usbip: vudc: Add vudc_transfer

This file contains a function that simulates USB traffic, based on
the one in dummy_hcd. Is also handles udc-directed control
requests, and contains functions for setting up and controlling
a timer for the emulation.

This commit is a result of cooperation between Samsung R&D Institute
Poland and Open Operating Systems Student Society at University
of Warsaw (O2S3@UW) consisting of:

    Igor Kotrasinski <ikotrasinsk@gmail.com>
    Karol Kosik <karo9@interia.eu>
    Ewelina Kosmider <3w3lfin@gmail.com>
    Dawid Lazarczyk <lazarczyk.dawid@gmail.com>
    Piotr Szulc <ps347277@students.mimuw.edu.pl>

Tutor and project owner:
    Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: NIgor Kotrasinski <i.kotrasinsk@samsung.com>
Signed-off-by: NKarol Kosik <karo9@interia.eu>
Signed-off-by: NKrzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/vudc_transfer.c

+/*
+ * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
+ * Copyright (C) 2015-2016 Samsung Electronics
+ *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
+ *
+ * Based on dummy_hcd.c, which is:
+ * Copyright (C) 2003 David Brownell
+ * Copyright (C) 2003-2005 Alan Stern
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/usb.h>
+#include <linux/timer.h>
+#include <linux/usb/ch9.h>
+
+#include "vudc.h"
+
+#define DEV_REQUEST	(USB_TYPE_STANDARD | USB_RECIP_DEVICE)
+#define DEV_INREQUEST	(DEV_REQUEST | USB_DIR_IN)
+#define INTF_REQUEST	(USB_TYPE_STANDARD | USB_RECIP_INTERFACE)
+#define INTF_INREQUEST	(INTF_REQUEST | USB_DIR_IN)
+#define EP_REQUEST	(USB_TYPE_STANDARD | USB_RECIP_ENDPOINT)
+#define EP_INREQUEST	(EP_REQUEST | USB_DIR_IN)
+
+static int get_frame_limit(enum usb_device_speed speed)
+{
+	switch (speed) {
+	case USB_SPEED_LOW:
+		return 8 /*bytes*/ * 12 /*packets*/;
+	case USB_SPEED_FULL:
+		return 64 /*bytes*/ * 19 /*packets*/;
+	case USB_SPEED_HIGH:
+		return 512 /*bytes*/ * 13 /*packets*/ * 8 /*uframes*/;
+	case USB_SPEED_SUPER:
+		/* Bus speed is 500000 bytes/ms, so use a little less */
+		return 490000;
+	default:
+		/* error */
+		return -1;
+	}
+
+}
+
+/*
+ * handle_control_request() - handles all control transfers
+ * @udc: pointer to vudc
+ * @urb: the urb request to handle
+ * @setup: pointer to the setup data for a USB device control
+ *	 request
+ * @status: pointer to request handling status
+ *
+ * Return 0 - if the request was handled
+ *	  1 - if the request wasn't handles
+ *	  error code on error
+ *
+ * Adapted from drivers/usb/gadget/udc/dummy_hcd.c
+ */
+static int handle_control_request(struct vudc *udc, struct urb *urb,
+				  struct usb_ctrlrequest *setup,
+				  int *status)
+{
+	struct vep	*ep2;
+	int		ret_val = 1;
+	unsigned	w_index;
+	unsigned	w_value;
+
+	w_index = le16_to_cpu(setup->wIndex);
+	w_value = le16_to_cpu(setup->wValue);
+	switch (setup->bRequest) {
+	case USB_REQ_SET_ADDRESS:
+		if (setup->bRequestType != DEV_REQUEST)
+			break;
+		udc->address = w_value;
+		ret_val = 0;
+		*status = 0;
+		break;
+	case USB_REQ_SET_FEATURE:
+		if (setup->bRequestType == DEV_REQUEST) {
+			ret_val = 0;
