// SPDX-License-Identifier: GPL-2.0+
/*
* comedi_buf.c
*
* COMEDI - Linux Control and Measurement Device Interface
* Copyright (C) 1997-2000 David A. Schleef <[email protected]>
* Copyright (C) 2002 Frank Mori Hess <[email protected]>
*/
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/comedi/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) {
if (bm->dma_dir != DMA_NONE) {
/*
* DMA buffer was allocated as a single block.
* Address is in page_list[0].
*/
buf = &bm->page_list[0];
dma_free_coherent(bm->dma_hw_dev,
PAGE_SIZE * bm->n_pages,
buf->virt_addr, buf->dma_addr);
} else {
for (i = 0; i < bm->n_pages; i++) {
buf = &bm->page_list[i];
ClearPageReserved(virt_to_page(buf->virt_addr));
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) {
if (s->async_dma_dir == DMA_NONE)
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 struct comedi_buf_map *
comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir,
unsigned int n_pages)
{
struct comedi_buf_map *bm;
struct comedi_buf_page *buf;
unsigned int i;
bm = kzalloc(sizeof(*bm), GFP_KERNEL);
if (!bm)
return NULL;
kref_init(&bm->refcount);
bm->dma_dir = 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)
goto err;
if (bm->dma_dir != DMA_NONE) {
void *virt_addr;
dma_addr_t dma_addr;
/*
* Currently, the DMA buffer needs to be allocated as a
* single block so that it can be mmap()'ed.
*/
virt_addr = dma_alloc_coherent(bm->dma_hw_dev,
PAGE_SIZE * n_pages, &dma_addr,
GFP_KERNEL);
if (!virt_addr)
goto err;
for (i = 0; i < n_pages; i++) {
buf = &bm->page_list[i];
buf->virt_addr = virt_addr + (i << PAGE_SHIFT);
buf->dma_addr = dma_addr + (i << PAGE_SHIFT);
}
bm->n_pages = i;
} else {
for (i = 0; i < n_pages; i++) {
buf = &bm->page_list[i];
buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);
if (!buf->virt_addr)
break;
SetPageReserved(virt_to_page(buf->virt_addr));
}
bm->n_pages = i;
if (i < n_pages)
goto err;
}
return bm;
err:
comedi_buf_map_put(bm);
return NULL;
}
static void __comedi_buf_alloc(struct comedi_device *dev,
struct comedi_subdevice *s,
unsigned int 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 int 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 = comedi_buf_map_alloc(dev, s->async_dma_dir, n_pages);
if (!bm)
return;
spin_lock_irqsave(&s->spin_lock, flags);
async->buf_map = bm;
spin_unlock_irqrestore(&s->spin_lock, flags);
if (bm->dma_dir != DMA_NONE) {
/*
* DMA buffer was allocated as a single block.
* Address is in page_list[0].
*/
buf = &bm->page_list[0];
async->prealloc_buf = buf->virt_addr;
} else {
pages = vmalloc(sizeof(struct page *) * n_pages);
if (!pages)
return;
for (i = 0; i < n_pages; i++) {
buf = &bm->page_list[i];
pages[i] = virt_to_page(buf->virt_addr);
}
/* vmap the pages to prealloc_buf */
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;
}
/* helper for "access" vm operation */
int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset,
void *buf, int len, int write)
{
unsigned int pgoff = offset_in_page(offset);
unsigned long pg = offset >> PAGE_SHIFT;
int done = 0;
while (done < len && pg < bm->n_pages) {
int l = min_t(int, len - done, PAGE_SIZE - pgoff);
void *b = bm->page_list[pg].virt_addr + pgoff;
if (write)
memcpy(b, buf, l);
else
memcpy(buf, b, l);
buf += l;
done += l;
pg++;
pgoff = 0;
}
return done;
}
/* 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 && (kref_read(&bm->refcount) > 1);
}
int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
unsigned long new_size)
{
struct comedi_async *async = s->async;
lockdep_assert_held(&dev->mutex);
/* 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 int 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_unalloc(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;
}
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_count;
}
/**
* comedi_buf_write_alloc() - Reserve buffer space for writing
* @s: COMEDI subdevice.
* @nbytes: Maximum space to reserve in bytes.
*
* Reserve up to @nbytes bytes of space to be written in the COMEDI acquisition
* data buffer associated with the subdevice. The amount reserved is limited
* by the space available.
*
* Return: The amount of space reserved in bytes.
*/
unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s,
unsigned int nbytes)
{
struct comedi_async *async = s->async;
unsigned int unalloc = comedi_buf_write_n_unalloc(s);
if (nbytes > unalloc)
nbytes = unalloc;
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 int num_sample_bytes = comedi_bytes_per_sample(s);
if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) {
async->munge_count += num_bytes;
return num_bytes;
}
/* 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;
}
/**
* comedi_buf_write_free() - Free buffer space after it is written
* @s: COMEDI subdevice.
* @nbytes: Maximum space to free in bytes.
*
* Free up to @nbytes bytes of space previously reserved for writing in the
* COMEDI acquisition data buffer associated with the subdevice. The amount of
* space freed is limited to the amount that was reserved. The freed space is
* assumed to have been filled with sample data by the writer.
*
* If the samples in the freed space need to be "munged", do so here. The
* freed space becomes available for allocation by the reader.
*
* Return: The amount of space freed in bytes.
*/
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);
/**
* comedi_buf_read_n_available() - Determine amount of readable buffer space
* @s: COMEDI subdevice.
*
* Determine the amount of readable buffer space in the COMEDI acquisition data
* buffer associated with the subdevice. The readable buffer space is that
* which has been freed by the writer and "munged" to the sample data format
* expected by COMEDI if necessary.
*
* Return: The amount of readable buffer space.
*/
unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s)
{
struct comedi_async *async = s->async;
unsigned int 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);
/**
* comedi_buf_read_alloc() - Reserve buffer space for reading
* @s: COMEDI subdevice.
* @nbytes: Maximum space to reserve in bytes.
*
* Reserve up to @nbytes bytes of previously written and "munged" buffer space
* for reading in the COMEDI acquisition data buffer associated with the
* subdevice. The amount reserved is limited to the space available. The
* reader can read from the reserved space and then free it. A reader is also
* allowed to read from the space before reserving it as long as it determines
* the amount of readable data available, but the space needs to be marked as
* reserved before it can be freed.
*
* Return: The amount of space reserved in bytes.
*/
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;
}
/**
* comedi_buf_read_free() - Free buffer space after it has been read
* @s: COMEDI subdevice.
* @nbytes: Maximum space to free in bytes.
*
* Free up to @nbytes bytes of buffer space previously reserved for reading in
* the COMEDI acquisition data buffer associated with the subdevice. The
* amount of space freed is limited to the amount that was reserved.
*
* The freed space becomes available for allocation by the writer.
*
* Return: The amount of space freed in bytes.
*/
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.
* @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);
Codebase Browser
linux