ACPICA: ACPI 6.3: add PCC operation region support for AML interpreter

ACPICA commit a4849944e80f97970e99843f4975850753584a4e

This change adds PCC operation region support in the AML interpreter
and a default handler for acpiexec. According to the specification,
the PCC operation region performs a transaction when the COMD field
is written. This allows ASL to write data to other fields before
sending the data.

In order to accommodate this protocol, a temorary buffer is added
to the regionfield object to accumulate writes. If any offset that
spans COMD is written, the temporary buffer is sent to the PCC
operation region handler to be processed.

This change also renames the PCC keyword to platform_comm_channel.

Link: https://github.com/acpica/acpica/commit/a4849944
Reviewed-by: Kyle Pelton <kyle.d.pelton@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/acobject.h

@@ -239,6 +239,7 @@ struct acpi_object_region_field {
 	union acpi_operand_object *region_obj;	/* Containing op_region object */
 	u8 *resource_buffer;	/* resource_template for serial regions/fields */
 	u16 pin_number_index;	/* Index relative to previous Connection/Template */
+	u8 *internal_pcc_buffer;	/* Internal buffer for fields associated with PCC */
 };
 
 struct acpi_object_bank_field {

drivers/acpi/acpica/dsfield.c

@@ -518,6 +518,13 @@ acpi_ds_create_field(union acpi_parse_object *op,
 	info.region_node = region_node;
 
 	status = acpi_ds_get_field_names(&info, walk_state, arg->common.next);
+	if (info.region_node->object->region.space_id ==
+	    ACPI_ADR_SPACE_PLATFORM_COMM
+	    && !(region_node->object->field.internal_pcc_buffer =
+		 ACPI_ALLOCATE_ZEROED(info.region_node->object->region.
+				      length))) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
 	return_ACPI_STATUS(status);
 }
 

drivers/acpi/acpica/exfield.c

@@ -41,6 +41,17 @@ const u8 acpi_protocol_lengths[] = {
 	0xFF			/* F - ATTRIB_RAW_PROCESS_BYTES */
 };
 
+#define PCC_MASTER_SUBSPACE	3
+
+/*
+ * The following macros determine a given offset is a COMD field.
+ * According to the specification, generic subspaces (types 0-2) contains a
+ * 2-byte COMD field at offset 4 and master subspaces (type 3) contains a 4-byte
+ * COMD field starting at offset 12.
+ */
+#define GENERIC_SUBSPACE_COMMAND(a)	(4 == a || a == 5)
+#define MASTER_SUBSPACE_COMMAND(a)	(12 <= a && a <= 15)
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_ex_get_protocol_buffer_length
@@ -177,6 +188,25 @@ acpi_ex_read_data_from_field(struct acpi_walk_state *walk_state,
 
 		status = acpi_ex_read_gpio(obj_desc, buffer);
 		goto exit;
+	} else if ((obj_desc->common.type == ACPI_TYPE_LOCAL_REGION_FIELD) &&
+		   (obj_desc->field.region_obj->region.space_id ==
+		    ACPI_ADR_SPACE_PLATFORM_COMM)) {
+		/*
+		 * Reading from a PCC field unit does not require the handler because
+		 * it only requires reading from the internal_pcc_buffer.
+		 */
+		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
+				  "PCC FieldRead bits %u\n",
+				  obj_desc->field.bit_length));
+
+		memcpy(buffer,
+		       obj_desc->field.region_obj->field.internal_pcc_buffer +
+		       obj_desc->field.base_byte_offset,
+		       (acpi_size)ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->field.
+							      bit_length));
+
+		*ret_buffer_desc = buffer_desc;
+		return AE_OK;
 	}
 
 	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
@@ -229,6 +259,7 @@ acpi_ex_write_data_to_field(union acpi_operand_object *source_desc,
 {
 	acpi_status status;
 	u32 buffer_length;
+	u32 data_length;
 	void *buffer;
 
 	ACPI_FUNCTION_TRACE_PTR(ex_write_data_to_field, obj_desc);
@@ -272,6 +303,43 @@ acpi_ex_write_data_to_field(union acpi_operand_object *source_desc,
 		    acpi_ex_write_serial_bus(source_desc, obj_desc,
 					     result_desc);
 		return_ACPI_STATUS(status);
+	} else if ((obj_desc->common.type == ACPI_TYPE_LOCAL_REGION_FIELD) &&
+		   (obj_desc->field.region_obj->region.space_id ==
+		    ACPI_ADR_SPACE_PLATFORM_COMM)) {
+		/*
+		 * According to the spec a write to the COMD field will invoke the
+		 * region handler. Otherwise, write to the pcc_internal buffer. This
+		 * implementation will use the offsets specified rather than the name
+		 * of the field. This is considered safer because some firmware tools
+		 * are known to obfiscate named objects.
+		 */
+		data_length =
+		    (acpi_size)ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->field.
+							   bit_length);
+		memcpy(obj_desc->field.region_obj->field.internal_pcc_buffer +
+		       obj_desc->field.base_byte_offset,
+		       source_desc->buffer.pointer, data_length);
+		if ((obj_desc->field.region_obj->region.address ==
+		     PCC_MASTER_SUBSPACE
+		     && MASTER_SUBSPACE_COMMAND(obj_desc->field.
+						base_byte_offset))
+		    || GENERIC_SUBSPACE_COMMAND(obj_desc->field.
+						base_byte_offset)) {
+
+			/* Perform the write */
+
+			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
+					  "PCC COMD field has been written. Invoking PCC handler now.\n"));
+
+			status =
+			    acpi_ex_access_region(obj_desc, 0,
+						  (u64 *)obj_desc->field.
+						  region_obj->field.
+						  internal_pcc_buffer,
+						  ACPI_WRITE);
+			return_ACPI_STATUS(status);
+		}
+		return (AE_OK);
 	}
 
 	/* Get a pointer to the data to be written */

drivers/acpi/acpica/utdelete.c

@@ -257,6 +257,10 @@ static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
 
 			acpi_ut_delete_object_desc(second_desc);
 		}
+		if (object->field.internal_pcc_buffer) {
+			ACPI_FREE(object->field.internal_pcc_buffer);
+		}
+
 		break;
 
 	case ACPI_TYPE_BUFFER_FIELD: