maple.c

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/*
 * 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 <linux/module.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 <[email protected]>");
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];

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);

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);
}

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);
}

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);