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692 lines
18 KiB
692 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* comedi_buf.c |
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* |
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* COMEDI - Linux Control and Measurement Device Interface |
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* Copyright (C) 1997-2000 David A. Schleef <[email protected]> |
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* Copyright (C) 2002 Frank Mori Hess <[email protected]> |
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*/ |
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|
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#include <linux/vmalloc.h> |
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#include <linux/slab.h> |
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|
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#include "comedidev.h" |
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#include "comedi_internal.h" |
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#ifdef PAGE_KERNEL_NOCACHE |
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#define COMEDI_PAGE_PROTECTION PAGE_KERNEL_NOCACHE |
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#else |
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#define COMEDI_PAGE_PROTECTION PAGE_KERNEL |
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#endif |
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static void comedi_buf_map_kref_release(struct kref *kref) |
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{ |
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struct comedi_buf_map *bm = |
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container_of(kref, struct comedi_buf_map, refcount); |
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struct comedi_buf_page *buf; |
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unsigned int i; |
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if (bm->page_list) { |
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if (bm->dma_dir != DMA_NONE) { |
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/* |
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* DMA buffer was allocated as a single block. |
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* Address is in page_list[0]. |
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*/ |
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buf = &bm->page_list[0]; |
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dma_free_coherent(bm->dma_hw_dev, |
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PAGE_SIZE * bm->n_pages, |
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buf->virt_addr, buf->dma_addr); |
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} else { |
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for (i = 0; i < bm->n_pages; i++) { |
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buf = &bm->page_list[i]; |
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ClearPageReserved(virt_to_page(buf->virt_addr)); |
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free_page((unsigned long)buf->virt_addr); |
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} |
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} |
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vfree(bm->page_list); |
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} |
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if (bm->dma_dir != DMA_NONE) |
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put_device(bm->dma_hw_dev); |
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kfree(bm); |
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} |
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static void __comedi_buf_free(struct comedi_device *dev, |
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struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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struct comedi_buf_map *bm; |
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unsigned long flags; |
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if (async->prealloc_buf) { |
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if (s->async_dma_dir == DMA_NONE) |
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vunmap(async->prealloc_buf); |
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async->prealloc_buf = NULL; |
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async->prealloc_bufsz = 0; |
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} |
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spin_lock_irqsave(&s->spin_lock, flags); |
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bm = async->buf_map; |
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async->buf_map = NULL; |
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spin_unlock_irqrestore(&s->spin_lock, flags); |
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comedi_buf_map_put(bm); |
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} |
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static struct comedi_buf_map * |
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comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir, |
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unsigned int n_pages) |
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{ |
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struct comedi_buf_map *bm; |
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struct comedi_buf_page *buf; |
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unsigned int i; |
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bm = kzalloc(sizeof(*bm), GFP_KERNEL); |
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if (!bm) |
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return NULL; |
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kref_init(&bm->refcount); |
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bm->dma_dir = dma_dir; |
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if (bm->dma_dir != DMA_NONE) { |
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/* Need ref to hardware device to free buffer later. */ |
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bm->dma_hw_dev = get_device(dev->hw_dev); |
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} |
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bm->page_list = vzalloc(sizeof(*buf) * n_pages); |
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if (!bm->page_list) |
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goto err; |
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if (bm->dma_dir != DMA_NONE) { |
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void *virt_addr; |
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dma_addr_t dma_addr; |
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/* |
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* Currently, the DMA buffer needs to be allocated as a |
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* single block so that it can be mmap()'ed. |
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*/ |
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virt_addr = dma_alloc_coherent(bm->dma_hw_dev, |
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PAGE_SIZE * n_pages, &dma_addr, |
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GFP_KERNEL); |
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if (!virt_addr) |
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goto err; |
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for (i = 0; i < n_pages; i++) { |
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buf = &bm->page_list[i]; |
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buf->virt_addr = virt_addr + (i << PAGE_SHIFT); |
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buf->dma_addr = dma_addr + (i << PAGE_SHIFT); |
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} |
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bm->n_pages = i; |
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} else { |
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for (i = 0; i < n_pages; i++) { |
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buf = &bm->page_list[i]; |
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buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL); |
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if (!buf->virt_addr) |
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break; |
