1What:		/sys/firmware/acpi/interrupts/
2Date:		February 2008
3Contact:	Len Brown <lenb@kernel.org>
4Description:
5		All ACPI interrupts are handled via a single IRQ,
6		the System Control Interrupt (SCI), which appears
7		as "acpi" in /proc/interrupts.
8
9		However, one of the main functions of ACPI is to make
10		the platform understand random hardware without
11		special driver support.  So while the SCI handles a few
12		well known (fixed feature) interrupts sources, such
13		as the power button, it can also handle a variable
14		number of a "General Purpose Events" (GPE).
15
16		A GPE vectors to a specified handler in AML, which
17		can do a anything the BIOS writer wants from
18		OS context.  GPE 0x12, for example, would vector
19		to a level or edge handler called _L12 or _E12.
20		The handler may do its business and return.
21		Or the handler may send send a Notify event
22		to a Linux device driver registered on an ACPI device,
23		such as a battery, or a processor.
24
25		To figure out where all the SCI's are coming from,
26		/sys/firmware/acpi/interrupts contains a file listing
27		every possible source, and the count of how many
28		times it has triggered.
29
30		$ cd /sys/firmware/acpi/interrupts
31		$ grep . *
32		error:0
33		ff_gbl_lock:0
34		ff_pmtimer:0
35		ff_pwr_btn:0
36		ff_rt_clk:0
37		ff_slp_btn:0
38		gpe00:0
39		gpe01:0
40		gpe02:0
41		gpe03:0
42		gpe04:0
43		gpe05:0
44		gpe06:0
45		gpe07:0
46		gpe08:0
47		gpe09:174
48		gpe0A:0
49		gpe0B:0
50		gpe0C:0
51		gpe0D:0
52		gpe0E:0
53		gpe0F:0
54		gpe10:0
55		gpe11:60
56		gpe12:0
57		gpe13:0
58		gpe14:0
59		gpe15:0
60		gpe16:0
61		gpe17:0
62		gpe18:0
63		gpe19:7
64		gpe1A:0
65		gpe1B:0
66		gpe1C:0
67		gpe1D:0
68		gpe1E:0
69		gpe1F:0
70		gpe_all:241
71		sci:241
72
73		sci - The total number of times the ACPI SCI
74		has claimed an interrupt.
75
76		gpe_all - count of SCI caused by GPEs.
77
78		gpeXX - count for individual GPE source
79
80		ff_gbl_lock - Global Lock
81
82		ff_pmtimer - PM Timer
83
84		ff_pwr_btn - Power Button
85
86		ff_rt_clk - Real Time Clock
87
88		ff_slp_btn - Sleep Button
89
90		error - an interrupt that can't be accounted for above.
91
92		Root has permission to clear any of these counters.  Eg.
93		# echo 0 > gpe11
94
95		All counters can be cleared by clearing the total "sci":
96		# echo 0 > sci
97
98		None of these counters has an effect on the function
99		of the system, they are simply statistics.
100