usb: ci_udc: allow multiple buffer allocs per ep

Modify ci_ep_alloc_request() to return a dynamically allocated request
object, rather than a singleton that's part of the endpoint. This
requires moving various state from the endpoint structure to the request
structure, since we need one copy per request.

The "fast bounce buffer" b_fast is removed by this change rather than
moved to the request object. Instead, we enhance the bounce buffer logic
in ci_bounce()/ci_debounce() to keep the bounce buffer around between
request submissions. This avoids the need to allocate an arbitrarily-
sized bounce buffer up-front, yet avoids incurring the allocation
overhead each time a request is submitted.

A future enhancement would be to actually submit multiple requests to HW
at once. The Linux driver shows that this is possible. That might improve
throughput (depending on the USB protocol in use), since USB could be
performing a transfer to one HW buffer in parallel with whatever SW
actions U-Boot performs on another buffer. However, I have not made this
change as part of this patch, in order to keep SW changes related to
buffer management separate from any change in the way the HW is
programmed.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

drivers/usb/gadget/ci_udc.c

@@ -205,13 +205,26 @@ static void ci_invalidate_qtd(int ep_num)
 static struct usb_request *
 ci_ep_alloc_request(struct usb_ep *ep, unsigned int gfp_flags)
 {
-	struct ci_ep *ci_ep = container_of(ep, struct ci_ep, ep);
-	return &ci_ep->req;
+	struct ci_req *ci_req;
+
+	ci_req = memalign(ARCH_DMA_MINALIGN, sizeof(*ci_req));
+	if (!ci_req)
+		return NULL;
+
+	INIT_LIST_HEAD(&ci_req->queue);
+	ci_req->b_buf = 0;
+
+	return &ci_req->req;
 }
 
-static void ci_ep_free_request(struct usb_ep *ep, struct usb_request *_req)
+static void ci_ep_free_request(struct usb_ep *ep, struct usb_request *req)
 {
-	return;
+	struct ci_req *ci_req;
+
+	ci_req = container_of(req, struct ci_req, req);
+	if (ci_req->b_buf)
+		free(ci_req->b_buf);
+	free(ci_req);
 }
 
 static void ep_enable(int num, int in, int maxpacket)
@@ -267,99 +280,102 @@ static int ci_ep_disable(struct usb_ep *ep)
 	return 0;
 }
 
-static int ci_bounce(struct ci_ep *ep, int in)
+static int ci_bounce(struct ci_req *ci_req, int in)
 {
-	uint32_t addr = (uint32_t)ep->req.buf;
-	uint32_t ba;
+	struct usb_request *req = &ci_req->req;
+	uint32_t addr = (uint32_t)req->buf;
+	uint32_t hwaddr;
+	uint32_t aligned_used_len;
 
 	/* Input buffer address is not aligned. */
 	if (addr & (ARCH_DMA_MINALIGN - 1))
 		goto align;
 
 	/* Input buffer length is not aligned. */
-	if (ep->req.length & (ARCH_DMA_MINALIGN - 1))
+	if (req->length & (ARCH_DMA_MINALIGN - 1))
 		goto align;
 
 	/* The buffer is well aligned, only flush cache. */
-	ep->b_len = ep->req.length;
-	ep->b_buf = ep->req.buf;
+	ci_req->hw_len = req->length;
+	ci_req->hw_buf = req->buf;
 	goto flush;
 
 align:
-	/* Use internal buffer for small payloads. */
-	if (ep->req.length <= 64) {
-		ep->b_len = 64;
-		ep->b_buf = ep->b_fast;
-	} else {
-		ep->b_len = roundup(ep->req.length, ARCH_DMA_MINALIGN);
-		ep->b_buf = memalign(ARCH_DMA_MINALIGN, ep->b_len);
-		if (!ep->b_buf)
+	if (ci_req->b_buf && req->length > ci_req->b_len) {
+		free(ci_req->b_buf);
+		ci_req->b_buf = 0;
+	}
+	if (!ci_req->b_buf) {
+		ci_req->b_len = roundup(req->length, ARCH_DMA_MINALIGN);
+		ci_req->b_buf = memalign(ARCH_DMA_MINALIGN, ci_req->b_len);
+		if (!ci_req->b_buf)
 			return -ENOMEM;
 	}
+	ci_req->hw_len = ci_req->b_len;
+	ci_req->hw_buf = ci_req->b_buf;
+
 	if (in)
-		memcpy(ep->b_buf, ep->req.buf, ep->req.length);
+		memcpy(ci_req->hw_buf, req->buf, req->length);
 
 flush:
-	ba = (uint32_t)ep->b_buf;
-	flush_dcache_range(ba, ba + ep->b_len);
+	hwaddr = (uint32_t)ci_req->hw_buf;
+	aligned_used_len = roundup(req->length, ARCH_DMA_MINALIGN);
+	flush_dcache_range(hwaddr, hwaddr + aligned_used_len);
 
 	return 0;
 }
 
-static void ci_debounce(struct ci_ep *ep, int in)
+static void ci_debounce(struct ci_req *ci_req, int in)
 {
-	uint32_t addr = (uint32_t)ep->req.buf;
-	uint32_t ba = (uint32_t)ep->b_buf;
+	struct usb_request *req = &ci_req->req;
+	uint32_t addr = (uint32_t)req->buf;
+	uint32_t hwaddr = (uint32_t)ci_req->hw_buf;
+	uint32_t aligned_used_len;
 
