/*
 * Core maple bus functionality
 *
 *  Copyright (C) 2007 - 2009 Adrian McMenamin
 *  Copyright (C) 2001 - 2008 Paul Mundt
 *  Copyright (C) 2000 - 2001 YAEGASHI Takeshi
 *  Copyright (C) 2001 M. R. Brown
 *
 * 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/kernel.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/maple.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <asm/cacheflush.h>
#include <asm/dma.h>
#include <asm/io.h>
#include <mach/dma.h>
#include <mach/sysasic.h>

MODULE_AUTHOR("Adrian McMenamin <adrian@mcmen.demon.co.uk>");
MODULE_DESCRIPTION("Maple bus driver for Dreamcast");
MODULE_LICENSE("GPL v2");
MODULE_SUPPORTED_DEVICE("{{SEGA, Dreamcast/Maple}}");

static void maple_dma_handler(struct work_struct *work);
static void maple_vblank_handler(struct work_struct *work);

static DECLARE_WORK(maple_dma_process, maple_dma_handler);
static DECLARE_WORK(maple_vblank_process, maple_vblank_handler);

static LIST_HEAD(maple_waitq);
static LIST_HEAD(maple_sentq);

/* mutex to protect queue of waiting packets */
static DEFINE_MUTEX(maple_wlist_lock);

static struct maple_driver maple_unsupported_device;
static struct device maple_bus;
static int subdevice_map[MAPLE_PORTS];
static unsigned long *maple_sendbuf, *maple_sendptr, *maple_lastptr;
static unsigned long maple_pnp_time;
static int started, scanning, fullscan;
static struct kmem_cache *maple_queue_cache;

struct maple_device_specify {
        int port;
        int unit;
};

static bool checked[MAPLE_PORTS];
static bool empty[MAPLE_PORTS];
static struct maple_device *baseunits[MAPLE_PORTS];

/**
 * maple_driver_register - register a maple driver
 * @drv: maple driver to be registered.
 *
 * Registers the passed in @drv, while updating the bus type.
 * Devices with matching function IDs will be automatically probed.
 */
int maple_driver_register(struct maple_driver *drv)
{
        if (!drv)
                return -EINVAL;

        drv->drv.bus = &maple_bus_type;

        return driver_register(&drv->drv);
}
EXPORT_SYMBOL_GPL(maple_driver_register);

/**
 * maple_driver_unregister - unregister a maple driver.
 * @drv: maple driver to unregister.
 *
 * Cleans up after maple_driver_register(). To be invoked in the exit
 * path of any module drivers.
 */
void maple_driver_unregister(struct maple_driver *drv)
{
        driver_unregister(&drv->drv);
}
EXPORT_SYMBOL_GPL(maple_driver_unregister);

/* set hardware registers to enable next round of dma */
static void maple_dma_reset(void)
{
        __raw_writel(MAPLE_MAGIC, MAPLE_RESET);
        /* set trig type to 0 for software trigger, 1 for hardware (VBLANK) */
        __raw_writel(1, MAPLE_TRIGTYPE);
        /*
        * Maple system register
        * bits 31 - 16  timeout in units of 20nsec
        * bit 12        hard trigger - set 0 to keep responding to VBLANK
        * bits 9 - 8    set 00 for 2 Mbps, 01 for 1 Mbps
        * bits 3 - 0    delay (in 1.3ms) between VBLANK and start of DMA
        * max delay is 11
        */
        __raw_writel(MAPLE_2MBPS | MAPLE_TIMEOUT(0xFFFF), MAPLE_SPEED);
        __raw_writel(virt_to_phys(maple_sendbuf), MAPLE_DMAADDR);
        __raw_writel(1, MAPLE_ENABLE);
}

