drivers/input/serio/serio_raw.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Raw serio device providing access to a raw byte stream from underlying
   4  * serio port. Closely emulates behavior of pre-2.6 /dev/psaux device
   5  *
   6  * Copyright (c) 2004 Dmitry Torokhov
   7  */
   8
   9 #include <linux/kref.h>
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/poll.h>
  13 #include <linux/module.h>
  14 #include <linux/serio.h>
  15 #include <linux/major.h>
  16 #include <linux/device.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/wait.h>
  19 #include <linux/mutex.h>
  20
  21 #define DRIVER_DESC     "Raw serio driver"
  22
  23 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
  24 MODULE_DESCRIPTION(DRIVER_DESC);
  25 MODULE_LICENSE("GPL");
  26
  27 #define SERIO_RAW_QUEUE_LEN     64
  28 struct serio_raw {
  29         unsigned char queue[SERIO_RAW_QUEUE_LEN];
  30         unsigned int tail, head;
  31
  32         char name[20];
  33         struct kref kref;
  34         struct serio *serio;
  35         struct miscdevice dev;
  36         wait_queue_head_t wait;
  37         struct list_head client_list;
  38         struct list_head node;
  39         bool dead;
  40 };
  41
  42 struct serio_raw_client {
  43         struct fasync_struct *fasync;
  44         struct serio_raw *serio_raw;
  45         struct list_head node;
  46 };
  47
  48 static DEFINE_MUTEX(serio_raw_mutex);
  49 static LIST_HEAD(serio_raw_list);
  50
  51 /*********************************************************************
  52  *             Interface with userspace (file operations)            *
  53  *********************************************************************/
  54
  55 static int serio_raw_fasync(int fd, struct file *file, int on)
  56 {
  57         struct serio_raw_client *client = file->private_data;
  58
  59         return fasync_helper(fd, file, on, &client->fasync);
  60 }
  61
  62 static struct serio_raw *serio_raw_locate(int minor)
  63 {
  64         struct serio_raw *serio_raw;
  65
  66         list_for_each_entry(serio_raw, &serio_raw_list, node) {
  67                 if (serio_raw->dev.minor == minor)
  68                         return serio_raw;
  69         }
  70
  71         return NULL;
  72 }
  73
  74 static int serio_raw_open(struct inode *inode, struct file *file)
  75 {
  76         struct serio_raw *serio_raw;
  77         struct serio_raw_client *client;
  78
  79         scoped_guard(mutex_intr, &serio_raw_mutex) {
  80                 serio_raw = serio_raw_locate(iminor(inode));
  81                 if (!serio_raw)
  82                         return -ENODEV;
  83
  84                 if (serio_raw->dead)
  85                         return -ENODEV;
  86
  87                 client = kzalloc(sizeof(*client), GFP_KERNEL);
  88                 if (!client)
  89                         return -ENOMEM;
  90
  91                 client->serio_raw = serio_raw;
  92                 file->private_data = client;
  93
  94                 kref_get(&serio_raw->kref);
  95
  96                 scoped_guard(serio_pause_rx, serio_raw->serio)
  97                         list_add_tail(&client->node, &serio_raw->client_list);
  98
  99                 return 0;
 100         }
 101
 102         return -EINTR;
 103 }
 104
 105 static void serio_raw_free(struct kref *kref)
 106 {
 107         struct serio_raw *serio_raw =
 108                         container_of(kref, struct serio_raw, kref);
 109
 110         put_device(&serio_raw->serio->dev);
 111         kfree(serio_raw);
 112 }
 113
 114 static int serio_raw_release(struct inode *inode, struct file *file)
 115 {
 116         struct serio_raw_client *client = file->private_data;
 117         struct serio_raw *serio_raw = client->serio_raw;
 118
 119         scoped_guard(serio_pause_rx, serio_raw->serio)
 120                 list_del(&client->node);
 121
 122         kfree(client);
 123
 124         kref_put(&serio_raw->kref, serio_raw_free);
 125
 126         return 0;
 127 }
 128
 129 static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
 130 {
 131         guard(serio_pause_rx)(serio_raw->serio);
 132
 133         if (serio_raw->head == serio_raw->tail)
 134                 return false; /* queue is empty */
 135
 136         *c = serio_raw->queue[serio_raw->tail];
 137         serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
 138
 139         return true;
 140 }
 141
 142 static ssize_t serio_raw_read(struct file *file, char __user *buffer,
 143                               size_t count, loff_t *ppos)
 144 {
 145         struct serio_raw_client *client = file->private_data;
