firewire: Implement functionality to stop isochronous DMA contexts.

[safe/jmp/linux-2.6] / drivers / firewire / fw-ohci.c

/*                                              -*- c-basic-offset: 8 -*-
 *
 * fw-ohci.c - Driver for OHCI 1394 boards
 * Copyright (C) 2003-2006 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/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/dma-mapping.h>

#include <asm/uaccess.h>
#include <asm/semaphore.h>

#include "fw-transaction.h"
#include "fw-ohci.h"

#define descriptor_output_more          0
#define descriptor_output_last          (1 << 12)
#define descriptor_input_more           (2 << 12)
#define descriptor_input_last           (3 << 12)
#define descriptor_status               (1 << 11)
#define descriptor_key_immediate        (2 << 8)
#define descriptor_ping                 (1 << 7)
#define descriptor_yy                   (1 << 6)
#define descriptor_no_irq               (0 << 4)
#define descriptor_irq_error            (1 << 4)
#define descriptor_irq_always           (3 << 4)
#define descriptor_branch_always        (3 << 2)
#define descriptor_wait                 (3 << 0)

struct descriptor {
        __le16 req_count;
        __le16 control;
        __le32 data_address;
        __le32 branch_address;
        __le16 res_count;
        __le16 transfer_status;
} __attribute__((aligned(16)));

struct db_descriptor {
        __le16 first_size;
        __le16 control;
        __le16 second_req_count;
        __le16 first_req_count;
        __le32 branch_address;
        __le16 second_res_count;
        __le16 first_res_count;
        __le32 reserved0;
        __le32 first_buffer;
        __le32 second_buffer;
        __le32 reserved1;
} __attribute__((aligned(16)));

#define control_set(regs)       (regs)
#define control_clear(regs)     ((regs) + 4)
#define command_ptr(regs)       ((regs) + 12)
#define context_match(regs)     ((regs) + 16)

struct ar_buffer {
        struct descriptor descriptor;
        struct ar_buffer *next;
        __le32 data[0];
};

struct ar_context {
        struct fw_ohci *ohci;
        struct ar_buffer *current_buffer;
        struct ar_buffer *last_buffer;
        void *pointer;
        u32 regs;
        struct tasklet_struct tasklet;
};

struct context;

typedef int (*descriptor_callback_t)(struct context *ctx,
                                     struct descriptor *d,
                                     struct descriptor *last);
struct context {
        struct fw_ohci *ohci;
        u32 regs;
 
        struct descriptor *buffer;
        dma_addr_t buffer_bus;
        size_t buffer_size;
        struct descriptor *head_descriptor;
        struct descriptor *tail_descriptor;
        struct descriptor *tail_descriptor_last;
        struct descriptor *prev_descriptor;

        descriptor_callback_t callback;

        struct tasklet_struct tasklet;
};
 


struct at_context {
        struct fw_ohci *ohci;
        dma_addr_t descriptor_bus;
        dma_addr_t buffer_bus;
        struct fw_packet *current_packet;

        struct list_head list;

        struct {
                struct descriptor more;
                __le32 header[4];
                struct descriptor last;
        } d;

        u32 regs;

        struct tasklet_struct tasklet;
};

#define it_header_sy(v)          ((v) <<  0)
#define it_header_tcode(v)       ((v) <<  4)
#define it_header_channel(v)     ((v) <<  8)
#define it_header_tag(v)         ((v) << 14)
#define it_header_speed(v)       ((v) << 16)
#define it_header_data_length(v) ((v) << 16)

struct iso_context {
        struct fw_iso_context base;
        struct context context;
};

#define CONFIG_ROM_SIZE 1024

struct fw_ohci {
        struct fw_card card;

        __iomem char *registers;
        dma_addr_t self_id_bus;
        __le32 *self_id_cpu;
        struct tasklet_struct bus_reset_tasklet;
        int node_id;
        int generation;
        int request_generation;

        /* Spinlock for accessing fw_ohci data.  Never call out of
         * this driver with this lock held. */
        spinlock_t lock;
        u32 self_id_buffer[512];

        /* Config rom buffers */
        __be32 *config_rom;
        dma_addr_t config_rom_bus;
        __be32 *next_config_rom;
        dma_addr_t next_config_rom_bus;
        u32 next_header;

        struct ar_context ar_request_ctx;
        struct ar_context ar_response_ctx;
        struct at_context at_request_ctx;
        struct at_context at_response_ctx;

        u32 it_context_mask;
        struct iso_context *it_context_list;
        u32 ir_context_mask;
        struct iso_context *ir_context_list;
};

static inline struct fw_ohci *fw_ohci(struct fw_card *card)
{
        return container_of(card, struct fw_ohci, card);
}

#define IT_CONTEXT_CYCLE_MATCH_ENABLE   0x80000000
#define IR_CONTEXT_BUFFER_FILL          0x80000000
#define IR_CONTEXT_ISOCH_HEADER         0x40000000
#define IR_CONTEXT_CYCLE_MATCH_ENABLE   0x20000000
#define IR_CONTEXT_MULTI_CHANNEL_MODE   0x10000000
#define IR_CONTEXT_DUAL_BUFFER_MODE     0x08000000

#define CONTEXT_RUN     0x8000
#define CONTEXT_WAKE    0x1000
#define CONTEXT_DEAD    0x0800
#define CONTEXT_ACTIVE  0x0400

#define OHCI1394_MAX_AT_REQ_RETRIES     0x2
#define OHCI1394_MAX_AT_RESP_RETRIES    0x2
#define OHCI1394_MAX_PHYS_RESP_RETRIES  0x8

#define FW_OHCI_MAJOR                   240
#define OHCI1394_REGISTER_SIZE          0x800
#define OHCI_LOOP_COUNT                 500
#define OHCI1394_PCI_HCI_Control        0x40
#define SELF_ID_BUF_SIZE                0x800
#define OHCI_TCODE_PHY_PACKET           0x0e

static char ohci_driver_name[] = KBUILD_MODNAME;

static inline void reg_write(const struct fw_ohci *ohci, int offset, u32 data)
{
        writel(data, ohci->registers + offset);
}

static inline u32 reg_read(const struct fw_ohci *ohci, int offset)
{
        return readl(ohci->registers + offset);
}

static inline void flush_writes(const struct fw_ohci *ohci)
{
        /* Do a dummy read to flush writes. */
        reg_read(ohci, OHCI1394_Version);
}

static int
ohci_update_phy_reg(struct fw_card *card, int addr,
                    int clear_bits, int set_bits)
{
        struct fw_ohci *ohci = fw_ohci(card);
        u32 val, old;

        reg_write(ohci, OHCI1394_PhyControl, OHCI1394_PhyControl_Read(addr));
        msleep(2);
        val = reg_read(ohci, OHCI1394_PhyControl);
        if ((val & OHCI1394_PhyControl_ReadDone) == 0) {
                fw_error("failed to set phy reg bits.\n");
                return -EBUSY;
        }

        old = OHCI1394_PhyControl_ReadData(val);
        old = (old & ~clear_bits) | set_bits;
        reg_write(ohci, OHCI1394_PhyControl,
                  OHCI1394_PhyControl_Write(addr, old));

        return 0;
}

static int ar_context_add_page(struct ar_context *ctx)
{
        struct device *dev = ctx->ohci->card.device;
        struct ar_buffer *ab;
        dma_addr_t ab_bus;
        size_t offset;

        ab = (struct ar_buffer *) __get_free_page(GFP_ATOMIC);
        if (ab == NULL)
                return -ENOMEM;

        ab_bus = dma_map_single(dev, ab, PAGE_SIZE, DMA_BIDIRECTIONAL);
        if (dma_mapping_error(ab_bus)) {
                free_page((unsigned long) ab);
                return -ENOMEM;
        }

