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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
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+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>;
+ };