/*
* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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 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., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <strings.h>
#include <errno.h>
#include <ipxe/malloc.h>
#include <ipxe/iobuf.h>
/** @file
*
* I/O buffers
*
*/
/**
* Allocate I/O buffer with specified alignment and offset
*
* @v len Required length of buffer
* @v align Physical alignment
* @v offset Offset from physical alignment
* @ret iobuf I/O buffer, or NULL if none available
*
* @c align will be rounded up to the nearest power of two.
*/
struct io_buffer * alloc_iob_raw ( size_t len, size_t align, size_t offset ) {
struct io_buffer *iobuf;
size_t padding;
size_t threshold;
unsigned int align_log2;
void *data;
/* Calculate padding required below alignment boundary to
* ensure that a correctly aligned inline struct io_buffer
* could fit (regardless of the requested offset).
*/
padding = ( sizeof ( *iobuf ) + __alignof__ ( *iobuf ) - 1 );
/* Round up requested alignment to at least the size of the
* padding, to simplify subsequent calculations.
*/
if ( align < padding )
align = padding;
/* Round up alignment to the nearest power of two, avoiding
* a potentially undefined shift operation.
*/
align_log2 = fls ( align - 1 );
if ( align_log2 >= ( 8 * sizeof ( align ) ) )
return NULL;
align = ( 1UL << align_log2 );
/* Calculate length threshold */
assert ( align >= padding );
threshold = ( align - padding );
/* Allocate buffer plus an inline descriptor as a single unit,
* unless doing so would push the total size over the
* alignment boundary.
*/
if ( len <= threshold ) {
/* Round up buffer length to ensure that struct
* io_buffer is aligned.
*/
len += ( ( - len - offset ) & ( __alignof__ ( *iobuf ) - 1 ) );
/* Allocate memory for buffer plus descriptor */
data = malloc_dma_offset ( len + sizeof ( *iobuf ), align,
offset );
if ( ! data )
return NULL;
iobuf = ( data + len );
} else {
/* Allocate memory for buffer */
data = malloc_dma_offset ( len, align, offset );
if ( ! data )
return NULL;
/* Allocate memory for descriptor */
iobuf = malloc ( sizeof ( *iobuf ) );
if ( ! iobuf ) {
free_dma ( data, len );
return NULL;
}
}
/* Populate descriptor */
iobuf->head = iobuf->data = iobuf->tail = data;
iobuf->end = ( data + len );
return iobuf;
}
/**
* Allocate I/O buffer
*
* @v len Required length of buffer
* @ret iobuf I/O buffer, or NULL if none available
*
* The I/O buffer will be physically aligned on its own size (rounded
* up to the nearest power of two).
*/
struct io_buffer * alloc_iob ( size_t len ) {
/* Pad to minimum length */
if ( len < IOB_ZLEN )
len = IOB_ZLEN;
/* Align buffer on its own size to avoid potential problems
* with boundary-crossing DMA.
*/
return alloc_iob_raw ( len, len, 0 );
}
/**
* Free I/O buffer
*
* @v iobuf I/O buffer
*/
void free_iob ( struct io_buffer *iobuf ) {
size_t len;
/* Allow free_iob(NULL) to be valid */
if ( ! iobuf )
return;
/* Sanity checks */
assert ( iobuf->head <= iobuf->data );
assert ( iobuf->data <= iobuf->tail );
assert ( iobuf->tail <= iobuf->end );
/* Free buffer */
len = ( iobuf->end - iobuf->head );
if ( iobuf->end == iobuf ) {
/* Descriptor is inline */
free_dma ( iobuf->head, ( len + sizeof ( *iobuf ) ) );
} else {
/* Descriptor is detached */
free_dma ( iobuf->head, len );
free ( iobuf );
}
}
/**
* Ensure I/O buffer has sufficient headroom
*
* @v iobuf I/O buffer
* @v len Required headroom
*
* This function currently only checks for the required headroom; it
* does not reallocate the I/O buffer if required. If we ever have a
* code path that requires this functionality, it's a fairly trivial
* change to make.
*/
int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len ) {
if ( iob_headroom ( iobuf ) >= len )
return 0;
return -ENOBUFS;
}
/**
* Concatenate I/O buffers into a single buffer
*
* @v list List of I/O buffers
* @ret iobuf Concatenated I/O buffer, or NULL on allocation failure
*
* After a successful concatenation, the list will be empty.
*/
struct io_buffer * iob_concatenate ( struct list_head *list ) {
struct io_buffer *iobuf;
struct io_buffer *tmp;
struct io_buffer *concatenated;
size_t len = 0;
/* If the list contains only a single entry, avoid an
* unnecessary additional allocation.
*/
if ( list_is_singular ( list ) ) {
iobuf = list_first_entry ( list, struct io_buffer, list );
INIT_LIST_HEAD ( list );
return iobuf;
}
/* Calculate total length */
list_for_each_entry ( iobuf, list, list )
len += iob_len ( iobuf );
/* Allocate new I/O buffer */
concatenated = alloc_iob_raw ( len, __alignof__ ( *iobuf ), 0 );
if ( ! concatenated )
return NULL;
/* Move data to new I/O buffer */
list_for_each_entry_safe ( iobuf, tmp, list, list ) {
list_del ( &iobuf->list );
memcpy ( iob_put ( concatenated, iob_len ( iobuf ) ),
iobuf->data, iob_len ( iobuf ) );
free_iob ( iobuf );
}
return concatenated;
}
/**
* Split I/O buffer
*
* @v iobuf I/O buffer
* @v len Length to split into a new I/O buffer
* @ret split New I/O buffer, or NULL on allocation failure
*
* Split the first @c len bytes of the existing I/O buffer into a
* separate I/O buffer. The resulting buffers are likely to have no
* headroom or tailroom.
*
* If this call fails, then the original buffer will be unmodified.
*/
struct io_buffer * iob_split ( struct io_buffer *iobuf, size_t len ) {
struct io_buffer *split;
/* Sanity checks */
assert ( len <= iob_len ( iobuf ) );
/* Allocate new I/O buffer */
split = alloc_iob ( len );
if ( ! split )
return NULL;
/* Copy in data */
memcpy ( iob_put ( split, len ), iobuf->data, len );
iob_pull ( iobuf, len );
return split;
}