        memset(&ab->descriptor, 0, sizeof ab->descriptor);
        ab->descriptor.control        = cpu_to_le16(descriptor_input_more |
                                                    descriptor_status |
                                                    descriptor_branch_always);
        offset = offsetof(struct ar_buffer, data);
        ab->descriptor.req_count      = cpu_to_le16(PAGE_SIZE - offset);
        ab->descriptor.data_address   = cpu_to_le32(ab_bus + offset);
        ab->descriptor.res_count      = cpu_to_le16(PAGE_SIZE - offset);
        ab->descriptor.branch_address = 0;

        dma_sync_single_for_device(dev, ab_bus, PAGE_SIZE, DMA_BIDIRECTIONAL);

        ctx->last_buffer->descriptor.branch_address = ab_bus | 1;
        ctx->last_buffer->next = ab;
        ctx->last_buffer = ab;

        reg_write(ctx->ohci, control_set(ctx->regs), CONTEXT_WAKE);
        flush_writes(ctx->ohci);

        return 0;
}

static __le32 *handle_ar_packet(struct ar_context *ctx, __le32 *buffer)
{
        struct fw_ohci *ohci = ctx->ohci;
        struct fw_packet p;
        u32 status, length, tcode;

        p.header[0] = le32_to_cpu(buffer[0]);
        p.header[1] = le32_to_cpu(buffer[1]);
        p.header[2] = le32_to_cpu(buffer[2]);

        tcode = (p.header[0] >> 4) & 0x0f;
        switch (tcode) {
        case TCODE_WRITE_QUADLET_REQUEST:
        case TCODE_READ_QUADLET_RESPONSE:
                p.header[3] = (__force __u32) buffer[3];
                p.header_length = 16;
                p.payload_length = 0;
                break;

        case TCODE_READ_BLOCK_REQUEST :
                p.header[3] = le32_to_cpu(buffer[3]);
                p.header_length = 16;
                p.payload_length = 0;
                break;

        case TCODE_WRITE_BLOCK_REQUEST:
        case TCODE_READ_BLOCK_RESPONSE:
        case TCODE_LOCK_REQUEST:
        case TCODE_LOCK_RESPONSE:
                p.header[3] = le32_to_cpu(buffer[3]);
                p.header_length = 16;
                p.payload_length = p.header[3] >> 16;
                break;

        case TCODE_WRITE_RESPONSE:
        case TCODE_READ_QUADLET_REQUEST:
        case OHCI_TCODE_PHY_PACKET:
                p.header_length = 12;
                p.payload_length = 0;
                break;
        }

        p.payload = (void *) buffer + p.header_length;

        /* FIXME: What to do about evt_* errors? */
        length = (p.header_length + p.payload_length + 3) / 4;
        status = le32_to_cpu(buffer[length]);

        p.ack        = ((status >> 16) & 0x1f) - 16;
        p.speed      = (status >> 21) & 0x7;
        p.timestamp  = status & 0xffff;
        p.generation = ohci->request_generation;

        /* The OHCI bus reset handler synthesizes a phy packet with
         * the new generation number when a bus reset happens (see
         * section 8.4.2.3).  This helps us determine when a request
         * was received and make sure we send the response in the same
         * generation.  We only need this for requests; for responses
         * we use the unique tlabel for finding the matching
         * request. */

        if (p.ack + 16 == 0x09)
                ohci->request_generation = (buffer[2] >> 16) & 0xff;
        else if (ctx == &ohci->ar_request_ctx)
                fw_core_handle_request(&ohci->card, &p);
        else
                fw_core_handle_response(&ohci->card, &p);

        return buffer + length + 1;
}

static void ar_context_tasklet(unsigned long data)
{
        struct ar_context *ctx = (struct ar_context *)data;
        struct fw_ohci *ohci = ctx->ohci;
        struct ar_buffer *ab;
        struct descriptor *d;
        void *buffer, *end;

        ab = ctx->current_buffer;
        d = &ab->descriptor;

        if (d->res_count == 0) {
                size_t size, rest, offset;

                /* This descriptor is finished and we may have a
                 * packet split across this and the next buffer. We
                 * reuse the page for reassembling the split packet. */

                offset = offsetof(struct ar_buffer, data);
                dma_unmap_single(ohci->card.device,
                                 ab->descriptor.data_address - offset,
                                 PAGE_SIZE, DMA_BIDIRECTIONAL);

                buffer = ab;
                ab = ab->next;
                d = &ab->descriptor;
                size = buffer + PAGE_SIZE - ctx->pointer;
                rest = le16_to_cpu(d->req_count) - le16_to_cpu(d->res_count);
                memmove(buffer, ctx->pointer, size);
                memcpy(buffer + size, ab->data, rest);
                ctx->current_buffer = ab;
                ctx->pointer = (void *) ab->data + rest;
                end = buffer + size + rest;

                while (buffer < end)
                        buffer = handle_ar_packet(ctx, buffer);

                free_page((unsigned long)buffer);
                ar_context_add_page(ctx);
        } else {
                buffer = ctx->pointer;
                ctx->pointer = end =
                        (void *) ab + PAGE_SIZE - le16_to_cpu(d->res_count);

                while (buffer < end)
                        buffer = handle_ar_packet(ctx, buffer);
        }
}

static int
ar_context_init(struct ar_context *ctx, struct fw_ohci *ohci, u32 regs)
{
        struct ar_buffer ab;

        ctx->regs        = regs;
        ctx->ohci        = ohci;
        ctx->last_buffer = &ab;
        tasklet_init(&ctx->tasklet, ar_context_tasklet, (unsigned long)ctx);

        ar_context_add_page(ctx);
        ar_context_add_page(ctx);
        ctx->current_buffer = ab.next;
        ctx->pointer = ctx->current_buffer->data;

        reg_write(ctx->ohci, command_ptr(ctx->regs), ab.descriptor.branch_address);
        reg_write(ctx->ohci, control_set(ctx->regs), CONTEXT_RUN);
        flush_writes(ctx->ohci);

        return 0;
}
 
static void context_tasklet(unsigned long data)
{
        struct context *ctx = (struct context *) data;
        struct fw_ohci *ohci = ctx->ohci;
        struct descriptor *d, *last;
        u32 address;
        int z;

        dma_sync_single_for_cpu(ohci->card.device, ctx->buffer_bus,
                                ctx->buffer_size, DMA_TO_DEVICE);

        d    = ctx->tail_descriptor;
        last = ctx->tail_descriptor_last;

        while (last->branch_address != 0) {
                address = le32_to_cpu(last->branch_address);
                z = address & 0xf;
                d = ctx->buffer + (address - ctx->buffer_bus) / sizeof *d;
                last = (z == 2) ? d : d + z - 1;

                if (!ctx->callback(ctx, d, last))
                        break;

                ctx->tail_descriptor      = d;
                ctx->tail_descriptor_last = last;
        }
}

static int
context_init(struct context *ctx, struct fw_ohci *ohci,
             size_t buffer_size, u32 regs,
             descriptor_callback_t callback)
{
        ctx->ohci = ohci;
        ctx->regs = regs;
        ctx->buffer_size = buffer_size;
        ctx->buffer = kmalloc(buffer_size, GFP_KERNEL);
        if (ctx->buffer == NULL)
                return -ENOMEM;

        tasklet_init(&ctx->tasklet, context_tasklet, (unsigned long)ctx);
        ctx->callback = callback;

        ctx->buffer_bus =
                dma_map_single(ohci->card.device, ctx->buffer,
                               buffer_size, DMA_TO_DEVICE);
        if (dma_mapping_error(ctx->buffer_bus)) {
                kfree(ctx->buffer);
                return -ENOMEM;
        }

        ctx->head_descriptor      = ctx->buffer;
        ctx->prev_descriptor      = ctx->buffer;
        ctx->tail_descriptor      = ctx->buffer;
        ctx->tail_descriptor_last = ctx->buffer;

