[PATCH] xhci: create one unified function to calculate TRB TD remainder.

[Mathias Nyman <mathias.nyman-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

xhci versions 1.0 and later report the untransferred data remaining in a
TD a bit differently than older hosts.

We used to have separate functions for these, and needed to check host
 version before calling the right function.

Now Mediatek host has an additional quirk on how it uses the TD Size
field for remaining data. To prevent yet another function for calculating
remainder we instead want to make one quirk friendly unified function.

Signed-off-by: Mathias Nyman <mathias.nyman-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/usb/host/xhci-ring.c | 106 ++++++++++++++++++-------------------------
 drivers/usb/host/xhci.h      |   2 +
 2 files changed, 46 insertions(+), 62 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index a47a1e8..57f40a1 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3020,21 +3020,6 @@ int xhci_queue_intr_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 }
 
 /*
- * The TD size is the number of bytes remaining in the TD (including this TRB),
- * right shifted by 10.
- * It must fit in bits 21:17, so it can't be bigger than 31.
- */
-static u32 xhci_td_remainder(unsigned int remainder)
-{
-	u32 max = (1 << (21 - 17 + 1)) - 1;
-
-	if ((remainder >> 10) >= max)
-		return max << 17;
-	else
-		return (remainder >> 10) << 17;
-}
-
-/*
  * For xHCI 1.0 host controllers, TD size is the number of max packet sized
  * packets remaining in the TD (*not* including this TRB).
  *
@@ -3046,30 +3031,36 @@ static u32 xhci_td_remainder(unsigned int remainder)
  *
  * TD size = total_packet_count - packets_transferred
  *
- * It must fit in bits 21:17, so it can't be bigger than 31.
+ * For xHCI 0.96 and older, TD size field should be the remaining bytes
+ * including this TRB, right shifted by 10
+ *
+ * For all hosts it must fit in bits 21:17, so it can't be bigger than 31.
+ * This is taken care of in the TRB_TD_SIZE() macro
+ *
  * The last TRB in a TD must have the TD size set to zero.
  */
-static u32 xhci_v1_0_td_remainder(int running_total, int trb_buff_len,
-		unsigned int total_packet_count, struct urb *urb,
-		unsigned int num_trbs_left)
+static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred,
+			      int trb_buff_len, unsigned int td_total_len,
+			      struct urb *urb, unsigned int num_trbs_left)
 {
-	int packets_transferred;
+	u32 maxp, total_packet_count;
+
+	if (xhci->hci_version < 0x100)
+		return ((td_total_len - transferred) >> 10);
+
+	maxp = GET_MAX_PACKET(usb_endpoint_maxp(&urb->ep->desc));
+	total_packet_count = DIV_ROUND_UP(td_total_len, maxp);
 
 	/* One TRB with a zero-length data packet. */
-	if (num_trbs_left == 0 || (running_total == 0 && trb_buff_len == 0))
+	if (num_trbs_left == 0 || (transferred == 0 && trb_buff_len == 0) ||
+	    trb_buff_len == td_total_len)
 		return 0;
 
-	/* All the TRB queueing functions don't count the current TRB in
-	 * running_total.
-	 */
-	packets_transferred = (running_total + trb_buff_len) /
-		GET_MAX_PACKET(usb_endpoint_maxp(&urb->ep->desc));
-
-	if ((total_packet_count - packets_transferred) > 31)
-		return 31 << 17;
-	return (total_packet_count - packets_transferred) << 17;
+	/* Queueing functions don't count the current TRB into transferred */
+	return (total_packet_count - ((transferred + trb_buff_len) / maxp));
 }
 
+
 static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		struct urb *urb, int slot_id, unsigned int ep_index)
 {
@@ -3191,17 +3182,12 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		}
 
