drivers/staging/comedi/comedi_buf.c

   1 /*
   2  * comedi_buf.c
   3  *
   4  * COMEDI - Linux Control and Measurement Device Interface
   5  * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
   6  * Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  */
  18
  19 #include <linux/vmalloc.h>
  20 #include <linux/slab.h>
  21
  22 #include "comedidev.h"
  23 #include "comedi_internal.h"
  24
  25 #ifdef PAGE_KERNEL_NOCACHE
  26 #define COMEDI_PAGE_PROTECTION          PAGE_KERNEL_NOCACHE
  27 #else
  28 #define COMEDI_PAGE_PROTECTION          PAGE_KERNEL
  29 #endif
  30
  31 static void comedi_buf_map_kref_release(struct kref *kref)
  32 {
  33         struct comedi_buf_map *bm =
  34                 container_of(kref, struct comedi_buf_map, refcount);
  35         struct comedi_buf_page *buf;
  36         unsigned int i;
  37
  38         if (bm->page_list) {
  39                 for (i = 0; i < bm->n_pages; i++) {
  40                         buf = &bm->page_list[i];
  41                         clear_bit(PG_reserved,
  42                                   &(virt_to_page(buf->virt_addr)->flags));
  43                         if (bm->dma_dir != DMA_NONE) {
  44 #ifdef CONFIG_HAS_DMA
  45                                 dma_free_coherent(bm->dma_hw_dev,
  46                                                   PAGE_SIZE,
  47                                                   buf->virt_addr,
  48                                                   buf->dma_addr);
  49 #endif
  50                         } else {
  51                                 free_page((unsigned long)buf->virt_addr);
  52                         }
  53                 }
  54                 vfree(bm->page_list);
  55         }
  56         if (bm->dma_dir != DMA_NONE)
  57                 put_device(bm->dma_hw_dev);
  58         kfree(bm);
  59 }
  60
  61 static void __comedi_buf_free(struct comedi_device *dev,
  62                               struct comedi_subdevice *s)
  63 {
  64         struct comedi_async *async = s->async;
  65         struct comedi_buf_map *bm;
  66         unsigned long flags;
  67
  68         if (async->prealloc_buf) {
  69                 vunmap(async->prealloc_buf);
  70                 async->prealloc_buf = NULL;
  71                 async->prealloc_bufsz = 0;
  72         }
  73
  74         spin_lock_irqsave(&s->spin_lock, flags);
  75         bm = async->buf_map;
  76         async->buf_map = NULL;
  77         spin_unlock_irqrestore(&s->spin_lock, flags);
  78         comedi_buf_map_put(bm);
  79 }
  80
  81 static void __comedi_buf_alloc(struct comedi_device *dev,
  82                                struct comedi_subdevice *s,
  83                                unsigned n_pages)
  84 {
  85         struct comedi_async *async = s->async;
  86         struct page **pages = NULL;
  87         struct comedi_buf_map *bm;
  88         struct comedi_buf_page *buf;
  89         unsigned long flags;
  90         unsigned i;
  91
  92         if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {
  93                 dev_err(dev->class_dev,
  94                         "dma buffer allocation not supported\n");
  95                 return;
  96         }
  97
  98         bm = kzalloc(sizeof(*async->buf_map), GFP_KERNEL);
  99         if (!bm)
 100                 return;
 101
 102         kref_init(&bm->refcount);
 103         spin_lock_irqsave(&s->spin_lock, flags);
 104         async->buf_map = bm;
 105         spin_unlock_irqrestore(&s->spin_lock, flags);
 106         bm->dma_dir = s->async_dma_dir;
 107         if (bm->dma_dir != DMA_NONE)
 108                 /* Need ref to hardware device to free buffer later. */
 109                 bm->dma_hw_dev = get_device(dev->hw_dev);
 110
 111         bm->page_list = vzalloc(sizeof(*buf) * n_pages);
 112         if (bm->page_list)
 113                 pages = vmalloc(sizeof(struct page *) * n_pages);
 114
 115         if (!pages)
 116                 return;
 117
 118         for (i = 0; i < n_pages; i++) {
 119                 buf = &bm->page_list[i];
 120                 if (bm->dma_dir != DMA_NONE)
 121 #ifdef CONFIG_HAS_DMA
 122                         buf->virt_addr = dma_alloc_coherent(bm->dma_hw_dev,
 123                                                             PAGE_SIZE,
 124                                                             &buf->dma_addr,
 125                                                             GFP_KERNEL |
 126                                                             __GFP_COMP);
 127 #else
 128                         break;
 129 #endif
 130                 else
 131                         buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);
 132                 if (!buf->virt_addr)
 133                         break;
 134
 135                 set_bit(PG_reserved, &(virt_to_page(buf->virt_addr)->flags));
 136
 137                 pages[i] = virt_to_page(buf->virt_addr);
 138         }
