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->scan_progress = 0;
 240         async->munge_chan = 0;
 241         async->munge_count = 0;
 242         async->munge_ptr = 0;
 243
 244         async->events = 0;
 245 }
 246
 247 static unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s)
 248 {
 249         struct comedi_async *async = s->async;
 250         unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
 251
 252         return free_end - async->buf_write_alloc_count;
 253 }
 254
 255 static unsigned int __comedi_buf_write_alloc(struct comedi_subdevice *s,
 256                                              unsigned int nbytes,
 257                                              int strict)
 258 {
 259         struct comedi_async *async = s->async;
 260         unsigned int available = comedi_buf_write_n_available(s);
 261
 262         if (nbytes > available)
 263                 nbytes = strict ? 0 : available;
 264
 265         async->buf_write_alloc_count += nbytes;
 266
 267         /*
 268          * ensure the async buffer 'counts' are read and updated
 269          * before we write data to the write-alloc'ed buffer space
 270          */
 271         smp_mb();
 272
 273         return nbytes;
 274 }
 275
 276 /* allocates chunk for the writer from free buffer space */
 277 unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s,
 278                                     unsigned int nbytes)
 279 {
 280         return __comedi_buf_write_alloc(s, nbytes, 0);
 281 }
 282 EXPORT_SYMBOL_GPL(comedi_buf_write_alloc);
 283
 284 /*
 285  * munging is applied to data by core as it passes between user
 286  * and kernel space
 287  */
 288 static unsigned int comedi_buf_munge(struct comedi_subdevice *s,
 289                                      unsigned int num_bytes)
 290 {
 291         struct comedi_async *async = s->async;
 292         unsigned int count = 0;
 293         const unsigned num_sample_bytes = bytes_per_sample(s);
 294
 295         if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {
 296                 async->munge_count += num_bytes;
 297                 count = num_bytes;
 298         } else {
 299                 /* don't munge partial samples */
 300                 num_bytes -= num_bytes % num_sample_bytes;
 301                 while (count < num_bytes) {
 302                         int block_size = num_bytes - count;
 303                         unsigned int buf_end;
 304
 305                         buf_end = async->prealloc_bufsz - async->munge_ptr;
 306                         if (block_size > buf_end)
 307                                 block_size = buf_end;
 308
 309                         s->munge(s->device, s,
 310                                  async->prealloc_buf + async->munge_ptr,
 311                                  block_size, async->munge_chan);
 312
 313                         /*
 314                          * ensure data is munged in buffer before the
 315                          * async buffer munge_count is incremented
 316                          */
 317                         smp_wmb();
 318
 319                         async->munge_chan += block_size / num_sample_bytes;
 320                         async->munge_chan %= async->cmd.chanlist_len;
 321                         async->munge_count += block_size;
 322                         async->munge_ptr += block_size;
 323                         async->munge_ptr %= async->prealloc_bufsz;
 324                         count += block_size;
 325                 }
 326         }
 327
 328         return count;
 329 }
 330
 331 unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s)
 332 {
 333         struct comedi_async *async = s->async;
 334
 335         return async->buf_write_alloc_count - async->buf_write_count;
 336 }
 337
 338 /* transfers a chunk from writer to filled buffer space */
 339 unsigned int comedi_buf_write_free(struct comedi_subdevice *s,
 340                                    unsigned int nbytes)
 341 {
 342         struct comedi_async *async = s->async;
 343         unsigned int allocated = comedi_buf_write_n_allocated(s);
 344
 345         if (nbytes > allocated)
