[coreboot] New patch to review for coreboot: 11b7528 Persimmon DSDT: Add OSC method

Mike Loptien (mike.loptien@se-eng.com) gerrit at coreboot.org
Wed Mar 13 00:30:27 CET 2013

Mike Loptien (mike.loptien at se-eng.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2684


commit 11b7528420451d75da381e77e9fdadf417d16451
Author: Mike Loptien <mike.loptien at se-eng.com>
Date:   Tue Mar 12 10:21:24 2013 -0600

    Persimmon DSDT: Add OSC method
    The _OSC method is used to tell the OS what capabilities
    it can take control over from the firmware.  This method
    is described in chapter 6.2.9 of the ACPI spec v3.0.
    The method takes 4 inputs (UUID, Rev ID, Input Count,
    and Capabilities Buffer) and returns a Capabilites
    Buffer the same size as the input Buffer.  This Buffer
    is generally 3 Dwords long consisting of an Errors
    Dword, a Supported Capabilities Dword, and a Control
    Dword.  The OS will request control of certain
    capabilities and the firmware must grant or deny control
    of those features.  We do not want to have control over
    anything so let the OS control as much as it can.
    The _OSC method is required for PCIe devices and dmesg
    checks for its existence and issues an error if it is
    not found.
    Change-Id: I1494285def7440972f0549b7cb73eb94dafc72c2
    Signed-off-by: Mike Loptien <mike.loptien at se-eng.com>
 src/mainboard/amd/persimmon/dsdt.asl | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/mainboard/amd/persimmon/dsdt.asl b/src/mainboard/amd/persimmon/dsdt.asl
index 148d7b0..dff5917 100644
--- a/src/mainboard/amd/persimmon/dsdt.asl
+++ b/src/mainboard/amd/persimmon/dsdt.asl
@@ -1157,8 +1157,20 @@ DefinitionBlock (
 		Device(PCI0) {
 			External (TOM1)
 			External (TOM2)
-			Name(_HID, EISAID("PNP0A03"))
+			Name(_HID, EISAID("PNP0A08"))	/* PCI Express Root Bridge */
+			Name(_CID, EISAID("PNP0A03"))	/* PCI Root Bridge */
 			Name(_ADR, 0x00180000)	/* Dev# = BSP Dev#, Func# = 0 */
+			/* Operating System Capabilities Method */
+			Method(_OSC,4)
+			{	/* Check for proper PCI/PCIe UUID */
+				If(LEqual(Arg0,ToUUID("33DB4D5B-1FF7-401C-9657-7441C03DD766")))
+				{
+					/* Let OS control everything */
+					Return (Arg3)
+				}
+			}
 			Method(_BBN, 0) { /* Bus number = 0 */

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