USB: xHCI: Isochronous transfer implementation

This patch implements isochronous urb enqueue and interrupt handler part.

When an isochronous urb is passed to xHCI driver, first check the transfer
ring to guarantee there is enough room for the whole urb. Then update the
start_frame and interval field of the urb. Always assume URB_ISO_ASAP
is set, and never use urb->start_frame as input.

The number of isoc TDs is equal to urb->number_of_packets. One isoc TD is
consumed every Interval. Each isoc TD consists of an Isoch TRB chained to
zero or more Normal TRBs.

Call prepare_transfer for each TD to do initialization; then calculate the
number of TRBs needed for each TD. If the data required by an isoc TD is
physically contiguous (not crosses a page boundary), then only one isoc TRB
is needed; otherwise one or more additional normal TRB shall be chained to
the isoc TRB by the host.

Set TRB_IOC to the last TRB of each isoc TD. Do not ring endpoint doorbell
to start xHC procession until all the TDs are inserted to the endpoint
transer ring.

In irq handler, update urb status and actual_length, increase
urb_priv->td_cnt. When all the TDs are completed(td_cnt is equal to
urb_priv->length), giveback the urb to usbcore.

Signed-off-by: Andiry Xu <[email protected]>
Signed-off-by: Sarah Sharp <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Andiry Xu

drivers/usb/host/xhci-ring.c

@@ -1471,6 +1471,104 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
 	return finish_td(xhci, td, event_trb, event, ep, status, false);
 }
 
+/*
+ * Process isochronous tds, update urb packet status and actual_length.
+ */
+static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
+	union xhci_trb *event_trb, struct xhci_transfer_event *event,
+	struct xhci_virt_ep *ep, int *status)
+{
+	struct xhci_ring *ep_ring;
+	struct urb_priv *urb_priv;
+	int idx;
+	int len = 0;
+	int skip_td = 0;
+	union xhci_trb *cur_trb;
+	struct xhci_segment *cur_seg;
+	u32 trb_comp_code;
+
+	ep_ring = xhci_dma_to_transfer_ring(ep, event->buffer);
+	trb_comp_code = GET_COMP_CODE(event->transfer_len);
+	urb_priv = td->urb->hcpriv;
+	idx = urb_priv->td_cnt;
+
+	if (ep->skip) {
+		/* The transfer is partly done */
+		*status = -EXDEV;
+		td->urb->iso_frame_desc[idx].status = -EXDEV;
+	} else {
+		/* handle completion code */
+		switch (trb_comp_code) {
+		case COMP_SUCCESS:
+			td->urb->iso_frame_desc[idx].status = 0;
+			xhci_dbg(xhci, "Successful isoc transfer!\n");
+			break;
+		case COMP_SHORT_TX:
+			if (td->urb->transfer_flags & URB_SHORT_NOT_OK)
+				td->urb->iso_frame_desc[idx].status =
+					 -EREMOTEIO;
+			else
+				td->urb->iso_frame_desc[idx].status = 0;
+			break;
+		case COMP_BW_OVER:
+			td->urb->iso_frame_desc[idx].status = -ECOMM;
+			skip_td = 1;
+			break;
+		case COMP_BUFF_OVER:
+		case COMP_BABBLE:
+			td->urb->iso_frame_desc[idx].status = -EOVERFLOW;
+			skip_td = 1;
+			break;
+		case COMP_STALL:
+			td->urb->iso_frame_desc[idx].status = -EPROTO;
+			skip_td = 1;
+			break;
+		case COMP_STOP:
+		case COMP_STOP_INVAL:
+			break;
+		default:
+			td->urb->iso_frame_desc[idx].status = -1;
+			break;
+		}
+	}
+
+	/* calc actual length */
+	if (ep->skip) {
+		td->urb->iso_frame_desc[idx].actual_length = 0;
+		return finish_td(xhci, td, event_trb, event, ep, status, true);
+	}
+
+	if (trb_comp_code == COMP_SUCCESS || skip_td == 1) {
+		td->urb->iso_frame_desc[idx].actual_length =
+			td->urb->iso_frame_desc[idx].length;
+		td->urb->actual_length +=
+			td->urb->iso_frame_desc[idx].length;
+	} else {
+		for (cur_trb = ep_ring->dequeue,
+		     cur_seg = ep_ring->deq_seg; cur_trb != event_trb;
+		     next_trb(xhci, ep_ring, &cur_seg, &cur_trb)) {
+			if ((cur_trb->generic.field[3] &
+			 TRB_TYPE_BITMASK) != TRB_TYPE(TRB_TR_NOOP) &&
+			    (cur_trb->generic.field[3] &
+			 TRB_TYPE_BITMASK) != TRB_TYPE(TRB_LINK))
+				len +=
+				    TRB_LEN(cur_trb->generic.field[2]);
+		}
+		len += TRB_LEN(cur_trb->generic.field[2]) -
+			TRB_LEN(event->transfer_len);
+
+		if (trb_comp_code != COMP_STOP_INVAL) {
+			td->urb->iso_frame_desc[idx].actual_length = len;
+			td->urb->actual_length += len;
+		}
+	}
+
+	if ((idx == urb_priv->length - 1) && *status == -EINPROGRESS)
+		*status = 0;
+
+	return finish_td(xhci, td, event_trb, event, ep, status, false);
+}
+
 /*
  * Process bulk and interrupt tds, update urb status and actual_length.
  */
@@ -1768,6 +1866,9 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 		if (usb_endpoint_xfer_control(&td->urb->ep->desc))
 			ret = process_ctrl_td(xhci, td, event_trb, event, ep,
 						 &status);
+		else if (usb_endpoint_xfer_isoc(&td->urb->ep->desc))
+			ret = process_isoc_td(xhci, td, event_trb, event, ep,
+						 &status);
 		else
 			ret = process_bulk_intr_td(xhci, td, event_trb, event,
 						 ep, &status);
@@ -2553,6 +2654,224 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	return 0;
 }
 
