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/smp_lock.h>
  14 #include <linux/poll.h>
  15 #include <linux/module.h>
  16 #include <linux/serio.h>
  17 #include <linux/init.h>
  18 #include <linux/major.h>
  19 #include <linux/device.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/wait.h>
  22 #include <linux/mutex.h>
  23
  24 #define DRIVER_DESC     "Raw serio driver"
  25
  26 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
  27 MODULE_DESCRIPTION(DRIVER_DESC);
  28 MODULE_LICENSE("GPL");
  29
  30 #define SERIO_RAW_QUEUE_LEN     64
  31 struct serio_raw {
  32         unsigned char queue[SERIO_RAW_QUEUE_LEN];
  33         unsigned int tail, head;
  34
  35         char name[16];
  36         unsigned int refcnt;
  37         struct serio *serio;
  38         struct miscdevice dev;
  39         wait_queue_head_t wait;
  40         struct list_head list;
  41         struct list_head node;
  42 };
  43
  44 struct serio_raw_list {
  45         struct fasync_struct *fasync;
  46         struct serio_raw *serio_raw;
  47         struct list_head node;
  48 };
  49
  50 static DEFINE_MUTEX(serio_raw_mutex);
  51 static LIST_HEAD(serio_raw_list);
  52 static unsigned int serio_raw_no;
  53
  54 /*********************************************************************
  55  *             Interface with userspace (file operations)            *
  56  *********************************************************************/
  57
  58 static int serio_raw_fasync(int fd, struct file *file, int on)
  59 {
  60         struct serio_raw_list *list = file->private_data;
  61         int retval;
  62
  63         retval = fasync_helper(fd, file, on, &list->fasync);
  64         return retval < 0 ? retval : 0;
  65 }
  66
  67 static struct serio_raw *serio_raw_locate(int minor)
  68 {
  69         struct serio_raw *serio_raw;
  70
  71         list_for_each_entry(serio_raw, &serio_raw_list, node) {
  72                 if (serio_raw->dev.minor == minor)
  73                         return serio_raw;
  74         }
  75
  76         return NULL;
  77 }
  78
  79 static int serio_raw_open(struct inode *inode, struct file *file)
  80 {
  81         struct serio_raw *serio_raw;
  82         struct serio_raw_list *list;
  83         int retval = 0;
  84
  85         lock_kernel();
  86         retval = mutex_lock_interruptible(&serio_raw_mutex);
  87         if (retval)
  88                 goto out_bkl;
  89
  90         if (!(serio_raw = serio_raw_locate(iminor(inode)))) {
  91                 retval = -ENODEV;
  92                 goto out;
  93         }
  94
  95         if (!serio_raw->serio) {
  96                 retval = -ENODEV;
  97                 goto out;
  98         }
  99
 100         if (!(list = kzalloc(sizeof(struct serio_raw_list), GFP_KERNEL))) {
 101                 retval = -ENOMEM;
 102                 goto out;
 103         }
 104
 105         list->serio_raw = serio_raw;
 106         file->private_data = list;
 107
 108         serio_raw->refcnt++;
 109         list_add_tail(&list->node, &serio_raw->list);
 110
 111 out:
 112         mutex_unlock(&serio_raw_mutex);
 113 out_bkl:
 114         unlock_kernel();
 115         return retval;
 116 }
 117
 118 static int serio_raw_cleanup(struct serio_raw *serio_raw)
 119 {
 120         if (--serio_raw->refcnt == 0) {
 121                 misc_deregister(&serio_raw->dev);
 122                 list_del_init(&serio_raw->node);
 123                 kfree(serio_raw);
 124
 125                 return 1;
 126         }
 127
 128         return 0;
 129 }
 130
 131 static int serio_raw_release(struct inode *inode, struct file *file)
 132 {
 133         struct serio_raw_list *list = file->private_data;
 134         struct serio_raw *serio_raw = list->serio_raw;
 135
 136         mutex_lock(&serio_raw_mutex);
 137
 138         serio_raw_fasync(-1, file, 0);
 139         serio_raw_cleanup(serio_raw);
 140
 141         mutex_unlock(&serio_raw_mutex);
 142         return 0;
 143 }
 144
 145 static int serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
 146 {
 147         unsigned long flags;
 148         int empty;
 149
 150         spin_lock_irqsave(&serio_raw->serio->lock, flags);
 151
 152         empty = serio_raw->head == serio_raw->tail;
