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/* -*- linux-c -*-
*
* drivers/fims/dma.c
*
* Copyright (C) 2008 by Digi International Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* !Revision: $Revision: 1.3 $
* !Author: Luis Galdos
* !Descr:
* !References:
*/
#ifndef __FIM_API_DMA_H
#define __FIM_API_DMA_H
#include <linux/module.h>
#include <linux/errno.h>
#include <mach/dma-ns921x.h>
/*
* The access to the DMA-channels of the FIMs is only provided by the FIM-API
* The FIM-drivers should not use the functions of this source code file
*/
inline static void fim_dma_reset_fifo(struct iohub_dma_fifo_t *fifo)
{
if (!fifo)
return;
fifo->next_free = fifo->first;
fifo->dma_first = fifo->first;
fifo->dma_last = fifo->dma_next = NULL;
}
inline int fim_dma_init_fifo(struct iohub_dma_fifo_t *fifo, int length,
struct iohub_dma_desc_t **descs)
{
if (!fifo || !length || !descs)
return -EINVAL;
/* @XXX: These are the start values for the API */
fifo->length = length;
fifo->first = (struct iohub_dma_desc_t *)descs;
fifo->last = fifo->first + fifo->length - 1;
fifo->next_free = fifo->first;
fifo->dma_first = fifo->first;
fifo->dma_last = fifo->dma_next = NULL;
return 0;
}
inline static struct iohub_dma_desc_t *fim_dma_get_next(struct iohub_dma_fifo_t *fifo,
struct iohub_dma_desc_t *ptr)
{
if (ptr == fifo->last)
return fifo->first;
else
return ptr + 1;
}
/*
* Return the index of a passed DMA-descriptor
*/
inline static struct iohub_dma_desc_t *fim_dma_get_by_index(struct iohub_dma_fifo_t *fifo,
int index)
{
if (index < 0)
return fifo->first;
else if (index >= fifo->length)
return fifo->last;
else
return fifo->first + index;
}
inline static int fim_dma_length(struct iohub_dma_fifo_t *fifo)
{
return fifo->length;
}
/*
* Returns the number of free DMA-descriptors
*/
inline static int fim_dma_frees(struct iohub_dma_fifo_t *fifo)
{
int retval;
/* The first is the INIT state of the FIFO */
if (!fifo->dma_last && !fifo->dma_next)
retval = fifo->length;
else if (fifo->dma_last == fifo->dma_next)
retval = fifo->length;
else if (!fifo->dma_last)
retval = fifo->last - fifo->dma_next;
else if (fifo->dma_next == fifo->dma_first)
retval = (fifo->last - fifo->first);
else if (fifo->dma_next > fifo->dma_first)
retval = (fifo->last - fifo->dma_next) +
(fifo->dma_first - fifo->first);
else
retval = (fifo->dma_first - fifo->dma_next);
return retval;
}
/*
* Check if the FIFO contains descriptors or is empty
*/
inline static int fim_dma_is_empty(struct iohub_dma_fifo_t *fifo)
{
/* @XXX: That's only for FIFOs with one pointer */
if (fifo->length == 1 && fifo->dma_next)
return 0;
if (fim_dma_frees(fifo) == fifo->length)
return 1;
else
return 0;
}
inline static int fim_dma_get_index(struct iohub_dma_fifo_t *fifo,
struct iohub_dma_desc_t *desc)
{
return desc - fifo->first;
}
/*
* Check if there is enough space for a specific number of buffer descriptors.
* Return a pointer to the first buffer descriptor is the FIFO has enough space
*/
inline static struct iohub_dma_desc_t *fim_dma_alloc(struct iohub_dma_fifo_t *fifo,
int count)
{
int len, diff;
struct iohub_dma_desc_t *tmp, *retval;
len = fim_dma_frees(fifo);
if (len < count)
return NULL;
if (!fifo->dma_next) {
retval = fifo->first;
fifo->dma_next = fifo->first + count - 1;
} else {
retval = fim_dma_get_next(fifo, fifo->dma_next);
tmp = fifo->dma_next + count;
if (tmp <= fifo->last)
fifo->dma_next = tmp;
else {
diff = tmp - fifo->last - 1;
fifo->dma_next = fifo->first + diff;
}
}
return retval;
}
#endif /* ifndef __FIM_API_DMA_H */
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