+static int count_isoc_trbs_needed(struct xhci_hcd *xhci,
+		struct urb *urb, int i)
+{
+	int num_trbs = 0;
+	u64 addr, td_len, running_total;
+
+	addr = (u64) (urb->transfer_dma + urb->iso_frame_desc[i].offset);
+	td_len = urb->iso_frame_desc[i].length;
+
+	running_total = TRB_MAX_BUFF_SIZE -
+			(addr & ((1 << TRB_MAX_BUFF_SHIFT) - 1));
+	if (running_total != 0)
+		num_trbs++;
+
+	while (running_total < td_len) {
+		num_trbs++;
+		running_total += TRB_MAX_BUFF_SIZE;
+	}
+
+	return num_trbs;
+}
+
+/* This is for isoc transfer */
+static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
+		struct urb *urb, int slot_id, unsigned int ep_index)
+{
+	struct xhci_ring *ep_ring;
+	struct urb_priv *urb_priv;
+	struct xhci_td *td;
+	int num_tds, trbs_per_td;
+	struct xhci_generic_trb *start_trb;
+	bool first_trb;
+	int start_cycle;
+	u32 field, length_field;
+	int running_total, trb_buff_len, td_len, td_remain_len, ret;
+	u64 start_addr, addr;
+	int i, j;
+
+	ep_ring = xhci->devs[slot_id]->eps[ep_index].ring;
+
+	num_tds = urb->number_of_packets;
+	if (num_tds < 1) {
+		xhci_dbg(xhci, "Isoc URB with zero packets?\n");
+		return -EINVAL;
+	}
+
+	if (!in_interrupt())
+		dev_dbg(&urb->dev->dev, "ep %#x - urb len = %#x (%d),"
+				" addr = %#llx, num_tds = %d\n",
+				urb->ep->desc.bEndpointAddress,
+				urb->transfer_buffer_length,
+				urb->transfer_buffer_length,
+				(unsigned long long)urb->transfer_dma,
+				num_tds);
+
+	start_addr = (u64) urb->transfer_dma;
+	start_trb = &ep_ring->enqueue->generic;
+	start_cycle = ep_ring->cycle_state;
+
+	/* Queue the first TRB, even if it's zero-length */
+	for (i = 0; i < num_tds; i++) {
+		first_trb = true;
+
+		running_total = 0;
+		addr = start_addr + urb->iso_frame_desc[i].offset;
+		td_len = urb->iso_frame_desc[i].length;
+		td_remain_len = td_len;
+
+		trbs_per_td = count_isoc_trbs_needed(xhci, urb, i);
+
+		ret = prepare_transfer(xhci, xhci->devs[slot_id], ep_index,
+				urb->stream_id, trbs_per_td, urb, i, mem_flags);
+		if (ret < 0)
+			return ret;
+
+		urb_priv = urb->hcpriv;
+		td = urb_priv->td[i];
+
+		for (j = 0; j < trbs_per_td; j++) {
+			u32 remainder = 0;
+			field = 0;
+
+			if (first_trb) {
+				/* Queue the isoc TRB */
+				field |= TRB_TYPE(TRB_ISOC);
+				/* Assume URB_ISO_ASAP is set */
+				field |= TRB_SIA;
+				if (i > 0)
+					field |= ep_ring->cycle_state;
+				first_trb = false;
+			} else {
+				/* Queue other normal TRBs */
+				field |= TRB_TYPE(TRB_NORMAL);
+				field |= ep_ring->cycle_state;
+			}
+
+			/* Chain all the TRBs together; clear the chain bit in
+			 * the last TRB to indicate it's the last TRB in the
+			 * chain.
+			 */
+			if (j < trbs_per_td - 1) {
+				field |= TRB_CHAIN;
+			} else {
+				td->last_trb = ep_ring->enqueue;
+				field |= TRB_IOC;
+			}
+
+			/* Calculate TRB length */
+			trb_buff_len = TRB_MAX_BUFF_SIZE -
+				(addr & ((1 << TRB_MAX_BUFF_SHIFT) - 1));
+			if (trb_buff_len > td_remain_len)
+				trb_buff_len = td_remain_len;
+
+			remainder = xhci_td_remainder(td_len - running_total);
+			length_field = TRB_LEN(trb_buff_len) |
+				remainder |
+				TRB_INTR_TARGET(0);
+			queue_trb(xhci, ep_ring, false, false,
+				lower_32_bits(addr),
+				upper_32_bits(addr),
+				length_field,
+				/* We always want to know if the TRB was short,
+				 * or we won't get an event when it completes.
+				 * (Unless we use event data TRBs, which are a
+				 * waste of space and HC resources.)
+				 */
+				field | TRB_ISP);
+			running_total += trb_buff_len;
+
+			addr += trb_buff_len;
+			td_remain_len -= trb_buff_len;
