drivers/input/serio/serio_raw.c

   1 /*
   2  * Raw serio device providing access to a raw byte stream from underlying
   3  * serio port. Closely emulates behavior of pre-2.6 /dev/psaux device
   4  *
   5  * Copyright (c) 2004 Dmitry Torokhov
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published by
   9  * the Free Software Foundation.
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/poll.h>
  14 #include <linux/module.h>
  15 #include <linux/serio.h>
  16 #include <linux/init.h>
  17 #include <linux/major.h>
  18 #include <linux/device.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/wait.h>
  21 #include <linux/mutex.h>
  22
  23 #define DRIVER_DESC     "Raw serio driver"
  24
  25 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
  26 MODULE_DESCRIPTION(DRIVER_DESC);
  27 MODULE_LICENSE("GPL");
  28
  29 #define SERIO_RAW_QUEUE_LEN     64
  30 struct serio_raw {
  31         unsigned char queue[SERIO_RAW_QUEUE_LEN];
  32         unsigned int tail, head;
  33
  34         char name[16];
  35         unsigned int refcnt;
  36         struct serio *serio;
  37         struct miscdevice dev;
  38         wait_queue_head_t wait;
  39         struct list_head list;
  40         struct list_head node;
  41 };
  42
  43 struct serio_raw_list {
  44         struct fasync_struct *fasync;
  45         struct serio_raw *serio_raw;
  46         struct list_head node;
  47 };
  48
  49 static DEFINE_MUTEX(serio_raw_mutex);
  50 static LIST_HEAD(serio_raw_list);
  51 static unsigned int serio_raw_no;
  52
  53 /*********************************************************************
  54  *             Interface with userspace (file operations)            *
  55  *********************************************************************/
  56
  57 static int serio_raw_fasync(int fd, struct file *file, int on)
  58 {
  59         struct serio_raw_list *list = file->private_data;
  60         int retval;
  61
  62         retval = fasync_helper(fd, file, on, &list->fasync);
  63         return retval < 0 ? retval : 0;
  64 }
  65
  66 static struct serio_raw *serio_raw_locate(int minor)
  67 {
  68         struct serio_raw *serio_raw;
  69
  70         list_for_each_entry(serio_raw, &serio_raw_list, node) {
  71                 if (serio_raw->dev.minor == minor)
  72                         return serio_raw;
  73         }
  74
  75         return NULL;
  76 }
  77
  78 static int serio_raw_open(struct inode *inode, struct file *file)
  79 {
  80         struct serio_raw *serio_raw;
  81         struct serio_raw_list *list;
  82         int retval = 0;
  83
  84         retval = mutex_lock_interruptible(&serio_raw_mutex);
  85         if (retval)
  86                 return retval;
  87
  88         if (!(serio_raw = serio_raw_locate(iminor(inode)))) {
  89                 retval = -ENODEV;
  90                 goto out;
  91         }
  92
  93         if (!serio_raw->serio) {
  94                 retval = -ENODEV;
  95                 goto out;
  96         }
  97
  98         if (!(list = kzalloc(sizeof(struct serio_raw_list), GFP_KERNEL))) {
  99                 retval = -ENOMEM;
 100                 goto out;
 101         }
 102
 103         list->serio_raw = serio_raw;
 104         file->private_data = list;
 105
 106         serio_raw->refcnt++;
 107         list_add_tail(&list->node, &serio_raw->list);
 108
 109 out:
 110         mutex_unlock(&serio_raw_mutex);
 111         return retval;
 112 }
 113
 114 static int serio_raw_cleanup(struct serio_raw *serio_raw)
 115 {
 116         if (--serio_raw->refcnt == 0) {
 117                 misc_deregister(&serio_raw->dev);
 118                 list_del_init(&serio_raw->node);
 119                 kfree(serio_raw);
 120
 121                 return 1;
 122         }
 123
 124         return 0;
 125 }
 126
 127 static int serio_raw_release(struct inode *inode, struct file *file)
 128 {
 129         struct serio_raw_list *list = file->private_data;
 130         struct serio_raw *serio_raw = list->serio_raw;
 131
 132         mutex_lock(&serio_raw_mutex);
 133
 134         serio_raw_fasync(-1, file, 0);
 135         serio_raw_cleanup(serio_raw);
 136
 137         mutex_unlock(&serio_raw_mutex);
 138         return 0;
 139 }
 140
 141 static int serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
 142 {
 143         unsigned long flags;
