/*
 * Isochronous I/O functionality:
 *   - Isochronous DMA context management
 *   - Isochronous bus resource management (channels, bandwidth), client side
 *
 * Copyright (C) 2006 Kristian Hoegsberg <krh@bitplanet.net>
 *
 * 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_init(struct fw_iso_buffer *buffer, struct fw_card *card,
                       int page_count, enum dma_data_direction direction)
{
        int i, j;
        dma_addr_t address;

        buffer->page_count = page_count;
        buffer->direction = direction;

        buffer->pages = kmalloc(page_count * sizeof(buffer->pages[0]),
                                GFP_KERNEL);
        if (buffer->pages == NULL)
                goto out;

        for (i = 0; i < buffer->page_count; i++) {
                buffer->pages[i] = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
                if (buffer->pages[i] == NULL)
                        goto out_pages;

                address = dma_map_page(card->device, buffer->pages[i],
                                       0, PAGE_SIZE, direction);
                if (dma_mapping_error(card->device, address)) {
                        __free_page(buffer->pages[i]);
                        goto out_pages;
                }
                set_page_private(buffer->pages[i], address);
        }

        return 0;

 out_pages:
        for (j = 0; j < i; j++) {
                address = page_private(buffer->pages[j]);
                dma_unmap_page(card->device, address,
                               PAGE_SIZE, direction);
                __free_page(buffer->pages[j]);
        }
        kfree(buffer->pages);
 out:
        buffer->pages = NULL;

        return -ENOMEM;
}
EXPORT_SYMBOL(fw_iso_buffer_init);

int fw_iso_buffer_map(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; i++) {
                address = page_private(buffer->pages[i]);
                dma_unmap_page(card->device, address,
                               PAGE_SIZE, buffer->direction);
                __free_page(buffer->pages[i]);
        }

        kfree(buffer->pages);
        buffer->pages = NULL;
}
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)
{
        int 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_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);
}

/**
 * fw_iso_resource_manage() - Allocate or deallocate a channel and/or bandwidth
 *
 * In parameters: card, generation, channels_mask, bandwidth, allocate
 * Out parameters: channel, bandwidth
 * This function blocks (sleeps) during communication with the IRM.
 *
 * Allocates or deallocates at most one channel out of channels_mask.
 * channels_mask is a bitfield with MSB for channel 63 and LSB for channel 0.
 * (Note, the IRM's CHANNELS_AVAILABLE is a big-endian bitfield with MSB for
 * channel 0 and LSB for channel 63.)
 * Allocates or deallocates as many bandwidth allocation units as specified.
 *
 * Returns channel < 0 if no channel was allocated or deallocated.
 * Returns bandwidth = 0 if no bandwidth was allocated or deallocated.
 *
 * If generation is stale, deallocations succeed but allocations fail with
 * channel = -EAGAIN.
 *
 * If channel allocation fails, no bandwidth will be allocated either.
 * If bandwidth allocation fails, no channel will be allocated either.
 * But deallocations of channel and bandwidth are tried independently
 * of each other's success.
 */
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);