ACPI: Enhance /sys/firmware/interrupts to allow enable/disable/clear from user-space

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>

1 files changed, 87 insertions, 40 deletions

diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi
index 9470ed9afcc..f27be7d1a49 100644
--- a/Documentation/ABI/testing/sysfs-firmware-acpi
+++ b/Documentation/ABI/testing/sysfs-firmware-acpi
@@ -29,46 +29,46 @@ Description:
 
 		$ 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
+		error:	     0
+		ff_gbl_lock:	   0   enable
+		ff_pmtimer:	  0  invalid
+		ff_pwr_btn:	  0   enable
+		ff_rt_clk:	 2  disable
+		ff_slp_btn:	  0  invalid
+		gpe00:	     0	invalid
+		gpe01:	     0	 enable
+		gpe02:	   108	 enable
+		gpe03:	     0	invalid
+		gpe04:	     0	invalid
+		gpe05:	     0	invalid
+		gpe06:	     0	 enable
+		gpe07:	     0	 enable
+		gpe08:	     0	invalid
+		gpe09:	     0	invalid
+		gpe0A:	     0	invalid
+		gpe0B:	     0	invalid
+		gpe0C:	     0	invalid
+		gpe0D:	     0	invalid
+		gpe0E:	     0	invalid
+		gpe0F:	     0	invalid
+		gpe10:	     0	invalid
+		gpe11:	     0	invalid
+		gpe12:	     0	invalid
+		gpe13:	     0	invalid
+		gpe14:	     0	invalid
+		gpe15:	     0	invalid
+		gpe16:	     0	invalid
+		gpe17:	  1084	 enable
+		gpe18:	     0	 enable
+		gpe19:	     0	invalid
+		gpe1A:	     0	invalid
+		gpe1B:	     0	invalid
+		gpe1C:	     0	invalid
+		gpe1D:	     0	invalid
+		gpe1E:	     0	invalid
+		gpe1F:	     0	invalid
+		gpe_all:    1192
+		sci:	1194
 
 		sci - The total number of times the ACPI SCI
 		has claimed an interrupt.
@@ -89,6 +89,13 @@ Description:
 
 		error - an interrupt that can't be accounted for above.
 
+		invalid: it's either a wakeup GPE or a GPE/Fixed Event that
+			doesn't have an event handler.
+
+		disable: the GPE/Fixed Event is valid but disabled.
+
+		enable: the GPE/Fixed Event is valid and enabled.
+
 		Root has permission to clear any of these counters.  Eg.
 		# echo 0 > gpe11
 
@@ -97,3 +104,43 @@ Description:
 
 		None of these counters has an effect on the function
 		of the system, they are simply statistics.
+
+		Besides this, user can also write specific strings to these files
+		to enable/disable/clear ACPI interrupts in user space, which can be
+		used to debug some ACPI interrupt storm issues.
+
+		Note that only writting to VALID GPE/Fixed Event is allowed,
+		i.e. user can only change the status of runtime GPE and
+		Fixed Event with event handler installed.
+
+		Let's take power button fixed event for example, please kill acpid
+		and other user space applications so that the machine won't shutdown
+		when pressing the power button.
+		# cat ff_pwr_btn
+		0
+		# press the power button for 3 times;
+		# cat ff_pwr_btn
+		3
+		# echo disable > ff_pwr_btn
+		# cat ff_pwr_btn
+		disable
+		# press the power button for 3 times;
+		# cat ff_pwr_btn
+		disable
+		# echo enable > ff_pwr_btn
+		# cat ff_pwr_btn
+		4
+		/*
+		 * this is because the status bit is set even if the enable bit is cleared,
+		 * and it triggers an ACPI fixed event when the enable bit is set again
+		 */
+		# press the power button for 3 times;
+		# cat ff_pwr_btn
+		7
+		# echo disable > ff_pwr_btn
+		# press the power button for 3 times;
+		# echo clear > ff_pwr_btn	/* clear the status bit */
+		# echo disable > ff_pwr_btn
+		# cat ff_pwr_btn
+		7
+