ACPI: create /sys/firmware/acpi/interrupts
See Documentation/ABI/testing/sysfs-firmware-acpi
Based-on-original-patch-by: Luming Yu <luming.yu@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi
new file mode 100644
index 0000000..9470ed9
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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.