Kernel-4.18.0-80.el8_smp-sra

Allwinner SRAM for smp bringup:

Allwinner’s A80 SoC uses part of the secure sram for hotplugging of the
primary core (cpu0). Once the core gets powered up it checks if a magic
value is set at a specific location. If it is then the BROM will jump
to the software entry address, instead of executing a standard boot.

Therefore a reserved section sub-node has to be added to the mmio-sram
declaration.

Note that this is separate from the Allwinner SRAM controller found in
../../sram/sunxi-sram.txt. This SRAM is secure only and not mappable to
any device.

Also there are no “secure-only” properties. The implementation should
check if this SRAM is usable first.

Required sub-node properties:

• compatible : depending on the SoC this should be one of:

    "allwinner,sun9i-a80-smp-sram"
  

The rest of the properties should follow the generic mmio-sram discription
found in ../../misc/sram.txt

Example:

sram_b: sram@20000 {
    /* 256 KiB secure SRAM at 0x20000 */
    compatible = "mmio-sram";
    reg = <0x00020000 0x40000>;
    #address-cells = <1>;
    #size-cells = <1>;
    ranges = <0 0x00020000 0x40000>;

    smp-sram@1000 {
        /*
         * This is checked by BROM to determine if
         * cpu0 should jump to SMP entry vector
         */
        compatible = "allwinner,sun9i-a80-smp-sram";
        reg = <0x1000 0x8>;
    };
};