drivers/input/keyreset.c

   1 /* drivers/input/keyreset.c
   2  *
   3  * Copyright (C) 2008 Google, Inc.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <linux/input.h>
  17 #include <linux/keyreset.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/reboot.h>
  21 #include <linux/sched.h>
  22 #include <linux/slab.h>
  23 #include <linux/syscalls.h>
  24
  25
  26 struct keyreset_state {
  27         struct input_handler input_handler;
  28         unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];
  29         unsigned long upbit[BITS_TO_LONGS(KEY_CNT)];
  30         unsigned long key[BITS_TO_LONGS(KEY_CNT)];
  31         spinlock_t lock;
  32         int key_down_target;
  33         int key_down;
  34         int key_up;
  35         int restart_disabled;
  36         int (*reset_fn)(void);
  37 };
  38
  39 int restart_requested;
  40 static void deferred_restart(struct work_struct *dummy)
  41 {
  42         restart_requested = 2;
  43         sys_sync();
  44         restart_requested = 3;
  45         kernel_restart(NULL);
  46 }
  47 static DECLARE_WORK(restart_work, deferred_restart);
  48
  49 static void keyreset_event(struct input_handle *handle, unsigned int type,
  50                            unsigned int code, int value)
  51 {
  52         unsigned long flags;
  53         struct keyreset_state *state = handle->private;
  54
  55         if (type != EV_KEY)
  56                 return;
  57
  58         if (code >= KEY_MAX)
  59                 return;
  60
  61         if (!test_bit(code, state->keybit))
  62                 return;
  63
  64         spin_lock_irqsave(&state->lock, flags);
  65         if (!test_bit(code, state->key) == !value)
  66                 goto done;
  67         __change_bit(code, state->key);
  68         if (test_bit(code, state->upbit)) {
  69                 if (value) {
  70                         state->restart_disabled = 1;
  71                         state->key_up++;
  72                 } else
  73                         state->key_up--;
  74         } else {
  75                 if (value)
  76                         state->key_down++;
  77                 else
  78                         state->key_down--;
  79         }
  80         if (state->key_down == 0 && state->key_up == 0)
  81                 state->restart_disabled = 0;
  82
  83         pr_debug("reset key changed %d %d new state %d-%d-%d\n", code, value,
  84                  state->key_down, state->key_up, state->restart_disabled);
  85
  86         if (value && !state->restart_disabled &&
  87             state->key_down == state->key_down_target) {
  88                 state->restart_disabled = 1;
  89                 if (restart_requested)
  90                         panic("keyboard reset failed, %d", restart_requested);
  91                 if (state->reset_fn) {
  92                         restart_requested = state->reset_fn();
  93                 } else {
  94                         pr_info("keyboard reset\n");
  95                         schedule_work(&restart_work);
  96                         restart_requested = 1;
  97                 }
  98         }
  99 done:
 100         spin_unlock_irqrestore(&state->lock, flags);
 101 }
 102
 103 static int keyreset_connect(struct input_handler *handler,
 104                                           struct input_dev *dev,
 105                                           const struct input_device_id *id)
 106 {
 107         int i;
 108         int ret;
 109         struct input_handle *handle;
 110         struct keyreset_state *state =
 111                 container_of(handler, struct keyreset_state, input_handler);
 112
 113         for (i = 0; i < KEY_MAX; i++) {
 114                 if (test_bit(i, state->keybit) && test_bit(i, dev->keybit))
 115                         break;
 116         }
 117         if (i == KEY_MAX)
 118                 return -ENODEV;
 119
 120         handle = kzalloc(sizeof(*handle), GFP_KERNEL);
 121         if (!handle)
 122                 return -ENOMEM;
 123
 124         handle->dev = dev;
 125         handle->handler = handler;
 126         handle->name = "keyreset";
 127         handle->private = state;
 128
 129         ret = input_register_handle(handle);
 130         if (ret)
 131                 goto err_input_register_handle;
 132
 133         ret = input_open_device(handle);
 134         if (ret)
 135                 goto err_input_open_device;
 136
 137         pr_info("using input dev %s for key reset\n", dev->name);
 138
 139         return 0;
 140
 141 err_input_open_device:
 142         input_unregister_handle(handle);
 143 err_input_register_handle:
 144         kfree(handle);
 145         return ret;
 146 }
 147
 148 static void keyreset_disconnect(struct input_handle *handle)
 149 {
 150         input_close_device(handle);
 151         input_unregister_handle(handle);
 152         kfree(handle);
 153 }
 154
 155 static const struct input_device_id keyreset_ids[] = {
 156         {
 157                 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
 158                 .evbit = { BIT_MASK(EV_KEY) },
 159         },
 160         { },
 161 };
 162 MODULE_DEVICE_TABLE(input, keyreset_ids);
 163
 164 static int keyreset_probe(struct platform_device *pdev)
 165 {
 166         int ret;
 167         int key, *keyp;
 168         struct keyreset_state *state;
 169         struct keyreset_platform_data *pdata = pdev->dev.platform_data;
 170
 171         if (!pdata)
 172                 return -EINVAL;
 173
 174         state = kzalloc(sizeof(*state), GFP_KERNEL);
 175         if (!state)
 176                 return -ENOMEM;
 177
 178         spin_lock_init(&state->lock);
 179         keyp = pdata->keys_down;
 180         while ((key = *keyp++)) {
 181                 if (key >= KEY_MAX)
 182                         continue;
 183                 state->key_down_target++;
 184                 __set_bit(key, state->keybit);
 185         }
 186         if (pdata->keys_up) {
 187                 keyp = pdata->keys_up;
 188                 while ((key = *keyp++)) {
 189                         if (key >= KEY_MAX)
 190                                 continue;
 191                         __set_bit(key, state->keybit);
 192                         __set_bit(key, state->upbit);
 193                 }
 194         }
 195
 196         if (pdata->reset_fn)
 197                 state->reset_fn = pdata->reset_fn;
 198
 199         state->input_handler.event = keyreset_event;
 200         state->input_handler.connect = keyreset_connect;
 201         state->input_handler.disconnect = keyreset_disconnect;
 202         state->input_handler.name = KEYRESET_NAME;
 203         state->input_handler.id_table = keyreset_ids;
 204         ret = input_register_handler(&state->input_handler);
 205         if (ret) {
 206                 kfree(state);
 207                 return ret;
 208         }
 209         platform_set_drvdata(pdev, state);
 210         return 0;
 211 }
 212
 213 int keyreset_remove(struct platform_device *pdev)
 214 {
 215         struct keyreset_state *state = platform_get_drvdata(pdev);
 216         input_unregister_handler(&state->input_handler);
 217         kfree(state);
 218         return 0;
 219 }
 220
 221
 222 struct platform_driver keyreset_driver = {
 223         .driver.name = KEYRESET_NAME,
 224         .probe = keyreset_probe,
 225         .remove = keyreset_remove,
 226 };
 227
 228 static int __init keyreset_init(void)
 229 {
 230         return platform_driver_register(&keyreset_driver);
 231 }
 232
 233 static void __exit keyreset_exit(void)
 234 {
 235         return platform_driver_unregister(&keyreset_driver);
 236 }
 237
 238 module_init(keyreset_init);
 239 module_exit(keyreset_exit);