 		/* Set the TRB length, TD size, and interrupter fields. */
-		if (xhci->hci_version < 0x100) {
-			remainder = xhci_td_remainder(
-					urb->transfer_buffer_length -
-					running_total);
-		} else {
-			remainder = xhci_v1_0_td_remainder(running_total,
-					trb_buff_len, total_packet_count, urb,
-					num_trbs - 1);
-		}
+		remainder = xhci_td_remainder(xhci, running_total, trb_buff_len,
+					   urb->transfer_buffer_length,
+					   urb, num_trbs - 1);
+
 		length_field = TRB_LEN(trb_buff_len) |
-			remainder |
+			TRB_TD_SIZE(remainder) |
 			TRB_INTR_TARGET(0);
 
 		if (num_trbs > 1)
@@ -3364,17 +3350,12 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			field |= TRB_ISP;
 
 		/* Set the TRB length, TD size, and interrupter fields. */
-		if (xhci->hci_version < 0x100) {
-			remainder = xhci_td_remainder(
-					urb->transfer_buffer_length -
-					running_total);
-		} else {
-			remainder = xhci_v1_0_td_remainder(running_total,
-					trb_buff_len, total_packet_count, urb,
-					num_trbs - 1);
-		}
+		remainder = xhci_td_remainder(xhci, running_total, trb_buff_len,
+					   urb->transfer_buffer_length,
+					   urb, num_trbs - 1);
+
 		length_field = TRB_LEN(trb_buff_len) |
-			remainder |
+			TRB_TD_SIZE(remainder) |
 			TRB_INTR_TARGET(0);
 
 		if (num_trbs > 1)
@@ -3412,7 +3393,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	struct usb_ctrlrequest *setup;
 	struct xhci_generic_trb *start_trb;
 	int start_cycle;
-	u32 field, length_field;
+	u32 field, length_field, remainder;
 	struct urb_priv *urb_priv;
 	struct xhci_td *td;
 
@@ -3485,9 +3466,15 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	else
 		field = TRB_TYPE(TRB_DATA);
 
+	remainder = xhci_td_remainder(xhci, 0,
+				   urb->transfer_buffer_length,
+				   urb->transfer_buffer_length,
+				   urb, 1);
+
 	length_field = TRB_LEN(urb->transfer_buffer_length) |
-		xhci_td_remainder(urb->transfer_buffer_length) |
+		TRB_TD_SIZE(remainder) |
 		TRB_INTR_TARGET(0);
+
 	if (urb->transfer_buffer_length > 0) {
 		if (setup->bRequestType & USB_DIR_IN)
 			field |= TRB_DIR_IN;
@@ -3816,17 +3803,12 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 				trb_buff_len = td_remain_len;
 
 			/* Set the TRB length, TD size, & interrupter fields. */
-			if (xhci->hci_version < 0x100) {
-				remainder = xhci_td_remainder(
-						td_len - running_total);
-			} else {
-				remainder = xhci_v1_0_td_remainder(
-						running_total, trb_buff_len,
-						total_packet_count, urb,
-						(trbs_per_td - j - 1));
-			}
+			remainder = xhci_td_remainder(xhci, running_total,
+						   trb_buff_len, td_len,
+						   urb, trbs_per_td - j - 1);
+
 			length_field = TRB_LEN(trb_buff_len) |
-				remainder |
+				TRB_TD_SIZE(remainder) |
 				TRB_INTR_TARGET(0);
 
 			queue_trb(xhci, ep_ring, more_trbs_coming,
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index dbda41e..ea8b904 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1136,6 +1136,8 @@ enum xhci_setup_dev {
 /* Normal TRB fields */
 /* transfer_len bitmasks - bits 0:16 */
 #define	TRB_LEN(p)		((p) & 0x1ffff)
+/* TD Size, packets remaining in this TD, bits 21:17 (5 bits, so max 31) */
+#define TRB_TD_SIZE(p)          (min((p), (u32)31) << 17)
 /* Interrupter Target - which MSI-X vector to target the completion event at */
 #define TRB_INTR_TARGET(p)	(((p) & 0x3ff) << 22)
 #define GET_INTR_TARGET(p)	(((p) >> 22) & 0x3ff)
-- 
1.9.1