1.\" 2.\" This file and its contents are supplied under the terms of the 3.\" Common Development and Distribution License ("CDDL"), version 1.0. 4.\" You may only use this file in accordance with the terms of version 5.\" 1.0 of the CDDL. 6.\" 7.\" A full copy of the text of the CDDL should have accompanied this 8.\" source. A copy of the CDDL is also available via the Internet at 9.\" http://www.illumos.org/license/CDDL. 10.\" 11.\" 12.\" Copyright 2025 Oxide Computer Company 13.\" 14.Dd September 21, 2025 15.Dt SPD511X 4D 16.Os 17.Sh NAME 18.Nm spd511x 19.Nd DDR5 hub and serial presence detect driver 20.Sh SYNOPSIS 21.Pa /dev/eeprom/spd511x/*/eeprom 22.Pp 23.Pa /dev/sensors/temperature/i2c/spd511x* 24.Sh DESCRIPTION 25The 26.Nm 27driver supports I2C devices compliant with JEDEC Standard JESD300-5 28which covers the hub and serial presence detect data found on DDR5 29DIMMs. 30The driver provides access to the hub's built-in temperature sensor 31through the 32.Xr ksensor 4D 33driver and provides read-only access to the SPD 34.Pq serial presence detect 35EEPROM through a character device powered by the 36.Xr eedev 4D 37driver. 38These devices are generally found at 7-bit addresses between 0x50 and 390x57. 40The lower three bits of the address are used to indicate which DIMM the 41device is found on 42.Pq ranging from 0 to 7 . 43.Pp 44The SPD device contains 1024 bytes of memory that are organized into 16 45blocks of 64 bytes each. 46A paging mechanism provides access to 128 bytes at a time. 47Devices can be found under 48.Pa /dev/eeprom/spd511x . 49Contents of the SPD data can be decoded with 50.Xr libjedec 3LIB . 51.Pp 52The temperature sensor measures in units of 0.25 degrees Celsius and its 53accuracy varies depending on the current temperature range. 54Temperature information is available to the system through the fault 55ma management architecture 56.Pq FMA . 57The file system location and programming interface to the 58.Nm 59temperature sensors are considered 60.Sy volatile . 61.Sh FILES 62.Bl -tag -width Pa 63.It Pa /dev/eeprom/spd511x/*/eeprom 64EEPROM character device file. 65.It Pa /dev/sensors/temperature/i2c/spd511x* 66Hub temperature sensor. 67.It Pa /kernel/drv/amd64/spd511x 68Device driver (x86) 69.El 70.Sh SEE ALSO 71.Xr libjedec 3LIB , 72.Xr ee100x 4D , 73.Xr eedev 4D , 74.Xr ts511x 4D , 75.Xr i2cadm 8 76.Rs 77.%Q JEDEC Solid State Technology Association 78.%T SPD5118 Hub and Serial Presence Detect Device Standard 79.%N JESD300-5B.01 Version 1.5.1 80.%D May 2024 81.Re 82