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Documentation: dmaengine: Update the documentation

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Now that we have splitted device_control and removed device_slave_caps in favor
of a few dma_device variables, update the documentation accordingly.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Maxime Ripard 2014-11-17 14:42:55 +01:00 committed by Vinod Koul
parent 2c44ad914c
commit 1faab1f2e3
1 changed files with 50 additions and 41 deletions
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91
Documentation/dmaengine/provider.txt
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@ -113,6 +113,31 @@ need to initialize a few fields in there:
* channels: should be initialized as a list using the
INIT_LIST_HEAD macro for example
* src_addr_widths:
- should contain a bitmask of the supported source transfer width
* dst_addr_widths:
- should contain a bitmask of the supported destination transfer
width
* directions:
- should contain a bitmask of the supported slave directions
(i.e. excluding mem2mem transfers)
* residue_granularity:
- Granularity of the transfer residue reported to dma_set_residue.
- This can be either:
+ Descriptor
-> Your device doesn't support any kind of residue
reporting. The framework will only know that a particular
transaction descriptor is done.
+ Segment
-> Your device is able to report which chunks have been
transferred
+ Burst
-> Your device is able to report which burst have been
transferred
* dev: should hold the pointer to the struct device associated
to your current driver instance.
@ -274,48 +299,32 @@ supported.
account the current period.
- This function can be called in an interrupt context.
* device_control
- Used by client drivers to control and configure the channel it
has a handle on.
- Called with a command and an argument
+ The command is one of the values listed by the enum
dma_ctrl_cmd. The valid commands are:
+ DMA_PAUSE
+ Pauses a transfer on the channel
+ This command should operate synchronously on the channel,
pausing right away the work of the given channel
+ DMA_RESUME
+ Restarts a transfer on the channel
+ This command should operate synchronously on the channel,
resuming right away the work of the given channel
+ DMA_TERMINATE_ALL
+ Aborts all the pending and ongoing transfers on the
channel
+ This command should operate synchronously on the channel,
terminating right away all the channels
+ DMA_SLAVE_CONFIG
+ Reconfigures the channel with passed configuration
+ This command should NOT perform synchronously, or on any
currently queued transfers, but only on subsequent ones
+ In this case, the function will receive a
dma_slave_config structure pointer as an argument, that
will detail which configuration to use.
+ Even though that structure contains a direction field,
this field is deprecated in favor of the direction
argument given to the prep_* functions
+ FSLDMA_EXTERNAL_START
+ TODO: Why does that even exist?
+ The argument is an opaque unsigned long. This actually is a
pointer to a struct dma_slave_config that should be used only
in the DMA_SLAVE_CONFIG.
* device_config
- Reconfigures the channel with the configuration given as
argument
- This command should NOT perform synchronously, or on any
currently queued transfers, but only on subsequent ones
- In this case, the function will receive a dma_slave_config
structure pointer as an argument, that will detail which
configuration to use.
- Even though that structure contains a direction field, this
field is deprecated in favor of the direction argument given to
the prep_* functions
* device_slave_caps
- Called through the framework by client drivers in order to have
an idea of what are the properties of the channel allocated to
them.
- Such properties are the buswidth, available directions, etc.
- Required for every generic layer doing DMA transfers, such as
ASoC.
* device_pause
- Pauses a transfer on the channel
- This command should operate synchronously on the channel,
pausing right away the work of the given channel
* device_resume
- Resumes a transfer on the channel
- This command should operate synchronously on the channel,
pausing right away the work of the given channel
* device_terminate_all
- Aborts all the pending and ongoing transfers on the channel
- This command should operate synchronously on the channel,
terminating right away all the channels
Misc notes (stuff that should be documented, but don't really know
where to put them)