 144         int empty;
 145
 146         spin_lock_irqsave(&serio_raw->serio->lock, flags);
 147
 148         empty = serio_raw->head == serio_raw->tail;
 149         if (!empty) {
 150                 *c = serio_raw->queue[serio_raw->tail];
 151                 serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
 152         }
 153
 154         spin_unlock_irqrestore(&serio_raw->serio->lock, flags);
 155
 156         return !empty;
 157 }
 158
 159 static ssize_t serio_raw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 160 {
 161         struct serio_raw_list *list = file->private_data;
 162         struct serio_raw *serio_raw = list->serio_raw;
 163         char uninitialized_var(c);
 164         ssize_t retval = 0;
 165
 166         if (!serio_raw->serio)
 167                 return -ENODEV;
 168
 169         if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
 170                 return -EAGAIN;
 171
 172         retval = wait_event_interruptible(list->serio_raw->wait,
 173                                           serio_raw->head != serio_raw->tail || !serio_raw->serio);
 174         if (retval)
 175                 return retval;
 176
 177         if (!serio_raw->serio)
 178                 return -ENODEV;
 179
 180         while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
 181                 if (put_user(c, buffer++))
 182                         return -EFAULT;
 183                 retval++;
 184         }
 185
 186         return retval;
 187 }
 188
 189 static ssize_t serio_raw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 190 {
 191         struct serio_raw_list *list = file->private_data;
 192         ssize_t written = 0;
 193         int retval;
 194         unsigned char c;
 195
 196         retval = mutex_lock_interruptible(&serio_raw_mutex);
 197         if (retval)
 198                 return retval;
 199
 200         if (!list->serio_raw->serio) {
 201                 retval = -ENODEV;
 202                 goto out;
 203         }
 204
 205         if (count > 32)
 206                 count = 32;
 207
 208         while (count--) {
 209                 if (get_user(c, buffer++)) {
 210                         retval = -EFAULT;
 211                         goto out;
 212                 }
 213                 if (serio_write(list->serio_raw->serio, c)) {
 214                         retval = -EIO;
 215                         goto out;
 216                 }
 217                 written++;
 218         };
 219
 220 out:
 221         mutex_unlock(&serio_raw_mutex);
 222         return written;
 223 }
 224
 225 static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
 226 {
 227         struct serio_raw_list *list = file->private_data;
 228
 229         poll_wait(file, &list->serio_raw->wait, wait);
 230
 231         if (list->serio_raw->head != list->serio_raw->tail)
 232                 return POLLIN | POLLRDNORM;
 233
 234         return 0;
 235 }
 236
 237 static const struct file_operations serio_raw_fops = {
 238         .owner =        THIS_MODULE,
 239         .open =         serio_raw_open,
 240         .release =      serio_raw_release,
 241         .read =         serio_raw_read,
 242         .write =        serio_raw_write,
 243         .poll =         serio_raw_poll,
 244         .fasync =       serio_raw_fasync,
 245 };
 246
 247
 248 /*********************************************************************
 249  *                   Interface with serio port                       *
 250  *********************************************************************/
 251
 252 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
 253                                         unsigned int dfl)
 254 {
 255         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 256         struct serio_raw_list *list;
 257         unsigned int head = serio_raw->head;
 258
 259         /* we are holding serio->lock here so we are prootected */
 260         serio_raw->queue[head] = data;
 261         head = (head + 1) % SERIO_RAW_QUEUE_LEN;
 262         if (likely(head != serio_raw->tail)) {
 263                 serio_raw->head = head;
 264                 list_for_each_entry(list, &serio_raw->list, node)
 265                         kill_fasync(&list->fasync, SIGIO, POLL_IN);
 266                 wake_up_interruptible(&serio_raw->wait);