/**
 * maple_getcond_callback - setup handling MAPLE_COMMAND_GETCOND
 * @dev: device responding
 * @callback: handler callback
 * @interval: interval in jiffies between callbacks
 * @function: the function code for the device
 */
void maple_getcond_callback(struct maple_device *dev,
                        void (*callback) (struct mapleq *mq),
                        unsigned long interval, unsigned long function)
{
        dev->callback = callback;
        dev->interval = interval;
        dev->function = cpu_to_be32(function);
        dev->when = jiffies;
}
EXPORT_SYMBOL_GPL(maple_getcond_callback);

static int maple_dma_done(void)
{
        return (__raw_readl(MAPLE_STATE) & 1) == 0;
}

static void maple_release_device(struct device *dev)
{
        struct maple_device *mdev;
        struct mapleq *mq;

        mdev = to_maple_dev(dev);
        mq = mdev->mq;
        kmem_cache_free(maple_queue_cache, mq->recvbuf);
        kfree(mq);
        kfree(mdev);
}

/**
 * maple_add_packet - add a single instruction to the maple bus queue
 * @mdev: maple device
 * @function: function on device being queried
 * @command: maple command to add
 * @length: length of command string (in 32 bit words)
 * @data: remainder of command string
 */
int maple_add_packet(struct maple_device *mdev, u32 function, u32 command,
        size_t length, void *data)
{
        int ret = 0;
        void *sendbuf = NULL;

        if (length) {
                sendbuf = kzalloc(length * 4, GFP_KERNEL);
                if (!sendbuf) {
                        ret = -ENOMEM;
                        goto out;
                }
                ((__be32 *)sendbuf)[0] = cpu_to_be32(function);
        }

        mdev->mq->command = command;
        mdev->mq->length = length;
        if (length > 1)
                memcpy(sendbuf + 4, data, (length - 1) * 4);
        mdev->mq->sendbuf = sendbuf;

        mutex_lock(&maple_wlist_lock);
        list_add_tail(&mdev->mq->list, &maple_waitq);
        mutex_unlock(&maple_wlist_lock);
out:
        return ret;
}
EXPORT_SYMBOL_GPL(maple_add_packet);

static struct mapleq *maple_allocq(struct maple_device *mdev)
{
        struct mapleq *mq;

        mq = kzalloc(sizeof(*mq), GFP_KERNEL);
        if (!mq)
                goto failed_nomem;

        INIT_LIST_HEAD(&mq->list);
        mq->dev = mdev;
        mq->recvbuf = kmem_cache_zalloc(maple_queue_cache, GFP_KERNEL);
        if (!mq->recvbuf)
                goto failed_p2;
        mq->recvbuf->buf = &((mq->recvbuf->bufx)[0]);

        return mq;

failed_p2:
        kfree(mq);
failed_nomem:
        dev_err(&mdev->dev, "could not allocate memory for device (%d, %d)\n",
                mdev->port, mdev->unit);
        return NULL;
}

static struct maple_device *maple_alloc_dev(int port, int unit)
{
        struct maple_device *mdev;

        /* zero this out to avoid kobj subsystem
        * thinking it has already been registered */

        mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
        if (!mdev)
                return NULL;

        mdev->port = port;
        mdev->unit = unit;

        mdev->mq = maple_allocq(mdev);

        if (!mdev->mq) {
                kfree(mdev);
                return NULL;
        }
        mdev->dev.bus = &maple_bus_type;
        mdev->dev.parent = &maple_bus;
        init_waitqueue_head(&mdev->maple_wait);
        return mdev;
}

static void maple_free_dev(struct maple_device *mdev)
{
        kmem_cache_free(maple_queue_cache, mdev->mq->recvbuf);
        kfree(mdev->mq);
        kfree(mdev);
}

/* process the command queue into a maple command block
 * terminating command has bit 32 of first long set to 0
 */
static void maple_build_block(struct mapleq *mq)
{
        int port, unit, from, to, len;
        unsigned long *lsendbuf = mq->sendbuf;

        port = mq->dev->port & 3;
        unit = mq->dev->unit;
        len = mq->length;
        from = port << 6;
        to = (port << 6) | (unit > 0 ? (1 << (unit - 1)) & 0x1f : 0x20);

        *maple_lastptr &= 0x7fffffff;
        maple_lastptr = maple_sendptr;

