[coreboot-gerrit] Change in ...coreboot[master]: soc/intel/cannonlake: Add _DSM method for SD controller

[Evan Green (Code Review)]

Hello V Sowmya,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/33233

to review the following change.

Change subject: soc/intel/cannonlake: Add _DSM method for SD controller
......................................................................

soc/intel/cannonlake: Add _DSM method for SD controller

Change-Id: I15090ed9f9bc90b35dfcba47c913e3d37b799d0b
Signed-off-by: V Sowmya 
---
M src/soc/intel/cannonlake/acpi/scs.asl
1 file changed, 61 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/33/33233/1

diff --git a/src/soc/intel/cannonlake/acpi/scs.asl b/src/soc/intel/cannonlake/acpi/scs.asl
index cdfff91..924228e 100644
--- a/src/soc/intel/cannonlake/acpi/scs.asl
+++ b/src/soc/intel/cannonlake/acpi/scs.asl
@@ -95,6 +95,67 @@
    		PGEN, 1,	/* PG_ENABLE */
    	}

+		/* _DSM x86 Device Specific Method
+		 * Arg0: UUID Unique function identifier
+		 * Arg1: Integer Revision Level
+		 * Arg2: Integer Function Index (0 = Return Supported Functions)
+		 * Arg3: Package Parameters
+		 */
+		Method (_DSM, 4)
+		{
+			If(LEqual(Arg0, ToUUID("f6c13ea5-65cd-461f-ab7a-29f7e8d5bd61"))) {
+				/* Check the revision */
+				If(LGreaterEqual(Arg1, Zero)) {
+					/* Switch statement based on the function index. */
+					Switch(ToInteger(Arg2)) {
+					/*
+					 * Function Index 0 the return value is a buffer containing
+					 * one bit for each function index, starting with zero.
+					 * Bit 0 - Indicates whether there is support for any functions other than function 0.
+					 * Bit 1 - Indicates support to clear power control register
+					 * Bit 2 - Indicates support to set power control register
+					 * Bit 3 - Indicates support to set 1.8V signalling
+					 * Bit 4 - Indicates support to set 3.3V signalling
+					 * Bit 5 - Indicates support for HS200 mode
+					 * Bit 6 - Indicates support for HS400 mode
+					 * Bit 9 - Indicates eMMC I/O Driver Strength
+					 */
+					/*
+					 * For SD we have to support functions to
+					 * set 1.8V signalling and 3.3V signalling [BIT4, BIT3]
+					 */
+					Case(0) {
+						Return (Buffer() {0x19})
+					}
+
+					/*
+					 * Function Index 3: Set 1.8v signalling.
+					 * We put a sleep of 100ms in this method to
+					 * work around a known issue with detecting
+					 * UHS SD card on PCH. This is to compensate
+					 * for the SD VR slowness.
+					 */
+					Case(3) {
+						Sleep (100) // Sleep 100ms
+						Return(Buffer(){0x00})
+					}
+					/*
+					 * Function Index 4: Set 3.3v signalling.
+					 * We put a sleep of 100ms in this method to
+					 * work around a known issue with detecting
+					 * UHS SD card on PCH. This is to compensate
+					 * for the SD VR slowness.
+					 */
+					Case(4) {
+						Sleep (100) // Sleep 100ms
+						Return(Buffer(){0x00})
+					}
+				} // End - Switch(Arg2)
+				}
+			} // End - UUID check
+			Return(Buffer() {0x0})
+		} // End _DSM
+
    	Method(_INI)
    	{
    		/* Clear register 0x1C20/0x4820 */