/usr/include/xenomai/analogy/buffer.h is in libxenomai-dev 2.6.4+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* @file
* Analogy for Linux, buffer related features
*
* Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
* Copyright (C) 2008 Alexis Berlemont <alexis.berlemont@free.fr>
*
* Xenomai 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.
*
* Xenomai 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 Xenomai; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef __ANALOGY_BUFFER_H__
#define __ANALOGY_BUFFER_H__
#ifndef DOXYGEN_CPP
#ifdef __KERNEL__
#include <linux/version.h>
#include <linux/mm.h>
#include <rtdm/rtdm_driver.h>
#include <analogy/os_facilities.h>
#include <analogy/context.h>
/* --- Events bits / flags --- */
#define A4L_BUF_EOBUF_NR 0
#define A4L_BUF_EOBUF (1 << A4L_BUF_EOBUF_NR)
#define A4L_BUF_ERROR_NR 1
#define A4L_BUF_ERROR (1 << A4L_BUF_ERROR_NR)
#define A4L_BUF_EOA_NR 2
#define A4L_BUF_EOA (1 << A4L_BUF_EOA_NR)
/* --- Status bits / flags --- */
#define A4L_BUF_BULK_NR 8
#define A4L_BUF_BULK (1 << A4L_BUF_BULK_NR)
#define A4L_BUF_MAP_NR 9
#define A4L_BUF_MAP (1 << A4L_BUF_MAP_NR)
struct a4l_subdevice;
/* Buffer descriptor structure */
struct a4l_buffer {
/* Added by the structure update */
struct a4l_subdevice *subd;
/* Buffer's first virtual page pointer */
void *buf;
/* Buffer's global size */
unsigned long size;
/* Tab containing buffer's pages pointers */
unsigned long *pg_list;
/* RT/NRT synchronization element */
a4l_sync_t sync;
/* Counters needed for transfer */
unsigned long end_count;
unsigned long prd_count;
unsigned long cns_count;
unsigned long tmp_count;
/* Status + events occuring during transfer */
unsigned long flags;
/* Command on progress */
a4l_cmd_t *cur_cmd;
/* Munge counter */
unsigned long mng_count;
/* Theshold below which the user process should not be
awakened */
unsigned long wake_count;
};
typedef struct a4l_buffer a4l_buf_t;
/* --- Static inline functions related with
user<->kernel data transfers --- */
/* The function __produce is an inline function which copies data into
the asynchronous buffer and takes care of the non-contiguous issue
when looping. This function is used in read and write operations */
static inline int __produce(a4l_cxt_t *cxt,
a4l_buf_t *buf, void *pin, unsigned long count)
{
unsigned long start_ptr = (buf->prd_count % buf->size);
unsigned long tmp_cnt = count;
int ret = 0;
while (ret == 0 && tmp_cnt != 0) {
/* Check the data copy can be performed contiguously */
unsigned long blk_size = (start_ptr + tmp_cnt > buf->size) ?
buf->size - start_ptr : tmp_cnt;
/* Perform the copy */
if (cxt == NULL)
memcpy(buf->buf + start_ptr, pin, blk_size);
else
ret = rtdm_safe_copy_from_user(cxt->user_info,
buf->buf + start_ptr,
pin, blk_size);
/* Update pointers/counts */
pin += blk_size;
tmp_cnt -= blk_size;
start_ptr = 0;
}
return ret;
}
/* The function __consume is an inline function which copies data from
the asynchronous buffer and takes care of the non-contiguous issue
when looping. This function is used in read and write operations */
static inline int __consume(a4l_cxt_t *cxt,
a4l_buf_t *buf, void *pout, unsigned long count)
{
unsigned long start_ptr = (buf->cns_count % buf->size);
unsigned long tmp_cnt = count;
int ret = 0;
while (ret == 0 && tmp_cnt != 0) {
/* Check the data copy can be performed contiguously */
unsigned long blk_size = (start_ptr + tmp_cnt > buf->size) ?
buf->size - start_ptr : tmp_cnt;
/* Perform the copy */
if (cxt == NULL)
memcpy(pout, buf->buf + start_ptr, blk_size);
else
ret = rtdm_safe_copy_to_user(cxt->user_info,
pout,
buf->buf + start_ptr,
blk_size);
/* Update pointers/counts */
pout += blk_size;
tmp_cnt -= blk_size;
start_ptr = 0;
}
return ret;
}
/* The function __munge is an inline function which calls the
subdevice specific munge callback on contiguous windows within the
whole buffer. This function is used in read and write operations */
static inline void __munge(struct a4l_subdevice * subd,
void (*munge) (struct a4l_subdevice *,
void *, unsigned long),
a4l_buf_t * buf, unsigned long count)
{
unsigned long start_ptr = (buf->mng_count % buf->size);
unsigned long tmp_cnt = count;
while (tmp_cnt != 0) {
/* Check the data copy can be performed contiguously */
unsigned long blk_size = (start_ptr + tmp_cnt > buf->size) ?
