1 files changed, 598 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/f_loopback.c b/drivers/usb/gadget/function/f_loopback.c
new file mode 100644
index 000000000..ae41f556e
--- /dev/null
+++ b/drivers/usb/gadget/function/f_loopback.c
@@ -0,0 +1,598 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * f_loopback.c - USB peripheral loopback configuration driver
+ *
+ * Copyright (C) 2003-2008 David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/usb/composite.h>
+
+#include "g_zero.h"
+#include "u_f.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.
+ */
+struct f_loopback {
+	struct usb_function	function;
+
+	struct usb_ep		*in_ep;
+	struct usb_ep		*out_ep;
+
+	unsigned                qlen;
+	unsigned                buflen;
+};
+
+static inline struct f_loopback *func_to_loop(struct usb_function *f)
+{
+	return container_of(f, struct f_loopback, function);
+}
+
+/*-------------------------------------------------------------------------*/
+
+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_loop_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_loop_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_loop_sink_desc,
+	(struct usb_descriptor_header *) &fs_loop_source_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_loop_source_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_loop_sink_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *hs_loopback_descs[] = {
+	(struct usb_descriptor_header *) &loopback_intf,
+	(struct usb_descriptor_header *) &hs_loop_source_desc,
+	(struct usb_descriptor_header *) &hs_loop_sink_desc,
+	NULL,
+};
+
+/* super speed support: */
+
+static struct usb_endpoint_descriptor ss_loop_source_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_loop_source_comp_desc = {
+	.bLength =		USB_DT_SS_EP_COMP_SIZE,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+	.bMaxBurst =		0,
+	.bmAttributes =		0,
+	.wBytesPerInterval =	0,
+};
+
+static struct usb_endpoint_descriptor ss_loop_sink_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_loop_sink_comp_desc = {
+	.bLength =		USB_DT_SS_EP_COMP_SIZE,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+	.bMaxBurst =		0,
+	.bmAttributes =		0,
+	.wBytesPerInterval =	0,
+};
+
+static struct usb_descriptor_header *ss_loopback_descs[] = {
+	(struct usb_descriptor_header *) &loopback_intf,
+	(struct usb_descriptor_header *) &ss_loop_source_desc,
+	(struct usb_descriptor_header *) &ss_loop_source_comp_desc,
+	(struct usb_descriptor_header *) &ss_loop_sink_desc,
+	(struct usb_descriptor_header *) &ss_loop_sink_comp_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 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;
+	int ret;
+
+	/* allocate interface ID(s) */
+	id = usb_interface_id(c, f);
+	if (id < 0)
+		return id;
+	loopback_intf.bInterfaceNumber = id;
+
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+	strings_loopback[0].id = id;
+	loopback_intf.iInterface = id;
+
+	/* allocate endpoints */
+
+	loop->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_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->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_sink_desc);
+	if (!loop->out_ep)
+		goto autoconf_fail;
+
+	/* support high speed hardware */
+	hs_loop_source_desc.bEndpointAddress =
+		fs_loop_source_desc.bEndpointAddress;
+	hs_loop_sink_desc.bEndpointAddress = fs_loop_sink_desc.bEndpointAddress;
+
+	/* support super speed hardware */
+	ss_loop_source_desc.bEndpointAddress =
+		fs_loop_source_desc.bEndpointAddress;
+	ss_loop_sink_desc.bEndpointAddress = fs_loop_sink_desc.bEndpointAddress;
+
+	ret = usb_assign_descriptors(f, fs_loopback_descs, hs_loopback_descs,
+			ss_loopback_descs, ss_loopback_descs);
+	if (ret)
+		return ret;
+
+	DBG(cdev, "%s speed %s: IN/%s, OUT/%s\n",
+	    (gadget_is_superspeed(c->cdev->gadget) ? "super" :
+	     (gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full")),
+			f->name, loop->in_ep->name, loop->out_ep->name);
+	return 0;
+}
+
+static void lb_free_func(struct usb_function *f)
+{
+	struct f_lb_opts *opts;
+
+	opts = container_of(f->fi, struct f_lb_opts, func_inst);
+
+	mutex_lock(&opts->lock);
+	opts->refcnt--;
+	mutex_unlock(&opts->lock);
+
+	usb_free_all_descriptors(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) {
+			/*
+			 * We received some data from the host so let's
+			 * queue it so host can read the from our in ep
+			 */
+			struct usb_request *in_req = req->context;
+
+			in_req->zero = (req->actual < req->length);
+			in_req->length = req->actual;
+			ep = loop->in_ep;
+			req = in_req;
+		} else {
+			/*
+			 * We have just looped back a bunch of data
+			 * to host. Now let's wait for some more data.
