Kernel-4.18.0-80.el8_samsung,exynos4210-mct

Samsung’s Multi Core Timer (MCT)

The Samsung’s Multi Core Timer (MCT) module includes two main blocks, the
global timer and CPU local timers. The global timer is a 64-bit free running
up-counter and can generate 4 interrupts when the counter reaches one of the
four preset counter values. The CPU local timers are 32-bit free running
down-counters and generate an interrupt when the counter expires. There is
one CPU local timer instantiated in MCT for every CPU in the system.

Required properties:

• compatible: should be “samsung,exynos4210-mct”.
  (a) “samsung,exynos4210-mct”, for mct compatible with Exynos4210 mct.
  (b) “samsung,exynos4412-mct”, for mct compatible with Exynos4412 mct.

• reg: base address of the mct controller and length of the address space
  it occupies.

• interrupts: the list of interrupts generated by the controller. The following
  should be the order of the interrupts specified. The local timer interrupts
  should be specified after the four global timer interrupts have been
  specified.

  0: Global Timer Interrupt 0
  1: Global Timer Interrupt 1
  2: Global Timer Interrupt 2
  3: Global Timer Interrupt 3
  4: Local Timer Interrupt 0
  5: Local Timer Interrupt 1
  6: ..
  7: ..
  i: Local Timer Interrupt n

  For MCT block that uses a per-processor interrupt for local timers, such
  as ones compatible with “samsung,exynos4412-mct”, only one local timer
  interrupt might be specified, meaning that all local timers use the same
  per processor interrupt.

Example 1: In this example, the IP contains two local timers, using separate
interrupts, so two local timer interrupts have been specified,
in addition to four global timer interrupts.

mct@10050000 {
    compatible = "samsung,exynos4210-mct";
    reg = <0x10050000 0x800>;
    interrupts = <0 57 0>, <0 69 0>, <0 70 0>, <0 71 0>,
             <0 42 0>, <0 48 0>;
};

Example 2: In this example, the timer interrupts are connected to two separate
interrupt controllers. Hence, an interrupt-map is created to map
the interrupts to the respective interrupt controllers.

mct@101c0000 {
    compatible = "samsung,exynos4210-mct";
    reg = <0x101C0000 0x800>;
    interrupt-parent = <&mct_map>;
    interrupts = <0>, <1>, <2>, <3>, <4>, <5>;

    mct_map: mct-map {
        #interrupt-cells = <1>;
        #address-cells = <0>;
        #size-cells = <0>;
        interrupt-map = <0 &gic 0 57 0>,
                <1 &gic 0 69 0>,
                <2 &combiner 12 6>,
                <3 &combiner 12 7>,
                <4 &gic 0 42 0>,
                <5 &gic 0 48 0>;
    };
};

Example 3: In this example, the IP contains four local timers, but using
a per-processor interrupt to handle them. Either all the local
timer interrupts can be specified, with the same interrupt specifier
value or just the first one.

mct@10050000 {
    compatible = "samsung,exynos4412-mct";
    reg = <0x10050000 0x800>;

    /* Both ways are possible in this case. Either: */
    interrupts = <0 57 0>, <0 69 0>, <0 70 0>, <0 71 0>,
             <0 42 0>;
    /* or: */
    interrupts = <0 57 0>, <0 69 0>, <0 70 0>, <0 71 0>,
             <0 42 0>, <0 42 0>, <0 42 0>, <0 42 0>;
};