ec/purism/librem: Add ACPI temp reporting

Add EC ACPI reporting of current temp and platform critical temp.
Adapted from ACPI dump of ODM AMI firmware.

TEST: check reporting of current/critical temps via lm-sensors
from ACPI on Librem 13v1 and 13v4 boards.

Change-Id: I92641fbbdda46e0c388607a37f7a7cc2dcd6c26d
Signed-off-by: Matt DeVillier <matt.devillier@puri.sm>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38835
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/ec/purism/librem/acpi/ec.asl

@@ -52,7 +52,9 @@ Device (EC)
 	OperationRegion (ERAM, EmbeddedControl, Zero, 0xFF)
 	Field (ERAM, ByteAcc, Lock, Preserve)
 	{
-		Offset (0x15),
+		Offset (0x13),
+		RTMP, 8,
+		, 8,
 		BSTS, 2,	/* Battery Status */
 		, 3,
 		BTEX, 1,	/* Battery Present */
@@ -231,3 +233,23 @@ Device (EC)
 	#include "ac.asl"
 	#include "battery.asl"
 }
+
+Scope (\_TZ)
+{
+	ThermalZone (TZ0)
+	{
+		/* _TMP: Temperature */
+		Method (_TMP, 0, Serialized)
+		{
+			Local0 = (0x0AAC + (\_SB.PCI0.LPCB.EC.RTMP * 0x0A))
+			Return (Local0)
+		}
+
+		/* _CRT: Critical Temperature */
+		Method (_CRT, 0, Serialized)
+		{
+			/* defined in board ec.asl */
+			Return (CRIT_TEMP)
+		}
+	}
+}

src/mainboard/purism/librem_bdw/acpi/ec.asl

@@ -16,5 +16,6 @@
 #define EC_SCI_GPI 10
 #define PPCM_TURBO Zero
 #define PPCM_NOTURBO One
+#define CRIT_TEMP 105
 
 #include <ec/purism/librem/acpi/ec.asl>

src/mainboard/purism/librem_skl/acpi/ec.asl

@@ -16,5 +16,6 @@
 #define EC_SCI_GPI 0x50
 #define PPCM_TURBO One
 #define PPCM_NOTURBO 0x02
+#define CRIT_TEMP 100
 
 #include <ec/purism/librem/acpi/ec.asl>