From: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
This patch adds support for transferring requests, which are
non-contiguous in physical memory, i.e. the data buffer is described by
a scatter-list. This allows transferring large requests without relying
on error-prone contiguous buffer allocations. This way of allocating
requests is already implemented in functionfs and TCM USB functions and
automatically used if UDC driver advertises scatter-gather suppport.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
[mszyprow: fixed null pointer issue, rewrote commit message]
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
Andrzej no longer works at Samsung, so I decided to continue this work.
Here are some implementation details, which helps to understand the
proposed changes.
Non-isochronous transfers:
The code for filling a single DDMA entry is extracted from
dwc2_gadget_config_nonisoc_xfer_ddma() as
dwc2_gadget_fill_nonisoc_xfer_ddma_one() function. The original function
now either calls the extracted code (in case of physically contiguous
request buffer) or iterates over scatterlist elements, for each of them
calling the mentioned code.
Isochronous transfers:
If the usb request contains a scatterlist, the address from the first
element is used as dma address at dwc2_gadget_fill_isoc_desc() invocations.
Current code for isoc transfers does not allow more than 4096 bytes per
transfer, so it is assumed there is only one element in the scatterlist.
If there are more, a warning is issued. Please see the fragment under
the comment:
/* In DDMA mode for ISOC's don't queue request if length greater
* than descriptor limits.
*/
in dwc2_hsotg_ep_queue() to see the limits for isoc transfers.
---
Changelog:
v2..v3:
- fixed null pointer issue when processing ep0 zlp
- renamed _dwc2_gadget_config_nonisoc_xfer_ddma() to
dwc2_gadget_fill_nonisoc_xfer_ddma_one()
- rewrote commit message to explain the reason for
the proposed changes
v1..v2:
- using_desc_dma() called to check if DDMA available
---
drivers/usb/dwc2/gadget.c | 113 ++++++++++++++++++++++++++------------
1 file changed, 77 insertions(+), 36 deletions(-)
diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 357beb40b7a3..af419034e438 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -835,22 +835,13 @@ static u32 dwc2_gadget_get_desc_params(struct dwc2_hsotg_ep *hs_ep, u32 *mask)
return desc_size;
}
-/*
- * dwc2_gadget_config_nonisoc_xfer_ddma - prepare non ISOC DMA desc chain.
- * @hs_ep: The endpoint
- * @dma_buff: DMA address to use
- * @len: Length of the transfer
- *
- * This function will iterate over descriptor chain and fill its entries
- * with corresponding information based on transfer data.
- */
-static void dwc2_gadget_config_nonisoc_xfer_ddma(struct dwc2_hsotg_ep *hs_ep,
+static void dwc2_gadget_fill_nonisoc_xfer_ddma_one(struct dwc2_hsotg_ep *hs_ep,
+ struct dwc2_dma_desc **desc,
dma_addr_t dma_buff,
- unsigned int len)
+ unsigned int len,
+ bool true_last)
{
- struct dwc2_hsotg *hsotg = hs_ep->parent;
int dir_in = hs_ep->dir_in;
- struct dwc2_dma_desc *desc = hs_ep->desc_list;
u32 mps = hs_ep->ep.maxpacket;
u32 maxsize = 0;
u32 offset = 0;
@@ -865,39 +856,77 @@ static void dwc2_gadget_config_nonisoc_xfer_ddma(struct dwc2_hsotg_ep *hs_ep,
hs_ep->desc_count = 1;
for (i = 0; i < hs_ep->desc_count; ++i) {
- desc->status = 0;
- desc->status |= (DEV_DMA_BUFF_STS_HBUSY
+ (*desc)->status = 0;
+ (*desc)->status |= (DEV_DMA_BUFF_STS_HBUSY
<< DEV_DMA_BUFF_STS_SHIFT);
if (len > maxsize) {
if (!hs_ep->index && !dir_in)
- desc->status |= (DEV_DMA_L | DEV_DMA_IOC);
+ (*desc)->status |= (DEV_DMA_L | DEV_DMA_IOC);
- desc->status |= (maxsize <<
- DEV_DMA_NBYTES_SHIFT & mask);
- desc->buf = dma_buff + offset;
+ (*desc)->status |=
+ maxsize << DEV_DMA_NBYTES_SHIFT & mask;
+ (*desc)->buf = dma_buff + offset;
len -= maxsize;
offset += maxsize;
} else {
- desc->status |= (DEV_DMA_L | DEV_DMA_IOC);
+ if (true_last)
+ (*desc)->status |= (DEV_DMA_L | DEV_DMA_IOC);
if (dir_in)
- desc->status |= (len % mps) ? DEV_DMA_SHORT :
- ((hs_ep->send_zlp) ? DEV_DMA_SHORT : 0);
- if (len > maxsize)
- dev_err(hsotg->dev, "wrong len %d\n", len);
+ (*desc)->status |= (len % mps) ? DEV_DMA_SHORT :
+ ((hs_ep->send_zlp && true_last) ?