 139         spin_lock_irqsave(&s->spin_lock, flags);
 140         bm->n_pages = i;
 141         spin_unlock_irqrestore(&s->spin_lock, flags);
 142
 143         /* vmap the prealloc_buf if all the pages were allocated */
 144         if (i == n_pages)
 145                 async->prealloc_buf = vmap(pages, n_pages, VM_MAP,
 146                                            COMEDI_PAGE_PROTECTION);
 147
 148         vfree(pages);
 149 }
 150
 151 void comedi_buf_map_get(struct comedi_buf_map *bm)
 152 {
 153         if (bm)
 154                 kref_get(&bm->refcount);
 155 }
 156
 157 int comedi_buf_map_put(struct comedi_buf_map *bm)
 158 {
 159         if (bm)
 160                 return kref_put(&bm->refcount, comedi_buf_map_kref_release);
 161         return 1;
 162 }
 163
 164 /* returns s->async->buf_map and increments its kref refcount */
 165 struct comedi_buf_map *
 166 comedi_buf_map_from_subdev_get(struct comedi_subdevice *s)
 167 {
 168         struct comedi_async *async = s->async;
 169         struct comedi_buf_map *bm = NULL;
 170         unsigned long flags;
 171
 172         if (!async)
 173                 return NULL;
 174
 175         spin_lock_irqsave(&s->spin_lock, flags);
 176         bm = async->buf_map;
 177         /* only want it if buffer pages allocated */
 178         if (bm && bm->n_pages)
 179                 comedi_buf_map_get(bm);
 180         else
 181                 bm = NULL;
 182         spin_unlock_irqrestore(&s->spin_lock, flags);
 183
 184         return bm;
 185 }
 186
 187 bool comedi_buf_is_mmapped(struct comedi_subdevice *s)
 188 {
 189         struct comedi_buf_map *bm = s->async->buf_map;
 190
 191         return bm && (atomic_read(&bm->refcount.refcount) > 1);
 192 }
 193
 194 int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
 195                      unsigned long new_size)
 196 {
 197         struct comedi_async *async = s->async;
 198
 199         /* Round up new_size to multiple of PAGE_SIZE */
 200         new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;
 201
 202         /* if no change is required, do nothing */
 203         if (async->prealloc_buf && async->prealloc_bufsz == new_size)
 204                 return 0;
 205
 206         /* deallocate old buffer */
 207         __comedi_buf_free(dev, s);
 208
 209         /* allocate new buffer */
 210         if (new_size) {
 211                 unsigned n_pages = new_size >> PAGE_SHIFT;
 212
 213                 __comedi_buf_alloc(dev, s, n_pages);
 214
 215                 if (!async->prealloc_buf) {
 216                         /* allocation failed */
 217                         __comedi_buf_free(dev, s);
 218                         return -ENOMEM;
 219                 }
 220         }
 221         async->prealloc_bufsz = new_size;
 222
 223         return 0;
 224 }
 225
 226 void comedi_buf_reset(struct comedi_subdevice *s)
 227 {
 228         struct comedi_async *async = s->async;
 229
 230         async->buf_write_alloc_count = 0;
 231         async->buf_write_count = 0;
 232         async->buf_read_alloc_count = 0;
 233         async->buf_read_count = 0;
 234
 235         async->buf_write_ptr = 0;
 236         async->buf_read_ptr = 0;
 237
 238         async->cur_chan = 0;
 239         async->scans_done = 0;
 240         async->scan_progress = 0;
 241         async->munge_chan = 0;
 242         async->munge_count = 0;
 243         async->munge_ptr = 0;
 244
 245         async->events = 0;
 246 }
 247
 248 static unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s)
 249 {
 250         struct comedi_async *async = s->async;
 251         unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
 252
 253         return free_end - async->buf_write_alloc_count;
 254 }
 255
 256 /* allocates chunk for the writer from free buffer space */
 257 unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s,
 258                                     unsigned int nbytes)
 259 {
 260         struct comedi_async *async = s->async;
 261         unsigned int available = comedi_buf_write_n_available(s);
 262
 263         if (nbytes > available)
 264                 nbytes = available;
 265
 266         async->buf_write_alloc_count += nbytes;
 267
 268         /*
 269          * ensure the async buffer 'counts' are read and updated
 270          * before we write data to the write-alloc'ed buffer space
 271          */
 272         smp_mb();
 273
 274         return nbytes;
 275 }
 276 EXPORT_SYMBOL_GPL(comedi_buf_write_alloc);
 277
 278 /*
 279  * munging is applied to data by core as it passes between user
 280  * and kernel space
 281  */
 282 static unsigned int comedi_buf_munge(struct comedi_subdevice *s,
 283                                      unsigned int num_bytes)
 284 {
 285         struct comedi_async *async = s->async;
 286         unsigned int count = 0;
 287         const unsigned num_sample_bytes = comedi_bytes_per_sample(s);
 288
