Documentation/devicetree/bindings/soc/qcom/qcom,smp2p.txt

   1 Qualcomm Shared Memory Point 2 Point binding
   2
   3 The Shared Memory Point to Point (SMP2P) protocol facilitates communication of
   4 a single 32-bit value between two processors.  Each value has a single writer
   5 (the local side) and a single reader (the remote side).  Values are uniquely
   6 identified in the system by the directed edge (local processor ID to remote
   7 processor ID) and a string identifier.
   8
   9 - compatible:
  10         Usage: required
  11         Value type: <string>
  12         Definition: must be one of:
  13                     "qcom,smp2p"
  14
  15 - interrupts:
  16         Usage: required
  17         Value type: <prop-encoded-array>
  18         Definition: one entry specifying the smp2p notification interrupt
  19
  20 - qcom,ipc:
  21         Usage: required
  22         Value type: <prop-encoded-array>
  23         Definition: three entries specifying the outgoing ipc bit used for
  24                     signaling the remote end of the smp2p edge:
  25                     - phandle to a syscon node representing the apcs registers
  26                     - u32 representing offset to the register within the syscon
  27                     - u32 representing the ipc bit within the register
  28
  29 - qcom,smem:
  30         Usage: required
  31         Value type: <u32 array>
  32         Definition: two identifiers of the inbound and outbound smem items used
  33                     for this edge
  34
  35 - qcom,local-pid:
  36         Usage: required
  37         Value type: <u32>
  38         Definition: specifies the identfier of the local endpoint of this edge
  39
  40 - qcom,remote-pid:
  41         Usage: required
  42         Value type: <u32>
  43         Definition: specifies the identfier of the remote endpoint of this edge
  44
  45 = SUBNODES
  46 Each SMP2P pair contain a set of inbound and outbound entries, these are
  47 described in subnodes of the smp2p device node. The node names are not
  48 important.
  49
  50 - qcom,entry-name:
  51         Usage: required
  52         Value type: <string>
  53         Definition: specifies the name of this entry, for inbound entries this
  54                     will be used to match against the remotely allocated entry
  55                     and for outbound entries this name is used for allocating
  56                     entries
  57
  58 - interrupt-controller:
  59         Usage: required for incoming entries
  60         Value type: <empty>
  61         Definition: marks the entry as inbound; the node should be specified
  62                     as a two cell interrupt-controller as defined in
  63                     "../interrupt-controller/interrupts.txt"
  64                     If not specified this node will denote the outgoing entry
  65
  66 - #interrupt-cells:
  67         Usage: required for incoming entries
  68         Value type: <u32>
  69         Definition: must be 2 - denoting the bit in the entry and IRQ flags
  70
  71 - #qcom,smem-state-cells:
  72         Usage: required for outgoing entries
  73         Value type: <u32>
  74         Definition: must be 1 - denoting the bit in the entry
  75
  76 = EXAMPLE
  77 The following example shows the SMP2P setup with the wireless processor,
  78 defined from the 8974 apps processor's point-of-view. It encompasses one
  79 inbound and one outbound entry:
  80
  81 wcnss-smp2p {
  82         compatible = "qcom,smp2p";
  83         qcom,smem = <431>, <451>;
  84
  85         interrupts = <0 143 1>;
  86
  87         qcom,ipc = <&apcs 8 18>;
  88
  89         qcom,local-pid = <0>;
  90         qcom,remote-pid = <4>;
  91
  92         wcnss_smp2p_out: master-kernel {
  93                 qcom,entry-name = "master-kernel";
  94
  95                 #qcom,smem-state-cells = <1>;
  96         };
  97
  98         wcnss_smp2p_in: slave-kernel {
  99                 qcom,entry-name = "slave-kernel";
 100
 101                 interrupt-controller;
 102                 #interrupt-cells = <2>;
 103         };
 104 };