buf->size - start_ptr : tmp_cnt;
/* Perform the munge operation */
munge(subd, buf->buf + start_ptr, blk_size);
/* Update the start pointer and the count */
tmp_cnt -= blk_size;
start_ptr = 0;
}
}
/* The function __handle_event can only be called from process context
(not interrupt service routine). It allows the client process to
retrieve the buffer status which has been updated by the driver */
static inline int __handle_event(a4l_buf_t * buf)
{
int ret = 0;
/* The event "End of acquisition" must not be cleaned
before the complete flush of the buffer */
if (test_bit(A4L_BUF_EOA_NR, &buf->flags)) {
ret = -ENOENT;
}
if (test_bit(A4L_BUF_ERROR_NR, &buf->flags)) {
ret = -EPIPE;
}
return ret;
}
/* --- Counters management functions --- */
/* Here, we may wonder why we need more than two counters / pointers.
Theoretically, we only need two counters (or two pointers):
- one which tells where the reader should be within the buffer
- one which tells where the writer should be within the buffer
With these two counters (or pointers), we just have to check that
the writer does not overtake the reader inside the ring buffer
BEFORE any read / write operations.
However, if one element is a DMA controller, we have to be more
careful. Generally a DMA transfer occurs like this:
DMA shot
|-> then DMA interrupt
|-> then DMA soft handler which checks the counter
So, the checkings occur AFTER the write operations.
Let's take an example: the reader is a software task and the writer
is a DMA controller. At the end of the DMA shot, the write counter
is higher than the read counter. Unfortunately, a read operation
occurs between the DMA shot and the DMA interrupt, so the handler
will not notice that an overflow occured.
That is why tmp_count comes into play: tmp_count records the
read/consumer current counter before the next DMA shot and once the
next DMA shot is done, we check that the updated writer/producer
counter is not higher than tmp_count. Thus we are sure that the DMA
writer has not overtaken the reader because it was not able to
overtake the n-1 value. */
static inline int __pre_abs_put(a4l_buf_t * buf, unsigned long count)
{
if (count - buf->tmp_count > buf->size) {
set_bit(A4L_BUF_ERROR_NR, &buf->flags);
return -EPIPE;
}
buf->tmp_count = buf->cns_count;
return 0;
}
static inline int __pre_put(a4l_buf_t * buf, unsigned long count)
{
return __pre_abs_put(buf, buf->tmp_count + count);
}
static inline int __pre_abs_get(a4l_buf_t * buf, unsigned long count)
{
/* The first time, we expect the buffer to be properly filled
before the trigger occurence; by the way, we need tmp_count to
have been initialized and tmp_count is updated right here */
if (buf->tmp_count == 0 || buf->cns_count == 0)
goto out;
/* At the end of the acquisition, the user application has
written the defined amount of data into the buffer; so the
last time, the DMA channel can easily overtake the tmp
frontier because no more data were sent from user space;
therefore no useless alarm should be sent */
if (buf->end_count != 0 && (long)(count - buf->end_count) > 0)
goto out;
/* Once the exception are passed, we check that the DMA
transfer has not overtaken the last record of the production
count (tmp_count was updated with prd_count the last time
__pre_abs_get was called). We must understand that we cannot
compare the current DMA count with the current production
count because even if, right now, the production count is
higher than the DMA count, it does not mean that the DMA count
was not greater a few cycles before; in such case, the DMA
channel would have retrieved the wrong data */
if ((long)(count - buf->tmp_count) > 0) {
set_bit(A4L_BUF_ERROR_NR, &buf->flags);
return -EPIPE;
}
out:
buf->tmp_count = buf->prd_count;
return 0;
}
static inline int __pre_get(a4l_buf_t * buf, unsigned long count)
{
return __pre_abs_get(buf, buf->tmp_count + count);
}
static inline int __abs_put(a4l_buf_t * buf, unsigned long count)
{
unsigned long old = buf->prd_count;
if ((long)(buf->prd_count - count) >= 0)
return -EINVAL;
buf->prd_count = count;
if ((old / buf->size) != (count / buf->size))
set_bit(A4L_BUF_EOBUF_NR, &buf->flags);
if (buf->end_count != 0 && (long)(count - buf->end_count) >= 0)
set_bit(A4L_BUF_EOA_NR, &buf->flags);
return 0;
}
static inline int __put(a4l_buf_t * buf, unsigned long count)
{
return __abs_put(buf, buf->prd_count + count);
}
static inline int __abs_get(a4l_buf_t * buf, unsigned long count)
{
unsigned long old = buf->cns_count;
if ((long)(buf->cns_count - count) >= 0)
return -EINVAL;
buf->cns_count = count;
