SMBus Command Registers

SMBus command set for DMFW (master) <-> CMFW (slave) communication. More...

Enumerations
enum	CMFWSMBusReg {   CMFW_SMBUS_TELEMETRY_READ = 0x02 ,   CMFW_SMBUS_TELEMETRY_WRITE = 0x03 ,   CMFW_SMBUS_UPDATE_ARC_STATE = 0x04 ,   CMFW_SMBUS_REQ = 0x10 ,   CMFW_SMBUS_ACK = 0x11 ,   CMFW_SMBUS_DM_STATIC_INFO = 0x20 ,   CMFW_SMBUS_PING = 0x21 ,   CMFW_SMBUS_FAN_SPEED = 0x22 ,   CMFW_SMBUS_FAN_RPM = 0x23 ,   CMFW_SMBUS_POWER_LIMIT = 0x24 ,   CMFW_SMBUS_POWER_INSTANT = 0x25 ,   CMFW_SMBUS_TELEMETRY_READ_CRC = 0x26 ,   CMFW_SMBUS_TELEMETRY_READ_CRC_DATA = 0x27 ,   CMFW_SMBUS_THERM_TRIP_COUNT = 0x28 ,   CMFW_SMBUS_DMC_LOG = 0x29 ,   CMFW_SMBUS_PING_V2 = 0x2A ,   CMFW_SMBUS_TEST_READ = 0xD8 ,   CMFW_SMBUS_TEST_WRITE = 0xD9 ,   CMFW_SMBUS_TEST_READ_WORD = 0xDA ,   CMFW_SMBUS_TEST_WRITE_WORD = 0xDB ,   CMFW_SMBUS_TEST_READ_BLOCK = 0xDC ,   CMFW_SMBUS_TEST_WRITE_BLOCK = 0xDD ,   CMFW_SMBUS_TEST_WRITE_BLOCK_READ_BLOCK = 0xDE ,   CMFW_SMBUS_MSG_MAX }
	SMBus command codes handled by the CMFW. More...

Detailed Description

SMBus command set for DMFW (master) <-> CMFW (slave) communication.

The DMFW acts as the SMBus master and issues these commands to the CMFW (the SMBus slave). Each command has an access type and a fixed payload size:

• RO (read only): the master reads data from the CMFW.
• WO (write only): the master writes data to the CMFW.
• RW (read/write): a combined transaction where the master writes input bytes and reads response bytes in the same command.

Note

The "Bits In"/"Bits Out" sizes below (and the per-command byte layouts in the enum) count command payload only. They do NOT include SMBus transport framing added on the wire: block-transfer commands carry a leading byte-count byte before the payload, and PEC-enabled commands carry a trailing PEC byte. When a command is driven through the Zephyr SMBus controller API (as production DMFW code does), the controller adds and strips these framing bytes, so callers see only the payload. Tests that instead drive the bus with the raw I2C controller API (i2c_write_read()) observe the full on-wire layout — e.g. a CMFW_SMBUS_REQ read returns 1 count byte + 6 payload bytes (+ a PEC byte if read). Size the receive buffer and parse offsets accordingly.

Enumeration Type Documentation

CMFWSMBusReg

enum CMFWSMBusReg

SMBus command codes handled by the CMFW.

