android_kernel_xiaomi_sm8350/Documentation/powerpc/dts-bindings/fsl/dma.txt
Ira Snyder d3f620b2c4 fsldma: simplify IRQ probing and handling
The IRQ probing is needlessly complex. All off the 83xx device trees in
arch/powerpc/boot/dts/ specify 5 interrupts per DMA controller: one for the
controller, and one for each channel. These interrupts are all attached to
the same IRQ line.

This causes an interesting situation if two channels interrupt at the same
time. The per-controller handler will handle the first channel, and the
per-channel handler will handle the remaining channels.

Instead of this mess, we fix the bug in the per-controller handler, and
make it handle all channels that generated an interrupt. When a
per-controller handler is specified in the device tree, we prefer to use
the shared handler instead of the per-channel handler.

The 85xx/86xx controllers do not have a per-controller interrupt, and
instead use a per-channel interrupt. This behavior has not been changed.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2010-02-02 14:51:41 -07:00

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* Freescale 83xx DMA Controller
Freescale PowerPC 83xx have on chip general purpose DMA controllers.
Required properties:
- compatible : compatible list, contains 2 entries, first is
"fsl,CHIP-dma", where CHIP is the processor
(mpc8349, mpc8360, etc.) and the second is
"fsl,elo-dma"
- reg : <registers mapping for DMA general status reg>
- ranges : Should be defined as specified in 1) to describe the
DMA controller channels.
- cell-index : controller index. 0 for controller @ 0x8100
- interrupts : <interrupt mapping for DMA IRQ>
- interrupt-parent : optional, if needed for interrupt mapping
- DMA channel nodes:
- compatible : compatible list, contains 2 entries, first is
"fsl,CHIP-dma-channel", where CHIP is the processor
(mpc8349, mpc8350, etc.) and the second is
"fsl,elo-dma-channel". However, see note below.
- reg : <registers mapping for channel>
- cell-index : dma channel index starts at 0.
Optional properties:
- interrupts : <interrupt mapping for DMA channel IRQ>
(on 83xx this is expected to be identical to
the interrupts property of the parent node)
- interrupt-parent : optional, if needed for interrupt mapping
Example:
dma@82a8 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "fsl,mpc8349-dma", "fsl,elo-dma";
reg = <0x82a8 4>;
ranges = <0 0x8100 0x1a4>;
interrupt-parent = <&ipic>;
interrupts = <71 8>;
cell-index = <0>;
dma-channel@0 {
compatible = "fsl,mpc8349-dma-channel", "fsl,elo-dma-channel";
cell-index = <0>;
reg = <0 0x80>;
interrupt-parent = <&ipic>;
interrupts = <71 8>;
};
dma-channel@80 {
compatible = "fsl,mpc8349-dma-channel", "fsl,elo-dma-channel";
cell-index = <1>;
reg = <0x80 0x80>;
interrupt-parent = <&ipic>;
interrupts = <71 8>;
};
dma-channel@100 {
compatible = "fsl,mpc8349-dma-channel", "fsl,elo-dma-channel";
cell-index = <2>;
reg = <0x100 0x80>;
interrupt-parent = <&ipic>;
interrupts = <71 8>;
};
dma-channel@180 {
compatible = "fsl,mpc8349-dma-channel", "fsl,elo-dma-channel";
cell-index = <3>;
reg = <0x180 0x80>;
interrupt-parent = <&ipic>;
interrupts = <71 8>;
};
};
* Freescale 85xx/86xx DMA Controller
Freescale PowerPC 85xx/86xx have on chip general purpose DMA controllers.
Required properties:
- compatible : compatible list, contains 2 entries, first is
"fsl,CHIP-dma", where CHIP is the processor
(mpc8540, mpc8540, etc.) and the second is
"fsl,eloplus-dma"
- reg : <registers mapping for DMA general status reg>
- cell-index : controller index. 0 for controller @ 0x21000,
1 for controller @ 0xc000
- ranges : Should be defined as specified in 1) to describe the
DMA controller channels.
- DMA channel nodes:
- compatible : compatible list, contains 2 entries, first is
"fsl,CHIP-dma-channel", where CHIP is the processor
(mpc8540, mpc8560, etc.) and the second is
"fsl,eloplus-dma-channel". However, see note below.
- cell-index : dma channel index starts at 0.
- reg : <registers mapping for channel>
- interrupts : <interrupt mapping for DMA channel IRQ>
- interrupt-parent : optional, if needed for interrupt mapping
Example:
dma@21300 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "fsl,mpc8540-dma", "fsl,eloplus-dma";
reg = <0x21300 4>;
ranges = <0 0x21100 0x200>;
cell-index = <0>;
dma-channel@0 {
compatible = "fsl,mpc8540-dma-channel", "fsl,eloplus-dma-channel";
reg = <0 0x80>;
cell-index = <0>;
interrupt-parent = <&mpic>;
interrupts = <20 2>;
};
dma-channel@80 {
compatible = "fsl,mpc8540-dma-channel", "fsl,eloplus-dma-channel";
reg = <0x80 0x80>;
cell-index = <1>;
interrupt-parent = <&mpic>;
interrupts = <21 2>;
};
dma-channel@100 {
compatible = "fsl,mpc8540-dma-channel", "fsl,eloplus-dma-channel";
reg = <0x100 0x80>;
cell-index = <2>;
interrupt-parent = <&mpic>;
interrupts = <22 2>;
};
dma-channel@180 {
compatible = "fsl,mpc8540-dma-channel", "fsl,eloplus-dma-channel";
reg = <0x180 0x80>;
cell-index = <3>;
interrupt-parent = <&mpic>;
interrupts = <23 2>;
};
};
Note on DMA channel compatible properties: The compatible property must say
"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel" to be used by the Elo DMA
driver (fsldma). Any DMA channel used by fsldma cannot be used by another
DMA driver, such as the SSI sound drivers for the MPC8610. Therefore, any DMA
channel that should be used for another driver should not use
"fsl,elo-dma-channel" or "fsl,eloplus-dma-channel". For the SSI drivers, for
example, the compatible property should be "fsl,ssi-dma-channel". See ssi.txt
for more information.