+			switch (w_value) {
+			case USB_DEVICE_REMOTE_WAKEUP:
+				break;
+			case USB_DEVICE_B_HNP_ENABLE:
+				udc->gadget.b_hnp_enable = 1;
+				break;
+			case USB_DEVICE_A_HNP_SUPPORT:
+				udc->gadget.a_hnp_support = 1;
+				break;
+			case USB_DEVICE_A_ALT_HNP_SUPPORT:
+				udc->gadget.a_alt_hnp_support = 1;
+				break;
+			default:
+				ret_val = -EOPNOTSUPP;
+			}
+			if (ret_val == 0) {
+				udc->devstatus |= (1 << w_value);
+				*status = 0;
+			}
+		} else if (setup->bRequestType == EP_REQUEST) {
+			/* endpoint halt */
+			ep2 = find_endpoint(udc, w_index);
+			if (!ep2 || ep2->ep.name == udc->ep[0].ep.name) {
+				ret_val = -EOPNOTSUPP;
+				break;
+			}
+			ep2->halted = 1;
+			ret_val = 0;
+			*status = 0;
+		}
+		break;
+	case USB_REQ_CLEAR_FEATURE:
+		if (setup->bRequestType == DEV_REQUEST) {
+			ret_val = 0;
+			switch (w_value) {
+			case USB_DEVICE_REMOTE_WAKEUP:
+				w_value = USB_DEVICE_REMOTE_WAKEUP;
+				break;
+
+			case USB_DEVICE_U1_ENABLE:
+			case USB_DEVICE_U2_ENABLE:
+			case USB_DEVICE_LTM_ENABLE:
+				ret_val = -EOPNOTSUPP;
+				break;
+			default:
+				ret_val = -EOPNOTSUPP;
+				break;
+			}
+			if (ret_val == 0) {
+				udc->devstatus &= ~(1 << w_value);
+				*status = 0;
+			}
+		} else if (setup->bRequestType == EP_REQUEST) {
+			/* endpoint halt */
+			ep2 = find_endpoint(udc, w_index);
+			if (!ep2) {
+				ret_val = -EOPNOTSUPP;
+				break;
+			}
+			if (!ep2->wedged)
+				ep2->halted = 0;
+			ret_val = 0;
+			*status = 0;
+		}
+		break;
+	case USB_REQ_GET_STATUS:
+		if (setup->bRequestType == DEV_INREQUEST
+				|| setup->bRequestType == INTF_INREQUEST
+				|| setup->bRequestType == EP_INREQUEST) {
+			char *buf;
+			/*
+			 * device: remote wakeup, selfpowered
+			 * interface: nothing
+			 * endpoint: halt
+			 */
+			buf = (char *)urb->transfer_buffer;
+			if (urb->transfer_buffer_length > 0) {
+				if (setup->bRequestType == EP_INREQUEST) {
+					ep2 = find_endpoint(udc, w_index);
+					if (!ep2) {
+						ret_val = -EOPNOTSUPP;
+						break;
+					}
+					buf[0] = ep2->halted;
+				} else if (setup->bRequestType ==
+					   DEV_INREQUEST) {
+					buf[0] = (u8)udc->devstatus;
+				} else
+					buf[0] = 0;
+			}
+			if (urb->transfer_buffer_length > 1)
+				buf[1] = 0;
+			urb->actual_length = min_t(u32, 2,
+				urb->transfer_buffer_length);
+			ret_val = 0;
+			*status = 0;
+		}
+		break;
+	}
+	return ret_val;
+}
+
+/* Adapted from dummy_hcd.c ; caller must hold lock */
+static int transfer(struct vudc *udc,
+		struct urb *urb, struct vep *ep, int limit)
+{
+	struct vrequest	*req;
+	int sent = 0;
+top:
+	/* if there's no request queued, the device is NAKing; return */
+	list_for_each_entry(req, &ep->req_queue, req_entry) {
+		unsigned	host_len, dev_len, len;
+		void		*ubuf_pos, *rbuf_pos;
+		int		is_short, to_host;
+		int		rescan = 0;
+
+		/*
+		 * 1..N packets of ep->ep.maxpacket each ... the last one
+		 * may be short (including zero length).
+		 *
+		 * writer can send a zlp explicitly (length 0) or implicitly
+		 * (length mod maxpacket zero, and 'zero' flag); they always
+		 * terminate reads.
