linux.git/include/linux/of_dma.h, branch v7.1-rc4

dmaengine: of_dma: Add devm_of_dma_controller_register()

2026-03-09T11:20:47+00:00

Add a managed API, devm_of_dma_controller_register(), to simplify DMA
engine controller registration by automatically handling resource
cleanup.

Signed-off-by: Frank Li 
Link: https://patch.msgid.link/20260225-mxsdma-module-v3-1-8f798b13baa6@nxp.com
Signed-off-by: Vinod Koul

of: Use SPDX license tag for DT files

2018-01-08T14:22:45+00:00

Convert remaining DT files to use SPDX-License-Identifier tags.

Cc: Benjamin Herrenschmidt 
Cc: Guennadi Liakhovetski 
Cc: Paul Mackerras 
Cc: Pantelis Antoniou 
Reviewed-by: Frank Rowand 
Reviewed-by: Philippe Ombredanne 
Signed-off-by: Rob Herring

dmaengine: of_dma: Correct return code for of_dma_request_slave_channel in case !CONFIG_OF

2015-11-16T03:33:21+00:00

of_dma_request_slave_channel should return either pointer for valid
dma_chan or ERR_PTR() error code, NULL is not expected to be returned.

Signed-off-by: Peter Ujfalusi 
Acked-by: Arnd Bergmann 
Signed-off-by: Vinod Koul

dmaengine: OF DMAEngine API based on CONFIG_DMA_OF instead of CONFIG_OF

2015-10-01T02:09:55+00:00

5fa422c ("dmaengine: move drivers/of/dma.c -> drivers/dma/of-dma.c")
moved OF base DMAEngine code to of-dma.c, then it based on CONFIG_DMA_OF.
But, OF base DMAEngine API on of_dma.h still based on CONFIG_OF now.
So, current kernel can't find OF base DMAEngine API if .config has CONFIG_OF,
but not have CONFIG_DMA_OF. This patch tidyup it.

Signed-off-by: Kuninori Morimoto 
Signed-off-by: Vinod Koul

dmaengine: of_dma: Support for DMA routers

2015-05-09T11:41:25+00:00

DMA routers are transparent devices used to mux DMA requests from
peripherals to DMA controllers. They are used when the SoC integrates more
devices with DMA requests then their controller can handle.
DRA7x is one example of such SoC, where the sDMA can hanlde 128 DMA request
lines, but in SoC level it has 205 DMA requests.

The of_dma_router will be registered as of_dma_controller with special
xlate function and additional parameters. The driver for the router is
responsible to craft the dma_spec (in the of_dma_route_allocate callback)
which can be used to requests a DMA channel from the real DMA controller.
This way the router can be transparent for the system while remaining generic
enough to be used in different environments.

Signed-off-by: Peter Ujfalusi 
Signed-off-by: Vinod Koul

dmaengine: of: add common xlate function for matching by channel id

2014-07-25T18:51:41+00:00

This patch adds a new common OF dma xlate callback function which will match a
channel by it's id. The binding expects one integer argument which it will use to
lookup the channel by the id.

Unlike of_dma_simple_xlate this function is able to handle a system with
multiple DMA controllers. When registering the of dma provider with
of_dma_controller_register a pointer to the dma_device struct which is
associated with the dt node needs to passed as the data parameter.
New function will use this pointer to match only channels which belong to the
specified DMA controller.

Signed-off-by: Alexander Popov 
Signed-off-by: Vinod Koul

dma: of: Remove check on always true condition

2013-06-12T02:19:19+00:00

Both of_dma_nbcells field of the of_dma_controller and the args_count field of
the dma_spec are initialized by parsing the #dma-cells attribute of their device
tree node. So if the device tree nodes of a DMA controller and the dma_spec
match this means that of_dma_nbcells and args_count will also match. So the
second test in the of_dma_find_controller loop is redundant because given the
first test yields true the second test will also yield true. So we can safely
remove the test whether of_dma_nbcells matches args_count. Since this was the
last user of the of_dma_nbcells field we can remove it altogether.

Signed-off-by: Lars-Peter Clausen 
Acked-by: Arnd Bergmann 
Signed-off-by: Vinod Koul

dma:of: Use a mutex to protect the of_dma_list

2013-05-02T16:20:38+00:00

Currently the OF DMA code uses a spin lock to protect the of_dma_list from
concurrent access and a per controller reference count to protect the controller
from being freed while a request operation is in progress. If
of_dma_controller_free() is called for a controller who's reference count is not
zero it will return -EBUSY and not remove the controller. This is fine up until
here, but leaves the question what the caller of of_dma_controller_free() is
supposed to do if the controller couldn't be freed.  The only viable solution
for the caller is to spin on of_dma_controller_free() until it returns success.
E.g.

	do {
		ret = of_dma_controller_free(dev->of_node)
	} while (ret != -EBUSY);

This is rather ugly and unnecessary and none of the current users of
of_dma_controller_free() check it's return value anyway. Instead protect the
list by a mutex. The mutex will be held as long as a request operation is in
progress. So if of_dma_controller_free() is called while a request operation is
in progress it will be put to sleep and only wake up once the request operation
has finished.

This means that it is no longer possible to register or unregister OF DMA
controllers from a context where it's not possible to sleep. But I doubt that
we'll ever need this.

Also rename of_dma_get_controller back to of_dma_find_controller.

Signed-off-by: Lars-Peter Clausen 
Acked-by: Arnd Bergmann 
Signed-off-by: Vinod Koul

DMA: of: Constant names

2013-04-15T04:22:03+00:00

No DMA of-function alters the name, so this patch changes the name arguments
to be constant. Most drivers will probably request DMA channels using a
constant name.

Signed-off-by: Markus Pargmann 
Signed-off-by: Vinod Koul

dmaengine: fix !of_dma compilation warning

2013-01-08T06:05:02+00:00

Reported-by: Stephen Rothwell 
Reported-by: Fengguang Wu 
Signed-off-by: Vinod Koul