 289         if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {
 290                 async->munge_count += num_bytes;
 291                 count = num_bytes;
 292         } else {
 293                 /* don't munge partial samples */
 294                 num_bytes -= num_bytes % num_sample_bytes;
 295                 while (count < num_bytes) {
 296                         int block_size = num_bytes - count;
 297                         unsigned int buf_end;
 298
 299                         buf_end = async->prealloc_bufsz - async->munge_ptr;
 300                         if (block_size > buf_end)
 301                                 block_size = buf_end;
 302
 303                         s->munge(s->device, s,
 304                                  async->prealloc_buf + async->munge_ptr,
 305                                  block_size, async->munge_chan);
 306
 307                         /*
 308                          * ensure data is munged in buffer before the
 309                          * async buffer munge_count is incremented
 310                          */
 311                         smp_wmb();
 312
 313                         async->munge_chan += block_size / num_sample_bytes;
 314                         async->munge_chan %= async->cmd.chanlist_len;
 315                         async->munge_count += block_size;
 316                         async->munge_ptr += block_size;
 317                         async->munge_ptr %= async->prealloc_bufsz;
 318                         count += block_size;
 319                 }
 320         }
 321
 322         return count;
 323 }
 324
 325 unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s)
 326 {
 327         struct comedi_async *async = s->async;
 328
 329         return async->buf_write_alloc_count - async->buf_write_count;
 330 }
 331
 332 /* transfers a chunk from writer to filled buffer space */
 333 unsigned int comedi_buf_write_free(struct comedi_subdevice *s,
 334                                    unsigned int nbytes)
 335 {
 336         struct comedi_async *async = s->async;
 337         unsigned int allocated = comedi_buf_write_n_allocated(s);
 338
 339         if (nbytes > allocated)
 340                 nbytes = allocated;
 341
 342         async->buf_write_count += nbytes;
 343         async->buf_write_ptr += nbytes;
 344         comedi_buf_munge(s, async->buf_write_count - async->munge_count);
 345         if (async->buf_write_ptr >= async->prealloc_bufsz)
 346                 async->buf_write_ptr %= async->prealloc_bufsz;
 347
 348         return nbytes;
 349 }
 350 EXPORT_SYMBOL_GPL(comedi_buf_write_free);
 351
 352 unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s)
 353 {
 354         struct comedi_async *async = s->async;
 355         unsigned num_bytes;
 356
 357         if (!async)
 358                 return 0;
 359
 360         num_bytes = async->munge_count - async->buf_read_count;
 361
 362         /*
 363          * ensure the async buffer 'counts' are read before we
 364          * attempt to read data from the buffer
 365          */
 366         smp_rmb();
 367
 368         return num_bytes;
 369 }
 370 EXPORT_SYMBOL_GPL(comedi_buf_read_n_available);
 371
 372 /* allocates a chunk for the reader from filled (and munged) buffer space */
 373 unsigned int comedi_buf_read_alloc(struct comedi_subdevice *s,
 374                                    unsigned int nbytes)
 375 {
 376         struct comedi_async *async = s->async;
 377         unsigned int available;
 378
 379         available = async->munge_count - async->buf_read_alloc_count;
 380         if (nbytes > available)
 381                 nbytes = available;
 382
 383         async->buf_read_alloc_count += nbytes;
 384
 385         /*
 386          * ensure the async buffer 'counts' are read before we
 387          * attempt to read data from the read-alloc'ed buffer space
 388          */
 389         smp_rmb();
 390
 391         return nbytes;
 392 }
 393 EXPORT_SYMBOL_GPL(comedi_buf_read_alloc);
 394
 395 static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async)
 396 {
 397         return async->buf_read_alloc_count - async->buf_read_count;
 398 }
 399
 400 /* transfers control of a chunk from reader to free buffer space */
 401 unsigned int comedi_buf_read_free(struct comedi_subdevice *s,
 402                                   unsigned int nbytes)
 403 {
 404         struct comedi_async *async = s->async;
 405         unsigned int allocated;
 406
 407         /*
 408          * ensure data has been read out of buffer before
 409          * the async read count is incremented
 410          */
 411         smp_mb();
 412
 413         allocated = comedi_buf_read_n_allocated(async);
 414         if (nbytes > allocated)
 415                 nbytes = allocated;
 416
 417         async->buf_read_count += nbytes;
 418         async->buf_read_ptr += nbytes;
 419         async->buf_read_ptr %= async->prealloc_bufsz;
 420         return nbytes;
