424 lines
10 KiB
C
424 lines
10 KiB
C
/*
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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 <ds@schleef.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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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_free(struct comedi_device *dev,
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struct comedi_subdevice *s,
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unsigned n_pages)
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{
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struct comedi_async *async = s->async;
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struct comedi_buf_page *buf;
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unsigned i;
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if (async->prealloc_buf) {
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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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if (!async->buf_page_list)
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return;
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for (i = 0; i < n_pages; ++i) {
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buf = &async->buf_page_list[i];
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if (buf->virt_addr) {
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clear_bit(PG_reserved,
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&(virt_to_page(buf->virt_addr)->flags));
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if (s->async_dma_dir != DMA_NONE) {
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#ifdef CONFIG_HAS_DMA
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dma_free_coherent(dev->hw_dev,
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PAGE_SIZE,
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buf->virt_addr,
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buf->dma_addr);
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#endif
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} else {
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free_page((unsigned long)buf->virt_addr);
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}
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}
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}
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vfree(async->buf_page_list);
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async->buf_page_list = NULL;
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async->n_buf_pages = 0;
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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 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_page *buf;
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unsigned 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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async->buf_page_list = vzalloc(sizeof(*buf) * n_pages);
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if (async->buf_page_list)
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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 = &async->buf_page_list[i];
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if (s->async_dma_dir != DMA_NONE)
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#ifdef CONFIG_HAS_DMA
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buf->virt_addr = dma_alloc_coherent(dev->hw_dev,
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PAGE_SIZE,
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&buf->dma_addr,
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GFP_KERNEL |
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__GFP_COMP);
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#else
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break;
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#endif
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else
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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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set_bit(PG_reserved, &(virt_to_page(buf->virt_addr)->flags));
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pages[i] = virt_to_page(buf->virt_addr);
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}
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/* vmap the prealloc_buf if all the pages were allocated */
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if (i == n_pages)
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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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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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/* 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, async->n_buf_pages);
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/* allocate new buffer */
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if (new_size) {
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unsigned 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, n_pages);
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return -ENOMEM;
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}
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async->n_buf_pages = n_pages;
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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_async *async)
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{
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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->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_available(struct comedi_async *async)
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{
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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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static unsigned int __comedi_buf_write_alloc(struct comedi_async *async,
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unsigned int nbytes,
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int strict)
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{
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unsigned int available = comedi_buf_write_n_available(async);
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if (nbytes > available)
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nbytes = strict ? 0 : available;
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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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/* allocates chunk for the writer from free buffer space */
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unsigned int comedi_buf_write_alloc(struct comedi_async *async,
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unsigned int nbytes)
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{
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return __comedi_buf_write_alloc(async, nbytes, 0);
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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_async *async,
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unsigned int num_bytes)
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{
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struct comedi_subdevice *s = async->subdevice;
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unsigned int count = 0;
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const unsigned num_sample_bytes = 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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count = num_bytes;
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} else {
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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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}
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return count;
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}
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unsigned int comedi_buf_write_n_allocated(struct comedi_async *async)
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{
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return async->buf_write_alloc_count - async->buf_write_count;
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}
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/* transfers a chunk from writer to filled buffer space */
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unsigned int comedi_buf_write_free(struct comedi_async *async,
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unsigned int nbytes)
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{
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unsigned int allocated = comedi_buf_write_n_allocated(async);
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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(async, 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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unsigned int comedi_buf_read_n_available(struct comedi_async *async)
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{
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unsigned 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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/* allocates a chunk for the reader from filled (and munged) buffer space */
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unsigned int comedi_buf_read_alloc(struct comedi_async *async,
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unsigned int nbytes)
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{
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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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/* transfers control of a chunk from reader to free buffer space */
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unsigned int comedi_buf_read_free(struct comedi_async *async,
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unsigned int nbytes)
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{
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unsigned int allocated;
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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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int comedi_buf_put(struct comedi_async *async, short x)
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{
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unsigned int n = __comedi_buf_write_alloc(async, sizeof(short), 1);
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if (n < sizeof(short)) {
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async->events |= COMEDI_CB_ERROR;
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return 0;
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}
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*(short *)(async->prealloc_buf + async->buf_write_ptr) = x;
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comedi_buf_write_free(async, sizeof(short));
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return 1;
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}
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EXPORT_SYMBOL_GPL(comedi_buf_put);
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int comedi_buf_get(struct comedi_async *async, short *x)
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{
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unsigned int n = comedi_buf_read_n_available(async);
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if (n < sizeof(short))
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return 0;
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comedi_buf_read_alloc(async, sizeof(short));
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*x = *(short *)(async->prealloc_buf + async->buf_read_ptr);
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comedi_buf_read_free(async, sizeof(short));
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return 1;
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}
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EXPORT_SYMBOL_GPL(comedi_buf_get);
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void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
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const void *data, unsigned int num_bytes)
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{
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unsigned int write_ptr = async->buf_write_ptr + offset;
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if (write_ptr >= async->prealloc_bufsz)
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write_ptr %= async->prealloc_bufsz;
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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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EXPORT_SYMBOL_GPL(comedi_buf_memcpy_to);
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void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
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void *dest, unsigned int nbytes)
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{
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void *src;
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unsigned int read_ptr = async->buf_read_ptr + offset;
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if (read_ptr >= async->prealloc_bufsz)
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read_ptr %= async->prealloc_bufsz;
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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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memcpy(dest, src, block_size);
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nbytes -= block_size;
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dest += block_size;
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read_ptr = 0;
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}
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}
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EXPORT_SYMBOL_GPL(comedi_buf_memcpy_from);
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