Re: [PATCH 7/8] usb: misc: eud: Handle usb role switch notifications

[Elson Serrao]

On 7/31/2024 6:06 AM, Dmitry Baryshkov wrote:
> On Tue, Jul 30, 2024 at 03:24:38PM GMT, Elson Roy Serrao wrote:
>> Since EUD is physically present between the USB connector and
>> the USB controller, it should relay the usb role notifications
>> from the connector. Hence register a role switch handler to
>> process and relay these roles to the USB controller. This results
>> in a common framework to send both connector related events
>> and eud attach/detach events to the USB controller.
>>
>> Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
>> ---
>>  drivers/usb/misc/qcom_eud.c | 91 ++++++++++++++++++++++++++++---------
>>  1 file changed, 69 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
>> index 3de7d465912c..9a49c934e8cf 100644
>> --- a/drivers/usb/misc/qcom_eud.c
>> +++ b/drivers/usb/misc/qcom_eud.c
>> @@ -10,6 +10,7 @@
>>  #include <linux/iopoll.h>
>>  #include <linux/kernel.h>
>>  #include <linux/module.h>
>> +#include <linux/mutex.h>
>>  #include <linux/of.h>
>>  #include <linux/phy/phy.h>
>>  #include <linux/platform_device.h>
>> @@ -35,12 +36,16 @@ struct eud_chip {
>>  	struct device			*dev;
>>  	struct usb_role_switch		*role_sw;
>>  	struct phy			*usb2_phy;
>> +
>> +	/* mode lock */
>> +	struct mutex			mutex;
>>  	void __iomem			*base;
>>  	void __iomem			*mode_mgr;
>>  	unsigned int			int_status;
>>  	int				irq;
>>  	bool				enabled;
>>  	bool				usb_attached;
>> +	enum usb_role			current_role;
>>  };
>>  
>>  static int eud_phy_enable(struct eud_chip *chip)
>> @@ -64,6 +69,38 @@ static void eud_phy_disable(struct eud_chip *chip)
>>  	phy_exit(chip->usb2_phy);
>>  }
>>  
>> +static int eud_usb_role_set(struct eud_chip *chip, enum usb_role role)
>> +{
>> +	struct usb_role_switch *sw;
>> +	int ret = 0;
>> +
>> +	mutex_lock(&chip->mutex);
>> +
>> +	/* Avoid duplicate role handling */
>> +	if (role == chip->current_role)
>> +		goto err;
>> +
>> +	sw = usb_role_switch_get(chip->dev);
> 
> Why isn't chip->role_sw good enough? Why do you need to get it each
> time?
>

Hi Dmitry

chip->role_sw is the eud role switch handler to receive role switch notifications from the
USB connector. The 'sw' I am getting above is the role switch handler of the USB controller.
As per this design, EUD receives role switch notification from the connector 
(via chip->role_sw) and then relays it to the 'sw' switch handler of the USB controller.


