1/*
2 * otg-wakelock.c
3 *
4 * Copyright (C) 2011 Google, Inc.
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 */
16
17#include <linux/kernel.h>
18#include <linux/device.h>
19#include <linux/err.h>
20#include <linux/module.h>
21#include <linux/notifier.h>
22#include <linux/wakelock.h>
23#include <linux/spinlock.h>
24#include <linux/usb/otg.h>
25
26#define TEMPORARY_HOLD_TIME	2000
27
28static bool enabled = true;
29static struct usb_phy *otgwl_xceiv;
30static struct notifier_block otgwl_nb;
31
32/*
33 * otgwl_spinlock is held while the VBUS lock is grabbed or dropped and the
34 * held field is updated to match.
35 */
36
37static DEFINE_SPINLOCK(otgwl_spinlock);
38
39/*
40 * Only one lock, but since these 3 fields are associated with each other...
41 */
42
43struct otgwl_lock {
44	char name[40];
45	struct wake_lock wakelock;
46	bool held;
47};
48
49/*
50 * VBUS present lock.  Also used as a timed lock on charger
51 * connect/disconnect and USB host disconnect, to allow the system
52 * to react to the change in power.
53 */
54
55static struct otgwl_lock vbus_lock;
56
57static void otgwl_hold(struct otgwl_lock *lock)
58{
59	if (!lock->held) {
60		wake_lock(&lock->wakelock);
61		lock->held = true;
62	}
63}
64
65static void otgwl_temporary_hold(struct otgwl_lock *lock)
66{
67	wake_lock_timeout(&lock->wakelock,
68			  msecs_to_jiffies(TEMPORARY_HOLD_TIME));
69	lock->held = false;
70}
71
72static void otgwl_drop(struct otgwl_lock *lock)
73{
74	if (lock->held) {
75		wake_unlock(&lock->wakelock);
76		lock->held = false;
77	}
78}
79
80static void otgwl_handle_event(unsigned long event)
81{
82	unsigned long irqflags;
83
84	spin_lock_irqsave(&otgwl_spinlock, irqflags);
85
86	if (!enabled) {
87		otgwl_drop(&vbus_lock);
88		spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
89		return;
90	}
91
92	switch (event) {
93	case USB_EVENT_VBUS:
94	case USB_EVENT_ENUMERATED:
95		otgwl_hold(&vbus_lock);
96		break;
97
98	case USB_EVENT_NONE:
99	case USB_EVENT_ID:
100	case USB_EVENT_CHARGER:
101		otgwl_temporary_hold(&vbus_lock);
102		break;
103
104	default:
105		break;
106	}
107
108	spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
109}
110
111static int otgwl_otg_notifications(struct notifier_block *nb,
112				   unsigned long event, void *unused)
113{
114	otgwl_handle_event(event);
115	return NOTIFY_OK;
116}
117
118static int set_enabled(const char *val, const struct kernel_param *kp)
119{
120	int rv = param_set_bool(val, kp);
121
122	if (rv)
123		return rv;
124
125	if (otgwl_xceiv)
126		otgwl_handle_event(otgwl_xceiv->last_event);
127
128	return 0;
129}
130
131static struct kernel_param_ops enabled_param_ops = {
132	.set = set_enabled,
133	.get = param_get_bool,
134};
135
136module_param_cb(enabled, &enabled_param_ops, &enabled, 0644);
137MODULE_PARM_DESC(enabled, "enable wakelock when VBUS present");
138
139static int __init otg_wakelock_init(void)
140{
141	int ret;
142	struct usb_phy *phy;
143
144	phy = usb_get_phy(USB_PHY_TYPE_USB2);
145
146	if (IS_ERR(phy)) {
147		pr_err("%s: No USB transceiver found\n", __func__);
148		return PTR_ERR(phy);
149	}
150	otgwl_xceiv = phy;
151
152	snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s",
153		 dev_name(otgwl_xceiv->dev));
154	wake_lock_init(&vbus_lock.wakelock, WAKE_LOCK_SUSPEND,
155		       vbus_lock.name);
156
157	otgwl_nb.notifier_call = otgwl_otg_notifications;
158	ret = usb_register_notifier(otgwl_xceiv, &otgwl_nb);
159
160	if (ret) {
161		pr_err("%s: usb_register_notifier on transceiver %s"
162		       " failed\n", __func__,
163		       dev_name(otgwl_xceiv->dev));
164		otgwl_xceiv = NULL;
165		wake_lock_destroy(&vbus_lock.wakelock);
166		return ret;
167	}
168
169	otgwl_handle_event(otgwl_xceiv->last_event);
170	return ret;
171}
172
173late_initcall(otg_wakelock_init);
174