 146         struct serio_raw *serio_raw = client->serio_raw;
 147         char c;
 148         ssize_t read = 0;
 149         int error;
 150
 151         for (;;) {
 152                 if (serio_raw->dead)
 153                         return -ENODEV;
 154
 155                 if (serio_raw->head == serio_raw->tail &&
 156                     (file->f_flags & O_NONBLOCK))
 157                         return -EAGAIN;
 158
 159                 if (count == 0)
 160                         break;
 161
 162                 while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
 163                         if (put_user(c, buffer++))
 164                                 return -EFAULT;
 165                         read++;
 166                 }
 167
 168                 if (read)
 169                         break;
 170
 171                 if (!(file->f_flags & O_NONBLOCK)) {
 172                         error = wait_event_interruptible(serio_raw->wait,
 173                                         serio_raw->head != serio_raw->tail ||
 174                                         serio_raw->dead);
 175                         if (error)
 176                                 return error;
 177                 }
 178         }
 179
 180         return read;
 181 }
 182
 183 static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
 184                                size_t count, loff_t *ppos)
 185 {
 186         struct serio_raw_client *client = file->private_data;
 187         struct serio_raw *serio_raw = client->serio_raw;
 188         int written = 0;
 189         unsigned char c;
 190
 191         scoped_guard(mutex_intr, &serio_raw_mutex) {
 192                 if (serio_raw->dead)
 193                         return -ENODEV;
 194
 195                 if (count > 32)
 196                         count = 32;
 197
 198                 while (count--) {
 199                         if (get_user(c, buffer++))
 200                                 return -EFAULT;
 201
 202                         if (serio_write(serio_raw->serio, c)) {
 203                                 /* Either signal error or partial write */
 204                                 return written ?: -EIO;
 205                         }
 206
 207                         written++;
 208                 }
 209
 210                 return written;
 211         }
 212
 213         return -EINTR;
 214 }
 215
 216 static __poll_t serio_raw_poll(struct file *file, poll_table *wait)
 217 {
 218         struct serio_raw_client *client = file->private_data;
 219         struct serio_raw *serio_raw = client->serio_raw;
 220         __poll_t mask;
 221
 222         poll_wait(file, &serio_raw->wait, wait);
 223
 224         mask = serio_raw->dead ? EPOLLHUP | EPOLLERR : EPOLLOUT | EPOLLWRNORM;
 225         if (serio_raw->head != serio_raw->tail)
 226                 mask |= EPOLLIN | EPOLLRDNORM;
 227
 228         return mask;
 229 }
 230
 231 static const struct file_operations serio_raw_fops = {
 232         .owner          = THIS_MODULE,
 233         .open           = serio_raw_open,
 234         .release        = serio_raw_release,
 235         .read           = serio_raw_read,
 236         .write          = serio_raw_write,
 237         .poll           = serio_raw_poll,
 238         .fasync         = serio_raw_fasync,
 239         .llseek         = noop_llseek,
 240 };
 241
 242
 243 /*********************************************************************
 244  *                   Interface with serio port                       *
 245  *********************************************************************/
 246
 247 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
 248                                         unsigned int dfl)
 249 {
 250         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 251         struct serio_raw_client *client;
 252         unsigned int head = serio_raw->head;
 253
 254         /* we are holding serio->lock here so we are protected */
 255         serio_raw->queue[head] = data;
 256         head = (head + 1) % SERIO_RAW_QUEUE_LEN;
 257         if (likely(head != serio_raw->tail)) {
 258                 serio_raw->head = head;
 259                 list_for_each_entry(client, &serio_raw->client_list, node)
 260                         kill_fasync(&client->fasync, SIGIO, POLL_IN);
 261                 wake_up_interruptible(&serio_raw->wait);
 262         }
 263
 264         return IRQ_HANDLED;
 265 }
 266
 267 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
 268 {
 269         static atomic_t serio_raw_no = ATOMIC_INIT(-1);
 270         struct serio_raw *serio_raw;
 271         int err;
 272