 153         if (!empty) {
 154                 *c = serio_raw->queue[serio_raw->tail];
 155                 serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
 156         }
 157
 158         spin_unlock_irqrestore(&serio_raw->serio->lock, flags);
 159
 160         return !empty;
 161 }
 162
 163 static ssize_t serio_raw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 164 {
 165         struct serio_raw_list *list = file->private_data;
 166         struct serio_raw *serio_raw = list->serio_raw;
 167         char uninitialized_var(c);
 168         ssize_t retval = 0;
 169
 170         if (!serio_raw->serio)
 171                 return -ENODEV;
 172
 173         if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
 174                 return -EAGAIN;
 175
 176         retval = wait_event_interruptible(list->serio_raw->wait,
 177                                           serio_raw->head != serio_raw->tail || !serio_raw->serio);
 178         if (retval)
 179                 return retval;
 180
 181         if (!serio_raw->serio)
 182                 return -ENODEV;
 183
 184         while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
 185                 if (put_user(c, buffer++))
 186                         return -EFAULT;
 187                 retval++;
 188         }
 189
 190         return retval;
 191 }
 192
 193 static ssize_t serio_raw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 194 {
 195         struct serio_raw_list *list = file->private_data;
 196         ssize_t written = 0;
 197         int retval;
 198         unsigned char c;
 199
 200         retval = mutex_lock_interruptible(&serio_raw_mutex);
 201         if (retval)
 202                 return retval;
 203
 204         if (!list->serio_raw->serio) {
 205                 retval = -ENODEV;
 206                 goto out;
 207         }
 208
 209         if (count > 32)
 210                 count = 32;
 211
 212         while (count--) {
 213                 if (get_user(c, buffer++)) {
 214                         retval = -EFAULT;
 215                         goto out;
 216                 }
 217                 if (serio_write(list->serio_raw->serio, c)) {
 218                         retval = -EIO;
 219                         goto out;
 220                 }
 221                 written++;
 222         };
 223
 224 out:
 225         mutex_unlock(&serio_raw_mutex);
 226         return written;
 227 }
 228
 229 static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
 230 {
 231         struct serio_raw_list *list = file->private_data;
 232
 233         poll_wait(file, &list->serio_raw->wait, wait);
 234
 235         if (list->serio_raw->head != list->serio_raw->tail)
 236                 return POLLIN | POLLRDNORM;
 237
 238         return 0;
 239 }
 240
 241 static const struct file_operations serio_raw_fops = {
 242         .owner =        THIS_MODULE,
 243         .open =         serio_raw_open,
 244         .release =      serio_raw_release,
 245         .read =         serio_raw_read,
 246         .write =        serio_raw_write,
 247         .poll =         serio_raw_poll,
 248         .fasync =       serio_raw_fasync,
 249 };
 250
 251
 252 /*********************************************************************
 253  *                   Interface with serio port                       *
 254  *********************************************************************/
 255
 256 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
 257                                         unsigned int dfl)
 258 {
 259         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 260         struct serio_raw_list *list;
 261         unsigned int head = serio_raw->head;
 262
 263         /* we are holding serio->lock here so we are prootected */
 264         serio_raw->queue[head] = data;
 265         head = (head + 1) % SERIO_RAW_QUEUE_LEN;
 266         if (likely(head != serio_raw->tail)) {
 267                 serio_raw->head = head;
 268                 list_for_each_entry(list, &serio_raw->list, node)
 269                         kill_fasync(&list->fasync, SIGIO, POLL_IN);
 270                 wake_up_interruptible(&serio_raw->wait);
 271         }
 272
 273         return IRQ_HANDLED;
 274 }
 275
