core-iso.c

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/*
 * Isochronous I/O functionality:
 *   - Isochronous DMA context management
 *   - Isochronous bus resource management (channels, bandwidth), client side
 *
 * Copyright (C) 2006 Kristian Hoegsberg <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/export.h>

#include <asm/byteorder.h>

#include "core.h"

/*
 * Isochronous DMA context management
 */

int fw_iso_buffer_alloc(struct fw_iso_buffer *buffer, int page_count)
{
    int i;

    buffer->page_count = 0;
    buffer->page_count_mapped = 0;
    buffer->pages = kmalloc(page_count * sizeof(buffer->pages[0]),
                GFP_KERNEL);
    if (buffer->pages == NULL)
        return -ENOMEM;

    for (i = 0; i < page_count; i++) {
        buffer->pages[i] = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
        if (buffer->pages[i] == NULL)
            break;
    }
    buffer->page_count = i;
    if (i < page_count) {
        fw_iso_buffer_destroy(buffer, NULL);
        return -ENOMEM;
    }

    return 0;
}

int fw_iso_buffer_map_dma(struct fw_iso_buffer *buffer, struct fw_card *card,
              enum dma_data_direction direction)
{
    dma_addr_t address;
    int i;

    buffer->direction = direction;

    for (i = 0; i < buffer->page_count; i++) {
        address = dma_map_page(card->device, buffer->pages[i],
                       0, PAGE_SIZE, direction);
        if (dma_mapping_error(card->device, address))
            break;

        set_page_private(buffer->pages[i], address);
    }
    buffer->page_count_mapped = i;
    if (i < buffer->page_count)
        return -ENOMEM;

    return 0;
}

int fw_iso_buffer_init(struct fw_iso_buffer *buffer, struct fw_card *card,
               int page_count, enum dma_data_direction direction)
{
    int ret;

    ret = fw_iso_buffer_alloc(buffer, page_count);
    if (ret < 0)
        return ret;

    ret = fw_iso_buffer_map_dma(buffer, card, direction);
    if (ret < 0)
        fw_iso_buffer_destroy(buffer, card);

    return ret;
}
EXPORT_SYMBOL(fw_iso_buffer_init);

int fw_iso_buffer_map_vma(struct fw_iso_buffer *buffer,
              struct vm_area_struct *vma)
{
    unsigned long uaddr;
    int i, err;

    uaddr = vma->vm_start;
    for (i = 0; i < buffer->page_count; i++) {
        err = vm_insert_page(vma, uaddr, buffer->pages[i]);
        if (err)
            return err;

        uaddr += PAGE_SIZE;
    }

    return 0;
}

void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer,
               struct fw_card *card)
{
    int i;
    dma_addr_t address;

    for (i = 0; i < buffer->page_count_mapped; i++) {
        address = page_private(buffer->pages[i]);
        dma_unmap_page(card->device, address,
                   PAGE_SIZE, buffer->direction);
    }
    for (i = 0; i < buffer->page_count; i++)
        __free_page(buffer->pages[i]);

    kfree(buffer->pages);
    buffer->pages = NULL;
    buffer->page_count = 0;
    buffer->page_count_mapped = 0;
}
EXPORT_SYMBOL(fw_iso_buffer_destroy);

/* Convert DMA address to offset into virtually contiguous buffer. */
size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)
{
    size_t i;
    dma_addr_t address;
    ssize_t offset;

    for (i = 0; i < buffer->page_count; i++) {
        address = page_private(buffer->pages[i]);
        offset = (ssize_t)completed - (ssize_t)address;
        if (offset > 0 && offset <= PAGE_SIZE)
            return (i << PAGE_SHIFT) + offset;
    }

    return 0;
}

struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
        int type, int channel, int speed, size_t header_size,
        fw_iso_callback_t callback, void *callback_data)
{
    struct fw_iso_context *ctx;

    ctx = card->driver->allocate_iso_context(card,
                         type, channel, header_size);
    if (IS_ERR(ctx))
        return ctx;

    ctx->card = card;
    ctx->type = type;
    ctx->channel = channel;
    ctx->speed = speed;
    ctx->header_size = header_size;
    ctx->callback.sc = callback;
    ctx->callback_data = callback_data;

    return ctx;
}
EXPORT_SYMBOL(fw_iso_context_create);

void fw_iso_context_destroy(struct fw_iso_context *ctx)
{
    ctx->card->driver->free_iso_context(ctx);
}
EXPORT_SYMBOL(fw_iso_context_destroy);

int fw_iso_context_start(struct fw_iso_context *ctx,
             int cycle, int sync, int tags)
{
    return ctx->card->driver->start_iso(ctx, cycle, sync, tags);
}
EXPORT_SYMBOL(fw_iso_context_start);

int fw_iso_context_set_channels(struct fw_iso_context *ctx, u64 *channels)
{
    return ctx->card->driver->set_iso_channels(ctx, channels);
}

