USB: xhci: Bandwidth allocation support

Since the xHCI host controller hardware (xHC) has an internal schedule, it
needs a better representation of what devices are consuming bandwidth on
the bus.  Each device is represented by a device context, with data about
the device, endpoints, and pointers to each endpoint ring.

We need to update the endpoint information for a device context before a
new configuration or alternate interface setting is selected.  We setup an
input device context with modified endpoint information and newly
allocated endpoint rings, and then submit a Configure Endpoint Command to
the hardware.

The host controller can reject the new configuration if it exceeds the bus
bandwidth, or the host controller doesn't have enough internal resources
for the configuration.  If the command fails, we still have the older
device context with the previous configuration.  If the command succeeds,
we free the old endpoint rings.

The root hub isn't a real device, so always say yes to any bandwidth
changes for it.

The USB core will enable, disable, and then enable endpoint 0 several
times during the initialization sequence.  The device will always have an
endpoint ring for endpoint 0 and bandwidth allocated for that, unless the
device is disconnected or gets a SetAddress 0 request.  So we don't pay
attention for when xhci_check_bandwidth() is called for a re-add of
endpoint 0.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-hcd.c

@@ -530,6 +530,26 @@ unsigned int xhci_get_endpoint_index(struct usb_endpoint_descriptor *desc)
 	return index;
 }
 
+/* Find the flag for this endpoint (for use in the control context).  Use the
+ * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
+ * bit 1, etc.
+ */
+unsigned int xhci_get_endpoint_flag(struct usb_endpoint_descriptor *desc)
+{
+	return 1 << (xhci_get_endpoint_index(desc) + 1);
+}
+
+/* Compute the last valid endpoint context index.  Basically, this is the
+ * endpoint index plus one.  For slot contexts with more than valid endpoint,
+ * we find the most significant bit set in the added contexts flags.
+ * e.g. ep 1 IN (with epnum 0x81) => added_ctxs = 0b1000
+ * fls(0b1000) = 4, but the endpoint context index is 3, so subtract one.
+ */
+static inline unsigned int xhci_last_valid_endpoint(u32 added_ctxs)
+{
+	return fls(added_ctxs) - 1;
+}
+
 /* Returns 1 if the arguments are OK;
  * returns 0 this is a root hub; returns -EINVAL for NULL pointers.
  */
@@ -602,6 +622,349 @@ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
 	return -ENOSYS;
 }
 
