arch/ia64/sn/pci/pci_dma.c - linux - Git at Google

 /*
  * 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.
  *
  * Copyright (C) 2000,2002-2005 Silicon Graphics, Inc. All rights reserved.
  *
  * Routines for PCI DMA mapping.  See Documentation/DMA-API.txt for
  * a description of how these routines should be used.
  */

 #include <linux/module.h>
 #include <linux/dma-attrs.h>
 #include <asm/dma.h>
 #include <asm/sn/intr.h>
 #include <asm/sn/pcibus_provider_defs.h>
 #include <asm/sn/pcidev.h>
 #include <asm/sn/sn_sal.h>

 #define SG_ENT_VIRT_ADDRESS(sg)	(sg_virt((sg)))
 #define SG_ENT_PHYS_ADDRESS(SG)	virt_to_phys(SG_ENT_VIRT_ADDRESS(SG))

 /**
  * sn_dma_supported - test a DMA mask
  * @dev: device to test
  * @mask: DMA mask to test
  *
  * Return whether the given PCI device DMA address mask can be supported
  * properly.  For example, if your device can only drive the low 24-bits
  * during PCI bus mastering, then you would pass 0x00ffffff as the mask to
  * this function.  Of course, SN only supports devices that have 32 or more
  * address bits when using the PMU.
  */
 int sn_dma_supported(struct device *dev, u64 mask)
 {
 	BUG_ON(dev->bus != &pci_bus_type);

 	if (mask < 0x7fffffff)
 		return 0;
 	return 1;
 }
 EXPORT_SYMBOL(sn_dma_supported);

 /**
  * sn_dma_set_mask - set the DMA mask
  * @dev: device to set
  * @dma_mask: new mask
  *
  * Set @dev's DMA mask if the hw supports it.
  */
 int sn_dma_set_mask(struct device *dev, u64 dma_mask)
 {
 	BUG_ON(dev->bus != &pci_bus_type);

 	if (!sn_dma_supported(dev, dma_mask))
 		return 0;

 	*dev->dma_mask = dma_mask;
 	return 1;
 }
 EXPORT_SYMBOL(sn_dma_set_mask);

 /**
  * sn_dma_alloc_coherent - allocate memory for coherent DMA
  * @dev: device to allocate for
  * @size: size of the region
  * @dma_handle: DMA (bus) address
  * @flags: memory allocation flags
  *
  * dma_alloc_coherent() returns a pointer to a memory region suitable for
  * coherent DMA traffic to/from a PCI device.  On SN platforms, this means
  * that @dma_handle will have the %PCIIO_DMA_CMD flag set.
  *
  * This interface is usually used for "command" streams (e.g. the command
  * queue for a SCSI controller).  See Documentation/DMA-API.txt for
  * more information.
  */
 void *sn_dma_alloc_coherent(struct device *dev, size_t size,
 			    dma_addr_t * dma_handle, gfp_t flags)
 {
 	void *cpuaddr;
 	unsigned long phys_addr;
 	int node;
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);

 	BUG_ON(dev->bus != &pci_bus_type);

 	/*
 	 * Allocate the memory.
 	 */
 	node = pcibus_to_node(pdev->bus);
 	if (likely(node >=0)) {
 		struct page *p = alloc_pages_node(node, flags, get_order(size));

 		if (likely(p))
 			cpuaddr = page_address(p);
 		else
 			return NULL;
 	} else
 		cpuaddr = (void *)__get_free_pages(flags, get_order(size));

 	if (unlikely(!cpuaddr))
 		return NULL;

 	memset(cpuaddr, 0x0, size);

 	/* physical addr. of the memory we just got */
 	phys_addr = __pa(cpuaddr);

 	/*
 	 * 64 bit address translations should never fail.
 	 * 32 bit translations can fail if there are insufficient mapping
 	 * resources.
 	 */

