Viewing file:  dma.c (5.6 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/*
* linux/arch/arm/kernel/dma.c
*
* Copyright (C) 1995-2000 Russell King
*
* 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.
*
* Front-end to the DMA handling. This handles the allocation/freeing
* of DMA channels, and provides a unified interface to the machines
* DMA facilities.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mman.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <asm/dma.h>
#include <asm/mach/dma.h>
spinlock_t dma_spin_lock = SPIN_LOCK_UNLOCKED;
#if MAX_DMA_CHANNELS > 0
static dma_t dma_chan[MAX_DMA_CHANNELS];
/*
* Get dma list for /proc/dma
*/
int get_dma_list(char *buf)
{
dma_t *dma;
char *p = buf;
int i;
for (i = 0, dma = dma_chan; i < MAX_DMA_CHANNELS; i++, dma++)
if (dma->lock)
p += sprintf(p, "%2d: %14s %s\n", i,
dma->d_ops->type, dma->device_id);
return p - buf;
}
/*
* Request DMA channel
*
* On certain platforms, we have to allocate an interrupt as well...
*/
int request_dma(dmach_t channel, const char *device_id)
{
dma_t *dma = dma_chan + channel;
int ret;
if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
goto bad_dma;
if (xchg(&dma->lock, 1) != 0)
goto busy;
dma->device_id = device_id;
dma->active = 0;
dma->invalid = 1;
ret = 0;
if (dma->d_ops->request)
ret = dma->d_ops->request(channel, dma);
if (ret)
xchg(&dma->lock, 0);
return ret;
bad_dma:
printk(KERN_ERR "dma: trying to allocate DMA%d\n", channel);
return -EINVAL;
busy:
return -EBUSY;
}
/*
* Free DMA channel
*
* On certain platforms, we have to free interrupt as well...
*/
void free_dma(dmach_t channel)
{
dma_t *dma = dma_chan + channel;
if (channel >= MAX_DMA_CHANNELS || !dma->d_ops)
goto bad_dma;
if (dma->active) {
printk(KERN_ERR "dma%d: freeing active DMA\n", channel);
dma->d_ops->disable(channel, dma);
dma->active = 0;
}
if (xchg(&dma->lock, 0) != 0) {
if (dma->d_ops->free)
dma->d_ops->free(channel, dma);
return;
}
printk(KERN_ERR "dma%d: trying to free free DMA\n", channel);
return;
bad_dma:
printk(KERN_ERR "dma: trying to free DMA%d\n", channel);
}
/* Set DMA Scatter-Gather list
*/
void set_dma_sg (dmach_t channel, struct scatterlist *sg, int nr_sg)
{
dma_t *dma = dma_chan + channel;
dma->sg = sg;
dma->sgcount = nr_sg;
dma->using_sg = 1;
dma->invalid = 1;
}
/* Set DMA address
*
* Copy address to the structure, and set the invalid bit
*/
void set_dma_addr (dmach_t channel, unsigned long physaddr)
{
dma_t *dma = dma_chan + channel;
if (dma->active)
printk(KERN_ERR "dma%d: altering DMA address while "
"DMA active\n", channel);
dma->sg = &dma->buf;
dma->sgcount = 1;
dma->buf.address = bus_to_virt(physaddr);
dma->using_sg = 0;
dma->invalid = 1;
}
/* Set DMA byte count
*
* Copy address to the structure, and set the invalid bit
*/
void set_dma_count (dmach_t channel, unsigned long count)
{
dma_t *dma = dma_chan + channel;
if (dma->active)
printk(KERN_ERR "dma%d: altering DMA count while "
"DMA active\n", channel);
dma->sg = &dma->buf;
dma->sgcount = 1;
dma->buf.length = count;
dma->using_sg = 0;
dma->invalid = 1;
}
/* Set DMA direction mode
*/
void set_dma_mode (dmach_t channel, dmamode_t mode)
{
dma_t *dma = dma_chan + channel;
if (dma->active)
printk(KERN_ERR "dma%d: altering DMA mode while "
"DMA active\n", channel);
dma->dma_mode = mode;
dma->invalid = 1;
}
/* Enable DMA channel
*/
void enable_dma (dmach_t channel)
{
dma_t *dma = dma_chan + channel;
if (!dma->lock)
goto free_dma;
if (dma->active == 0) {
dma->active = 1;
dma->d_ops->enable(channel, dma);
}
return;
free_dma:
printk(KERN_ERR "dma%d: trying to enable free DMA\n", channel);
BUG();
}
/* Disable DMA channel
*/
void disable_dma (dmach_t channel)
{
dma_t *dma = dma_chan + channel;
if (!dma->lock)
goto free_dma;
if (dma->active == 1) {
dma->active = 0;
dma->d_ops->disable(channel, dma);
}
return;
free_dma:
printk(KERN_ERR "dma%d: trying to disable free DMA\n", channel);
BUG();
}
void set_dma_page(dmach_t channel, char pagenr)
{
printk(KERN_ERR "dma%d: trying to set_dma_page\n", channel);
}
void set_dma_speed(dmach_t channel, int cycle_ns)
{
dma_t *dma = dma_chan + channel;
int ret = 0;
if (dma->d_ops->setspeed)
ret = dma->d_ops->setspeed(channel, dma, cycle_ns);
dma->speed = ret;
}
int get_dma_residue(dmach_t channel)
{
dma_t *dma = dma_chan + channel;
int ret = 0;
if (dma->d_ops->residue)
ret = dma->d_ops->residue(channel, dma);
return ret;
}
void __init init_dma(void)
{
arch_dma_init(dma_chan);
}
#else
int request_dma(dmach_t channel, const char *device_id)
{
return -EINVAL;
}
int get_dma_residue(dmach_t channel)
{
return 0;
}
#define GLOBAL_ALIAS(_a,_b) asm (".set " #_a "," #_b "; .globl " #_a)
GLOBAL_ALIAS(disable_dma, get_dma_residue);
GLOBAL_ALIAS(enable_dma, get_dma_residue);
GLOBAL_ALIAS(free_dma, get_dma_residue);
GLOBAL_ALIAS(get_dma_list, get_dma_residue);
GLOBAL_ALIAS(set_dma_mode, get_dma_residue);
GLOBAL_ALIAS(set_dma_page, get_dma_residue);
GLOBAL_ALIAS(set_dma_count, get_dma_residue);
GLOBAL_ALIAS(set_dma_addr, get_dma_residue);
GLOBAL_ALIAS(set_dma_sg, get_dma_residue);
GLOBAL_ALIAS(set_dma_speed, get_dma_residue);
GLOBAL_ALIAS(init_dma, get_dma_residue);
#endif
EXPORT_SYMBOL(enable_dma);
EXPORT_SYMBOL(disable_dma);
EXPORT_SYMBOL(set_dma_addr);
EXPORT_SYMBOL(set_dma_count);
EXPORT_SYMBOL(set_dma_mode);
EXPORT_SYMBOL(set_dma_page);
EXPORT_SYMBOL(get_dma_residue);
EXPORT_SYMBOL(set_dma_sg);
EXPORT_SYMBOL(set_dma_speed);
|