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SetPageReserved(virt_to_page(buf->virt_addr)); |
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} |
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bm->n_pages = i; |
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if (i < n_pages) |
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goto err; |
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} |
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return bm; |
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err: |
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comedi_buf_map_put(bm); |
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return NULL; |
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} |
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static void __comedi_buf_alloc(struct comedi_device *dev, |
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struct comedi_subdevice *s, |
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unsigned int n_pages) |
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{ |
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struct comedi_async *async = s->async; |
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struct page **pages = NULL; |
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struct comedi_buf_map *bm; |
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struct comedi_buf_page *buf; |
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unsigned long flags; |
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unsigned int i; |
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if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) { |
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dev_err(dev->class_dev, |
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"dma buffer allocation not supported\n"); |
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return; |
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} |
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bm = comedi_buf_map_alloc(dev, s->async_dma_dir, n_pages); |
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if (!bm) |
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return; |
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spin_lock_irqsave(&s->spin_lock, flags); |
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async->buf_map = bm; |
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spin_unlock_irqrestore(&s->spin_lock, flags); |
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if (bm->dma_dir != DMA_NONE) { |
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/* |
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* DMA buffer was allocated as a single block. |
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* Address is in page_list[0]. |
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*/ |
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buf = &bm->page_list[0]; |
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async->prealloc_buf = buf->virt_addr; |
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} else { |
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pages = vmalloc(sizeof(struct page *) * n_pages); |
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if (!pages) |
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return; |
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for (i = 0; i < n_pages; i++) { |
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buf = &bm->page_list[i]; |
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pages[i] = virt_to_page(buf->virt_addr); |
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} |
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/* vmap the pages to prealloc_buf */ |
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async->prealloc_buf = vmap(pages, n_pages, VM_MAP, |
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COMEDI_PAGE_PROTECTION); |
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vfree(pages); |
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} |
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} |
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void comedi_buf_map_get(struct comedi_buf_map *bm) |
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{ |
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if (bm) |
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kref_get(&bm->refcount); |
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} |
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int comedi_buf_map_put(struct comedi_buf_map *bm) |
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{ |
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if (bm) |
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return kref_put(&bm->refcount, comedi_buf_map_kref_release); |
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return 1; |
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} |
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/* helper for "access" vm operation */ |
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int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset, |
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void *buf, int len, int write) |
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{ |
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unsigned int pgoff = offset_in_page(offset); |
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unsigned long pg = offset >> PAGE_SHIFT; |
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int done = 0; |
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while (done < len && pg < bm->n_pages) { |
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int l = min_t(int, len - done, PAGE_SIZE - pgoff); |
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void *b = bm->page_list[pg].virt_addr + pgoff; |
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if (write) |
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memcpy(b, buf, l); |
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else |
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memcpy(buf, b, l); |
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buf += l; |
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done += l; |
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pg++; |
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pgoff = 0; |
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} |
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return done; |
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} |
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/* returns s->async->buf_map and increments its kref refcount */ |
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struct comedi_buf_map * |
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comedi_buf_map_from_subdev_get(struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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struct comedi_buf_map *bm = NULL; |
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unsigned long flags; |
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if (!async) |
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return NULL; |
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spin_lock_irqsave(&s->spin_lock, flags); |
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bm = async->buf_map; |
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/* only want it if buffer pages allocated */ |
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if (bm && bm->n_pages) |
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comedi_buf_map_get(bm); |
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else |
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bm = NULL; |
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spin_unlock_irqrestore(&s->spin_lock, flags); |
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return bm; |
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} |
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bool comedi_buf_is_mmapped(struct comedi_subdevice *s) |
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{ |
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struct comedi_buf_map *bm = s->async->buf_map; |
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return bm && (kref_read(&bm->refcount) > 1); |
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} |
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int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s, |
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unsigned long new_size) |
