--- /dev/null
+/*
+ * comedi_buf.c
+ *
+ * COMEDI - Linux Control and Measurement Device Interface
+ * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
+ * Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+
+#include "comedidev.h"
+#include "comedi_internal.h"
+
+#ifdef PAGE_KERNEL_NOCACHE
+#define COMEDI_PAGE_PROTECTION PAGE_KERNEL_NOCACHE
+#else
+#define COMEDI_PAGE_PROTECTION PAGE_KERNEL
+#endif
+
+static void comedi_buf_map_kref_release(struct kref *kref)
+{
+ struct comedi_buf_map *bm =
+ container_of(kref, struct comedi_buf_map, refcount);
+ struct comedi_buf_page *buf;
+ unsigned int i;
+
+ if (bm->page_list) {
+ for (i = 0; i < bm->n_pages; i++) {
+ buf = &bm->page_list[i];
+ clear_bit(PG_reserved,
+ &(virt_to_page(buf->virt_addr)->flags));
+ if (bm->dma_dir != DMA_NONE) {
+#ifdef CONFIG_HAS_DMA
+ dma_free_coherent(bm->dma_hw_dev,
+ PAGE_SIZE,
+ buf->virt_addr,
+ buf->dma_addr);
+#endif
+ } else {
+ free_page((unsigned long)buf->virt_addr);
+ }
+ }
+ vfree(bm->page_list);
+ }
+ if (bm->dma_dir != DMA_NONE)
+ put_device(bm->dma_hw_dev);
+ kfree(bm);
+}
+
+static void __comedi_buf_free(struct comedi_device *dev,
+ struct comedi_subdevice *s)
+{
+ struct comedi_async *async = s->async;
+ struct comedi_buf_map *bm;
+ unsigned long flags;
+
+ if (async->prealloc_buf) {
+ vunmap(async->prealloc_buf);
+ async->prealloc_buf = NULL;
+ async->prealloc_bufsz = 0;
+ }
+
+ spin_lock_irqsave(&s->spin_lock, flags);
+ bm = async->buf_map;
+ async->buf_map = NULL;
+ spin_unlock_irqrestore(&s->spin_lock, flags);
+ comedi_buf_map_put(bm);
+}
+
+static void __comedi_buf_alloc(struct comedi_device *dev,
+ struct comedi_subdevice *s,
+ unsigned n_pages)
+{
+ struct comedi_async *async = s->async;
+ struct page **pages = NULL;
+ struct comedi_buf_map *bm;
+ struct comedi_buf_page *buf;
+ unsigned long flags;
+ unsigned i;
+
+ if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {
+ dev_err(dev->class_dev,
+ "dma buffer allocation not supported\n");
+ return;
+ }
+
+ bm = kzalloc(sizeof(*async->buf_map), GFP_KERNEL);
+ if (!bm)
+ return;
+
+ kref_init(&bm->refcount);
+ spin_lock_irqsave(&s->spin_lock, flags);
+ async->buf_map = bm;
+ spin_unlock_irqrestore(&s->spin_lock, flags);
+ bm->dma_dir = s->async_dma_dir;
+ if (bm->dma_dir != DMA_NONE)
+ /* Need ref to hardware device to free buffer later. */
+ bm->dma_hw_dev = get_device(dev->hw_dev);
+
+ bm->page_list = vzalloc(sizeof(*buf) * n_pages);
+ if (bm->page_list)
+ pages = vmalloc(sizeof(struct page *) * n_pages);
+
+ if (!pages)
+ return;
+
+ for (i = 0; i < n_pages; i++) {
+ buf = &bm->page_list[i];
+ if (bm->dma_dir != DMA_NONE)
+#ifdef CONFIG_HAS_DMA
+ buf->virt_addr = dma_alloc_coherent(bm->dma_hw_dev,
+ PAGE_SIZE,
+ &buf->dma_addr,
+ GFP_KERNEL |
+ __GFP_COMP);
+#else
+ break;
+#endif
+ else
+ buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);
+ if (!buf->virt_addr)
+ break;
+
+ set_bit(PG_reserved, &(virt_to_page(buf->virt_addr)->flags));
+
+ pages[i] = virt_to_page(buf->virt_addr);
+ }
+ spin_lock_irqsave(&s->spin_lock, flags);
+ bm->n_pages = i;
+ spin_unlock_irqrestore(&s->spin_lock, flags);
+
+ /* vmap the prealloc_buf if all the pages were allocated */
+ if (i == n_pages)
+ async->prealloc_buf = vmap(pages, n_pages, VM_MAP,
+ COMEDI_PAGE_PROTECTION);
+
+ vfree(pages);
+}
+
+void comedi_buf_map_get(struct comedi_buf_map *bm)
+{
+ if (bm)
+ kref_get(&bm->refcount);
+}
+
+int comedi_buf_map_put(struct comedi_buf_map *bm)
+{
+ if (bm)
+ return kref_put(&bm->refcount, comedi_buf_map_kref_release);
+ return 1;
+}
+
+/* returns s->async->buf_map and increments its kref refcount */
+struct comedi_buf_map *
+comedi_buf_map_from_subdev_get(struct comedi_subdevice *s)
+{
+ struct comedi_async *async = s->async;
+ struct comedi_buf_map *bm = NULL;
+ unsigned long flags;
+
+ if (!async)
+ return NULL;
+
+ spin_lock_irqsave(&s->spin_lock, flags);
+ bm = async->buf_map;
+ /* only want it if buffer pages allocated */
