f_loopback.c

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/*
 * 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.
 */

/* #define VERBOSE_DEBUG */

#include <linux/slab.h>
#include <linux/kernel.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_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),
};

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),
};

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 __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_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->in_ep->driver_data = cdev;    /* claim */

    loop->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_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_loop_source_desc.bEndpointAddress =
                fs_loop_source_desc.bEndpointAddress;
        hs_loop_sink_desc.bEndpointAddress =
                fs_loop_sink_desc.bEndpointAddress;
        f->hs_descriptors = hs_loopback_descs;
    }

    /* support super speed hardware */
    if (gadget_is_superspeed(c->cdev->gadget)) {
        ss_loop_source_desc.bEndpointAddress =
                fs_loop_source_desc.bEndpointAddress;
        ss_loop_sink_desc.bEndpointAddress =
                fs_loop_sink_desc.bEndpointAddress;
        f->ss_descriptors = ss_loopback_descs;
    }

    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
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, NULL, NULL);
    VDBG(cdev, "%s disabled\n", loop->function.name);
}

static int
enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
{
    int                 result = 0;
    struct usb_ep               *ep;
    struct usb_request          *req;
    unsigned                i;

    /* one endpoint writes data back IN to the host */
    ep = loop->in_ep;
    result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
    if (result)
        return result;
    result = usb_ep_enable(ep);
    if (result < 0)
        return result;
    ep->driver_data = loop;

    /* one endpoint just reads OUT packets */
    ep = loop->out_ep;
    result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
    if (result)
        goto fail0;

    result = usb_ep_enable(ep);
    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, 0);
        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,
    .bConfigurationValue = 2,
    .bmAttributes   = USB_CONFIG_ATT_SELFPOWER,
    /* .iConfiguration = DYNAMIC */
};

int __init loopback_add(struct usb_composite_dev *cdev, bool autoresume)
{
    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 autoresume for remote wakeup testing */
    if (autoresume)
        loopback_driver.bmAttributes |= USB_CONFIG_ATT_WAKEUP;

    /* 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, loopback_bind_config);
}