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/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/smp_lock.h>
  15 #include <linux/poll.h>
  16 #include <linux/module.h>
  17 #include <linux/serio.h>
  18 #include <linux/init.h>
  19 #include <linux/major.h>
  20 #include <linux/device.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/wait.h>
  23 #include <linux/mutex.h>
  24
  25 #define DRIVER_DESC     "Raw serio driver"
  26
  27 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
  28 MODULE_DESCRIPTION(DRIVER_DESC);
  29 MODULE_LICENSE("GPL");
  30
  31 #define SERIO_RAW_QUEUE_LEN     64
  32 struct serio_raw {
  33         unsigned char queue[SERIO_RAW_QUEUE_LEN];
  34         unsigned int tail, head;
  35
  36         char name[16];
  37         unsigned int refcnt;
  38         struct serio *serio;
  39         struct miscdevice dev;
  40         wait_queue_head_t wait;
  41         struct list_head list;
  42         struct list_head node;
  43 };
  44
  45 struct serio_raw_list {
  46         struct fasync_struct *fasync;
  47         struct serio_raw *serio_raw;
  48         struct list_head node;
  49 };
  50
  51 static DEFINE_MUTEX(serio_raw_mutex);
  52 static LIST_HEAD(serio_raw_list);
  53 static unsigned int serio_raw_no;
  54
  55 /*********************************************************************
  56  *             Interface with userspace (file operations)            *
  57  *********************************************************************/
  58
  59 static int serio_raw_fasync(int fd, struct file *file, int on)
  60 {
  61         struct serio_raw_list *list = file->private_data;
  62
  63         return fasync_helper(fd, file, on, &list->fasync);
  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         lock_kernel();
  85         retval = mutex_lock_interruptible(&serio_raw_mutex);
  86         if (retval)
  87                 goto out_bkl;
  88
  89         if (!(serio_raw = serio_raw_locate(iminor(inode)))) {
  90                 retval = -ENODEV;
  91                 goto out;
  92         }
  93
  94         if (!serio_raw->serio) {
  95                 retval = -ENODEV;
  96                 goto out;
  97         }
  98
  99         if (!(list = kzalloc(sizeof(struct serio_raw_list), GFP_KERNEL))) {
 100                 retval = -ENOMEM;
 101                 goto out;
 102         }
 103
 104         list->serio_raw = serio_raw;
 105         file->private_data = list;
 106
 107         serio_raw->refcnt++;
 108         list_add_tail(&list->node, &serio_raw->list);
 109
 110 out:
 111         mutex_unlock(&serio_raw_mutex);
 112 out_bkl:
 113         unlock_kernel();
 114         return retval;
 115 }
 116
 117 static int serio_raw_cleanup(struct serio_raw *serio_raw)
 118 {
 119         if (--serio_raw->refcnt == 0) {
 120                 misc_deregister(&serio_raw->dev);
 121                 list_del_init(&serio_raw->node);
 122                 kfree(serio_raw);
 123
 124                 return 1;
 125         }
 126
 127         return 0;
 128 }
 129
 130 static int serio_raw_release(struct inode *inode, struct file *file)
 131 {
 132         struct serio_raw_list *list = file->private_data;
 133         struct serio_raw *serio_raw = list->serio_raw;
 134
 135         mutex_lock(&serio_raw_mutex);
 136
 137         serio_raw_cleanup(serio_raw);
 138
 139         mutex_unlock(&serio_raw_mutex);
 140         return 0;
 141 }
 142
 143 static int serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
 144 {
 145         unsigned long flags;
 146         int empty;
 147
 148         spin_lock_irqsave(&serio_raw->serio->lock, flags);
 149
 150         empty = serio_raw->head == serio_raw->tail;
 151         if (!empty) {
 152                 *c = serio_raw->queue[serio_raw->tail];
 153                 serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
 154         }
 155
 156         spin_unlock_irqrestore(&serio_raw->serio->lock, flags);
 157
 158         return !empty;
 159 }
 160
 161 static ssize_t serio_raw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 162 {
 163         struct serio_raw_list *list = file->private_data;
