drivers/hid/uhid.c

   1 /*
   2  * User-space I/O driver support for HID subsystem
   3  * Copyright (c) 2012 David Herrmann
   4  */
   5
   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 as published by the Free
   9  * Software Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  */
  12
  13 #include <linux/atomic.h>
  14 #include <linux/device.h>
  15 #include <linux/fs.h>
  16 #include <linux/hid.h>
  17 #include <linux/input.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/poll.h>
  22 #include <linux/sched.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/uhid.h>
  25 #include <linux/wait.h>
  26
  27 #define UHID_NAME       "uhid"
  28 #define UHID_BUFSIZE    32
  29
  30 struct uhid_device {
  31         struct mutex devlock;
  32         bool running;
  33
  34         __u8 *rd_data;
  35         uint rd_size;
  36
  37         struct hid_device *hid;
  38         struct uhid_event input_buf;
  39
  40         wait_queue_head_t waitq;
  41         spinlock_t qlock;
  42         __u8 head;
  43         __u8 tail;
  44         struct uhid_event *outq[UHID_BUFSIZE];
  45 };
  46
  47 static struct miscdevice uhid_misc;
  48
  49 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
  50 {
  51         __u8 newhead;
  52
  53         newhead = (uhid->head + 1) % UHID_BUFSIZE;
  54
  55         if (newhead != uhid->tail) {
  56                 uhid->outq[uhid->head] = ev;
  57                 uhid->head = newhead;
  58                 wake_up_interruptible(&uhid->waitq);
  59         } else {
  60                 hid_warn(uhid->hid, "Output queue is full\n");
  61                 kfree(ev);
  62         }
  63 }
  64
  65 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
  66 {
  67         unsigned long flags;
  68         struct uhid_event *ev;
  69
  70         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
  71         if (!ev)
  72                 return -ENOMEM;
  73
  74         ev->type = event;
  75
  76         spin_lock_irqsave(&uhid->qlock, flags);
  77         uhid_queue(uhid, ev);
  78         spin_unlock_irqrestore(&uhid->qlock, flags);
  79
  80         return 0;
  81 }
  82
  83 static int uhid_hid_start(struct hid_device *hid)
  84 {
  85         return 0;
  86 }
  87
  88 static void uhid_hid_stop(struct hid_device *hid)
  89 {
  90 }
  91
  92 static int uhid_hid_open(struct hid_device *hid)
  93 {
  94         return 0;
  95 }
  96
  97 static void uhid_hid_close(struct hid_device *hid)
  98 {
  99 }
 100
 101 static int uhid_hid_input(struct input_dev *input, unsigned int type,
 102                           unsigned int code, int value)
 103 {
 104         return 0;
 105 }
 106
 107 static int uhid_hid_parse(struct hid_device *hid)
 108 {
 109         return 0;
 110 }
 111
 112 static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
 113                             __u8 *buf, size_t count, unsigned char rtype)
 114 {
 115         return 0;
 116 }
 117
 118 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
 119                                unsigned char report_type)
 120 {
 121         return 0;
 122 }
 123
 124 static struct hid_ll_driver uhid_hid_driver = {
 125         .start = uhid_hid_start,
 126         .stop = uhid_hid_stop,
 127         .open = uhid_hid_open,
 128         .close = uhid_hid_close,
 129         .hidinput_input_event = uhid_hid_input,
 130         .parse = uhid_hid_parse,
 131 };
 132
 133 static int uhid_dev_create(struct uhid_device *uhid,
 134                            const struct uhid_event *ev)
 135 {
 136         struct hid_device *hid;
 137         int ret;
 138
 139         if (uhid->running)
 140                 return -EALREADY;
 141
 142         uhid->rd_size = ev->u.create.rd_size;
 143         if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
 144                 return -EINVAL;
 145
 146         uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
 147         if (!uhid->rd_data)
 148                 return -ENOMEM;
 149
 150         if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
 151                            uhid->rd_size)) {
 152                 ret = -EFAULT;
 153                 goto err_free;
 154         }
 155
 156         hid = hid_allocate_device();
 157         if (IS_ERR(hid)) {
 158                 ret = PTR_ERR(hid);
 159                 goto err_free;
 160         }
 161
 162         strncpy(hid->name, ev->u.create.name, 127);
 163         hid->name[127] = 0;
 164         strncpy(hid->phys, ev->u.create.phys, 63);
 165         hid->phys[63] = 0;
 166         strncpy(hid->uniq, ev->u.create.uniq, 63);
 167         hid->uniq[63] = 0;
 168
 169         hid->ll_driver = &uhid_hid_driver;
 170         hid->hid_get_raw_report = uhid_hid_get_raw;
 171         hid->hid_output_raw_report = uhid_hid_output_raw;
 172         hid->bus = ev->u.create.bus;
 173         hid->vendor = ev->u.create.vendor;
 174         hid->product = ev->u.create.product;
 175         hid->version = ev->u.create.version;
 176         hid->country = ev->u.create.country;
 177         hid->driver_data = uhid;
 178         hid->dev.parent = uhid_misc.this_device;
 179
 180         uhid->hid = hid;
 181         uhid->running = true;
 182
 183         ret = hid_add_device(hid);
 184         if (ret) {
 185                 hid_err(hid, "Cannot register HID device\n");
 186                 goto err_hid;
 187         }
 188
 189         return 0;
 190
 191 err_hid:
 192         hid_destroy_device(hid);
 193         uhid->hid = NULL;
 194         uhid->running = false;
 195 err_free:
 196         kfree(uhid->rd_data);
 197         return ret;
 198 }
 199
 200 static int uhid_dev_destroy(struct uhid_device *uhid)
