mirror of https://gitlab.com/qemu-project/qemu
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
73 lines
2.1 KiB
ReStructuredText
73 lines
2.1 KiB
ReStructuredText
==================================================
|
|
QEMU and ACPI BIOS Generic Event Device interface
|
|
==================================================
|
|
|
|
The ACPI *Generic Event Device* (GED) is a HW reduced platform
|
|
specific device introduced in ACPI v6.1 that handles all platform
|
|
events, including the hotplug ones. GED is modelled as a device
|
|
in the namespace with a _HID defined to be ACPI0013. This document
|
|
describes the interface between QEMU and the ACPI BIOS.
|
|
|
|
GED allows HW reduced platforms to handle interrupts in ACPI ASL
|
|
statements. It follows a very similar approach to the _EVT method
|
|
from GPIO events. All interrupts are listed in _CRS and the handler
|
|
is written in _EVT method. However, the QEMU implementation uses a
|
|
single interrupt for the GED device, relying on an IO memory region
|
|
to communicate the type of device affected by the interrupt. This way,
|
|
we can support up to 32 events with a unique interrupt.
|
|
|
|
**Here is an example,**
|
|
|
|
::
|
|
|
|
Device (\_SB.GED)
|
|
{
|
|
Name (_HID, "ACPI0013")
|
|
Name (_UID, Zero)
|
|
Name (_CRS, ResourceTemplate ()
|
|
{
|
|
Interrupt (ResourceConsumer, Edge, ActiveHigh, Exclusive, ,, )
|
|
{
|
|
0x00000029,
|
|
}
|
|
})
|
|
OperationRegion (EREG, SystemMemory, 0x09080000, 0x04)
|
|
Field (EREG, DWordAcc, NoLock, WriteAsZeros)
|
|
{
|
|
ESEL, 32
|
|
}
|
|
Method (_EVT, 1, Serialized)
|
|
{
|
|
Local0 = ESEL // ESEL = IO memory region which specifies the
|
|
// device type.
|
|
If (((Local0 & One) == One))
|
|
{
|
|
MethodEvent1()
|
|
}
|
|
If ((Local0 & 0x2) == 0x2)
|
|
{
|
|
MethodEvent2()
|
|
}
|
|
...
|
|
}
|
|
}
|
|
|
|
GED IO interface (4 byte access)
|
|
--------------------------------
|
|
**read access:**
|
|
|
|
::
|
|
|
|
[0x0-0x3] Event selector bit field (32 bit) set by QEMU.
|
|
|
|
bits:
|
|
0: Memory hotplug event
|
|
1: System power down event
|
|
2: NVDIMM hotplug event
|
|
3: CPU hotplug event
|
|
4-31: Reserved
|
|
|
|
**write_access:**
|
|
|
|
Nothing is expected to be written into GED IO memory
|