+		 */
+		host_len = urb->transfer_buffer_length - urb->actual_length;
+		dev_len = req->req.length - req->req.actual;
+		len = min(host_len, dev_len);
+
+		to_host = usb_pipein(urb->pipe);
+		if (unlikely(len == 0))
+			is_short = 1;
+		else {
+			/* send multiple of maxpacket first, then remainder */
+			if (len >= ep->ep.maxpacket) {
+				is_short = 0;
+				if (len % ep->ep.maxpacket > 0)
+					rescan = 1;
+				len -= len % ep->ep.maxpacket;
+			} else {
+				is_short = 1;
+			}
+
+			ubuf_pos = urb->transfer_buffer + urb->actual_length;
+			rbuf_pos = req->req.buf + req->req.actual;
+
+			if (urb->pipe & USB_DIR_IN)
+				memcpy(ubuf_pos, rbuf_pos, len);
+			else
+				memcpy(rbuf_pos, ubuf_pos, len);
+
+			urb->actual_length += len;
+			req->req.actual += len;
+			sent += len;
+		}
+
+		/*
+		 * short packets terminate, maybe with overflow/underflow.
+		 * it's only really an error to write too much.
+		 *
+		 * partially filling a buffer optionally blocks queue advances
+		 * (so completion handlers can clean up the queue) but we don't
+		 * need to emulate such data-in-flight.
+		 */
+		if (is_short) {
+			if (host_len == dev_len) {
+				req->req.status = 0;
+				urb->status = 0;
+			} else if (to_host) {
+				req->req.status = 0;
+				if (dev_len > host_len)
+					urb->status = -EOVERFLOW;
+				else
+					urb->status = 0;
+			} else {
+				urb->status = 0;
+				if (host_len > dev_len)
+					req->req.status = -EOVERFLOW;
+				else
+					req->req.status = 0;
+			}
+
+		/* many requests terminate without a short packet */
+		/* also check if we need to send zlp */
+		} else {
+			if (req->req.length == req->req.actual) {
+				if (req->req.zero && to_host)
+					rescan = 1;
+				else
+					req->req.status = 0;
+			}
+			if (urb->transfer_buffer_length == urb->actual_length) {
+				if (urb->transfer_flags & URB_ZERO_PACKET &&
+				    !to_host)
+					rescan = 1;
+				else
+					urb->status = 0;
+			}
+		}
+
+		/* device side completion --> continuable */
+		if (req->req.status != -EINPROGRESS) {
+
+			list_del_init(&req->req_entry);
+			spin_unlock(&udc->lock);
+			usb_gadget_giveback_request(&ep->ep, &req->req);
+			spin_lock(&udc->lock);
+
+			/* requests might have been unlinked... */
+			rescan = 1;
+		}
+
+		/* host side completion --> terminate */
+		if (urb->status != -EINPROGRESS)
+			break;
+
+		/* rescan to continue with any other queued i/o */
+		if (rescan)
+			goto top;
+	}
+	return sent;
+}
+
+static void v_timer(unsigned long _vudc)
+{
+	struct vudc *udc = (struct vudc *) _vudc;
+	struct transfer_timer *timer = &udc->tr_timer;
+	struct urbp *urb_p, *tmp;
+	unsigned long flags;
+	struct usb_ep *_ep;
+	struct vep *ep;
+	int ret = 0;
+	int total, limit;
+
+	spin_lock_irqsave(&udc->lock, flags);
+
+	total = get_frame_limit(udc->gadget.speed);
+	if (total < 0) {	/* unknown speed, or not set yet */
+		timer->state = VUDC_TR_IDLE;
+		spin_unlock_irqrestore(&udc->lock, flags);
+		return;
+	}
+	/* is it next frame now? */
+	if (time_after(jiffies, timer->frame_start + msecs_to_jiffies(1))) {
+		timer->frame_limit = total;
+		/* FIXME: how to make it accurate? */
+		timer->frame_start = jiffies;
+	} else {
+		total = timer->frame_limit;
+	}
+
+	list_for_each_entry(_ep, &udc->gadget.ep_list, ep_list) {
+		ep = to_vep(_ep);
+		ep->already_seen = 0;
+	}
+
+restart:
+	list_for_each_entry_safe(urb_p, tmp, &udc->urb_queue, urb_entry) {
+		struct urb *urb = urb_p->urb;
+
+		ep = urb_p->ep;
+		if (urb->unlinked)
+			goto return_urb;
+		if (timer->state != VUDC_TR_RUNNING)