        *maple_sendptr++ = (port << 16) | len | 0x80000000;
        *maple_sendptr++ = virt_to_phys(mq->recvbuf->buf);
        *maple_sendptr++ =
            mq->command | (to << 8) | (from << 16) | (len << 24);
        while (len-- > 0)
                *maple_sendptr++ = *lsendbuf++;
}

/* build up command queue */
static void maple_send(void)
{
        int i, maple_packets = 0;
        struct mapleq *mq, *nmq;

        if (!maple_dma_done())
                return;

        /* disable DMA */
        __raw_writel(0, MAPLE_ENABLE);

        if (!list_empty(&maple_sentq))
                goto finish;

        mutex_lock(&maple_wlist_lock);
        if (list_empty(&maple_waitq)) {
                mutex_unlock(&maple_wlist_lock);
                goto finish;
        }

        maple_lastptr = maple_sendbuf;
        maple_sendptr = maple_sendbuf;

        list_for_each_entry_safe(mq, nmq, &maple_waitq, list) {
                maple_build_block(mq);
                list_del_init(&mq->list);
                list_add_tail(&mq->list, &maple_sentq);
                if (maple_packets++ > MAPLE_MAXPACKETS)
                        break;
        }
        mutex_unlock(&maple_wlist_lock);
        if (maple_packets > 0) {
                for (i = 0; i < (1 << MAPLE_DMA_PAGES); i++)
                        dma_cache_sync(0, maple_sendbuf + i * PAGE_SIZE,
                                       PAGE_SIZE, DMA_BIDIRECTIONAL);
        }

finish:
        maple_dma_reset();
}

/* check if there is a driver registered likely to match this device */
static int maple_check_matching_driver(struct device_driver *driver,
                                        void *devptr)
{
        struct maple_driver *maple_drv;
        struct maple_device *mdev;

        mdev = devptr;
        maple_drv = to_maple_driver(driver);
        if (mdev->devinfo.function & cpu_to_be32(maple_drv->function))
                return 1;
        return 0;
}

static void maple_detach_driver(struct maple_device *mdev)
{
        device_unregister(&mdev->dev);
}

/* process initial MAPLE_COMMAND_DEVINFO for each device or port */
static void maple_attach_driver(struct maple_device *mdev)
{
        char *p, *recvbuf;
        unsigned long function;
        int matched, error;

        recvbuf = mdev->mq->recvbuf->buf;
        /* copy the data as individual elements in
        * case of memory optimisation */
        memcpy(&mdev->devinfo.function, recvbuf + 4, 4);
        memcpy(&mdev->devinfo.function_data[0], recvbuf + 8, 12);
        memcpy(&mdev->devinfo.area_code, recvbuf + 20, 1);
        memcpy(&mdev->devinfo.connector_direction, recvbuf + 21, 1);
        memcpy(&mdev->devinfo.product_name[0], recvbuf + 22, 30);
        memcpy(&mdev->devinfo.standby_power, recvbuf + 112, 2);
        memcpy(&mdev->devinfo.max_power, recvbuf + 114, 2);
        memcpy(mdev->product_name, mdev->devinfo.product_name, 30);
        mdev->product_name[30] = '\0';
        memcpy(mdev->product_licence, mdev->devinfo.product_licence, 60);
        mdev->product_licence[60] = '\0';

        for (p = mdev->product_name + 29; mdev->product_name <= p; p--)
                if (*p == ' ')
                        *p = '\0';
                else
                        break;
        for (p = mdev->product_licence + 59; mdev->product_licence <= p; p--)
                if (*p == ' ')
                        *p = '\0';
                else
                        break;

        function = be32_to_cpu(mdev->devinfo.function);

        dev_info(&mdev->dev, "detected %s: function 0x%lX: at (%d, %d)\n",
                mdev->product_name, function, mdev->port, mdev->unit);

