usb: dwc2: Add SPLIT INTERRUPT transaction support

CSPLITs for INTERRUPT transactions have to be scheduled in each microframe
following the SSPLIT. INTERRUPT transfers are executed in the next even/
odd microframe depending on the HCCHAR_ODDFRM flag.

As there are no handshakes for INTERRUPT SSPLITs the SSPLIT may have
failed (transport error) without the error being detected by the host
driver. If the last CSPLIT is not received within 4 microframes after the
SSPLIT there was a transaction error and the complete transaction has
to be restarted.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>

2 files changed, 24 insertions, 5 deletions

diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index 413845cdc2..291e4a5f57 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -776,7 +776,7 @@ static int dwc2_eptype[] = {
 
 static int transfer_chunk(struct dwc2_hc_regs *hc_regs, void *aligned_buffer,
 			  int *pid, int in, void *buffer, int num_packets,
-			  int xfer_len, int *actual_len)
+			  int xfer_len, int *actual_len, int odd_frame)
 {
 	int ret = 0;
 	uint32_t sub;
@@ -804,8 +804,10 @@ static int transfer_chunk(struct dwc2_hc_regs *hc_regs, void *aligned_buffer,
 
 	/* Set host channel enable after all other setup is complete. */
 	clrsetbits_le32(&hc_regs->hcchar, DWC2_HCCHAR_MULTICNT_MASK |
-			DWC2_HCCHAR_CHEN | DWC2_HCCHAR_CHDIS,
+			DWC2_HCCHAR_CHEN | DWC2_HCCHAR_CHDIS |
+			DWC2_HCCHAR_ODDFRM,
 			(1 << DWC2_HCCHAR_MULTICNT_OFFSET) |
+			(odd_frame << DWC2_HCCHAR_ODDFRM_OFFSET) |
 			DWC2_HCCHAR_CHEN);
 
 	ret = wait_for_chhltd(hc_regs, &sub, pid);
@@ -831,6 +833,7 @@ int chunk_msg(struct dwc2_priv *priv, struct usb_device *dev,
 {
 	struct dwc2_core_regs *regs = priv->regs;
 	struct dwc2_hc_regs *hc_regs = &regs->hc_regs[DWC2_HC_CHANNEL];
+	struct dwc2_host_regs *host_regs = &regs->host_regs;
 	int devnum = usb_pipedevice(pipe);
 	int ep = usb_pipeendpoint(pipe);
 	int max = usb_maxpacket(dev, pipe);
@@ -843,6 +846,7 @@ int chunk_msg(struct dwc2_priv *priv, struct usb_device *dev,
 	uint32_t num_packets;
 	int stop_transfer = 0;
 	uint32_t max_xfer_len;
+	int ssplit_frame_num = 0;
 
 	debug("%s: msg: pipe %lx pid %d in %d len %d\n", __func__, pipe, *pid,
 	      in, len);
@@ -881,6 +885,7 @@ int chunk_msg(struct dwc2_priv *priv, struct usb_device *dev,
 	do {
 		int actual_len = 0;
 		uint32_t hcint;
+		int odd_frame = 0;
 		xfer_len = len - done;
 
 		if (xfer_len > max_xfer_len)
@@ -895,19 +900,32 @@ int chunk_msg(struct dwc2_priv *priv, struct usb_device *dev,
 		else if (do_split)
 			clrbits_le32(&hc_regs->hcsplt, DWC2_HCSPLT_COMPSPLT);
 
+		if (eptype == DWC2_HCCHAR_EPTYPE_INTR) {
+			int uframe_num = readl(&host_regs->hfnum);
+			if (!(uframe_num & 0x1))
+				odd_frame = 1;
+		}
+
 		ret = transfer_chunk(hc_regs, priv->aligned_buffer, pid,
 				     in, (char *)buffer + done, num_packets,
-				     xfer_len, &actual_len);
+				     xfer_len, &actual_len, odd_frame);
 
 		hcint = readl(&hc_regs->hcint);
 		if (complete_split) {
 			stop_transfer = 0;
-			if (hcint & DWC2_HCINT_NYET)
+			if (hcint & DWC2_HCINT_NYET) {
 				ret = 0;
-			else
+				int frame_num = DWC2_HFNUM_MAX_FRNUM &
+						readl(&host_regs->hfnum);
+				if (((frame_num - ssplit_frame_num) &
+				    DWC2_HFNUM_MAX_FRNUM) > 4)
+					ret = -EAGAIN;
+			} else
 				complete_split = 0;
 		} else if (do_split) {
 			if (hcint & DWC2_HCINT_ACK) {
+				ssplit_frame_num = DWC2_HFNUM_MAX_FRNUM &
+						   readl(&host_regs->hfnum);
 				ret = 0;
 				complete_split = 1;
 			}
diff --git a/drivers/usb/host/dwc2.h b/drivers/usb/host/dwc2.h
index f69372e6b4..594757b609 100644
--- a/drivers/usb/host/dwc2.h
+++ b/drivers/usb/host/dwc2.h
@@ -500,6 +500,7 @@ struct dwc2_core_regs {
 #define DWC2_HFNUM_FRNUM_OFFSET				0
 #define DWC2_HFNUM_FRREM_MASK				(0xFFFF << 16)
 #define DWC2_HFNUM_FRREM_OFFSET				16
+#define DWC2_HFNUM_MAX_FRNUM				0x3FFF
 #define DWC2_HPTXSTS_PTXFSPCAVAIL_MASK			(0xFFFF << 0)
 #define DWC2_HPTXSTS_PTXFSPCAVAIL_OFFSET		0
 #define DWC2_HPTXSTS_PTXQSPCAVAIL_MASK			(0xFF << 16)