pci_dma.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

	/* can't go anywhere w/o a direction in life */
	if (direction == PCI_DMA_NONE)
		BUG();

	/*
	 * Get the hwgraph vertex for the device
	 */
	device_sysdata = (struct sn_device_sysdata *) hwdev->sysdata;
	vhdl = device_sysdata->vhdl;

	/*
	 * Setup a DMA address for each entry in the
	 * scatterlist.
	 */
	for (i = 0; i < nents; i++, sg++) {
		/* this catches incorrectly written drivers that
                   attempt to map scatterlists that they have
                   previously mapped.  we print a warning and
                   continue, but the driver should be fixed */
#ifdef DEBUG
		if (sg->dma_address) {
/* This needs to be cleaned up at some point. */
			NAG("A PCI driver (for device at%8s) has attempted to "
			    "map a scatterlist that was previously mapped at "
			    "%p - this is currently being worked around.\n",
			    hwdev->slot_name, (void *)sg->dma_address);
			phys_addr = (u64)sg->dma_address & TO_PHYS_MASK;
		} else
#endif
			phys_addr = __pa(sg->address ? sg->address :
					page_address(sg->page) + offset);

		/*
		 * Handle the most common case: 64 bit cards.  This
		 * call should always succeed.
		 */
		if (IS_PCIA64(hwdev)) {
			sg->dma_address = pciio_dmatrans_addr(vhdl, NULL, phys_addr,
						       sg->length,
						       DMA_DATA_FLAGS | PCIIO_DMA_A64 );
			sg->dma_length = sg->length;
			continue;
		}

		/*
		 * Handle 32-63 bit cards via direct mapping
		 */
		if (IS_PCI32G(hwdev)) {
			sg->dma_address = pciio_dmatrans_addr(vhdl, NULL,
								phys_addr,
								sg->length,
								DMA_DATA_FLAGS);
			sg->dma_length = sg->length;

			if (sg->dma_address)
				continue;

		}

		/*
		 * It is a 32 bit card and we cannot do direct mapping,
		 * so we use an ATE.
		 */
		dma_map = 0;
		dma_map = pciio_dmamap_alloc(vhdl, NULL, sg->length,
					     DMA_DATA_FLAGS);
		if (!dma_map) {
			printk(KERN_ERR "sn_pci_map_sg: Unable to allocate "
			       "anymore 32 bit page map entries.\n");
			BUG();
		}
		sg->dma_address = pciio_dmamap_addr(dma_map, phys_addr, sg->length);
		sg->dma_length = sg->length;
#warning BADBADBAD scsi retries will die since sglist is unmapped and reused.
		sg->page = (char *)dma_map;
	}

	return nents;

}

/**
 * sn_pci_unmap_sg - unmap a scatter-gather list
 * @hwdev: device to unmap
 * @sg: scatterlist to unmap
 * @nents: number of scatterlist entries
 * @direction: DMA direction
 *
 * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
 * concerning calls here are the same as for pci_unmap_single() below.  Also
 * known as sn_pci_unmap_sg() by the IA64 machvec code.
 */
void
sn_pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist *sg, int nents, int direction)
{
	int i;

	/* can't go anywhere w/o a direction in life */
	if (direction == PCI_DMA_NONE)
		BUG();

	for (i = 0; i < nents; i++, sg++)
#warning need to derive sn_dma_map from sg->dma_address instead
		if (sg->page) {
			struct sn_dma_maps_s *sn_dma_map;
			/*
			 * We maintain the DMA Map pointer in sg->page if 
			 * it is ever allocated.
			 */
			sg->dma_address = 0;
			sn_dma_map = (struct sn_dma_maps_s *)sg->page;
			pciio_dmamap_done((pciio_dmamap_t)sn_dma_map);
			pciio_dmamap_free((pciio_dmamap_t)sn_dma_map);
			sn_dma_map->dma_addr = 0;
			sg->page = 0;
		}

}

/**
 * sn_pci_map_single - map a single region for DMA
 * @hwdev: device to map for
 * @ptr: kernel virtual address of the region to map
 * @size: size of the region
 * @direction: DMA direction
 *
 * Map the region pointed to by @ptr for DMA and return the
 * DMA address.   Also known as platform_pci_map_single() by
 * the IA64 machvec code.
 *
 * We map this to the one step pciio_dmamap_trans interface rather than
 * the two step pciio_dmamap_alloc/pciio_dmamap_addr because we have
 * no way of saving the dmamap handle from the alloc to later free
 * (which is pretty much unacceptable).
 *
 * TODO: simplify our interface;
 *       get rid of dev_desc and vhdl (seems redundant given a pci_dev);
 *       figure out how to save dmamap handle so can use two step.
 */
dma_addr_t
sn_pci_map_single(struct pci_dev *hwdev, void *ptr, size_t size, int direction)
{
	devfs_handle_t vhdl;
	dma_addr_t dma_addr;
	unsigned long phys_addr;
	struct sn_device_sysdata *device_sysdata;
	pciio_dmamap_t dma_map = NULL;
	struct sn_dma_maps_s *sn_dma_map;

	if (direction == PCI_DMA_NONE)
		BUG();

