Document byte order of I2CInterface read/write

Update the doxygen comments for the following two I2CInterface methods:
* void read(uint8_t addr, uint16_t& data);
* void write(uint8_t addr, uint16_t data);

Document that the two bytes are transmitted with the low order byte
first.

The I2CInterface methods call the following two i2c-dev functions:
* i2c_smbus_read_word_data()
* i2c_smbus_write_word_data()

The SMBus Read Word and Write Word protocols require the low order byte
to be sent first.

Testing:
  * Tested on Witherspoon using i2cget and i2cset.  These command line
    tools call the same two i2c-dev functions.  Verified that the low
    order byte is read/written first.

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I83ba69f8cde08ee719d34802afed691a61fe3e84
1 file changed
tree: 5a7555744f28d95c2eafb674b7ecdb126ff0d5be
  1. cold-redundancy/
  2. example/
  3. org/
  4. phosphor-power-supply/
  5. phosphor-regulators/
  6. power-sequencer/
  7. power-supply/
  8. services/
  9. test/
  10. tools/
  11. .clang-format
  12. .gitignore
  13. argument.hpp
  14. device.hpp
  15. device_monitor.hpp
  16. elog-errors.hpp
  17. file.hpp
  18. gpio.cpp
  19. gpio.hpp
  20. LICENSE
  21. MAINTAINERS
  22. meson.build
  23. meson_options.txt
  24. names_values.hpp
  25. pmbus.cpp
  26. pmbus.hpp
  27. README.md
  28. types.hpp
  29. utility.cpp
  30. utility.hpp
README.md

Code for detecting and analyzing power faults on Witherspoon.

To Build

To build this package, do the following steps:

    1. meson build
    2. ninja -C build

To clean the repository again run `rm -rf build`.

Power Supply Monitor and Util JSON config

Several applications in this repository require a PSU JSON config to run. The JSON config file provides information for:

  • Where to access the pmbus attributes
  • Which attribute file in pmbus maps to which property and interface in D-Bus
  • Which kernel device directory is used on which PSU

There is an example psu.json to describe the necessary configurations.

  • inventoryPMBusAccessType defines the pmbus access type, which tells the service which sysfs type to use to read the attributes. The possible values are:
    • Base: The base dir, e.g. /sys/bus/i2c/devices/3-0069/
    • Hwmon: The hwmon dir, e.g. /sys/bus/i2c/devices/3-0069/hwmon/hwmonX/
    • Debug: The pmbus debug dir, e.g. /sys/kernel/debug/pmbus/hwmonX/
    • DeviceDebug: The device debug dir, e.g. '/sys/kernel/debug/./`
    • HwmonDeviceDebug: The hwmon device debug dir, e.g. /sys/kernel/debug/pmbus/hwmonX/cffps1/
  • fruConfigs defines the mapping between the attribute file and the FRU inventory interface and property. The configuration example below indicates that the service will read part_number attribute file from a directory specified by the above pmbus access type, and assign to PartNumber property in xyz.openbmc_project.Inventory.Decorator.Asset interface.
      "fruConfigs": [
        {
          "propertyName": "PartNumber",
          "fileName": "part_number",
          "interface": "xyz.openbmc_project.Inventory.Decorator.Asset"
        }
      ]
    
  • psuDevices defines the kernel device dir for each PSU in inventory. The configuration example below indicates that powersupply0's device is located in /sys/bus/i2c/devices/3-0069.
      "psuDevices": {
        "/xyz/openbmc_project/inventory/system/chassis/motherboard/powersupply0" : "/sys/bus/i2c/devices/3-0069",
      }