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{ |
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struct comedi_async *async = s->async; |
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lockdep_assert_held(&dev->mutex); |
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/* Round up new_size to multiple of PAGE_SIZE */ |
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new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK; |
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/* if no change is required, do nothing */ |
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if (async->prealloc_buf && async->prealloc_bufsz == new_size) |
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return 0; |
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/* deallocate old buffer */ |
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__comedi_buf_free(dev, s); |
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/* allocate new buffer */ |
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if (new_size) { |
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unsigned int n_pages = new_size >> PAGE_SHIFT; |
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__comedi_buf_alloc(dev, s, n_pages); |
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if (!async->prealloc_buf) { |
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/* allocation failed */ |
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__comedi_buf_free(dev, s); |
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return -ENOMEM; |
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} |
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} |
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async->prealloc_bufsz = new_size; |
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return 0; |
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} |
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void comedi_buf_reset(struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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async->buf_write_alloc_count = 0; |
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async->buf_write_count = 0; |
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async->buf_read_alloc_count = 0; |
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async->buf_read_count = 0; |
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async->buf_write_ptr = 0; |
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async->buf_read_ptr = 0; |
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async->cur_chan = 0; |
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async->scans_done = 0; |
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async->scan_progress = 0; |
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async->munge_chan = 0; |
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async->munge_count = 0; |
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async->munge_ptr = 0; |
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async->events = 0; |
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} |
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static unsigned int comedi_buf_write_n_unalloc(struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; |
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return free_end - async->buf_write_alloc_count; |
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} |
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unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; |
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return free_end - async->buf_write_count; |
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} |
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/** |
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* comedi_buf_write_alloc() - Reserve buffer space for writing |
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* @s: COMEDI subdevice. |
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* @nbytes: Maximum space to reserve in bytes. |
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* |
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* Reserve up to @nbytes bytes of space to be written in the COMEDI acquisition |
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* data buffer associated with the subdevice. The amount reserved is limited |
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* by the space available. |
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* |
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* Return: The amount of space reserved in bytes. |
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*/ |
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unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s, |
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unsigned int nbytes) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int unalloc = comedi_buf_write_n_unalloc(s); |
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if (nbytes > unalloc) |
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nbytes = unalloc; |
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async->buf_write_alloc_count += nbytes; |
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/* |
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* ensure the async buffer 'counts' are read and updated |
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* before we write data to the write-alloc'ed buffer space |
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*/ |
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smp_mb(); |
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return nbytes; |
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} |
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EXPORT_SYMBOL_GPL(comedi_buf_write_alloc); |
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/* |
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* munging is applied to data by core as it passes between user |
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* and kernel space |
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*/ |
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static unsigned int comedi_buf_munge(struct comedi_subdevice *s, |
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unsigned int num_bytes) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int count = 0; |
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const unsigned int num_sample_bytes = comedi_bytes_per_sample(s); |
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if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) { |
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async->munge_count += num_bytes; |
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return num_bytes; |
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} |
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/* don't munge partial samples */ |
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num_bytes -= num_bytes % num_sample_bytes; |
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while (count < num_bytes) { |
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int block_size = num_bytes - count; |
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unsigned int buf_end; |
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buf_end = async->prealloc_bufsz - async->munge_ptr; |
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if (block_size > buf_end) |
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block_size = buf_end; |
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s->munge(s->device, s, |
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async->prealloc_buf + async->munge_ptr, |
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block_size, async->munge_chan); |
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/* |
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* ensure data is munged in buffer before the |
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* async buffer munge_count is incremented |
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*/ |
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smp_wmb(); |
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async->munge_chan += block_size / num_sample_bytes; |
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async->munge_chan %= async->cmd.chanlist_len; |
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async->munge_count += block_size; |
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async->munge_ptr += block_size; |
