hw/acpi: Add ACPI Generic Event Device Support

hw/acpi: Add ACPI Generic Event Device Support

The ACPI Generic Event Device (GED) is a hardware-reduced specific
device[ACPI v6.1 Section 5.6.9] that handles all platform events,
including the hotplug ones. This patch generates the AML code that
defines GEDs.

Platforms need to specify their own GED Event bitmap to describe
what kind of events they want to support through GED.  Also this
uses a a single interrupt for the  GED device, relying on 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.

This supports only memory hotplug for now.

Signed-off-by: Samuel Ortiz <[email protected]>
Signed-off-by: Sebastien Boeuf <[email protected]>
Signed-off-by: Shameer Kolothum <[email protected]>
Reviewed-by: Eric Auger <[email protected]>
Message-Id: <20190918130633[email protected]>
Acked-by: Peter Maydell <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: Igor Mammedov <[email protected]>