+/* Drop an endpoint from a new bandwidth configuration for this device.
+ * Only one call to this function is allowed per endpoint before
+ * check_bandwidth() or reset_bandwidth() must be called.
+ * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
+ * add the endpoint to the schedule with possibly new parameters denoted by a
+ * different endpoint descriptor in usb_host_endpoint.
+ * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
+ * not allowed.
+ */
+int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
+		struct usb_host_endpoint *ep)
+{
+	unsigned long flags;
+	struct xhci_hcd *xhci;
+	struct xhci_device_control *in_ctx;
+	unsigned int last_ctx;
+	unsigned int ep_index;
+	struct xhci_ep_ctx *ep_ctx;
+	u32 drop_flag;
+	u32 new_add_flags, new_drop_flags, new_slot_info;
+	int ret;
+
+	ret = xhci_check_args(hcd, udev, ep, 1, __func__);
+	xhci_dbg(xhci, "%s called for udev %#x\n", __func__, (unsigned int) udev);
+	if (ret <= 0)
+		return ret;
+	xhci = hcd_to_xhci(hcd);
+
+	drop_flag = xhci_get_endpoint_flag(&ep->desc);
+	if (drop_flag == SLOT_FLAG || drop_flag == EP0_FLAG) {
+		xhci_dbg(xhci, "xHCI %s - can't drop slot or ep 0 %#x\n",
+				__func__, drop_flag);
+		return 0;
+	}
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	if (!xhci->devs || !xhci->devs[udev->slot_id]) {
+		xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
+				__func__);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return -EINVAL;
+	}
+
+	in_ctx = xhci->devs[udev->slot_id]->in_ctx;
+	ep_index = xhci_get_endpoint_index(&ep->desc);
+	ep_ctx = &xhci->devs[udev->slot_id]->out_ctx->ep[ep_index];
+	/* If the HC already knows the endpoint is disabled,
+	 * or the HCD has noted it is disabled, ignore this request
+	 */
+	if ((ep_ctx->ep_info & EP_STATE_MASK) == EP_STATE_DISABLED ||
+			in_ctx->drop_flags & xhci_get_endpoint_flag(&ep->desc)) {
+		xhci_warn(xhci, "xHCI %s called with disabled ep %#x\n",
+				__func__, (unsigned int) ep);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return 0;
+	}
+
+	in_ctx->drop_flags |= drop_flag;
+	new_drop_flags = in_ctx->drop_flags;
+
+	in_ctx->add_flags = ~drop_flag;
+	new_add_flags = in_ctx->add_flags;
+
+	last_ctx = xhci_last_valid_endpoint(in_ctx->add_flags);
+	/* Update the last valid endpoint context, if we deleted the last one */
+	if ((in_ctx->slot.dev_info & LAST_CTX_MASK) > LAST_CTX(last_ctx)) {
+		in_ctx->slot.dev_info &= ~LAST_CTX_MASK;
+		in_ctx->slot.dev_info |= LAST_CTX(last_ctx);
+	}
+	new_slot_info = in_ctx->slot.dev_info;
+
+	xhci_endpoint_zero(xhci, xhci->devs[udev->slot_id], ep);
+
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	xhci_dbg(xhci, "drop ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
+			(unsigned int) ep->desc.bEndpointAddress,
+			udev->slot_id,
+			(unsigned int) new_drop_flags,
+			(unsigned int) new_add_flags,
+			(unsigned int) new_slot_info);
+	return 0;
+}
+
+/* Add an endpoint to a new possible bandwidth configuration for this device.
+ * Only one call to this function is allowed per endpoint before
+ * check_bandwidth() or reset_bandwidth() must be called.
+ * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
+ * add the endpoint to the schedule with possibly new parameters denoted by a
+ * different endpoint descriptor in usb_host_endpoint.
+ * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
+ * not allowed.
+ */
+int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
+		struct usb_host_endpoint *ep)
+{
+	unsigned long flags;
+	struct xhci_hcd *xhci;
+	struct xhci_device_control *in_ctx;
+	unsigned int ep_index;
+	struct xhci_ep_ctx *ep_ctx;
+	u32 added_ctxs;
+	unsigned int last_ctx;
+	u32 new_add_flags, new_drop_flags, new_slot_info;
+	int ret = 0;
+
+	ret = xhci_check_args(hcd, udev, ep, 1, __func__);
+	if (ret <= 0)
+		return ret;
+	xhci = hcd_to_xhci(hcd);
+
+	added_ctxs = xhci_get_endpoint_flag(&ep->desc);
+	last_ctx = xhci_last_valid_endpoint(added_ctxs);
+	if (added_ctxs == SLOT_FLAG || added_ctxs == EP0_FLAG) {