 	*dma_handle = provider->dma_map_consistent(pdev, phys_addr, size,
 						   SN_DMA_ADDR_PHYS);
 	if (!*dma_handle) {
 		printk(KERN_ERR "%s: out of ATEs\n", __func__);
 		free_pages((unsigned long)cpuaddr, get_order(size));
 		return NULL;
 	}

 	return cpuaddr;
 }
 EXPORT_SYMBOL(sn_dma_alloc_coherent);

 /**
  * sn_pci_free_coherent - free memory associated with coherent DMAable region
  * @dev: device to free for
  * @size: size to free
  * @cpu_addr: kernel virtual address to free
  * @dma_handle: DMA address associated with this region
  *
  * Frees the memory allocated by dma_alloc_coherent(), potentially unmapping
  * any associated IOMMU mappings.
  */
 void sn_dma_free_coherent(struct device *dev, size_t size, void *cpu_addr,
 			  dma_addr_t dma_handle)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);

 	BUG_ON(dev->bus != &pci_bus_type);

 	provider->dma_unmap(pdev, dma_handle, 0);
 	free_pages((unsigned long)cpu_addr, get_order(size));
 }
 EXPORT_SYMBOL(sn_dma_free_coherent);

 /**
  * sn_dma_map_single_attrs - map a single page for DMA
  * @dev: device to map for
  * @cpu_addr: kernel virtual address of the region to map
  * @size: size of the region
  * @direction: DMA direction
  * @attrs: optional dma attributes
  *
  * Map the region pointed to by @cpu_addr for DMA and return the
  * DMA address.
  *
  * We map this to the one step pcibr_dmamap_trans interface rather than
  * the two step pcibr_dmamap_alloc/pcibr_dmamap_addr because we have
  * no way of saving the dmamap handle from the alloc to later free
  * (which is pretty much unacceptable).
  *
  * mappings with the DMA_ATTR_WRITE_BARRIER get mapped with
  * dma_map_consistent() so that writes force a flush of pending DMA.
  * (See "SGI Altix Architecture Considerations for Linux Device Drivers",
  * Document Number: 007-4763-001)
  *
  * TODO: simplify our interface;
  *       figure out how to save dmamap handle so can use two step.
  */
 dma_addr_t sn_dma_map_single_attrs(struct device *dev, void *cpu_addr,
 				   size_t size, int direction,
 				   struct dma_attrs *attrs)
 {
 	dma_addr_t dma_addr;
 	unsigned long phys_addr;
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);
 	int dmabarr;

 	dmabarr = dma_get_attr(DMA_ATTR_WRITE_BARRIER, attrs);

 	BUG_ON(dev->bus != &pci_bus_type);

 	phys_addr = __pa(cpu_addr);
 	if (dmabarr)
 		dma_addr = provider->dma_map_consistent(pdev, phys_addr,
 							size, SN_DMA_ADDR_PHYS);
 	else
 		dma_addr = provider->dma_map(pdev, phys_addr, size,
 					     SN_DMA_ADDR_PHYS);

 	if (!dma_addr) {
 		printk(KERN_ERR "%s: out of ATEs\n", __func__);
 		return 0;
 	}
 	return dma_addr;
 }
 EXPORT_SYMBOL(sn_dma_map_single_attrs);

 /**
  * sn_dma_unmap_single_attrs - unamp a DMA mapped page
  * @dev: device to sync
  * @dma_addr: DMA address to sync
  * @size: size of region
  * @direction: DMA direction
  * @attrs: optional dma attributes
  *
  * This routine is supposed to sync the DMA region specified
  * by @dma_handle into the coherence domain.  On SN, we're always cache
  * coherent, so we just need to free any ATEs associated with this mapping.
  */
 void sn_dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
 			       size_t size, int direction,
 			       struct dma_attrs *attrs)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);

 	BUG_ON(dev->bus != &pci_bus_type);

 	provider->dma_unmap(pdev, dma_addr, direction);
 }
 EXPORT_SYMBOL(sn_dma_unmap_single_attrs);

