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/spinlock.h>
23 #include <linux/usb/otg.h>
24
25 #define TEMPORARY_HOLD_TIME 2000
26
27 static bool enabled = true;
28 static struct usb_phy *otgwl_xceiv;
29 static struct notifier_block otgwl_nb;
30
31 /*
32 * otgwl_spinlock is held while the VBUS lock is grabbed or dropped and the
33 * held field is updated to match.
34 */
35
36 static DEFINE_SPINLOCK(otgwl_spinlock);
37
38 /*
39 * Only one lock, but since these 3 fields are associated with each other...
40 */
41
42 struct otgwl_lock {
43 char name[40];
44 struct wakeup_source wakesrc;
45 bool held;
46 };
47
48 /*
49 * VBUS present lock. Also used as a timed lock on charger
50 * connect/disconnect and USB host disconnect, to allow the system
51 * to react to the change in power.
52 */
53
54 static struct otgwl_lock vbus_lock;
55
otgwl_hold(struct otgwl_lock * lock)56 static void otgwl_hold(struct otgwl_lock *lock)
57 {
58 if (!lock->held) {
59 __pm_stay_awake(&lock->wakesrc);
60 lock->held = true;
61 }
62 }
63
otgwl_temporary_hold(struct otgwl_lock * lock)64 static void otgwl_temporary_hold(struct otgwl_lock *lock)
65 {
66 __pm_wakeup_event(&lock->wakesrc, TEMPORARY_HOLD_TIME);
67 lock->held = false;
68 }
69
otgwl_drop(struct otgwl_lock * lock)70 static void otgwl_drop(struct otgwl_lock *lock)
71 {
72 if (lock->held) {
73 __pm_relax(&lock->wakesrc);
74 lock->held = false;
75 }
76 }
77
otgwl_handle_event(unsigned long event)78 static void otgwl_handle_event(unsigned long event)
79 {
80 unsigned long irqflags;
81
82 spin_lock_irqsave(&otgwl_spinlock, irqflags);
83
84 if (!enabled) {
85 otgwl_drop(&vbus_lock);
86 spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
87 return;
88 }
89
90 switch (event) {
91 case USB_EVENT_VBUS:
92 case USB_EVENT_ENUMERATED:
93 otgwl_hold(&vbus_lock);
94 break;
95
96 case USB_EVENT_NONE:
97 case USB_EVENT_ID:
98 case USB_EVENT_CHARGER:
99 otgwl_temporary_hold(&vbus_lock);
100 break;
101
102 default:
103 break;
104 }
105
106 spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
107 }
108
otgwl_otg_notifications(struct notifier_block * nb,unsigned long event,void * unused)109 static int otgwl_otg_notifications(struct notifier_block *nb,
110 unsigned long event, void *unused)
111 {
112 otgwl_handle_event(event);
113 return NOTIFY_OK;
114 }
115
set_enabled(const char * val,const struct kernel_param * kp)116 static int set_enabled(const char *val, const struct kernel_param *kp)
117 {
118 int rv = param_set_bool(val, kp);
119
120 if (rv)
121 return rv;
122
123 if (otgwl_xceiv)
124 otgwl_handle_event(otgwl_xceiv->last_event);
125
126 return 0;
127 }
128
129 static struct kernel_param_ops enabled_param_ops = {
130 .set = set_enabled,
131 .get = param_get_bool,
132 };
133
134 module_param_cb(enabled, &enabled_param_ops, &enabled, 0644);
135 MODULE_PARM_DESC(enabled, "enable wakelock when VBUS present");
136
otg_wakelock_init(void)137 static int __init otg_wakelock_init(void)
138 {
139 int ret;
140 struct usb_phy *phy;
141
142 phy = usb_get_phy(USB_PHY_TYPE_USB2);
143
144 if (IS_ERR(phy)) {
145 pr_err("%s: No USB transceiver found\n", __func__);
146 return PTR_ERR(phy);
147 }
148 otgwl_xceiv = phy;
149
150 snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s",
151 dev_name(otgwl_xceiv->dev));
152 wakeup_source_init(&vbus_lock.wakesrc, vbus_lock.name);
153
154 otgwl_nb.notifier_call = otgwl_otg_notifications;
155 ret = usb_register_notifier(otgwl_xceiv, &otgwl_nb);
156
157 if (ret) {
158 pr_err("%s: usb_register_notifier on transceiver %s"
159 " failed\n", __func__,
160 dev_name(otgwl_xceiv->dev));
161 otgwl_xceiv = NULL;
162 wakeup_source_trash(&vbus_lock.wakesrc);
163 return ret;
164 }
165
166 otgwl_handle_event(otgwl_xceiv->last_event);
167 return ret;
168 }
169
170 late_initcall(otg_wakelock_init);
171