acpi: Map EC features into ACPI EC memory space

Reserve EC address space offset 0x0a-0x0d for device features. Same
value as with the host command, just different way to access it.

BUG=b:64705535
BRANCH=none
TEST=none

Change-Id: I420aed1ae8d0fb7da477fc72ac55ea75a9f9350b
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/626976
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Duncan Laurie <dlaurie@google.com>

3 files changed, 48 insertions, 1 deletions

diff --git a/common/acpi.c b/common/acpi.c
index d9815100e1..2097beeda8 100644
--- a/common/acpi.c
+++ b/common/acpi.c
@@ -175,6 +175,32 @@ int acpi_ap_to_ec(int is_cmd, uint8_t value, uint8_t *resultptr)
 			break;
 #endif
 
+		case EC_ACPI_MEM_DEVICE_FEATURES0:
+		case EC_ACPI_MEM_DEVICE_FEATURES1:
+		case EC_ACPI_MEM_DEVICE_FEATURES2:
+		case EC_ACPI_MEM_DEVICE_FEATURES3: {
+			int off = acpi_addr - EC_ACPI_MEM_DEVICE_FEATURES0;
+			uint32_t val = get_feature_flags0();
+
+			/* Flush EC_FEATURE_LIMITED bit. Having it reset to 0
+			 * means that FEATURES[0-3] are supported in the first
+			 * place, and the other bits are valid.
+			 */
+			val &= ~1;
+
+			result = val >> (8 * off);
+			break;
+			}
+		case EC_ACPI_MEM_DEVICE_FEATURES4:
+		case EC_ACPI_MEM_DEVICE_FEATURES5:
+		case EC_ACPI_MEM_DEVICE_FEATURES6:
+		case EC_ACPI_MEM_DEVICE_FEATURES7: {
+			int off = acpi_addr - EC_ACPI_MEM_DEVICE_FEATURES4;
+			uint32_t val = get_feature_flags1();
+
+			result = val >> (8 * off);
+			break;
+			}
 		default:
 			result = acpi_read(acpi_addr);
 			break;
diff --git a/common/build.mk b/common/build.mk
index ba8dee4c5d..0e0b8ff66e 100644
--- a/common/build.mk
+++ b/common/build.mk
@@ -77,7 +77,7 @@ common-$(CONFIG_LED_POLICY_STD)+=led_policy_std.o
 common-$(CONFIG_LID_ANGLE)+=motion_lid.o math_util.o
 common-$(CONFIG_LID_ANGLE_UPDATE)+=lid_angle.o
 common-$(CONFIG_LID_SWITCH)+=lid_switch.o
-common-$(CONFIG_LPC)+=acpi.o port80.o
+common-$(CONFIG_LPC)+=acpi.o port80.o ec_features.o
 common-$(CONFIG_MAG_CALIBRATE)+= mag_cal.o math_util.o vec3.o mat33.o mat44.o
 common-$(CONFIG_MKBP_EVENT)+=mkbp_event.o
 common-$(CONFIG_ONEWIRE)+=onewire.o
diff --git a/include/ec_commands.h b/include/ec_commands.h
index 8be7a4df8a..633640defd 100644
--- a/include/ec_commands.h
+++ b/include/ec_commands.h
@@ -326,6 +326,27 @@
 #define EC_ACPI_MEM_DEVICE_TABLET_MODE 0x01
 
 /*
+ * Report device features. Uses the same format as the host command, except:
+ *
+ * bit 0 (EC_FEATURE_LIMITED) changes meaning from "EC code has a limited set
+ * of features", which is of limited interest when the system is already
+ * interpreting ACPI bytecode, to "EC_FEATURES[0-7] is not supported". Since
+ * these are supported, it defaults to 0.
+ * This allows detecting the presence of this field since older versions of
+ * the EC codebase would simply return 0xff to that unknown address. Check
+ * FEATURES0 != 0xff (or FEATURES0[0] == 0) to make sure that the other bits
+ * are valid.
+ */
+#define EC_ACPI_MEM_DEVICE_FEATURES0 0x0a
+#define EC_ACPI_MEM_DEVICE_FEATURES1 0x0b
+#define EC_ACPI_MEM_DEVICE_FEATURES2 0x0c
+#define EC_ACPI_MEM_DEVICE_FEATURES3 0x0d
+#define EC_ACPI_MEM_DEVICE_FEATURES4 0x0e
+#define EC_ACPI_MEM_DEVICE_FEATURES5 0x0f
+#define EC_ACPI_MEM_DEVICE_FEATURES6 0x10
+#define EC_ACPI_MEM_DEVICE_FEATURES7 0x11
+
+/*
  * ACPI addresses 0x20 - 0xff map to EC_MEMMAP offset 0x00 - 0xdf.  This data
  * is read-only from the AP.  Added in EC_ACPI_MEM_VERSION 2.
  */