PlatformManager Device Map (/run/devmap)

PlatformManager creates symbolic links under /run/devmap/ to provide stable, human-readable paths to platform devices. These symlinks should be used instead of raw device paths like /dev/i2c-5.

Directory Structure

/run/devmap/
├── i2c-busses/
│   ├── OPTICS_1 -> /dev/i2c-5
│   ├── OPTICS_2 -> /dev/i2c-6
│   └── SMB_SENSOR_BUS -> /dev/i2c-12
├── gpiochips/
│   ├── SCM_CPLD_GPIO -> /sys/class/gpio/gpiochip432
│   └── SMB_FPGA_GPIO -> /sys/class/gpio/gpiochip400
├── sensors/
│   ├── SCM_INLET_TEMP -> /sys/bus/i2c/devices/5-0048/hwmon/hwmon3
│   └── SMB_OUTLET_TEMP -> /sys/bus/i2c/devices/12-0049/hwmon/hwmon5
├── eeproms/
│   ├── CHASSIS_EEPROM -> /sys/bus/i2c/devices/2-0050/eeprom
│   └── SCM_EEPROM -> /sys/bus/i2c/devices/5-0051/eeprom
├── watchdogs/
│   └── FAN_WATCHDOG -> /dev/watchdog0
├── fpgas/
│   └── IOB_FPGA -> /sys/bus/pci/devices/0000:07:00.0
├── cplds/
│   └── SCM_CPLD -> /sys/bus/i2c/devices/5-0035
├── spi-devices/
│   └── BIOS_SPI -> /dev/spidev0.0
├── mdio-busses/
│   └── RTM_MDIO_0 -> /sys/class/mdio_bus/mdio-0
├── xcvrs/
│   └── XCVR_1 -> /sys/bus/pci/devices/.../xcvr_ctrl.1
└── leds/
    └── PORT_1_LED_1 -> /sys/class/leds/port1:led1

Supported Device Groups

Group	Description	Example Target
i2c-busses	I2C bus character devices	/dev/i2c-N
gpiochips	GPIO controller sysfs paths	/sys/class/gpio/gpiochipN
sensors	Hardware monitoring sensors	/sys/bus/i2c/devices/.../hwmon/hwmonN
eeproms	EEPROM sysfs paths	/sys/bus/i2c/devices/.../eeprom
watchdogs	Watchdog character devices	/dev/watchdogN
fpgas	FPGA PCI device sysfs paths	/sys/bus/pci/devices/...
cplds	CPLD I2C device sysfs paths	/sys/bus/i2c/devices/...
spi-devices	SPI character devices	/dev/spidevN.M
mdio-busses	MDIO bus sysfs paths	/sys/class/mdio_bus/mdio-N
xcvrs	Transceiver controller paths	Vendor-specific
leds	LED class device paths	/sys/class/leds/...

Configuration

Symlinks are configured in the platform configuration using symbolicLinkToDevicePath:

{
  "symbolicLinkToDevicePath": {
    "/run/devmap/eeproms/CHASSIS_EEPROM": "/[CHASSIS_EEPROM]",
    "/run/devmap/sensors/SMB_INLET_SENSOR": "/SMB_SLOT@0/[INLET_SENSOR]",
    "/run/devmap/sensors/FAN_CTRL": "/SMB_SLOT@0/[FAN_CTRL]"
  }
}

Naming Conventions

Symlink names should:

• Use UPPER_CASE with underscores
• Be descriptive of the device function
• Include numeric suffixes for multiple instances (e.g., OPTICS_1, OPTICS_2)