 164         struct serio_raw *serio_raw = list->serio_raw;
 165         char uninitialized_var(c);
 166         ssize_t retval = 0;
 167
 168         if (!serio_raw->serio)
 169                 return -ENODEV;
 170
 171         if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
 172                 return -EAGAIN;
 173
 174         retval = wait_event_interruptible(list->serio_raw->wait,
 175                                           serio_raw->head != serio_raw->tail || !serio_raw->serio);
 176         if (retval)
 177                 return retval;
 178
 179         if (!serio_raw->serio)
 180                 return -ENODEV;
 181
 182         while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
 183                 if (put_user(c, buffer++))
 184                         return -EFAULT;
 185                 retval++;
 186         }
 187
 188         return retval;
 189 }
 190
 191 static ssize_t serio_raw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 192 {
 193         struct serio_raw_list *list = file->private_data;
 194         ssize_t written = 0;
 195         int retval;
 196         unsigned char c;
 197
 198         retval = mutex_lock_interruptible(&serio_raw_mutex);
 199         if (retval)
 200                 return retval;
 201
 202         if (!list->serio_raw->serio) {
 203                 retval = -ENODEV;
 204                 goto out;
 205         }
 206
 207         if (count > 32)
 208                 count = 32;
 209
 210         while (count--) {
 211                 if (get_user(c, buffer++)) {
 212                         retval = -EFAULT;
 213                         goto out;
 214                 }
 215                 if (serio_write(list->serio_raw->serio, c)) {
 216                         retval = -EIO;
 217                         goto out;
 218                 }
 219                 written++;
 220         };
 221
 222 out:
 223         mutex_unlock(&serio_raw_mutex);
 224         return written;
 225 }
 226
 227 static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
 228 {
 229         struct serio_raw_list *list = file->private_data;
 230
 231         poll_wait(file, &list->serio_raw->wait, wait);
 232
 233         if (list->serio_raw->head != list->serio_raw->tail)
 234                 return POLLIN | POLLRDNORM;
 235
 236         return 0;
 237 }
 238
 239 static const struct file_operations serio_raw_fops = {
 240         .owner =        THIS_MODULE,
 241         .open =         serio_raw_open,
 242         .release =      serio_raw_release,
 243         .read =         serio_raw_read,
 244         .write =        serio_raw_write,
 245         .poll =         serio_raw_poll,
 246         .fasync =       serio_raw_fasync,
 247 };
 248
 249
 250 /*********************************************************************
 251  *                   Interface with serio port                       *
 252  *********************************************************************/
 253
 254 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
 255                                         unsigned int dfl)
 256 {
 257         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 258         struct serio_raw_list *list;
 259         unsigned int head = serio_raw->head;
 260
 261         /* we are holding serio->lock here so we are prootected */
 262         serio_raw->queue[head] = data;
 263         head = (head + 1) % SERIO_RAW_QUEUE_LEN;
 264         if (likely(head != serio_raw->tail)) {
 265                 serio_raw->head = head;
 266                 list_for_each_entry(list, &serio_raw->list, node)
 267                         kill_fasync(&list->fasync, SIGIO, POLL_IN);
 268                 wake_up_interruptible(&serio_raw->wait);
 269         }
 270
 271         return IRQ_HANDLED;
 272 }
 273
 274 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
 275 {
 276         struct serio_raw *serio_raw;
 277         int err;
 278
 279         if (!(serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL))) {
 280                 printk(KERN_ERR "serio_raw.c: can't allocate memory for a device\n");
 281                 return -ENOMEM;
