Re: [PATCH v3 2/5] usb: dwc3: Add remote wakeup handling

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Mon, Feb 06, 2023, Elson Roy Serrao wrote:
> An usb device can initate a remote wakeup and bring the link out of
> suspend as dictated by the DEVICE_REMOTE_WAKEUP feature selector.
> Add support to handle this packet and set the remote wakeup capability.
> 
> Some hosts may take longer time to initiate the resume signaling after
> device triggers a remote wakeup. So add async support to the wakeup API
> by enabling link status change events.
> 
> Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
> ---
>  drivers/usb/dwc3/core.h   |  2 ++
>  drivers/usb/dwc3/ep0.c    |  4 +++
>  drivers/usb/dwc3/gadget.c | 73 ++++++++++++++++++++++++++++++++++++++++++-----
>  3 files changed, 72 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 8f9959b..ff6e6f6 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1110,6 +1110,7 @@ struct dwc3_scratchpad_array {
>   *	3	- Reserved
>   * @dis_metastability_quirk: set to disable metastability quirk.
>   * @dis_split_quirk: set to disable split boundary.
> + * @rw_configured: set if the device is configured for remote wakeup.
>   * @imod_interval: set the interrupt moderation interval in 250ns
>   *			increments or 0 to disable.
>   * @max_cfg_eps: current max number of IN eps used across all USB configs.
> @@ -1326,6 +1327,7 @@ struct dwc3 {
>  
>  	unsigned		dis_split_quirk:1;
>  	unsigned		async_callbacks:1;
> +	unsigned		rw_configured:1;
>  
>  	u16			imod_interval;
>  
> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> index 61de693..cd7c0cb 100644
> --- a/drivers/usb/dwc3/ep0.c
> +++ b/drivers/usb/dwc3/ep0.c
> @@ -356,6 +356,9 @@ static int dwc3_ep0_handle_status(struct dwc3 *dwc,
>  				usb_status |= 1 << USB_DEV_STAT_U1_ENABLED;
>  			if (reg & DWC3_DCTL_INITU2ENA)
>  				usb_status |= 1 << USB_DEV_STAT_U2_ENABLED;
> +		} else {
> +			usb_status |= dwc->gadget->rw_armed <<
> +					USB_DEVICE_REMOTE_WAKEUP;
>  		}
>  
>  		break;
> @@ -476,6 +479,7 @@ static int dwc3_ep0_handle_device(struct dwc3 *dwc,
>  
>  	switch (wValue) {
>  	case USB_DEVICE_REMOTE_WAKEUP:
> +		dwc->gadget->rw_armed = set;
>  		break;
>  	/*
>  	 * 9.4.1 says only for SS, in AddressState only for
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 89dcfac..d0b9917 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -258,7 +258,7 @@ int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
>  	return ret;
>  }
>  
> -static int __dwc3_gadget_wakeup(struct dwc3 *dwc);
> +static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async);
>  
>  /**
>   * dwc3_send_gadget_ep_cmd - issue an endpoint command
> @@ -325,7 +325,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
>  
>  			fallthrough;
>  		case DWC3_LINK_STATE_U3:
> -			ret = __dwc3_gadget_wakeup(dwc);
> +			ret = __dwc3_gadget_wakeup(dwc, false);
>  			dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
>  					ret);
>  			break;
> @@ -2269,6 +2269,19 @@ static const struct usb_ep_ops dwc3_gadget_ep_ops = {
>  
>  /* -------------------------------------------------------------------------- */
>  
> +static void dwc3_gadget_enable_linksts_evts(struct dwc3 *dwc, bool set)
> +{
> +	u32 reg;

Add a check here to prevent disabling link state event if the controller
is dwc_usb3 2.50a. Some older controller always enables this event for a
quirk.

> +
> +	reg = dwc3_readl(dwc->regs, DWC3_DEVTEN);
> +	if (set)
> +		reg |= DWC3_DEVTEN_ULSTCNGEN;
> +	else
> +		reg &= ~DWC3_DEVTEN_ULSTCNGEN;
> +
> +	dwc3_writel(dwc->regs, DWC3_DEVTEN, reg);
> +}
> +
>  static int dwc3_gadget_get_frame(struct usb_gadget *g)
>  {
>  	struct dwc3		*dwc = gadget_to_dwc(g);
> @@ -2276,7 +2289,7 @@ static int dwc3_gadget_get_frame(struct usb_gadget *g)
>  	return __dwc3_gadget_get_frame(dwc);
>  }
>  
> -static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
> +static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async)
>  {
>  	int			retries;
>  
> @@ -2296,9 +2309,14 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
>  	link_state = DWC3_DSTS_USBLNKST(reg);
>  
>  	switch (link_state) {
> +	case DWC3_LINK_STATE_U3:	/* in HS, means SUSPEND */

It's also possible to do remote wakeup in L1 for highspeed.

