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

[Dmitry Baryshkov]

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?

> +	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.

> +
>  	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
> 

-- 
With best wishes
Dmitry