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+What:           /sys/firmware/acpi/interrupts/
+Date:           February 2008
+Contact:        Len Brown <lenb@kernel.org>
+Description:
+                All ACPI interrupts are handled via a single IRQ,
+                the System Control Interrupt (SCI), which appears
+                as "acpi" in /proc/interrupts.
+
+                However, one of the main functions of ACPI is to make
+                the platform understand random hardware without
+                special driver support.  So while the SCI handles a few
+                well known (fixed feature) interrupts sources, such
+                as the power button, it can also handle a variable
+                number of a "General Purpose Events" (GPE).
+
+                A GPE vectors to a specified handler in AML, which
+                can do a anything the BIOS writer wants from
+                OS context.  GPE 0x12, for example, would vector
+                to a level or edge handler called _L12 or _E12.
+                The handler may do its business and return.
+                Or the handler may send send a Notify event
+                to a Linux device driver registered on an ACPI device,
+                such as a battery, or a processor.
+
+                To figure out where all the SCI's are coming from,
+                /sys/firmware/acpi/interrupts contains a file listing
+                every possible source, and the count of how many
+                times it has triggered.
+
+                $ cd /sys/firmware/acpi/interrupts
+                $ grep . *
+                error:0
+                ff_gbl_lock:0
+                ff_pmtimer:0
+                ff_pwr_btn:0
+                ff_rt_clk:0
+                ff_slp_btn:0
+                gpe00:0
+                gpe01:0
+                gpe02:0
+                gpe03:0
+                gpe04:0
+                gpe05:0
+                gpe06:0
+                gpe07:0
+                gpe08:0
+                gpe09:174
+                gpe0A:0
+                gpe0B:0
+                gpe0C:0
+                gpe0D:0
+                gpe0E:0
+                gpe0F:0
+                gpe10:0
+                gpe11:60
+                gpe12:0
+                gpe13:0
+                gpe14:0
+                gpe15:0
+                gpe16:0
+                gpe17:0
+                gpe18:0
+                gpe19:7
+                gpe1A:0
+                gpe1B:0
+                gpe1C:0
+                gpe1D:0
+                gpe1E:0
+                gpe1F:0
+                gpe_all:241
+                sci:241
+
+                sci - The total number of times the ACPI SCI
+                has claimed an interrupt.
+
+                gpe_all - count of SCI caused by GPEs.
+
+                gpeXX - count for individual GPE source
+
+                ff_gbl_lock - Global Lock
+
+                ff_pmtimer - PM Timer
+
+                ff_pwr_btn - Power Button
+
+                ff_rt_clk - Real Time Clock
+
+                ff_slp_btn - Sleep Button
+
+                error - an interrupt that can't be accounted for above.
+
+                Root has permission to clear any of these counters.  Eg.
+                # echo 0 > gpe11
+
+                All counters can be cleared by clearing the total "sci":
+                # echo 0 > sci
+
+                None of these counters has an effect on the function
+                of the system, they are simply statistics.