 /**
  * sn_dma_unmap_sg_attrs - unmap a DMA scatterlist
  * @dev: device to unmap
  * @sg: scatterlist to unmap
  * @nhwentries: number of scatterlist entries
  * @direction: DMA direction
  * @attrs: optional dma attributes
  *
  * Unmap a set of streaming mode DMA translations.
  */
 void sn_dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
 			   int nhwentries, int direction,
 			   struct dma_attrs *attrs)
 {
 	int i;
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);
 	struct scatterlist *sg;

 	BUG_ON(dev->bus != &pci_bus_type);

 	for_each_sg(sgl, sg, nhwentries, i) {
 		provider->dma_unmap(pdev, sg->dma_address, direction);
 		sg->dma_address = (dma_addr_t) NULL;
 		sg->dma_length = 0;
 	}
 }
 EXPORT_SYMBOL(sn_dma_unmap_sg_attrs);

 /**
  * sn_dma_map_sg_attrs - map a scatterlist for DMA
  * @dev: device to map for
  * @sg: scatterlist to map
  * @nhwentries: number of entries
  * @direction: direction of the DMA transaction
  * @attrs: optional dma attributes
  *
  * mappings with the DMA_ATTR_WRITE_BARRIER get mapped with
  * dma_map_consistent() so that writes force a flush of pending DMA.
  * (See "SGI Altix Architecture Considerations for Linux Device Drivers",
  * Document Number: 007-4763-001)
  *
  * Maps each entry of @sg for DMA.
  */
 int sn_dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
 			int nhwentries, int direction, struct dma_attrs *attrs)
 {
 	unsigned long phys_addr;
 	struct scatterlist *saved_sg = sgl, *sg;
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);
 	int i;
 	int dmabarr;

 	dmabarr = dma_get_attr(DMA_ATTR_WRITE_BARRIER, attrs);

 	BUG_ON(dev->bus != &pci_bus_type);

 	/*
 	 * Setup a DMA address for each entry in the scatterlist.
 	 */
 	for_each_sg(sgl, sg, nhwentries, i) {
 		dma_addr_t dma_addr;
 		phys_addr = SG_ENT_PHYS_ADDRESS(sg);
 		if (dmabarr)
 			dma_addr = provider->dma_map_consistent(pdev,
 								phys_addr,
 								sg->length,
 								SN_DMA_ADDR_PHYS);
 		else
 			dma_addr = provider->dma_map(pdev, phys_addr,
 						     sg->length,
 						     SN_DMA_ADDR_PHYS);

 		sg->dma_address = dma_addr;
 		if (!sg->dma_address) {
 			printk(KERN_ERR "%s: out of ATEs\n", __func__);

 			/*
 			 * Free any successfully allocated entries.
 			 */
 			if (i > 0)
 				sn_dma_unmap_sg_attrs(dev, saved_sg, i,
 						      direction, attrs);
 			return 0;
 		}

 		sg->dma_length = sg->length;
 	}

 	return nhwentries;
 }
 EXPORT_SYMBOL(sn_dma_map_sg_attrs);

 void sn_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
 				size_t size, int direction)
 {
 	BUG_ON(dev->bus != &pci_bus_type);
 }
 EXPORT_SYMBOL(sn_dma_sync_single_for_cpu);

 void sn_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
 				   size_t size, int direction)
 {
 	BUG_ON(dev->bus != &pci_bus_type);
 }
 EXPORT_SYMBOL(sn_dma_sync_single_for_device);

 void sn_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 			    int nelems, int direction)
 {
 	BUG_ON(dev->bus != &pci_bus_type);
 }
 EXPORT_SYMBOL(sn_dma_sync_sg_for_cpu);

 void sn_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 			       int nelems, int direction)
 {
 	BUG_ON(dev->bus != &pci_bus_type);
 }
 EXPORT_SYMBOL(sn_dma_sync_sg_for_device);

