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/export.h>
  14 #include <linux/device.h>
  15
  16 #include <linux/usb/otg.h>
  17
  18 static struct otg_transceiver *xceiv;
  19
  20 /**
  21  * otg_get_transceiver - find the (single) OTG transceiver
  22  *
  23  * Returns the transceiver driver, after getting a refcount to it; or
  24  * null if there is no such transceiver.  The caller is responsible for
  25  * calling otg_put_transceiver() to release that count.
  26  *
  27  * For use by USB host and peripheral drivers.
  28  */
  29 struct otg_transceiver *otg_get_transceiver(void)
  30 {
  31         if (xceiv)
  32                 get_device(xceiv->dev);
  33         return xceiv;
  34 }
  35 EXPORT_SYMBOL(otg_get_transceiver);
  36
  37 /**
  38  * otg_put_transceiver - release the (single) OTG transceiver
  39  * @x: the transceiver returned by otg_get_transceiver()
  40  *
  41  * Releases a refcount the caller received from otg_get_transceiver().
  42  *
  43  * For use by USB host and peripheral drivers.
  44  */
  45 void otg_put_transceiver(struct otg_transceiver *x)
  46 {
  47         if (x)
  48                 put_device(x->dev);
  49 }
  50 EXPORT_SYMBOL(otg_put_transceiver);
  51
  52 /**
  53  * otg_set_transceiver - declare the (single) OTG transceiver
  54  * @x: the USB OTG transceiver to be used; or NULL
  55  *
  56  * This call is exclusively for use by transceiver drivers, which
  57  * coordinate the activities of drivers for host and peripheral
  58  * controllers, and in some cases for VBUS current regulation.
  59  */
  60 int otg_set_transceiver(struct otg_transceiver *x)
  61 {
  62         if (xceiv && x)
  63                 return -EBUSY;
  64         xceiv = x;
  65         return 0;
  66 }
  67 EXPORT_SYMBOL(otg_set_transceiver);
  68
  69 const char *otg_state_string(enum usb_otg_state state)
  70 {
  71         switch (state) {
  72         case OTG_STATE_A_IDLE:
  73                 return "a_idle";
  74         case OTG_STATE_A_WAIT_VRISE:
  75                 return "a_wait_vrise";
  76         case OTG_STATE_A_WAIT_BCON:
  77                 return "a_wait_bcon";
  78         case OTG_STATE_A_HOST:
  79                 return "a_host";
  80         case OTG_STATE_A_SUSPEND:
  81                 return "a_suspend";
  82         case OTG_STATE_A_PERIPHERAL:
  83                 return "a_peripheral";
  84         case OTG_STATE_A_WAIT_VFALL:
  85                 return "a_wait_vfall";
  86         case OTG_STATE_A_VBUS_ERR:
  87                 return "a_vbus_err";
  88         case OTG_STATE_B_IDLE:
  89                 return "b_idle";
  90         case OTG_STATE_B_SRP_INIT:
  91                 return "b_srp_init";
  92         case OTG_STATE_B_PERIPHERAL:
  93                 return "b_peripheral";
  94         case OTG_STATE_B_WAIT_ACON:
  95                 return "b_wait_acon";
  96         case OTG_STATE_B_HOST:
  97                 return "b_host";
  98         default:
  99                 return "UNDEFINED";
 100         }
 101 }
 102 EXPORT_SYMBOL(otg_state_string);