	/* SN cannot support DMA addresses smaller than 32 bits. */
	if (IS_PCI32L(hwdev)) return 0;

	/*
	 * find vertex for the device
	 */
	device_sysdata = (struct sn_device_sysdata *)hwdev->sysdata;
	vhdl = device_sysdata->vhdl;

	/*
	 * Call our dmamap interface
	 */
	dma_addr = 0;
	phys_addr = __pa(ptr);

	if (IS_PCIA64(hwdev)) {
		/*
		 * This device supports 64 bit DMA addresses.
		 */
		dma_addr = pciio_dmatrans_addr(vhdl, NULL, phys_addr, size,
					       DMA_DATA_FLAGS | PCIIO_DMA_A64);
		return dma_addr;
	}

	/*
	 * Devices that supports 32 bit to 63 bit DMA addresses get
	 * 32 bit DMA addresses.
	 *
	 * First try to get a 32 bit direct map register.
	 */
	if (IS_PCI32G(hwdev)) {
		dma_addr = pciio_dmatrans_addr(vhdl, NULL, phys_addr, size,
					       DMA_DATA_FLAGS);
		if (dma_addr)
			return dma_addr;
	}

	/*
	 * It's a 32 bit card and we cannot do direct mapping so
	 * let's use the PMU instead.
	 */
	dma_map = NULL;
	dma_map = pciio_dmamap_alloc(vhdl, NULL, size, DMA_DATA_FLAGS);

	if (!dma_map) {
		printk(KERN_ERR "pci_map_single: Unable to allocate anymore "
		       "32 bits page map entries.\n");
		BUG();
	}

	dma_addr = (dma_addr_t) pciio_dmamap_addr(dma_map, phys_addr, size);
	sn_dma_map = (struct sn_dma_maps_s *)dma_map;
	sn_dma_map->dma_addr = dma_addr;

	return ((dma_addr_t)dma_addr);
}

/**
 * sn_pci_unmap_single - unmap a region used for DMA
 * @hwdev: device to unmap
 * @dma_addr: DMA address to unmap
 * @size: size of region
 * @direction: DMA direction
 *
 * Unmaps the region pointed to by @dma_addr.  Also known as
 * platform_pci_unmap_single() by the IA64 machvec code.
 */
void
sn_pci_unmap_single(struct pci_dev *hwdev, dma_addr_t dma_addr, size_t size, int direction)
{
	struct sn_dma_maps_s *sn_dma_map = NULL;

        if (direction == PCI_DMA_NONE)
		BUG();

	/*
	 * Get the sn_dma_map entry.
	 */
	if (IS_PCI32_MAPPED(dma_addr))
		sn_dma_map = find_sn_dma_map(dma_addr, hwdev->bus->number);

	/*
	 * and free it if necessary...
	 */
	if (sn_dma_map) {
		pciio_dmamap_done((pciio_dmamap_t)sn_dma_map);
		pciio_dmamap_free((pciio_dmamap_t)sn_dma_map);
		sn_dma_map->dma_addr = (dma_addr_t)NULL;
	}
}

/**
 * sn_pci_dma_sync_single - make sure all DMAs have completed
 * @hwdev: device to sync
 * @dma_handle: DMA address to sync
 * @size: size of region
 * @direction: DMA direction
 *
 * This routine is supposed to sync the DMA region specified
 * by @dma_handle into the 'coherence domain'.  See sn_dma_sync()
 * above for more information.   Also known as
 * platform_pci_dma_sync_single() by the IA64 machvec code.
 */
void
sn_pci_dma_sync_single(struct pci_dev *hwdev, dma_addr_t dma_handle, size_t size, int direction)
{
	if (direction == PCI_DMA_NONE)
                BUG();

	sn_dma_sync(hwdev);
}

/**
 * sn_pci_dma_sync_sg - make sure all DMAs have completed
 * @hwdev: device to sync
 * @sg: scatterlist to sync
 * @nents: number of entries in the scatterlist
 * @direction: DMA direction
 *
 * This routine is supposed to sync the DMA regions specified
 * by @sg into the 'coherence domain'.  See sn_dma_sync()
 * above for more information.   Also known as
 * platform_pci_dma_sync_sg() by the IA64 machvec code.
 */
void
sn_pci_dma_sync_sg(struct pci_dev *hwdev, struct scatterlist *sg, int nents, int direction)
{
        if (direction == PCI_DMA_NONE)
                BUG();

	sn_dma_sync(hwdev);
}

/**
 * sn_dma_supported - test a DMA mask
 * @hwdev: 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.
 */
int
sn_pci_dma_supported(struct pci_dev *hwdev, u64 mask)
{
	if (mask < 0xffffffff)
		return 0;
	return 1;
}

EXPORT_SYMBOL(sn_pci_unmap_single);
EXPORT_SYMBOL(sn_pci_map_single);
EXPORT_SYMBOL(sn_pci_dma_sync_single);
EXPORT_SYMBOL(sn_pci_map_sg);
EXPORT_SYMBOL(sn_pci_unmap_sg);
EXPORT_SYMBOL(sn_pci_alloc_consistent);
EXPORT_SYMBOL(sn_pci_free_consistent);
EXPORT_SYMBOL(sn_pci_dma_supported);