Re: [PATCH v3 3/3] usb: gadget: udc: renesas_usb3: add support for usb role swap

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> writes:
> This patch adds support for usb role swap via sysfs "role".
>
> For example:
>  1) Connect a usb cable using 2 Salvator-X boards.
>   - For A-Device, the cable is connected to CN11 (USB3.0 ch0).
>   - For B-Device, the cable is connected to CN9 (USB2.0 ch0).
>  2) On A-Device, you input the following command:
>   # echo peripheral > /sys/devices/platform/soc/ee020000.usb/role
>  3) On B-Device, you input the following command:
>   # echo host > /sys/devices/platform/soc/ee080200.usb-phy/role
>
> Then, the A-Device acts as a peripheral and the B-Device acts as
> a host. Please note that A-Device must input the following command
> if you want the board to act as a host again.
>  # echo host > /sys/devices/platform/soc/ee020000.usb/role
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  .../ABI/testing/sysfs-platform-renesas_usb3        | 15 ++++++
>  drivers/usb/gadget/udc/renesas_usb3.c              | 56 ++++++++++++++++++++++
>  2 files changed, 71 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-platform-renesas_usb3
>
> diff --git a/Documentation/ABI/testing/sysfs-platform-renesas_usb3 b/Documentation/ABI/testing/sysfs-platform-renesas_usb3
> new file mode 100644
> index 0000000..1f63190
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-platform-renesas_usb3
> @@ -0,0 +1,15 @@
> +What:		/sys/devices/platform/<udc-name>/role

I have one question here. This seems to imply that platform devices have
a "role" file which is not true for all platforms devices. I really
don't have a suggestion as to how this could/should be written out,
though :-s

Greg, any suggestions?

(keeping patch below for reference only)

> +Date:		March 2017
> +KernelVersion:	4.13
> +Contact:	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> +Description:
> +		This file can be read and write.
> +		The file can show/change the drd mode of usb.
> +
> +		Write the following string to change the mode:
> +		 "host" - switching mode from peripheral to host.
> +		 "peripheral" - switching mode from host to peripheral.
> +
> +		Read the file, then it shows the following strings:
> +		 "host" - The mode is host now.
> +		 "peripheral" - The mode is peripheral now.
> diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
> index a1e79fc..5a2d845 100644
> --- a/drivers/usb/gadget/udc/renesas_usb3.c
> +++ b/drivers/usb/gadget/udc/renesas_usb3.c
> @@ -372,6 +372,11 @@ static void usb3_disable_pipe_irq(struct renesas_usb3 *usb3, int num)
>  	usb3_clear_bit(usb3, USB_INT_2_PIPE(num), USB3_USB_INT_ENA_2);
>  }
>  
> +static bool usb3_is_host(struct renesas_usb3 *usb3)
> +{
> +	return !(usb3_read(usb3, USB3_DRD_CON) & DRD_CON_PERI_CON);
> +}
> +
>  static void usb3_init_axi_bridge(struct renesas_usb3 *usb3)
>  {
>  	/* Set AXI_INT */
> @@ -576,8 +581,14 @@ static void usb3_vbus_out(struct renesas_usb3 *usb3, bool enable)
>  
>  static void usb3_mode_config(struct renesas_usb3 *usb3, bool host, bool a_dev)
>  {
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&usb3->lock, flags);
>  	usb3_set_mode(usb3, host);
>  	usb3_vbus_out(usb3, a_dev);
> +	if (!host && a_dev)		/* for A-Peripheral */
> +		usb3_connect(usb3);
> +	spin_unlock_irqrestore(&usb3->lock, flags);
>  }
>  
>  static bool usb3_is_a_device(struct renesas_usb3 *usb3)
> @@ -1837,11 +1848,49 @@ static int renesas_usb3_set_selfpowered(struct usb_gadget *gadget, int is_self)
>  	.set_selfpowered	= renesas_usb3_set_selfpowered,
>  };
>  
> +static ssize_t role_store(struct device *dev, struct device_attribute *attr,
> +			  const char *buf, size_t count)
> +{
> +	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
> +	bool new_mode_is_host;
> +
> +	if (!usb3->driver)
> +		return -ENODEV;
> +
> +	if (!strncmp(buf, "host", strlen("host")))
> +		new_mode_is_host = true;
> +	else if (!strncmp(buf, "peripheral", strlen("peripheral")))
> +		new_mode_is_host = false;
> +	else
> +		return -EINVAL;
> +
> +	if (new_mode_is_host == usb3_is_host(usb3))
> +		return -EINVAL;
> +
> +	usb3_mode_config(usb3, new_mode_is_host, usb3_is_a_device(usb3));
> +
> +	return count;
> +}
> +
> +static ssize_t role_show(struct device *dev, struct device_attribute *attr,
> +			 char *buf)
> +{
> +	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
> +
> +	if (!usb3->driver)
> +		return -ENODEV;
> +
> +	return sprintf(buf, "%s\n", usb3_is_host(usb3) ? "host" : "peripheral");
> +}
> +static DEVICE_ATTR_RW(role);
> +
>  /*------- platform_driver ------------------------------------------------*/
>  static int renesas_usb3_remove(struct platform_device *pdev)
>  {
>  	struct renesas_usb3 *usb3 = platform_get_drvdata(pdev);
>  
> +	device_remove_file(&pdev->dev, &dev_attr_role);
> +
>  	pm_runtime_put(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  
> @@ -2044,6 +2093,10 @@ static int renesas_usb3_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto err_add_udc;
>  
> +	ret = device_create_file(&pdev->dev, &dev_attr_role);
> +	if (ret < 0)
> +		goto err_dev_create;
> +
>  	usb3->workaround_for_vbus = priv->workaround_for_vbus;
>  
>  	pm_runtime_enable(&pdev->dev);
> @@ -2053,6 +2106,9 @@ static int renesas_usb3_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> +err_dev_create:
> +	usb_del_gadget_udc(&usb3->gadget);
> +
>  err_add_udc:
>  	__renesas_usb3_ep_free_request(usb3->ep0_req);
>  
> -- 
> 1.9.1
>
> --
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-- 
balbi

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