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dma.c

/*
 *  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/init.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/scatterlist.h>

#include <asm/dma.h>

#include <asm/mach/dma.h>

DEFINE_SPINLOCK(dma_spin_lock);
EXPORT_SYMBOL(dma_spin_lock);

static dma_t *dma_chan[MAX_DMA_CHANNELS];

static inline dma_t *dma_channel(unsigned int chan)
{
      if (chan >= MAX_DMA_CHANNELS)
            return NULL;

      return dma_chan[chan];
}

int __init isa_dma_add(unsigned int chan, dma_t *dma)
{
      if (!dma->d_ops)
            return -EINVAL;

      sg_init_table(&dma->buf, 1);

      if (dma_chan[chan])
            return -EBUSY;
      dma_chan[chan] = dma;
      return 0;
}

/*
 * Request DMA channel
 *
 * On certain platforms, we have to allocate an interrupt as well...
 */
int request_dma(unsigned int chan, const char *device_id)
{
      dma_t *dma = dma_channel(chan);
      int ret;

      if (!dma)
            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(chan, dma);

      if (ret)
            xchg(&dma->lock, 0);

      return ret;

bad_dma:
      printk(KERN_ERR "dma: trying to allocate DMA%d\n", chan);
      return -EINVAL;

busy:
      return -EBUSY;
}
EXPORT_SYMBOL(request_dma);

/*
 * Free DMA channel
 *
 * On certain platforms, we have to free interrupt as well...
 */
void free_dma(unsigned int chan)
{
      dma_t *dma = dma_channel(chan);

      if (!dma)
            goto bad_dma;

      if (dma->active) {
            printk(KERN_ERR "dma%d: freeing active DMA\n", chan);
            dma->d_ops->disable(chan, dma);
            dma->active = 0;
      }

      if (xchg(&dma->lock, 0) != 0) {
            if (dma->d_ops->free)
                  dma->d_ops->free(chan, dma);
            return;
      }

      printk(KERN_ERR "dma%d: trying to free free DMA\n", chan);
      return;

bad_dma:
      printk(KERN_ERR "dma: trying to free DMA%d\n", chan);
}
EXPORT_SYMBOL(free_dma);

/* Set DMA Scatter-Gather list
 */
void set_dma_sg (unsigned int chan, struct scatterlist *sg, int nr_sg)
{
      dma_t *dma = dma_channel(chan);

      if (dma->active)
            printk(KERN_ERR "dma%d: altering DMA SG while "
                   "DMA active\n", chan);

      dma->sg = sg;
      dma->sgcount = nr_sg;
      dma->invalid = 1;
}
EXPORT_SYMBOL(set_dma_sg);

/* Set DMA address
 *
 * Copy address to the structure, and set the invalid bit
 */
void __set_dma_addr (unsigned int chan, void *addr)
{
      dma_t *dma = dma_channel(chan);

      if (dma->active)
            printk(KERN_ERR "dma%d: altering DMA address while "
                   "DMA active\n", chan);

      dma->sg = NULL;
      dma->addr = addr;
      dma->invalid = 1;
}
EXPORT_SYMBOL(__set_dma_addr);

/* Set DMA byte count
 *
 * Copy address to the structure, and set the invalid bit
 */
void set_dma_count (unsigned int chan, unsigned long count)
{
      dma_t *dma = dma_channel(chan);

      if (dma->active)
            printk(KERN_ERR "dma%d: altering DMA count while "
                   "DMA active\n", chan);

      dma->sg = NULL;
      dma->count = count;
      dma->invalid = 1;
}
EXPORT_SYMBOL(set_dma_count);

/* Set DMA direction mode
 */
void set_dma_mode (unsigned int chan, unsigned int mode)
{
      dma_t *dma = dma_channel(chan);

      if (dma->active)
            printk(KERN_ERR "dma%d: altering DMA mode while "
                   "DMA active\n", chan);

      dma->dma_mode = mode;
      dma->invalid = 1;
}
EXPORT_SYMBOL(set_dma_mode);

/* Enable DMA channel
 */
void enable_dma (unsigned int chan)
{
      dma_t *dma = dma_channel(chan);

      if (!dma->lock)
            goto free_dma;

      if (dma->active == 0) {
            dma->active = 1;
            dma->d_ops->enable(chan, dma);
      }
      return;

free_dma:
      printk(KERN_ERR "dma%d: trying to enable free DMA\n", chan);
      BUG();
}
EXPORT_SYMBOL(enable_dma);

/* Disable DMA channel
 */
void disable_dma (unsigned int chan)
{
      dma_t *dma = dma_channel(chan);

      if (!dma->lock)
            goto free_dma;

      if (dma->active == 1) {
            dma->active = 0;
            dma->d_ops->disable(chan, dma);
      }
      return;

free_dma:
      printk(KERN_ERR "dma%d: trying to disable free DMA\n", chan);
      BUG();
}
EXPORT_SYMBOL(disable_dma);

/*
 * Is the specified DMA channel active?
 */
int dma_channel_active(unsigned int chan)
{
      dma_t *dma = dma_channel(chan);
      return dma->active;
}
EXPORT_SYMBOL(dma_channel_active);

void set_dma_page(unsigned int chan, char pagenr)
{
      printk(KERN_ERR "dma%d: trying to set_dma_page\n", chan);
}
EXPORT_SYMBOL(set_dma_page);

void set_dma_speed(unsigned int chan, int cycle_ns)
{
      dma_t *dma = dma_channel(chan);
      int ret = 0;

      if (dma->d_ops->setspeed)
            ret = dma->d_ops->setspeed(chan, dma, cycle_ns);
      dma->speed = ret;
}
EXPORT_SYMBOL(set_dma_speed);

int get_dma_residue(unsigned int chan)
{
      dma_t *dma = dma_channel(chan);
      int ret = 0;

      if (dma->d_ops->residue)
            ret = dma->d_ops->residue(chan, dma);

      return ret;
}
EXPORT_SYMBOL(get_dma_residue);

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