+		/* FIXME when we have to issue an evaluate endpoint command to
+		 * deal with ep0 max packet size changing once we get the
+		 * descriptors
+		 */
+		xhci_dbg(xhci, "xHCI %s - can't add slot or ep 0 %#x\n",
+				__func__, added_ctxs);
+		return 0;
+	}
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	if (!xhci->devs || !xhci->devs[udev->slot_id]) {
+		xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
+				__func__);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return -EINVAL;
+	}
+
+	in_ctx = xhci->devs[udev->slot_id]->in_ctx;
+	ep_index = xhci_get_endpoint_index(&ep->desc);
+	ep_ctx = &xhci->devs[udev->slot_id]->out_ctx->ep[ep_index];
+	/* If the HCD has already noted the endpoint is enabled,
+	 * ignore this request.
+	 */
+	if (in_ctx->add_flags & xhci_get_endpoint_flag(&ep->desc)) {
+		xhci_warn(xhci, "xHCI %s called with enabled ep %#x\n",
+				__func__, (unsigned int) ep);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return 0;
+	}
+
+	if (xhci_endpoint_init(xhci, xhci->devs[udev->slot_id], udev, ep) < 0) {
+		dev_dbg(&udev->dev, "%s - could not initialize ep %#x\n",
+				__func__, ep->desc.bEndpointAddress);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return -ENOMEM;
+	}
+
+	in_ctx->add_flags |= added_ctxs;
+	new_add_flags = in_ctx->add_flags;
+
+	/* If xhci_endpoint_disable() was called for this endpoint, but the
+	 * xHC hasn't been notified yet through the check_bandwidth() call,
+	 * this re-adds a new state for the endpoint from the new endpoint
+	 * descriptors.  We must drop and re-add this endpoint, so we leave the
+	 * drop flags alone.
+	 */
+	new_drop_flags = in_ctx->drop_flags;
+
+	/* Update the last valid endpoint context, if we just added one past */
+	if ((in_ctx->slot.dev_info & LAST_CTX_MASK) < LAST_CTX(last_ctx)) {
+		in_ctx->slot.dev_info &= ~LAST_CTX_MASK;
+		in_ctx->slot.dev_info |= LAST_CTX(last_ctx);
+	}
+	new_slot_info = in_ctx->slot.dev_info;
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
+			(unsigned int) ep->desc.bEndpointAddress,
+			udev->slot_id,
+			(unsigned int) new_drop_flags,
+			(unsigned int) new_add_flags,
+			(unsigned int) new_slot_info);
+	return 0;
+}
+
+static void xhci_zero_in_ctx(struct xhci_virt_device *virt_dev)
+{
+	struct xhci_ep_ctx *ep_ctx;
+	int i;
+
+	/* When a device's add flag and drop flag are zero, any subsequent
+	 * configure endpoint command will leave that endpoint's state
+	 * untouched.  Make sure we don't leave any old state in the input
+	 * endpoint contexts.
+	 */
+	virt_dev->in_ctx->drop_flags = 0;
+	virt_dev->in_ctx->add_flags = 0;
+	virt_dev->in_ctx->slot.dev_info &= ~LAST_CTX_MASK;
+	/* Endpoint 0 is always valid */
+	virt_dev->in_ctx->slot.dev_info |= LAST_CTX(1);
+	for (i = 1; i < 31; ++i) {
+		ep_ctx = &virt_dev->in_ctx->ep[i];
+		ep_ctx->ep_info = 0;
+		ep_ctx->ep_info2 = 0;
+		ep_ctx->deq[0] = 0;
+		ep_ctx->deq[1] = 0;
+		ep_ctx->tx_info = 0;
+	}
+}
+
+int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
+{
+	int i;
+	int ret = 0;
+	int timeleft;
+	unsigned long flags;
+	struct xhci_hcd *xhci;
+	struct xhci_virt_device	*virt_dev;
+
+	ret = xhci_check_args(hcd, udev, NULL, 0, __func__);
+	if (ret <= 0)
+		return ret;
+	xhci = hcd_to_xhci(hcd);
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	if (!udev->slot_id || !xhci->devs || !xhci->devs[udev->slot_id]) {
+		xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
+				__func__);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return -EINVAL;
+	}
+	xhci_dbg(xhci, "%s called for udev %#x\n", __func__, (unsigned int) udev);
+	virt_dev = xhci->devs[udev->slot_id];
+
+	/* See section 4.6.6 - A0 = 1; A1 = D0 = D1 = 0 */
+	virt_dev->in_ctx->add_flags |= SLOT_FLAG;
+	virt_dev->in_ctx->add_flags &= ~EP0_FLAG;
+	virt_dev->in_ctx->drop_flags &= ~SLOT_FLAG;
+	virt_dev->in_ctx->drop_flags &= ~EP0_FLAG;
+	xhci_dbg(xhci, "New Input Control Context:\n");
+	xhci_dbg_ctx(xhci, virt_dev->in_ctx, virt_dev->in_ctx_dma,
+			LAST_CTX_TO_EP_NUM(virt_dev->in_ctx->slot.dev_info));
+
