Logo Search packages:      
Sourcecode: linux version File versions  Download package

dma-api.c

/*
 * arch/sh/drivers/dma/dma-api.c
 *
 * SuperH-specific DMA management API
 *
 * Copyright (C) 2003, 2004, 2005  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <asm/dma.h>

DEFINE_SPINLOCK(dma_spin_lock);
static LIST_HEAD(registered_dmac_list);

struct dma_info *get_dma_info(unsigned int chan)
{
      struct dma_info *info;

      /*
       * Look for each DMAC's range to determine who the owner of
       * the channel is.
       */
      list_for_each_entry(info, &registered_dmac_list, list) {
            if ((chan <  info->first_vchannel_nr) ||
                (chan >= info->first_vchannel_nr + info->nr_channels))
                  continue;

            return info;
      }

      return NULL;
}
EXPORT_SYMBOL(get_dma_info);

struct dma_info *get_dma_info_by_name(const char *dmac_name)
{
      struct dma_info *info;

      list_for_each_entry(info, &registered_dmac_list, list) {
            if (dmac_name && (strcmp(dmac_name, info->name) != 0))
                  continue;
            else
                  return info;
      }

      return NULL;
}
EXPORT_SYMBOL(get_dma_info_by_name);

static unsigned int get_nr_channels(void)
{
      struct dma_info *info;
      unsigned int nr = 0;

      if (unlikely(list_empty(&registered_dmac_list)))
            return nr;

      list_for_each_entry(info, &registered_dmac_list, list)
            nr += info->nr_channels;

      return nr;
}

struct dma_channel *get_dma_channel(unsigned int chan)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel;
      int i;

      if (unlikely(!info))
            return ERR_PTR(-EINVAL);

      for (i = 0; i < info->nr_channels; i++) {
            channel = &info->channels[i];
            if (channel->vchan == chan)
                  return channel;
      }

      return NULL;
}
EXPORT_SYMBOL(get_dma_channel);

int get_dma_residue(unsigned int chan)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel = get_dma_channel(chan);

      if (info->ops->get_residue)
            return info->ops->get_residue(channel);

      return 0;
}
EXPORT_SYMBOL(get_dma_residue);

static int search_cap(const char **haystack, const char *needle)
{
      const char **p;

      for (p = haystack; *p; p++)
            if (strcmp(*p, needle) == 0)
                  return 1;

      return 0;
}

/**
 * request_dma_bycap - Allocate a DMA channel based on its capabilities
 * @dmac: List of DMA controllers to search
 * @caps: List of capabilities
 *
 * Search all channels of all DMA controllers to find a channel which
 * matches the requested capabilities. The result is the channel
 * number if a match is found, or %-ENODEV if no match is found.
 *
 * Note that not all DMA controllers export capabilities, in which
 * case they can never be allocated using this API, and so
 * request_dma() must be used specifying the channel number.
 */
int request_dma_bycap(const char **dmac, const char **caps, const char *dev_id)
{
      unsigned int found = 0;
      struct dma_info *info;
      const char **p;
      int i;

      BUG_ON(!dmac || !caps);

      list_for_each_entry(info, &registered_dmac_list, list)
            if (strcmp(*dmac, info->name) == 0) {
                  found = 1;
                  break;
            }

      if (!found)
            return -ENODEV;

      for (i = 0; i < info->nr_channels; i++) {
            struct dma_channel *channel = &info->channels[i];

            if (unlikely(!channel->caps))
                  continue;

            for (p = caps; *p; p++) {
                  if (!search_cap(channel->caps, *p))
                        break;
                  if (request_dma(channel->chan, dev_id) == 0)
                        return channel->chan;
            }
      }

      return -EINVAL;
}
EXPORT_SYMBOL(request_dma_bycap);

int dmac_search_free_channel(const char *dev_id)
{
      struct dma_channel *channel = { 0 };
      struct dma_info *info = get_dma_info(0);
      int i;

      for (i = 0; i < info->nr_channels; i++) {
            channel = &info->channels[i];
            if (unlikely(!channel))
                  return -ENODEV;

            if (atomic_read(&channel->busy) == 0)
                  break;
      }

      if (info->ops->request) {
            int result = info->ops->request(channel);
            if (result)
                  return result;

            atomic_set(&channel->busy, 1);
            return channel->chan;
      }

      return -ENOSYS;
}

int request_dma(unsigned int chan, const char *dev_id)
{
      struct dma_channel *channel = { 0 };
      struct dma_info *info = get_dma_info(chan);
      int result;

      channel = get_dma_channel(chan);
      if (atomic_xchg(&channel->busy, 1))
            return -EBUSY;

      strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id));

      if (info->ops->request) {
            result = info->ops->request(channel);
            if (result)
                  atomic_set(&channel->busy, 0);

            return result;
      }

      return 0;
}
EXPORT_SYMBOL(request_dma);

void free_dma(unsigned int chan)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel = get_dma_channel(chan);

      if (info->ops->free)
            info->ops->free(channel);

      atomic_set(&channel->busy, 0);
}
EXPORT_SYMBOL(free_dma);

void dma_wait_for_completion(unsigned int chan)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel = get_dma_channel(chan);