 201 {
 202         if (!uhid->running)
 203                 return -EINVAL;
 204
 205         uhid->running = false;
 206
 207         hid_destroy_device(uhid->hid);
 208         kfree(uhid->rd_data);
 209
 210         return 0;
 211 }
 212
 213 static int uhid_char_open(struct inode *inode, struct file *file)
 214 {
 215         struct uhid_device *uhid;
 216
 217         uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
 218         if (!uhid)
 219                 return -ENOMEM;
 220
 221         mutex_init(&uhid->devlock);
 222         spin_lock_init(&uhid->qlock);
 223         init_waitqueue_head(&uhid->waitq);
 224         uhid->running = false;
 225
 226         file->private_data = uhid;
 227         nonseekable_open(inode, file);
 228
 229         return 0;
 230 }
 231
 232 static int uhid_char_release(struct inode *inode, struct file *file)
 233 {
 234         struct uhid_device *uhid = file->private_data;
 235         unsigned int i;
 236
 237         uhid_dev_destroy(uhid);
 238
 239         for (i = 0; i < UHID_BUFSIZE; ++i)
 240                 kfree(uhid->outq[i]);
 241
 242         kfree(uhid);
 243
 244         return 0;
 245 }
 246
 247 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
 248                                 size_t count, loff_t *ppos)
 249 {
 250         struct uhid_device *uhid = file->private_data;
 251         int ret;
 252         unsigned long flags;
 253         size_t len;
 254
 255         /* they need at least the "type" member of uhid_event */
 256         if (count < sizeof(__u32))
 257                 return -EINVAL;
 258
 259 try_again:
 260         if (file->f_flags & O_NONBLOCK) {
 261                 if (uhid->head == uhid->tail)
 262                         return -EAGAIN;
 263         } else {
 264                 ret = wait_event_interruptible(uhid->waitq,
 265                                                 uhid->head != uhid->tail);
 266                 if (ret)
 267                         return ret;
 268         }
 269
 270         ret = mutex_lock_interruptible(&uhid->devlock);
 271         if (ret)
 272                 return ret;
 273
 274         if (uhid->head == uhid->tail) {
 275                 mutex_unlock(&uhid->devlock);
 276                 goto try_again;
 277         } else {
 278                 len = min(count, sizeof(**uhid->outq));
 279                 if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) {
 280                         ret = -EFAULT;
 281                 } else {
 282                         kfree(uhid->outq[uhid->tail]);
 283                         uhid->outq[uhid->tail] = NULL;
 284
 285                         spin_lock_irqsave(&uhid->qlock, flags);
 286                         uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
 287                         spin_unlock_irqrestore(&uhid->qlock, flags);
 288                 }
 289         }
 290
 291         mutex_unlock(&uhid->devlock);
 292         return ret ? ret : len;
 293 }
 294
 295 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
 296                                 size_t count, loff_t *ppos)
 297 {
 298         struct uhid_device *uhid = file->private_data;
 299         int ret;
 300         size_t len;
 301
 302         /* we need at least the "type" member of uhid_event */
 303         if (count < sizeof(__u32))
 304                 return -EINVAL;
 305
 306         ret = mutex_lock_interruptible(&uhid->devlock);
 307         if (ret)
 308                 return ret;
 309
 310         memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
 311         len = min(count, sizeof(uhid->input_buf));
 312         if (copy_from_user(&uhid->input_buf, buffer, len)) {
 313                 ret = -EFAULT;
 314                 goto unlock;
 315         }
 316
 317         switch (uhid->input_buf.type) {
 318         case UHID_CREATE:
 319                 ret = uhid_dev_create(uhid, &uhid->input_buf);
 320                 break;
 321         case UHID_DESTROY:
 322                 ret = uhid_dev_destroy(uhid);
 323                 break;
 324         default:
 325                 ret = -EOPNOTSUPP;
 326         }
 327
 328 unlock:
 329         mutex_unlock(&uhid->devlock);
 330
 331         /* return "count" not "len" to not confuse the caller */
 332         return ret ? ret : count;
 333 }
 334
 335 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
 336 {
 337         struct uhid_device *uhid = file->private_data;
 338
 339         poll_wait(file, &uhid->waitq, wait);
 340
 341         if (uhid->head != uhid->tail)
 342                 return POLLIN | POLLRDNORM;
 343
 344         return 0;
 345 }
 346
 347 static const struct file_operations uhid_fops = {
 348         .owner          = THIS_MODULE,
 349         .open           = uhid_char_open,
 350         .release        = uhid_char_release,
 351         .read           = uhid_char_read,
 352         .write          = uhid_char_write,
 353         .poll           = uhid_char_poll,
 354         .llseek         = no_llseek,
 355 };
 356
 357 static struct miscdevice uhid_misc = {
 358         .fops           = &uhid_fops,
 359         .minor          = MISC_DYNAMIC_MINOR,
 360         .name           = UHID_NAME,
 361 };
 362
 363 static int __init uhid_init(void)
 364 {
 365         return misc_register(&uhid_misc);
 366 }
 367
 368 static void __exit uhid_exit(void)
 369 {
 370         misc_deregister(&uhid_misc);
 371 }
 372
 373 module_init(uhid_init);
 374 module_exit(uhid_exit);
 375 MODULE_LICENSE("GPL");
 376 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
 377 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");