71b58cbb0c
Allow users to enable/disable/clear a specific & valid GPE/Fixed Event in user space. This is useful for debugging, especially for some interrupt storm issues. All wakeup GPEs are disabled and they can not be enabled at runtime, and we mark them as invalid. All GPEs that don't have a _Lxx/_Exx method are marked as invalid. All Fixed Events that don't have an event handler are marked as invalid and they can't be enabled until an event handler is registered. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Ling Ming <ming.m.lin@intel.com> Signed-off-by: Len Brown <len.brown@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
147 lines
4.1 KiB
Plaintext
147 lines
4.1 KiB
Plaintext
What: /sys/firmware/acpi/interrupts/
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Date: February 2008
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Contact: Len Brown <lenb@kernel.org>
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Description:
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All ACPI interrupts are handled via a single IRQ,
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the System Control Interrupt (SCI), which appears
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as "acpi" in /proc/interrupts.
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However, one of the main functions of ACPI is to make
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the platform understand random hardware without
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special driver support. So while the SCI handles a few
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well known (fixed feature) interrupts sources, such
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as the power button, it can also handle a variable
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number of a "General Purpose Events" (GPE).
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A GPE vectors to a specified handler in AML, which
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can do a anything the BIOS writer wants from
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OS context. GPE 0x12, for example, would vector
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to a level or edge handler called _L12 or _E12.
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The handler may do its business and return.
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Or the handler may send send a Notify event
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to a Linux device driver registered on an ACPI device,
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such as a battery, or a processor.
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To figure out where all the SCI's are coming from,
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/sys/firmware/acpi/interrupts contains a file listing
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every possible source, and the count of how many
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times it has triggered.
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$ cd /sys/firmware/acpi/interrupts
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$ grep . *
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error: 0
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ff_gbl_lock: 0 enable
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ff_pmtimer: 0 invalid
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ff_pwr_btn: 0 enable
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ff_rt_clk: 2 disable
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ff_slp_btn: 0 invalid
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gpe00: 0 invalid
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gpe01: 0 enable
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gpe02: 108 enable
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gpe03: 0 invalid
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gpe04: 0 invalid
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gpe05: 0 invalid
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gpe06: 0 enable
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gpe07: 0 enable
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gpe08: 0 invalid
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gpe09: 0 invalid
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gpe0A: 0 invalid
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gpe0B: 0 invalid
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gpe0C: 0 invalid
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gpe0D: 0 invalid
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gpe0E: 0 invalid
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gpe0F: 0 invalid
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gpe10: 0 invalid
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gpe11: 0 invalid
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gpe12: 0 invalid
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gpe13: 0 invalid
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gpe14: 0 invalid
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gpe15: 0 invalid
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gpe16: 0 invalid
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gpe17: 1084 enable
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gpe18: 0 enable
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gpe19: 0 invalid
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gpe1A: 0 invalid
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gpe1B: 0 invalid
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gpe1C: 0 invalid
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gpe1D: 0 invalid
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gpe1E: 0 invalid
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gpe1F: 0 invalid
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gpe_all: 1192
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sci: 1194
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sci - The total number of times the ACPI SCI
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has claimed an interrupt.
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gpe_all - count of SCI caused by GPEs.
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gpeXX - count for individual GPE source
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ff_gbl_lock - Global Lock
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ff_pmtimer - PM Timer
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ff_pwr_btn - Power Button
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ff_rt_clk - Real Time Clock
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ff_slp_btn - Sleep Button
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error - an interrupt that can't be accounted for above.
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invalid: it's either a wakeup GPE or a GPE/Fixed Event that
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doesn't have an event handler.
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disable: the GPE/Fixed Event is valid but disabled.
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enable: the GPE/Fixed Event is valid and enabled.
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Root has permission to clear any of these counters. Eg.
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# echo 0 > gpe11
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All counters can be cleared by clearing the total "sci":
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# echo 0 > sci
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None of these counters has an effect on the function
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of the system, they are simply statistics.
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Besides this, user can also write specific strings to these files
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to enable/disable/clear ACPI interrupts in user space, which can be
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used to debug some ACPI interrupt storm issues.
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Note that only writting to VALID GPE/Fixed Event is allowed,
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i.e. user can only change the status of runtime GPE and
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Fixed Event with event handler installed.
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Let's take power button fixed event for example, please kill acpid
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and other user space applications so that the machine won't shutdown
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when pressing the power button.
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# cat ff_pwr_btn
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0
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# press the power button for 3 times;
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# cat ff_pwr_btn
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3
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# echo disable > ff_pwr_btn
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# cat ff_pwr_btn
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disable
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# press the power button for 3 times;
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# cat ff_pwr_btn
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disable
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# echo enable > ff_pwr_btn
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# cat ff_pwr_btn
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4
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/*
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* this is because the status bit is set even if the enable bit is cleared,
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* and it triggers an ACPI fixed event when the enable bit is set again
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*/
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# press the power button for 3 times;
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# cat ff_pwr_btn
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7
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# echo disable > ff_pwr_btn
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# press the power button for 3 times;
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# echo clear > ff_pwr_btn /* clear the status bit */
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# echo disable > ff_pwr_btn
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# cat ff_pwr_btn
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7
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