Commit 1be5336b authored by Peter Ujfalusi's avatar Peter Ujfalusi Committed by Vinod Koul
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dmaengine: edma: New device tree binding 



With the old binding and driver architecture we had many issues:
No way to assign eDMA channels to event queues, thus not able to tune the
system by moving specific DMA channels to low/high priority servicing. We
moved the cyclic channels to high priority within the code, but that was
just a workaround to this issue.
Memcopy was fundamentally broken: even if the driver scanned the DT/devices
in the booted system for direct DMA users (which is not effective when the
events are going through a crossbar) and created a map of 'used' channels,
this information was not really usable. Since via dmaengien API the eDMA
driver will be called with _some_ channel number, we would try to request
this channel when any channel is requested for memcpy. By luck we got
channel which is not used by any device most of the time so things worked,
but if a device would have been using the given channel, but not requested
it, the memcpy channel would have been waiting for HW event.
The old code had the am33xx/am43xx DMA event router handling embedded. This
should have been done in a separate driver since it is not part of the
actual eDMA IP.
There were no way to 'lock' PaRAM slots to be used by the DSP for example
when booting with DT.
In DT boot the edma node used more than one hwmod which is not a good
practice and the kernel prints warning because of this.

With the new bindings and the changes in the driver we can:
- No regression with Legacy binding and non DT boot
- DMA channels can be assigned to any TC (to set priority)
- PaRAM slots can be reserved for other cores to use
- Dynamic power management for CC and TCs, if only TC0 is used all other TC
  can be powered down for example

Signed-off-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent f7c7cae9

Documentation/devicetree/bindings/dma/ti-edma.txt

+116 −1
Original line number Diff line number Diff line 
TI EDMA

Texas Instruments eDMA



The eDMA3 consists of two components: Channel controller (CC) and Transfer

Controller(s) (TC). The CC is the main entry for DMA users since it is

responsible for the DMA channel handling, while the TCs are responsible to

execute the actual DMA tansfer.



------------------------------------------------------------------------------

eDMA3 Channel Controller



Required properties:

- compatible:	"ti,edma3-tpcc" for the channel controller(s)

- #dma-cells:	Should be set to <2>. The first number is the DMA request

		number and the second is the TC the channel is serviced on.

- reg:		Memory map of eDMA CC

- reg-names:	"edma3_cc"

- interrupts:	Interrupt lines for CCINT, MPERR and CCERRINT.

- interrupt-names: "edma3_ccint", "emda3_mperr" and "edma3_ccerrint"

- ti,tptcs:	List of TPTCs associated with the eDMA in the following form:

		<&tptc_phandle TC_priority_number>. The highest priority is 0.



Optional properties:

- ti,hwmods:	Name of the hwmods associated to the eDMA CC

- ti,edma-memcpy-channels: List of channels allocated to be used for memcpy, iow

		these channels will be SW triggered channels. The list must

		contain 16 bits numbers, see example.

- ti,edma-reserved-slot-ranges: PaRAM slot ranges which should not be used by

		the driver, they are allocated to be used by for example the

		DSP. See example.



------------------------------------------------------------------------------

eDMA3 Transfer Controller



Required properties:

- compatible:	"ti,edma3-tptc" for the transfer controller(s)

- reg:		Memory map of eDMA TC

- interrupts:	Interrupt number for TCerrint.



Optional properties:

- ti,hwmods:	Name of the hwmods associated to the given eDMA TC

- interrupt-names: "edma3_tcerrint"



------------------------------------------------------------------------------

Example:



edma: edma@49000000 {

	compatible = "ti,edma3-tpcc";

	ti,hwmods = "tpcc";

	reg =	<0x49000000 0x10000>;

	reg-names = "edma3_cc";

	interrupts = <12 13 14>;

	interrupt-names = "edma3_ccint", "emda3_mperr", "edma3_ccerrint";

	dma-requests = <64>;

	#dma-cells = <2>;



	ti,tptcs = <&edma_tptc0 7>, <&edma_tptc1 7>, <&edma_tptc2 0>;



	/* Channel 20 and 21 is allocated for memcpy */

	ti,edma-memcpy-channels = /bits/ 16 <20 21>;

	/* The following PaRAM slots are reserved: 35-45 and 100-110 */

	ti,edma-reserved-slot-ranges = /bits/ 16 <35 10>,

				       /bits/ 16 <100 10>;

};



edma_tptc0: tptc@49800000 {

	compatible = "ti,edma3-tptc";

	ti,hwmods = "tptc0";

	reg =	<0x49800000 0x100000>;

	interrupts = <112>;

	interrupt-names = "edm3_tcerrint";

};



edma_tptc1: tptc@49900000 {

	compatible = "ti,edma3-tptc";

	ti,hwmods = "tptc1";

	reg =	<0x49900000 0x100000>;

	interrupts = <113>;

	interrupt-names = "edm3_tcerrint";

};



edma_tptc2: tptc@49a00000 {

	compatible = "ti,edma3-tptc";

	ti,hwmods = "tptc2";

	reg =	<0x49a00000 0x100000>;

	interrupts = <114>;

	interrupt-names = "edm3_tcerrint";

};



sham: sham@53100000 {

	compatible = "ti,omap4-sham";

	ti,hwmods = "sham";

	reg = <0x53100000 0x200>;

	interrupts = <109>;

	/* DMA channel 36 executed on eDMA TC0 - low priority queue */

	dmas = <&edma 36 0>;

	dma-names = "rx";

};



mcasp0: mcasp@48038000 {

	compatible = "ti,am33xx-mcasp-audio";

	ti,hwmods = "mcasp0";

	reg = <0x48038000 0x2000>,

		<0x46000000 0x400000>;

	reg-names = "mpu", "dat";

	interrupts = <80>, <81>;

	interrupt-names = "tx", "rx";

	status = "disabled";

	/* DMA channels 8 and 9 executed on eDMA TC2 - high priority queue */

	dmas = <&edma 8 2>,

	       <&edma 9 2>;

	dma-names = "tx", "rx";

};



------------------------------------------------------------------------------

DEPRECATED binding, new DTS files must use the ti,edma3-tpcc/ti,edma3-tptc

binding.



Required properties:

- compatible : "ti,edma3"

drivers/dma/edma.c

+340 −146

File changed.

Preview size limit exceeded, changes collapsed.

include/linux/platform_data/edma.h

+3 −0
Original line number Diff line number Diff line
@@ -71,6 +71,9 @@ struct edma_soc_info { 
	/* Resource reservation for other cores */

	struct edma_rsv_info	*rsv;



	/* List of channels allocated for memcpy, terminated with -1 */

	s16			*memcpy_channels;



	s8	(*queue_priority_mapping)[2];

	const s16	(*xbar_chans)[2];

};

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