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async->munge_ptr %= async->prealloc_bufsz; |
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count += block_size; |
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} |
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return count; |
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} |
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unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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return async->buf_write_alloc_count - async->buf_write_count; |
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} |
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/** |
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* comedi_buf_write_free() - Free buffer space after it is written |
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* @s: COMEDI subdevice. |
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* @nbytes: Maximum space to free in bytes. |
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* |
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* Free up to @nbytes bytes of space previously reserved for writing in the |
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* COMEDI acquisition data buffer associated with the subdevice. The amount of |
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* space freed is limited to the amount that was reserved. The freed space is |
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* assumed to have been filled with sample data by the writer. |
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* |
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* If the samples in the freed space need to be "munged", do so here. The |
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* freed space becomes available for allocation by the reader. |
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* |
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* Return: The amount of space freed in bytes. |
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*/ |
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unsigned int comedi_buf_write_free(struct comedi_subdevice *s, |
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unsigned int nbytes) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int allocated = comedi_buf_write_n_allocated(s); |
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if (nbytes > allocated) |
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nbytes = allocated; |
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async->buf_write_count += nbytes; |
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async->buf_write_ptr += nbytes; |
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comedi_buf_munge(s, async->buf_write_count - async->munge_count); |
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if (async->buf_write_ptr >= async->prealloc_bufsz) |
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async->buf_write_ptr %= async->prealloc_bufsz; |
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return nbytes; |
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} |
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EXPORT_SYMBOL_GPL(comedi_buf_write_free); |
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/** |
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* comedi_buf_read_n_available() - Determine amount of readable buffer space |
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* @s: COMEDI subdevice. |
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* |
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* Determine the amount of readable buffer space in the COMEDI acquisition data |
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* buffer associated with the subdevice. The readable buffer space is that |
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* which has been freed by the writer and "munged" to the sample data format |
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* expected by COMEDI if necessary. |
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* |
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* Return: The amount of readable buffer space. |
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*/ |
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unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int num_bytes; |
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if (!async) |
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return 0; |
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num_bytes = async->munge_count - async->buf_read_count; |
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/* |
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* ensure the async buffer 'counts' are read before we |
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* attempt to read data from the buffer |
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*/ |
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smp_rmb(); |
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return num_bytes; |
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} |
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EXPORT_SYMBOL_GPL(comedi_buf_read_n_available); |
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/** |
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* comedi_buf_read_alloc() - Reserve buffer space for reading |
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* @s: COMEDI subdevice. |
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* @nbytes: Maximum space to reserve in bytes. |
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* |
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* Reserve up to @nbytes bytes of previously written and "munged" buffer space |
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* for reading in the COMEDI acquisition data buffer associated with the |
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* subdevice. The amount reserved is limited to the space available. The |
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* reader can read from the reserved space and then free it. A reader is also |
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* allowed to read from the space before reserving it as long as it determines |
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* the amount of readable data available, but the space needs to be marked as |
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* reserved before it can be freed. |
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* |
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* Return: The amount of space reserved in bytes. |
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*/ |
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unsigned int comedi_buf_read_alloc(struct comedi_subdevice *s, |
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unsigned int nbytes) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int available; |
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available = async->munge_count - async->buf_read_alloc_count; |
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if (nbytes > available) |
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nbytes = available; |
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async->buf_read_alloc_count += nbytes; |
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/* |
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* ensure the async buffer 'counts' are read before we |
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* attempt to read data from the read-alloc'ed buffer space |
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*/ |
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smp_rmb(); |
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return nbytes; |
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} |
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EXPORT_SYMBOL_GPL(comedi_buf_read_alloc); |
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static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async) |
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{ |
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return async->buf_read_alloc_count - async->buf_read_count; |
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} |
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|
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/** |
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* comedi_buf_read_free() - Free buffer space after it has been read |
