Todd Poynor | 21b36ea | 2011-07-01 17:19:56 -0700 | [diff] [blame^] | 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/notifier.h> |
| 20 | #include <linux/wakelock.h> |
| 21 | #include <linux/spinlock.h> |
| 22 | #include <linux/usb/otg.h> |
| 23 | |
| 24 | static bool enabled = true; |
| 25 | static struct otg_transceiver *otgwl_xceiv; |
| 26 | static struct notifier_block otgwl_nb; |
| 27 | |
| 28 | /* |
| 29 | * otgwl_spinlock is held while the VBUS lock is grabbed or dropped and the |
| 30 | * locked field is updated to match. |
| 31 | */ |
| 32 | |
| 33 | static DEFINE_SPINLOCK(otgwl_spinlock); |
| 34 | |
| 35 | /* |
| 36 | * Only one lock, but since these 3 fields are associated with each other... |
| 37 | */ |
| 38 | |
| 39 | struct otgwl_lock { |
| 40 | char name[40]; |
| 41 | struct wake_lock wakelock; |
| 42 | bool locked; |
| 43 | }; |
| 44 | |
| 45 | /* |
| 46 | * VBUS present lock. |
| 47 | */ |
| 48 | |
| 49 | static struct otgwl_lock vbus_lock; |
| 50 | |
| 51 | static void otgwl_grab(struct otgwl_lock *lock) |
| 52 | { |
| 53 | if (!lock->locked) { |
| 54 | wake_lock(&lock->wakelock); |
| 55 | lock->locked = true; |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | static void otgwl_drop(struct otgwl_lock *lock) |
| 60 | { |
| 61 | if (lock->locked) { |
| 62 | wake_unlock(&lock->wakelock); |
| 63 | lock->locked = false; |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | static int otgwl_otg_notifications(struct notifier_block *nb, |
| 68 | unsigned long event, void *unused) |
| 69 | { |
| 70 | unsigned long irqflags; |
| 71 | |
| 72 | if (!enabled) |
| 73 | return NOTIFY_OK; |
| 74 | |
| 75 | spin_lock_irqsave(&otgwl_spinlock, irqflags); |
| 76 | |
| 77 | switch (event) { |
| 78 | case USB_EVENT_VBUS: |
| 79 | case USB_EVENT_ENUMERATED: |
| 80 | otgwl_grab(&vbus_lock); |
| 81 | break; |
| 82 | |
| 83 | case USB_EVENT_NONE: |
| 84 | case USB_EVENT_ID: |
| 85 | case USB_EVENT_CHARGER: |
| 86 | otgwl_drop(&vbus_lock); |
| 87 | break; |
| 88 | |
| 89 | default: |
| 90 | break; |
| 91 | } |
| 92 | |
| 93 | spin_unlock_irqrestore(&otgwl_spinlock, irqflags); |
| 94 | return NOTIFY_OK; |
| 95 | } |
| 96 | |
| 97 | static void sync_with_xceiv_state(void) |
| 98 | { |
| 99 | if ((otgwl_xceiv->last_event == USB_EVENT_VBUS) || |
| 100 | (otgwl_xceiv->last_event == USB_EVENT_ENUMERATED)) |
| 101 | otgwl_grab(&vbus_lock); |
| 102 | else |
| 103 | otgwl_drop(&vbus_lock); |
| 104 | } |
| 105 | |
| 106 | static int init_for_xceiv(void) |
| 107 | { |
| 108 | int rv; |
| 109 | |
| 110 | if (!otgwl_xceiv) { |
| 111 | otgwl_xceiv = otg_get_transceiver(); |
| 112 | |
| 113 | if (!otgwl_xceiv) { |
| 114 | pr_err("%s: No OTG transceiver found\n", __func__); |
| 115 | return -ENODEV; |
| 116 | } |
| 117 | |
| 118 | snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s", |
| 119 | dev_name(otgwl_xceiv->dev)); |
| 120 | wake_lock_init(&vbus_lock.wakelock, WAKE_LOCK_SUSPEND, |
| 121 | vbus_lock.name); |
| 122 | |
| 123 | rv = otg_register_notifier(otgwl_xceiv, &otgwl_nb); |
| 124 | |
| 125 | if (rv) { |
| 126 | pr_err("%s: otg_register_notifier on transceiver %s" |
| 127 | " failed\n", __func__, |
| 128 | dev_name(otgwl_xceiv->dev)); |
| 129 | otgwl_xceiv = NULL; |
| 130 | wake_lock_destroy(&vbus_lock.wakelock); |
| 131 | return rv; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | return 0; |
| 136 | } |
| 137 | |
| 138 | static int set_enabled(const char *val, const struct kernel_param *kp) |
| 139 | { |
| 140 | unsigned long irqflags; |
| 141 | int rv = param_set_bool(val, kp); |
| 142 | |
| 143 | if (rv) |
| 144 | return rv; |
| 145 | |
| 146 | rv = init_for_xceiv(); |
| 147 | |
| 148 | if (rv) |
| 149 | return rv; |
| 150 | |
| 151 | spin_lock_irqsave(&otgwl_spinlock, irqflags); |
| 152 | |
| 153 | if (enabled) |
| 154 | sync_with_xceiv_state(); |
| 155 | else |
| 156 | otgwl_drop(&vbus_lock); |
| 157 | |
| 158 | spin_unlock_irqrestore(&otgwl_spinlock, irqflags); |
| 159 | return 0; |
| 160 | } |
| 161 | |
| 162 | static struct kernel_param_ops enabled_param_ops = { |
| 163 | .set = set_enabled, |
| 164 | .get = param_get_bool, |
| 165 | }; |
| 166 | |
| 167 | module_param_cb(enabled, &enabled_param_ops, &enabled, 0644); |
| 168 | MODULE_PARM_DESC(enabled, "enable wakelock when VBUS present"); |
| 169 | |
| 170 | static int __init otg_wakelock_init(void) |
| 171 | { |
| 172 | unsigned long irqflags; |
| 173 | |
| 174 | otgwl_nb.notifier_call = otgwl_otg_notifications; |
| 175 | |
| 176 | if (!init_for_xceiv()) { |
| 177 | spin_lock_irqsave(&otgwl_spinlock, irqflags); |
| 178 | |
| 179 | if (enabled) |
| 180 | sync_with_xceiv_state(); |
| 181 | |
| 182 | spin_unlock_irqrestore(&otgwl_spinlock, irqflags); |
| 183 | } else { |
| 184 | enabled = false; |
| 185 | } |
| 186 | |
| 187 | return 0; |
| 188 | } |
| 189 | |
| 190 | late_initcall(otg_wakelock_init); |