staging: comedi: separate out comedi_buf_* functions

Create a new file, comedi_buf.c, to hold all the comedi_async buffer
functions. Currently they are all in drivers.c and really don't have
any association with that source file.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 421 insertions, 0 deletions

diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
new file mode 100644
index 00000000000..fe2dcae805b
--- /dev/null
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -0,0 +1,421 @@
+/*
+ * comedi_buf.c
+ *
+ * COMEDI - Linux Control and Measurement Device Interface
+ * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "comedidev.h"
+#include "comedi_internal.h"
+
+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 */
+	if (async->prealloc_buf) {
+		vunmap(async->prealloc_buf);
+		async->prealloc_buf = NULL;
+		async->prealloc_bufsz = 0;
+	}
+	if (async->buf_page_list) {
+		unsigned i;
+		for (i = 0; i < async->n_buf_pages; ++i) {
+			if (async->buf_page_list[i].virt_addr) {
+				clear_bit(PG_reserved,
+					&(virt_to_page(async->buf_page_list[i].
+							virt_addr)->flags));
+				if (s->async_dma_dir != DMA_NONE) {
+					dma_free_coherent(dev->hw_dev,
+							  PAGE_SIZE,
+							  async->
+							  buf_page_list
+							  [i].virt_addr,
+							  async->
+							  buf_page_list
+							  [i].dma_addr);
+				} else {
+					free_page((unsigned long)
+						  async->buf_page_list[i].
+						  virt_addr);
+				}
+			}
+		}
+		vfree(async->buf_page_list);
+		async->buf_page_list = NULL;
+		async->n_buf_pages = 0;
+	}
+	/*  allocate new buffer */
+	if (new_size) {
+		unsigned i = 0;
+		unsigned n_pages = new_size >> PAGE_SHIFT;
+		struct page **pages = NULL;
+
+		async->buf_page_list =
+		    vzalloc(sizeof(struct comedi_buf_page) * n_pages);
+		if (async->buf_page_list)
+			pages = vmalloc(sizeof(struct page *) * n_pages);
+
+		if (pages) {
+			for (i = 0; i < n_pages; i++) {
+				if (s->async_dma_dir != DMA_NONE) {
+					async->buf_page_list[i].virt_addr =
+					    dma_alloc_coherent(dev->hw_dev,
+							       PAGE_SIZE,
+							       &async->
+							       buf_page_list
+							       [i].dma_addr,
+							       GFP_KERNEL |
+							       __GFP_COMP);
+				} else {
+					async->buf_page_list[i].virt_addr =
+					    (void *)
+					    get_zeroed_page(GFP_KERNEL);
+				}
+				if (async->buf_page_list[i].virt_addr == NULL)
+					break;
+
+				set_bit(PG_reserved,
+					&(virt_to_page(async->buf_page_list[i].
+							virt_addr)->flags));
+				pages[i] = virt_to_page(async->buf_page_list[i].
+								virt_addr);
+			}
+		}
+		if (i == n_pages) {
+			async->prealloc_buf =
+#ifdef PAGE_KERNEL_NOCACHE
+			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NOCACHE);
+#else
+			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);
+#endif
+		}
+		vfree(pages);
+
+		if (async->prealloc_buf == NULL) {
+			/* Some allocation failed above. */
+			if (async->buf_page_list) {
+				for (i = 0; i < n_pages; i++) {
+					if (async->buf_page_list[i].virt_addr ==
+					    NULL) {
+						break;
+					}
+					clear_bit(PG_reserved,
+						&(virt_to_page(async->
+							buf_page_list[i].