+		}
+
+		/* Check TD length */
+		if (running_total != td_len) {
+			xhci_err(xhci, "ISOC TD length unmatch\n");
+			return -EINVAL;
+		}
+	}
+
+	wmb();
+	start_trb->field[3] |= start_cycle;
+
+	ring_ep_doorbell(xhci, slot_id, ep_index, urb->stream_id);
+	return 0;
+}
+
+/*
+ * Check transfer ring to guarantee there is enough room for the urb.
+ * Update ISO URB start_frame and interval.
+ * Update interval as xhci_queue_intr_tx does. Just use xhci frame_index to
+ * update the urb->start_frame by now.
+ * Always assume URB_ISO_ASAP set, and NEVER use urb->start_frame as input.
+ */
+int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
+		struct urb *urb, int slot_id, unsigned int ep_index)
+{
+	struct xhci_virt_device *xdev;
+	struct xhci_ring *ep_ring;
+	struct xhci_ep_ctx *ep_ctx;
+	int start_frame;
+	int xhci_interval;
+	int ep_interval;
+	int num_tds, num_trbs, i;
+	int ret;
+
+	xdev = xhci->devs[slot_id];
+	ep_ring = xdev->eps[ep_index].ring;
+	ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);
+
+	num_trbs = 0;
+	num_tds = urb->number_of_packets;
+	for (i = 0; i < num_tds; i++)
+		num_trbs += count_isoc_trbs_needed(xhci, urb, i);
+
+	/* Check the ring to guarantee there is enough room for the whole urb.
+	 * Do not insert any td of the urb to the ring if the check failed.
+	 */
+	ret = prepare_ring(xhci, ep_ring, ep_ctx->ep_info & EP_STATE_MASK,
+				num_trbs, mem_flags);
+	if (ret)
+		return ret;
+
+	start_frame = xhci_readl(xhci, &xhci->run_regs->microframe_index);
+	start_frame &= 0x3fff;
+
+	urb->start_frame = start_frame;
+	if (urb->dev->speed == USB_SPEED_LOW ||
+			urb->dev->speed == USB_SPEED_FULL)
+		urb->start_frame >>= 3;
+
+	xhci_interval = EP_INTERVAL_TO_UFRAMES(ep_ctx->ep_info);
+	ep_interval = urb->interval;
+	/* Convert to microframes */
+	if (urb->dev->speed == USB_SPEED_LOW ||
+			urb->dev->speed == USB_SPEED_FULL)
+		ep_interval *= 8;
+	/* FIXME change this to a warning and a suggestion to use the new API
+	 * to set the polling interval (once the API is added).
+	 */
+	if (xhci_interval != ep_interval) {
+		if (!printk_ratelimit())
+			dev_dbg(&urb->dev->dev, "Driver uses different interval"
+					" (%d microframe%s) than xHCI "
+					"(%d microframe%s)\n",
+					ep_interval,
+					ep_interval == 1 ? "" : "s",
+					xhci_interval,
+					xhci_interval == 1 ? "" : "s");
+		urb->interval = xhci_interval;
+		/* Convert back to frames for LS/FS devices */
+		if (urb->dev->speed == USB_SPEED_LOW ||
+				urb->dev->speed == USB_SPEED_FULL)
+			urb->interval /= 8;
+	}
+	return xhci_queue_isoc_tx(xhci, GFP_ATOMIC, urb, slot_id, ep_index);
+}
+
 /****		Command Ring Operations		****/
 
 /* Generic function for queueing a command TRB on the command ring.

drivers/usb/host/xhci.h

@@ -919,6 +919,9 @@ struct xhci_event_cmd {
 /* Control transfer TRB specific fields */
 #define TRB_DIR_IN		(1<<16)
 
+/* Isochronous TRB specific fields */
+#define TRB_SIA			(1<<31)
+
 struct xhci_generic_trb {
 	u32 field[4];
 };
@@ -1416,6 +1419,8 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags, struct urb *urb,
 		int slot_id, unsigned int ep_index);
 int xhci_queue_intr_tx(struct xhci_hcd *xhci, gfp_t mem_flags, struct urb *urb,
 		int slot_id, unsigned int ep_index);
+int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
+		struct urb *urb, int slot_id, unsigned int ep_index);
 int xhci_queue_configure_endpoint(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,
 		u32 slot_id, bool command_must_succeed);
 int xhci_queue_evaluate_context(struct xhci_hcd *xhci, dma_addr_t in_ctx_ptr,