 int sn_dma_mapping_error(dma_addr_t dma_addr)
 {
 	return 0;
 }
 EXPORT_SYMBOL(sn_dma_mapping_error);

 char *sn_pci_get_legacy_mem(struct pci_bus *bus)
 {
 	if (!SN_PCIBUS_BUSSOFT(bus))
 		return ERR_PTR(-ENODEV);

 	return (char *)(SN_PCIBUS_BUSSOFT(bus)->bs_legacy_mem | __IA64_UNCACHED_OFFSET);
 }

 int sn_pci_legacy_read(struct pci_bus *bus, u16 port, u32 *val, u8 size)
 {
 	unsigned long addr;
 	int ret;
 	struct ia64_sal_retval isrv;

 	/*
 	 * First, try the SN_SAL_IOIF_PCI_SAFE SAL call which can work
 	 * around hw issues at the pci bus level.  SGI proms older than
 	 * 4.10 don't implement this.
 	 */

 	SAL_CALL(isrv, SN_SAL_IOIF_PCI_SAFE,
 		 pci_domain_nr(bus), bus->number,
 		 0, /* io */
 		 0, /* read */
 		 port, size, __pa(val));

 	if (isrv.status == 0)
 		return size;

 	/*
 	 * If the above failed, retry using the SAL_PROBE call which should
 	 * be present in all proms (but which cannot work round PCI chipset
 	 * bugs).  This code is retained for compatibility with old
 	 * pre-4.10 proms, and should be removed at some point in the future.
 	 */

 	if (!SN_PCIBUS_BUSSOFT(bus))
 		return -ENODEV;

 	addr = SN_PCIBUS_BUSSOFT(bus)->bs_legacy_io | __IA64_UNCACHED_OFFSET;
 	addr += port;

 	ret = ia64_sn_probe_mem(addr, (long)size, (void *)val);

 	if (ret == 2)
 		return -EINVAL;

 	if (ret == 1)
 		*val = -1;

 	return size;
 }

 int sn_pci_legacy_write(struct pci_bus *bus, u16 port, u32 val, u8 size)
 {
 	int ret = size;
 	unsigned long paddr;
 	unsigned long *addr;
 	struct ia64_sal_retval isrv;

 	/*
 	 * First, try the SN_SAL_IOIF_PCI_SAFE SAL call which can work
 	 * around hw issues at the pci bus level.  SGI proms older than
 	 * 4.10 don't implement this.
 	 */

 	SAL_CALL(isrv, SN_SAL_IOIF_PCI_SAFE,
 		 pci_domain_nr(bus), bus->number,
 		 0, /* io */
 		 1, /* write */
 		 port, size, __pa(&val));

 	if (isrv.status == 0)
 		return size;

 	/*
 	 * If the above failed, retry using the SAL_PROBE call which should
 	 * be present in all proms (but which cannot work round PCI chipset
 	 * bugs).  This code is retained for compatibility with old
 	 * pre-4.10 proms, and should be removed at some point in the future.
 	 */

 	if (!SN_PCIBUS_BUSSOFT(bus)) {
 		ret = -ENODEV;
 		goto out;
 	}

 	/* Put the phys addr in uncached space */
 	paddr = SN_PCIBUS_BUSSOFT(bus)->bs_legacy_io | __IA64_UNCACHED_OFFSET;
 	paddr += port;
 	addr = (unsigned long *)paddr;

 	switch (size) {
 	case 1:
 		*(volatile u8 *)(addr) = (u8)(val);
 		break;
 	case 2:
 		*(volatile u16 *)(addr) = (u16)(val);
 		break;
 	case 4:
 		*(volatile u32 *)(addr) = (u32)(val);
 		break;
 	default:
 		ret = -EINVAL;
 		break;
 	}
  out:
 	return ret;
 }
	/*
	* 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.
	*
	* Copyright (C) 2000,2002-2005 Silicon Graphics, Inc. All rights reserved.
	*
	* Routines for PCI DMA mapping. See Documentation/DMA-API.txt for
	* a description of how these routines should be used.
	*/

