PCI: remove pci_dac_dma_... APIs

Based on replies to a respective query, remove the pci_dac_dma_...() APIs
(except for pci_dac_dma_supported() on Alpha, where this function is used
in non-DAC PCI DMA code).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Jesse Barnes <jesse.barnes@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Acked-by: David Miller <davem@davemloft.net>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 0 insertions, 103 deletions

diff --git a/Documentation/DMA-mapping.txt b/Documentation/DMA-mapping.txt
index 028614cdd062..e07f2530326b 100644
--- a/Documentation/DMA-mapping.txt
+++ b/Documentation/DMA-mapping.txt
@@ -664,109 +664,6 @@ It is that simple.
 Well, not for some odd devices.  See the next section for information
 about that.
 
-        DAC Addressing for Address Space Hungry Devices
-
-There exists a class of devices which do not mesh well with the PCI
-DMA mapping API.  By definition these "mappings" are a finite
-resource.  The number of total available mappings per bus is platform
-specific, but there will always be a reasonable amount.
-
-What is "reasonable"?  Reasonable means that networking and block I/O
-devices need not worry about using too many mappings.
-
-As an example of a problematic device, consider compute cluster cards.
-They can potentially need to access gigabytes of memory at once via
-DMA.  Dynamic mappings are unsuitable for this kind of access pattern.
-
-To this end we've provided a small API by which a device driver
-may use DAC cycles to directly address all of physical memory.
-Not all platforms support this, but most do.  It is easy to determine
-whether the platform will work properly at probe time.
-
-First, understand that there may be a SEVERE performance penalty for
-using these interfaces on some platforms.  Therefore, you MUST only
-use these interfaces if it is absolutely required.  %99 of devices can
-use the normal APIs without any problems.
-
-Note that for streaming type mappings you must either use these
-interfaces, or the dynamic mapping interfaces above.  You may not mix
-usage of both for the same device.  Such an act is illegal and is
-guaranteed to put a banana in your tailpipe.
-
-However, consistent mappings may in fact be used in conjunction with
-these interfaces.  Remember that, as defined, consistent mappings are
-always going to be SAC addressable.
-
-The first thing your driver needs to do is query the PCI platform
-layer if it is capable of handling your devices DAC addressing
-capabilities:
-
-        int pci_dac_dma_supported(struct pci_dev *hwdev, u64 mask);
-
-You may not use the following interfaces if this routine fails.
-
-Next, DMA addresses using this API are kept track of using the
-dma64_addr_t type.  It is guaranteed to be big enough to hold any
-DAC address the platform layer will give to you from the following
-routines.  If you have consistent mappings as well, you still
-use plain dma_addr_t to keep track of those.
-
-All mappings obtained here will be direct.  The mappings are not
-translated, and this is the purpose of this dialect of the DMA API.
-
-All routines work with page/offset pairs.  This is the _ONLY_ way to 
-portably refer to any piece of memory.  If you have a cpu pointer
-(which may be validly DMA'd too) you may easily obtain the page
-and offset using something like this:
-
-        struct page *page = virt_to_page(ptr);
-        unsigned long offset = offset_in_page(ptr);
-
-Here are the interfaces:
-
-        dma64_addr_t pci_dac_page_to_dma(struct pci_dev *pdev,
-                                         struct page *page,
-                                         unsigned long offset,
-                                         int direction);
-
-The DAC address for the tuple PAGE/OFFSET are returned.  The direction
-argument is the same as for pci_{map,unmap}_single().  The same rules
-for cpu/device access apply here as for the streaming mapping
-interfaces.  To reiterate:
-
-        The cpu may touch the buffer before pci_dac_page_to_dma.
-        The device may touch the buffer after pci_dac_page_to_dma
-        is made, but the cpu may NOT.
-
-When the DMA transfer is complete, invoke:
-
-        void pci_dac_dma_sync_single_for_cpu(struct pci_dev *pdev,
-                                             dma64_addr_t dma_addr,
-                                             size_t len, int direction);
-
-This must be done before the CPU looks at the buffer again.
-This interface behaves identically to pci_dma_sync_{single,sg}_for_cpu().
-
-And likewise, if you wish to let the device get back at the buffer after
-the cpu has read/written it, invoke:
-
-        void pci_dac_dma_sync_single_for_device(struct pci_dev *pdev,
-                                                dma64_addr_t dma_addr,
-                                                size_t len, int direction);
-
-before letting the device access the DMA area again.
-
-If you need to get back to the PAGE/OFFSET tuple from a dma64_addr_t
-the following interfaces are provided:
-
-        struct page *pci_dac_dma_to_page(struct pci_dev *pdev,
-                                         dma64_addr_t dma_addr);
-        unsigned long pci_dac_dma_to_offset(struct pci_dev *pdev,
-                                            dma64_addr_t dma_addr);
-
-This is possible with the DAC interfaces purely because they are
-not translated in any way.
-
                 Optimizing Unmap State Space Consumption
 
 On many platforms, pci_unmap_{single,page}() is simply a nop.