+							virt_addr)->flags));
+					if (s->async_dma_dir != DMA_NONE) {
+						dma_free_coherent(dev->hw_dev,
+								  PAGE_SIZE,
+								  async->
+								  buf_page_list
+								  [i].virt_addr,
+								  async->
+								  buf_page_list
+								  [i].dma_addr);
+					} else {
+						free_page((unsigned long)
+							  async->buf_page_list
+							  [i].virt_addr);
+					}
+				}
+				vfree(async->buf_page_list);
+				async->buf_page_list = NULL;
+			}
+			return -ENOMEM;
+		}
+		async->n_buf_pages = n_pages;
+	}
+	async->prealloc_bufsz = new_size;
+
+	return 0;
+}
+
+void comedi_reset_async_buf(struct comedi_async *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->scan_progress = 0;
+	async->munge_chan = 0;
+	async->munge_count = 0;
+	async->munge_ptr = 0;
+
+	async->events = 0;
+}
+
+unsigned int comedi_buf_write_n_available(struct comedi_async *async)
+{
+	unsigned int free_end;
+	unsigned int nbytes;
+
+	if (async == NULL)
+		return 0;
+
+	free_end = async->buf_read_count + async->prealloc_bufsz;
+	nbytes = free_end - async->buf_write_alloc_count;
+	nbytes -= nbytes % bytes_per_sample(async->subdevice);
+	/* barrier insures the read of buf_read_count in this
+	   query occurs before any following writes to the buffer which
+	   might be based on the return value from this query.
+	 */
+	smp_mb();
+	return nbytes;
+}
+
+/* allocates chunk for the writer from free buffer space */
+unsigned int comedi_buf_write_alloc(struct comedi_async *async,
+				    unsigned int nbytes)
+{
+	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
+
+	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
+		nbytes = free_end - async->buf_write_alloc_count;
+
+	async->buf_write_alloc_count += nbytes;
+	/* barrier insures the read of buf_read_count above occurs before
+	   we write data to the write-alloc'ed buffer space */
+	smp_mb();
+	return nbytes;
+}
+EXPORT_SYMBOL(comedi_buf_write_alloc);
+
+/* allocates nothing unless it can completely fulfill the request */
+unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async,
+					   unsigned int nbytes)
+{
+	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
+
+	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
+		nbytes = 0;
+
+	async->buf_write_alloc_count += nbytes;
+	/* barrier insures the read of buf_read_count above occurs before
+	   we write data to the write-alloc'ed buffer space */
+	smp_mb();
+	return nbytes;
+}
+
+/* munging is applied to data by core as it passes between user
+ * and kernel space */
+static unsigned int comedi_buf_munge(struct comedi_async *async,
+				     unsigned int num_bytes)
+{
+	struct comedi_subdevice *s = async->subdevice;
+	unsigned int count = 0;
+	const unsigned num_sample_bytes = bytes_per_sample(s);
+
+	if (s->munge == NULL || (async->cmd.flags & CMDF_RAWDATA)) {
+		async->munge_count += num_bytes;
+		BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);
+		return num_bytes;
+	}
+	/* don't munge partial samples */
+	num_bytes -= num_bytes % num_sample_bytes;
+	while (count < num_bytes) {
+		int block_size;
+
+		block_size = num_bytes - count;
+		if (block_size < 0) {
+			dev_warn(s->device->class_dev,
+				 "%s: %s: bug! block_size is negative\n",
+				 __FILE__, __func__);
+			break;
+		}
+		if ((int)(async->munge_ptr + block_size -
+			  async->prealloc_bufsz) > 0)
+			block_size = async->prealloc_bufsz - async->munge_ptr;
+
+		s->munge(s->device, s, async->prealloc_buf + async->munge_ptr,
+			 block_size, async->munge_chan);
+
+		smp_wmb();	/* barrier insures data is munged in buffer
+				 * before munge_count is incremented */
+
+		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;
+	}
+	BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);
+	return count;
+}
+
+/* transfers a chunk from writer to filled buffer space */
+unsigned comedi_buf_write_free(struct comedi_async *async, unsigned int nbytes)
+{
+	if ((int)(async->buf_write_count + nbytes -
+		  async->buf_write_alloc_count) > 0) {
+		dev_info(async->subdevice->device->class_dev,
+			 "attempted to write-free more bytes than have been write-allocated.\n");
+		nbytes = async->buf_write_alloc_count - async->buf_write_count;
+	}
+	async->buf_write_count += nbytes;
+	async->buf_write_ptr += nbytes;
+	comedi_buf_munge(async, 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(comedi_buf_write_free);
+
+unsigned int comedi_buf_read_n_available(struct comedi_async *async)
+{
+	unsigned num_bytes;
+
+	if (async == NULL)
+		return 0;
+	num_bytes = async->munge_count - async->buf_read_count;
+	/* barrier insures the read of munge_count in this
+	   query occurs before any following reads of the buffer which
+	   might be based on the return value from this query.