	#include <linux/module.h>
	#include <linux/dma-attrs.h>
	#include <asm/dma.h>
	#include <asm/sn/intr.h>
	#include <asm/sn/pcibus_provider_defs.h>
	#include <asm/sn/pcidev.h>
	#include <asm/sn/sn_sal.h>

	#define SG_ENT_VIRT_ADDRESS(sg) (sg_virt((sg)))
	#define SG_ENT_PHYS_ADDRESS(SG) virt_to_phys(SG_ENT_VIRT_ADDRESS(SG))

	/**
	* sn_dma_supported - test a DMA mask
	* @dev: device to test
	* @mask: DMA mask to test
	*
	* Return whether the given PCI device DMA address mask can be supported
	* properly. For example, if your device can only drive the low 24-bits
	* during PCI bus mastering, then you would pass 0x00ffffff as the mask to
	* this function. Of course, SN only supports devices that have 32 or more
	* address bits when using the PMU.
	*/
	int sn_dma_supported(struct device *dev, u64 mask)
	{
	BUG_ON(dev->bus != &pci_bus_type);

	if (mask < 0x7fffffff)
	return 0;
	return 1;
	}
	EXPORT_SYMBOL(sn_dma_supported);

	/**
	* sn_dma_set_mask - set the DMA mask
	* @dev: device to set
	* @dma_mask: new mask
	*
	* Set @dev's DMA mask if the hw supports it.
	*/
	int sn_dma_set_mask(struct device *dev, u64 dma_mask)
	{
	BUG_ON(dev->bus != &pci_bus_type);

	if (!sn_dma_supported(dev, dma_mask))
	return 0;

	*dev->dma_mask = dma_mask;
	return 1;
	}
	EXPORT_SYMBOL(sn_dma_set_mask);

	/**
	* sn_dma_alloc_coherent - allocate memory for coherent DMA
	* @dev: device to allocate for
	* @size: size of the region
	* @dma_handle: DMA (bus) address
	* @flags: memory allocation flags
	*
	* dma_alloc_coherent() returns a pointer to a memory region suitable for
	* coherent DMA traffic to/from a PCI device. On SN platforms, this means
	* that @dma_handle will have the %PCIIO_DMA_CMD flag set.
	*
	* This interface is usually used for "command" streams (e.g. the command
	* queue for a SCSI controller). See Documentation/DMA-API.txt for
	* more information.
	*/
	void sn_dma_alloc_coherent(struct device dev, size_t size,
	dma_addr_t * dma_handle, gfp_t flags)
	{
	void *cpuaddr;
	unsigned long phys_addr;
	int node;
	struct pci_dev *pdev = to_pci_dev(dev);
	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);

	BUG_ON(dev->bus != &pci_bus_type);

	/*
	* Allocate the memory.
	*/
	node = pcibus_to_node(pdev->bus);
	if (likely(node >=0)) {
	struct page *p = alloc_pages_node(node, flags, get_order(size));

	if (likely(p))
	cpuaddr = page_address(p);
	else
	return NULL;
	} else
	cpuaddr = (void *)__get_free_pages(flags, get_order(size));

	if (unlikely(!cpuaddr))
	return NULL;

	memset(cpuaddr, 0x0, size);

	/* physical addr. of the memory we just got */
	phys_addr = __pa(cpuaddr);

	/*
	* 64 bit address translations should never fail.
	* 32 bit translations can fail if there are insufficient mapping
	* resources.
	*/

