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    SubjectRE: [PATCH v5 1/2] dt-bindings: mailbox: add binding doc for the ARM SMC/HVC mailbox
    Date
    > Subject: Re: [PATCH v5 1/2] dt-bindings: mailbox: add binding doc for the ARM
    > SMC/HVC mailbox
    >
    > On Fri, Aug 30, 2019 at 2:37 AM Peng Fan <peng.fan@nxp.com> wrote:
    > >
    > > Hi Jassi,
    > >
    > > > Subject: Re: [PATCH v5 1/2] dt-bindings: mailbox: add binding doc
    > > > for the ARM SMC/HVC mailbox
    > > >
    > > > On Fri, Aug 30, 2019 at 1:28 AM Peng Fan <peng.fan@nxp.com> wrote:
    > > >
    > > > > > > +examples:
    > > > > > > + - |
    > > > > > > + sram@910000 {
    > > > > > > + compatible = "mmio-sram";
    > > > > > > + reg = <0x0 0x93f000 0x0 0x1000>;
    > > > > > > + #address-cells = <1>;
    > > > > > > + #size-cells = <1>;
    > > > > > > + ranges = <0 0x0 0x93f000 0x1000>;
    > > > > > > +
    > > > > > > + cpu_scp_lpri: scp-shmem@0 {
    > > > > > > + compatible = "arm,scmi-shmem";
    > > > > > > + reg = <0x0 0x200>;
    > > > > > > + };
    > > > > > > +
    > > > > > > + cpu_scp_hpri: scp-shmem@200 {
    > > > > > > + compatible = "arm,scmi-shmem";
    > > > > > > + reg = <0x200 0x200>;
    > > > > > > + };
    > > > > > > + };
    > > > > > > +
    > > > > > > + firmware {
    > > > > > > + smc_mbox: mailbox {
    > > > > > > + #mbox-cells = <1>;
    > > > > > > + compatible = "arm,smc-mbox";
    > > > > > > + method = "smc";
    > > > > > > + arm,num-chans = <0x2>;
    > > > > > > + transports = "mem";
    > > > > > > + /* Optional */
    > > > > > > + arm,func-ids = <0xc20000fe>, <0xc20000ff>;
    > > > > > >
    > > > > > SMC/HVC is synchronously(block) running in "secure mode", i.e,
    > > > > > there can only be one instance running platform wide. Right?
    > > > >
    > > > > I think there could be channel for TEE, and channel for Linux.
    > > > > For virtualization case, there could be dedicated channel for each VM.
    > > > >
    > > > I am talking from Linux pov. Functions 0xfe and 0xff above, can't
    > > > both be active at the same time, right?
    > >
    > > If I get your point correctly,
    > > On UP, both could not be active. On SMP, tx/rx could be both active,
    > > anyway this depends on secure firmware and Linux firmware design.
    > >
    > > Do you have any suggestions about arm,func-ids here?
    > >
    > I was thinking if this is just an instruction, why can't each channel be
    > represented as a controller, i.e, have exactly one func-id per controller node.
    > Define as many controllers as you need channels ?

    I am ok, this could make driver code simpler. Something as below?

    smc_tx_mbox: tx_mbox {
    #mbox-cells = <0>;
    compatible = "arm,smc-mbox";
    method = "smc";
    transports = "mem";
    arm,func-id = <0xc20000fe>;
    };

    smc_rx_mbox: rx_mbox {
    #mbox-cells = <0>;
    compatible = "arm,smc-mbox";
    method = "smc";
    transports = "mem";
    arm,func-id = <0xc20000ff>;
    };

    firmware {
    scmi {
    compatible = "arm,scmi";
    mboxes = <&smc_tx_mbox>, <&smc_rx_mbox 1>;
    mbox-names = "tx", "rx";
    shmem = <&cpu_scp_lpri>, <&cpu_scp_hpri>;
    };
    };

    Thanks,
    Peng.

    >
    > -j
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