 282         }
 283
 284         mutex_lock(&serio_raw_mutex);
 285
 286         snprintf(serio_raw->name, sizeof(serio_raw->name), "serio_raw%d", serio_raw_no++);
 287         serio_raw->refcnt = 1;
 288         serio_raw->serio = serio;
 289         INIT_LIST_HEAD(&serio_raw->list);
 290         init_waitqueue_head(&serio_raw->wait);
 291
 292         serio_set_drvdata(serio, serio_raw);
 293
 294         err = serio_open(serio, drv);
 295         if (err)
 296                 goto out_free;
 297
 298         list_add_tail(&serio_raw->node, &serio_raw_list);
 299
 300         serio_raw->dev.minor = PSMOUSE_MINOR;
 301         serio_raw->dev.name = serio_raw->name;
 302         serio_raw->dev.parent = &serio->dev;
 303         serio_raw->dev.fops = &serio_raw_fops;
 304
 305         err = misc_register(&serio_raw->dev);
 306         if (err) {
 307                 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
 308                 err = misc_register(&serio_raw->dev);
 309         }
 310
 311         if (err) {
 312                 printk(KERN_INFO "serio_raw: failed to register raw access device for %s\n",
 313                         serio->phys);
 314                 goto out_close;
 315         }
 316
 317         printk(KERN_INFO "serio_raw: raw access enabled on %s (%s, minor %d)\n",
 318                 serio->phys, serio_raw->name, serio_raw->dev.minor);
 319         goto out;
 320
 321 out_close:
 322         serio_close(serio);
 323         list_del_init(&serio_raw->node);
 324 out_free:
 325         serio_set_drvdata(serio, NULL);
 326         kfree(serio_raw);
 327 out:
 328         mutex_unlock(&serio_raw_mutex);
 329         return err;
 330 }
 331
 332 static int serio_raw_reconnect(struct serio *serio)
 333 {
 334         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 335         struct serio_driver *drv = serio->drv;
 336
 337         if (!drv || !serio_raw) {
 338                 printk(KERN_DEBUG "serio_raw: reconnect request, but serio is disconnected, ignoring...\n");
 339                 return -1;
 340         }
 341
 342         /*
 343          * Nothing needs to be done here, we just need this method to
 344          * keep the same device.
 345          */
 346         return 0;
 347 }
 348
 349 static void serio_raw_disconnect(struct serio *serio)
 350 {
 351         struct serio_raw *serio_raw;
 352
 353         mutex_lock(&serio_raw_mutex);
 354
 355         serio_raw = serio_get_drvdata(serio);
 356
 357         serio_close(serio);
 358         serio_set_drvdata(serio, NULL);
 359
 360         serio_raw->serio = NULL;
 361         if (!serio_raw_cleanup(serio_raw))
 362                 wake_up_interruptible(&serio_raw->wait);
 363
 364         mutex_unlock(&serio_raw_mutex);
 365 }
 366
 367 static struct serio_device_id serio_raw_serio_ids[] = {
 368         {
 369                 .type   = SERIO_8042,
 370                 .proto  = SERIO_ANY,
 371                 .id     = SERIO_ANY,
 372                 .extra  = SERIO_ANY,
 373         },
 374         {
 375                 .type   = SERIO_8042_XL,
 376                 .proto  = SERIO_ANY,
 377                 .id     = SERIO_ANY,
 378                 .extra  = SERIO_ANY,
 379         },
 380         { 0 }
 381 };
 382
 383 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
 384
 385 static struct serio_driver serio_raw_drv = {
 386         .driver         = {
 387                 .name   = "serio_raw",
 388         },
 389         .description    = DRIVER_DESC,
 390         .id_table       = serio_raw_serio_ids,
 391         .interrupt      = serio_raw_interrupt,
 392         .connect        = serio_raw_connect,
 393         .reconnect      = serio_raw_reconnect,
 394         .disconnect     = serio_raw_disconnect,
 395         .manual_bind    = 1,
 396 };
 397
 398 static int __init serio_raw_init(void)
 399 {
 400         return serio_register_driver(&serio_raw_drv);
 401 }
 402
 403 static void __exit serio_raw_exit(void)
 404 {
 405         serio_unregister_driver(&serio_raw_drv);
 406 }
 407
 408 module_init(serio_raw_init);
 409 module_exit(serio_raw_exit);