+			 */
+			req = req->context;
+			ep = loop->out_ep;
+		}
+
+		/* queue the buffer back to host or for next bunch of data */
+		status = usb_ep_queue(ep, req, GFP_ATOMIC);
+		if (status == 0) {
+			return;
+		} else {
+			ERROR(cdev, "Unable to loop back buffer to %s: %d\n",
+			      ep->name, status);
+			goto free_req;
+		}
+
+		/* "should never get here" */
+	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_req:
+		usb_ep_free_request(ep == loop->in_ep ?
+				    loop->out_ep : loop->in_ep,
+				    req->context);
+		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, NULL, NULL);
+	VDBG(cdev, "%s disabled\n", loop->function.name);
+}
+
+static inline struct usb_request *lb_alloc_ep_req(struct usb_ep *ep, int len)
+{
+	return alloc_ep_req(ep, len);
+}
+
+static int alloc_requests(struct usb_composite_dev *cdev,
+			  struct f_loopback *loop)
+{
+	struct usb_request *in_req, *out_req;
+	int i;
+	int result = 0;
+
+	/*
+	 * allocate a bunch of read buffers and queue them all at once.
+	 * we buffer at most 'qlen' transfers; We allocate buffers only
+	 * for out transfer and reuse them in IN transfers to implement
+	 * our loopback functionality
+	 */
+	for (i = 0; i < loop->qlen && result == 0; i++) {
+		result = -ENOMEM;
+
+		in_req = usb_ep_alloc_request(loop->in_ep, GFP_ATOMIC);
+		if (!in_req)
+			goto fail;
+
+		out_req = lb_alloc_ep_req(loop->out_ep, loop->buflen);
+		if (!out_req)
+			goto fail_in;
+
+		in_req->complete = loopback_complete;
+		out_req->complete = loopback_complete;
+
+		in_req->buf = out_req->buf;
+		/* length will be set in complete routine */
+		in_req->context = out_req;
+		out_req->context = in_req;
+
+		result = usb_ep_queue(loop->out_ep, out_req, GFP_ATOMIC);
+		if (result) {
+			ERROR(cdev, "%s queue req --> %d\n",
+					loop->out_ep->name, result);
+			goto fail_out;
+		}
+	}
+
+	return 0;
+
+fail_out:
+	free_ep_req(loop->out_ep, out_req);
+fail_in:
+	usb_ep_free_request(loop->in_ep, in_req);
+fail:
+	return result;
+}
+
+static int enable_endpoint(struct usb_composite_dev *cdev,
+			   struct f_loopback *loop, struct usb_ep *ep)
+{
+	int					result;
+
+	result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
+	if (result)
+		goto out;
+
+	result = usb_ep_enable(ep);
+	if (result < 0)
+		goto out;
+	ep->driver_data = loop;
+	result = 0;
+
+out:
+	return result;
+}
+
+static int
+enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
+{
+	int					result = 0;
+
+	result = enable_endpoint(cdev, loop, loop->in_ep);
+	if (result)
+		goto out;
+
+	result = enable_endpoint(cdev, loop, loop->out_ep);
+	if (result)
+		goto disable_in;
+
+	result = alloc_requests(cdev, loop);
+	if (result)
+		goto disable_out;
+
+	DBG(cdev, "%s enabled\n", loop->function.name);
+	return 0;
+
+disable_out:
+	usb_ep_disable(loop->out_ep);
+disable_in:
+	usb_ep_disable(loop->in_ep);
+out:
+	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 */
+	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 struct usb_function *loopback_alloc(struct usb_function_instance *fi)
+{
+	struct f_loopback	*loop;
+	struct f_lb_opts	*lb_opts;
+
+	loop = kzalloc(sizeof *loop, GFP_KERNEL);
+	if (!loop)
+		return ERR_PTR(-ENOMEM);
+
+	lb_opts = container_of(fi, struct f_lb_opts, func_inst);
+
+	mutex_lock(&lb_opts->lock);
+	lb_opts->refcnt++;
+	mutex_unlock(&lb_opts->lock);
+
+	loop->buflen = lb_opts->bulk_buflen;