+ if (bm && bm->n_pages)
+ comedi_buf_map_get(bm);
+ else
+ bm = NULL;
+ spin_unlock_irqrestore(&s->spin_lock, flags);
+
+ return bm;
+}
+
+bool comedi_buf_is_mmapped(struct comedi_subdevice *s)
+{
+ struct comedi_buf_map *bm = s->async->buf_map;
+
+ return bm && (atomic_read(&bm->refcount.refcount) > 1);
+}
+
+int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
+ unsigned long new_size)
+{
+ struct comedi_async *async = s->async;
+
+ /* Round up new_size to multiple of PAGE_SIZE */
+ new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;
+
+ /* if no change is required, do nothing */
+ if (async->prealloc_buf && async->prealloc_bufsz == new_size)
+ return 0;
+
+ /* deallocate old buffer */
+ __comedi_buf_free(dev, s);
+
+ /* allocate new buffer */
+ if (new_size) {
+ unsigned n_pages = new_size >> PAGE_SHIFT;
+
+ __comedi_buf_alloc(dev, s, n_pages);
+
+ if (!async->prealloc_buf) {
+ /* allocation failed */
+ __comedi_buf_free(dev, s);
+ return -ENOMEM;
+ }
+ }
+ async->prealloc_bufsz = new_size;
+
+ return 0;
+}
+
+void comedi_buf_reset(struct comedi_subdevice *s)
+{
+ struct comedi_async *async = s->async;
+
+ async->buf_write_alloc_count = 0;
+ async->buf_write_count = 0;
+ async->buf_read_alloc_count = 0;
+ async->buf_read_count = 0;
+
+ async->buf_write_ptr = 0;
+ async->buf_read_ptr = 0;
+
+ async->cur_chan = 0;
+ async->scans_done = 0;
+ async->scan_progress = 0;
+ async->munge_chan = 0;
+ async->munge_count = 0;
+ async->munge_ptr = 0;
+
+ async->events = 0;
+}
+
+static unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s)
+{
+ struct comedi_async *async = s->async;
+ unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
+
+ return free_end - async->buf_write_alloc_count;
+}
+
+/* allocates chunk for the writer from free buffer space */
+unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s,
+ unsigned int nbytes)
+{
+ struct comedi_async *async = s->async;
+ unsigned int available = comedi_buf_write_n_available(s);
+
+ if (nbytes > available)
+ nbytes = available;
+
+ async->buf_write_alloc_count += nbytes;
+
+ /*
+ * ensure the async buffer 'counts' are read and updated
+ * before we write data to the write-alloc'ed buffer space
+ */
+ smp_mb();
+
+ return nbytes;
+}
+EXPORT_SYMBOL_GPL(comedi_buf_write_alloc);
+
+/*
+ * munging is applied to data by core as it passes between user
+ * and kernel space
+ */
+static unsigned int comedi_buf_munge(struct comedi_subdevice *s,
+ unsigned int num_bytes)
+{
+ struct comedi_async *async = s->async;
+ unsigned int count = 0;
+ const unsigned num_sample_bytes = comedi_bytes_per_sample(s);
+
+ if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {
+ async->munge_count += num_bytes;
+ count = num_bytes;
+ } else {
+ /* don't munge partial samples */
+ num_bytes -= num_bytes % num_sample_bytes;
+ while (count < num_bytes) {
+ int block_size = num_bytes - count;
+ unsigned int buf_end;
+
+ buf_end = async->prealloc_bufsz - async->munge_ptr;
+ if (block_size > buf_end)
+ block_size = buf_end;
+
+ s->munge(s->device, s,
+ async->prealloc_buf + async->munge_ptr,
+ block_size, async->munge_chan);
+
+ /*
+ * ensure data is munged in buffer before the
+ * async buffer munge_count is incremented
+ */
+ smp_wmb();
+
+ async->munge_chan += block_size / num_sample_bytes;
+ async->munge_chan %= async->cmd.chanlist_len;
+ async->munge_count += block_size;
+ async->munge_ptr += block_size;
+ async->munge_ptr %= async->prealloc_bufsz;
+ count += block_size;
+ }
+ }
+
+ return count;
+}
+
+unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s)
+{
+ struct comedi_async *async = s->async;
+
+ return async->buf_write_alloc_count - async->buf_write_count;
+}
+
+/* transfers a chunk from writer to filled buffer space */
+unsigned int comedi_buf_write_free(struct comedi_subdevice *s,
+ unsigned int nbytes)
+{
+ struct comedi_async *async = s->async;
+ unsigned int allocated = comedi_buf_write_n_allocated(s);
+
+ if (nbytes > allocated)
