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gerrit.openbmc.org / openbmc / phosphor-gpio-monitor / ba917cf7cf4163f6a71d8f67609237f013149743
commitba917cf7cf4163f6a71d8f67609237f013149743[log] [tgz]
authorAmithash Prasad <amithash@meta.com>Mon Apr 21 14:52:43 2025 -0700
committerAmithash Prasad <amithash@meta.com>Wed Jun 18 09:20:12 2025 -0700
tree87b6476e736537933f466523619b32336e0aa06e
parent6dd97c4f1b1ff14f58e48415dc7ee73630d9addd [diff]
Add capability of handling GPIO initial values

The edge handling currently allows us to monitor
changes after the service has started. But, a GPIO
could have changed state when the BMC/service is
down and thus potentially missing an error condition.

To address this, two additional keys "INIT_HIGH" and
"INIT_LOW" are added. which will be called at start-up
depending on the current GPIO value.

Tested: Tested on QEMU with a test configuration
and ensured that the systemd units are called
correctly.

Change-Id: I8a6c969b9609080cf0846611831206376fd96c7d
Signed-off-by: Amithash Prasad <amithash@meta.com>
3 files changed
tree: 87b6476e736537933f466523619b32336e0aa06e
  1. multi-presence/
  2. presence/
  3. subprojects/
  4. test/
  5. .clang-format
  6. .gitignore
  7. 99-gpio-keys.rules
  8. evdev.cpp
  9. evdev.hpp
  10. file.hpp
  11. gpioMon.cpp
  12. gpioMon.hpp
  13. gpioMonMain.cpp
  14. LICENSE
  15. mainapp.cpp
  16. meson.build
  17. meson.options
  18. monitor.cpp
  19. monitor.hpp
  20. OWNERS
  21. phosphor-gpio-monitor@.service
  22. phosphor-gpio-presence@.service
  23. phosphor-multi-gpio-monitor.json
  24. phosphor-multi-gpio-monitor.service
  25. phosphor-multi-gpio-presence.json
  26. phosphor-multi-gpio-presence.service
  27. README.md
README.md

GPIO Monitoring

Implemented Daemons

phosphor-gpio-monitor

This daemon accepts a command line parameter for monitoring single gpio line and take action if requested. This implementation uses GPIO keys and only supports monitoring single GPIO line, for multiple lines, user has to run this daemon seperately for each gpio line.

phosphor-multi-gpio-monitor

This daemon accepts command line parameter as a well-defined GPIO configuration file in json format to monitor list of gpios from config file and take action defined in config based on gpio state change. It uses libgpiod library.

Difference

New implementation (phosphor-multi-gpio-monitor) provides multiple gpio line monitoring in single instance of phosphor-multi-gpio-monitor running. It is very easy to add list of gpios into JSON config file and it also supports of GPIO line by name defined in kernel.

Configuration

There is a phosphor-multi-gpio-monitor.json file that defines details of GPIOs which is required to be monitored. This file can be replaced with a platform specific configuration file via bbappend.

Following are fields in json file

  1. Name: Name of gpio for reference.
  2. LineName: this is the line name defined in device tree for specific gpio
  3. GpioNum: GPIO offset, this field is optional if LineName is defined.
  4. ChipId: This is device name either offset ("0") or complete gpio device ("gpiochip0"). This field is not required if LineName is defined.
  5. EventMon: Event of gpio to be monitored. This can be "FALLING", "RISING" OR "BOTH". Default value for this is "BOTH".
  6. Target: This is an optional systemd service which will get started after triggering event. A journal entry will be added for every event occurs irrespective of this definition.
  7. Targets: This is an optional systemd service which will get started after triggering corresponding event(RISING or FALLING). A journal entry will be added for every event occurs irrespective of this definition. Upon start up, depending on the current GPIO value, the systemd services for INIT_HIGH and INIT_LOW will be called (if defined).
  8. Continue: This is a optional flag and if it is defined as true then this gpio will be monitored continuously. If not defined then monitoring of this gpio will stop after first event.

Sample config file

[
  {
    "Name": "PowerButton",
    "LineName": "POWER_BUTTON",
    "GpioNum": 34,
    "ChipId": "gpiochip0",
    "EventMon": "FALLING",
    "Target": "PowerButtonDown.service",
    "Continue": true
  },
  {
    "Name": "PowerGood",
    "LineName": "PS_PWROK",
    "EventMon": "BOTH",
    "Targets": {
      "FALLING": ["PowerGoodFalling.service", "PowerOff.service"],
      "RISING": ["PowerGoodRising.service", "PowerOn.service"]
    },
    "Continue": false
  },
  { "Name": "SystemReset", "GpioNum": 46, "ChipId": "0" }
]

phosphor-multi-gpio-presence

This daemon accepts command line parameter as a well-defined GPIO configuration file in json format to monitor list of gpios from config file and sets inventory presence as defined in config based on gpio state change. It uses libgpiod library.

Difference

New implementation (phosphor-multi-gpio-presence) provides multiple gpio line monitoring in single instance of phosphor-multi-gpio-presence running. It is very easy to add list of gpios into JSON config file and it also supports of GPIO line by name defined in kernel.

Configuration

There is a phosphor-multi-gpio-presence.json file that defines details of GPIOs which is required to be monitored. This file can be replaced with a platform specific configuration file via bbappend.

Following are fields in json file

  1. Name: PrettyName of inventory item
  2. LineName: this is the line name defined in device tree for specific gpio
  3. GpioNum: GPIO offset, this field is optional if LineName is defined.
  4. ChipId: This is device name either offset ("0") or complete gpio device ("gpiochip0"). This field is not required if LineName is defined.
  5. Inventory: Object path under inventory that will be created
  6. ExtraInterfaces: [Optional] List of interfaces to associate to inventory item
  7. ActiveLow: [Optional] Object is present on LOW level
  8. Bias: [Optional] Configure a BIAS on the GPIO line, for example PULL_UP

Sample config file

[
  {
    "Name": "DIMM A0",
    "LineName": "POWER_BUTTON",
    "Inventory": "/system/chassis/motherboard/dimm_a0"
  },
  {
    "Name": "Powersupply 0",
    "ChipId": "0",
    "GpioNum": 14,
    "Inventory": "/system/chassis/motherboard/powersupply0",
    "ActiveLow": true,
    "Bias": "PULL_UP",
    "ExtraInterfaces": ["xyz.openbmc_project.Inventory.Item.PowerSupply"]
  }
]