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r: 191551
b: refs/heads/master
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h: refs/heads/master
i:
  191549: 151bfb8
  191547: b904eed
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Jack Steiner authored and Ingo Molnar committed Mar 11, 2010
1 parent b040f4e commit 8d034df
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2 changes: 1 addition & 1 deletion [refs]
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@@ -1,2 +1,2 @@
---
refs/heads/master: 3ae684e1c48e6deedc9b9faff8fa1c391ca8a652
refs/heads/master: 6f4edd69e40aba4f45bf9558c1e9a950d79ab4e4
20 changes: 8 additions & 12 deletions trunk/.gitignore
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Expand Up @@ -34,18 +34,14 @@ modules.builtin
#
# Top-level generic files
#
/tags
/TAGS
/linux
/vmlinux
/vmlinuz
/System.map
/Module.markers
/Module.symvers

#
# git files that we don't want to ignore even it they are dot-files
#
tags
TAGS
linux
vmlinux
vmlinuz
System.map
Module.markers
Module.symvers
!.gitignore
!.mailmap

Expand Down
2 changes: 1 addition & 1 deletion trunk/Documentation/ABI/testing/sysfs-bus-usb
Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,7 @@ Description:
match the driver to the device. For example:
# echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id

What: /sys/bus/usb/device/.../avoid_reset_quirk
What: /sys/bus/usb/device/.../avoid_reset
Date: December 2009
Contact: Oliver Neukum <oliver@neukum.org>
Description:
Expand Down
122 changes: 86 additions & 36 deletions trunk/Documentation/DMA-API.txt
Original file line number Diff line number Diff line change
Expand Up @@ -4,18 +4,20 @@
James E.J. Bottomley <James.Bottomley@HansenPartnership.com>

This document describes the DMA API. For a more gentle introduction
of the API (and actual examples) see
Documentation/DMA-API-HOWTO.txt.
phrased in terms of the pci_ equivalents (and actual examples) see
Documentation/PCI/PCI-DMA-mapping.txt.

This API is split into two pieces. Part I describes the API. Part II
describes the extensions to the API for supporting non-consistent
memory machines. Unless you know that your driver absolutely has to
support non-consistent platforms (this is usually only legacy
platforms) you should only use the API described in part I.
This API is split into two pieces. Part I describes the API and the
corresponding pci_ API. Part II describes the extensions to the API
for supporting non-consistent memory machines. Unless you know that
your driver absolutely has to support non-consistent platforms (this
is usually only legacy platforms) you should only use the API
described in part I.

Part I - dma_ API
Part I - pci_ and dma_ Equivalent API
-------------------------------------

To get the pci_ API, you must #include <linux/pci.h>
To get the dma_ API, you must #include <linux/dma-mapping.h>


Expand All @@ -25,6 +27,9 @@ Part Ia - Using large dma-coherent buffers
void *
dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag)
void *
pci_alloc_consistent(struct pci_dev *dev, size_t size,
dma_addr_t *dma_handle)

Consistent memory is memory for which a write by either the device or
the processor can immediately be read by the processor or device
Expand All @@ -48,11 +53,15 @@ The simplest way to do that is to use the dma_pool calls (see below).
The flag parameter (dma_alloc_coherent only) allows the caller to
specify the GFP_ flags (see kmalloc) for the allocation (the
implementation may choose to ignore flags that affect the location of
the returned memory, like GFP_DMA).
the returned memory, like GFP_DMA). For pci_alloc_consistent, you
must assume GFP_ATOMIC behaviour.

void
dma_free_coherent(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_handle)
void
pci_free_consistent(struct pci_dev *dev, size_t size, void *cpu_addr,
dma_addr_t dma_handle)

Free the region of consistent memory you previously allocated. dev,
size and dma_handle must all be the same as those passed into the
Expand Down Expand Up @@ -80,6 +89,10 @@ for alignment, like queue heads needing to be aligned on N-byte boundaries.
dma_pool_create(const char *name, struct device *dev,
size_t size, size_t align, size_t alloc);

struct pci_pool *
pci_pool_create(const char *name, struct pci_device *dev,
size_t size, size_t align, size_t alloc);

