usb: dwc2: gadget: Start and complete DDMA isoc transfers

For DDMA mode in case of isochronous transfers completion performed
differently than other transfer types. This is because each usb request
was mapped to one descriptor in the chain and SW gets xfercomplete
interrupt on all descriptors. The endpoint remains enabled until HW
processes last descriptor with "L" bit set or BNA interrupt gets
asserted for IN and OUT endpoints correspondingly.

Add function dwc2_gadget_complete_isoc_request_ddma() - completes one
isochronous request taken from endpoint's queue.

Add function dwc2_gadget_start_next_isoc_ddma() - tries to restart
isochronous endpoint if requests are pending. Check for EPENA. If the
endpoint was disabled, try to restart it after programming descriptor
chain prepared by SW earlier, switch SW to fill the other half of chain.

Add function dwc2_gadget_fill_isoc_desc() - initializes DMA descriptor
for isochronous transfer based on the received request data and endpoint
characteristics.

Added function dwc2_gadget_start_isoc_ddma() - prepare DMA chain for
isochronous transfer in DDMA, programs corresponding DMA address to
DEPDMA, enables the endpoint. This function is called once SW decides to
start isochronous IN or OUT transfer depend on reception of NAK or
OUTTknEPdis interrupts indicating first isochronous token arrival from
host.
Signed-off-by: Vahram Aharonyan <vahrama@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc2/gadget.c

@@ -735,6 +735,139 @@ static void dwc2_gadget_config_nonisoc_xfer_ddma(struct dwc2_hsotg_ep *hs_ep,
 	}
 }
 