 346                 nbytes = allocated;
 347
 348         async->buf_write_count += nbytes;
 349         async->buf_write_ptr += nbytes;
 350         comedi_buf_munge(s, async->buf_write_count - async->munge_count);
 351         if (async->buf_write_ptr >= async->prealloc_bufsz)
 352                 async->buf_write_ptr %= async->prealloc_bufsz;
 353
 354         return nbytes;
 355 }
 356 EXPORT_SYMBOL_GPL(comedi_buf_write_free);
 357
 358 unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s)
 359 {
 360         struct comedi_async *async = s->async;
 361         unsigned num_bytes;
 362
 363         if (!async)
 364                 return 0;
 365
 366         num_bytes = async->munge_count - async->buf_read_count;
 367
 368         /*
 369          * ensure the async buffer 'counts' are read before we
 370          * attempt to read data from the buffer
 371          */
 372         smp_rmb();
 373
 374         return num_bytes;
 375 }
 376 EXPORT_SYMBOL_GPL(comedi_buf_read_n_available);
 377
 378 /* allocates a chunk for the reader from filled (and munged) buffer space */
 379 unsigned int comedi_buf_read_alloc(struct comedi_subdevice *s,
 380                                    unsigned int nbytes)
 381 {
 382         struct comedi_async *async = s->async;
 383         unsigned int available;
 384
 385         available = async->munge_count - async->buf_read_alloc_count;
 386         if (nbytes > available)
 387                 nbytes = available;
 388
 389         async->buf_read_alloc_count += nbytes;
 390
 391         /*
 392          * ensure the async buffer 'counts' are read before we
 393          * attempt to read data from the read-alloc'ed buffer space
 394          */
 395         smp_rmb();
 396
 397         return nbytes;
 398 }
 399 EXPORT_SYMBOL_GPL(comedi_buf_read_alloc);
 400
 401 static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async)
 402 {
 403         return async->buf_read_alloc_count - async->buf_read_count;
 404 }
 405
 406 /* transfers control of a chunk from reader to free buffer space */
 407 unsigned int comedi_buf_read_free(struct comedi_subdevice *s,
 408                                   unsigned int nbytes)
 409 {
 410         struct comedi_async *async = s->async;
 411         unsigned int allocated;
 412
 413         /*
 414          * ensure data has been read out of buffer before
 415          * the async read count is incremented
 416          */
 417         smp_mb();
 418
 419         allocated = comedi_buf_read_n_allocated(async);
 420         if (nbytes > allocated)
 421                 nbytes = allocated;
 422
 423         async->buf_read_count += nbytes;
 424         async->buf_read_ptr += nbytes;
 425         async->buf_read_ptr %= async->prealloc_bufsz;
 426         return nbytes;
 427 }
 428 EXPORT_SYMBOL_GPL(comedi_buf_read_free);
 429
 430 int comedi_buf_put(struct comedi_subdevice *s, unsigned short x)
 431 {
 432         struct comedi_async *async = s->async;
 433         unsigned int n = __comedi_buf_write_alloc(s, sizeof(short), 1);
 434
 435         if (n < sizeof(short)) {
 436                 async->events |= COMEDI_CB_ERROR;
 437                 return 0;
 438         }
 439         *(unsigned short *)(async->prealloc_buf + async->buf_write_ptr) = x;
 440         comedi_buf_write_free(s, sizeof(short));
 441         return 1;
 442 }
 443 EXPORT_SYMBOL_GPL(comedi_buf_put);
 444
 445 int comedi_buf_get(struct comedi_subdevice *s, unsigned short *x)
 446 {
 447         struct comedi_async *async = s->async;
 448         unsigned int n = comedi_buf_read_n_available(s);
 449
 450         if (n < sizeof(short))
 451                 return 0;
 452         comedi_buf_read_alloc(s, sizeof(short));
 453         *x = *(unsigned short *)(async->prealloc_buf + async->buf_read_ptr);
 454         comedi_buf_read_free(s, sizeof(short));
 455         return 1;
 456 }
 457 EXPORT_SYMBOL_GPL(comedi_buf_get);
 458
 459 void comedi_buf_memcpy_to(struct comedi_subdevice *s, unsigned int offset,
 460                           const void *data, unsigned int num_bytes)
 461 {
 462         struct comedi_async *async = s->async;
 463         unsigned int write_ptr = async->buf_write_ptr + offset;
