Documentation/devicetree/bindings/dma/brcm,bcm2835-dma.txt

   1 * BCM2835 DMA controller
   2
   3 The BCM2835 DMA controller has 16 channels in total.
   4 Only the lower 13 channels have an associated IRQ.
   5 Some arbitrary channels are used by the firmware
   6 (1,3,6,7 in the current firmware version).
   7 The channels 0,2 and 3 have special functionality
   8 and should not be used by the driver.
   9
  10 Required properties:
  11 - compatible: Should be "brcm,bcm2835-dma".
  12 - reg: Should contain DMA registers location and length.
  13 - interrupts: Should contain the DMA interrupts associated
  14                 to the DMA channels in ascending order.
  15 - interrupt-names: Should contain the names of the interrupt
  16                    in the form "dmaXX".
  17                    Use "dma-shared-all" for the common interrupt line
  18                    that is shared by all dma channels.
  19 - #dma-cells: Must be <1>, the cell in the dmas property of the
  20                 client device represents the DREQ number.
  21 - brcm,dma-channel-mask: Bit mask representing the channels
  22                          not used by the firmware in ascending order,
  23                          i.e. first channel corresponds to LSB.
  24
  25 Example:
  26
  27 dma: dma@7e007000 {
  28         compatible = "brcm,bcm2835-dma";
  29         reg = <0x7e007000 0xf00>;
  30         interrupts = <1 16>,
  31                      <1 17>,
  32                      <1 18>,
  33                      <1 19>,
  34                      <1 20>,
  35                      <1 21>,
  36                      <1 22>,
  37                      <1 23>,
  38                      <1 24>,
  39                      <1 25>,
  40                      <1 26>,
  41                      /* dma channel 11-14 share one irq */
  42                      <1 27>,
  43                      <1 27>,
  44                      <1 27>,
  45                      <1 27>,
  46                      /* unused shared irq for all channels */
  47                      <1 28>;
  48         interrupt-names = "dma0",
  49                           "dma1",
  50                           "dma2",
  51                           "dma3",
  52                           "dma4",
  53                           "dma5",
  54                           "dma6",
  55                           "dma7",
  56                           "dma8",
  57                           "dma9",
  58                           "dma10",
  59                           "dma11",
  60                           "dma12",
  61                           "dma13",
  62                           "dma14",
  63                           "dma-shared-all";
  64
  65         #dma-cells = <1>;
  66         brcm,dma-channel-mask = <0x7f35>;
  67 };
  68
  69
  70 DMA clients connected to the BCM2835 DMA controller must use the format
  71 described in the dma.txt file, using a two-cell specifier for each channel.
  72
  73 Example:
  74
  75 bcm2835_i2s: i2s@7e203000 {
  76         compatible = "brcm,bcm2835-i2s";
  77         reg = < 0x7e203000 0x20>,
  78               < 0x7e101098 0x02>;
  79
  80         dmas = <&dma 2>,
  81                <&dma 3>;
  82         dma-names = "tx", "rx";
  83 };