+	 */
+	smp_rmb();
+	return num_bytes;
+}
+EXPORT_SYMBOL(comedi_buf_read_n_available);
+
+/* allocates a chunk for the reader from filled (and munged) buffer space */
+unsigned comedi_buf_read_alloc(struct comedi_async *async, unsigned nbytes)
+{
+	if ((int)(async->buf_read_alloc_count + nbytes - async->munge_count) >
+	    0) {
+		nbytes = async->munge_count - async->buf_read_alloc_count;
+	}
+	async->buf_read_alloc_count += nbytes;
+	/* barrier insures read of munge_count occurs before we actually read
+	   data out of buffer */
+	smp_rmb();
+	return nbytes;
+}
+EXPORT_SYMBOL(comedi_buf_read_alloc);
+
+/* transfers control of a chunk from reader to free buffer space */
+unsigned comedi_buf_read_free(struct comedi_async *async, unsigned int nbytes)
+{
+	/* barrier insures data has been read out of
+	 * buffer before read count is incremented */
+	smp_mb();
+	if ((int)(async->buf_read_count + nbytes -
+		  async->buf_read_alloc_count) > 0) {
+		dev_info(async->subdevice->device->class_dev,
+			 "attempted to read-free more bytes than have been read-allocated.\n");
+		nbytes = async->buf_read_alloc_count - async->buf_read_count;
+	}
+	async->buf_read_count += nbytes;
+	async->buf_read_ptr += nbytes;
+	async->buf_read_ptr %= async->prealloc_bufsz;
+	return nbytes;
+}
+EXPORT_SYMBOL(comedi_buf_read_free);
+
+int comedi_buf_put(struct comedi_async *async, short x)
+{
+	unsigned int n = comedi_buf_write_alloc_strict(async, sizeof(short));
+
+	if (n < sizeof(short)) {
+		async->events |= COMEDI_CB_ERROR;
+		return 0;
+	}
+	*(short *)(async->prealloc_buf + async->buf_write_ptr) = x;
+	comedi_buf_write_free(async, sizeof(short));
+	return 1;
+}
+EXPORT_SYMBOL(comedi_buf_put);
+
+int comedi_buf_get(struct comedi_async *async, short *x)
+{
+	unsigned int n = comedi_buf_read_n_available(async);
+
+	if (n < sizeof(short))
+		return 0;
+	comedi_buf_read_alloc(async, sizeof(short));
+	*x = *(short *)(async->prealloc_buf + async->buf_read_ptr);
+	comedi_buf_read_free(async, sizeof(short));
+	return 1;
+}
+EXPORT_SYMBOL(comedi_buf_get);
+
+void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,
+			  const void *data, unsigned int num_bytes)
+{
+	unsigned int write_ptr = async->buf_write_ptr + offset;
+
+	if (write_ptr >= async->prealloc_bufsz)
+		write_ptr %= async->prealloc_bufsz;
+
+	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;
+	}
+}
+EXPORT_SYMBOL(comedi_buf_memcpy_to);
+
+void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
+			    void *dest, unsigned int nbytes)
+{
+	void *src;
+	unsigned int read_ptr = async->buf_read_ptr + offset;
+
+	if (read_ptr >= async->prealloc_bufsz)
+		read_ptr %= async->prealloc_bufsz;
+
+	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;
+	}
+}
+EXPORT_SYMBOL(comedi_buf_memcpy_from);