usb: dwc2: host: Get aligned DMA in a more supported way

All other host controllers who want aligned buffers for DMA do it a
certain way.  Let's do that too instead of working behind the USB core's
back.  This makes our interrupt handler not take forever and also rips
out a lot of code, simplifying things a bunch.

This also has the side effect of removing the 65535 max transfer size
limit.

NOTE: The actual code to allocate the aligned buffers is ripped almost
completely from the tegra EHCI driver.  At some point in the future we
may want to add this functionality to the USB core to share more code
everywhere.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: John Youn <johnyoun@synopsys.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

1 files changed, 83 insertions, 87 deletions

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 8847c72e55f6..bc4bdbc1534e 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -635,9 +635,9 @@ static void dwc2_hc_init_split(struct dwc2_hsotg *hsotg,
 	chan->hub_port = (u8)hub_port;
 }
 
-static void *dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
-			       struct dwc2_host_chan *chan,
-			       struct dwc2_qtd *qtd, void *bufptr)
+static void dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
+			      struct dwc2_host_chan *chan,
+			      struct dwc2_qtd *qtd)
 {
 	struct dwc2_hcd_urb *urb = qtd->urb;
 	struct dwc2_hcd_iso_packet_desc *frame_desc;
@@ -657,7 +657,6 @@ static void *dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
 			else
 				chan->xfer_buf = urb->setup_packet;
 			chan->xfer_len = 8;
-			bufptr = NULL;
 			break;
 
 		case DWC2_CONTROL_DATA:
@@ -684,7 +683,6 @@ static void *dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
 				chan->xfer_dma = hsotg->status_buf_dma;
 			else
 				chan->xfer_buf = hsotg->status_buf;
-			bufptr = NULL;
 			break;
 		}
 		break;
@@ -717,14 +715,6 @@ static void *dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
 
 		chan->xfer_len = frame_desc->length - qtd->isoc_split_offset;
 
-		/* For non-dword aligned buffers */
-		if (hsotg->core_params->dma_enable > 0 &&
-		    (chan->xfer_dma & 0x3))
-			bufptr = (u8 *)urb->buf + frame_desc->offset +
-					qtd->isoc_split_offset;
-		else
-			bufptr = NULL;
-
 		if (chan->xact_pos == DWC2_HCSPLT_XACTPOS_ALL) {
 			if (chan->xfer_len <= 188)
 				chan->xact_pos = DWC2_HCSPLT_XACTPOS_ALL;
@@ -733,63 +723,93 @@ static void *dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
 		}
 		break;
 	}
+}
+
+#define DWC2_USB_DMA_ALIGN 4
+
+struct dma_aligned_buffer {
+	void *kmalloc_ptr;
+	void *old_xfer_buffer;
+	u8 data[0];
+};
+
+static void dwc2_free_dma_aligned_buffer(struct urb *urb)
+{
+	struct dma_aligned_buffer *temp;
+
+	if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
+		return;
+
+	temp = container_of(urb->transfer_buffer,
+		struct dma_aligned_buffer, data);
 
-	return bufptr;
+	if (usb_urb_dir_in(urb))
+		memcpy(temp->old_xfer_buffer, temp->data,
+		       urb->transfer_buffer_length);
+	urb->transfer_buffer = temp->old_xfer_buffer;
+	kfree(temp->kmalloc_ptr);
+
+	urb->transfer_flags &= ~URB_ALIGNED_TEMP_BUFFER;
 }
 
-static int dwc2_hc_setup_align_buf(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
-				   struct dwc2_host_chan *chan,
-				   struct dwc2_hcd_urb *urb, void *bufptr)
+static int dwc2_alloc_dma_aligned_buffer(struct urb *urb, gfp_t mem_flags)
 {
-	u32 buf_size;
-	struct urb *usb_urb;
-	struct usb_hcd *hcd;
+	struct dma_aligned_buffer *temp, *kmalloc_ptr;
+	size_t kmalloc_size;
 
-	if (!qh->dw_align_buf) {
-		if (chan->ep_type != USB_ENDPOINT_XFER_ISOC)
-			buf_size = hsotg->core_params->max_transfer_size;
-		else
-			/* 3072 = 3 max-size Isoc packets */
-			buf_size = 3072;
+	if (urb->num_sgs || urb->sg ||
+	    urb->transfer_buffer_length == 0 ||
+	    !((uintptr_t)urb->transfer_buffer & (DWC2_USB_DMA_ALIGN - 1)))
+		return 0;
 
-		qh->dw_align_buf = kmalloc(buf_size, GFP_ATOMIC | GFP_DMA);
-		if (!qh->dw_align_buf)
-			return -ENOMEM;
-		qh->dw_align_buf_size = buf_size;
-	}
+	/* Allocate a buffer with enough padding for alignment */
+	kmalloc_size = urb->transfer_buffer_length +
+		sizeof(struct dma_aligned_buffer) + DWC2_USB_DMA_ALIGN - 1;
 
-	if (chan->xfer_len) {
-		dev_vdbg(hsotg->dev, "%s(): non-aligned buffer\n", __func__);
-		usb_urb = urb->priv;
+	kmalloc_ptr = kmalloc(kmalloc_size, mem_flags);
+	if (!kmalloc_ptr)
+		return -ENOMEM;
 