+ nbytes = allocated;
+
+ async->buf_write_count += nbytes;
+ async->buf_write_ptr += nbytes;
+ comedi_buf_munge(s, async->buf_write_count - async->munge_count);
+ if (async->buf_write_ptr >= async->prealloc_bufsz)
+ async->buf_write_ptr %= async->prealloc_bufsz;
+
+ return nbytes;
+}
+EXPORT_SYMBOL_GPL(comedi_buf_write_free);
+
+unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s)
+{
+ struct comedi_async *async = s->async;
+ unsigned num_bytes;
+
+ if (!async)
+ return 0;
+
+ num_bytes = async->munge_count - async->buf_read_count;
+
+ /*
+ * ensure the async buffer 'counts' are read before we
+ * attempt to read data from the buffer
+ */
+ smp_rmb();
+
+ return num_bytes;
+}
+EXPORT_SYMBOL_GPL(comedi_buf_read_n_available);
+
+/* allocates a chunk for the reader from filled (and munged) buffer space */
+unsigned int comedi_buf_read_alloc(struct comedi_subdevice *s,
+ unsigned int nbytes)
+{
+ struct comedi_async *async = s->async;
+ unsigned int available;
+
+ available = async->munge_count - async->buf_read_alloc_count;
+ if (nbytes > available)
+ nbytes = available;
+
+ async->buf_read_alloc_count += nbytes;
+
+ /*
+ * ensure the async buffer 'counts' are read before we
+ * attempt to read data from the read-alloc'ed buffer space
+ */
+ smp_rmb();
+
+ return nbytes;
+}
+EXPORT_SYMBOL_GPL(comedi_buf_read_alloc);
+
+static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async)
+{
+ return async->buf_read_alloc_count - async->buf_read_count;
+}
+
+/* transfers control of a chunk from reader to free buffer space */
+unsigned int comedi_buf_read_free(struct comedi_subdevice *s,
+ unsigned int nbytes)
+{
+ struct comedi_async *async = s->async;
+ unsigned int allocated;
+
+ /*
+ * ensure data has been read out of buffer before
+ * the async read count is incremented
+ */
+ smp_mb();
+
+ allocated = comedi_buf_read_n_allocated(async);
+ if (nbytes > allocated)
+ nbytes = allocated;
+
+ async->buf_read_count += nbytes;
+ async->buf_read_ptr += nbytes;
+ async->buf_read_ptr %= async->prealloc_bufsz;
+ return nbytes;
+}
+EXPORT_SYMBOL_GPL(comedi_buf_read_free);
+
+static void comedi_buf_memcpy_to(struct comedi_subdevice *s,
+ const void *data, unsigned int num_bytes)
+{
+ struct comedi_async *async = s->async;
+ unsigned int write_ptr = async->buf_write_ptr;
+
+ while (num_bytes) {
+ unsigned int block_size;
+
+ if (write_ptr + num_bytes > async->prealloc_bufsz)
+ block_size = async->prealloc_bufsz - write_ptr;
+ else
+ block_size = num_bytes;
+
+ memcpy(async->prealloc_buf + write_ptr, data, block_size);
+
+ data += block_size;
+ num_bytes -= block_size;
+
+ write_ptr = 0;
+ }
+}
+
+static void comedi_buf_memcpy_from(struct comedi_subdevice *s,
+ void *dest, unsigned int nbytes)
+{
+ void *src;
+ struct comedi_async *async = s->async;
+ unsigned int read_ptr = async->buf_read_ptr;
+
+ while (nbytes) {
+ unsigned int block_size;
+
+ src = async->prealloc_buf + read_ptr;
+
+ if (nbytes >= async->prealloc_bufsz - read_ptr)
+ block_size = async->prealloc_bufsz - read_ptr;
+ else
+ block_size = nbytes;
+
+ memcpy(dest, src, block_size);
+ nbytes -= block_size;
+ dest += block_size;
+ read_ptr = 0;
+ }
+}
+
+/**
+ * comedi_buf_write_samples - write sample data to comedi buffer
+ * @s: comedi_subdevice struct
+ * @data: samples
+ * @nsamples: number of samples
+ *
+ * Writes nsamples to the comedi buffer associated with the subdevice, marks
+ * it as written and updates the acquisition scan progress.
+ *
+ * Returns 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_available(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 struct
+ * @data: destination
+ * @nsamples: maximum number of samples to read
+ *
+ * Reads up to nsamples from the comedi buffer associated with the subdevice,
+ * marks it as read and updates the acquisition scan progress.
+ *
+ * Returns 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);
Code Review / kvmfornfv.git / blobdiff