 273         serio_raw = kzalloc(sizeof(*serio_raw), GFP_KERNEL);
 274         if (!serio_raw) {
 275                 dev_dbg(&serio->dev, "can't allocate memory for a device\n");
 276                 return -ENOMEM;
 277         }
 278
 279         snprintf(serio_raw->name, sizeof(serio_raw->name),
 280                  "serio_raw%u", atomic_inc_return(&serio_raw_no));
 281         kref_init(&serio_raw->kref);
 282         INIT_LIST_HEAD(&serio_raw->client_list);
 283         init_waitqueue_head(&serio_raw->wait);
 284
 285         serio_raw->serio = serio;
 286         get_device(&serio->dev);
 287
 288         serio_set_drvdata(serio, serio_raw);
 289
 290         err = serio_open(serio, drv);
 291         if (err)
 292                 goto err_free;
 293
 294         err = mutex_lock_killable(&serio_raw_mutex);
 295         if (err)
 296                 goto err_close;
 297
 298         list_add_tail(&serio_raw->node, &serio_raw_list);
 299         mutex_unlock(&serio_raw_mutex);
 300
 301         serio_raw->dev.minor = PSMOUSE_MINOR;
 302         serio_raw->dev.name = serio_raw->name;
 303         serio_raw->dev.parent = &serio->dev;
 304         serio_raw->dev.fops = &serio_raw_fops;
 305
 306         err = misc_register(&serio_raw->dev);
 307         if (err) {
 308                 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
 309                 err = misc_register(&serio_raw->dev);
 310         }
 311
 312         if (err) {
 313                 dev_err(&serio->dev,
 314                         "failed to register raw access device for %s\n",
 315                         serio->phys);
 316                 goto err_unlink;
 317         }
 318
 319         dev_info(&serio->dev, "raw access enabled on %s (%s, minor %d)\n",
 320                  serio->phys, serio_raw->name, serio_raw->dev.minor);
 321         return 0;
 322
 323 err_unlink:
 324         list_del_init(&serio_raw->node);
 325 err_close:
 326         serio_close(serio);
 327 err_free:
 328         serio_set_drvdata(serio, NULL);
 329         kref_put(&serio_raw->kref, serio_raw_free);
 330         return err;
 331 }
 332
 333 static int serio_raw_reconnect(struct serio *serio)
 334 {
 335         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 336         struct serio_driver *drv = serio->drv;
 337
 338         if (!drv || !serio_raw) {
 339                 dev_dbg(&serio->dev,
 340                         "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 /*
 352  * Wake up users waiting for IO so they can disconnect from
 353  * dead device.
 354  */
 355 static void serio_raw_hangup(struct serio_raw *serio_raw)
 356 {
 357         struct serio_raw_client *client;
 358
 359         scoped_guard(serio_pause_rx, serio_raw->serio) {
 360                 list_for_each_entry(client, &serio_raw->client_list, node)
 361                         kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 362         }
 363
 364         wake_up_interruptible(&serio_raw->wait);
 365 }
 366
 367
 368 static void serio_raw_disconnect(struct serio *serio)
 369 {
 370         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 371
 372         misc_deregister(&serio_raw->dev);
 373
 374         scoped_guard(mutex, &serio_raw_mutex) {
 375                 serio_raw->dead = true;
 376                 list_del_init(&serio_raw->node);
 377         }
 378
 379         serio_raw_hangup(serio_raw);
 380
 381         serio_close(serio);
 382         kref_put(&serio_raw->kref, serio_raw_free);
 383
 384         serio_set_drvdata(serio, NULL);
 385 }
 386
 387 static const struct serio_device_id serio_raw_serio_ids[] = {
 388         {
 389                 .type   = SERIO_8042,
 390                 .proto  = SERIO_ANY,
 391                 .id     = SERIO_ANY,
 392                 .extra  = SERIO_ANY,
 393         },
 394         {
 395                 .type   = SERIO_8042_XL,
 396                 .proto  = SERIO_ANY,
 397                 .id     = SERIO_ANY,
 398                 .extra  = SERIO_ANY,
 399         },
 400         { 0 }
 401 };
 402
 403 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
 404
 405 static struct serio_driver serio_raw_drv = {
 406         .driver         = {
 407                 .name   = "serio_raw",
 408         },
 409         .description    = DRIVER_DESC,
 410         .id_table       = serio_raw_serio_ids,
 411         .interrupt      = serio_raw_interrupt,
 412         .connect        = serio_raw_connect,
 413         .reconnect      = serio_raw_reconnect,
 414         .disconnect     = serio_raw_disconnect,
 415         .manual_bind    = true,
 416 };
 417
 418 module_serio_driver(serio_raw_drv);