        /* We put a dummy descriptor in the buffer that has a NULL
         * branch address and looks like it's been sent.  That way we
         * have a descriptor to append DMA programs to.  Also, the
         * ring buffer invariant is that it always has at least one
         * element so that head == tail means buffer full. */

        memset(ctx->head_descriptor, 0, sizeof *ctx->head_descriptor);
        ctx->head_descriptor->control = cpu_to_le16(descriptor_output_last);
        ctx->head_descriptor->transfer_status = cpu_to_le16(0x8011);
        ctx->head_descriptor++;

        return 0;
}

 static void
context_release(struct context *ctx)
{
        struct fw_card *card = &ctx->ohci->card;

        dma_unmap_single(card->device, ctx->buffer_bus,
                         ctx->buffer_size, DMA_TO_DEVICE);
        kfree(ctx->buffer);
}

static struct descriptor *
context_get_descriptors(struct context *ctx, int z, dma_addr_t *d_bus)
{
        struct descriptor *d, *tail, *end;

        d = ctx->head_descriptor;
        tail = ctx->tail_descriptor;
        end = ctx->buffer + ctx->buffer_size / sizeof(struct descriptor);

        if (d + z <= tail) {
                goto has_space;
        } else if (d > tail && d + z <= end) {
                goto has_space;
        } else if (d > tail && ctx->buffer + z <= tail) {
                d = ctx->buffer;
                goto has_space;
        }

        return NULL;

 has_space:
        memset(d, 0, z * sizeof *d);
        *d_bus = ctx->buffer_bus + (d - ctx->buffer) * sizeof *d;

        return d;
}

static void context_run(struct context *ctx, u32 extra)
{
        struct fw_ohci *ohci = ctx->ohci;

        reg_write(ohci, command_ptr(ctx->regs),
                  le32_to_cpu(ctx->tail_descriptor_last->branch_address));
        reg_write(ohci, control_clear(ctx->regs), ~0);
        reg_write(ohci, control_set(ctx->regs), CONTEXT_RUN | extra);
        flush_writes(ohci);
}

static void context_append(struct context *ctx,
                           struct descriptor *d, int z, int extra)
{
        dma_addr_t d_bus;

        d_bus = ctx->buffer_bus + (d - ctx->buffer) * sizeof *d;

        ctx->head_descriptor = d + z + extra;
        ctx->prev_descriptor->branch_address = cpu_to_le32(d_bus | z);
        ctx->prev_descriptor = z == 2 ? d : d + z - 1;

        dma_sync_single_for_device(ctx->ohci->card.device, ctx->buffer_bus,
                                   ctx->buffer_size, DMA_TO_DEVICE);

        reg_write(ctx->ohci, control_set(ctx->regs), CONTEXT_WAKE);
        flush_writes(ctx->ohci);
}

static void context_stop(struct context *ctx)
{
        u32 reg;
        int i;

        reg_write(ctx->ohci, control_clear(ctx->regs), CONTEXT_RUN);
        flush_writes(ctx->ohci);

        for (i = 0; i < 10; i++) {
                reg = reg_read(ctx->ohci, control_set(ctx->regs));
                if ((reg & CONTEXT_ACTIVE) == 0)
                        break;

                fw_notify("context_stop: still active (0x%08x)\n", reg);
                msleep(1);
        }
}

static void
do_packet_callbacks(struct fw_ohci *ohci, struct list_head *list)
{
        struct fw_packet *p, *next;

        list_for_each_entry_safe(p, next, list, link)
                p->callback(p, &ohci->card, p->ack);
}

static void
complete_transmission(struct fw_packet *packet,
                      int ack, struct list_head *list)
{
        list_move_tail(&packet->link, list);
        packet->ack = ack;
}

/* This function prepares the first packet in the context queue for
 * transmission.  Must always be called with the ochi->lock held to
 * ensure proper generation handling and locking around packet queue
 * manipulation. */
static void
at_context_setup_packet(struct at_context *ctx, struct list_head *list)
{
        struct fw_packet *packet;
        struct fw_ohci *ohci = ctx->ohci;
        int z, tcode;

        packet = fw_packet(ctx->list.next);

        memset(&ctx->d, 0, sizeof ctx->d);
        if (packet->payload_length > 0) {
                packet->payload_bus = dma_map_single(ohci->card.device,
                                                     packet->payload,
                                                     packet->payload_length,
                                                     DMA_TO_DEVICE);
                if (dma_mapping_error(packet->payload_bus)) {
                        complete_transmission(packet, RCODE_SEND_ERROR, list);
                        return;
                }

                ctx->d.more.control      =
                        cpu_to_le16(descriptor_output_more |
                                    descriptor_key_immediate);
                ctx->d.more.req_count    = cpu_to_le16(packet->header_length);
                ctx->d.more.res_count    = cpu_to_le16(packet->timestamp);
                ctx->d.last.control      =
                        cpu_to_le16(descriptor_output_last |
                                    descriptor_irq_always |
                                    descriptor_branch_always);
                ctx->d.last.req_count    = cpu_to_le16(packet->payload_length);
                ctx->d.last.data_address = cpu_to_le32(packet->payload_bus);
                z = 3;
        } else {
                ctx->d.more.control   =
                        cpu_to_le16(descriptor_output_last |
                                    descriptor_key_immediate |
                                    descriptor_irq_always |
                                    descriptor_branch_always);
                ctx->d.more.req_count = cpu_to_le16(packet->header_length);
                ctx->d.more.res_count = cpu_to_le16(packet->timestamp);
                z = 2;
        }

        /* The DMA format for asyncronous link packets is different
         * from the IEEE1394 layout, so shift the fields around
         * accordingly.  If header_length is 8, it's a PHY packet, to
         * which we need to prepend an extra quadlet. */
        if (packet->header_length > 8) {
                ctx->d.header[0] = cpu_to_le32((packet->header[0] & 0xffff) |
                                               (packet->speed << 16));
                ctx->d.header[1] = cpu_to_le32((packet->header[1] & 0xffff) |
                                               (packet->header[0] & 0xffff0000));
                ctx->d.header[2] = cpu_to_le32(packet->header[2]);

                tcode = (packet->header[0] >> 4) & 0x0f;
                if (TCODE_IS_BLOCK_PACKET(tcode))
                        ctx->d.header[3] = cpu_to_le32(packet->header[3]);
                else
                        ctx->d.header[3] = packet->header[3];
        } else {
                ctx->d.header[0] =
                        cpu_to_le32((OHCI1394_phy_tcode << 4) |
                                    (packet->speed << 16));
                ctx->d.header[1] = cpu_to_le32(packet->header[0]);
                ctx->d.header[2] = cpu_to_le32(packet->header[1]);
                ctx->d.more.req_count = cpu_to_le16(12);
        }

        /* FIXME: Document how the locking works. */
        if (ohci->generation == packet->generation) {
                reg_write(ctx->ohci, command_ptr(ctx->regs),
                          ctx->descriptor_bus | z);
                reg_write(ctx->ohci, control_set(ctx->regs),
                          CONTEXT_RUN | CONTEXT_WAKE);
                ctx->current_packet = packet;
        } else {
                /* We dont return error codes from this function; all
                 * transmission errors are reported through the
                 * callback. */
                complete_transmission(packet, RCODE_GENERATION, list);
        }
}

static void at_context_stop(struct at_context *ctx)
{
        u32 reg;

        reg_write(ctx->ohci, control_clear(ctx->regs), CONTEXT_RUN);

        reg = reg_read(ctx->ohci, control_set(ctx->regs));
        if (reg & CONTEXT_ACTIVE)
                fw_notify("Tried to stop context, but it is still active "
                          "(0x%08x).\n", reg);
}

static void at_context_tasklet(unsigned long data)
{
        struct at_context *ctx = (struct at_context *)data;
        struct fw_ohci *ohci = ctx->ohci;
        struct fw_packet *packet;
        LIST_HEAD(list);
        unsigned long flags;
        int evt;

        spin_lock_irqsave(&ohci->lock, flags);

        packet = fw_packet(ctx->list.next);

        at_context_stop(ctx);

