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