USB: UHCI: add native scatter-gather support(v1)

This patch adds native scatter-gather support to uhci-hcd.

Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 29 insertions, 4 deletions

diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index d3ade4018487..2090b45eb606 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -917,10 +917,13 @@ static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
         unsigned long destination, status;
         int maxsze = le16_to_cpu(qh->hep->desc.wMaxPacketSize);
         int len = urb->transfer_buffer_length;
-        dma_addr_t data = urb->transfer_dma;
+        int this_sg_len;
+        dma_addr_t data;
         __le32 *plink;
         struct urb_priv *urbp = urb->hcpriv;
         unsigned int toggle;
+        struct scatterlist  *sg;
+        int i;
 
         if (len < 0)
                 return -EINVAL;
@@ -937,12 +940,26 @@ static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
         if (usb_pipein(urb->pipe))
                 status |= TD_CTRL_SPD;
 
+        i = urb->num_sgs;
+        if (len > 0 && i > 0) {
+                sg = urb->sg;
+                data = sg_dma_address(sg);
+
+                /* urb->transfer_buffer_length may be smaller than the
+                 * size of the scatterlist (or vice versa)
+                 */
+                this_sg_len = min_t(int, sg_dma_len(sg), len);
+        } else {
+                sg = NULL;
+                data = urb->transfer_dma;
+                this_sg_len = len;
+        }
         /*
          * Build the DATA TDs
          */
         plink = NULL;
         td = qh->dummy_td;
-        do {    /* Allow zero length packets */
+        for (;;) {      /* Allow zero length packets */
                 int pktsze = maxsze;
 
                 if (len <= pktsze) {            /* The last packet */
@@ -965,10 +982,18 @@ static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
                 plink = &td->link;
                 status |= TD_CTRL_ACTIVE;
 
+                toggle ^= 1;
                 data += pktsze;
+                this_sg_len -= pktsze;
                 len -= maxsze;
-                toggle ^= 1;
-        } while (len > 0);
+                if (this_sg_len <= 0) {
+                        if (--i <= 0 || len <= 0)
+                                break;
+                        sg = sg_next(sg);
+                        data = sg_dma_address(sg);
+                        this_sg_len = min_t(int, sg_dma_len(sg), len);
+                }
+        }
 
         /*
          * URB_ZERO_PACKET means adding a 0-length packet, if direction