+ DEV_DMA_SHORT : 0);
- desc->status |=
+ (*desc)->status |=
len << DEV_DMA_NBYTES_SHIFT & mask;
- desc->buf = dma_buff + offset;
+ (*desc)->buf = dma_buff + offset;
}
- desc->status &= ~DEV_DMA_BUFF_STS_MASK;
- desc->status |= (DEV_DMA_BUFF_STS_HREADY
+ (*desc)->status &= ~DEV_DMA_BUFF_STS_MASK;
+ (*desc)->status |= (DEV_DMA_BUFF_STS_HREADY
<< DEV_DMA_BUFF_STS_SHIFT);
- desc++;
+ (*desc)++;
+ }
+}
+
+/*
+ * dwc2_gadget_config_nonisoc_xfer_ddma - prepare non ISOC DMA desc chain.
+ * @hs_ep: The endpoint
+ * @ureq: Request to transfer
+ * @offset: offset in bytes
+ * @len: Length of the transfer
+ *
+ * This function will iterate over descriptor chain and fill its entries
+ * with corresponding information based on transfer data.
+ */
+static void dwc2_gadget_config_nonisoc_xfer_ddma(struct dwc2_hsotg_ep *hs_ep,
+ struct usb_request *ureq,
+ unsigned int offset,
+ unsigned int len)
+{
+ struct dwc2_dma_desc *desc = hs_ep->desc_list;
+ struct scatterlist *sg;
+ int i;
+ u8 desc_count = 0;
+
+ /* non-DMA sg buffer */
+ if (!ureq->num_sgs) {
+ dwc2_gadget_fill_nonisoc_xfer_ddma_one(hs_ep, &desc,
+ ureq->dma + offset, len, true);
+ return;
}
+
+ /* DMA sg buffer */
+ for_each_sg(ureq->sg, sg, ureq->num_sgs, i) {
+ dwc2_gadget_fill_nonisoc_xfer_ddma_one(hs_ep, &desc,
+ sg_dma_address(sg) + sg->offset, sg_dma_len(sg),
+ sg_is_last(sg));
+ desc_count += hs_ep->desc_count;
+ }
+
+ hs_ep->desc_count = desc_count;
}
/*
@@ -1011,7 +1040,13 @@ static void dwc2_gadget_start_isoc_ddma(struct dwc2_hsotg_ep *hs_ep)
hs_ep->next_desc = 0;
list_for_each_entry_safe(hs_req, treq, &hs_ep->queue, queue) {
- ret = dwc2_gadget_fill_isoc_desc(hs_ep, hs_req->req.dma,
+ dma_addr_t dma_addr = hs_req->req.dma;
+
+ if (hs_req->req.num_sgs) {
+ WARN_ON(hs_req->req.num_sgs > 1);
+ dma_addr = sg_dma_address(hs_req->req.sg);
+ }
+ ret = dwc2_gadget_fill_isoc_desc(hs_ep, dma_addr,
hs_req->req.length);
if (ret)
break;
@@ -1167,7 +1202,7 @@ static void dwc2_hsotg_start_req(struct dwc2_hsotg *hsotg,
offset = ureq->actual;
/* Fill DDMA chain entries */
- dwc2_gadget_config_nonisoc_xfer_ddma(hs_ep, ureq->dma + offset,
+ dwc2_gadget_config_nonisoc_xfer_ddma(hs_ep, ureq, offset,
length);
/* write descriptor chain address to control register */
@@ -1466,7 +1501,13 @@ static int dwc2_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
*/
if (using_desc_dma(hs) && hs_ep->isochronous) {
if (hs_ep->target_frame != TARGET_FRAME_INITIAL) {
- dwc2_gadget_fill_isoc_desc(hs_ep, hs_req->req.dma,
+ dma_addr_t dma_addr = hs_req->req.dma;
+
+ if (hs_req->req.num_sgs) {
+ WARN_ON(hs_req->req.num_sgs > 1);
+ dma_addr = sg_dma_address(hs_req->req.sg);
+ }
+ dwc2_gadget_fill_isoc_desc(hs_ep, dma_addr,
hs_req->req.length);
}
return 0;
@@ -2054,13 +2095,12 @@ static void dwc2_hsotg_program_zlp(struct dwc2_hsotg *hsotg,
dev_dbg(hsotg->dev, "Receiving zero-length packet on ep%d\n",
index);
if (using_desc_dma(hsotg)) {
- /* Not specific buffer needed for ep0 ZLP */
- dma_addr_t dma = hs_ep->desc_list_dma;
-
if (!index)
dwc2_gadget_set_ep0_desc_chain(hsotg, hs_ep);
- dwc2_gadget_config_nonisoc_xfer_ddma(hs_ep, dma, 0);
+ /* Not specific buffer needed for ep0 ZLP */
+ dwc2_gadget_fill_nonisoc_xfer_ddma_one(hs_ep, &hs_ep->desc_list,
+ hs_ep->desc_list_dma, 0, true);
} else {
dwc2_writel(hsotg, DXEPTSIZ_MC(1) | DXEPTSIZ_PKTCNT(1) |
DXEPTSIZ_XFERSIZE(0),
@@ -4471,6 +4511,7 @@ static int dwc2_hsotg_udc_start(struct usb_gadget *gadget,
hsotg->enabled = 0;
spin_unlock_irqrestore(&hsotg->lock, flags);
+ gadget->sg_supported = using_desc_dma(hsotg);
dev_info(hsotg->dev, "bound driver %s\n", driver->driver.name);
return 0;
--
2.17.1
