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/devfs_fs_kernel.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/wait.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 DECLARE_MUTEX(serio_raw_sem);
  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 = down_interruptible(&serio_raw_sem);
  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 = kmalloc(sizeof(struct serio_raw_list), GFP_KERNEL))) {
  99                 retval = -ENOMEM;
 100                 goto out;
 101         }
 102
 103         memset(list, 0, sizeof(struct serio_raw_list));
 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         up(&serio_raw_sem);
 112         return retval;
 113 }
 114
 115 static int serio_raw_cleanup(struct serio_raw *serio_raw)
 116 {
 117         if (--serio_raw->refcnt == 0) {
 118                 misc_deregister(&serio_raw->dev);
 119                 list_del_init(&serio_raw->node);
 120                 kfree(serio_raw);
 121
 122                 return 1;
 123         }
 124
 125         return 0;
 126 }
 127
 128 static int serio_raw_release(struct inode *inode, struct file *file)
 129 {
 130         struct serio_raw_list *list = file->private_data;
 131         struct serio_raw *serio_raw = list->serio_raw;
 132
 133         down(&serio_raw_sem);
 134
 135         serio_raw_fasync(-1, file, 0);
 136         serio_raw_cleanup(serio_raw);
 137
 138         up(&serio_raw_sem);
 139         return 0;
 140 }
 141
 142 static int serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
 143 {
 144         unsigned long flags;
 145         int empty;
 146
 147         spin_lock_irqsave(&serio_raw->serio->lock, flags);
 148
 149         empty = serio_raw->head == serio_raw->tail;
 150         if (!empty) {
 151                 *c = serio_raw->queue[serio_raw->tail];
 152                 serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
 153         }
 154
 155         spin_unlock_irqrestore(&serio_raw->serio->lock, flags);
 156
 157         return !empty;
 158 }
 159
 160 static ssize_t serio_raw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 161 {
 162         struct serio_raw_list *list = file->private_data;
 163         struct serio_raw *serio_raw = list->serio_raw;
 164         char c;
 165         ssize_t retval = 0;
 166
 167         if (!serio_raw->serio)
 168                 return -ENODEV;
 169
 170         if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
 171                 return -EAGAIN;
 172
 173         retval = wait_event_interruptible(list->serio_raw->wait,
 174                                           serio_raw->head != serio_raw->tail || !serio_raw->serio);
 175         if (retval)
 176                 return retval;
 177
 178         if (!serio_raw->serio)
 179                 return -ENODEV;
 180
 181         while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
 182                 if (put_user(c, buffer++))
 183                         return -EFAULT;
 184                 retval++;
 185         }
 186
 187         return retval;
 188 }
 189
 190 static ssize_t serio_raw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 191 {
 192         struct serio_raw_list *list = file->private_data;
 193         ssize_t written = 0;
 194         int retval;
 195         unsigned char c;
 196
 197         retval = down_interruptible(&serio_raw_sem);
 198         if (retval)
 199                 return retval;
 200
 201         if (!list->serio_raw->serio) {
 202                 retval = -ENODEV;
 203                 goto out;
 204         }
 205
 206         if (count > 32)
 207                 count = 32;
 208
 209         while (count--) {
 210                 if (get_user(c, buffer++)) {
 211                         retval = -EFAULT;
 212                         goto out;
 213                 }
 214                 if (serio_write(list->serio_raw->serio, c)) {
 215                         retval = -EIO;
 216                         goto out;
 217                 }
 218                 written++;
 219         };
 220
 221 out:
 222         up(&serio_raw_sem);
 223         return written;
 224 }
 225
 226 static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
 227 {
 228         struct serio_raw_list *list = file->private_data;
 229
 230         poll_wait(file, &list->serio_raw->wait, wait);
 231
 232         if (list->serio_raw->head != list->serio_raw->tail)
 233                 return POLLIN | POLLRDNORM;
 234
 235         return 0;
 236 }
 237
 238 static struct file_operations serio_raw_fops = {
 239         .owner =        THIS_MODULE,
 240         .open =         serio_raw_open,
 241         .release =      serio_raw_release,
 242         .read =         serio_raw_read,
 243         .write =        serio_raw_write,
 244         .poll =         serio_raw_poll,
