On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:
[mmotm.git] / drivers / usb / otg / otg.c
blob0a43a7db750f6dc445ea4fedc771722dd07a02e3
1 /*
2 * otg.c -- USB OTG utility code
4 * Copyright (C) 2004 Texas Instruments
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.
12 #include <linux/kernel.h>
13 #include <linux/device.h>
15 #include <linux/usb/otg.h>
17 static struct otg_transceiver *xceiv;
19 /**
20 * otg_get_transceiver - find the (single) OTG transceiver
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.
26 * For use by USB host and peripheral drivers.
28 struct otg_transceiver *otg_get_transceiver(void)
30 if (xceiv)
31 get_device(xceiv->dev);
32 return xceiv;
34 EXPORT_SYMBOL(otg_get_transceiver);
36 /**
37 * otg_put_transceiver - release the (single) OTG transceiver
38 * @x: the transceiver returned by otg_get_transceiver()
40 * Releases a refcount the caller received from otg_get_transceiver().
42 * For use by USB host and peripheral drivers.
44 void otg_put_transceiver(struct otg_transceiver *x)
46 if (x)
47 put_device(x->dev);
49 EXPORT_SYMBOL(otg_put_transceiver);
51 /**
52 * otg_set_transceiver - declare the (single) OTG transceiver
53 * @x: the USB OTG transceiver to be used; or NULL
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.
59 int otg_set_transceiver(struct otg_transceiver *x)
61 if (xceiv && x)
62 return -EBUSY;
63 xceiv = x;
64 return 0;
66 EXPORT_SYMBOL(otg_set_transceiver);