+/*
+ * dwc2_gadget_fill_isoc_desc - fills next isochronous descriptor in chain.
+ * @hs_ep: The isochronous endpoint.
+ * @dma_buff: usb requests dma buffer.
+ * @len: usb request transfer length.
+ *
+ * Finds out index of first free entry either in the bottom or up half of
+ * descriptor chain depend on which is under SW control and not processed
+ * by HW. Then fills that descriptor with the data of the arrived usb request,
+ * frame info, sets Last and IOC bits increments next_desc. If filled
+ * descriptor is not the first one, removes L bit from the previous descriptor
+ * status.
+ */
+static int dwc2_gadget_fill_isoc_desc(struct dwc2_hsotg_ep *hs_ep,
+				      dma_addr_t dma_buff, unsigned int len)
+{
+	struct dwc2_dma_desc *desc;
+	struct dwc2_hsotg *hsotg = hs_ep->parent;
+	u32 index;
+	u32 maxsize = 0;
+	u32 mask = 0;
+
+	maxsize = dwc2_gadget_get_desc_params(hs_ep, &mask);
+	if (len > maxsize) {
+		dev_err(hsotg->dev, "wrong len %d\n", len);
+		return -EINVAL;
+	}
+
+	/*
+	 * If SW has already filled half of chain, then return and wait for
+	 * the other chain to be processed by HW.
+	 */
+	if (hs_ep->next_desc == MAX_DMA_DESC_NUM_GENERIC / 2)
+		return -EBUSY;
+
+	/* Increment frame number by interval for IN */
+	if (hs_ep->dir_in)
+		dwc2_gadget_incr_frame_num(hs_ep);
+
+	index = (MAX_DMA_DESC_NUM_GENERIC / 2) * hs_ep->isoc_chain_num +
+		 hs_ep->next_desc;
+
+	/* Sanity check of calculated index */
+	if ((hs_ep->isoc_chain_num && index > MAX_DMA_DESC_NUM_GENERIC) ||
+	    (!hs_ep->isoc_chain_num && index > MAX_DMA_DESC_NUM_GENERIC / 2)) {
+		dev_err(hsotg->dev, "wrong index %d for iso chain\n", index);
+		return -EINVAL;
+	}
+
+	desc = &hs_ep->desc_list[index];
+
+	/* Clear L bit of previous desc if more than one entries in the chain */
+	if (hs_ep->next_desc)
+		hs_ep->desc_list[index - 1].status &= ~DEV_DMA_L;
+
+	dev_dbg(hsotg->dev, "%s: Filling ep %d, dir %s isoc desc # %d\n",
+		__func__, hs_ep->index, hs_ep->dir_in ? "in" : "out", index);
+
+	desc->status = 0;
+	desc->status |= (DEV_DMA_BUFF_STS_HBUSY	<< DEV_DMA_BUFF_STS_SHIFT);
+
+	desc->buf = dma_buff;
+	desc->status |= (DEV_DMA_L | DEV_DMA_IOC |
+			 ((len << DEV_DMA_NBYTES_SHIFT) & mask));
+
+	if (hs_ep->dir_in) {
+		desc->status |= ((hs_ep->mc << DEV_DMA_ISOC_PID_SHIFT) &
+				 DEV_DMA_ISOC_PID_MASK) |
+				((len % hs_ep->ep.maxpacket) ?
+				 DEV_DMA_SHORT : 0) |
+				((hs_ep->target_frame <<
+				  DEV_DMA_ISOC_FRNUM_SHIFT) &
+				 DEV_DMA_ISOC_FRNUM_MASK);
+	}
+
+	desc->status &= ~DEV_DMA_BUFF_STS_MASK;
+	desc->status |= (DEV_DMA_BUFF_STS_HREADY << DEV_DMA_BUFF_STS_SHIFT);
+
+	/* Update index of last configured entry in the chain */
+	hs_ep->next_desc++;
+
+	return 0;
+}
+
+/*
+ * dwc2_gadget_start_isoc_ddma - start isochronous transfer in DDMA
+ * @hs_ep: The isochronous endpoint.
+ *
+ * Prepare first descriptor chain for isochronous endpoints. Afterwards
+ * write DMA address to HW and enable the endpoint.
+ *
+ * Switch between descriptor chains via isoc_chain_num to give SW opportunity
+ * to prepare second descriptor chain while first one is being processed by HW.
+ */
+static void dwc2_gadget_start_isoc_ddma(struct dwc2_hsotg_ep *hs_ep)
+{
+	struct dwc2_hsotg *hsotg = hs_ep->parent;
+	struct dwc2_hsotg_req *hs_req, *treq;
+	int index = hs_ep->index;
+	int ret;
+	u32 dma_reg;
+	u32 depctl;
+	u32 ctrl;
+
+	if (list_empty(&hs_ep->queue)) {
+		dev_dbg(hsotg->dev, "%s: No requests in queue\n", __func__);
+		return;
+	}
+
+	list_for_each_entry_safe(hs_req, treq, &hs_ep->queue, queue) {
+		ret = dwc2_gadget_fill_isoc_desc(hs_ep, hs_req->req.dma,
+						 hs_req->req.length);
+		if (ret) {
+			dev_dbg(hsotg->dev, "%s: desc chain full\n", __func__);
+			break;
+		}
+	}
+
+	depctl = hs_ep->dir_in ? DIEPCTL(index) : DOEPCTL(index);
+	dma_reg = hs_ep->dir_in ? DIEPDMA(index) : DOEPDMA(index);
+
+	/* write descriptor chain address to control register */
+	dwc2_writel(hs_ep->desc_list_dma, hsotg->regs + dma_reg);
+
+	ctrl = dwc2_readl(hsotg->regs + depctl);
+	ctrl |= DXEPCTL_EPENA | DXEPCTL_CNAK;
+	dwc2_writel(ctrl, hsotg->regs + depctl);
+
+	/* Switch ISOC descriptor chain number being processed by SW*/
+	hs_ep->isoc_chain_num = (hs_ep->isoc_chain_num ^ 1) & 0x1;
+	hs_ep->next_desc = 0;
+}
+
 /**
  * dwc2_hsotg_start_req - start a USB request from an endpoint's queue
  * @hsotg: The controller state.
@@ -1145,6 +1278,22 @@ static int dwc2_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
 	first = list_empty(&hs_ep->queue);
 	list_add_tail(&hs_req->queue, &hs_ep->queue);
 
+	/*
+	 * Handle DDMA isochronous transfers separately - just add new entry
+	 * to the half of descriptor chain that is not processed by HW.
+	 * Transfer will be started once SW gets either one of NAK or
+	 * OutTknEpDis interrupts.
+	 */
+	if (using_desc_dma(hs) && hs_ep->isochronous &&
+	    hs_ep->target_frame != TARGET_FRAME_INITIAL) {
+		ret = dwc2_gadget_fill_isoc_desc(hs_ep, hs_req->req.dma,
+						 hs_req->req.length);
+		if (ret)
+			dev_dbg(hs->dev, "%s: ISO desc chain full\n", __func__);
+
+		return 0;
+	}
+
 	if (first) {
 		if (!hs_ep->isochronous) {
 			dwc2_hsotg_start_req(hs, hs_ep, hs_req, false);
@@ -1786,6 +1935,10 @@ static void dwc2_hsotg_complete_request(struct dwc2_hsotg *hsotg,
 		spin_lock(&hsotg->lock);
 	}
 
