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  */
otg_get_transceiver(void)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  */
otg_put_transceiver(struct otg_transceiver * x)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  */
otg_set_transceiver(struct otg_transceiver * x)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 
otg_state_string(enum usb_otg_state state)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);
103