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

[linux-2.6-omap-h63xx.git] / Documentation / ABI / testing / sysfs-firmware-acpi

diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi
index 9470ed9afcc07238077440312c24af3d5ef88ad0..f27be7d1a49f4038951827c583734b1cf1be3125 100644 (file)
--- 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
+