        /* If the head of the list isn't the packet that just got
         * transmitted, the packet got cancelled before we finished
         * transmitting it. */
        if (ctx->current_packet != packet)
                goto skip_to_next;

        if (packet->payload_length > 0) {
                dma_unmap_single(ohci->card.device, packet->payload_bus,
                                 packet->payload_length, DMA_TO_DEVICE);
                evt = le16_to_cpu(ctx->d.last.transfer_status) & 0x1f;
                packet->timestamp = le16_to_cpu(ctx->d.last.res_count);
        }
        else {
                evt = le16_to_cpu(ctx->d.more.transfer_status) & 0x1f;
                packet->timestamp = le16_to_cpu(ctx->d.more.res_count);
        }

        if (evt < 16) {
                switch (evt) {
                case OHCI1394_evt_timeout:
                        /* Async response transmit timed out. */
                        complete_transmission(packet, RCODE_CANCELLED, &list);
                        break;

                case OHCI1394_evt_flushed:
                        /* The packet was flushed should give same
                         * error as when we try to use a stale
                         * generation count. */
                        complete_transmission(packet,
                                              RCODE_GENERATION, &list);
                        break;

                case OHCI1394_evt_missing_ack:
                        /* Using a valid (current) generation count,
                         * but the node is not on the bus or not
                         * sending acks. */
                        complete_transmission(packet, RCODE_NO_ACK, &list);
                        break;

                default:
                        complete_transmission(packet, RCODE_SEND_ERROR, &list);
                        break;
                }
        } else
                complete_transmission(packet, evt - 16, &list);

 skip_to_next:
        /* If more packets are queued, set up the next one. */
        if (!list_empty(&ctx->list))
                at_context_setup_packet(ctx, &list);

        spin_unlock_irqrestore(&ohci->lock, flags);

        do_packet_callbacks(ohci, &list);
}

static int
at_context_init(struct at_context *ctx, struct fw_ohci *ohci, u32 regs)
{
        INIT_LIST_HEAD(&ctx->list);

        ctx->descriptor_bus =
                dma_map_single(ohci->card.device, &ctx->d,
                               sizeof ctx->d, DMA_TO_DEVICE);
        if (dma_mapping_error(ctx->descriptor_bus))
                return -ENOMEM;

        ctx->regs = regs;
        ctx->ohci = ohci;

        tasklet_init(&ctx->tasklet, at_context_tasklet, (unsigned long)ctx);

        return 0;
}

#define header_get_destination(q)       (((q) >> 16) & 0xffff)
#define header_get_tcode(q)             (((q) >> 4) & 0x0f)
#define header_get_offset_high(q)       (((q) >> 0) & 0xffff)
#define header_get_data_length(q)       (((q) >> 16) & 0xffff)
#define header_get_extended_tcode(q)    (((q) >> 0) & 0xffff)

static void
handle_local_rom(struct fw_ohci *ohci, struct fw_packet *packet, u32 csr)
{
        struct fw_packet response;
        int tcode, length, i;

        tcode = header_get_tcode(packet->header[0]);
        if (TCODE_IS_BLOCK_PACKET(tcode))
                length = header_get_data_length(packet->header[3]);
        else
                length = 4;

        i = csr - CSR_CONFIG_ROM;
        if (i + length > CONFIG_ROM_SIZE) {
                fw_fill_response(&response, packet->header,
                                 RCODE_ADDRESS_ERROR, NULL, 0);
        } else if (!TCODE_IS_READ_REQUEST(tcode)) {
                fw_fill_response(&response, packet->header,
                                 RCODE_TYPE_ERROR, NULL, 0);
        } else {
                fw_fill_response(&response, packet->header, RCODE_COMPLETE,
                                 (void *) ohci->config_rom + i, length);
        }

        fw_core_handle_response(&ohci->card, &response);
}

static void
handle_local_lock(struct fw_ohci *ohci, struct fw_packet *packet, u32 csr)
{
        struct fw_packet response;
        int tcode, length, ext_tcode, sel;
        __be32 *payload, lock_old;
        u32 lock_arg, lock_data;

        tcode = header_get_tcode(packet->header[0]);
        length = header_get_data_length(packet->header[3]);
        payload = packet->payload;
        ext_tcode = header_get_extended_tcode(packet->header[3]);

        if (tcode == TCODE_LOCK_REQUEST &&
            ext_tcode == EXTCODE_COMPARE_SWAP && length == 8) {
                lock_arg = be32_to_cpu(payload[0]);
                lock_data = be32_to_cpu(payload[1]);
        } else if (tcode == TCODE_READ_QUADLET_REQUEST) {
                lock_arg = 0;
                lock_data = 0;
        } else {
                fw_fill_response(&response, packet->header,
                                 RCODE_TYPE_ERROR, NULL, 0);
                goto out;
        }

        sel = (csr - CSR_BUS_MANAGER_ID) / 4;
        reg_write(ohci, OHCI1394_CSRData, lock_data);
        reg_write(ohci, OHCI1394_CSRCompareData, lock_arg);
        reg_write(ohci, OHCI1394_CSRControl, sel);

        if (reg_read(ohci, OHCI1394_CSRControl) & 0x80000000)
                lock_old = cpu_to_be32(reg_read(ohci, OHCI1394_CSRData));
        else
                fw_notify("swap not done yet\n");

        fw_fill_response(&response, packet->header,
                         RCODE_COMPLETE, &lock_old, sizeof lock_old);
 out:
        fw_core_handle_response(&ohci->card, &response);
}

static void
handle_local_request(struct at_context *ctx, struct fw_packet *packet)
{
        u64 offset;
        u32 csr;

        packet->ack = ACK_PENDING;
        packet->callback(packet, &ctx->ohci->card, packet->ack);

        offset =
                ((unsigned long long)
                 header_get_offset_high(packet->header[1]) << 32) |
                packet->header[2];
        csr = offset - CSR_REGISTER_BASE;

        /* Handle config rom reads. */
        if (csr >= CSR_CONFIG_ROM && csr < CSR_CONFIG_ROM_END)
                handle_local_rom(ctx->ohci, packet, csr);
        else switch (csr) {
        case CSR_BUS_MANAGER_ID:
        case CSR_BANDWIDTH_AVAILABLE:
        case CSR_CHANNELS_AVAILABLE_HI:
        case CSR_CHANNELS_AVAILABLE_LO:
                handle_local_lock(ctx->ohci, packet, csr);
                break;
        default:
                if (ctx == &ctx->ohci->at_request_ctx)
                        fw_core_handle_request(&ctx->ohci->card, packet);
                else
                        fw_core_handle_response(&ctx->ohci->card, packet);
                break;
        }
}

static void
at_context_transmit(struct at_context *ctx, struct fw_packet *packet)
{
        LIST_HEAD(list);
        unsigned long flags;

        spin_lock_irqsave(&ctx->ohci->lock, flags);

        if (header_get_destination(packet->header[0]) == ctx->ohci->node_id &&
            ctx->ohci->generation == packet->generation) {
                spin_unlock_irqrestore(&ctx->ohci->lock, flags);
                handle_local_request(ctx, packet);
                return;
        }

        list_add_tail(&packet->link, &ctx->list);
        if (ctx->list.next == &packet->link)
                at_context_setup_packet(ctx, &list);

        spin_unlock_irqrestore(&ctx->ohci->lock, flags);

        do_packet_callbacks(ctx->ohci, &list);
}

static void bus_reset_tasklet(unsigned long data)
{
        struct fw_ohci *ohci = (struct fw_ohci *)data;
        int self_id_count, i, j, reg;
        int generation, new_generation;
        unsigned long flags;

        reg = reg_read(ohci, OHCI1394_NodeID);
        if (!(reg & OHCI1394_NodeID_idValid)) {
                fw_error("node ID not valid, new bus reset in progress\n");
                return;
        }
        ohci->node_id = reg & 0xffff;

        /* The count in the SelfIDCount register is the number of
         * bytes in the self ID receive buffer.  Since we also receive
         * the inverted quadlets and a header quadlet, we shift one
         * bit extra to get the actual number of self IDs. */

        self_id_count = (reg_read(ohci, OHCI1394_SelfIDCount) >> 3) & 0x3ff;
        generation = (le32_to_cpu(ohci->self_id_cpu[0]) >> 16) & 0xff;

        for (i = 1, j = 0; j < self_id_count; i += 2, j++) {
                if (ohci->self_id_cpu[i] != ~ohci->self_id_cpu[i + 1])
                        fw_error("inconsistent self IDs\n");
                ohci->self_id_buffer[j] = le32_to_cpu(ohci->self_id_cpu[i]);
        }

