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Diffstat (limited to 'Documentation/ABI/testing/sysfs-firmware-acpi')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-firmware-acpi | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi new file mode 100644 index 00000000..dd930c8d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-acpi @@ -0,0 +1,170 @@ +What: /sys/firmware/acpi/bgrt/ +Date: January 2012 +Contact: Matthew Garrett <mjg@redhat.com> +Description: + The BGRT is an ACPI 5.0 feature that allows the OS + to obtain a copy of the firmware boot splash and + some associated metadata. This is intended to be used + by boot splash applications in order to interact with + the firmware boot splash in order to avoid jarring + transitions. + + image: The image bitmap. Currently a 32-bit BMP. + status: 1 if the image is valid, 0 if firmware invalidated it. + type: 0 indicates image is in BMP format. + version: The version of the BGRT. Currently 1. + xoffset: The number of pixels between the left of the screen + and the left edge of the image. + yoffset: The number of pixels between the top of the screen + and the top edge of the image. + +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 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_not: 0 + + sci - The number of times the ACPI SCI + has been called and claimed an interrupt. + + sci_not - The number of times the ACPI SCI + has been called and NOT 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. + + invalid: it's either a GPE or a 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 + + 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. + + 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 enabled + # press the power button for 3 times; + # cat ff_pwr_btn + 3 enabled + # echo disable > ff_pwr_btn + # cat ff_pwr_btn + 3 disabled + # press the power button for 3 times; + # cat ff_pwr_btn + 3 disabled + # echo enable > ff_pwr_btn + # cat ff_pwr_btn + 4 enabled + /* + * 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 enabled + # 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 enabled + |