dma-api.c

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/*
 * 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 <linux/slab.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;
}

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(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");
    return create_proc_read_entry("dma", 0, 0, dma_read_proc, 0)
            ? 0 : -ENOMEM;
}
subsys_initcall(dma_api_init);

MODULE_AUTHOR("Paul Mundt <[email protected]>");
MODULE_DESCRIPTION("DMA API for SuperH");
MODULE_LICENSE("GPL");