 276 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
 277 {
 278         struct serio_raw *serio_raw;
 279         int err;
 280
 281         if (!(serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL))) {
 282                 printk(KERN_ERR "serio_raw.c: can't allocate memory for a device\n");
 283                 return -ENOMEM;
 284         }
 285
 286         mutex_lock(&serio_raw_mutex);
 287
 288         snprintf(serio_raw->name, sizeof(serio_raw->name), "serio_raw%d", serio_raw_no++);
 289         serio_raw->refcnt = 1;
 290         serio_raw->serio = serio;
 291         INIT_LIST_HEAD(&serio_raw->list);
 292         init_waitqueue_head(&serio_raw->wait);
 293
 294         serio_set_drvdata(serio, serio_raw);
 295
 296         err = serio_open(serio, drv);
 297         if (err)
 298                 goto out_free;
 299
 300         list_add_tail(&serio_raw->node, &serio_raw_list);
 301
 302         serio_raw->dev.minor = PSMOUSE_MINOR;
 303         serio_raw->dev.name = serio_raw->name;
 304         serio_raw->dev.parent = &serio->dev;
 305         serio_raw->dev.fops = &serio_raw_fops;
 306
 307         err = misc_register(&serio_raw->dev);
 308         if (err) {
 309                 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
 310                 err = misc_register(&serio_raw->dev);
 311         }
 312
 313         if (err) {
 314                 printk(KERN_INFO "serio_raw: failed to register raw access device for %s\n",
 315                         serio->phys);
 316                 goto out_close;
 317         }
 318
 319         printk(KERN_INFO "serio_raw: raw access enabled on %s (%s, minor %d)\n",
 320                 serio->phys, serio_raw->name, serio_raw->dev.minor);
 321         goto out;
 322
 323 out_close:
 324         serio_close(serio);
 325         list_del_init(&serio_raw->node);
 326 out_free:
 327         serio_set_drvdata(serio, NULL);
 328         kfree(serio_raw);
 329 out:
 330         mutex_unlock(&serio_raw_mutex);
 331         return err;
 332 }
 333
 334 static int serio_raw_reconnect(struct serio *serio)
 335 {
 336         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 337         struct serio_driver *drv = serio->drv;
 338
 339         if (!drv || !serio_raw) {
 340                 printk(KERN_DEBUG "serio_raw: reconnect request, but serio is disconnected, ignoring...\n");
 341                 return -1;
 342         }
 343
 344         /*
 345          * Nothing needs to be done here, we just need this method to
 346          * keep the same device.
 347          */
 348         return 0;
 349 }
 350
 351 static void serio_raw_disconnect(struct serio *serio)
 352 {
 353         struct serio_raw *serio_raw;
 354
 355         mutex_lock(&serio_raw_mutex);
 356
 357         serio_raw = serio_get_drvdata(serio);
 358
 359         serio_close(serio);
 360         serio_set_drvdata(serio, NULL);
 361
 362         serio_raw->serio = NULL;
 363         if (!serio_raw_cleanup(serio_raw))
 364                 wake_up_interruptible(&serio_raw->wait);
 365
 366         mutex_unlock(&serio_raw_mutex);
 367 }
 368
 369 static struct serio_device_id serio_raw_serio_ids[] = {
 370         {
 371                 .type   = SERIO_8042,
 372                 .proto  = SERIO_ANY,
 373                 .id     = SERIO_ANY,
 374                 .extra  = SERIO_ANY,
 375         },
 376         { 0 }
 377 };
 378
 379 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
 380
 381 static struct serio_driver serio_raw_drv = {
 382         .driver         = {
 383                 .name   = "serio_raw",
 384         },
 385         .description    = DRIVER_DESC,
 386         .id_table       = serio_raw_serio_ids,
 387         .interrupt      = serio_raw_interrupt,
 388         .connect        = serio_raw_connect,
 389         .reconnect      = serio_raw_reconnect,
 390         .disconnect     = serio_raw_disconnect,
 391         .manual_bind    = 1,
 392 };
 393
 394 static int __init serio_raw_init(void)
 395 {
 396         return serio_register_driver(&serio_raw_drv);
 397 }
 398
 399 static void __exit serio_raw_exit(void)
 400 {
 401         serio_unregister_driver(&serio_raw_drv);
 402 }
 403
 404 module_init(serio_raw_init);
 405 module_exit(serio_raw_exit);