arch_timer.txt 2.2 KB

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  1. * ARM architected timer
  2. ARM cores may have a per-core architected timer, which provides per-cpu timers,
  3. or a memory mapped architected timer, which provides up to 8 frames with a
  4. physical and optional virtual timer per frame.
  5. The per-core architected timer is attached to a GIC to deliver its
  6. per-processor interrupts via PPIs. The memory mapped timer is attached to a GIC
  7. to deliver its interrupts via SPIs.
  8. ** CP15 Timer node properties:
  9. - compatible : Should at least contain one of
  10. "arm,armv7-timer"
  11. "arm,armv8-timer"
  12. - interrupts : Interrupt list for secure, non-secure, virtual and
  13. hypervisor timers, in that order.
  14. - clock-frequency : The frequency of the main counter, in Hz. Optional.
  15. - always-on : a boolean property. If present, the timer is powered through an
  16. always-on power domain, therefore it never loses context.
  17. Example:
  18. timer {
  19. compatible = "arm,cortex-a15-timer",
  20. "arm,armv7-timer";
  21. interrupts = <1 13 0xf08>,
  22. <1 14 0xf08>,
  23. <1 11 0xf08>,
  24. <1 10 0xf08>;
  25. clock-frequency = <100000000>;
  26. };
  27. ** Memory mapped timer node properties:
  28. - compatible : Should at least contain "arm,armv7-timer-mem".
  29. - clock-frequency : The frequency of the main counter, in Hz. Optional.
  30. - reg : The control frame base address.
  31. Note that #address-cells, #size-cells, and ranges shall be present to ensure
  32. the CPU can address a frame's registers.
  33. A timer node has up to 8 frame sub-nodes, each with the following properties:
  34. - frame-number: 0 to 7.
  35. - interrupts : Interrupt list for physical and virtual timers in that order.
  36. The virtual timer interrupt is optional.
  37. - reg : The first and second view base addresses in that order. The second view
  38. base address is optional.
  39. - status : "disabled" indicates the frame is not available for use. Optional.
  40. Example:
  41. timer@f0000000 {
  42. compatible = "arm,armv7-timer-mem";
  43. #address-cells = <1>;
  44. #size-cells = <1>;
  45. ranges;
  46. reg = <0xf0000000 0x1000>;
  47. clock-frequency = <50000000>;
  48. frame@f0001000 {
  49. frame-number = <0>
  50. interrupts = <0 13 0x8>,
  51. <0 14 0x8>;
  52. reg = <0xf0001000 0x1000>,
  53. <0xf0002000 0x1000>;
  54. };
  55. frame@f0003000 {
  56. frame-number = <1>
  57. interrupts = <0 15 0x8>;
  58. reg = <0xf0003000 0x1000>;
  59. status = "disabled";
  60. };
  61. };