+	/* In DDMA don't need to proceed to starting of next ISOC request */
+	if (using_desc_dma(hsotg) && hs_ep->isochronous)
+		return;
+
 	/*
 	 * Look to see if there is anything else to do. Note, the completion
 	 * of the previous request may have caused a new request to be started
@@ -1797,6 +1950,111 @@ static void dwc2_hsotg_complete_request(struct dwc2_hsotg *hsotg,
 	}
 }
 
+/*
+ * dwc2_gadget_complete_isoc_request_ddma - complete an isoc request in DDMA
+ * @hs_ep: The endpoint the request was on.
+ *
+ * Get first request from the ep queue, determine descriptor on which complete
+ * happened. SW based on isoc_chain_num discovers which half of the descriptor
+ * chain is currently in use by HW, adjusts dma_address and calculates index
+ * of completed descriptor based on the value of DEPDMA register. Update actual
+ * length of request, giveback to gadget.
+ */
+static void dwc2_gadget_complete_isoc_request_ddma(struct dwc2_hsotg_ep *hs_ep)
+{
+	struct dwc2_hsotg *hsotg = hs_ep->parent;
+	struct dwc2_hsotg_req *hs_req;
+	struct usb_request *ureq;
+	int index;
+	dma_addr_t dma_addr;
+	u32 dma_reg;
+	u32 depdma;
+	u32 desc_sts;
+	u32 mask;
+
+	hs_req = get_ep_head(hs_ep);
+	if (!hs_req) {
+		dev_warn(hsotg->dev, "%s: ISOC EP queue empty\n", __func__);
+		return;
+	}
+	ureq = &hs_req->req;
+
+	dma_addr = hs_ep->desc_list_dma;
+
+	/*
+	 * If lower half of  descriptor chain is currently use by SW,
+	 * that means higher half is being processed by HW, so shift
+	 * DMA address to higher half of descriptor chain.
+	 */
+	if (!hs_ep->isoc_chain_num)
+		dma_addr += sizeof(struct dwc2_dma_desc) *
+			    (MAX_DMA_DESC_NUM_GENERIC / 2);
+
+	dma_reg = hs_ep->dir_in ? DIEPDMA(hs_ep->index) : DOEPDMA(hs_ep->index);
+	depdma = dwc2_readl(hsotg->regs + dma_reg);
+
+	index = (depdma - dma_addr) / sizeof(struct dwc2_dma_desc) - 1;
+	desc_sts = hs_ep->desc_list[index].status;
+
+	mask = hs_ep->dir_in ? DEV_DMA_ISOC_TX_NBYTES_MASK :
+	       DEV_DMA_ISOC_RX_NBYTES_MASK;
+	ureq->actual = ureq->length -
+		       ((desc_sts & mask) >> DEV_DMA_ISOC_NBYTES_SHIFT);
+
+	dwc2_hsotg_complete_request(hsotg, hs_ep, hs_req, 0);
+}
+
+/*
+ * dwc2_gadget_start_next_isoc_ddma - start next isoc request, if any.
+ * @hs_ep: The isochronous endpoint to be re-enabled.
+ *
+ * If ep has been disabled due to last descriptor servicing (IN endpoint) or
+ * BNA (OUT endpoint) check the status of other half of descriptor chain that
+ * was under SW control till HW was busy and restart the endpoint if needed.
+ */
+static void dwc2_gadget_start_next_isoc_ddma(struct dwc2_hsotg_ep *hs_ep)
+{
+	struct dwc2_hsotg *hsotg = hs_ep->parent;
+	u32 depctl;
+	u32 dma_reg;
+	u32 ctrl;
+	u32 dma_addr = hs_ep->desc_list_dma;
+	unsigned char index = hs_ep->index;
+
+	dma_reg = hs_ep->dir_in ? DIEPDMA(index) : DOEPDMA(index);
+	depctl = hs_ep->dir_in ? DIEPCTL(index) : DOEPCTL(index);
+
+	ctrl = dwc2_readl(hsotg->regs + depctl);
+
+	/*
+	 * EP was disabled if HW has processed last descriptor or BNA was set.
+	 * So restart ep if SW has prepared new descriptor chain in ep_queue
+	 * routine while HW was busy.
+	 */
+	if (!(ctrl & DXEPCTL_EPENA)) {
+		if (!hs_ep->next_desc) {
+			dev_dbg(hsotg->dev, "%s: No more ISOC requests\n",
+				__func__);
+			return;
+		}
+
+		dma_addr += sizeof(struct dwc2_dma_desc) *
+			    (MAX_DMA_DESC_NUM_GENERIC / 2) *
+			    hs_ep->isoc_chain_num;
+		dwc2_writel(dma_addr, hsotg->regs + dma_reg);
+
+		ctrl |= DXEPCTL_EPENA | DXEPCTL_CNAK;
+		dwc2_writel(ctrl, hsotg->regs + depctl);
+
+		/* Switch ISOC descriptor chain number being processed by SW*/
+		hs_ep->isoc_chain_num = (hs_ep->isoc_chain_num ^ 1) & 0x1;
+		hs_ep->next_desc = 0;
+
+		dev_dbg(hsotg->dev, "%s: Restarted isochronous endpoint\n",
+			__func__);
+	}
+}
+
 /**
  * dwc2_hsotg_rx_data - receive data from the FIFO for an endpoint
  * @hsotg: The device state.
@@ -2445,12 +2703,28 @@ static void dwc2_gadget_handle_out_token_ep_disabled(struct dwc2_hsotg_ep *ep)
 	struct dwc2_hsotg *hsotg = ep->parent;
 	int dir_in = ep->dir_in;
 	u32 doepmsk;
+	u32 tmp;
 