	*dma_handle = provider->dma_map_consistent(pdev, phys_addr, size,
	SN_DMA_ADDR_PHYS);
	if (!*dma_handle) {
	printk(KERN_ERR "%s: out of ATEs\n", __func__);
	free_pages((unsigned long)cpuaddr, get_order(size));
	return NULL;
	}

	return cpuaddr;
	}
	EXPORT_SYMBOL(sn_dma_alloc_coherent);

	/**
	* sn_pci_free_coherent - free memory associated with coherent DMAable region
	* @dev: device to free for
	* @size: size to free
	* @cpu_addr: kernel virtual address to free
	* @dma_handle: DMA address associated with this region
	*
	* Frees the memory allocated by dma_alloc_coherent(), potentially unmapping
	* any associated IOMMU mappings.
	*/
	void sn_dma_free_coherent(struct device dev, size_t size, void cpu_addr,
	dma_addr_t dma_handle)
	{
	struct pci_dev *pdev = to_pci_dev(dev);
	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);

	BUG_ON(dev->bus != &pci_bus_type);

	provider->dma_unmap(pdev, dma_handle, 0);
	free_pages((unsigned long)cpu_addr, get_order(size));
	}
	EXPORT_SYMBOL(sn_dma_free_coherent);

	/**
	* sn_dma_map_single_attrs - map a single page for DMA
	* @dev: device to map for
	* @cpu_addr: kernel virtual address of the region to map
	* @size: size of the region
	* @direction: DMA direction
	* @attrs: optional dma attributes
	*
	* Map the region pointed to by @cpu_addr for DMA and return the
	* DMA address.
	*
	* We map this to the one step pcibr_dmamap_trans interface rather than
	* the two step pcibr_dmamap_alloc/pcibr_dmamap_addr because we have
	* no way of saving the dmamap handle from the alloc to later free
	* (which is pretty much unacceptable).
	*
	* mappings with the DMA_ATTR_WRITE_BARRIER get mapped with
	* dma_map_consistent() so that writes force a flush of pending DMA.
	* (See "SGI Altix Architecture Considerations for Linux Device Drivers",
	* Document Number: 007-4763-001)
	*
	* TODO: simplify our interface;
	* figure out how to save dmamap handle so can use two step.
	*/
	dma_addr_t sn_dma_map_single_attrs(struct device dev, void cpu_addr,
	size_t size, int direction,
	struct dma_attrs *attrs)
	{
	dma_addr_t dma_addr;
	unsigned long phys_addr;
	struct pci_dev *pdev = to_pci_dev(dev);
	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);
	int dmabarr;

	dmabarr = dma_get_attr(DMA_ATTR_WRITE_BARRIER, attrs);

	BUG_ON(dev->bus != &pci_bus_type);

	phys_addr = __pa(cpu_addr);
	if (dmabarr)
	dma_addr = provider->dma_map_consistent(pdev, phys_addr,
	size, SN_DMA_ADDR_PHYS);
	else
	dma_addr = provider->dma_map(pdev, phys_addr, size,
	SN_DMA_ADDR_PHYS);

	if (!dma_addr) {
	printk(KERN_ERR "%s: out of ATEs\n", __func__);
	return 0;
	}
	return dma_addr;
	}
	EXPORT_SYMBOL(sn_dma_map_single_attrs);

	/**
	* sn_dma_unmap_single_attrs - unamp a DMA mapped page
	* @dev: device to sync
	* @dma_addr: DMA address to sync
	* @size: size of region
	* @direction: DMA direction
	* @attrs: optional dma attributes
	*
	* This routine is supposed to sync the DMA region specified
	* by @dma_handle into the coherence domain. On SN, we're always cache
	* coherent, so we just need to free any ATEs associated with this mapping.
	*/
	void sn_dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
	size_t size, int direction,
	struct dma_attrs *attrs)
	{
	struct pci_dev *pdev = to_pci_dev(dev);
	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);

	BUG_ON(dev->bus != &pci_bus_type);

	provider->dma_unmap(pdev, dma_addr, direction);
	}
	EXPORT_SYMBOL(sn_dma_unmap_single_attrs);

