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  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/vmalloc.h>
  19
  20 #include "comedidev.h"
  21 #include "comedi_internal.h"
  22
  23 #ifdef PAGE_KERNEL_NOCACHE
  24 #define COMEDI_PAGE_PROTECTION          PAGE_KERNEL_NOCACHE
  25 #else
  26 #define COMEDI_PAGE_PROTECTION          PAGE_KERNEL
  27 #endif
  28
  29 static void __comedi_buf_free(struct comedi_device *dev,
  30                               struct comedi_subdevice *s,
  31                               unsigned n_pages)
  32 {
  33         struct comedi_async *async = s->async;
  34         struct comedi_buf_page *buf;
  35         unsigned i;
  36
  37         if (async->prealloc_buf) {
  38                 vunmap(async->prealloc_buf);
  39                 async->prealloc_buf = NULL;
  40                 async->prealloc_bufsz = 0;
  41         }
  42
  43         if (!async->buf_page_list)
  44                 return;
  45
  46         for (i = 0; i < n_pages; ++i) {
  47                 buf = &async->buf_page_list[i];
  48                 if (buf->virt_addr) {
  49                         clear_bit(PG_reserved,
  50                                   &(virt_to_page(buf->virt_addr)->flags));
  51                         if (s->async_dma_dir != DMA_NONE) {
  52 #ifdef CONFIG_HAS_DMA
  53                                 dma_free_coherent(dev->hw_dev,
  54                                                   PAGE_SIZE,
  55                                                   buf->virt_addr,
  56                                                   buf->dma_addr);
  57 #endif
  58                         } else {
  59                                 free_page((unsigned long)buf->virt_addr);
  60                         }
  61                 }
  62         }
  63         vfree(async->buf_page_list);
  64         async->buf_page_list = NULL;
  65         async->n_buf_pages = 0;
  66 }
  67
  68 static void __comedi_buf_alloc(struct comedi_device *dev,
  69                                struct comedi_subdevice *s,
  70                                unsigned n_pages)
  71 {
  72         struct comedi_async *async = s->async;
  73         struct page **pages = NULL;
  74         struct comedi_buf_page *buf;
  75         unsigned i;
  76
  77         if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {
  78                 dev_err(dev->class_dev,
  79                         "dma buffer allocation not supported\n");
  80                 return;
  81         }
  82
  83         async->buf_page_list = vzalloc(sizeof(*buf) * n_pages);
  84         if (async->buf_page_list)
  85                 pages = vmalloc(sizeof(struct page *) * n_pages);
  86
  87         if (!pages)
  88                 return;
  89
  90         for (i = 0; i < n_pages; i++) {
  91                 buf = &async->buf_page_list[i];
  92                 if (s->async_dma_dir != DMA_NONE)
  93 #ifdef CONFIG_HAS_DMA
  94                         buf->virt_addr = dma_alloc_coherent(dev->hw_dev,
  95                                                             PAGE_SIZE,
  96                                                             &buf->dma_addr,
  97                                                             GFP_KERNEL |
  98                                                             __GFP_COMP);
  99 #else
 100                         break;
 101 #endif
 102                 else
 103                         buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);
 104                 if (!buf->virt_addr)
 105                         break;
 106
 107                 set_bit(PG_reserved, &(virt_to_page(buf->virt_addr)->flags));
 108
 109                 pages[i] = virt_to_page(buf->virt_addr);
 110         }
 111
 112         /* vmap the prealloc_buf if all the pages were allocated */
 113         if (i == n_pages)
 114                 async->prealloc_buf = vmap(pages, n_pages, VM_MAP,
 115                                            COMEDI_PAGE_PROTECTION);
 116
 117         vfree(pages);
 118 }
 119
 120 int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
 121                      unsigned long new_size)
 122 {
 123         struct comedi_async *async = s->async;
 124
 125         /* Round up new_size to multiple of PAGE_SIZE */
 126         new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;
 127
 128         /* if no change is required, do nothing */
 129         if (async->prealloc_buf && async->prealloc_bufsz == new_size)
 130                 return 0;
 131
 132         /* deallocate old buffer */
 133         __comedi_buf_free(dev, s, async->n_buf_pages);
 134
 135         /* allocate new buffer */
 136         if (new_size) {
 137                 unsigned n_pages = new_size >> PAGE_SHIFT;
 138
 139                 __comedi_buf_alloc(dev, s, n_pages);
 140
 141                 if (!async->prealloc_buf) {
 142                         /* allocation failed */
 143                         __comedi_buf_free(dev, s, n_pages);
 144                         return -ENOMEM;
