drivers/sh/maple/maple.c - linux - Git at Google

 /*
  * 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 <adrian@mcmen.demon.co.uk>");
 MODULE_DESCRIPTION("Maple bus driver for Dreamcast");
 MODULE_LICENSE("GPL v2");

 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];
 static const struct bus_type maple_bus_type;

 /**
  * 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 = kcalloc(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++)
 			__flush_purge_region(maple_sendbuf + i * PAGE_SIZE,
 					PAGE_SIZE);
 	}

 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;
 			__flush_invalidate_region(sh_cacheop_vaddr(recvbuf),
 					0x400);
 			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,
 				  const struct device_driver *drvptr)
 {
 	const 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 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
  */
 static const struct bus_type maple_bus_type = {
 	.name = "maple",
 	.match = maple_match_bus_driver,
 };

 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) {
 		retval = -ENOMEM;
 		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]);
 			retval = -ENOMEM;
 			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);
	/*
	* 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 <adrian@mcmen.demon.co.uk>");
	MODULE_DESCRIPTION("Maple bus driver for Dreamcast");
	MODULE_LICENSE("GPL v2");

	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];
	static const struct bus_type maple_bus_type;

	/**
	* 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 = kcalloc(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++)
	__flush_purge_region(maple_sendbuf + i * PAGE_SIZE,
	PAGE_SIZE);
	}

	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;
	__flush_invalidate_region(sh_cacheop_vaddr(recvbuf),
	0x400);
	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,
	const struct device_driver *drvptr)
	{
	const 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 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
	*/
	static const struct bus_type maple_bus_type = {
	.name = "maple",
	.match = maple_match_bus_driver,
	};

	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) {
	retval = -ENOMEM;
	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]);
	retval = -ENOMEM;
	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);