// 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 <linux/usb/func_utils.h>
#include "g_zero.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: IN/%s, OUT/%s\n",
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_DESCRIPTION("USB peripheral loopback configuration driver");
MODULE_LICENSE("GPL");
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