 145                 }
 146                 async->n_buf_pages = n_pages;
 147         }
 148         async->prealloc_bufsz = new_size;
 149
 150         return 0;
 151 }
 152
 153 void comedi_buf_reset(struct comedi_async *async)
 154 {
 155         async->buf_write_alloc_count = 0;
 156         async->buf_write_count = 0;
 157         async->buf_read_alloc_count = 0;
 158         async->buf_read_count = 0;
 159
 160         async->buf_write_ptr = 0;
 161         async->buf_read_ptr = 0;
 162
 163         async->cur_chan = 0;
 164         async->scan_progress = 0;
 165         async->munge_chan = 0;
 166         async->munge_count = 0;
 167         async->munge_ptr = 0;
 168
 169         async->events = 0;
 170 }
 171
 172 static unsigned int comedi_buf_write_n_available(struct comedi_async *async)
 173 {
 174         unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
 175
 176         return free_end - async->buf_write_alloc_count;
 177 }
 178
 179 static unsigned int __comedi_buf_write_alloc(struct comedi_async *async,
 180                                              unsigned int nbytes,
 181                                              int strict)
 182 {
 183         unsigned int available = comedi_buf_write_n_available(async);
 184
 185         if (nbytes > available)
 186                 nbytes = strict ? 0 : available;
 187
 188         async->buf_write_alloc_count += nbytes;
 189
 190         /*
 191          * ensure the async buffer 'counts' are read and updated
 192          * before we write data to the write-alloc'ed buffer space
 193          */
 194         smp_mb();
 195
 196         return nbytes;
 197 }
 198
 199 /* allocates chunk for the writer from free buffer space */
 200 unsigned int comedi_buf_write_alloc(struct comedi_async *async,
 201                                     unsigned int nbytes)
 202 {
 203         return __comedi_buf_write_alloc(async, nbytes, 0);
 204 }
 205 EXPORT_SYMBOL_GPL(comedi_buf_write_alloc);
 206
 207 /*
 208  * munging is applied to data by core as it passes between user
 209  * and kernel space
 210  */
 211 static unsigned int comedi_buf_munge(struct comedi_async *async,
 212                                      unsigned int num_bytes)
 213 {
 214         struct comedi_subdevice *s = async->subdevice;
 215         unsigned int count = 0;
 216         const unsigned num_sample_bytes = bytes_per_sample(s);
 217
 218         if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {
 219                 async->munge_count += num_bytes;
 220                 count = num_bytes;
 221         } else {
 222                 /* don't munge partial samples */
 223                 num_bytes -= num_bytes % num_sample_bytes;
 224                 while (count < num_bytes) {
 225                         int block_size = num_bytes - count;
 226                         unsigned int buf_end;
 227
 228                         buf_end = async->prealloc_bufsz - async->munge_ptr;
 229                         if (block_size > buf_end)
 230                                 block_size = buf_end;
 231
 232                         s->munge(s->device, s,
 233                                  async->prealloc_buf + async->munge_ptr,
 234                                  block_size, async->munge_chan);
 235
 236                         /*
 237                          * ensure data is munged in buffer before the
 238                          * async buffer munge_count is incremented
 239                          */
 240                         smp_wmb();
 241
 242                         async->munge_chan += block_size / num_sample_bytes;
 243                         async->munge_chan %= async->cmd.chanlist_len;
 244                         async->munge_count += block_size;
 245                         async->munge_ptr += block_size;
 246                         async->munge_ptr %= async->prealloc_bufsz;
 247                         count += block_size;
 248                 }
 249         }
 250
 251         return count;
 252 }
 253
 254 unsigned int comedi_buf_write_n_allocated(struct comedi_async *async)
 255 {
 256         return async->buf_write_alloc_count - async->buf_write_count;
 257 }
 258
 259 /* transfers a chunk from writer to filled buffer space */
 260 unsigned int comedi_buf_write_free(struct comedi_async *async,
 261                                    unsigned int nbytes)
 262 {
 263         unsigned int allocated = comedi_buf_write_n_allocated(async);
 264
 265         if (nbytes > allocated)
 266                 nbytes = allocated;
 267
 268         async->buf_write_count += nbytes;
 269         async->buf_write_ptr += nbytes;
 270         comedi_buf_munge(async, async->buf_write_count - async->munge_count);
 271         if (async->buf_write_ptr >= async->prealloc_bufsz)
 272                 async->buf_write_ptr %= async->prealloc_bufsz;
 273
 274         return nbytes;
 275 }
 276 EXPORT_SYMBOL_GPL(comedi_buf_write_free);
 277
 278 unsigned int comedi_buf_read_n_available(struct comedi_async *async)
 279 {
 280         unsigned num_bytes;