 245         .fasync =       serio_raw_fasync,
 246 };
 247
 248
 249 /*********************************************************************
 250  *                   Interface with serio port                       *
 251  *********************************************************************/
 252
 253 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
 254                                         unsigned int dfl, struct pt_regs *regs)
 255 {
 256         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 257         struct serio_raw_list *list;
 258         unsigned int head = serio_raw->head;
 259
 260         /* we are holding serio->lock here so we are prootected */
 261         serio_raw->queue[head] = data;
 262         head = (head + 1) % SERIO_RAW_QUEUE_LEN;
 263         if (likely(head != serio_raw->tail)) {
 264                 serio_raw->head = head;
 265                 list_for_each_entry(list, &serio_raw->list, node)
 266                         kill_fasync(&list->fasync, SIGIO, POLL_IN);
 267                 wake_up_interruptible(&serio_raw->wait);
 268         }
 269
 270         return IRQ_HANDLED;
 271 }
 272
 273 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
 274 {
 275         struct serio_raw *serio_raw;
 276         int err;
 277
 278         if (!(serio_raw = kmalloc(sizeof(struct serio_raw), GFP_KERNEL))) {
 279                 printk(KERN_ERR "serio_raw.c: can't allocate memory for a device\n");
 280                 return -ENOMEM;
 281         }
 282
 283         down(&serio_raw_sem);
 284
 285         memset(serio_raw, 0, sizeof(struct serio_raw));
 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.fops = &serio_raw_fops;
 303
 304         err = misc_register(&serio_raw->dev);
 305         if (err) {
 306                 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
 307                 err = misc_register(&serio_raw->dev);
 308         }
 309
 310         if (err) {
 311                 printk(KERN_INFO "serio_raw: failed to register raw access device for %s\n",
 312                         serio->phys);
 313                 goto out_close;
 314         }
 315
 316         printk(KERN_INFO "serio_raw: raw access enabled on %s (%s, minor %d)\n",
 317                 serio->phys, serio_raw->name, serio_raw->dev.minor);
 318         goto out;
 319
 320 out_close:
 321         serio_close(serio);
 322         list_del_init(&serio_raw->node);
 323 out_free:
 324         serio_set_drvdata(serio, NULL);
 325         kfree(serio_raw);
 326 out:
 327         up(&serio_raw_sem);
 328         return err;
 329 }
 330
 331 static int serio_raw_reconnect(struct serio *serio)
 332 {
 333         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 334         struct serio_driver *drv = serio->drv;
 335
 336         if (!drv || !serio_raw) {
 337                 printk(KERN_DEBUG "serio_raw: reconnect request, but serio is disconnected, ignoring...\n");
 338                 return -1;
 339         }
 340
 341         /*
 342          * Nothing needs to be done here, we just need this method to
 343          * keep the same device.
 344          */
 345         return 0;
 346 }
 347
 348 static void serio_raw_disconnect(struct serio *serio)
 349 {
 350         struct serio_raw *serio_raw;
 351
 352         down(&serio_raw_sem);
 353
 354         serio_raw = serio_get_drvdata(serio);
 355
 356         serio_close(serio);
 357         serio_set_drvdata(serio, NULL);
 358
 359         serio_raw->serio = NULL;
 360         if (!serio_raw_cleanup(serio_raw))
 361                 wake_up_interruptible(&serio_raw->wait);
 362
 363         up(&serio_raw_sem);
 364 }
 365
 366 static struct serio_device_id serio_raw_serio_ids[] = {
 367         {
 368                 .type   = SERIO_8042,
 369                 .proto  = SERIO_ANY,
 370                 .id     = SERIO_ANY,
 371                 .extra  = SERIO_ANY,
 372         },
 373         { 0 }
 374 };
 375
 376 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
 377
 378 static struct serio_driver serio_raw_drv = {
 379         .driver         = {
 380                 .name   = "serio_raw",
 381         },
 382         .description    = DRIVER_DESC,
 383         .id_table       = serio_raw_serio_ids,
 384         .interrupt      = serio_raw_interrupt,
 385         .connect        = serio_raw_connect,
 386         .reconnect      = serio_raw_reconnect,
 387         .disconnect     = serio_raw_disconnect,
 388         .manual_bind    = 1,
 389 };
 390
 391 static int __init serio_raw_init(void)
 392 {
 393         serio_register_driver(&serio_raw_drv);
 394         return 0;
 395 }
 396
 397 static void __exit serio_raw_exit(void)
 398 {
 399         serio_unregister_driver(&serio_raw_drv);
 400 }
 401
 402 module_init(serio_raw_init);
 403 module_exit(serio_raw_exit);