-	if (in) {
-		if (addr == ba)
-			return;		/* not a bounce */
-		goto free;
-	}
-	invalidate_dcache_range(ba, ba + ep->b_len);
+	if (in)
+		return;
+
+	aligned_used_len = roundup(req->actual, ARCH_DMA_MINALIGN);
+	invalidate_dcache_range(hwaddr, hwaddr + aligned_used_len);
 
-	if (addr == ba)
-		return;		/* not a bounce */
+	if (addr == hwaddr)
+		return; /* not a bounce */
 
-	memcpy(ep->req.buf, ep->b_buf, ep->req.actual);
-free:
-	/* Large payloads use allocated buffer, free it. */
-	if (ep->b_buf != ep->b_fast)
-		free(ep->b_buf);
+	memcpy(req->buf, ci_req->hw_buf, req->actual);
 }
 
-static int ci_ep_queue(struct usb_ep *ep,
-		struct usb_request *req, gfp_t gfp_flags)
+static void ci_ep_submit_next_request(struct ci_ep *ci_ep)
 {
-	struct ci_ep *ci_ep = container_of(ep, struct ci_ep, ep);
 	struct ci_udc *udc = (struct ci_udc *)controller.ctrl->hcor;
 	struct ept_queue_item *item;
 	struct ept_queue_head *head;
-	int bit, num, len, in, ret;
+	int bit, num, len, in;
+	struct ci_req *ci_req;
+
+	ci_ep->req_primed = true;
+
 	num = ci_ep->desc->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
 	in = (ci_ep->desc->bEndpointAddress & USB_DIR_IN) != 0;
 	item = ci_get_qtd(num, in);
 	head = ci_get_qh(num, in);
-	len = req->length;
 
-	ret = ci_bounce(ci_ep, in);
-	if (ret)
-		return ret;
+	ci_req = list_first_entry(&ci_ep->queue, struct ci_req, queue);
+	len = ci_req->req.length;
 
 	item->next = TERMINATE;
 	item->info = INFO_BYTES(len) | INFO_IOC | INFO_ACTIVE;
-	item->page0 = (uint32_t)ci_ep->b_buf;
-	item->page1 = ((uint32_t)ci_ep->b_buf & 0xfffff000) + 0x1000;
-	item->page2 = ((uint32_t)ci_ep->b_buf & 0xfffff000) + 0x2000;
-	item->page3 = ((uint32_t)ci_ep->b_buf & 0xfffff000) + 0x3000;
-	item->page4 = ((uint32_t)ci_ep->b_buf & 0xfffff000) + 0x4000;
+	item->page0 = (uint32_t)ci_req->hw_buf;
+	item->page1 = ((uint32_t)ci_req->hw_buf & 0xfffff000) + 0x1000;
+	item->page2 = ((uint32_t)ci_req->hw_buf & 0xfffff000) + 0x2000;
+	item->page3 = ((uint32_t)ci_req->hw_buf & 0xfffff000) + 0x3000;
+	item->page4 = ((uint32_t)ci_req->hw_buf & 0xfffff000) + 0x4000;
 	ci_flush_qtd(num);
 
 	head->next = (unsigned) item;
 	head->info = 0;
 
-	DBG("ept%d %s queue len %x, buffer %p\n",
-	    num, in ? "in" : "out", len, ci_ep->b_buf);
+	DBG("ept%d %s queue len %x, req %p, buffer %p\n",
+	    num, in ? "in" : "out", len, ci_req, ci_req->hw_buf);
 	ci_flush_qh(num);
 
 	if (in)
@@ -368,6 +384,29 @@ static int ci_ep_queue(struct usb_ep *ep,
 		bit = EPT_RX(num);
 
 	writel(bit, &udc->epprime);
+}
+
+static int ci_ep_queue(struct usb_ep *ep,
+		struct usb_request *req, gfp_t gfp_flags)
+{
+	struct ci_ep *ci_ep = container_of(ep, struct ci_ep, ep);
+	struct ci_req *ci_req = container_of(req, struct ci_req, req);
+	int in, ret;
+	int __maybe_unused num;
+
+	num = ci_ep->desc->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
+	in = (ci_ep->desc->bEndpointAddress & USB_DIR_IN) != 0;
+
+	ret = ci_bounce(ci_req, in);
+	if (ret)
+		return ret;
+
+	DBG("ept%d %s pre-queue req %p, buffer %p\n",
+	    num, in ? "in" : "out", ci_req, ci_req->hw_buf);
+	list_add_tail(&ci_req->queue, &ci_ep->queue);
+
+	if (!ci_ep->req_primed)
+		ci_ep_submit_next_request(ci_ep);
 
 	return 0;
 }
@@ -376,6 +415,8 @@ static void handle_ep_complete(struct ci_ep *ep)
 {
 	struct ept_queue_item *item;
 	int num, in, len;
+	struct ci_req *ci_req;
+
 	num = ep->desc->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
 	in = (ep->desc->bEndpointAddress & USB_DIR_IN) != 0;
 	if (num == 0)
@@ -387,16 +428,23 @@ static void handle_ep_complete(struct ci_ep *ep)
 		printf("EP%d/%s FAIL info=%x pg0=%x\n",
 		       num, in ? "in" : "out", item->info, item->page0);
 