The pool create() routines initialize a pool of dma-coherent buffers
for use with a given device. It must be called in a context which
can sleep.
Expand All @@ -95,6 +108,9 @@ from this pool must not cross 4KByte boundaries.
void *dma_pool_alloc(struct dma_pool *pool, gfp_t gfp_flags,
dma_addr_t *dma_handle);

void *pci_pool_alloc(struct pci_pool *pool, gfp_t gfp_flags,
dma_addr_t *dma_handle);

This allocates memory from the pool; the returned memory will meet the size
and alignment requirements specified at creation time. Pass GFP_ATOMIC to
prevent blocking, or if it's permitted (not in_interrupt, not holding SMP locks),
Expand All @@ -106,13 +122,18 @@ pool's device.
void dma_pool_free(struct dma_pool *pool, void *vaddr,
dma_addr_t addr);

void pci_pool_free(struct pci_pool *pool, void *vaddr,
dma_addr_t addr);

This puts memory back into the pool. The pool is what was passed to
the pool allocation routine; the cpu (vaddr) and dma addresses are what
were returned when that routine allocated the memory being freed.


void dma_pool_destroy(struct dma_pool *pool);

void pci_pool_destroy(struct pci_pool *pool);

The pool destroy() routines free the resources of the pool. They must be
called in a context which can sleep. Make sure you've freed all allocated
memory back to the pool before you destroy it.
Expand All @@ -123,6 +144,8 @@ Part Ic - DMA addressing limitations

int
dma_supported(struct device *dev, u64 mask)
int
pci_dma_supported(struct pci_dev *hwdev, u64 mask)

Checks to see if the device can support DMA to the memory described by
mask.
Expand All @@ -136,14 +159,8 @@ driver writers.

int
dma_set_mask(struct device *dev, u64 mask)

Checks to see if the mask is possible and updates the device
parameters if it is.

Returns: 0 if successful and a negative error if not.

int
dma_set_coherent_mask(struct device *dev, u64 mask)
pci_set_dma_mask(struct pci_device *dev, u64 mask)

Checks to see if the mask is possible and updates the device
parameters if it is.
Expand All @@ -170,6 +187,9 @@ Part Id - Streaming DMA mappings
dma_addr_t
dma_map_single(struct device *dev, void *cpu_addr, size_t size,
enum dma_data_direction direction)
dma_addr_t
pci_map_single(struct pci_dev *hwdev, void *cpu_addr, size_t size,
int direction)

Maps a piece of processor virtual memory so it can be accessed by the
device and returns the physical handle of the memory.
Expand All @@ -178,10 +198,14 @@ The direction for both api's may be converted freely by casting.
However the dma_ API uses a strongly typed enumerator for its
direction:

DMA_NONE no direction (used for debugging)
DMA_TO_DEVICE data is going from the memory to the device
DMA_FROM_DEVICE data is coming from the device to the memory
DMA_BIDIRECTIONAL direction isn't known
DMA_NONE = PCI_DMA_NONE no direction (used for
debugging)
DMA_TO_DEVICE = PCI_DMA_TODEVICE data is going from the
memory to the device
DMA_FROM_DEVICE = PCI_DMA_FROMDEVICE data is coming from
the device to the
memory
DMA_BIDIRECTIONAL = PCI_DMA_BIDIRECTIONAL direction isn't known

Notes: Not all memory regions in a machine can be mapped by this
API. Further, regions that appear to be physically contiguous in
Expand Down Expand Up @@ -244,6 +268,9 @@ cache lines are updated with data that the device may have changed).
void
dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
enum dma_data_direction direction)
void
pci_unmap_single(struct pci_dev *hwdev, dma_addr_t dma_addr,
size_t size, int direction)