 464
 465         if (write_ptr >= async->prealloc_bufsz)
 466                 write_ptr %= async->prealloc_bufsz;
 467
 468         while (num_bytes) {
 469                 unsigned int block_size;
 470
 471                 if (write_ptr + num_bytes > async->prealloc_bufsz)
 472                         block_size = async->prealloc_bufsz - write_ptr;
 473                 else
 474                         block_size = num_bytes;
 475
 476                 memcpy(async->prealloc_buf + write_ptr, data, block_size);
 477
 478                 data += block_size;
 479                 num_bytes -= block_size;
 480
 481                 write_ptr = 0;
 482         }
 483 }
 484 EXPORT_SYMBOL_GPL(comedi_buf_memcpy_to);
 485
 486 void comedi_buf_memcpy_from(struct comedi_subdevice *s, unsigned int offset,
 487                             void *dest, unsigned int nbytes)
 488 {
 489         void *src;
 490         struct comedi_async *async = s->async;
 491         unsigned int read_ptr = async->buf_read_ptr + offset;
 492
 493         if (read_ptr >= async->prealloc_bufsz)
 494                 read_ptr %= async->prealloc_bufsz;
 495
 496         while (nbytes) {
 497                 unsigned int block_size;
 498
 499                 src = async->prealloc_buf + read_ptr;
 500
 501                 if (nbytes >= async->prealloc_bufsz - read_ptr)
 502                         block_size = async->prealloc_bufsz - read_ptr;
 503                 else
 504                         block_size = nbytes;
 505
 506                 memcpy(dest, src, block_size);
 507                 nbytes -= block_size;
 508                 dest += block_size;
 509                 read_ptr = 0;
 510         }
 511 }
 512 EXPORT_SYMBOL_GPL(comedi_buf_memcpy_from);
 513
 514 /**
 515  * comedi_write_array_to_buffer - write data to comedi buffer
 516  * @s: comedi_subdevice struct
 517  * @data: destination
 518  * @num_bytes: number of bytes to write
 519  *
 520  * Writes up to num_bytes bytes of data to the comedi buffer associated with
 521  * the subdevice, marks it as written and updates the acquisition scan
 522  * progress.
 523  *
 524  * Returns the amount of data written in bytes.
 525  */
 526 unsigned int comedi_write_array_to_buffer(struct comedi_subdevice *s,
 527                                           const void *data,
 528                                           unsigned int num_bytes)
 529 {
 530         struct comedi_async *async = s->async;
 531         unsigned int retval;
 532
 533         if (num_bytes == 0)
 534                 return 0;
 535
 536         retval = comedi_buf_write_alloc(s, num_bytes);
 537         if (retval != num_bytes) {
 538                 dev_warn(s->device->class_dev, "buffer overrun\n");
 539                 async->events |= COMEDI_CB_OVERFLOW;
 540                 return 0;
 541         }
 542
 543         comedi_buf_memcpy_to(s, 0, data, num_bytes);
 544         comedi_buf_write_free(s, num_bytes);
 545         comedi_inc_scan_progress(s, num_bytes);
 546         async->events |= COMEDI_CB_BLOCK;
 547
 548         return num_bytes;
 549 }
 550 EXPORT_SYMBOL_GPL(comedi_write_array_to_buffer);
 551
 552 /**
 553  * comedi_read_array_from_buffer - read data from comedi buffer
 554  * @s: comedi_subdevice struct
 555  * @data: destination
 556  * @num_bytes: number of bytes to read
 557  *
 558  * Reads up to num_bytes bytes of data from the comedi buffer associated with
 559  * the subdevice, marks it as read and updates the acquisition scan progress.
 560  *
 561  * Returns the amount of data read in bytes.
 562  */
 563 unsigned int comedi_read_array_from_buffer(struct comedi_subdevice *s,
 564                                            void *data, unsigned int num_bytes)
 565 {
 566         if (num_bytes == 0)
 567                 return 0;
 568
 569         num_bytes = comedi_buf_read_alloc(s, num_bytes);
 570         comedi_buf_memcpy_from(s, 0, data, num_bytes);
 571         comedi_buf_read_free(s, num_bytes);
 572         comedi_inc_scan_progress(s, num_bytes);
 573         s->async->events |= COMEDI_CB_BLOCK;
 574
 575         return num_bytes;
 576 }
 577 EXPORT_SYMBOL_GPL(comedi_read_array_from_buffer);