+	ci_req = list_first_entry(&ep->queue, struct ci_req, queue);
+	list_del_init(&ci_req->queue);
+	ep->req_primed = false;
+
+	if (!list_empty(&ep->queue))
+		ci_ep_submit_next_request(ep);
+
 	len = (item->info >> 16) & 0x7fff;
-	ep->req.actual = ep->req.length - len;
-	ci_debounce(ep, in);
+	ci_req->req.actual = ci_req->req.length - len;
+	ci_debounce(ci_req, in);
 
-	DBG("ept%d %s complete %x\n",
-			num, in ? "in" : "out", len);
-	ep->req.complete(&ep->ep, &ep->req);
+	DBG("ept%d %s req %p, complete %x\n",
+	    num, in ? "in" : "out", ci_req, len);
+	ci_req->req.complete(&ep->ep, &ci_req->req);
 	if (num == 0) {
-		ep->req.length = 0;
-		usb_ep_queue(&ep->ep, &ep->req, 0);
+		ci_req->req.length = 0;
+		usb_ep_queue(&ep->ep, &ci_req->req, 0);
 		ep->desc = &ep0_in_desc;
 	}
 }
@@ -405,13 +453,18 @@ static void handle_ep_complete(struct ci_ep *ep)
 
 static void handle_setup(void)
 {
-	struct usb_request *req = &controller.ep[0].req;
+	struct ci_ep *ci_ep = &controller.ep[0];
+	struct ci_req *ci_req;
+	struct usb_request *req;
 	struct ci_udc *udc = (struct ci_udc *)controller.ctrl->hcor;
 	struct ept_queue_head *head;
 	struct usb_ctrlrequest r;
 	int status = 0;
 	int num, in, _num, _in, i;
 	char *buf;
+
+	ci_req = list_first_entry(&ci_ep->queue, struct ci_req, queue);
+	req = &ci_req->req;
 	head = ci_get_qh(0, 0);	/* EP0 OUT */
 
 	ci_invalidate_qh(0);
@@ -424,6 +477,9 @@ static void handle_setup(void)
 	DBG("handle setup %s, %x, %x index %x value %x\n", reqname(r.bRequest),
 	    r.bRequestType, r.bRequest, r.wIndex, r.wValue);
 
+	list_del_init(&ci_req->queue);
+	ci_ep->req_primed = false;
+
 	switch (SETUP(r.bRequestType, r.bRequest)) {
 	case SETUP(USB_RECIP_ENDPOINT, USB_REQ_CLEAR_FEATURE):
 		_num = r.wIndex & 15;
@@ -701,6 +757,8 @@ static int ci_udc_probe(void)
 	/* Init EP 0 */
 	memcpy(&controller.ep[0].ep, &ci_ep_init[0], sizeof(*ci_ep_init));
 	controller.ep[0].desc = &ep0_in_desc;
+	INIT_LIST_HEAD(&controller.ep[0].queue);
+	controller.ep[0].req_primed = false;
 	controller.gadget.ep0 = &controller.ep[0].ep;
 	INIT_LIST_HEAD(&controller.gadget.ep0->ep_list);
 
@@ -708,6 +766,8 @@ static int ci_udc_probe(void)
 	for (i = 1; i < NUM_ENDPOINTS; i++) {
 		memcpy(&controller.ep[i].ep, &ci_ep_init[1],
 		       sizeof(*ci_ep_init));
+		INIT_LIST_HEAD(&controller.ep[i].queue);
+		controller.ep[i].req_primed = false;
 		list_add_tail(&controller.ep[i].ep.ep_list,
 			      &controller.gadget.ep_list);
 	}

drivers/usb/gadget/ci_udc.h

@@ -77,15 +77,22 @@ struct ci_udc {
 #define CTRL_TXT_BULK	(2 << 18)
 #define CTRL_RXT_BULK	(2 << 2)
 
+struct ci_req {
+	struct usb_request	req;
+	struct list_head	queue;
+	/* Bounce buffer allocated if needed to align the transfer */
+	uint8_t *b_buf;
+	uint32_t b_len;
+	/* Buffer for the current transfer. Either req.buf/len or b_buf/len */
+	uint8_t *hw_buf;
+	uint32_t hw_len;
+};
+
 struct ci_ep {
 	struct usb_ep ep;
 	struct list_head queue;
+	bool req_primed;
 	const struct usb_endpoint_descriptor *desc;
-
-	struct usb_request req;
-	uint8_t *b_buf;
-	uint32_t b_len;
-	uint8_t b_fast[64] __aligned(ARCH_DMA_MINALIGN);
 };
 
 struct ci_drv {