        if (function > 0x200) {
                /* Do this silently - as not a real device */
                function = 0;
                mdev->driver = &maple_unsupported_device;
                dev_set_name(&mdev->dev, "%d:0.port", mdev->port);
        } else {
                matched =
                        bus_for_each_drv(&maple_bus_type, NULL, mdev,
                                maple_check_matching_driver);

                if (matched == 0) {
                        /* Driver does not exist yet */
                        dev_info(&mdev->dev, "no driver found\n");
                        mdev->driver = &maple_unsupported_device;
                }
                dev_set_name(&mdev->dev, "%d:0%d.%lX", mdev->port,
                             mdev->unit, function);
        }

        mdev->function = function;
        mdev->dev.release = &maple_release_device;

        atomic_set(&mdev->busy, 0);
        error = device_register(&mdev->dev);
        if (error) {
                dev_warn(&mdev->dev, "could not register device at"
                        " (%d, %d), with error 0x%X\n", mdev->unit,
                        mdev->port, error);
                maple_free_dev(mdev);
                mdev = NULL;
                return;
        }
}

/*
 * if device has been registered for the given
 * port and unit then return 1 - allows identification
 * of which devices need to be attached or detached
 */
static int check_maple_device(struct device *device, void *portptr)
{
        struct maple_device_specify *ds;
        struct maple_device *mdev;

        ds = portptr;
        mdev = to_maple_dev(device);
        if (mdev->port == ds->port && mdev->unit == ds->unit)
                return 1;
        return 0;
}

static int setup_maple_commands(struct device *device, void *ignored)
{
        int add;
        struct maple_device *mdev = to_maple_dev(device);
        if (mdev->interval > 0 && atomic_read(&mdev->busy) == 0 &&
                time_after(jiffies, mdev->when)) {
                /* bounce if we cannot add */
                add = maple_add_packet(mdev,
                        be32_to_cpu(mdev->devinfo.function),
                        MAPLE_COMMAND_GETCOND, 1, NULL);
                if (!add)
                        mdev->when = jiffies + mdev->interval;
        } else {
                if (time_after(jiffies, maple_pnp_time))
                        /* Ensure we don't have block reads and devinfo
                        * calls interfering with one another - so flag the
                        * device as busy */
                        if (atomic_read(&mdev->busy) == 0) {
                                atomic_set(&mdev->busy, 1);
                                maple_add_packet(mdev, 0,
                                        MAPLE_COMMAND_DEVINFO, 0, NULL);
                        }
        }
        return 0;
}

/* VBLANK bottom half - implemented via workqueue */
static void maple_vblank_handler(struct work_struct *work)
{
        int x, locking;
        struct maple_device *mdev;

        if (!maple_dma_done())
                return;

        __raw_writel(0, MAPLE_ENABLE);

        if (!list_empty(&maple_sentq))
                goto finish;

        /*
        * Set up essential commands - to fetch data and
        * check devices are still present
        */
        bus_for_each_dev(&maple_bus_type, NULL, NULL,
                setup_maple_commands);

        if (time_after(jiffies, maple_pnp_time)) {
                /*
                * Scan the empty ports - bus is flakey and may have
                * mis-reported emptyness
                */
                for (x = 0; x < MAPLE_PORTS; x++) {
                        if (checked[x] && empty[x]) {
                                mdev = baseunits[x];
                                if (!mdev)
                                        break;
                                atomic_set(&mdev->busy, 1);
                                locking = maple_add_packet(mdev, 0,
                                        MAPLE_COMMAND_DEVINFO, 0, NULL);
                                if (!locking)
                                        break;
                                }
                        }

                maple_pnp_time = jiffies + MAPLE_PNP_INTERVAL;
        }

finish:
        maple_send();
}

/* handle devices added via hotplugs - placing them on queue for DEVINFO */
static void maple_map_subunits(struct maple_device *mdev, int submask)
{
        int retval, k, devcheck;
        struct maple_device *mdev_add;
        struct maple_device_specify ds;

