[PATCH] usb: xhci-dwc3: Support role switch default role

[Mark Kettenis]

> From: Mark Kettenis <kettenis at openbsd.org>
> Date: Tue, 19 Apr 2022 21:06:33 +0200
> 
> When the device tree indicates support for role switching through
> the "usb-role-switch" property, take the "role-switch-default-mode"
> property into account when deciding which role to put the
> controller into.
> 
> This makes USB devices work on Apple M1 systems where the device
> tree may include a "dr_mode" property that is set to "otg", but
> where we need to put the controller into "host" mode to see
> devices connected to the type-C ports.
> 
> Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> ---
>  drivers/usb/common/common.c  | 16 ++++++++++++++++
>  drivers/usb/host/xhci-dwc3.c |  6 ++++++
>  include/linux/usb/otg.h      | 10 ++++++++++
>  3 files changed, 32 insertions(+)

Ping?

> diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
> index ee0c064f1f..cff86a51ae 100644
> --- a/drivers/usb/common/common.c
> +++ b/drivers/usb/common/common.c
> @@ -40,6 +40,22 @@ enum usb_dr_mode usb_get_dr_mode(ofnode node)
>  	return USB_DR_MODE_UNKNOWN;
>  }
>  
> +enum usb_dr_mode usb_get_role_switch_default_mode(ofnode node)
> +{
> +	const char *dr_mode;
> +	int i;
> +
> +	dr_mode = ofnode_read_string(node, "role-switch-default-mode");
> +	if (!dr_mode)
> +		return USB_DR_MODE_UNKNOWN;
> +
> +	for (i = 0; i < ARRAY_SIZE(usb_dr_modes); i++)
> +		if (!strcmp(dr_mode, usb_dr_modes[i]))
> +			return i;
> +
> +	return USB_DR_MODE_UNKNOWN;
> +}
> +
>  static const char *const speed_names[] = {
>  	[USB_SPEED_UNKNOWN] = "UNKNOWN",
>  	[USB_SPEED_LOW] = "low-speed",
> diff --git a/drivers/usb/host/xhci-dwc3.c b/drivers/usb/host/xhci-dwc3.c
> index bec0d98081..1dbd65dfaa 100644
> --- a/drivers/usb/host/xhci-dwc3.c
> +++ b/drivers/usb/host/xhci-dwc3.c
> @@ -209,6 +209,12 @@ static int xhci_dwc3_probe(struct udevice *dev)
>  	writel(reg, &dwc3_reg->g_usb2phycfg[0]);
>  
>  	dr_mode = usb_get_dr_mode(dev_ofnode(dev));
> +	if (dr_mode == USB_DR_MODE_OTG &&
> +	    dev_read_bool(dev, "usb-role-switch")) {
> +		dr_mode = usb_get_role_switch_default_mode(dev_ofnode(dev));
> +		if (dr_mode == USB_DR_MODE_UNKNOWN)
> +			dr_mode = USB_DR_MODE_OTG;
> +	}
>  	if (dr_mode == USB_DR_MODE_UNKNOWN)
>  		/* by default set dual role mode to HOST */
>  		dr_mode = USB_DR_MODE_HOST;
> diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h
> index c19b916be9..5d0dac950e 100644
> --- a/include/linux/usb/otg.h
> +++ b/include/linux/usb/otg.h
> @@ -27,6 +27,16 @@ enum usb_dr_mode {
>   */
>  enum usb_dr_mode usb_get_dr_mode(ofnode node);
>  
> +/**
> + * usb_get_dr_mode() - Get dual role mode for given device
> + * @node: ofnode of the given device
> + *
> + * The function gets phy interface string from property
> + * 'role-switch-defaulr-mode', and returns the correspondig enum
> + * usb_dr_mode
> + */
> +enum usb_dr_mode usb_get_role_switch_default_mode(ofnode node);
> +
>  /**
>   * usb_get_maximum_speed() - Get maximum speed for given device
>   * @node: ofnode of the given device
> -- 
> 2.35.1
> 
>