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1// SPDX-License-Identifier: GPL-2.0+2/*3 * comedi_buf.c4 *5 * COMEDI - Linux Control and Measurement Device Interface6 * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>7 * Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net>8 */9 10#include <linux/vmalloc.h>11#include <linux/slab.h>12#include <linux/comedi/comedidev.h>13#include "comedi_internal.h"14 15#ifdef PAGE_KERNEL_NOCACHE16#define COMEDI_PAGE_PROTECTION PAGE_KERNEL_NOCACHE17#else18#define COMEDI_PAGE_PROTECTION PAGE_KERNEL19#endif20 21static void comedi_buf_map_kref_release(struct kref *kref)22{23 struct comedi_buf_map *bm =24 container_of(kref, struct comedi_buf_map, refcount);25 struct comedi_buf_page *buf;26 unsigned int i;27 28 if (bm->page_list) {29 if (bm->dma_dir != DMA_NONE) {30 /*31 * DMA buffer was allocated as a single block.32 * Address is in page_list[0].33 */34 buf = &bm->page_list[0];35 dma_free_coherent(bm->dma_hw_dev,36 PAGE_SIZE * bm->n_pages,37 buf->virt_addr, buf->dma_addr);38 } else {39 for (i = 0; i < bm->n_pages; i++) {40 buf = &bm->page_list[i];41 ClearPageReserved(virt_to_page(buf->virt_addr));42 free_page((unsigned long)buf->virt_addr);43 }44 }45 vfree(bm->page_list);46 }47 if (bm->dma_dir != DMA_NONE)48 put_device(bm->dma_hw_dev);49 kfree(bm);50}51 52static void __comedi_buf_free(struct comedi_device *dev,53 struct comedi_subdevice *s)54{55 struct comedi_async *async = s->async;56 struct comedi_buf_map *bm;57 unsigned long flags;58 59 if (async->prealloc_buf) {60 if (s->async_dma_dir == DMA_NONE)61 vunmap(async->prealloc_buf);62 async->prealloc_buf = NULL;63 async->prealloc_bufsz = 0;64 }65 66 spin_lock_irqsave(&s->spin_lock, flags);67 bm = async->buf_map;68 async->buf_map = NULL;69 spin_unlock_irqrestore(&s->spin_lock, flags);70 comedi_buf_map_put(bm);71}72 73static struct comedi_buf_map *74comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir,75 unsigned int n_pages)76{77 struct comedi_buf_map *bm;78 struct comedi_buf_page *buf;79 unsigned int i;80 81 bm = kzalloc(sizeof(*bm), GFP_KERNEL);82 if (!bm)83 return NULL;84 85 kref_init(&bm->refcount);86 bm->dma_dir = dma_dir;87 if (bm->dma_dir != DMA_NONE) {88 /* Need ref to hardware device to free buffer later. */89 bm->dma_hw_dev = get_device(dev->hw_dev);90 }91 92 bm->page_list = vzalloc(sizeof(*buf) * n_pages);93 if (!bm->page_list)94 goto err;95 96 if (bm->dma_dir != DMA_NONE) {97 void *virt_addr;98 dma_addr_t dma_addr;99 100 /*101 * Currently, the DMA buffer needs to be allocated as a102 * single block so that it can be mmap()'ed.103 */104 virt_addr = dma_alloc_coherent(bm->dma_hw_dev,105 PAGE_SIZE * n_pages, &dma_addr,106 GFP_KERNEL);107 if (!virt_addr)108 goto err;109 110 for (i = 0; i < n_pages; i++) {111 buf = &bm->page_list[i];112 buf->virt_addr = virt_addr + (i << PAGE_SHIFT);113 buf->dma_addr = dma_addr + (i << PAGE_SHIFT);114 }115 116 bm->n_pages = i;117 } else {118 for (i = 0; i < n_pages; i++) {119 buf = &bm->page_list[i];120 buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);121 if (!buf->virt_addr)122 break;123 124 SetPageReserved(virt_to_page(buf->virt_addr));125 }126 127 bm->n_pages = i;128 if (i < n_pages)129 goto err;130 }131 132 return bm;133 134err:135 comedi_buf_map_put(bm);136 return NULL;137}138 139static void __comedi_buf_alloc(struct comedi_device *dev,140 struct comedi_subdevice *s,141 unsigned int n_pages)142{143 struct comedi_async *async = s->async;144 struct page **pages = NULL;145 struct comedi_buf_map *bm;146 struct comedi_buf_page *buf;147 unsigned long flags;148 unsigned int i;149 150 if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {151 dev_err(dev->class_dev,152 "dma buffer allocation not supported\n");153 return;154 }155 156 bm = comedi_buf_map_alloc(dev, s->async_dma_dir, n_pages);157 if (!bm)158 