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local-mmap.c
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local-mmap.c
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// SPDX-License-Identifier: LGPL-2.1-or-later
/*
* libiio - Library for interfacing industrial I/O (IIO) devices
*
* Copyright (C) 2022 Analog Devices, Inc.
* Author: Paul Cercueil <paul.cercueil@analog.com>
*/
#include "iio-private.h"
#include "local.h"
#include <errno.h>
#include <iio/iio.h>
#include <iio/iio-backend.h>
#include <iio/iio-debug.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <stdatomic.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <time.h>
#define container_of(ptr, type, member) \
((type *)(void *)((uintptr_t)(ptr) - offsetof(type, member)))
#define BLOCK_ALLOC_IOCTL _IOWR('i', 0xa0, struct block_alloc_req)
#define BLOCK_FREE_IOCTL _IO('i', 0xa1)
#define BLOCK_QUERY_IOCTL _IOWR('i', 0xa2, struct block)
#define BLOCK_ENQUEUE_IOCTL _IOWR('i', 0xa3, struct block)
#define BLOCK_DEQUEUE_IOCTL _IOWR('i', 0xa4, struct block)
#define BLOCK_FLAG_CYCLIC BIT(1)
struct block_alloc_req {
uint32_t type,
size,
count,
id;
};
struct block {
uint32_t id,
size,
bytes_used,
type,
flags,
offset;
uint64_t timestamp;
};
struct iio_buffer_impl_pdata {
atomic_uint_fast64_t mmap_block_mask;
atomic_uint_fast64_t mmap_enqueued_blocks_mask;
bool mmap_check_done;
bool cyclic_buffer_enqueued;
unsigned int nb_blocks;
};
struct iio_block_impl_pdata {
struct iio_block_pdata pdata;
struct block block;
unsigned int idx;
bool enqueued;
};
static struct iio_block_impl_pdata *
iio_block_get_impl(struct iio_block_pdata *pdata)
{
return container_of(pdata, struct iio_block_impl_pdata, pdata);
}
static bool local_is_mmap_api_supported(int fd)
{
/*
* For the BLOCK_ALLOC_IOCTL ioctl it is not possible to distinguish
* between an error during the allocation (e.g. incorrect size) or
* whether the high-speed interface is not supported. BLOCK_FREE_IOCTL does
* never fail if the device supports the high-speed interface, so we use it
* here. Calling it when no blocks are allocated the ioctl has no effect.
*/
return !ioctl_nointr(fd, BLOCK_FREE_IOCTL, NULL);
}
struct iio_block_pdata *
local_create_mmap_block(struct iio_buffer_pdata *pdata,
size_t size, void **data)
{
struct iio_buffer_impl_pdata *ppdata = pdata->pdata;
struct iio_block_impl_pdata *priv;
struct block_alloc_req req;
int ret;
if (!ppdata->mmap_check_done) {
pdata->mmap_supported = local_is_mmap_api_supported(pdata->fd);
ppdata->mmap_check_done = true;
}
if (!pdata->mmap_supported)
return iio_ptr(-ENOSYS);
priv = zalloc(sizeof(*priv));
if (!priv)
return iio_ptr(-ENOMEM);
if (ppdata->mmap_block_mask == (uint64_t) -1) {
/* 64 blocks is the maximum */
dev_err(pdata->dev, "64 blocks is the maximum with the MMAP API.\n");
ret = -EINVAL;
goto out_free_priv;
}
if (__builtin_popcountl(ppdata->mmap_block_mask) == ppdata->nb_blocks) {
/* All our allocated blocks are used; we need to create one more. */
priv->idx = ppdata->nb_blocks;
req.id = 0;
req.type = 0;
req.size = size;
req.count = 1;
ret = ioctl_nointr(pdata->fd, BLOCK_ALLOC_IOCTL, &req);
if (ret < 0)
goto out_free_priv;
ppdata->nb_blocks++;
} else {
/* One of our previously allocated blocks has been freed;