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* @s: COMEDI subdevice. |
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* @nbytes: Maximum space to free in bytes. |
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* |
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* Free up to @nbytes bytes of buffer space previously reserved for reading in |
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* the COMEDI acquisition data buffer associated with the subdevice. The |
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* amount of space freed is limited to the amount that was reserved. |
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* |
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* The freed space becomes available for allocation by the writer. |
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* |
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* Return: The amount of space freed in bytes. |
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*/ |
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unsigned int comedi_buf_read_free(struct comedi_subdevice *s, |
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unsigned int nbytes) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int allocated; |
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|
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/* |
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* ensure data has been read out of buffer before |
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* the async read count is incremented |
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*/ |
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smp_mb(); |
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allocated = comedi_buf_read_n_allocated(async); |
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if (nbytes > allocated) |
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nbytes = allocated; |
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async->buf_read_count += nbytes; |
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async->buf_read_ptr += nbytes; |
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async->buf_read_ptr %= async->prealloc_bufsz; |
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return nbytes; |
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} |
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EXPORT_SYMBOL_GPL(comedi_buf_read_free); |
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|
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static void comedi_buf_memcpy_to(struct comedi_subdevice *s, |
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const void *data, unsigned int num_bytes) |
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{ |
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struct comedi_async *async = s->async; |
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unsigned int write_ptr = async->buf_write_ptr; |
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while (num_bytes) { |
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unsigned int block_size; |
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if (write_ptr + num_bytes > async->prealloc_bufsz) |
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block_size = async->prealloc_bufsz - write_ptr; |
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else |
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block_size = num_bytes; |
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memcpy(async->prealloc_buf + write_ptr, data, block_size); |
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data += block_size; |
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num_bytes -= block_size; |
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write_ptr = 0; |
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} |
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} |
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static void comedi_buf_memcpy_from(struct comedi_subdevice *s, |
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void *dest, unsigned int nbytes) |
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{ |
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void *src; |
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struct comedi_async *async = s->async; |
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unsigned int read_ptr = async->buf_read_ptr; |
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while (nbytes) { |
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unsigned int block_size; |
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src = async->prealloc_buf + read_ptr; |
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if (nbytes >= async->prealloc_bufsz - read_ptr) |
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block_size = async->prealloc_bufsz - read_ptr; |
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else |
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block_size = nbytes; |
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|
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memcpy(dest, src, block_size); |
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nbytes -= block_size; |
|
dest += block_size; |
|
read_ptr = 0; |
|
} |
|
} |
|
|
|
/** |
|
* comedi_buf_write_samples() - Write sample data to COMEDI buffer |
|
* @s: COMEDI subdevice. |
|
* @data: Pointer to source samples. |
|
* @nsamples: Number of samples to write. |
|
* |
|
* Write up to @nsamples samples to the COMEDI acquisition data buffer |
|
* associated with the subdevice, mark it as written and update the |
|
* acquisition scan progress. If there is not enough room for the specified |
|
* number of samples, the number of samples written is limited to the number |
|
* that will fit and the %COMEDI_CB_OVERFLOW event flag is set to cause the |
|
* acquisition to terminate with an overrun error. Set the %COMEDI_CB_BLOCK |
|
* event flag if any samples are written to cause waiting tasks to be woken |
|
* when the event flags are processed. |
|
* |
|
* Return: The amount of data written in bytes. |
|
*/ |
|
unsigned int comedi_buf_write_samples(struct comedi_subdevice *s, |
|
const void *data, unsigned int nsamples) |
|
{ |
|
unsigned int max_samples; |
|
unsigned int nbytes; |
|
|
|
/* |
|
* Make sure there is enough room in the buffer for all the samples. |
|
* If not, clamp the nsamples to the number that will fit, flag the |
|
* buffer overrun and add the samples that fit. |
|
*/ |
|
max_samples = comedi_bytes_to_samples(s, comedi_buf_write_n_unalloc(s)); |
|
if (nsamples > max_samples) { |
|
dev_warn(s->device->class_dev, "buffer overrun\n"); |
|
s->async->events |= COMEDI_CB_OVERFLOW; |
|
nsamples = max_samples; |
|
} |
|
|
|
if (nsamples == 0) |
|
return 0; |
|
|
|
nbytes = comedi_buf_write_alloc(s, |
|
comedi_samples_to_bytes(s, nsamples)); |
|
comedi_buf_memcpy_to(s, data, nbytes); |
|
comedi_buf_write_free(s, nbytes); |
|
comedi_inc_scan_progress(s, nbytes); |
|
s->async->events |= COMEDI_CB_BLOCK; |
|
|
|
return nbytes; |
|
} |
|
EXPORT_SYMBOL_GPL(comedi_buf_write_samples); |
|
|
|
/** |
|
* comedi_buf_read_samples() - Read sample data from COMEDI buffer |
|
* @s: COMEDI subdevice. |
|
* @data: Pointer to destination. |
|
* @nsamples: Maximum number of samples to read. |
|
* |
|
* Read up to @nsamples samples from the COMEDI acquisition data buffer |
|
* associated with the subdevice, mark it as read and update the acquisition |
|
* scan progress. Limit the number of samples read to the number available. |
|
* Set the %COMEDI_CB_BLOCK event flag if any samples are read to cause waiting |
|
* tasks to be woken when the event flags are processed. |
|
* |
|
* Return: The amount of data read in bytes. |
|
*/ |
|
unsigned int comedi_buf_read_samples(struct comedi_subdevice *s, |
|
void *data, unsigned int nsamples) |
|
{ |
|
unsigned int max_samples; |
|
unsigned int nbytes; |
|
|
|
/* clamp nsamples to the number of full samples available */ |
|
max_samples = comedi_bytes_to_samples(s, |
|
comedi_buf_read_n_available(s)); |
|
if (nsamples > max_samples) |
|
nsamples = max_samples; |
|
|
|
if (nsamples == 0) |
|
return 0; |
|
|
|
nbytes = comedi_buf_read_alloc(s, |
|
comedi_samples_to_bytes(s, nsamples)); |
|
comedi_buf_memcpy_from(s, data, nbytes); |
|
comedi_buf_read_free(s, nbytes); |
|
comedi_inc_scan_progress(s, nbytes); |
|
s->async->events |= COMEDI_CB_BLOCK; |
|
|
|
return nbytes; |
|
} |
|
EXPORT_SYMBOL_GPL(comedi_buf_read_samples);
|
|
|