        /* Check the consistency of the self IDs we just read.  The
         * problem we face is that a new bus reset can start while we
         * read out the self IDs from the DMA buffer. If this happens,
         * the DMA buffer will be overwritten with new self IDs and we
         * will read out inconsistent data.  The OHCI specification
         * (section 11.2) recommends a technique similar to
         * linux/seqlock.h, where we remember the generation of the
         * self IDs in the buffer before reading them out and compare
         * it to the current generation after reading them out.  If
         * the two generations match we know we have a consistent set
         * of self IDs. */

        new_generation = (reg_read(ohci, OHCI1394_SelfIDCount) >> 16) & 0xff;
        if (new_generation != generation) {
                fw_notify("recursive bus reset detected, "
                          "discarding self ids\n");
                return;
        }

        /* FIXME: Document how the locking works. */
        spin_lock_irqsave(&ohci->lock, flags);

        ohci->generation = generation;
        at_context_stop(&ohci->at_request_ctx);
        at_context_stop(&ohci->at_response_ctx);
        reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);

        /* This next bit is unrelated to the AT context stuff but we
         * have to do it under the spinlock also.  If a new config rom
         * was set up before this reset, the old one is now no longer
         * in use and we can free it. Update the config rom pointers
         * to point to the current config rom and clear the
         * next_config_rom pointer so a new udpate can take place. */

        if (ohci->next_config_rom != NULL) {
                dma_free_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                  ohci->config_rom, ohci->config_rom_bus);
                ohci->config_rom      = ohci->next_config_rom;
                ohci->config_rom_bus  = ohci->next_config_rom_bus;
                ohci->next_config_rom = NULL;

                /* Restore config_rom image and manually update
                 * config_rom registers.  Writing the header quadlet
                 * will indicate that the config rom is ready, so we
                 * do that last. */
                reg_write(ohci, OHCI1394_BusOptions,
                          be32_to_cpu(ohci->config_rom[2]));
                ohci->config_rom[0] = cpu_to_be32(ohci->next_header);
                reg_write(ohci, OHCI1394_ConfigROMhdr, ohci->next_header);
        }

        spin_unlock_irqrestore(&ohci->lock, flags);

        fw_core_handle_bus_reset(&ohci->card, ohci->node_id, generation,
                                 self_id_count, ohci->self_id_buffer);
}

static irqreturn_t irq_handler(int irq, void *data)
{
        struct fw_ohci *ohci = data;
        u32 event, iso_event;
        int i;

        event = reg_read(ohci, OHCI1394_IntEventClear);

        if (!event)
                return IRQ_NONE;

        reg_write(ohci, OHCI1394_IntEventClear, event);

        if (event & OHCI1394_selfIDComplete)
                tasklet_schedule(&ohci->bus_reset_tasklet);

        if (event & OHCI1394_RQPkt)
                tasklet_schedule(&ohci->ar_request_ctx.tasklet);

        if (event & OHCI1394_RSPkt)
                tasklet_schedule(&ohci->ar_response_ctx.tasklet);

        if (event & OHCI1394_reqTxComplete)
                tasklet_schedule(&ohci->at_request_ctx.tasklet);

        if (event & OHCI1394_respTxComplete)
                tasklet_schedule(&ohci->at_response_ctx.tasklet);

        iso_event = reg_read(ohci, OHCI1394_IsoRecvIntEventClear);
        reg_write(ohci, OHCI1394_IsoRecvIntEventClear, iso_event);

        while (iso_event) {
                i = ffs(iso_event) - 1;
                tasklet_schedule(&ohci->ir_context_list[i].context.tasklet);
                iso_event &= ~(1 << i);
        }

        iso_event = reg_read(ohci, OHCI1394_IsoXmitIntEventClear);
        reg_write(ohci, OHCI1394_IsoXmitIntEventClear, iso_event);

        while (iso_event) {
                i = ffs(iso_event) - 1;
                tasklet_schedule(&ohci->it_context_list[i].context.tasklet);
                iso_event &= ~(1 << i);
        }

        return IRQ_HANDLED;
}

static int ohci_enable(struct fw_card *card, u32 *config_rom, size_t length)
{
        struct fw_ohci *ohci = fw_ohci(card);
        struct pci_dev *dev = to_pci_dev(card->device);

        /* When the link is not yet enabled, the atomic config rom
         * update mechanism described below in ohci_set_config_rom()
         * is not active.  We have to update ConfigRomHeader and
         * BusOptions manually, and the write to ConfigROMmap takes
         * effect immediately.  We tie this to the enabling of the
         * link, so we have a valid config rom before enabling - the
         * OHCI requires that ConfigROMhdr and BusOptions have valid
         * values before enabling.
         *
         * However, when the ConfigROMmap is written, some controllers
         * always read back quadlets 0 and 2 from the config rom to
         * the ConfigRomHeader and BusOptions registers on bus reset.
         * They shouldn't do that in this initial case where the link
         * isn't enabled.  This means we have to use the same
         * workaround here, setting the bus header to 0 and then write
         * the right values in the bus reset tasklet.
         */

        ohci->next_config_rom =
                dma_alloc_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                   &ohci->next_config_rom_bus, GFP_KERNEL);
        if (ohci->next_config_rom == NULL)
                return -ENOMEM;

        memset(ohci->next_config_rom, 0, CONFIG_ROM_SIZE);
        fw_memcpy_to_be32(ohci->next_config_rom, config_rom, length * 4);

        ohci->next_header = config_rom[0];
        ohci->next_config_rom[0] = 0;
        reg_write(ohci, OHCI1394_ConfigROMhdr, 0);
        reg_write(ohci, OHCI1394_BusOptions, config_rom[2]);
        reg_write(ohci, OHCI1394_ConfigROMmap, ohci->next_config_rom_bus);

        reg_write(ohci, OHCI1394_AsReqFilterHiSet, 0x80000000);

        if (request_irq(dev->irq, irq_handler,
                        SA_SHIRQ, ohci_driver_name, ohci)) {
                fw_error("Failed to allocate shared interrupt %d.\n",
                         dev->irq);
                dma_free_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                  ohci->config_rom, ohci->config_rom_bus);
                return -EIO;
        }

        reg_write(ohci, OHCI1394_HCControlSet,
                  OHCI1394_HCControl_linkEnable |
                  OHCI1394_HCControl_BIBimageValid);
        flush_writes(ohci);

        /* We are ready to go, initiate bus reset to finish the
         * initialization. */

        fw_core_initiate_bus_reset(&ohci->card, 1);

        return 0;
}

static int
ohci_set_config_rom(struct fw_card *card, u32 *config_rom, size_t length)
{
        struct fw_ohci *ohci;
        unsigned long flags;
        int retval = 0;
        __be32 *next_config_rom;
        dma_addr_t next_config_rom_bus;

        ohci = fw_ohci(card);

