Intel i945: ACPI: Add _OSC method

Add the ACPI Operating System Capabilities Method and let the
operation system control everything.

Commit »AMD Fam14 DSDT: Add OSC method« (00a0e76b) [1] is used as
a template.

The Lenovo X60 [2] running the Parabola GNU/Linux distribution [3] is
used for testing.

Before that change:

    $ dmesg | egrep -e OSC -e ASPM
    [    0.108036] pci_root PNP0A08:00: ACPI _OSC support notification failed, disabling PCIe ASPM
    [    0.108040] pci_root PNP0A08:00: Unable to request _OSC control (_OSC support mask: 0x08)
    [    0.118089] ACPI _OSC control for PCIe not granted, disabling ASPM
    [   16.874569] e1000e 0000:01:00.0: Disabling ASPM L0s L1

With that change:

    $ dmesg | egrep -e OSC -e ASPM
    [    0.107962] pci_root PNP0A08:00: Requesting ACPI _OSC control (0x1d)
    [    0.108003] pci_root PNP0A08:00: ACPI _OSC control (0x1d) granted
    [    0.111052] pci 0000:01:00.0: disabling ASPM on pre-1.1 PCIe device.  You can enable it with 'pcie_aspm=force'
    [   17.537970] e1000e 0000:01:00.0: Disabling ASPM L0s L1

[1] http://review.coreboot.org/2738
[2] http://www.coreboot.org/Lenovo_x60x
[3] https://parabolagnulinux.org/

Change-Id: I1caffa44eea447d553c01caaf431f2db241ea5ea
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/2938
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
1 file changed