About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / devicetree / bindings / arm / arch_timer.txt




Custom Search

Based on kernel version 3.15.4. Page generated on 2014-07-07 09:00 EST.

1	* ARM architected timer
2	
3	ARM cores may have a per-core architected timer, which provides per-cpu timers,
4	or a memory mapped architected timer, which provides up to 8 frames with a
5	physical and optional virtual timer per frame.
6	
7	The per-core architected timer is attached to a GIC to deliver its
8	per-processor interrupts via PPIs. The memory mapped timer is attached to a GIC
9	to deliver its interrupts via SPIs.
10	
11	** CP15 Timer node properties:
12	
13	- compatible : Should at least contain one of
14		"arm,armv7-timer"
15		"arm,armv8-timer"
16	
17	- interrupts : Interrupt list for secure, non-secure, virtual and
18	  hypervisor timers, in that order.
19	
20	- clock-frequency : The frequency of the main counter, in Hz. Optional.
21	
22	- always-on : a boolean property. If present, the timer is powered through an
23	  always-on power domain, therefore it never loses context.
24	
25	Example:
26	
27		timer {
28			compatible = "arm,cortex-a15-timer",
29				     "arm,armv7-timer";
30			interrupts = <1 13 0xf08>,
31				     <1 14 0xf08>,
32				     <1 11 0xf08>,
33				     <1 10 0xf08>;
34			clock-frequency = <100000000>;
35		};
36	
37	** Memory mapped timer node properties:
38	
39	- compatible : Should at least contain "arm,armv7-timer-mem".
40	
41	- clock-frequency : The frequency of the main counter, in Hz. Optional.
42	
43	- reg : The control frame base address.
44	
45	Note that #address-cells, #size-cells, and ranges shall be present to ensure
46	the CPU can address a frame's registers.
47	
48	A timer node has up to 8 frame sub-nodes, each with the following properties:
49	
50	- frame-number: 0 to 7.
51	
52	- interrupts : Interrupt list for physical and virtual timers in that order.
53	  The virtual timer interrupt is optional.
54	
55	- reg : The first and second view base addresses in that order. The second view
56	  base address is optional.
57	
58	- status : "disabled" indicates the frame is not available for use. Optional.
59	
60	Example:
61	
62		timer@f0000000 {
63			compatible = "arm,armv7-timer-mem";
64			#address-cells = <1>;
65			#size-cells = <1>;
66			ranges;
67			reg = <0xf0000000 0x1000>;
68			clock-frequency = <50000000>;
69	
70			frame@f0001000 {
71				frame-number = <0>
72				interrupts = <0 13 0x8>,
73					     <0 14 0x8>;
74				reg = <0xf0001000 0x1000>,
75				      <0xf0002000 0x1000>;
76			};
77	
78			frame@f0003000 {
79				frame-number = <1>
80				interrupts = <0 15 0x8>;
81				reg = <0xf0003000 0x1000>;
82				status = "disabled";
83			};
84		};
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.