	/**
	* sn_dma_unmap_sg_attrs - unmap a DMA scatterlist
	* @dev: device to unmap
	* @sg: scatterlist to unmap
	* @nhwentries: number of scatterlist entries
	* @direction: DMA direction
	* @attrs: optional dma attributes
	*
	* Unmap a set of streaming mode DMA translations.
	*/
	void sn_dma_unmap_sg_attrs(struct device dev, struct scatterlist sgl,
	int nhwentries, int direction,
	struct dma_attrs *attrs)
	{
	int i;
	struct pci_dev *pdev = to_pci_dev(dev);
	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);
	struct scatterlist *sg;

	BUG_ON(dev->bus != &pci_bus_type);

	for_each_sg(sgl, sg, nhwentries, i) {
	provider->dma_unmap(pdev, sg->dma_address, direction);
	sg->dma_address = (dma_addr_t) NULL;
	sg->dma_length = 0;
	}
	}
	EXPORT_SYMBOL(sn_dma_unmap_sg_attrs);

	/**
	* sn_dma_map_sg_attrs - map a scatterlist for DMA
	* @dev: device to map for
	* @sg: scatterlist to map
	* @nhwentries: number of entries
	* @direction: direction of the DMA transaction
	* @attrs: optional dma attributes
	*
	* mappings with the DMA_ATTR_WRITE_BARRIER get mapped with
	* dma_map_consistent() so that writes force a flush of pending DMA.
	* (See "SGI Altix Architecture Considerations for Linux Device Drivers",
	* Document Number: 007-4763-001)
	*
	* Maps each entry of @sg for DMA.
	*/
	int sn_dma_map_sg_attrs(struct device dev, struct scatterlist sgl,
	int nhwentries, int direction, struct dma_attrs *attrs)
	{
	unsigned long phys_addr;
	struct scatterlist saved_sg = sgl, sg;
	struct pci_dev *pdev = to_pci_dev(dev);
	struct sn_pcibus_provider *provider = SN_PCIDEV_BUSPROVIDER(pdev);
	int i;
	int dmabarr;

	dmabarr = dma_get_attr(DMA_ATTR_WRITE_BARRIER, attrs);

	BUG_ON(dev->bus != &pci_bus_type);

	/*
	* Setup a DMA address for each entry in the scatterlist.
	*/
	for_each_sg(sgl, sg, nhwentries, i) {
	dma_addr_t dma_addr;
	phys_addr = SG_ENT_PHYS_ADDRESS(sg);
	if (dmabarr)
	dma_addr = provider->dma_map_consistent(pdev,
	phys_addr,
	sg->length,
	SN_DMA_ADDR_PHYS);
	else
	dma_addr = provider->dma_map(pdev, phys_addr,
	sg->length,
	SN_DMA_ADDR_PHYS);

	sg->dma_address = dma_addr;
	if (!sg->dma_address) {
	printk(KERN_ERR "%s: out of ATEs\n", __func__);

	/*
	* Free any successfully allocated entries.
	*/
	if (i > 0)
	sn_dma_unmap_sg_attrs(dev, saved_sg, i,
	direction, attrs);
	return 0;
	}

	sg->dma_length = sg->length;
	}

	return nhwentries;
	}
	EXPORT_SYMBOL(sn_dma_map_sg_attrs);

	void sn_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
	size_t size, int direction)
	{
	BUG_ON(dev->bus != &pci_bus_type);
	}
	EXPORT_SYMBOL(sn_dma_sync_single_for_cpu);

	void sn_dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
	size_t size, int direction)
	{
	BUG_ON(dev->bus != &pci_bus_type);
	}
	EXPORT_SYMBOL(sn_dma_sync_single_for_device);

	void sn_dma_sync_sg_for_cpu(struct device dev, struct scatterlist sg,
	int nelems, int direction)
	{
	BUG_ON(dev->bus != &pci_bus_type);
	}
	EXPORT_SYMBOL(sn_dma_sync_sg_for_cpu);