+			continue;
+
+		if (!ep) {
+			urb->status = -EPROTO;
+			goto return_urb;
+		}
+
+		/* Used up bandwidth? */
+		if (total <= 0 && ep->type == USB_ENDPOINT_XFER_BULK)
+			continue;
+
+		if (ep->already_seen)
+			continue;
+		ep->already_seen = 1;
+		if (ep == &udc->ep[0] && urb_p->new) {
+			ep->setup_stage = 1;
+			urb_p->new = 0;
+		}
+		if (ep->halted && !ep->setup_stage) {
+			urb->status = -EPIPE;
+			goto return_urb;
+		}
+
+		if (ep == &udc->ep[0] && ep->setup_stage) {
+			/* TODO - flush any stale requests */
+			ep->setup_stage = 0;
+			ep->halted = 0;
+
+			ret = handle_control_request(udc, urb,
+				(struct usb_ctrlrequest *) urb->setup_packet,
+				(&urb->status));
+			if (ret > 0) {
+				spin_unlock(&udc->lock);
+				ret = udc->driver->setup(&udc->gadget,
+					(struct usb_ctrlrequest *)
+					urb->setup_packet);
+				spin_lock(&udc->lock);
+			}
+			if (ret >= 0) {
+				/* no delays (max 64kb data stage) */
+				limit = 64 * 1024;
+				goto treat_control_like_bulk;
+			} else {
+				urb->status = -EPIPE;
+				urb->actual_length = 0;
+				goto return_urb;
+			}
+		}
+
+		limit = total;
+		switch (ep->type) {
+		case USB_ENDPOINT_XFER_ISOC:
+			/* TODO: support */
+			urb->status = -EXDEV;
+			break;
+
+		case USB_ENDPOINT_XFER_INT:
+			/*
+			 * TODO: figure out bandwidth guarantees
+			 * for now, give unlimited bandwidth
+			 */
+			limit += urb->transfer_buffer_length;
+			/* fallthrough */
+		default:
+treat_control_like_bulk:
+			total -= transfer(udc, urb, ep, limit);
+		}
+		if (urb->status == -EINPROGRESS)
+			continue;
+
+return_urb:
+		if (ep)
+			ep->already_seen = ep->setup_stage = 0;
+
+		spin_lock(&udc->lock_tx);
+		list_del(&urb_p->urb_entry);
+		if (!urb->unlinked) {
+			v_enqueue_ret_submit(udc, urb_p);
+		} else {
+			v_enqueue_ret_unlink(udc, urb_p->seqnum,
+					     urb->unlinked);
+			free_urbp_and_urb(urb_p);
+		}
+		wake_up(&udc->tx_waitq);
+		spin_unlock(&udc->lock_tx);
+
+		goto restart;
+	}
+
+	/* TODO - also wait on empty usb_request queues? */
+	if (list_empty(&udc->urb_queue))
+		timer->state = VUDC_TR_IDLE;
+	else
+		mod_timer(&timer->timer,
+			  timer->frame_start + msecs_to_jiffies(1));
+
+	spin_unlock_irqrestore(&udc->lock, flags);
+}
+
+/* All timer functions are run with udc->lock held */
+
+void v_init_timer(struct vudc *udc)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	setup_timer(&t->timer, v_timer, (unsigned long) udc);
+	t->state = VUDC_TR_STOPPED;
+}
+
+void v_start_timer(struct vudc *udc)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	dev_dbg(&udc->pdev->dev, "timer start");
+	switch (t->state) {
+	case VUDC_TR_RUNNING:
+		return;
+	case VUDC_TR_IDLE:
+		return v_kick_timer(udc, jiffies);
+	case VUDC_TR_STOPPED:
+		t->state = VUDC_TR_IDLE;
+		t->frame_start = jiffies;
+		t->frame_limit = get_frame_limit(udc->gadget.speed);
+		return v_kick_timer(udc, jiffies);
+	}
+}
+
+void v_kick_timer(struct vudc *udc, unsigned long time)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	dev_dbg(&udc->pdev->dev, "timer kick");
+	switch (t->state) {
+	case VUDC_TR_RUNNING:
+		return;
+	case VUDC_TR_IDLE:
+		t->state = VUDC_TR_RUNNING;
+		/* fallthrough */
+	case VUDC_TR_STOPPED:
+		/* we may want to kick timer to unqueue urbs */
+		mod_timer(&t->timer, time);
+	}
+}
+
+void v_stop_timer(struct vudc *udc)
+{
+	struct transfer_timer *t = &udc->tr_timer;
+
+	/* timer itself will take care of stopping */
+	dev_dbg(&udc->pdev->dev, "timer stop");
+	t->state = VUDC_TR_STOPPED;
+}