        ds.port = mdev->port;
        for (k = 0; k < 5; k++) {
                ds.unit = k + 1;
                retval =
                    bus_for_each_dev(&maple_bus_type, NULL, &ds,
                                     check_maple_device);
                if (retval) {
                        submask = submask >> 1;
                        continue;
                }
                devcheck = submask & 0x01;
                if (devcheck) {
                        mdev_add = maple_alloc_dev(mdev->port, k + 1);
                        if (!mdev_add)
                                return;
                        atomic_set(&mdev_add->busy, 1);
                        maple_add_packet(mdev_add, 0, MAPLE_COMMAND_DEVINFO,
                                0, NULL);
                        /* mark that we are checking sub devices */
                        scanning = 1;
                }
                submask = submask >> 1;
        }
}

/* mark a device as removed */
static void maple_clean_submap(struct maple_device *mdev)
{
        int killbit;

        killbit = (mdev->unit > 0 ? (1 << (mdev->unit - 1)) & 0x1f : 0x20);
        killbit = ~killbit;
        killbit &= 0xFF;
        subdevice_map[mdev->port] = subdevice_map[mdev->port] & killbit;
}

/* handle empty port or hotplug removal */
static void maple_response_none(struct maple_device *mdev)
{
        maple_clean_submap(mdev);

        if (likely(mdev->unit != 0)) {
                /*
                * Block devices play up
                * and give the impression they have
                * been removed even when still in place or
                * trip the mtd layer when they have
                * really gone - this code traps that eventuality
                * and ensures we aren't overloaded with useless
                * error messages
                */
                if (mdev->can_unload) {
                        if (!mdev->can_unload(mdev)) {
                                atomic_set(&mdev->busy, 2);
                                wake_up(&mdev->maple_wait);
                                return;
                        }
                }

                dev_info(&mdev->dev, "detaching device at (%d, %d)\n",
                        mdev->port, mdev->unit);
                maple_detach_driver(mdev);
                return;
        } else {
                if (!started || !fullscan) {
                        if (checked[mdev->port] == false) {
                                checked[mdev->port] = true;
                                empty[mdev->port] = true;
                                dev_info(&mdev->dev, "no devices"
                                        " to port %d\n", mdev->port);
                        }
                        return;
                }
        }
        /* Some hardware devices generate false detach messages on unit 0 */
        atomic_set(&mdev->busy, 0);
}

/* preprocess hotplugs or scans */
static void maple_response_devinfo(struct maple_device *mdev,
                                   char *recvbuf)
{
        char submask;
        if (!started || (scanning == 2) || !fullscan) {
                if ((mdev->unit == 0) && (checked[mdev->port] == false)) {
                        checked[mdev->port] = true;
                        maple_attach_driver(mdev);
                } else {
                        if (mdev->unit != 0)
                                maple_attach_driver(mdev);
                        if (mdev->unit == 0) {
                                empty[mdev->port] = false;
                                maple_attach_driver(mdev);
                        }
                }
        }
        if (mdev->unit == 0) {
                submask = recvbuf[2] & 0x1F;
                if (submask ^ subdevice_map[mdev->port]) {
                        maple_map_subunits(mdev, submask);
                        subdevice_map[mdev->port] = submask;
                }
        }
}

static void maple_response_fileerr(struct maple_device *mdev, void *recvbuf)
{
        if (mdev->fileerr_handler) {
                mdev->fileerr_handler(mdev, recvbuf);
                return;
        } else
                dev_warn(&mdev->dev, "device at (%d, %d) reports"
                        "file error 0x%X\n", mdev->port, mdev->unit,
                        ((int *)recvbuf)[1]);
}

static void maple_port_rescan(void)
{
        int i;
        struct maple_device *mdev;

        fullscan = 1;
        for (i = 0; i < MAPLE_PORTS; i++) {
                if (checked[i] == false) {
                        fullscan = 0;
                        mdev = baseunits[i];
                        maple_add_packet(mdev, 0, MAPLE_COMMAND_DEVINFO,
                                0, NULL);
                }
        }
}