-		if (usb_urb) {
-			if (usb_urb->transfer_flags &
-			    (URB_SETUP_MAP_SINGLE | URB_DMA_MAP_SG |
-			     URB_DMA_MAP_PAGE | URB_DMA_MAP_SINGLE)) {
-				hcd = dwc2_hsotg_to_hcd(hsotg);
-				usb_hcd_unmap_urb_for_dma(hcd, usb_urb);
-			}
-			if (!chan->ep_is_in)
-				memcpy(qh->dw_align_buf, bufptr,
-				       chan->xfer_len);
-		} else {
-			dev_warn(hsotg->dev, "no URB in dwc2_urb\n");
-		}
-	}
+	/* Position our struct dma_aligned_buffer such that data is aligned */
+	temp = PTR_ALIGN(kmalloc_ptr + 1, DWC2_USB_DMA_ALIGN) - 1;
+	temp->kmalloc_ptr = kmalloc_ptr;
+	temp->old_xfer_buffer = urb->transfer_buffer;
+	if (usb_urb_dir_out(urb))
+		memcpy(temp->data, urb->transfer_buffer,
+		       urb->transfer_buffer_length);
+	urb->transfer_buffer = temp->data;
 
-	qh->dw_align_buf_dma = dma_map_single(hsotg->dev,
-			qh->dw_align_buf, qh->dw_align_buf_size,
-			chan->ep_is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
-	if (dma_mapping_error(hsotg->dev, qh->dw_align_buf_dma)) {
-		dev_err(hsotg->dev, "can't map align_buf\n");
-		chan->align_buf = 0;
-		return -EINVAL;
-	}
+	urb->transfer_flags |= URB_ALIGNED_TEMP_BUFFER;
 
-	chan->align_buf = qh->dw_align_buf_dma;
 	return 0;
 }
 
+static int dwc2_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
+				      gfp_t mem_flags)
+{
+	int ret;
+
+	/* We assume setup_dma is always aligned; warn if not */
+	WARN_ON_ONCE(urb->setup_dma &&
+		     (urb->setup_dma & (DWC2_USB_DMA_ALIGN - 1)));
+
+	ret = dwc2_alloc_dma_aligned_buffer(urb, mem_flags);
+	if (ret)
+		return ret;
+
+	ret = usb_hcd_map_urb_for_dma(hcd, urb, mem_flags);
+	if (ret)
+		dwc2_free_dma_aligned_buffer(urb);
+
+	return ret;
+}
+
+static void dwc2_unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
+{
+	usb_hcd_unmap_urb_for_dma(hcd, urb);
+	dwc2_free_dma_aligned_buffer(urb);
+}
+
 /**
  * dwc2_assign_and_init_hc() - Assigns transactions from a QTD to a free host
  * channel and initializes the host channel to perform the transactions. The
@@ -804,7 +824,6 @@ static int dwc2_assign_and_init_hc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 	struct dwc2_host_chan *chan;
 	struct dwc2_hcd_urb *urb;
 	struct dwc2_qtd *qtd;
-	void *bufptr = NULL;
 
 	if (dbg_qh(qh))
 		dev_vdbg(hsotg->dev, "%s(%p,%p)\n", __func__, hsotg, qh);
@@ -866,16 +885,10 @@ static int dwc2_assign_and_init_hc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 		!dwc2_hcd_is_pipe_in(&urb->pipe_info))
 		urb->actual_length = urb->length;
 
-	if (hsotg->core_params->dma_enable > 0) {
+	if (hsotg->core_params->dma_enable > 0)
 		chan->xfer_dma = urb->dma + urb->actual_length;
-
-		/* For non-dword aligned case */
-		if (hsotg->core_params->dma_desc_enable <= 0 &&
-		    (chan->xfer_dma & 0x3))
-			bufptr = (u8 *)urb->buf + urb->actual_length;
-	} else {
+	else
 		chan->xfer_buf = (u8 *)urb->buf + urb->actual_length;
-	}
 
 	chan->xfer_len = urb->length - urb->actual_length;
 	chan->xfer_count = 0;
@@ -887,27 +900,7 @@ static int dwc2_assign_and_init_hc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 		chan->do_split = 0;
 
 	/* Set the transfer attributes */
-	bufptr = dwc2_hc_init_xfer(hsotg, chan, qtd, bufptr);
-
-	/* Non DWORD-aligned buffer case */
-	if (bufptr) {
-		dev_vdbg(hsotg->dev, "Non-aligned buffer\n");
-		if (dwc2_hc_setup_align_buf(hsotg, qh, chan, urb, bufptr)) {
-			dev_err(hsotg->dev,
-				"%s: Failed to allocate memory to handle non-dword aligned buffer\n",
-				__func__);
-			/* Add channel back to free list */
-			chan->align_buf = 0;
-			chan->multi_count = 0;
-			list_add_tail(&chan->hc_list_entry,
-				      &hsotg->free_hc_list);
-			qtd->in_process = 0;
-			qh->channel = NULL;
-			return -ENOMEM;
-		}
-	} else {
-		chan->align_buf = 0;
-	}
+	dwc2_hc_init_xfer(hsotg, chan, qtd);
 
 	if (chan->ep_type == USB_ENDPOINT_XFER_INT ||
 	    chan->ep_type == USB_ENDPOINT_XFER_ISOC)
@@ -2971,6 +2964,9 @@ static struct hc_driver dwc2_hc_driver = {
 
 	.bus_suspend = _dwc2_hcd_suspend,
 	.bus_resume = _dwc2_hcd_resume,
+
+	.map_urb_for_dma	= dwc2_map_urb_for_dma,
+	.unmap_urb_for_dma	= dwc2_unmap_urb_for_dma,
 };
 
 /*