        /* When the OHCI controller is enabled, the config rom update
         * mechanism is a bit tricky, but easy enough to use.  See
         * section 5.5.6 in the OHCI specification.
         *
         * The OHCI controller caches the new config rom address in a
         * shadow register (ConfigROMmapNext) and needs a bus reset
         * for the changes to take place.  When the bus reset is
         * detected, the controller loads the new values for the
         * ConfigRomHeader and BusOptions registers from the specified
         * config rom and loads ConfigROMmap from the ConfigROMmapNext
         * shadow register. All automatically and atomically.
         *
         * Now, there's a twist to this story.  The automatic load of
         * ConfigRomHeader and BusOptions doesn't honor the
         * noByteSwapData bit, so with a be32 config rom, the
         * controller will load be32 values in to these registers
         * during the atomic update, even on litte endian
         * architectures.  The workaround we use is to put a 0 in the
         * header quadlet; 0 is endian agnostic and means that the
         * config rom isn't ready yet.  In the bus reset tasklet we
         * then set up the real values for the two registers.
         *
         * We use ohci->lock to avoid racing with the code that sets
         * ohci->next_config_rom to NULL (see bus_reset_tasklet).
         */

        next_config_rom =
                dma_alloc_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                   &next_config_rom_bus, GFP_KERNEL);
        if (next_config_rom == NULL)
                return -ENOMEM;

        spin_lock_irqsave(&ohci->lock, flags);

        if (ohci->next_config_rom == NULL) {
                ohci->next_config_rom = next_config_rom;
                ohci->next_config_rom_bus = next_config_rom_bus;

                memset(ohci->next_config_rom, 0, CONFIG_ROM_SIZE);
                fw_memcpy_to_be32(ohci->next_config_rom, config_rom,
                                  length * 4);

                ohci->next_header = config_rom[0];
                ohci->next_config_rom[0] = 0;

                reg_write(ohci, OHCI1394_ConfigROMmap,
                          ohci->next_config_rom_bus);
        } else {
                dma_free_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                  next_config_rom, next_config_rom_bus);
                retval = -EBUSY;
        }

        spin_unlock_irqrestore(&ohci->lock, flags);

        /* Now initiate a bus reset to have the changes take
         * effect. We clean up the old config rom memory and DMA
         * mappings in the bus reset tasklet, since the OHCI
         * controller could need to access it before the bus reset
         * takes effect. */
        if (retval == 0)
                fw_core_initiate_bus_reset(&ohci->card, 1);

        return retval;
}

static void ohci_send_request(struct fw_card *card, struct fw_packet *packet)
{
        struct fw_ohci *ohci = fw_ohci(card);

        at_context_transmit(&ohci->at_request_ctx, packet);
}

static void ohci_send_response(struct fw_card *card, struct fw_packet *packet)
{
        struct fw_ohci *ohci = fw_ohci(card);

        at_context_transmit(&ohci->at_response_ctx, packet);
}

static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
{
        struct fw_ohci *ohci = fw_ohci(card);
        LIST_HEAD(list);
        unsigned long flags;

        spin_lock_irqsave(&ohci->lock, flags);

        if (packet->ack == 0) {
                fw_notify("cancelling packet %p (header[0]=%08x)\n",
                          packet, packet->header[0]);

                complete_transmission(packet, RCODE_CANCELLED, &list);
        }

        spin_unlock_irqrestore(&ohci->lock, flags);

        do_packet_callbacks(ohci, &list);

        /* Return success if we actually cancelled something. */
        return list_empty(&list) ? -ENOENT : 0;
}

static int
ohci_enable_phys_dma(struct fw_card *card, int node_id, int generation)
{
        struct fw_ohci *ohci = fw_ohci(card);
        unsigned long flags;
        int n, retval = 0;

        /* FIXME:  Make sure this bitmask is cleared when we clear the busReset
         * interrupt bit.  Clear physReqResourceAllBuses on bus reset. */

        spin_lock_irqsave(&ohci->lock, flags);

        if (ohci->generation != generation) {
                retval = -ESTALE;
                goto out;
        }

        /* NOTE, if the node ID contains a non-local bus ID, physical DMA is
         * enabled for _all_ nodes on remote buses. */

        n = (node_id & 0xffc0) == LOCAL_BUS ? node_id & 0x3f : 63;
        if (n < 32)
                reg_write(ohci, OHCI1394_PhyReqFilterLoSet, 1 << n);
        else
                reg_write(ohci, OHCI1394_PhyReqFilterHiSet, 1 << (n - 32));

        flush_writes(ohci);
 out:
        spin_unlock_irqrestore(&ohci->lock, flags);
        return retval;
}

static int handle_ir_packet(struct context *context,
                            struct descriptor *d,
                            struct descriptor *last)
{
        struct iso_context *ctx =
                container_of(context, struct iso_context, context);
        struct db_descriptor *db = (struct db_descriptor *) d;
 
        if (db->first_res_count > 0 && db->second_res_count > 0)
                /* This descriptor isn't done yet, stop iteration. */
                return 0;

        if (le16_to_cpu(db->control) & descriptor_irq_always)
                /* FIXME: we should pass payload address here. */
                ctx->base.callback(&ctx->base,
                                   0, 0,
                                   ctx->base.callback_data);

        return 1;
}

#define ISO_BUFFER_SIZE (64 * 1024)

static int handle_it_packet(struct context *context,
                            struct descriptor *d,
                            struct descriptor *last)
{
        struct iso_context *ctx =
                container_of(context, struct iso_context, context);
 
        if (last->transfer_status == 0)
                /* This descriptor isn't done yet, stop iteration. */
                return 0;

        if (le16_to_cpu(last->control) & descriptor_irq_always)
                ctx->base.callback(&ctx->base,
                                   0, le16_to_cpu(last->res_count),
                                   ctx->base.callback_data);

        return 1;
}

static struct fw_iso_context *
ohci_allocate_iso_context(struct fw_card *card, int type)
{
        struct fw_ohci *ohci = fw_ohci(card);
        struct iso_context *ctx, *list;
        descriptor_callback_t callback;
        u32 *mask, regs;
        unsigned long flags;
        int index, retval;

        if (type == FW_ISO_CONTEXT_TRANSMIT) {
                mask = &ohci->it_context_mask;
                list = ohci->it_context_list;
                callback = handle_it_packet;
        } else {
                mask = &ohci->ir_context_mask;
                list = ohci->ir_context_list;
                callback = handle_ir_packet;
        }

        spin_lock_irqsave(&ohci->lock, flags);
        index = ffs(*mask) - 1;
        if (index >= 0)
                *mask &= ~(1 << index);
        spin_unlock_irqrestore(&ohci->lock, flags);

        if (index < 0)
                return ERR_PTR(-EBUSY);

        if (type == FW_ISO_CONTEXT_TRANSMIT)
                regs = OHCI1394_IsoXmitContextBase(index);
        else
                regs = OHCI1394_IsoRcvContextBase(index);
 
        ctx = &list[index];
        memset(ctx, 0, sizeof *ctx);
        retval = context_init(&ctx->context, ohci, ISO_BUFFER_SIZE,
                              regs, callback);
        if (retval < 0) {
                spin_lock_irqsave(&ohci->lock, flags);
                *mask |= 1 << index;
                spin_unlock_irqrestore(&ohci->lock, flags);
                return ERR_PTR(retval);
        }

        return &ctx->base;
}

static int ohci_start_iso(struct fw_iso_context *base, s32 cycle)
{
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        struct fw_ohci *ohci = ctx->context.ohci;
        u32 cycle_match = 0;
        int index;

        if (ctx->base.type == FW_ISO_CONTEXT_TRANSMIT) {
                index = ctx - ohci->it_context_list;
                if (cycle > 0)
                        cycle_match = IT_CONTEXT_CYCLE_MATCH_ENABLE |
                                (cycle & 0x7fff) << 16;
                
                reg_write(ohci, OHCI1394_IsoXmitIntEventClear, 1 << index);
                reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, 1 << index);
                context_run(&ctx->context, cycle_match);
        } else {
                index = ctx - ohci->ir_context_list;

                reg_write(ohci, OHCI1394_IsoRecvIntEventClear, 1 << index);
                reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, 1 << index);
                reg_write(ohci, context_match(ctx->context.regs),
                          0xf0000000 | ctx->base.channel);
                context_run(&ctx->context, IR_CONTEXT_DUAL_BUFFER_MODE);
        }

        return 0;
}

static int ohci_stop_iso(struct fw_iso_context *base)
{
        struct fw_ohci *ohci = fw_ohci(base->card);
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        int index;

        if (ctx->base.type == FW_ISO_CONTEXT_TRANSMIT) {
                index = ctx - ohci->it_context_list;
                reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, 1 << index);
        } else {
                index = ctx - ohci->ir_context_list;
                reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, 1 << index);
        }
        flush_writes(ohci);
        context_stop(&ctx->context);

        return 0;
}

static void ohci_free_iso_context(struct fw_iso_context *base)
{
        struct fw_ohci *ohci = fw_ohci(base->card);
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        unsigned long flags;
        int index;

        ohci_stop_iso(base);
        context_release(&ctx->context);

        spin_lock_irqsave(&ohci->lock, flags);

        if (ctx->base.type == FW_ISO_CONTEXT_TRANSMIT) {
                index = ctx - ohci->it_context_list;
                ohci->it_context_mask |= 1 << index;
        } else {
                index = ctx - ohci->ir_context_list;
                ohci->ir_context_mask |= 1 << index;
        }

        spin_unlock_irqrestore(&ohci->lock, flags);
}

static int
ohci_queue_iso_transmit(struct fw_iso_context *base,
                        struct fw_iso_packet *packet,
                        struct fw_iso_buffer *buffer,
                        unsigned long payload)
{
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        struct descriptor *d, *last, *pd;
        struct fw_iso_packet *p;
        __le32 *header;
        dma_addr_t d_bus, page_bus;
        u32 z, header_z, payload_z, irq;
        u32 payload_index, payload_end_index, next_page_index;
        int page, end_page, i, length, offset;