/* maple dma end bottom half - implemented via workqueue */
static void maple_dma_handler(struct work_struct *work)
{
        struct mapleq *mq, *nmq;
        struct maple_device *mdev;
        char *recvbuf;
        enum maple_code code;

        if (!maple_dma_done())
                return;
        __raw_writel(0, MAPLE_ENABLE);
        if (!list_empty(&maple_sentq)) {
                list_for_each_entry_safe(mq, nmq, &maple_sentq, list) {
                        mdev = mq->dev;
                        recvbuf = mq->recvbuf->buf;
                        dma_cache_sync(&mdev->dev, recvbuf, 0x400,
                                DMA_FROM_DEVICE);
                        code = recvbuf[0];
                        kfree(mq->sendbuf);
                        list_del_init(&mq->list);
                        switch (code) {
                        case MAPLE_RESPONSE_NONE:
                                maple_response_none(mdev);
                                break;

                        case MAPLE_RESPONSE_DEVINFO:
                                maple_response_devinfo(mdev, recvbuf);
                                atomic_set(&mdev->busy, 0);
                                break;

                        case MAPLE_RESPONSE_DATATRF:
                                if (mdev->callback)
                                        mdev->callback(mq);
                                atomic_set(&mdev->busy, 0);
                                wake_up(&mdev->maple_wait);
                                break;

                        case MAPLE_RESPONSE_FILEERR:
                                maple_response_fileerr(mdev, recvbuf);
                                atomic_set(&mdev->busy, 0);
                                wake_up(&mdev->maple_wait);
                                break;

                        case MAPLE_RESPONSE_AGAIN:
                        case MAPLE_RESPONSE_BADCMD:
                        case MAPLE_RESPONSE_BADFUNC:
                                dev_warn(&mdev->dev, "non-fatal error"
                                        " 0x%X at (%d, %d)\n", code,
                                        mdev->port, mdev->unit);
                                atomic_set(&mdev->busy, 0);
                                break;

                        case MAPLE_RESPONSE_ALLINFO:
                                dev_notice(&mdev->dev, "extended"
                                " device information request for (%d, %d)"
                                " but call is not supported\n", mdev->port,
                                mdev->unit);
                                atomic_set(&mdev->busy, 0);
                                break;

                        case MAPLE_RESPONSE_OK:
                                atomic_set(&mdev->busy, 0);
                                wake_up(&mdev->maple_wait);
                                break;

                        default:
                                break;
                        }
                }
                /* if scanning is 1 then we have subdevices to check */
                if (scanning == 1) {
                        maple_send();
                        scanning = 2;
                } else
                        scanning = 0;
                /*check if we have actually tested all ports yet */
                if (!fullscan)
                        maple_port_rescan();
                /* mark that we have been through the first scan */
                started = 1;
        }
        maple_send();
}

static irqreturn_t maple_dma_interrupt(int irq, void *dev_id)
{
        /* Load everything into the bottom half */
        schedule_work(&maple_dma_process);
        return IRQ_HANDLED;
}

static irqreturn_t maple_vblank_interrupt(int irq, void *dev_id)
{
        schedule_work(&maple_vblank_process);
        return IRQ_HANDLED;
}

static int maple_set_dma_interrupt_handler(void)
{
        return request_irq(HW_EVENT_MAPLE_DMA, maple_dma_interrupt,
                IRQF_SHARED, "maple bus DMA", &maple_unsupported_device);
}

static int maple_set_vblank_interrupt_handler(void)
{
        return request_irq(HW_EVENT_VSYNC, maple_vblank_interrupt,
                IRQF_SHARED, "maple bus VBLANK", &maple_unsupported_device);
}

static int maple_get_dma_buffer(void)
{
        maple_sendbuf =
            (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
                                      MAPLE_DMA_PAGES);
        if (!maple_sendbuf)
                return -ENOMEM;
        return 0;
}

static int maple_match_bus_driver(struct device *devptr,
                                  struct device_driver *drvptr)
{
        struct maple_driver *maple_drv = to_maple_driver(drvptr);
        struct maple_device *maple_dev = to_maple_dev(devptr);