* reuse it now. */
/* XXX: This only works if the blocks are the same size... */
priv->idx = __builtin_ffsl(~ppdata->mmap_block_mask) - 1;
}
priv->block.id = priv->idx;
ret = ioctl_nointr(pdata->fd, BLOCK_QUERY_IOCTL, &priv->block);
if (ret < 0)
goto out_free_priv;
priv->pdata.data = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED,
pdata->fd, priv->block.offset);
if (priv->pdata.data == MAP_FAILED) {
ret = -errno;
goto out_free_priv;
}
priv->pdata.size = size;
priv->pdata.buf = pdata;
*data = priv->pdata.data;
ppdata->mmap_block_mask |= BIT(priv->idx);
return &priv->pdata;
out_free_priv:
free(priv);
return iio_ptr(ret);
}
void local_free_mmap_block(struct iio_block_pdata *pdata)
{
struct iio_block_impl_pdata *priv = iio_block_get_impl(pdata);
struct iio_buffer_pdata *buf = pdata->buf;
munmap(pdata->data, pdata->size);
if (!atomic_fetch_xor(&buf->pdata->mmap_block_mask, BIT(priv->idx))) {
ioctl_nointr(pdata->buf->fd, BLOCK_FREE_IOCTL, 0);
pdata->buf->pdata->nb_blocks = 0;
}
free(priv);
}
int local_enqueue_mmap_block(struct iio_block_pdata *pdata,
size_t bytes_used, bool cyclic)
{
struct iio_block_impl_pdata *priv = iio_block_get_impl(pdata);
struct iio_buffer_pdata *buf = pdata->buf;
int ret, fd = buf->fd;
uint_fast64_t mask;
if (cyclic) {
if (buf->pdata->cyclic_buffer_enqueued)
return -EBUSY;
priv->block.flags |= BLOCK_FLAG_CYCLIC;
}
if (bytes_used != priv->block.size && !iio_device_is_tx(buf->dev)) {
/* MMAP interface only supports bytes_used on TX */
return -EINVAL;
}
if (priv->enqueued) {
/* Already enqueued */
return -EPERM;
}
mask = atomic_fetch_or(&buf->pdata->mmap_enqueued_blocks_mask, BIT(priv->idx));
if (mask & BIT(priv->idx)) {
/* The block was marked as dequeued, but has been enqueued to
* the kernel? This case should never happen. */
priv->enqueued = true;
return 0;
}
priv->block.bytes_used = (uint32_t) bytes_used;
ret = ioctl_nointr(fd, BLOCK_ENQUEUE_IOCTL, &priv->block);
if (ret < 0) {
atomic_fetch_xor(&buf->pdata->mmap_enqueued_blocks_mask, BIT(priv->idx));
return ret;
}
if (cyclic)
buf->pdata->cyclic_buffer_enqueued = true;
priv->enqueued = true;
return 0;
}
int local_dequeue_mmap_block(struct iio_block_pdata *pdata, bool nonblock)
{
struct iio_block_impl_pdata *priv = iio_block_get_impl(pdata);
struct iio_buffer_pdata *buf = pdata->buf;
struct timespec start, *time_ptr = NULL;
struct block block;
int ret, fd = buf->fd;
if (!priv->enqueued) {
/* Already dequeued */
return -EPERM;
}
if (!nonblock) {
clock_gettime(CLOCK_MONOTONIC, &start);
time_ptr = &start;
}
for (;;) {
if (!(atomic_load(&buf->pdata->mmap_enqueued_blocks_mask) & BIT(priv->idx))) {
/* The block has been dequeued by a previous call to
* local_dequeue_mmap_block() for a different block. */
break;
}
ret = buffer_check_ready(buf, fd, POLLIN | POLLOUT, time_ptr);
if (ret < 0)
return ret;
ret = ioctl_nointr(fd, BLOCK_DEQUEUE_IOCTL, &block);
if (ret < 0)
return ret;
atomic_fetch_xor(&buf->pdata->mmap_enqueued_blocks_mask, BIT(block.id));
if (block.id == priv->idx)
break;
}
priv->enqueued = false;
return 0;
}
struct iio_buffer_impl_pdata * local_alloc_mmap_buffer_impl(void)
{
struct iio_buffer_impl_pdata *pdata;
pdata = zalloc(sizeof(*pdata));
if (!pdata)
return iio_ptr(-ENOMEM);
return pdata;
}