        /* FIXME: Cycle lost behavior should be configurable: lose
         * packet, retransmit or terminate.. */

        p = packet;
        payload_index = payload;

        if (p->skip)
                z = 1;
        else
                z = 2;
        if (p->header_length > 0)
                z++;

        /* Determine the first page the payload isn't contained in. */
        end_page = PAGE_ALIGN(payload_index + p->payload_length) >> PAGE_SHIFT;
        if (p->payload_length > 0)
                payload_z = end_page - (payload_index >> PAGE_SHIFT);
        else
                payload_z = 0;

        z += payload_z;

        /* Get header size in number of descriptors. */
        header_z = DIV_ROUND_UP(p->header_length, sizeof *d);

        d = context_get_descriptors(&ctx->context, z + header_z, &d_bus);
        if (d == NULL)
                return -ENOMEM;

        if (!p->skip) {
                d[0].control   = cpu_to_le16(descriptor_key_immediate);
                d[0].req_count = cpu_to_le16(8);

                header = (__le32 *) &d[1];
                header[0] = cpu_to_le32(it_header_sy(p->sy) |
                                        it_header_tag(p->tag) |
                                        it_header_tcode(TCODE_STREAM_DATA) |
                                        it_header_channel(ctx->base.channel) |
                                        it_header_speed(ctx->base.speed));
                header[1] =
                        cpu_to_le32(it_header_data_length(p->header_length +
                                                          p->payload_length));
        }

        if (p->header_length > 0) {
                d[2].req_count    = cpu_to_le16(p->header_length);
                d[2].data_address = cpu_to_le32(d_bus + z * sizeof *d);
                memcpy(&d[z], p->header, p->header_length);
        }

        pd = d + z - payload_z;
        payload_end_index = payload_index + p->payload_length;
        for (i = 0; i < payload_z; i++) {
                page               = payload_index >> PAGE_SHIFT;
                offset             = payload_index & ~PAGE_MASK;
                next_page_index    = (page + 1) << PAGE_SHIFT;
                length             =
                        min(next_page_index, payload_end_index) - payload_index;
                pd[i].req_count    = cpu_to_le16(length);

                page_bus = page_private(buffer->pages[page]);
                pd[i].data_address = cpu_to_le32(page_bus + offset);

                payload_index += length;
        }

        if (p->interrupt)
                irq = descriptor_irq_always;
        else
                irq = descriptor_no_irq;

        last = z == 2 ? d : d + z - 1;
        last->control |= cpu_to_le16(descriptor_output_last |
                                     descriptor_status |
                                     descriptor_branch_always |
                                     irq);

        context_append(&ctx->context, d, z, header_z);

        return 0;
}

static int
ohci_queue_iso_receive(struct fw_iso_context *base,
                       struct fw_iso_packet *packet,
                       struct fw_iso_buffer *buffer,
                       unsigned long payload)
{
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        struct db_descriptor *db = NULL;
        struct descriptor *d;
        struct fw_iso_packet *p;
        dma_addr_t d_bus, page_bus;
        u32 z, header_z, length, rest;
        int page, offset;
 
        /* FIXME: Cycle lost behavior should be configurable: lose
         * packet, retransmit or terminate.. */

        p = packet;
        z = 2;

        /* Get header size in number of descriptors. */
        header_z = DIV_ROUND_UP(p->header_length, sizeof *d);
        page     = payload >> PAGE_SHIFT;
        offset   = payload & ~PAGE_MASK;
        rest     = p->payload_length;

        /* FIXME: OHCI 1.0 doesn't support dual buffer receive */
        /* FIXME: handle descriptor_wait */
        /* FIXME: make packet-per-buffer/dual-buffer a context option */
        while (rest > 0) {
                d = context_get_descriptors(&ctx->context,
                                            z + header_z, &d_bus);
                if (d == NULL)
                        return -ENOMEM;

                db = (struct db_descriptor *) d;
                db->control = cpu_to_le16(descriptor_status |
                                          descriptor_branch_always);
                db->first_size = cpu_to_le16(ctx->base.header_size);
                db->first_req_count = cpu_to_le16(p->header_length);
                db->second_req_count = cpu_to_le16(p->payload_length);
                db->first_res_count = cpu_to_le16(db->first_req_count);
                db->second_res_count = cpu_to_le16(db->second_req_count);

                db->first_buffer = cpu_to_le32(d_bus + sizeof *db);
                
                if (offset + rest < PAGE_SIZE)
                        length = rest;
                else
                        length = PAGE_SIZE - offset;

                page_bus = page_private(buffer->pages[page]);
                db->second_buffer = cpu_to_le32(page_bus + offset);

                context_append(&ctx->context, d, z, header_z);
                offset = (offset + length) & ~PAGE_MASK;
                rest -= length;
                page++;
        }

        if (p->interrupt)
                db->control |= cpu_to_le16(descriptor_irq_always);
 
        return 0;
 }
 
static int
ohci_queue_iso(struct fw_iso_context *base,
               struct fw_iso_packet *packet,
               struct fw_iso_buffer *buffer,
               unsigned long payload)
{
        if (base->type == FW_ISO_CONTEXT_TRANSMIT)
                return ohci_queue_iso_transmit(base, packet, buffer, payload);
        else
                return ohci_queue_iso_receive(base, packet, buffer, payload);
}

static const struct fw_card_driver ohci_driver = {
        .name                   = ohci_driver_name,
        .enable                 = ohci_enable,
        .update_phy_reg         = ohci_update_phy_reg,
        .set_config_rom         = ohci_set_config_rom,
        .send_request           = ohci_send_request,
        .send_response          = ohci_send_response,
        .cancel_packet          = ohci_cancel_packet,
        .enable_phys_dma        = ohci_enable_phys_dma,

        .allocate_iso_context   = ohci_allocate_iso_context,
        .free_iso_context       = ohci_free_iso_context,
        .queue_iso              = ohci_queue_iso,
        .start_iso              = ohci_start_iso,
        .stop_iso               = ohci_stop_iso,
};

static int software_reset(struct fw_ohci *ohci)
{
        int i;

        reg_write(ohci, OHCI1394_HCControlSet, OHCI1394_HCControl_softReset);

        for (i = 0; i < OHCI_LOOP_COUNT; i++) {
                if ((reg_read(ohci, OHCI1394_HCControlSet) &
                     OHCI1394_HCControl_softReset) == 0)
                        return 0;
                msleep(1);
        }

        return -EBUSY;
}

/* ---------- pci subsystem interface ---------- */

enum {
        CLEANUP_SELF_ID,
        CLEANUP_REGISTERS,
        CLEANUP_IOMEM,
        CLEANUP_DISABLE,
        CLEANUP_PUT_CARD,
};

static int cleanup(struct fw_ohci *ohci, int stage, int code)
{
        struct pci_dev *dev = to_pci_dev(ohci->card.device);

