Staging: USB/IP: add common functions needed

This adds the common functions needed by both the host and client side
of the USB/IP code.

Brian Merrell cleaned up a lot of this code and submitted it for
inclusion.  Greg also did a lot of cleanup.
Signed-off-by: Brian G. Merrell <bgmerrell@novell.com>
Cc: Takahiro Hirofuchi <hirofuchi@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/Kconfig

@@ -33,4 +33,6 @@ source "drivers/staging/me4000/Kconfig"
 
 source "drivers/staging/go7007/Kconfig"
 
+source "drivers/staging/usbip/Kconfig"
+
 endif # STAGING

drivers/staging/Makefile

@@ -5,3 +5,4 @@ obj-$(CONFIG_SLICOSS)		+= slicoss/
 obj-$(CONFIG_SXG)		+= sxg/
 obj-$(CONFIG_ME4000)		+= me4000/
 obj-$(CONFIG_VIDEO_GO7007)	+= go7007/
+obj-$(CONFIG_USB_IP_COMMON)	+= usbip/

drivers/staging/usbip/Kconfig

+config USB_IP_COMMON
+	tristate "USB IP support (EXPERIMENTAL)"
+	depends on USB && EXPERIMENTAL
+	default N
+	---help---
+	  This enables pushing USB packets over IP to allow remote
+	  machines access to USB devices directly.  For more details,
+	  and links to the userspace utility programs to let this work
+	  properly, see http://usbip.naist.jp/
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbip_common_mod.
+
+	  If unsure, say N.

drivers/staging/usbip/Makefile

+obj-$(CONFIG_USB_IP_COMMON) += usbip_common_mod.o
+usbip_common_mod-objs := usbip_common.o usbip_event.o
+
+ifeq ($(CONFIG_USB_DEBUG),y)
+	EXTRA_CFLAGS += -DDEBUG
+endif

drivers/staging/usbip/README

+TODO:
+	- more discussion about the protocol
+	- testing
+	- review of the userspace interface
+
+Please send patches for this code to Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/usbip/usbip_event.c

+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ *
+ * This 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 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+ * USA.
+ */
+
+#include "usbip_common.h"
+
+static int event_handler(struct usbip_device *ud)
+{
+	dbg_eh("enter\n");
+
+	/*
+	 * Events are handled by only this thread.
+	 */
+	while (usbip_event_happend(ud)) {
+		dbg_eh("pending event %lx\n", ud->event);
+
+		/*
+		 * NOTE: shutdown must come first.
+		 * Shutdown the device.
+		 */
+		if (ud->event & USBIP_EH_SHUTDOWN) {
+			ud->eh_ops.shutdown(ud);
+
+			ud->event &= ~USBIP_EH_SHUTDOWN;
+
+			break;
+		}
+
+		/* Stop the error handler. */
+		if (ud->event & USBIP_EH_BYE)
+			return -1;
+
+		/* Reset the device. */
+		if (ud->event & USBIP_EH_RESET) {
+			ud->eh_ops.reset(ud);
+
+			ud->event &= ~USBIP_EH_RESET;
+
+			break;
+		}
+
+		/* Mark the device as unusable. */
+		if (ud->event & USBIP_EH_UNUSABLE) {
+			ud->eh_ops.unusable(ud);
+
+			ud->event &= ~USBIP_EH_UNUSABLE;
+
+			break;
+		}
+
+		/* NOTREACHED */
+		printk(KERN_ERR "%s: unknown event\n", __func__);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void event_handler_loop(struct usbip_task *ut)
+{
+	struct usbip_device *ud = container_of(ut, struct usbip_device, eh);
+
+	while (1) {
+		if (signal_pending(current)) {
+			dbg_eh("signal catched!\n");
+			break;
+		}
+
+		if (event_handler(ud) < 0)
+			break;
+
+		wait_event_interruptible(ud->eh_waitq, usbip_event_happend(ud));
+		dbg_eh("wakeup\n");
+	}
+}
+
+void usbip_start_eh(struct usbip_device *ud)
+{
+	struct usbip_task *eh = &ud->eh;
+
+	init_waitqueue_head(&ud->eh_waitq);
+	ud->event = 0;
+
+	usbip_task_init(eh, "usbip_eh", event_handler_loop);
+
+	kernel_thread(usbip_thread, (void *)eh, 0);
+
+	wait_for_completion(&eh->thread_done);
+}
+EXPORT_SYMBOL_GPL(usbip_start_eh);
+
+void usbip_stop_eh(struct usbip_device *ud)
+{
+	struct usbip_task *eh = &ud->eh;
+
+	wait_for_completion(&eh->thread_done);
+	dbg_eh("usbip_eh has finished\n");
+}
+EXPORT_SYMBOL_GPL(usbip_stop_eh);
+
+void usbip_event_add(struct usbip_device *ud, unsigned long event)
+{
+	spin_lock(&ud->lock);
+
+	ud->event |= event;
+
+	wake_up(&ud->eh_waitq);
+
+	spin_unlock(&ud->lock);
+}
+EXPORT_SYMBOL_GPL(usbip_event_add);
+
+int usbip_event_happend(struct usbip_device *ud)
+{
+	int happend = 0;
+
+	spin_lock(&ud->lock);
+
+	if (ud->event != 0)
+		happend = 1;
+
+	spin_unlock(&ud->lock);
+
+	return happend;
+}
+EXPORT_SYMBOL_GPL(usbip_event_happend);