int fw_iso_context_queue(struct fw_iso_context *ctx,
             struct fw_iso_packet *packet,
             struct fw_iso_buffer *buffer,
             unsigned long payload)
{
    return ctx->card->driver->queue_iso(ctx, packet, buffer, payload);
}
EXPORT_SYMBOL(fw_iso_context_queue);

void fw_iso_context_queue_flush(struct fw_iso_context *ctx)
{
    ctx->card->driver->flush_queue_iso(ctx);
}
EXPORT_SYMBOL(fw_iso_context_queue_flush);

int fw_iso_context_flush_completions(struct fw_iso_context *ctx)
{
    return ctx->card->driver->flush_iso_completions(ctx);
}
EXPORT_SYMBOL(fw_iso_context_flush_completions);

int fw_iso_context_stop(struct fw_iso_context *ctx)
{
    return ctx->card->driver->stop_iso(ctx);
}
EXPORT_SYMBOL(fw_iso_context_stop);

/*
 * Isochronous bus resource management (channels, bandwidth), client side
 */

static int manage_bandwidth(struct fw_card *card, int irm_id, int generation,
                int bandwidth, bool allocate)
{
    int try, new, old = allocate ? BANDWIDTH_AVAILABLE_INITIAL : 0;
    __be32 data[2];

    /*
     * On a 1394a IRM with low contention, try < 1 is enough.
     * On a 1394-1995 IRM, we need at least try < 2.
     * Let's just do try < 5.
     */
    for (try = 0; try < 5; try++) {
        new = allocate ? old - bandwidth : old + bandwidth;
        if (new < 0 || new > BANDWIDTH_AVAILABLE_INITIAL)
            return -EBUSY;

        data[0] = cpu_to_be32(old);
        data[1] = cpu_to_be32(new);
        switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
                irm_id, generation, SCODE_100,
                CSR_REGISTER_BASE + CSR_BANDWIDTH_AVAILABLE,
                data, 8)) {
        case RCODE_GENERATION:
            /* A generation change frees all bandwidth. */
            return allocate ? -EAGAIN : bandwidth;

        case RCODE_COMPLETE:
            if (be32_to_cpup(data) == old)
                return bandwidth;

            old = be32_to_cpup(data);
            /* Fall through. */
        }
    }

    return -EIO;
}

static int manage_channel(struct fw_card *card, int irm_id, int generation,
        u32 channels_mask, u64 offset, bool allocate)
{
    __be32 bit, all, old;
    __be32 data[2];
    int channel, ret = -EIO, retry = 5;

    old = all = allocate ? cpu_to_be32(~0) : 0;

    for (channel = 0; channel < 32; channel++) {
        if (!(channels_mask & 1 << channel))
            continue;

        ret = -EBUSY;

        bit = cpu_to_be32(1 << (31 - channel));
        if ((old & bit) != (all & bit))
            continue;

        data[0] = old;
        data[1] = old ^ bit;
        switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
                       irm_id, generation, SCODE_100,
                       offset, data, 8)) {
        case RCODE_GENERATION:
            /* A generation change frees all channels. */
            return allocate ? -EAGAIN : channel;

        case RCODE_COMPLETE:
            if (data[0] == old)
                return channel;

            old = data[0];

            /* Is the IRM 1394a-2000 compliant? */
            if ((data[0] & bit) == (data[1] & bit))
                continue;

            /* 1394-1995 IRM, fall through to retry. */
        default:
            if (retry) {
                retry--;
                channel--;
            } else {
                ret = -EIO;
            }
        }
    }

    return ret;
}

static void deallocate_channel(struct fw_card *card, int irm_id,
                   int generation, int channel)
{
    u32 mask;
    u64 offset;

    mask = channel < 32 ? 1 << channel : 1 << (channel - 32);
    offset = channel < 32 ? CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI :
                CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO;

    manage_channel(card, irm_id, generation, mask, offset, false);
}

void fw_iso_resource_manage(struct fw_card *card, int generation,
                u64 channels_mask, int *channel, int *bandwidth,
                bool allocate)
{
    u32 channels_hi = channels_mask;    /* channels 31...0 */
    u32 channels_lo = channels_mask >> 32;  /* channels 63...32 */
    int irm_id, ret, c = -EINVAL;

    spin_lock_irq(&card->lock);
    irm_id = card->irm_node->node_id;
    spin_unlock_irq(&card->lock);

    if (channels_hi)
        c = manage_channel(card, irm_id, generation, channels_hi,
                CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI,
                allocate);
    if (channels_lo && c < 0) {
        c = manage_channel(card, irm_id, generation, channels_lo,
                CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO,
                allocate);
        if (c >= 0)
            c += 32;
    }
    *channel = c;

    if (allocate && channels_mask != 0 && c < 0)
        *bandwidth = 0;

    if (*bandwidth == 0)
        return;

    ret = manage_bandwidth(card, irm_id, generation, *bandwidth, allocate);
    if (ret < 0)
        *bandwidth = 0;

    if (allocate && ret < 0) {
        if (c >= 0)
            deallocate_channel(card, irm_id, generation, c);
        *channel = ret;
    }
}
EXPORT_SYMBOL(fw_iso_resource_manage);