usb gadget zero: split out loopback config

This splits the gadget zero "loopback" configuration into a standalone
"configuration driver", building on the composite gadget framework code.
It doesn't yet pull the original code out of gadget zero or update how
that driver is built.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/f_loopback.c

+/*
+ * f_loopback.c - USB peripheral loopback configuration driver
+ *
+ * Copyright (C) 2003-2008 David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+
+#include "g_zero.h"
+#include "gadget_chips.h"
+
+
+/*
+ * LOOPBACK FUNCTION ... a testing vehicle for USB peripherals,
+ *
+ * This takes messages of various sizes written OUT to a device, and loops
+ * them back so they can be read IN from it.  It has been used by certain
+ * test applications.  It supports limited testing of data queueing logic.
+ *
+ *
+ * This is currently packaged as a configuration driver, which can't be
+ * combined with other functions to make composite devices.  However, it
+ * can be combined with other independent configurations.
+ */
+struct f_loopback {
+	struct usb_function	function;
+
+	struct usb_ep		*in_ep;
+	struct usb_ep		*out_ep;
+};
+
+static inline struct f_loopback *func_to_loop(struct usb_function *f)
+{
+	return container_of(f, struct f_loopback, function);
+}
+
+static unsigned qlen = 32;
+module_param(qlen, uint, 0);
+MODULE_PARM_DESC(qlenn, "depth of loopback queue");
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_interface_descriptor loopback_intf = {
+	.bLength =		sizeof loopback_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_VENDOR_SPEC,
+	/* .iInterface = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor fs_source_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_sink_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *fs_loopback_descs[] = {
+	(struct usb_descriptor_header *) &loopback_intf,
+	(struct usb_descriptor_header *) &fs_sink_desc,
+	(struct usb_descriptor_header *) &fs_source_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_source_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_sink_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *hs_loopback_descs[] = {
+	(struct usb_descriptor_header *) &loopback_intf,
+	(struct usb_descriptor_header *) &hs_source_desc,
+	(struct usb_descriptor_header *) &hs_sink_desc,
+	NULL,
+};
+
+/* function-specific strings: */
+
+static struct usb_string strings_loopback[] = {
+	[0].s = "loop input to output",
+	{  }			/* end of list */
+};
+
+static struct usb_gadget_strings stringtab_loop = {
+	.language	= 0x0409,	/* en-us */
+	.strings	= strings_loopback,
+};
+
+static struct usb_gadget_strings *loopback_strings[] = {
+	&stringtab_loop,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int __init
+loopback_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_loopback	*loop = func_to_loop(f);
+	int			id;
+
+	/* allocate interface ID(s) */
+	id = usb_interface_id(c, f);
+	if (id < 0)
+		return id;
+	loopback_intf.bInterfaceNumber = id;
+
+	/* allocate endpoints */
+
+	loop->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_source_desc);
+	if (!loop->in_ep) {
+autoconf_fail:
+		ERROR(cdev, "%s: can't autoconfigure on %s\n",
+			f->name, cdev->gadget->name);
+		return -ENODEV;
+	}
+	loop->in_ep->driver_data = cdev;	/* claim */
+
+	loop->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_sink_desc);
+	if (!loop->out_ep)
+		goto autoconf_fail;
+	loop->out_ep->driver_data = cdev;	/* claim */
+
+	/* support high speed hardware */
+	if (gadget_is_dualspeed(c->cdev->gadget)) {
+		hs_source_desc.bEndpointAddress =
+				fs_source_desc.bEndpointAddress;
+		hs_sink_desc.bEndpointAddress =
+				fs_sink_desc.bEndpointAddress;
+		f->hs_descriptors = hs_loopback_descs;
+	}
+
+	DBG(cdev, "%s speed %s: IN/%s, OUT/%s\n",
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			f->name, loop->in_ep->name, loop->out_ep->name);
+	return 0;
+}
+
+static void
+loopback_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	kfree(func_to_loop(f));
+}
+
+static void loopback_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_loopback	*loop = ep->driver_data;
+	struct usb_composite_dev *cdev = loop->function.config->cdev;
+	int			status = req->status;
+
+	switch (status) {
+
+	case 0:				/* normal completion? */
+		if (ep == loop->out_ep) {
+			/* loop this OUT packet back IN to the host */
+			req->zero = (req->actual < req->length);
+			req->length = req->actual;
+			status = usb_ep_queue(loop->in_ep, req, GFP_ATOMIC);
+			if (status == 0)
+				return;
+
+			/* "should never get here" */
+			ERROR(cdev, "can't loop %s to %s: %d\n",
+				ep->name, loop->in_ep->name,
+				status);
+		}
+
+		/* queue the buffer for some later OUT packet */
+		req->length = buflen;