> +		if (!dwc->rw_configured) {
> +			dev_err(dwc->dev,
> +				"device not configured for remote wakeup\n");
> +			return -EINVAL;
> +		}
>  	case DWC3_LINK_STATE_RESET:
>  	case DWC3_LINK_STATE_RX_DET:	/* in HS, means Early Suspend */
> -	case DWC3_LINK_STATE_U3:	/* in HS, means SUSPEND */
>  	case DWC3_LINK_STATE_U2:	/* in HS, means Sleep (L1) */
>  	case DWC3_LINK_STATE_U1:
>  	case DWC3_LINK_STATE_RESUME:
> @@ -2307,9 +2325,13 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
>  		return -EINVAL;
>  	}
>  
> +	if (async)
> +		dwc3_gadget_enable_linksts_evts(dwc, true);
> +
>  	ret = dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RECOV);
>  	if (ret < 0) {
>  		dev_err(dwc->dev, "failed to put link in Recovery\n");
> +		dwc3_gadget_enable_linksts_evts(dwc, false);
>  		return ret;
>  	}
>  
> @@ -2321,6 +2343,13 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
>  		dwc3_writel(dwc->regs, DWC3_DCTL, reg);
>  	}
>  
> +	/*
> +	 * Since link status change events are enabled we will receive
> +	 * an U0 event when wakeup is successful. So bail out.
> +	 */
> +	if (async)
> +		return 0;
> +
>  	/* poll until Link State changes to ON */
>  	retries = 20000;
>  
> @@ -2347,12 +2376,30 @@ static int dwc3_gadget_wakeup(struct usb_gadget *g)
>  	int			ret;
>  
>  	spin_lock_irqsave(&dwc->lock, flags);
> -	ret = __dwc3_gadget_wakeup(dwc);
> +	if (!dwc->gadget->rw_armed) {
> +		dev_err(dwc->dev, "%s:remote wakeup not enabled\n", __func__);
> +		spin_unlock_irqrestore(&dwc->lock, flags);
> +		return -EINVAL;
> +	}
> +	ret = __dwc3_gadget_wakeup(dwc, true);
> +
>  	spin_unlock_irqrestore(&dwc->lock, flags);
>  
>  	return ret;
>  }
>  
> +static int dwc3_gadget_set_remotewakeup(struct usb_gadget *g, int set)
> +{
> +	struct dwc3		*dwc = gadget_to_dwc(g);
> +	unsigned long		flags;
> +
> +	spin_lock_irqsave(&dwc->lock, flags);
> +	dwc->rw_configured = !!set;
> +	spin_unlock_irqrestore(&dwc->lock, flags);
> +
> +	return 0;
> +}
> +
>  static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
>  		int is_selfpowered)
>  {
> @@ -2978,6 +3025,7 @@ static void dwc3_gadget_async_callbacks(struct usb_gadget *g, bool enable)
>  static const struct usb_gadget_ops dwc3_gadget_ops = {
>  	.get_frame		= dwc3_gadget_get_frame,
>  	.wakeup			= dwc3_gadget_wakeup,
> +	.set_remotewakeup	= dwc3_gadget_set_remotewakeup,
>  	.set_selfpowered	= dwc3_gadget_set_selfpowered,
>  	.pullup			= dwc3_gadget_pullup,
>  	.udc_start		= dwc3_gadget_start,
> @@ -3821,6 +3869,8 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
>  
>  	dwc->gadget->speed = USB_SPEED_UNKNOWN;
>  	dwc->setup_packet_pending = false;
> +	dwc->gadget->rw_armed = false;
> +	dwc3_gadget_enable_linksts_evts(dwc, false);
>  	usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
>  
>  	if (dwc->ep0state != EP0_SETUP_PHASE) {
> @@ -3914,6 +3964,8 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
>  	reg &= ~DWC3_DCTL_TSTCTRL_MASK;
>  	dwc3_gadget_dctl_write_safe(dwc, reg);
>  	dwc->test_mode = false;
> +	dwc->gadget->rw_armed = false;
> +	dwc3_gadget_enable_linksts_evts(dwc, false);
>  	dwc3_clear_stall_all_ep(dwc);
>  
>  	/* Reset device address to zero */
> @@ -4066,7 +4118,7 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
>  	 */
>  }
>  
> -static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
> +static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc, unsigned int evtinfo)
>  {
>  	/*
>  	 * TODO take core out of low power mode when that's
> @@ -4078,6 +4130,8 @@ static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
>  		dwc->gadget_driver->resume(dwc->gadget);
>  		spin_lock(&dwc->lock);
>  	}
> +
> +	dwc->link_state = evtinfo & DWC3_LINK_STATE_MASK;
>  }
>  
>  static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
> @@ -4159,6 +4213,10 @@ static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
>  	}
>  
>  	switch (next) {
> +	case DWC3_LINK_STATE_U0:
> +		dwc3_gadget_enable_linksts_evts(dwc, false);
> +		dwc3_resume_gadget(dwc);
> +		break;
>  	case DWC3_LINK_STATE_U1:
>  		if (dwc->speed == USB_SPEED_SUPER)
>  			dwc3_suspend_gadget(dwc);
> @@ -4227,7 +4285,7 @@ static void dwc3_gadget_interrupt(struct dwc3 *dwc,
>  		dwc3_gadget_conndone_interrupt(dwc);
>  		break;
>  	case DWC3_DEVICE_EVENT_WAKEUP:
> -		dwc3_gadget_wakeup_interrupt(dwc);
> +		dwc3_gadget_wakeup_interrupt(dwc, event->event_info);
>  		break;
>  	case DWC3_DEVICE_EVENT_HIBER_REQ:
>  		if (dev_WARN_ONCE(dwc->dev, !dwc->has_hibernation,
> @@ -4487,6 +4545,7 @@ int dwc3_gadget_init(struct dwc3 *dwc)
>  	dwc->gadget->sg_supported	= true;
>  	dwc->gadget->name		= "dwc3-gadget";
>  	dwc->gadget->lpm_capable	= !dwc->usb2_gadget_lpm_disable;
> +	dwc->gadget->rw_capable		= dwc->gadget->ops->wakeup ? true : false;

Just set it to true here.

>  
>  	/*
>  	 * FIXME We might be setting max_speed to <SUPER, however versions
> -- 
> 2.7.4
> 

Thanks,
Thinh