if ((old / buf->size) != count / buf->size)
set_bit(A4L_BUF_EOBUF_NR, &buf->flags);
if (buf->end_count != 0 && (long)(count - buf->end_count) >= 0)
set_bit(A4L_BUF_EOA_NR, &buf->flags);
return 0;
}
static inline int __get(a4l_buf_t * buf, unsigned long count)
{
return __abs_get(buf, buf->cns_count + count);
}
static inline unsigned long __count_to_put(a4l_buf_t * buf)
{
unsigned long ret;
if ((long) (buf->size + buf->cns_count - buf->prd_count) > 0)
ret = buf->size + buf->cns_count - buf->prd_count;
else
ret = 0;
return ret;
}
static inline unsigned long __count_to_get(a4l_buf_t * buf)
{
unsigned long ret;
/* If the acquisition is unlimited (end_count == 0), we must
not take into account end_count */
if (buf->end_count == 0 || (long)(buf->end_count - buf->prd_count) > 0)
ret = buf->prd_count;
else
ret = buf->end_count;
if ((long)(ret - buf->cns_count) > 0)
ret -= buf->cns_count;
else
ret = 0;
return ret;
}
static inline unsigned long __count_to_end(a4l_buf_t * buf)
{
unsigned long ret = buf->end_count - buf->cns_count;
if (buf->end_count == 0)
return ULONG_MAX;
return ((long)ret) < 0 ? 0 : ret;
}
/* --- Buffer internal functions --- */
int a4l_alloc_buffer(a4l_buf_t *buf_desc, int buf_size);
void a4l_free_buffer(a4l_buf_t *buf_desc);
void a4l_init_buffer(a4l_buf_t * buf_desc);
void a4l_cleanup_buffer(a4l_buf_t * buf_desc);
int a4l_setup_buffer(a4l_cxt_t *cxt, a4l_cmd_t *cmd);
int a4l_cancel_buffer(a4l_cxt_t *cxt);
int a4l_buf_prepare_absput(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_commit_absput(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_prepare_put(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_commit_put(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_put(struct a4l_subdevice *subd,
void *bufdata, unsigned long count);
int a4l_buf_prepare_absget(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_commit_absget(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_prepare_get(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_commit_get(struct a4l_subdevice *subd,
unsigned long count);
int a4l_buf_get(struct a4l_subdevice *subd,
void *bufdata, unsigned long count);
int a4l_buf_evt(struct a4l_subdevice *subd, unsigned long evts);
unsigned long a4l_buf_count(struct a4l_subdevice *subd);
/* --- Current Command management function --- */
static inline a4l_cmd_t *a4l_get_cmd(a4l_subd_t *subd)
{
return (subd->buf) ? subd->buf->cur_cmd : NULL;
}
/* --- Munge related function --- */
int a4l_get_chan(struct a4l_subdevice *subd);
/* --- IOCTL / FOPS functions --- */
int a4l_ioctl_mmap(a4l_cxt_t * cxt, void *arg);
int a4l_ioctl_bufcfg(a4l_cxt_t * cxt, void *arg);
int a4l_ioctl_bufcfg2(a4l_cxt_t * cxt, void *arg);
int a4l_ioctl_bufinfo(a4l_cxt_t * cxt, void *arg);
int a4l_ioctl_bufinfo2(a4l_cxt_t * cxt, void *arg);
int a4l_ioctl_poll(a4l_cxt_t * cxt, void *arg);
ssize_t a4l_read_buffer(a4l_cxt_t * cxt, void *bufdata, size_t nbytes);
ssize_t a4l_write_buffer(a4l_cxt_t * cxt, const void *bufdata, size_t nbytes);
int a4l_select(a4l_cxt_t *cxt,
rtdm_selector_t *selector,
enum rtdm_selecttype type, unsigned fd_index);
#endif /* __KERNEL__ */
/* MMAP ioctl argument structure */
struct a4l_mmap_arg {
unsigned int idx_subd;
unsigned long size;
void *ptr;
};
typedef struct a4l_mmap_arg a4l_mmap_t;
/* Constants related with buffer size
(might be used with BUFCFG ioctl) */
#define A4L_BUF_MAXSIZE 0x1000000
#define A4L_BUF_DEFSIZE 0x10000
#define A4L_BUF_DEFMAGIC 0xffaaff55
/* BUFCFG ioctl argument structure */
struct a4l_buffer_config {
/* NOTE: with the last buffer implementation, the field
idx_subd became useless; the buffer are now
per-context. So, the buffer size configuration is specific
to an opened device. There is a little exception: we can
define a default buffer size for a device.
So far, a hack is used to implement the configuration of
the default buffer size */
unsigned int idx_subd;
unsigned long buf_size;
};
typedef struct a4l_buffer_config a4l_bufcfg_t;
/* BUFINFO ioctl argument structure */
struct a4l_buffer_info {
unsigned int idx_subd;
unsigned long buf_size;
unsigned long rw_count;
};
typedef struct a4l_buffer_info a4l_bufinfo_t;
/* BUFCFG2 / BUFINFO2 ioctl argument structure */
struct a4l_buffer_config2 {
unsigned long wake_count;
unsigned long reserved[3];
};
typedef struct a4l_buffer_config2 a4l_bufcfg2_t;
/* POLL ioctl argument structure */
struct a4l_poll {
unsigned int idx_subd;
unsigned long arg;
};
typedef struct a4l_poll a4l_poll_t;
#endif /* !DOXYGEN_CPP */
#endif /* __ANALOGY_BUFFER_H__ */
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