FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/dma/brcm,bcm2835-dma.txt

     * BCM2835 DMA controller
     
     The BCM2835 DMA controller has 16 channels in total.
     Only the lower 13 channels have an associated IRQ.
     Some arbitrary channels are used by the firmware
     (1,3,6,7 in the current firmware version).
     The channels 0,2 and 3 have special functionality
     and should not be used by the driver.
     
    Required properties:
    - compatible: Should be "brcm,bcm2835-dma".
    - reg: Should contain DMA registers location and length.
    - interrupts: Should contain the DMA interrupts associated
                    to the DMA channels in ascending order.
    - interrupt-names: Should contain the names of the interrupt
                       in the form "dmaXX".
                       Use "dma-shared-all" for the common interrupt line
                       that is shared by all dma channels.
    - #dma-cells: Must be <1>, the cell in the dmas property of the
                    client device represents the DREQ number.
    - brcm,dma-channel-mask: Bit mask representing the channels
                             not used by the firmware in ascending order,
                             i.e. first channel corresponds to LSB.
    
    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>,
                         /* dma channel 11-14 share one irq */
                         <1 27>,
                         <1 27>,
                         <1 27>,
                         <1 27>,
                         /* unused shared irq for all channels */
                         <1 28>;
            interrupt-names = "dma0",
                              "dma1",
                              "dma2",
                              "dma3",
                              "dma4",
                              "dma5",
                              "dma6",
                              "dma7",
                              "dma8",
                              "dma9",
                              "dma10",
                              "dma11",
                              "dma12",
                              "dma13",
                              "dma14",
                              "dma-shared-all";
    
            #dma-cells = <1>;
            brcm,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.
    
    Example:
    
    bcm2835_i2s: i2s@7e203000 {
            compatible = "brcm,bcm2835-i2s";
            reg = < 0x7e203000 0x24>;
            clocks = <&clocks BCM2835_CLOCK_PCM>;
    
            dmas = <&dma 2>,
                   <&dma 3>;
            dma-names = "tx", "rx";
    };

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