 421 }
 422 EXPORT_SYMBOL_GPL(comedi_buf_read_free);
 423
 424 static void comedi_buf_memcpy_to(struct comedi_subdevice *s,
 425                                  const void *data, unsigned int num_bytes)
 426 {
 427         struct comedi_async *async = s->async;
 428         unsigned int write_ptr = async->buf_write_ptr;
 429
 430         while (num_bytes) {
 431                 unsigned int block_size;
 432
 433                 if (write_ptr + num_bytes > async->prealloc_bufsz)
 434                         block_size = async->prealloc_bufsz - write_ptr;
 435                 else
 436                         block_size = num_bytes;
 437
 438                 memcpy(async->prealloc_buf + write_ptr, data, block_size);
 439
 440                 data += block_size;
 441                 num_bytes -= block_size;
 442
 443                 write_ptr = 0;
 444         }
 445 }
 446
 447 static void comedi_buf_memcpy_from(struct comedi_subdevice *s,
 448                                    void *dest, unsigned int nbytes)
 449 {
 450         void *src;
 451         struct comedi_async *async = s->async;
 452         unsigned int read_ptr = async->buf_read_ptr;
 453
 454         while (nbytes) {
 455                 unsigned int block_size;
 456
 457                 src = async->prealloc_buf + read_ptr;
 458
 459                 if (nbytes >= async->prealloc_bufsz - read_ptr)
 460                         block_size = async->prealloc_bufsz - read_ptr;
 461                 else
 462                         block_size = nbytes;
 463
 464                 memcpy(dest, src, block_size);
 465                 nbytes -= block_size;
 466                 dest += block_size;
 467                 read_ptr = 0;
 468         }
 469 }
 470
 471 /**
 472  * comedi_buf_write_samples - write sample data to comedi buffer
 473  * @s: comedi_subdevice struct
 474  * @data: samples
 475  * @nsamples: number of samples
 476  *
 477  * Writes nsamples to the comedi buffer associated with the subdevice, marks
 478  * it as written and updates the acquisition scan progress.
 479  *
 480  * Returns the amount of data written in bytes.
 481  */
 482 unsigned int comedi_buf_write_samples(struct comedi_subdevice *s,
 483                                       const void *data, unsigned int nsamples)
 484 {
 485         unsigned int max_samples;
 486         unsigned int nbytes;
 487
 488         /*
 489          * Make sure there is enough room in the buffer for all the samples.
 490          * If not, clamp the nsamples to the number that will fit, flag the
 491          * buffer overrun and add the samples that fit.
 492          */
 493         max_samples = comedi_bytes_to_samples(s,
 494                                               comedi_buf_write_n_available(s));
 495         if (nsamples > max_samples) {
 496                 dev_warn(s->device->class_dev, "buffer overrun\n");
 497                 s->async->events |= COMEDI_CB_OVERFLOW;
 498                 nsamples = max_samples;
 499         }
 500
 501         if (nsamples == 0)
 502                 return 0;
 503
 504         nbytes = comedi_buf_write_alloc(s,
 505                                         comedi_samples_to_bytes(s, nsamples));
 506         comedi_buf_memcpy_to(s, data, nbytes);
 507         comedi_buf_write_free(s, nbytes);
 508         comedi_inc_scan_progress(s, nbytes);
 509         s->async->events |= COMEDI_CB_BLOCK;
 510
 511         return nbytes;
 512 }
 513 EXPORT_SYMBOL_GPL(comedi_buf_write_samples);
 514
 515 /**
 516  * comedi_buf_read_samples - read sample data from comedi buffer
 517  * @s: comedi_subdevice struct
 518  * @data: destination
 519  * @nsamples: maximum number of samples to read
 520  *
 521  * Reads up to nsamples from the comedi buffer associated with the subdevice,
 522  * marks it as read and updates the acquisition scan progress.
 523  *
 524  * Returns the amount of data read in bytes.
 525  */
 526 unsigned int comedi_buf_read_samples(struct comedi_subdevice *s,
 527                                      void *data, unsigned int nsamples)
 528 {
 529         unsigned int max_samples;
 530         unsigned int nbytes;
 531
 532         /* clamp nsamples to the number of full samples available */
 533         max_samples = comedi_bytes_to_samples(s,
 534                                               comedi_buf_read_n_available(s));
 535         if (nsamples > max_samples)
 536                 nsamples = max_samples;
 537
 538         if (nsamples == 0)
 539                 return 0;
 540
 541         nbytes = comedi_buf_read_alloc(s,
 542                                        comedi_samples_to_bytes(s, nsamples));
 543         comedi_buf_memcpy_from(s, data, nbytes);
 544         comedi_buf_read_free(s, nbytes);
 545         comedi_inc_scan_progress(s, nbytes);
 546         s->async->events |= COMEDI_CB_BLOCK;
 547
 548         return nbytes;
 549 }
 550 EXPORT_SYMBOL_GPL(comedi_buf_read_samples);