return;159 160 spin_lock_irqsave(&s->spin_lock, flags);161 async->buf_map = bm;162 spin_unlock_irqrestore(&s->spin_lock, flags);163 164 if (bm->dma_dir != DMA_NONE) {165 /*166 * DMA buffer was allocated as a single block.167 * Address is in page_list[0].168 */169 buf = &bm->page_list[0];170 async->prealloc_buf = buf->virt_addr;171 } else {172 pages = vmalloc(sizeof(struct page *) * n_pages);173 if (!pages)174 return;175 176 for (i = 0; i < n_pages; i++) {177 buf = &bm->page_list[i];178 pages[i] = virt_to_page(buf->virt_addr);179 }180 181 /* vmap the pages to prealloc_buf */182 async->prealloc_buf = vmap(pages, n_pages, VM_MAP,183 COMEDI_PAGE_PROTECTION);184 185 vfree(pages);186 }187}188 189void comedi_buf_map_get(struct comedi_buf_map *bm)190{191 if (bm)192 kref_get(&bm->refcount);193}194 195int comedi_buf_map_put(struct comedi_buf_map *bm)196{197 if (bm)198 return kref_put(&bm->refcount, comedi_buf_map_kref_release);199 return 1;200}201 202/* helper for "access" vm operation */203int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset,204 void *buf, int len, int write)205{206 unsigned int pgoff = offset_in_page(offset);207 unsigned long pg = offset >> PAGE_SHIFT;208 int done = 0;209 210 while (done < len && pg < bm->n_pages) {211 int l = min_t(int, len - done, PAGE_SIZE - pgoff);212 void *b = bm->page_list[pg].virt_addr + pgoff;213 214 if (write)215 memcpy(b, buf, l);216 else217 memcpy(buf, b, l);218 buf += l;219 done += l;220 pg++;221 pgoff = 0;222 }223 return done;224}225 226/* returns s->async->buf_map and increments its kref refcount */227struct comedi_buf_map *228comedi_buf_map_from_subdev_get(struct comedi_subdevice *s)229{230 struct comedi_async *async = s->async;231 struct comedi_buf_map *bm = NULL;232 unsigned long flags;233 234 if (!async)235 return NULL;236 237 spin_lock_irqsave(&s->spin_lock, flags);238 bm = async->buf_map;239 /* only want it if buffer pages allocated */240 if (bm && bm->n_pages)241 comedi_buf_map_get(bm);242 else243 bm = NULL;244 spin_unlock_irqrestore(&s->spin_lock, flags);245 246 return bm;247}248 249bool comedi_buf_is_mmapped(struct comedi_subdevice *s)250{251 struct comedi_buf_map *bm = s->async->buf_map;252 253 return bm && (kref_read(&bm->refcount) > 1);254}255 256int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,257 unsigned long new_size)258{259 struct comedi_async *async = s->async;260 261 lockdep_assert_held(&dev->mutex);262 263 /* Round up new_size to multiple of PAGE_SIZE */264 new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;265 266 /* if no change is required, do nothing */267 if (async->prealloc_buf && async->prealloc_bufsz == new_size)268 return 0;269 270 /* deallocate old buffer */271 __comedi_buf_free(dev, s);272 273 /* allocate new buffer */274 if (new_size) {275 unsigned int n_pages = new_size >> PAGE_SHIFT;276 277 __comedi_buf_alloc(dev, s, n_pages);278 279 if (!async->prealloc_buf) {280 /* allocation failed */281 __comedi_buf_free(dev, s);282 return -ENOMEM;283 }284 }285 async->prealloc_bufsz = new_size;286 287 return 0;288}289 290void comedi_buf_reset(struct comedi_subdevice *s)291{292 struct comedi_async *async = s->async;293 294 async->buf_write_alloc_count = 0;295 async->buf_write_count = 0;296 async->buf_read_alloc_count = 0;297 async->buf_read_count = 0;298 299 async->buf_write_ptr = 0;300 async->buf_read_ptr = 0;301 302 async->cur_chan = 0;303 async->scans_done = 0;304 async->scan_progress = 0;305 async->munge_chan = 0;306 async->munge_count = 0;307 async->munge_ptr = 0;308 309 async->events = 0;310}311 312static unsigned int comedi_buf_write_n_unalloc(struct comedi_subdevice *s)313{314 struct comedi_async *async = s->async;315 unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;316 317 return free_end - async->buf_write_alloc_count;318}319 320unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s)321{322 