        switch (stage) {
        case CLEANUP_SELF_ID:
                dma_free_coherent(ohci->card.device, SELF_ID_BUF_SIZE,
                                  ohci->self_id_cpu, ohci->self_id_bus);
        case CLEANUP_REGISTERS:
                kfree(ohci->it_context_list);
                kfree(ohci->ir_context_list);
                pci_iounmap(dev, ohci->registers);
        case CLEANUP_IOMEM:
                pci_release_region(dev, 0);
        case CLEANUP_DISABLE:
                pci_disable_device(dev);
        case CLEANUP_PUT_CARD:
                fw_card_put(&ohci->card);
        }

        return code;
}

static int __devinit
pci_probe(struct pci_dev *dev, const struct pci_device_id *ent)
{
        struct fw_ohci *ohci;
        u32 bus_options, max_receive, link_speed;
        u64 guid;
        int error_code;
        size_t size;

        ohci = kzalloc(sizeof *ohci, GFP_KERNEL);
        if (ohci == NULL) {
                fw_error("Could not malloc fw_ohci data.\n");
                return -ENOMEM;
        }

        fw_card_initialize(&ohci->card, &ohci_driver, &dev->dev);

        if (pci_enable_device(dev)) {
                fw_error("Failed to enable OHCI hardware.\n");
                return cleanup(ohci, CLEANUP_PUT_CARD, -ENODEV);
        }

        pci_set_master(dev);
        pci_write_config_dword(dev, OHCI1394_PCI_HCI_Control, 0);
        pci_set_drvdata(dev, ohci);

        spin_lock_init(&ohci->lock);

        tasklet_init(&ohci->bus_reset_tasklet,
                     bus_reset_tasklet, (unsigned long)ohci);

        if (pci_request_region(dev, 0, ohci_driver_name)) {
                fw_error("MMIO resource unavailable\n");
                return cleanup(ohci, CLEANUP_DISABLE, -EBUSY);
        }

        ohci->registers = pci_iomap(dev, 0, OHCI1394_REGISTER_SIZE);
        if (ohci->registers == NULL) {
                fw_error("Failed to remap registers\n");
                return cleanup(ohci, CLEANUP_IOMEM, -ENXIO);
        }

        if (software_reset(ohci)) {
                fw_error("Failed to reset ohci card.\n");
                return cleanup(ohci, CLEANUP_REGISTERS, -EBUSY);
        }

        /* Now enable LPS, which we need in order to start accessing
         * most of the registers.  In fact, on some cards (ALI M5251),
         * accessing registers in the SClk domain without LPS enabled
         * will lock up the machine.  Wait 50msec to make sure we have
         * full link enabled.  */
        reg_write(ohci, OHCI1394_HCControlSet,
                  OHCI1394_HCControl_LPS |
                  OHCI1394_HCControl_postedWriteEnable);
        flush_writes(ohci);
        msleep(50);

        reg_write(ohci, OHCI1394_HCControlClear,
                  OHCI1394_HCControl_noByteSwapData);

        reg_write(ohci, OHCI1394_LinkControlSet,
                  OHCI1394_LinkControl_rcvSelfID |
                  OHCI1394_LinkControl_cycleTimerEnable |
                  OHCI1394_LinkControl_cycleMaster);

        ar_context_init(&ohci->ar_request_ctx, ohci,
                        OHCI1394_AsReqRcvContextControlSet);

        ar_context_init(&ohci->ar_response_ctx, ohci,
                        OHCI1394_AsRspRcvContextControlSet);

        at_context_init(&ohci->at_request_ctx, ohci,
                        OHCI1394_AsReqTrContextControlSet);

        at_context_init(&ohci->at_response_ctx, ohci,
                        OHCI1394_AsRspTrContextControlSet);

        reg_write(ohci, OHCI1394_ATRetries,
                  OHCI1394_MAX_AT_REQ_RETRIES |
                  (OHCI1394_MAX_AT_RESP_RETRIES << 4) |
                  (OHCI1394_MAX_PHYS_RESP_RETRIES << 8));

        reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, ~0);
        ohci->it_context_mask = reg_read(ohci, OHCI1394_IsoRecvIntMaskSet);
        reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, ~0);
        size = sizeof(struct iso_context) * hweight32(ohci->it_context_mask);
        ohci->it_context_list = kzalloc(size, GFP_KERNEL);

        reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, ~0);
        ohci->ir_context_mask = reg_read(ohci, OHCI1394_IsoXmitIntMaskSet);
        reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, ~0);
        size = sizeof(struct iso_context) * hweight32(ohci->ir_context_mask);
        ohci->ir_context_list = kzalloc(size, GFP_KERNEL);

        if (ohci->it_context_list == NULL || ohci->ir_context_list == NULL) {
                fw_error("Out of memory for it/ir contexts.\n");
                return cleanup(ohci, CLEANUP_REGISTERS, -ENOMEM);
        }

        /* self-id dma buffer allocation */
        ohci->self_id_cpu = dma_alloc_coherent(ohci->card.device,
                                               SELF_ID_BUF_SIZE,
                                               &ohci->self_id_bus,
                                               GFP_KERNEL);
        if (ohci->self_id_cpu == NULL) {
                fw_error("Out of memory for self ID buffer.\n");
                return cleanup(ohci, CLEANUP_REGISTERS, -ENOMEM);
        }

        reg_write(ohci, OHCI1394_SelfIDBuffer, ohci->self_id_bus);
        reg_write(ohci, OHCI1394_PhyUpperBound, 0x00010000);
        reg_write(ohci, OHCI1394_IntEventClear, ~0);
        reg_write(ohci, OHCI1394_IntMaskClear, ~0);
        reg_write(ohci, OHCI1394_IntMaskSet,
                  OHCI1394_selfIDComplete |
                  OHCI1394_RQPkt | OHCI1394_RSPkt |
                  OHCI1394_reqTxComplete | OHCI1394_respTxComplete |
                  OHCI1394_isochRx | OHCI1394_isochTx |
                  OHCI1394_masterIntEnable);

        bus_options = reg_read(ohci, OHCI1394_BusOptions);
        max_receive = (bus_options >> 12) & 0xf;
        link_speed = bus_options & 0x7;
        guid = ((u64) reg_read(ohci, OHCI1394_GUIDHi) << 32) |
                reg_read(ohci, OHCI1394_GUIDLo);

        error_code = fw_card_add(&ohci->card, max_receive, link_speed, guid);
        if (error_code < 0)
                return cleanup(ohci, CLEANUP_SELF_ID, error_code);

        fw_notify("Added fw-ohci device %s.\n", dev->dev.bus_id);

        return 0;
}

static void pci_remove(struct pci_dev *dev)
{
        struct fw_ohci *ohci;

        ohci = pci_get_drvdata(dev);
        reg_write(ohci, OHCI1394_IntMaskClear, OHCI1394_masterIntEnable);
        fw_core_remove_card(&ohci->card);

        /* FIXME: Fail all pending packets here, now that the upper
         * layers can't queue any more. */

        software_reset(ohci);
        free_irq(dev->irq, ohci);
        cleanup(ohci, CLEANUP_SELF_ID, 0);

        fw_notify("Removed fw-ohci device.\n");
}

static struct pci_device_id pci_table[] = {
        { PCI_DEVICE_CLASS(PCI_CLASS_SERIAL_FIREWIRE_OHCI, ~0) },
        { }
};

MODULE_DEVICE_TABLE(pci, pci_table);

static struct pci_driver fw_ohci_pci_driver = {
        .name           = ohci_driver_name,
        .id_table       = pci_table,
        .probe          = pci_probe,
        .remove         = pci_remove,
};

MODULE_AUTHOR("Kristian Hoegsberg <krh@bitplanet.net>");
MODULE_DESCRIPTION("Driver for PCI OHCI IEEE1394 controllers");
MODULE_LICENSE("GPL");

static int __init fw_ohci_init(void)
{
        return pci_register_driver(&fw_ohci_pci_driver);
}

static void __exit fw_ohci_cleanup(void)
{
        pci_unregister_driver(&fw_ohci_pci_driver);
}

module_init(fw_ohci_init);
module_exit(fw_ohci_cleanup);