+	ret = queue_configure_endpoint(xhci, virt_dev->in_ctx_dma, udev->slot_id);
+	if (ret < 0) {
+		xhci_dbg(xhci, "FIXME allocate a new ring segment\n");
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return -ENOMEM;
+	}
+	ring_cmd_db(xhci);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	/* Wait for the configure endpoint command to complete */
+	timeleft = wait_for_completion_interruptible_timeout(
+			&virt_dev->cmd_completion,
+			USB_CTRL_SET_TIMEOUT);
+	if (timeleft <= 0) {
+		xhci_warn(xhci, "%s while waiting for configure endpoint command\n",
+				timeleft == 0 ? "Timeout" : "Signal");
+		/* FIXME cancel the configure endpoint command */
+		return -ETIME;
+	}
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	switch (virt_dev->cmd_status) {
+	case COMP_ENOMEM:
+		dev_warn(&udev->dev, "Not enough host controller resources "
+				"for new device state.\n");
+		ret = -ENOMEM;
+		/* FIXME: can we allocate more resources for the HC? */
+		break;
+	case COMP_BW_ERR:
+		dev_warn(&udev->dev, "Not enough bandwidth "
+				"for new device state.\n");
+		ret = -ENOSPC;
+		/* FIXME: can we go back to the old state? */
+		break;
+	case COMP_TRB_ERR:
+		/* the HCD set up something wrong */
+		dev_warn(&udev->dev, "ERROR: Endpoint drop flag = 0, add flag = 1, "
+				"and endpoint is not disabled.\n");
+		ret = -EINVAL;
+		break;
+	case COMP_SUCCESS:
+		dev_dbg(&udev->dev, "Successful Endpoint Configure command\n");
+		break;
+	default:
+		xhci_err(xhci, "ERROR: unexpected command completion "
+				"code 0x%x.\n", virt_dev->cmd_status);
+		ret = -EINVAL;
+		break;
+	}
+	if (ret) {
+		/* Callee should call reset_bandwidth() */
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return ret;
+	}
+
+	xhci_dbg(xhci, "Output context after successful config ep cmd:\n");
+	xhci_dbg_ctx(xhci, virt_dev->out_ctx, virt_dev->out_ctx_dma,
+			LAST_CTX_TO_EP_NUM(virt_dev->in_ctx->slot.dev_info));
+
+	xhci_zero_in_ctx(virt_dev);
+	/* Free any old rings */
+	for (i = 1; i < 31; ++i) {
+		if (virt_dev->new_ep_rings[i]) {
+			xhci_ring_free(xhci, virt_dev->ep_rings[i]);
+			virt_dev->ep_rings[i] = virt_dev->new_ep_rings[i];
+			virt_dev->new_ep_rings[i] = NULL;
+		}
+	}
+
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	return ret;
+}
+
+void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
+{
+	unsigned long flags;
+	struct xhci_hcd *xhci;
+	struct xhci_virt_device	*virt_dev;
+	int i, ret;
+
+	ret = xhci_check_args(hcd, udev, NULL, 0, __func__);
+	if (ret <= 0)
+		return;
+	xhci = hcd_to_xhci(hcd);
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	if (!xhci->devs || !xhci->devs[udev->slot_id]) {
+		xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
+				__func__);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return;
+	}
+	xhci_dbg(xhci, "%s called for udev %#x\n", __func__, (unsigned int) udev);
+	virt_dev = xhci->devs[udev->slot_id];
+	/* Free any rings allocated for added endpoints */
+	for (i = 0; i < 31; ++i) {
+		if (virt_dev->new_ep_rings[i]) {
+			xhci_ring_free(xhci, virt_dev->new_ep_rings[i]);
+			virt_dev->new_ep_rings[i] = NULL;
+		}
+	}
+	xhci_zero_in_ctx(virt_dev);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+}
+
 /*
  * At this point, the struct usb_device is about to go away, the device has
  * disconnected, and all traffic has been stopped and the endpoints have been
@@ -783,7 +1146,12 @@ int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
 	 * address given back to us by the HC.
 	 */
 	udev->devnum = (virt_dev->out_ctx->slot.dev_state & DEV_ADDR_MASK) + 1;
-	/* FIXME: Zero the input context control for later use? */
+	/* Zero the input context control for later use */
+	virt_dev->in_ctx->add_flags = 0;
+	virt_dev->in_ctx->drop_flags = 0;
+	/* Mirror flags in the output context for future ep enable/disable */
+	virt_dev->out_ctx->add_flags = SLOT_FLAG | EP0_FLAG;
+	virt_dev->out_ctx->drop_flags = 0;
 	spin_unlock_irqrestore(&xhci->lock, flags);
 
 	xhci_dbg(xhci, "Device address = %d\n", udev->devnum);