Command	Code	Access	Description
CMFW_SMBUS_TELEMETRY_READ	0x02	RW	Get telemetry data
CMFW_SMBUS_TELEMETRY_WRITE	0x03	RW	Write telemetry data and relay control data
CMFW_SMBUS_UPDATE_ARC_STATE	0x04	WO	Update the ARC state
CMFW_SMBUS_REQ	0x10	RO	Read cm2dmMessage struct describing a request from the CMFW
CMFW_SMBUS_ACK	0x11	WO	Ack a cm2dmMessage with sequence number and message ID
CMFW_SMBUS_DM_STATIC_INFO	0x20	WO	Write dmStaticInfo struct including DMFW version
CMFW_SMBUS_PING	0x21	WO	Write 0xA5A5 to respond to CMFW request kCm2DmMsgIdPing
CMFW_SMBUS_FAN_SPEED	0x22	WO	Target fan speed percentage (0-100) broadcast to every CMFW
CMFW_SMBUS_FAN_RPM	0x23	WO	Fan speed response to CMFW fan-speed-update requests
CMFW_SMBUS_POWER_LIMIT	0x24	WO	Input power limit for the board
CMFW_SMBUS_POWER_INSTANT	0x25	WO	Current input power for the board
CMFW_SMBUS_TELEMETRY_READ_CRC	0x26	WO	Select a telemetry tag for reading
CMFW_SMBUS_TELEMETRY_READ_CRC_DATA	0x27	RO	Read telemetry payload and response metadata after selecting a tag
CMFW_SMBUS_THERM_TRIP_COUNT	0x28	WO	Thermal trip count
CMFW_SMBUS_DMC_LOG	0x29	WO	Up to 32 bytes of data to log from the DMC side
CMFW_SMBUS_PING_V2	0x2A	RO	Read data to verify the SMC got this ping request
CMFW_SMBUS_TEST_READ	0xD8	RO	Test read from CMFW scratch register
CMFW_SMBUS_TEST_WRITE	0xD9	WO	Test write to CMFW scratch register
CMFW_SMBUS_TEST_READ_WORD	0xDA	RO	Test read from CMFW scratch register
CMFW_SMBUS_TEST_WRITE_WORD	0xDB	WO	Test write to CMFW scratch register
CMFW_SMBUS_TEST_READ_BLOCK	0xDC	RO	Test read from CMFW scratch register
CMFW_SMBUS_TEST_WRITE_BLOCK	0xDD	WO	Test write to CMFW scratch register
CMFW_SMBUS_TEST_WRITE_BLOCK_READ_BLOCK	0xDE	RW	Test write to CMFW scratch register and read it back

