[PATCH 2/2] usb/dummy_hcd: add sg support

[Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>]

This patch adds sg support to dummy_hcd. It seems that uas is not able
to work with a hcd which does not support sg only based transfers.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 drivers/usb/gadget/dummy_hcd.c |   80 ++++++++++++++++++++++++++++++++++++---
 1 files changed, 73 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/dummy_hcd.c b/drivers/usb/gadget/dummy_hcd.c
index 670ee24..92c04f6 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -39,6 +39,7 @@
 #include <linux/usb.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb/hcd.h>
+#include <linux/scatterlist.h>
 
 #include <asm/byteorder.h>
 #include <asm/io.h>
@@ -1078,9 +1079,10 @@ static int dummy_urb_enqueue (
 	unsigned long	flags;
 	int		rc;
 
-	if (!urb->transfer_buffer && urb->transfer_buffer_length)
-		return -EINVAL;
-
+	if (!urb->transfer_buffer && urb->transfer_buffer_length) {
+			if (!urb->num_sgs)
+				return -EINVAL;
+	}
 	urbp = kmalloc (sizeof *urbp, mem_flags);
 	if (!urbp)
 		return -ENOMEM;
@@ -1139,16 +1141,79 @@ static int dummy_perform_transfer(struct urb *urb, struct dummy_request *req,
 {
 	void *ubuf, *rbuf;
 	int to_host;
+	struct sg_mapping_iter miter;
+	u32 flags = SG_MITER_ATOMIC;
+	u32 done = 0;
+	u32 skip = 0;
+	u32 trans = 0;
 
 	to_host = usb_pipein(urb->pipe);
 	rbuf = req->req.buf + req->req.actual;
-	ubuf = urb->transfer_buffer += urb->actual_length;
+
+	if (!urb->num_sgs) {
+		ubuf = urb->transfer_buffer += urb->actual_length;
+		if (to_host)
+			memcpy(ubuf, rbuf, len);
+		else
+			memcpy(rbuf, ubuf, len);
+		return len;
+	}
 
 	if (to_host)
-		memcpy(ubuf, rbuf, len);
+		flags |= SG_MITER_TO_SG;
 	else
-		memcpy(rbuf, ubuf, len);
-	return len;
+		flags |= SG_MITER_FROM_SG;
+
+	sg_miter_start(&miter, urb->sg, urb->num_sgs,
+			flags);
+
+	BUG_ON(!sg_miter_next(&miter));
+	if (urb->actual_length) {
+		do {
+			u32 old_done = done;
+
+			done += miter.length;
+			if (urb->actual_length > done) {
+				sg_miter_next(&miter);
+				continue;
+			}
+			if (urb->actual_length == done) {
+
+				skip = done - old_done;
+				if (skip < miter.length)
+					break;
+				skip = 0;
+				sg_miter_next(&miter);
+				break;
+			}
+
+			done -= miter.length;
+			skip = urb->actual_length - done;
+			break;
+		} while (1);
+	}
+	do {
+		u32 this_sg;
+
+		ubuf = miter.addr + skip;
+		rbuf += skip;
+		this_sg = min(len, miter.length - skip);
+		trans += this_sg;
+
+		if (to_host)
+			memcpy(ubuf, rbuf, this_sg);
+		else
+			memcpy(rbuf, ubuf, this_sg);
+		len -= this_sg;
+
+		if (!len)
+			break;
+		BUG_ON(!sg_miter_next(&miter));
+		skip = 0;
+	} while (1);
+
+	sg_miter_stop(&miter);
+	return trans;
 }
 
 /* transfer up to a frame's worth; caller must own lock */
@@ -2213,6 +2278,7 @@ static int dummy_h_get_frame (struct usb_hcd *hcd)
 
 static int dummy_setup(struct usb_hcd *hcd)
 {
+	hcd->self.sg_tablesize = ~0;
 	if (usb_hcd_is_primary_hcd(hcd)) {
 		the_controller.hs_hcd = hcd_to_dummy_hcd(hcd);
 		the_controller.hs_hcd->dum = &the_controller;
-- 
1.7.7.1

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