+		status = usb_ep_queue(loop->out_ep, req, GFP_ATOMIC);
+		if (status == 0)
+			return;
+
+		/* "should never get here" */
+		/* FALLTHROUGH */
+
+	default:
+		ERROR(cdev, "%s loop complete --> %d, %d/%d\n", ep->name,
+				status, req->actual, req->length);
+		/* FALLTHROUGH */
+
+	/* NOTE:  since this driver doesn't maintain an explicit record
+	 * of requests it submitted (just maintains qlen count), we
+	 * rely on the hardware driver to clean up on disconnect or
+	 * endpoint disable.
+	 */
+	case -ECONNABORTED:		/* hardware forced ep reset */
+	case -ECONNRESET:		/* request dequeued */
+	case -ESHUTDOWN:		/* disconnect from host */
+		free_ep_req(ep, req);
+		return;
+	}
+}
+
+static void disable_loopback(struct f_loopback *loop)
+{
+	struct usb_composite_dev	*cdev;
+
+	cdev = loop->function.config->cdev;
+	disable_endpoints(cdev, loop->in_ep, loop->out_ep);
+	VDBG(cdev, "%s disabled\n", loop->function.name);
+}
+
+static int
+enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
+{
+	int					result = 0;
+	const struct usb_endpoint_descriptor	*src, *sink;
+	struct usb_ep				*ep;
+	struct usb_request			*req;
+	unsigned				i;
+
+	src = ep_choose(cdev->gadget, &hs_source_desc, &fs_source_desc);
+	sink = ep_choose(cdev->gadget, &hs_sink_desc, &fs_sink_desc);
+
+	/* one endpoint writes data back IN to the host */
+	ep = loop->in_ep;
+	result = usb_ep_enable(ep, src);
+	if (result < 0)
+		return result;
+	ep->driver_data = loop;
+
+	/* one endpoint just reads OUT packets */
+	ep = loop->out_ep;
+	result = usb_ep_enable(ep, sink);
+	if (result < 0) {
+fail0:
+		ep = loop->in_ep;
+		usb_ep_disable(ep);
+		ep->driver_data = NULL;
+		return result;
+	}
+	ep->driver_data = loop;
+
+	/* allocate a bunch of read buffers and queue them all at once.
+	 * we buffer at most 'qlen' transfers; fewer if any need more
+	 * than 'buflen' bytes each.
+	 */
+	for (i = 0; i < qlen && result == 0; i++) {
+		req = alloc_ep_req(ep);
+		if (req) {
+			req->complete = loopback_complete;
+			result = usb_ep_queue(ep, req, GFP_ATOMIC);
+			if (result)
+				ERROR(cdev, "%s queue req --> %d\n",
+						ep->name, result);
+		} else {
+			usb_ep_disable(ep);
+			ep->driver_data = NULL;
+			result = -ENOMEM;
+			goto fail0;
+		}
+	}
+
+	DBG(cdev, "%s enabled\n", loop->function.name);
+	return result;
+}
+
+static int loopback_set_alt(struct usb_function *f,
+		unsigned intf, unsigned alt)
+{
+	struct f_loopback	*loop = func_to_loop(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	/* we know alt is zero */
+	if (loop->in_ep->driver_data)
+		disable_loopback(loop);
+	return enable_loopback(cdev, loop);
+}
+
+static void loopback_disable(struct usb_function *f)
+{
+	struct f_loopback	*loop = func_to_loop(f);
+
+	disable_loopback(loop);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int __init loopback_bind_config(struct usb_configuration *c)
+{
+	struct f_loopback	*loop;
+	int			status;
+
+	loop = kzalloc(sizeof *loop, GFP_KERNEL);
+	if (!loop)
+		return -ENOMEM;
+
+	loop->function.name = "loopback";
+	loop->function.descriptors = fs_loopback_descs;
+	loop->function.bind = loopback_bind;
+	loop->function.unbind = loopback_unbind;
+	loop->function.set_alt = loopback_set_alt;
+	loop->function.disable = loopback_disable;
+
+	status = usb_add_function(c, &loop->function);
+	if (status)
+		kfree(loop);
+	return status;
+}
+
+static struct usb_configuration loopback_driver = {
+	.label		= "loopback",
+	.strings	= loopback_strings,
+	.bind		= loopback_bind_config,
+	.bConfigurationValue = 2,
+	.bmAttributes	= USB_CONFIG_ATT_SELFPOWER,
+	.bMaxPower	= 1,	/* 2 mA, minimal */
+	/* .iConfiguration = DYNAMIC */
+};
+
+/**
+ * loopback_add - add a loopback testing configuration to a device
+ * @cdev: the device to support the loopback configuration
+ */
+int __init loopback_add(struct usb_composite_dev *cdev)
+{
+	int id;
+
+	/* allocate string ID(s) */
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+	strings_loopback[0].id = id;
+
+	loopback_intf.iInterface = id;
+	loopback_driver.iConfiguration = id;
+
+	/* support OTG systems */
+	if (gadget_is_otg(cdev->gadget)) {
+		loopback_driver.descriptors = otg_desc;
+		loopback_driver.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+	}
+
+	return usb_add_config(cdev, &loopback_driver);
+}

drivers/usb/gadget/g_zero.h

@@ -9,6 +9,7 @@
 #include <linux/usb/composite.h>
 
 /* global state */
+extern unsigned buflen;
 extern const struct usb_descriptor_header *otg_desc[];
 
 /* common utilities */
@@ -19,5 +20,6 @@ void disable_endpoints(struct usb_composite_dev *cdev,
 
 /* configuration-specific linkup */
 int sourcesink_add(struct usb_composite_dev *cdev);
+int loopback_add(struct usb_composite_dev *cdev);
 
 #endif /* __G_ZERO_H */