Enumerator
CMFW_SMBUS_TELEMETRY_READ	0x02	Get telemetry data. Input (1 byte): byte 0: telemetry tag (register index) selecting which value to read. Output (7 bytes, little-endian): byte 0: tag valid flag (0 = valid, 1 = tag out of range). bytes 1-2: reserved (0). bytes 3-6: 32-bit telemetry value for the tag (0xFFFFFFFF if invalid).
CMFW_SMBUS_TELEMETRY_WRITE	0x03	Write telemetry data and relay control data. Input (33 bytes): telemetry payload from the DMC. The CMFW currently validates only the length and does not interpret the contents. Output (20 bytes, little-endian): bytes 0-10: reserved (0). bytes 11-14: control-data bitfield (LSB first): bit 0-7: pcie_index. bit 8: trigger_asic_reset. bit 9: trigger_spi_copy_1_to_r. bit 10: arc_state_a3_req. bit 11: arc_state_a0_req. bit 12: trigger_asic_and_m3_reset. bit 13: clear_num_auto_reset. bit 14-31: spare. bytes 15-18: reserved (0). byte 19: CRC-8 PEC (poly 0x7) over the size byte and bytes 0-18. Not SMBus-compliant; kept for WH compatibility.
CMFW_SMBUS_UPDATE_ARC_STATE	0x04	Update the ARC state. Input (3 bytes): byte 0: ASIC state value. byte 1: signature, must be 0xDE. byte 2: signature, must be 0xAF.
CMFW_SMBUS_REQ	0x10	Read cm2dmMessage struct describing a request from the CMFW. Output (6 bytes, little-endian), a cm2dmMessage struct: byte 0: msg_id (a Cm2DmMsgId, e.g. reset / ping / fan-speed request). byte 1: seq_num (incremented per issued message). bytes 2-5: data (message-specific 32-bit payload). All bytes are zero when no message is pending.
CMFW_SMBUS_ACK	0x11	Ack a cm2dmMessage with sequence number and message ID. Input (2 bytes), a cm2dmAck struct: byte 0: msg_id (must match the pending message's msg_id). byte 1: seq_num (must match the pending message's seq_num). On a match the pending cm2dmMessage is cleared.
CMFW_SMBUS_DM_STATIC_INFO	0x20	Write dmStaticInfo struct including DMFW version. Input (24 bytes, little-endian), a dmStaticInfo of six uint32 fields: bytes 0-3: version (must be non-zero, else the write is rejected). bytes 4-7: bl_version (bootloader version). bytes 8-11: app_version (application version). bytes 12-15: arc_start_time (timestamp in ASIC refclk @ 50 MHz). bytes 16-19: dm_init_duration (duration in DMC refclk @ 64 MHz). bytes 20-23: arc_hang_pc (PC of last ARC hang; recorded only if non-zero).
CMFW_SMBUS_PING	0x21	Write 0xA5A5 to respond to CMFW request kCm2DmMsgIdPing. Input (2 bytes): 16-bit value, must equal 0xA5A5 (little-endian). Responds to the CMFW request kCm2DmMsgIdPing.
CMFW_SMBUS_FAN_SPEED	0x22	Target fan speed percentage (0-100) broadcast to every CMFW. Input (2 bytes): 16-bit target fan speed percentage (0-100), little-endian. Broadcast by the DMFW to every CMFW so each chip's telemetry reflects the board-level setting.
CMFW_SMBUS_FAN_RPM	0x23	Fan speed response to CMFW fan-speed-update requests. Input (2 bytes): 16-bit fan speed in RPM, little-endian. Responds to the CMFW request kCm2DmMsgIdFanSpeedUpdate or kCm2DmMsgIdForcedFanSpeedUpdate.
CMFW_SMBUS_POWER_LIMIT	0x24	Input power limit for the board. Input (2 bytes): 16-bit board input power limit (little-endian). Clamped to the board limit and applied to the board-power and Doppler-slow throttlers.
CMFW_SMBUS_POWER_INSTANT	0x25	Current input power for the board. Input (2 bytes): 16-bit current input power (little-endian). Stored with an additional board-power offset added and triggers a DVFS timer adjustment.
CMFW_SMBUS_TELEMETRY_READ_CRC	0x26	Select a telemetry tag for reading. Input (1 byte): byte 0: telemetry tag to select for the subsequent CMFW_SMBUS_TELEMETRY_READ_CRC_DATA read. This command itself returns no data; the value is read back with the separate CMFW_SMBUS_TELEMETRY_READ_CRC_DATA (0x27) command. "CRC" refers to the transport PEC byte appended by the SMBus layer, not a CRC computed by the handler.
CMFW_SMBUS_TELEMETRY_READ_CRC_DATA	0x27	Read telemetry payload and response metadata after selecting a tag. Output (7 bytes, little-endian), same layout as CMFW_SMBUS_TELEMETRY_READ: byte 0: tag valid flag (0 = valid, 1 = tag out of range). bytes 1-2: reserved (0). bytes 3-6: 32-bit telemetry value for the selected tag.
CMFW_SMBUS_THERM_TRIP_COUNT	0x28	Thermal trip count. Input (2 bytes): 16-bit thermal trip count, little-endian.
CMFW_SMBUS_DMC_LOG	0x29	Up to 32 bytes of data to log from the DMC side. Input (variable, up to 32 bytes): raw log characters written to the DMC vUART; no structured fields.
CMFW_SMBUS_PING_V2	0x2A	Read data to verify the SMC got this ping request. Output (2 bytes): fixed sentinel 0xA5, 0xA5. Read to verify the SMC received this ping request.
CMFW_SMBUS_TEST_READ	0xD8	Test read from CMFW scratch register. Output (1 byte): low byte of the CMFW scratch register.
CMFW_SMBUS_TEST_WRITE	0xD9	Test write to CMFW scratch register. Input (1 byte): value written to the CMFW scratch register.
CMFW_SMBUS_TEST_READ_WORD	0xDA	Test read from CMFW scratch register. Output (2 bytes): low 16 bits of the scratch register, little-endian.
CMFW_SMBUS_TEST_WRITE_WORD	0xDB	Test write to CMFW scratch register. Input (2 bytes): value written to the scratch register, little-endian.
CMFW_SMBUS_TEST_READ_BLOCK	0xDC	Test read from CMFW scratch register. Output (4 bytes): full 32-bit scratch register, little-endian.
CMFW_SMBUS_TEST_WRITE_BLOCK	0xDD	Test write to CMFW scratch register. Input (4 bytes): value written to the scratch register, little-endian.
CMFW_SMBUS_TEST_WRITE_BLOCK_READ_BLOCK	0xDE	Test write to CMFW scratch register and read it back. Input (4 bytes): value written to the scratch register, little-endian. Output (4 bytes): the value read back, little-endian.
CMFW_SMBUS_MSG_MAX		One past the last defined command code; not a real command. The command codes above are sparse, so this is not a count of commands. It is used as a known-invalid command code (e.g. in the smbus_target tests).