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soc/intel/cannonlake: Report driver strength by _DSM in eMMC ACPI device 

According to doc 621880, it suggests setting 40 ohm in byte 185 in extCSD.

This commit provides _DSM method for driver to query driving strength.

TEST=mmc extcsd read |grep HS_TIMING and found bit[7:4] is set to 4
BUG=b:154159888

Signed-off-by: Kane Chen <kane.chen@intel.com>
Change-Id: I1b4df8b0d1d2cad3a7f521ad47ee5a4b3320c767
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40467
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
This commit is contained in:
Kane Chen 2020-04-13 20:48:54 +08:00 committed by Tim Wawrzynczak
parent 007faee948
commit d2b2be3929
1 changed files with 56 additions and 0 deletions
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56
src/soc/intel/cannonlake/acpi/scs.asl
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@ -20,9 +20,12 @@ Scope (\_SB.PCI0) {
Name(_ADR, 0x001A0000)
Name (_DDN, "eMMC Controller")
Name (TEMP, 0)
Name (DSUU, ToUUID("f6c13ea5-65cd-461f-ab7a-29f7e8d5bd61"))
OperationRegion(SCSR, PCI_Config, 0x00, 0x100)
Field(SCSR, WordAcc, NoLock, Preserve) {
Offset (0x0), /* PCI VID DID */
VDID, 32,
Offset (0x84), /* PMECTRLSTATUS */
PMCR, 16,
Offset (0xA2), /* PG_CONFIG */
@ -64,6 +67,59 @@ Scope (\_SB.PCI0) {
Return (0)
}
}
/* _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, ^DSUU)) {
/* Check the revision */
If (LGreaterEqual (Arg1, Zero)) {
/*
* 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
*/
If (LEqual (Arg2, Zero)) {
If (Lequal (VDID, 0x02c48086) ) {
/*
* Set bit 9 for CML eMMC to indicate
* eMMC I/O driver strength is supported
*/
Return(Buffer() {0x0, 0x02})
}
}
/*
* Function Index 9, the return value is preferred eMMC
* driver strength
* 0 - 50 ohm
* 1 - 33 ohm
* 2 - 66 ohm
* 3 - 100 ohm
* 4 - 40 ohm
*/
If (LEqual (Arg2, 9)) {
Return(Buffer() {0x4})
}
}
}
Return(Buffer() { 0x0 })
}
}
/* SD CARD */