return ret;
>>  
>> +err:
>> +	if (info->id_gpiod)
>> +		disable_irq_wake(info->id_irq);
>>  	return ret;
>>  }
>>  
>> @@ -200,13 +252,28 @@ static int usb_extcon_resume(struct device *dev)
>>  	int ret = 0;
>>  
>>  	if (device_may_wakeup(dev)) {
>> -		ret = disable_irq_wake(info->id_irq);
>> -		if (ret)
>> -			return ret;
>> +		if (info->id_gpiod) {
>> +			ret = disable_irq_wake(info->id_irq);
>> +			if (ret)
>> +				return ret;
>> +		}
>> +		if (info->vbus_gpiod) {
>> +			ret = disable_irq_wake(info->vbus_irq);
>> +			if (ret)
>> +				goto err;
>> +		}
>>  	}
>>  
>> -	enable_irq(info->id_irq);
>> +	if (info->id_gpiod)
>> +		enable_irq(info->id_irq);
>> +	if (info->vbus_gpiod)
>> +		enable_irq(info->vbus_irq);
>> +
>> +	return ret;
>>  
>> +err:
>> +	if (info->id_gpiod)
>> +		enable_irq_wake(info->id_irq);
>>  	return ret;
>>  }
>>  #endif
>>
> 
>