Commit 471de2c0 authored by Sudeep Holla's avatar Sudeep Holla Committed by Jassi Brar
Browse files

dt-bindings: mailbox: add doorbell support to ARM MHU 



The ARM MHU's reference manual states following:

"The MHU drives the signal using a 32-bit register, with all 32 bits
logically ORed together. The MHU provides a set of registers to enable
software to set, clear, and check the status of each of the bits of this
register independently.  The use of 32 bits for each interrupt line
enables software to provide more information about the source of the
interrupt. For example, each bit of the register can be associated with
a type of event that can contribute to raising the interrupt."

This patch thus extends the MHU controller's DT binding to add support
for doorbell mode.

Though the same MHU hardware controller is used in the two modes, A new
compatible string is added here to represent the combination of the MHU
hardware and the firmware sitting on the other side (which expects each
bit to represent a different signal now).

Reviewed-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Co-developed-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: default avatarJassi Brar <jaswinder.singh@linaro.org>
parent 9070f35d

Documentation/devicetree/bindings/mailbox/arm,mhu.yaml

+54 −6
Original line number Diff line number Diff line
@@ -18,21 +18,41 @@ description: | 
  remote clears it after having read the data.  The last channel is specified to

  be a 'Secure' resource, hence can't be used by Linux running NS.



  The MHU hardware also allows operations in doorbell mode. The MHU drives the

  interrupt signal using a 32-bit register, with all 32-bits logically ORed

  together. It provides a set of registers to enable software to set, clear and

  check the status of each of the bits of this register independently. The use

  of 32 bits per interrupt line enables software to provide more information

  about the source of the interrupt. For example, each bit of the register can

  be associated with a type of event that can contribute to raising the

  interrupt. Each of the 32-bits can be used as "doorbell" to alert the remote

  processor.



# We need a select here so we don't match all nodes with 'arm,primecell'

select:

  properties:

    compatible:

      contains:

        const: arm,mhu

        enum:

          - arm,mhu

          - arm,mhu-doorbell

  required:

    - compatible



properties:

  compatible:

    oneOf:

      - description: Data transfer mode

        items:

          - const: arm,mhu

          - const: arm,primecell



      - description: Doorbell mode

        items:

          - const: arm,mhu-doorbell

          - const: arm,primecell





  reg:

    maxItems: 1
@@ -51,8 +71,11 @@ properties: 
      - const: apb_pclk



  '#mbox-cells':

    description: Index of the channel.

    const: 1

    description: |

      Set to 1 in data transfer mode and represents index of the channel.

      Set to 2 in doorbell mode and represents index of the channel and doorbell

      number.

    enum: [ 1, 2 ]



required:

  - compatible
@@ -63,6 +86,7 @@ required: 
additionalProperties: false



examples:

  # Data transfer mode.

  - |

    soc {

        #address-cells = <2>;
@@ -85,3 +109,27 @@ examples: 
            mboxes = <&mhuA 1>; /* HP-NonSecure */

        };

    };



  # Doorbell mode.

  - |

    soc {

        #address-cells = <2>;

        #size-cells = <2>;



        mhuB: mailbox@2b2f0000 {

            #mbox-cells = <2>;

            compatible = "arm,mhu-doorbell", "arm,primecell";

            reg = <0 0x2b2f0000 0 0x1000>;

            interrupts = <0 36 4>, /* LP-NonSecure */

                         <0 35 4>, /* HP-NonSecure */

                         <0 37 4>; /* Secure */

            clocks = <&clock 0 2 1>;

            clock-names = "apb_pclk";

        };



        mhu_client_scpi: scpi@2f000000 {

            compatible = "arm,scpi";

            reg = <0 0x2f000000 0 0x200>;

            mboxes = <&mhuB 1 4>; /* HP-NonSecure, 5th doorbell */

        };

    };

CRA Git | Maintained and supported by SUSTech CRA and CCSE