 	if (dir_in || !ep->isochronous)
 		return;
 
+	/*
+	 * Store frame in which irq was asserted here, as
+	 * it can change while completing request below.
+	 */
+	tmp = dwc2_hsotg_read_frameno(hsotg);
+
 	dwc2_hsotg_complete_request(hsotg, ep, get_ep_head(ep), -ENODATA);
 
+	if (using_desc_dma(hsotg)) {
+		if (ep->target_frame == TARGET_FRAME_INITIAL) {
+			/* Start first ISO Out */
+			ep->target_frame = tmp;
+			dwc2_gadget_start_isoc_ddma(ep);
+		}
+		return;
+	}
+
 	if (ep->interval > 1 &&
 	    ep->target_frame == TARGET_FRAME_INITIAL) {
 		u32 dsts;
@@ -2499,6 +2773,12 @@ static void dwc2_gadget_handle_nak(struct dwc2_hsotg_ep *hs_ep)
 
 	if (hs_ep->target_frame == TARGET_FRAME_INITIAL) {
 		hs_ep->target_frame = dwc2_hsotg_read_frameno(hsotg);
+
+		if (using_desc_dma(hsotg)) {
+			dwc2_gadget_start_isoc_ddma(hs_ep);
+			return;
+		}
+
 		if (hs_ep->interval > 1) {
 			u32 ctrl = dwc2_readl(hsotg->regs +
 					      DIEPCTL(hs_ep->index));
@@ -2560,11 +2840,17 @@ static void dwc2_hsotg_epint(struct dwc2_hsotg *hsotg, unsigned int idx,
 			__func__, dwc2_readl(hsotg->regs + epctl_reg),
 			dwc2_readl(hsotg->regs + epsiz_reg));
 
-		/*
-		 * we get OutDone from the FIFO, so we only need to look
-		 * at completing IN requests here
-		 */
-		if (dir_in) {
+		/* In DDMA handle isochronous requests separately */
+		if (using_desc_dma(hsotg) && hs_ep->isochronous) {
+			dwc2_gadget_complete_isoc_request_ddma(hs_ep);
+			/* Try to start next isoc request */
+			dwc2_gadget_start_next_isoc_ddma(hs_ep);
+		} else if (dir_in) {
+			/*
+			 * We get OutDone from the FIFO, so we only
+			 * need to look at completing IN requests here
+			 * if operating slave mode
+			 */
 			if (hs_ep->isochronous && hs_ep->interval > 1)
 				dwc2_gadget_incr_frame_num(hs_ep);
 
@@ -2627,6 +2913,19 @@ static void dwc2_hsotg_epint(struct dwc2_hsotg *hsotg, unsigned int idx,
 	if (ints & DXEPINT_BACK2BACKSETUP)
 		dev_dbg(hsotg->dev, "%s: B2BSetup/INEPNakEff\n", __func__);
 
+	if (ints & DXEPINT_BNAINTR) {
+		dev_dbg(hsotg->dev, "%s: BNA interrupt\n", __func__);
+
+		/*
+		 * Try to start next isoc request, if any.
+		 * Sometimes the endpoint remains enabled after BNA interrupt
+		 * assertion, which is not expected, hence we can enter here
+		 * couple of times.
+		 */
+		if (hs_ep->isochronous)
+			dwc2_gadget_start_next_isoc_ddma(hs_ep);
+	}
+
 	if (dir_in && !hs_ep->isochronous) {
 		/* not sure if this is important, but we'll clear it anyway */
 		if (ints & DXEPINT_INTKNTXFEMP) {