Thanks
Elson
 
>> +	if (IS_ERR_OR_NULL(sw)) {
>> +		dev_err(chip->dev, "failed to get usb switch\n");
>> +		ret = -EINVAL;
>> +		goto err;
>> +	}
>> +
>> +	ret = usb_role_switch_set_role(sw, role);
>> +	usb_role_switch_put(sw);
>> +
>> +	if (ret) {
>> +		dev_err(chip->dev, "failed to set role\n");
>> +		goto err;
>> +	}
>> +	chip->current_role = role;
>> +err:
>> +	mutex_unlock(&chip->mutex);
>> +
>> +	return ret;
>> +}
>> +
>>  static int enable_eud(struct eud_chip *priv)
>>  {
>>  	int ret;
>> @@ -77,7 +114,7 @@ static int enable_eud(struct eud_chip *priv)
>>  			priv->base + EUD_REG_INT1_EN_MASK);
>>  	writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
>>  
>> -	return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
>> +	return ret;
>>  }
>>  
>>  static void disable_eud(struct eud_chip *priv)
>> @@ -106,15 +143,20 @@ static ssize_t enable_store(struct device *dev,
>>  	if (kstrtobool(buf, &enable))
>>  		return -EINVAL;
>>  
>> +	/* EUD enable is applicable only in DEVICE mode */
>> +	if (enable && chip->current_role != USB_ROLE_DEVICE)
>> +		return -EINVAL;
>> +
>>  	if (enable) {
>>  		ret = enable_eud(chip);
>> -		if (!ret)
>> -			chip->enabled = enable;
>> -		else
>> -			disable_eud(chip);
>> +		if (ret) {
>> +			dev_err(chip->dev, "failed to enable eud\n");
>> +			return count;
>> +		}
>>  	} else {
>>  		disable_eud(chip);
>>  	}
>> +	chip->enabled = enable;
>>  
>>  	return count;
>>  }
>> @@ -185,11 +227,9 @@ static irqreturn_t handle_eud_irq_thread(int irq, void *data)
>>  	int ret;
>>  
>>  	if (chip->usb_attached)
>> -		ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_DEVICE);
>> +		ret = eud_usb_role_set(chip, USB_ROLE_DEVICE);
>>  	else
>> -		ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_HOST);
>> -	if (ret)
>> -		dev_err(chip->dev, "failed to set role switch\n");
>> +		ret = eud_usb_role_set(chip, USB_ROLE_HOST);
>>  
>>  	/* set and clear vbus_int_clr[0] to clear interrupt */
>>  	writel(BIT(0), chip->base + EUD_REG_VBUS_INT_CLR);
>> @@ -198,16 +238,18 @@ static irqreturn_t handle_eud_irq_thread(int irq, void *data)
>>  	return IRQ_HANDLED;
>>  }
>>  
>> -static void eud_role_switch_release(void *data)
>> +static int eud_usb_role_switch_set(struct usb_role_switch *sw,
>> +				   enum usb_role role)
>>  {
>> -	struct eud_chip *chip = data;
>> +	struct eud_chip *chip = usb_role_switch_get_drvdata(sw);
>>  
>> -	usb_role_switch_put(chip->role_sw);
>> +	return eud_usb_role_set(chip, role);
>>  }
>>  
>>  static int eud_probe(struct platform_device *pdev)
>>  {
>>  	struct eud_chip *chip;
>> +	struct usb_role_switch_desc eud_role_switch = {NULL};
>>  	int ret;
>>  
>>  	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
>> @@ -221,16 +263,6 @@ static int eud_probe(struct platform_device *pdev)
>>  		return dev_err_probe(chip->dev, PTR_ERR(chip->usb2_phy),
>>  				     "no usb2 phy configured\n");
>>  
>> -	chip->role_sw = usb_role_switch_get(&pdev->dev);
>> -	if (IS_ERR(chip->role_sw))
>> -		return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
>> -					"failed to get role switch\n");
>> -
>> -	ret = devm_add_action_or_reset(chip->dev, eud_role_switch_release, chip);
>> -	if (ret)
>> -		return dev_err_probe(chip->dev, ret,
>> -				"failed to add role switch release action\n");
>> -
>>  	chip->base = devm_platform_ioremap_resource(pdev, 0);
>>  	if (IS_ERR(chip->base))
>>  		return PTR_ERR(chip->base);
>> @@ -248,6 +280,18 @@ static int eud_probe(struct platform_device *pdev)
>>  	if (ret)
>>  		return dev_err_probe(chip->dev, ret, "failed to allocate irq\n");
>>  
>> +	eud_role_switch.fwnode = dev_fwnode(chip->dev);
>> +	eud_role_switch.set = eud_usb_role_switch_set;
>> +	eud_role_switch.get = NULL;
>> +	eud_role_switch.driver_data = chip;
>> +	chip->role_sw = usb_role_switch_register(chip->dev, &eud_role_switch);
>> +
>> +	if (IS_ERR(chip->role_sw))
>> +		return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
>> +				"failed to register role switch\n");
>> +
>> +	mutex_init(&chip->mutex);
> 
> please move mutex_init earlier.
> 

Ack
>> +
>>  	enable_irq_wake(chip->irq);
>>  
>>  	platform_set_drvdata(pdev, chip);
>> @@ -262,6 +306,9 @@ static void eud_remove(struct platform_device *pdev)
>>  	if (chip->enabled)
>>  		disable_eud(chip);
>>  
>> +	if (chip->role_sw)
>> +		usb_role_switch_unregister(chip->role_sw);
>> +
>>  	device_init_wakeup(&pdev->dev, false);
>>  	disable_irq_wake(chip->irq);
>>  }
>> -- 
>> 2.17.1
>>
>