+	loop->qlen = lb_opts->qlen;
+	if (!loop->qlen)
+		loop->qlen = 32;
+
+	loop->function.name = "loopback";
+	loop->function.bind = loopback_bind;
+	loop->function.set_alt = loopback_set_alt;
+	loop->function.disable = loopback_disable;
+	loop->function.strings = loopback_strings;
+
+	loop->function.free_func = lb_free_func;
+
+	return &loop->function;
+}
+
+static inline struct f_lb_opts *to_f_lb_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_lb_opts,
+			    func_inst.group);
+}
+
+static void lb_attr_release(struct config_item *item)
+{
+	struct f_lb_opts *lb_opts = to_f_lb_opts(item);
+
+	usb_put_function_instance(&lb_opts->func_inst);
+}
+
+static struct configfs_item_operations lb_item_ops = {
+	.release		= lb_attr_release,
+};
+
+static ssize_t f_lb_opts_qlen_show(struct config_item *item, char *page)
+{
+	struct f_lb_opts *opts = to_f_lb_opts(item);
+	int result;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%d\n", opts->qlen);
+	mutex_unlock(&opts->lock);
+
+	return result;
+}
+
+static ssize_t f_lb_opts_qlen_store(struct config_item *item,
+				    const char *page, size_t len)
+{
+	struct f_lb_opts *opts = to_f_lb_opts(item);
+	int ret;
+	u32 num;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	ret = kstrtou32(page, 0, &num);
+	if (ret)
+		goto end;
+
+	opts->qlen = num;
+	ret = len;
+end:
+	mutex_unlock(&opts->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(f_lb_opts_, qlen);
+
+static ssize_t f_lb_opts_bulk_buflen_show(struct config_item *item, char *page)
+{
+	struct f_lb_opts *opts = to_f_lb_opts(item);
+	int result;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%d\n", opts->bulk_buflen);
+	mutex_unlock(&opts->lock);
+
+	return result;
+}
+
+static ssize_t f_lb_opts_bulk_buflen_store(struct config_item *item,
+				    const char *page, size_t len)
+{
+	struct f_lb_opts *opts = to_f_lb_opts(item);
+	int ret;
+	u32 num;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	ret = kstrtou32(page, 0, &num);
+	if (ret)
+		goto end;
+
+	opts->bulk_buflen = num;
+	ret = len;
+end:
+	mutex_unlock(&opts->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(f_lb_opts_, bulk_buflen);
+
+static struct configfs_attribute *lb_attrs[] = {
+	&f_lb_opts_attr_qlen,
+	&f_lb_opts_attr_bulk_buflen,
+	NULL,
+};
+
+static const struct config_item_type lb_func_type = {
+	.ct_item_ops    = &lb_item_ops,
+	.ct_attrs	= lb_attrs,
+	.ct_owner       = THIS_MODULE,
+};
+
+static void lb_free_instance(struct usb_function_instance *fi)
+{
+	struct f_lb_opts *lb_opts;
+
+	lb_opts = container_of(fi, struct f_lb_opts, func_inst);
+	kfree(lb_opts);
+}
+
+static struct usb_function_instance *loopback_alloc_instance(void)
+{
+	struct f_lb_opts *lb_opts;
+
+	lb_opts = kzalloc(sizeof(*lb_opts), GFP_KERNEL);
+	if (!lb_opts)
+		return ERR_PTR(-ENOMEM);
+	mutex_init(&lb_opts->lock);
+	lb_opts->func_inst.free_func_inst = lb_free_instance;
+	lb_opts->bulk_buflen = GZERO_BULK_BUFLEN;
+	lb_opts->qlen = GZERO_QLEN;
+
+	config_group_init_type_name(&lb_opts->func_inst.group, "",
+				    &lb_func_type);
+
+	return  &lb_opts->func_inst;
+}
+DECLARE_USB_FUNCTION(Loopback, loopback_alloc_instance, loopback_alloc);
+
+int __init lb_modinit(void)
+{
+	return usb_function_register(&Loopbackusb_func);
+}
+
+void __exit lb_modexit(void)
+{
+	usb_function_unregister(&Loopbackusb_func);
+}
+
+MODULE_LICENSE("GPL");