	void sn_dma_sync_sg_for_device(struct device dev, struct scatterlist sg,
	int nelems, int direction)
	{
	BUG_ON(dev->bus != &pci_bus_type);
	}
	EXPORT_SYMBOL(sn_dma_sync_sg_for_device);

	int sn_dma_mapping_error(dma_addr_t dma_addr)
	{
	return 0;
	}
	EXPORT_SYMBOL(sn_dma_mapping_error);

	char sn_pci_get_legacy_mem(struct pci_bus bus)
	{
	if (!SN_PCIBUS_BUSSOFT(bus))
	return ERR_PTR(-ENODEV);

	return (char *)(SN_PCIBUS_BUSSOFT(bus)->bs_legacy_mem \| __IA64_UNCACHED_OFFSET);
	}

	int sn_pci_legacy_read(struct pci_bus bus, u16 port, u32 val, u8 size)
	{
	unsigned long addr;
	int ret;
	struct ia64_sal_retval isrv;

	/*
	* First, try the SN_SAL_IOIF_PCI_SAFE SAL call which can work
	* around hw issues at the pci bus level. SGI proms older than
	* 4.10 don't implement this.
	*/

	SAL_CALL(isrv, SN_SAL_IOIF_PCI_SAFE,
	pci_domain_nr(bus), bus->number,
	0, /* io */
	0, /* read */
	port, size, __pa(val));

	if (isrv.status == 0)
	return size;

	/*
	* If the above failed, retry using the SAL_PROBE call which should
	* be present in all proms (but which cannot work round PCI chipset
	* bugs). This code is retained for compatibility with old
	* pre-4.10 proms, and should be removed at some point in the future.
	*/

	if (!SN_PCIBUS_BUSSOFT(bus))
	return -ENODEV;

	addr = SN_PCIBUS_BUSSOFT(bus)->bs_legacy_io \| __IA64_UNCACHED_OFFSET;
	addr += port;

	ret = ia64_sn_probe_mem(addr, (long)size, (void *)val);

	if (ret == 2)
	return -EINVAL;

	if (ret == 1)
	*val = -1;

	return size;
	}

	int sn_pci_legacy_write(struct pci_bus *bus, u16 port, u32 val, u8 size)
	{
	int ret = size;
	unsigned long paddr;
	unsigned long *addr;
	struct ia64_sal_retval isrv;

	/*
	* First, try the SN_SAL_IOIF_PCI_SAFE SAL call which can work
	* around hw issues at the pci bus level. SGI proms older than
	* 4.10 don't implement this.
	*/

	SAL_CALL(isrv, SN_SAL_IOIF_PCI_SAFE,
	pci_domain_nr(bus), bus->number,
	0, /* io */
	1, /* write */
	port, size, __pa(&val));

	if (isrv.status == 0)
	return size;

	/*
	* If the above failed, retry using the SAL_PROBE call which should
	* be present in all proms (but which cannot work round PCI chipset
	* bugs). This code is retained for compatibility with old
	* pre-4.10 proms, and should be removed at some point in the future.
	*/

	if (!SN_PCIBUS_BUSSOFT(bus)) {
	ret = -ENODEV;
	goto out;
	}

	/* Put the phys addr in uncached space */
	paddr = SN_PCIBUS_BUSSOFT(bus)->bs_legacy_io \| __IA64_UNCACHED_OFFSET;
	paddr += port;
	addr = (unsigned long *)paddr;

	switch (size) {
	case 1:
	(volatile u8 )(addr) = (u8)(val);
	break;
	case 2:
	(volatile u16 )(addr) = (u16)(val);
	break;
	case 4:
	(volatile u32 )(addr) = (u32)(val);
	break;
	default:
	ret = -EINVAL;
	break;
	}
	out:
	return ret;
	}