 281
 282         if (!async)
 283                 return 0;
 284
 285         num_bytes = async->munge_count - async->buf_read_count;
 286
 287         /*
 288          * ensure the async buffer 'counts' are read before we
 289          * attempt to read data from the buffer
 290          */
 291         smp_rmb();
 292
 293         return num_bytes;
 294 }
 295 EXPORT_SYMBOL_GPL(comedi_buf_read_n_available);
 296
 297 /* allocates a chunk for the reader from filled (and munged) buffer space */
 298 unsigned int comedi_buf_read_alloc(struct comedi_async *async,
 299                                    unsigned int nbytes)
 300 {
 301         unsigned int available;
 302
 303         available = async->munge_count - async->buf_read_alloc_count;
 304         if (nbytes > available)
 305                 nbytes = available;
 306
 307         async->buf_read_alloc_count += nbytes;
 308
 309         /*
 310          * ensure the async buffer 'counts' are read before we
 311          * attempt to read data from the read-alloc'ed buffer space
 312          */
 313         smp_rmb();
 314
 315         return nbytes;
 316 }
 317 EXPORT_SYMBOL_GPL(comedi_buf_read_alloc);
 318
 319 static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async)
 320 {
 321         return async->buf_read_alloc_count - async->buf_read_count;
 322 }
 323
 324 /* transfers control of a chunk from reader to free buffer space */
 325 unsigned int comedi_buf_read_free(struct comedi_async *async,
 326                                   unsigned int nbytes)
 327 {
 328         unsigned int allocated;
 329
 330         /*
 331          * ensure data has been read out of buffer before
 332          * the async read count is incremented
 333          */
 334         smp_mb();
 335
 336         allocated = comedi_buf_read_n_allocated(async);
 337         if (nbytes > allocated)
 338                 nbytes = allocated;
 339
 340         async->buf_read_count += nbytes;
 341         async->buf_read_ptr += nbytes;
 342         async->buf_read_ptr %= async->prealloc_bufsz;
 343         return nbytes;
 344 }
 345 EXPORT_SYMBOL_GPL(comedi_buf_read_free);
 346
 347 int comedi_buf_put(struct comedi_async *async, unsigned short x)
 348 {
 349         unsigned int n = __comedi_buf_write_alloc(async, sizeof(short), 1);
 350
 351         if (n < sizeof(short)) {
 352                 async->events |= COMEDI_CB_ERROR;
 353                 return 0;
 354         }
 355         *(unsigned short *)(async->prealloc_buf + async->buf_write_ptr) = x;
 356         comedi_buf_write_free(async, sizeof(short));
 357         return 1;
 358 }
 359 EXPORT_SYMBOL_GPL(comedi_buf_put);
 360
 361 int comedi_buf_get(struct comedi_async *async, unsigned short *x)
 362 {
 363         unsigned int n = comedi_buf_read_n_available(async);
 364
 365         if (n < sizeof(short))
 366                 return 0;
 367         comedi_buf_read_alloc(async, sizeof(short));
 368         *x = *(unsigned short *)(async->prealloc_buf + async->buf_read_ptr);
 369         comedi_buf_read_free(async, sizeof(short));
 370         return 1;
 371 }
 372 EXPORT_SYMBOL_GPL(comedi_buf_get);
 373
 374 void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
 375                           const void *data, unsigned int num_bytes)
 376 {
 377         unsigned int write_ptr = async->buf_write_ptr + offset;
 378
 379         if (write_ptr >= async->prealloc_bufsz)
 380                 write_ptr %= async->prealloc_bufsz;
 381
 382         while (num_bytes) {
 383                 unsigned int block_size;
 384
 385                 if (write_ptr + num_bytes > async->prealloc_bufsz)
 386                         block_size = async->prealloc_bufsz - write_ptr;
 387                 else
 388                         block_size = num_bytes;
 389
 390                 memcpy(async->prealloc_buf + write_ptr, data, block_size);
 391
 392                 data += block_size;
 393                 num_bytes -= block_size;
 394
 395                 write_ptr = 0;
 396         }
 397 }
 398 EXPORT_SYMBOL_GPL(comedi_buf_memcpy_to);
 399
 400 void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
 401                             void *dest, unsigned int nbytes)
 402 {
 403         void *src;
 404         unsigned int read_ptr = async->buf_read_ptr + offset;
 405
 406         if (read_ptr >= async->prealloc_bufsz)
 407                 read_ptr %= async->prealloc_bufsz;
 408
 409         while (nbytes) {
 410                 unsigned int block_size;
 411
 412                 src = async->prealloc_buf + read_ptr;
 413
 414                 if (nbytes >= async->prealloc_bufsz - read_ptr)
 415                         block_size = async->prealloc_bufsz - read_ptr;
 416                 else
 417                         block_size = nbytes;
 418
 419                 memcpy(dest, src, block_size);
 420                 nbytes -= block_size;
 421                 dest += block_size;
 422                 read_ptr = 0;
 423         }
 424 }
 425 EXPORT_SYMBOL_GPL(comedi_buf_memcpy_from);