      if (channel->flags & DMA_TEI_CAPABLE) {
            wait_event(channel->wait_queue,
                     (info->ops->get_residue(channel) == 0));
            return;
      }

      while (info->ops->get_residue(channel))
            cpu_relax();
}
EXPORT_SYMBOL(dma_wait_for_completion);

int register_chan_caps(const char *dmac, struct dma_chan_caps *caps)
{
      struct dma_info *info;
      unsigned int found = 0;
      int i;

      list_for_each_entry(info, &registered_dmac_list, list)
            if (strcmp(dmac, info->name) == 0) {
                  found = 1;
                  break;
            }

      if (unlikely(!found))
            return -ENODEV;

      for (i = 0; i < info->nr_channels; i++, caps++) {
            struct dma_channel *channel;

            if ((info->first_channel_nr + i) != caps->ch_num)
                  return -EINVAL;

            channel = &info->channels[i];
            channel->caps = caps->caplist;
      }

      return 0;
}
EXPORT_SYMBOL(register_chan_caps);

void dma_configure_channel(unsigned int chan, unsigned long flags)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel = get_dma_channel(chan);

      if (info->ops->configure)
            info->ops->configure(channel, flags);
}
EXPORT_SYMBOL(dma_configure_channel);

int dma_xfer(unsigned int chan, unsigned long from,
           unsigned long to, size_t size, unsigned int mode)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel = get_dma_channel(chan);

      channel->sar      = from;
      channel->dar      = to;
      channel->count    = size;
      channel->mode     = mode;

      return info->ops->xfer(channel);
}
EXPORT_SYMBOL(dma_xfer);

int dma_extend(unsigned int chan, unsigned long op, void *param)
{
      struct dma_info *info = get_dma_info(chan);
      struct dma_channel *channel = get_dma_channel(chan);

      if (info->ops->extend)
            return info->ops->extend(channel, op, param);

      return -ENOSYS;
}
EXPORT_SYMBOL(dma_extend);

static int dma_read_proc(char *buf, char **start, off_t off,
                   int len, int *eof, void *data)
{
      struct dma_info *info;
      char *p = buf;

      if (list_empty(&registered_dmac_list))
            return 0;

      /*
       * Iterate over each registered DMAC
       */
      list_for_each_entry(info, &registered_dmac_list, list) {
            int i;

            /*
             * Iterate over each channel
             */
            for (i = 0; i < info->nr_channels; i++) {
                  struct dma_channel *channel = info->channels + i;

                  if (!(channel->flags & DMA_CONFIGURED))
                        continue;

                  p += sprintf(p, "%2d: %14s    %s\n", i,
                             info->name, channel->dev_id);
            }
      }

      return p - buf;
}

int register_dmac(struct dma_info *info)
{
      unsigned int total_channels, i;

      INIT_LIST_HEAD(&info->list);

      printk(KERN_INFO "DMA: Registering %s handler (%d channel%s).\n",
             info->name, info->nr_channels, info->nr_channels > 1 ? "s" : "");

      BUG_ON((info->flags & DMAC_CHANNELS_CONFIGURED) && !info->channels);

      info->pdev = platform_device_register_simple((char *)info->name, -1,
                                         NULL, 0);
      if (IS_ERR(info->pdev))
            return PTR_ERR(info->pdev);

      /*
       * Don't touch pre-configured channels
       */
      if (!(info->flags & DMAC_CHANNELS_CONFIGURED)) {
            unsigned int size;

            size = sizeof(struct dma_channel) * info->nr_channels;

            info->channels = kzalloc(size, GFP_KERNEL);
            if (!info->channels)
                  return -ENOMEM;
      }

      total_channels = get_nr_channels();
      info->first_vchannel_nr = total_channels;
      for (i = 0; i < info->nr_channels; i++) {
            struct dma_channel *chan = &info->channels[i];

            atomic_set(&chan->busy, 0);

            chan->chan  = info->first_channel_nr + i;
            chan->vchan = info->first_channel_nr + i + total_channels;

            memcpy(chan->dev_id, "Unused", 7);

            if (info->flags & DMAC_CHANNELS_TEI_CAPABLE)
                  chan->flags |= DMA_TEI_CAPABLE;

            init_waitqueue_head(&chan->wait_queue);
            dma_create_sysfs_files(chan, info);
      }

      list_add(&info->list, &registered_dmac_list);

      return 0;
}
EXPORT_SYMBOL(register_dmac);

void unregister_dmac(struct dma_info *info)
{
      unsigned int i;

      for (i = 0; i < info->nr_channels; i++)
            dma_remove_sysfs_files(info->channels + i, info);

      if (!(info->flags & DMAC_CHANNELS_CONFIGURED))
            kfree(info->channels);

      list_del(&info->list);
      platform_device_unregister(info->pdev);
}
EXPORT_SYMBOL(unregister_dmac);

static int __init dma_api_init(void)
{
      printk(KERN_NOTICE "DMA: Registering DMA API.\n");
      create_proc_read_entry("dma", 0, 0, dma_read_proc, 0);
      return 0;
}
subsys_initcall(dma_api_init);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("DMA API for SuperH");
MODULE_LICENSE("GPL");

Generated by  Doxygen 1.6.0   Back to index