 267         }
 268
 269         return IRQ_HANDLED;
 270 }
 271
 272 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
 273 {
 274         struct serio_raw *serio_raw;
 275         int err;
 276
 277         if (!(serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL))) {
 278                 printk(KERN_ERR "serio_raw.c: can't allocate memory for a device\n");
 279                 return -ENOMEM;
 280         }
 281
 282         mutex_lock(&serio_raw_mutex);
 283
 284         snprintf(serio_raw->name, sizeof(serio_raw->name), "serio_raw%d", serio_raw_no++);
 285         serio_raw->refcnt = 1;
 286         serio_raw->serio = serio;
 287         INIT_LIST_HEAD(&serio_raw->list);
 288         init_waitqueue_head(&serio_raw->wait);
 289
 290         serio_set_drvdata(serio, serio_raw);
 291
 292         err = serio_open(serio, drv);
 293         if (err)
 294                 goto out_free;
 295
 296         list_add_tail(&serio_raw->node, &serio_raw_list);
 297
 298         serio_raw->dev.minor = PSMOUSE_MINOR;
 299         serio_raw->dev.name = serio_raw->name;
 300         serio_raw->dev.parent = &serio->dev;
 301         serio_raw->dev.fops = &serio_raw_fops;
 302
 303         err = misc_register(&serio_raw->dev);
 304         if (err) {
 305                 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
 306                 err = misc_register(&serio_raw->dev);
 307         }
 308
 309         if (err) {
 310                 printk(KERN_INFO "serio_raw: failed to register raw access device for %s\n",
 311                         serio->phys);
 312                 goto out_close;
 313         }
 314
 315         printk(KERN_INFO "serio_raw: raw access enabled on %s (%s, minor %d)\n",
 316                 serio->phys, serio_raw->name, serio_raw->dev.minor);
 317         goto out;
 318
 319 out_close:
 320         serio_close(serio);
 321         list_del_init(&serio_raw->node);
 322 out_free:
 323         serio_set_drvdata(serio, NULL);
 324         kfree(serio_raw);
 325 out:
 326         mutex_unlock(&serio_raw_mutex);
 327         return err;
 328 }
 329
 330 static int serio_raw_reconnect(struct serio *serio)
 331 {
 332         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 333         struct serio_driver *drv = serio->drv;
 334
 335         if (!drv || !serio_raw) {
 336                 printk(KERN_DEBUG "serio_raw: reconnect request, but serio is disconnected, ignoring...\n");
 337                 return -1;
 338         }
 339
 340         /*
 341          * Nothing needs to be done here, we just need this method to
 342          * keep the same device.
 343          */
 344         return 0;
 345 }
 346
 347 static void serio_raw_disconnect(struct serio *serio)
 348 {
 349         struct serio_raw *serio_raw;
 350
 351         mutex_lock(&serio_raw_mutex);
 352
 353         serio_raw = serio_get_drvdata(serio);
 354
 355         serio_close(serio);
 356         serio_set_drvdata(serio, NULL);
 357
 358         serio_raw->serio = NULL;
 359         if (!serio_raw_cleanup(serio_raw))
 360                 wake_up_interruptible(&serio_raw->wait);
 361
 362         mutex_unlock(&serio_raw_mutex);
 363 }
 364
 365 static struct serio_device_id serio_raw_serio_ids[] = {
 366         {
 367                 .type   = SERIO_8042,
 368                 .proto  = SERIO_ANY,
 369                 .id     = SERIO_ANY,
 370                 .extra  = SERIO_ANY,
 371         },
 372         { 0 }
 373 };
 374
 375 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
 376
 377 static struct serio_driver serio_raw_drv = {
 378         .driver         = {
 379                 .name   = "serio_raw",
 380         },
 381         .description    = DRIVER_DESC,
 382         .id_table       = serio_raw_serio_ids,
 383         .interrupt      = serio_raw_interrupt,
 384         .connect        = serio_raw_connect,
 385         .reconnect      = serio_raw_reconnect,
 386         .disconnect     = serio_raw_disconnect,
 387         .manual_bind    = 1,
 388 };
 389
 390 static int __init serio_raw_init(void)
 391 {
 392         return serio_register_driver(&serio_raw_drv);
 393 }
 394
 395 static void __exit serio_raw_exit(void)
 396 {
 397         serio_unregister_driver(&serio_raw_drv);
 398 }
 399
 400 module_init(serio_raw_init);
 401 module_exit(serio_raw_exit);