        /* Trap empty port case */
        if (maple_dev->devinfo.function == 0xFFFFFFFF)
                return 0;
        else if (maple_dev->devinfo.function &
                 cpu_to_be32(maple_drv->function))
                return 1;
        return 0;
}

static int maple_bus_uevent(struct device *dev,
                            struct kobj_uevent_env *env)
{
        return 0;
}

static void maple_bus_release(struct device *dev)
{
}

static struct maple_driver maple_unsupported_device = {
        .drv = {
                .name = "maple_unsupported_device",
                .bus = &maple_bus_type,
        },
};
/*
 * maple_bus_type - core maple bus structure
 */
struct bus_type maple_bus_type = {
        .name = "maple",
        .match = maple_match_bus_driver,
        .uevent = maple_bus_uevent,
};
EXPORT_SYMBOL_GPL(maple_bus_type);

static struct device maple_bus = {
        .init_name = "maple",
        .release = maple_bus_release,
};

static int __init maple_bus_init(void)
{
        int retval, i;
        struct maple_device *mdev[MAPLE_PORTS];

        __raw_writel(0, MAPLE_ENABLE);

        retval = device_register(&maple_bus);
        if (retval)
                goto cleanup;

        retval = bus_register(&maple_bus_type);
        if (retval)
                goto cleanup_device;

        retval = driver_register(&maple_unsupported_device.drv);
        if (retval)
                goto cleanup_bus;

        /* allocate memory for maple bus dma */
        retval = maple_get_dma_buffer();
        if (retval) {
                dev_err(&maple_bus, "failed to allocate DMA buffers\n");
                goto cleanup_basic;
        }

        /* set up DMA interrupt handler */
        retval = maple_set_dma_interrupt_handler();
        if (retval) {
                dev_err(&maple_bus, "bus failed to grab maple "
                        "DMA IRQ\n");
                goto cleanup_dma;
        }

        /* set up VBLANK interrupt handler */
        retval = maple_set_vblank_interrupt_handler();
        if (retval) {
                dev_err(&maple_bus, "bus failed to grab VBLANK IRQ\n");
                goto cleanup_irq;
        }

        maple_queue_cache = KMEM_CACHE(maple_buffer, SLAB_HWCACHE_ALIGN);

        if (!maple_queue_cache)
                goto cleanup_bothirqs;

        INIT_LIST_HEAD(&maple_waitq);
        INIT_LIST_HEAD(&maple_sentq);

        /* setup maple ports */
        for (i = 0; i < MAPLE_PORTS; i++) {
                checked[i] = false;
                empty[i] = false;
                mdev[i] = maple_alloc_dev(i, 0);
                if (!mdev[i]) {
                        while (i-- > 0)
                                maple_free_dev(mdev[i]);
                        goto cleanup_cache;
                }
                baseunits[i] = mdev[i];
                atomic_set(&mdev[i]->busy, 1);
                maple_add_packet(mdev[i], 0, MAPLE_COMMAND_DEVINFO, 0, NULL);
                subdevice_map[i] = 0;
        }

        maple_pnp_time = jiffies + HZ;
        /* prepare initial queue */
        maple_send();
        dev_info(&maple_bus, "bus core now registered\n");

        return 0;

cleanup_cache:
        kmem_cache_destroy(maple_queue_cache);

cleanup_bothirqs:
        free_irq(HW_EVENT_VSYNC, 0);

cleanup_irq:
        free_irq(HW_EVENT_MAPLE_DMA, 0);

cleanup_dma:
        free_pages((unsigned long) maple_sendbuf, MAPLE_DMA_PAGES);

cleanup_basic:
        driver_unregister(&maple_unsupported_device.drv);

cleanup_bus:
        bus_unregister(&maple_bus_type);

cleanup_device:
        device_unregister(&maple_bus);

cleanup:
        printk(KERN_ERR "Maple bus registration failed\n");
        return retval;
}
/* Push init to later to ensure hardware gets detected */
fs_initcall(maple_bus_init);