struct comedi_async *async = s->async;323 unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;324 325 return free_end - async->buf_write_count;326}327 328/**329 * comedi_buf_write_alloc() - Reserve buffer space for writing330 * @s: COMEDI subdevice.331 * @nbytes: Maximum space to reserve in bytes.332 *333 * Reserve up to @nbytes bytes of space to be written in the COMEDI acquisition334 * data buffer associated with the subdevice. The amount reserved is limited335 * by the space available.336 *337 * Return: The amount of space reserved in bytes.338 */339unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s,340 unsigned int nbytes)341{342 struct comedi_async *async = s->async;343 unsigned int unalloc = comedi_buf_write_n_unalloc(s);344 345 if (nbytes > unalloc)346 nbytes = unalloc;347 348 async->buf_write_alloc_count += nbytes;349 350 /*351 * ensure the async buffer 'counts' are read and updated352 * before we write data to the write-alloc'ed buffer space353 */354 smp_mb();355 356 return nbytes;357}358EXPORT_SYMBOL_GPL(comedi_buf_write_alloc);359 360/*361 * munging is applied to data by core as it passes between user362 * and kernel space363 */364static unsigned int comedi_buf_munge(struct comedi_subdevice *s,365 unsigned int num_bytes)366{367 struct comedi_async *async = s->async;368 unsigned int count = 0;369 const unsigned int num_sample_bytes = comedi_bytes_per_sample(s);370 371 if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {372 async->munge_count += num_bytes;373 return num_bytes;374 }375 376 /* don't munge partial samples */377 num_bytes -= num_bytes % num_sample_bytes;378 while (count < num_bytes) {379 int block_size = num_bytes - count;380 unsigned int buf_end;381 382 buf_end = async->prealloc_bufsz - async->munge_ptr;383 if (block_size > buf_end)384 block_size = buf_end;385 386 s->munge(s->device, s,387 async->prealloc_buf + async->munge_ptr,388 block_size, async->munge_chan);389 390 /*391 * ensure data is munged in buffer before the392 * async buffer munge_count is incremented393 */394 smp_wmb();395 396 async->munge_chan += block_size / num_sample_bytes;397 async->munge_chan %= async->cmd.chanlist_len;398 async->munge_count += block_size;399 async->munge_ptr += block_size;400 async->munge_ptr %= async->prealloc_bufsz;401 count += block_size;402 }403 404 return count;405}406 407unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s)408{409 struct comedi_async *async = s->async;410 411 return async->buf_write_alloc_count - async->buf_write_count;412}413 414/**415 * comedi_buf_write_free() - Free buffer space after it is written416 * @s: COMEDI subdevice.417 * @nbytes: Maximum space to free in bytes.418 *419 * Free up to @nbytes bytes of space previously reserved for writing in the420 * COMEDI acquisition data buffer associated with the subdevice. The amount of421 * space freed is limited to the amount that was reserved. The freed space is422 * assumed to have been filled with sample data by the writer.423 *424 * If the samples in the freed space need to be "munged", do so here. The425 * freed space becomes available for allocation by the reader.426 *427 * Return: The amount of space freed in bytes.428 */429unsigned int comedi_buf_write_free(struct comedi_subdevice *s,430 unsigned int nbytes)431{432 struct comedi_async *async = s->async;433 unsigned int allocated = comedi_buf_write_n_allocated(s);434 435 if (nbytes > allocated)436 nbytes = allocated;437 438 async->buf_write_count += nbytes;439 async->buf_write_ptr += nbytes;440 comedi_buf_munge(s, async->buf_write_count - async->munge_count);441 if (async->buf_write_ptr >= async->prealloc_bufsz)442 async->buf_write_ptr %= async->prealloc_bufsz;443 444 return nbytes;445}446EXPORT_SYMBOL_GPL(comedi_buf_write_free);447 448/**449 * comedi_buf_read_n_available() - Determine amount of readable buffer space450 * @s: COMEDI subdevice.451 *452 * Determine the amount of readable buffer space in the COMEDI acquisition data453 * buffer associated with the subdevice. The readable buffer space is that454 * which has been freed by the writer and "munged" to the sample data format455 * expected by COMEDI if necessary.456 *457 * Return: The amount of readable buffer space.458 */459unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s)460{461 struct comedi_async *async = s->async;462 unsigned int num_bytes;463 464 if (!async)465 return 0;466 467 num_bytes = async->munge_count - async->buf_read_count;468 469 /*470 * ensure the async buffer 'counts' are read before we471 * attempt to read data from the buffer472 */473 smp_rmb();474 475 return num_bytes;476}477EXPORT_SYMBOL_GPL(comedi_buf_read_n_available);478 479/**480 * comedi_buf_read_alloc() - Reserve buffer space for reading481 * @s: COMEDI subdevice.482 * @nbytes: Maximum space to reserve in bytes.483 *484 * Reserve up to @nbytes bytes of previously written and "munged" buffer space485 * for reading in the COMEDI acquisition data buffer associated with the486 * subdevice. The amount reserved is limited to the space available. The487 * reader can read from the reserved space and then free it. A reader is also488 * allowed to read from the space before reserving it as long as it determines489 * the amount of readable data available, but the space needs to be marked as490 * reserved before it can be freed.491 *492 * Return: The amount of space reserved in bytes.493 */494unsigned int comedi_buf_read_alloc(struct comedi_subdevice *s,495 unsigned int nbytes)496{497 struct comedi_async *async = s->async;498 unsigned int available;499 500 available = async->munge_count - async->buf_read_alloc_count;501 if (nbytes > available)502 nbytes = available;503 504 async->buf_read_alloc_count += nbytes;505 506 /*507 * ensure the async buffer 'counts' are read before we508 * attempt to read data from the read-alloc'ed buffer space509 */510 smp_rmb();511 512 return nbytes;513}514EXPORT_SYMBOL_GPL(comedi_buf_read_alloc);515 516static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async)517{518 return async->buf_read_alloc_count - async->buf_read_count;519}520 521/**522 * comedi_buf_read_free() - Free buffer space after it has been read523 * @s: COMEDI subdevice.524 * @nbytes: Maximum space to free in bytes.525 *526 * Free up to @nbytes bytes of buffer space previously reserved for reading in527 * the COMEDI acquisition data buffer associated with the subdevice. The528 * amount of space freed is limited to the amount that was reserved.529 *530 * The freed space becomes available for allocation by the writer.531 *532 * Return: The amount of space freed in bytes.533 */534unsigned int comedi_buf_read_free(struct comedi_subdevice *s,535 unsigned int nbytes)536{537 struct comedi_async *async = s->async;538 unsigned int allocated;539 540 /*541 * ensure data has been read out of buffer before542 * the async read count is incremented543 */544 smp_mb();545 546 allocated = comedi_buf_read_n_allocated(async);547 if (nbytes > allocated)548 nbytes = allocated;549 550 async->buf_read_count += nbytes;551 async->buf_read_ptr += nbytes;552 async->buf_read_ptr %= async->prealloc_bufsz;553 return nbytes;554}555EXPORT_SYMBOL_GPL(comedi_buf_read_free);556 557static void comedi_buf_memcpy_to(struct comedi_subdevice *s,558 const void *data, unsigned int num_bytes)559{560 struct comedi_async *async = s->async;561 unsigned int write_ptr = async->buf_write_ptr;562 563 while (num_bytes) {564 unsigned int block_size;565 566 if (write_ptr + num_bytes > async->prealloc_bufsz)567 block_size = async->prealloc_bufsz - write_ptr;568 else569 block_size = num_bytes;570 571 memcpy(async->prealloc_buf + write_ptr, data, block_size);572 573 data += block_size;574 num_bytes -= block_size;575 576 write_ptr = 0;577 }578}579 580static void comedi_buf_memcpy_from(struct comedi_subdevice *s,581 void *dest, unsigned int nbytes)582{583 void *src;584 struct comedi_async *async = s->async;585 unsigned int read_ptr = async->buf_read_ptr;586 587 while (nbytes) {588 unsigned int block_size;589 590 src = async->prealloc_buf + read_ptr;591 592 if (nbytes >= async->prealloc_bufsz - read_ptr)593 block_size = async->prealloc_bufsz - read_ptr;594 else595 block_size = nbytes;596 597 memcpy(dest, src, block_size);598 nbytes -= block_size;599 dest += block_size;600 read_ptr = 0;601 }602}603 604/**605 * comedi_buf_write_samples() - Write sample data to COMEDI buffer606 * @s: COMEDI subdevice.607 * @data: Pointer to source samples.608 * @nsamples: Number of samples to write.609 *610 * Write up to @nsamples samples to the COMEDI acquisition data buffer611 * associated with the subdevice, mark it as written and update the612 * acquisition scan progress. If there is not enough room for the specified613 * number of samples, the number of samples written is limited to the number614 * that will fit and the %COMEDI_CB_OVERFLOW event flag is set to cause the615 * acquisition to terminate with an overrun error. Set the %COMEDI_CB_BLOCK616 * event flag if any samples are written to cause waiting tasks to be woken617 * when the event flags are processed.618 *619 * Return: The amount of data written in bytes.620 */621unsigned int comedi_buf_write_samples(struct comedi_subdevice *s,622 const void *data, unsigned int nsamples)623{624 unsigned int max_samples;625 unsigned int nbytes;626 627 /*628 * Make sure there is enough room in the buffer for all the samples.629 * If not, clamp the nsamples to the number that will fit, flag the630 * buffer overrun and add the samples that fit.631 */632 max_samples = comedi_bytes_to_samples(s, comedi_buf_write_n_unalloc(s));633 if (nsamples > max_samples) {634 dev_warn(s->device->class_dev, "buffer overrun\n");635 s->async->events |= COMEDI_CB_OVERFLOW;636 nsamples = max_samples;637 }638 639 if (nsamples == 0)640 return 0;641 642 nbytes = comedi_buf_write_alloc(s,643 comedi_samples_to_bytes(s, nsamples));644 comedi_buf_memcpy_to(s, data, nbytes);645 comedi_buf_write_free(s, nbytes);646 comedi_inc_scan_progress(s, nbytes);647 s->async->events |= COMEDI_CB_BLOCK;648 649 return nbytes;650}651EXPORT_SYMBOL_GPL(comedi_buf_write_samples);652 653/**654 * comedi_buf_read_samples() - Read sample data from COMEDI buffer655 * @s: COMEDI subdevice.656 * @data: Pointer to destination.657 * @nsamples: Maximum number of samples to read.658 *659 * Read up to @nsamples samples from the COMEDI acquisition data buffer660 * associated with the subdevice, mark it as read and update the acquisition661 * scan progress. Limit the number of samples read to the number available.662 * Set the %COMEDI_CB_BLOCK event flag if any samples are read to cause waiting663 * tasks to be woken when the event flags are processed.664 *665 * Return: The amount of data read in bytes.666 */667unsigned int comedi_buf_read_samples(struct comedi_subdevice *s,668 void *data, unsigned int nsamples)669{670 unsigned int max_samples;671 unsigned int nbytes;672 673 /* clamp nsamples to the number of full samples available */674 max_samples = comedi_bytes_to_samples(s,675 comedi_buf_read_n_available(s));676 if (nsamples > max_samples)677 nsamples = max_samples;678 679 if (nsamples == 0)680 return 0;681 682 nbytes = comedi_buf_read_alloc(s,683 comedi_samples_to_bytes(s, nsamples));684 comedi_buf_memcpy_from(s, data, nbytes);685 comedi_buf_read_free(s, nbytes);686 comedi_inc_scan_progress(s, nbytes);687 s->async->events |= COMEDI_CB_BLOCK;688 689 return nbytes;690}691EXPORT_SYMBOL_GPL(comedi_buf_read_samples);692