LXR linux/drivers/usb/otg/otg.c

   1/*
   2 * otg.c -- USB OTG utility code
   3 *
   4 * Copyright (C) 2004 Texas Instruments
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 */
  11
  12#include <linux/kernel.h>
  13#include <linux/device.h>
  14
  15#include <linux/usb/otg.h>
  16
  17static struct otg_transceiver *xceiv;
  18
  19/**
  20 * otg_get_transceiver - find the (single) OTG transceiver
  21 *
  22 * Returns the transceiver driver, after getting a refcount to it; or
  23 * null if there is no such transceiver.  The caller is responsible for
  24 * calling otg_put_transceiver() to release that count.
  25 *
  26 * For use by USB host and peripheral drivers.
  27 */
  28struct otg_transceiver *otg_get_transceiver(void)
  29{
  30        if (xceiv)
  31                get_device(xceiv->dev);
  32        return xceiv;
  33}
  34EXPORT_SYMBOL(otg_get_transceiver);
  35
  36/**
  37 * otg_put_transceiver - release the (single) OTG transceiver
  38 * @x: the transceiver returned by otg_get_transceiver()
  39 *
  40 * Releases a refcount the caller received from otg_get_transceiver().
  41 *
  42 * For use by USB host and peripheral drivers.
  43 */
  44void otg_put_transceiver(struct otg_transceiver *x)
  45{
  46        if (x)
  47                put_device(x->dev);
  48}
  49EXPORT_SYMBOL(otg_put_transceiver);
  50
  51/**
  52 * otg_set_transceiver - declare the (single) OTG transceiver
  53 * @x: the USB OTG transceiver to be used; or NULL
  54 *
  55 * This call is exclusively for use by transceiver drivers, which
  56 * coordinate the activities of drivers for host and peripheral
  57 * controllers, and in some cases for VBUS current regulation.
  58 */
  59int otg_set_transceiver(struct otg_transceiver *x)
  60{
  61        if (xceiv && x)
  62                return -EBUSY;
  63        xceiv = x;
  64        return 0;
  65}
  66EXPORT_SYMBOL(otg_set_transceiver);
  67