diff options
Diffstat (limited to 'Documentation/dmaengine')
| -rw-r--r-- | Documentation/dmaengine/provider.txt | 97 |
1 files changed, 55 insertions, 42 deletions
diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt index 766658ccf235..05d2280190f1 100644 --- a/Documentation/dmaengine/provider.txt +++ b/Documentation/dmaengine/provider.txt @@ -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 +299,36 @@ 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_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_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 + - This call is mandatory for slave operations only. This should NOT be + set or expected to be set for memcpy operations. + If a driver support both, it should use this call for slave + operations only and not for memcpy ones. + + * 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) |