On Nov 11, 2013, at 4:05 PM, Florian Meier <florian.meier@xxxxxxxx> wrote:
> Add support for DMA controller of BCM2835 as used in the Raspberry Pi.
> Currently it only supports cyclic DMA.
>
> Signed-off-by: Florian Meier <florian.meier@xxxxxxxx>
> ---
>
> Thank you for your comments!
> I hope I have now removed all leftovers of the sg struct.
> Regarding the endian-ness: I have not found any hint about that in the datasheet. Therefore, I chose uint32_t. If you think fixed le32 is more likely I will change it.
> The PAD fields do not seem to be used, but the datasheet states they should be set to 0.
>
>
> .../devicetree/bindings/dma/bcm2835-dma.txt | 57 ++
> arch/arm/boot/dts/bcm2835.dtsi | 23 +
> drivers/dma/Kconfig | 6 +
> drivers/dma/Makefile | 1 +
> drivers/dma/bcm2835-dma.c | 810 ++++++++++++++++++++
> 5 files changed, 897 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/dma/bcm2835-dma.txt
> create mode 100644 drivers/dma/bcm2835-dma.c
>
> diff --git a/Documentation/devicetree/bindings/dma/bcm2835-dma.txt b/Documentation/devicetree/bindings/dma/bcm2835-dma.txt
> new file mode 100644
> index 0000000..9542ac8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/bcm2835-dma.txt
> @@ -0,0 +1,57 @@
> +* BCM2835 DMA controller
> +
> +Required properties:
> +- compatible: Should be "brcm,bcm2835-dma".
> +- reg: Should contain DMA registers location and length.
> +- interrupts: Should contain all DMA interrupts. First cell is the IRQ bank
> + Second cell is the IRQ number.
Can you be more specific about what you mean by ‘all DMA interrupts’?
> +- #dma-cells: Must be <1>, used to represent the number of integer cells in
> +the dmas property of client devices.
> +- dma-channels: Maximum number of DMA channels available
> +- dma-requests: Number of DMA Requests.
> +- dma-channel-mask: Bit mask representing the channels available.
Should be brcm,dma-channel-mask
> +
> +Example:
> +
> +dma: dma@7e007000 {
> + compatible = "brcm,bcm2835-dma";
> + reg = <0x7e007000 0xf00>;
> + interrupts = <1 16
> + 1 17
> + 1 18
> + 1 19
> + 1 20
> + 1 21
> + 1 22
> + 1 23
> + 1 24
> + 1 25
> + 1 26
> + 1 27
> + 1 28>;
> +
> + #dma-cells = <1>;
> + dma-channels = <15>;
> + dma-requests = <32>;
> + dma-channel-mask = <0x7f35>;
> +};
> +
> +DMA clients connected to the BCM2835 DMA controller must use the format
> +described in the dma.txt file, using a two-cell specifier for each channel:
> +a phandle plus one integer cells.
> +The two cells in order are:
> +
> +1. A phandle pointing to the DMA controller.
> +2. The DREQ number.
> +
> +Example:
> +
> +bcm2835_i2s: i2s@7e203000 {
> + compatible = "brcm,bcm2835-i2s";
> + reg = < 0x7e203000 0x20
> + 0x7e101098 0x02>;
> +
> + dmas = <&dma 2
> + &dma 3>;
> + dma-names = "tx", "rx";
> +};
- k
--
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