Unmaps the region previously mapped. All the parameters passed in
must be identical to those passed in (and returned) by the mapping
Expand All @@ -253,9 +280,15 @@ dma_addr_t
dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction direction)
dma_addr_t
pci_map_page(struct pci_dev *hwdev, struct page *page,
unsigned long offset, size_t size, int direction)
void
dma_unmap_page(struct device *dev, dma_addr_t dma_address, size_t size,
enum dma_data_direction direction)
void
pci_unmap_page(struct pci_dev *hwdev, dma_addr_t dma_address,
size_t size, int direction)

API for mapping and unmapping for pages. All the notes and warnings
for the other mapping APIs apply here. Also, although the <offset>
Expand All @@ -266,6 +299,9 @@ cache width is.
int
dma_mapping_error(struct device *dev, dma_addr_t dma_addr)

int
pci_dma_mapping_error(struct pci_dev *hwdev, dma_addr_t dma_addr)

In some circumstances dma_map_single and dma_map_page will fail to create
a mapping. A driver can check for these errors by testing the returned
dma address with dma_mapping_error(). A non-zero return value means the mapping
Expand All @@ -275,6 +311,9 @@ reduce current DMA mapping usage or delay and try again later).
int
dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction direction)
int
pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg,
int nents, int direction)

Returns: the number of physical segments mapped (this may be shorter
than <nents> passed in if some elements of the scatter/gather list are
Expand Down Expand Up @@ -314,6 +353,9 @@ accessed sg->address and sg->length as shown above.
void
dma_unmap_sg(struct device *dev, struct scatterlist *sg,
int nhwentries, enum dma_data_direction direction)
void
pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist *sg,
int nents, int direction)

Unmap the previously mapped scatter/gather list. All the parameters
must be the same as those and passed in to the scatter/gather mapping
Expand All @@ -323,23 +365,21 @@ Note: <nents> must be the number you passed in, *not* the number of
physical entries returned.

void
dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
enum dma_data_direction direction)
dma_sync_single(struct device *dev, dma_addr_t dma_handle, size_t size,
enum dma_data_direction direction)
void
dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle, size_t size,
enum dma_data_direction direction)
pci_dma_sync_single(struct pci_dev *hwdev, dma_addr_t dma_handle,
size_t size, int direction)
void
dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nelems,
enum dma_data_direction direction)
dma_sync_sg(struct device *dev, struct scatterlist *sg, int nelems,
enum dma_data_direction direction)
void
dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems,
enum dma_data_direction direction)
pci_dma_sync_sg(struct pci_dev *hwdev, struct scatterlist *sg,
int nelems, int direction)

Synchronise a single contiguous or scatter/gather mapping for the cpu
and device. With the sync_sg API, all the parameters must be the same
as those passed into the single mapping API. With the sync_single API,
you can use dma_handle and size parameters that aren't identical to
those passed into the single mapping API to do a partial sync.
Synchronise a single contiguous or scatter/gather mapping. All the
parameters must be the same as those passed into the single mapping
API.

Notes: You must do this:

Expand Down Expand Up @@ -421,9 +461,9 @@ void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
Part II - Advanced dma_ usage
-----------------------------

Warning: These pieces of the DMA API should not be used in the
majority of cases, since they cater for unlikely corner cases that
don't belong in usual drivers.
Warning: These pieces of the DMA API have no PCI equivalent. They
should also not be used in the majority of cases, since they cater for
unlikely corner cases that don't belong in usual drivers.

If you don't understand how cache line coherency works between a
processor and an I/O device, you should not be using this part of the
Expand Down Expand Up @@ -473,6 +513,16 @@ line, but it will guarantee that one or more cache lines fit exactly
into the width returned by this call. It will also always be a power
of two for easy alignment.

void
dma_sync_single_range(struct device *dev, dma_addr_t dma_handle,
unsigned long offset, size_t size,
enum dma_data_direction direction)

Does a partial sync, starting at offset and continuing for size. You
must be careful to observe the cache alignment and width when doing
anything like this. You must also be extra careful about accessing
memory you intend to sync partially.

void
dma_cache_sync(struct device *dev, void *vaddr, size_t size,
enum dma_data_direction direction)
Expand Down
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