linux-next/include/linux/prmt.h

/* SPDX-License-Identifier: GPL-2.0-only */

#ifdef CONFIG_ACPI_PRMT
void init_prmt(void);
#else
static inline void init_prmt(void) { }
#endif
ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype Platform Runtime Mechanism (PRM) is a firmware interface that exposes a set of binary executables that can either be called from the AML interpreter or device drivers by bypassing the AML interpreter. This change implements the AML interpreter path. According to the specification [1], PRM services are listed in an ACPI table called the PRMT. This patch parses module and handler information listed in the PRMT and registers the PlatformRtMechanism OpRegion handler before ACPI tables are loaded. Each service is defined by a 16-byte GUID and called from writing a 26-byte ASL buffer containing the identifier to a FieldUnit object defined inside a PlatformRtMechanism OperationRegion. OperationRegion (PRMR, PlatformRtMechanism, 0, 26) Field (PRMR, BufferAcc, NoLock, Preserve) { PRMF, 208 // Write to this field to invoke the OperationRegion Handler } The 26-byte ASL buffer is defined as the following: Byte Offset Byte Length Description ============================================================= 0 1 PRM OperationRegion handler status 1 8 PRM service status 9 1 PRM command 10 16 PRM handler GUID The ASL caller fills out a 26-byte buffer containing the PRM command and the PRM handler GUID like so: /* Local0 is the PRM data buffer / Local0 = buffer (26){} / Create byte fields over the buffer / CreateByteField (Local0, 0x9, CMD) CreateField (Local0, 0x50, 0x80, GUID) / Fill in the command and data fields of the data buffer / CMD = 0 // run command GUID = ToUUID("xxxx-xx-xxx-xxxx") / * Invoke PRM service with an ID that matches GUID and save the * result. / Local0 = (\_SB.PRMT.PRMF = Local0) Byte offset 0 - 8 are written by the handler as a status passed back to AML and used by ASL like so: / Create byte fields over the buffer */ CreateByteField (Local0, 0x0, PSTA) CreateQWordField (Local0, 0x1, USTA) In this ASL code, PSTA contains a status from the OperationRegion and USTA contains a status from the PRM service. The 26-byte buffer is recieved by acpi_platformrt_space_handler. This handler will look at the command value and the handler guid and take the approperiate actions. Command value Action ===================================================================== 0 Run the PRM service indicated by the PRM handler GUID (bytes 10-26) 1 Prevent PRM runtime updates from happening to the service's parent module 2 Allow PRM updates from happening to the service's parent module This patch enables command value 0. Link: https://uefi.org/sites/default/files/resources/Platform%20Runtime%20Mechanism%20-%20with%20legal%20notice.pdf # [1] Signed-off-by: Erik Kaneda <erik.kaneda@intel.com> [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 2021-06-09 20:41:52 -07:00			`/* SPDX-License-Identifier: GPL-2.0-only */`

			`#ifdef CONFIG_ACPI_PRMT`
			`void init_prmt(void);`
			`#else`
			`static inline void init_prmt(void) { }`
			`#endif`