docs/designs/device-tree-gpio-naming.md

1 # Device Tree GPIO Naming in OpenBMC
12 subsystem. The replacement is a "descriptor-based" character device interface.
25 specific field used to name the GPIOs in the DTS is `gpio-line-names`. This
29 scheme in the face of a universe of potential use-cases.
31 Scoping the problem down to just the vastness of OpenBMC narrows the
37 - Ensure common function GPIOs within OpenBMC use the same naming convention
43 (when available on an OpenBMC system). This naming convention must be followed
46 This list below includes all common GPIOs within OpenBMC. Any OpenBMC system
52 Pattern: `*-button`
55 BMC-less machines use a button to trigger system behavior and in a BMC-managed
59 #### power-button
68 - `host*-ready`: Host ready, active high
69 - `host*-ready-n`: Host ready, active low
73 - host0-ready
74 - host1-ready-n
75 - ...
79 Pattern: `led-*`
81 #### led-fault
83 #### led-identify
85 #### led-power
87 #### led-sys-boot-status
89 #### led-attention
91 #### led-hdd-fault
93 #### led-rear-fault
95 #### led-rear-power
97 #### led-rear-id
101 Pattern: `power-*`, `regulator-*`
103 #### power-chassis-control
105 Set to initiate power-on or power-off of the chassis.
107 #### power-chassis-good
111 #### power-config-full-load
122 #### power-ffs-sync-history
130 #### regulator-standby-faulted
134 non-faulted condition after AC power cycle when no standby power regulator fault
138 #### rtc-battery-voltage-read-enable
144 Pattern: `presence-*`
146 #### presence-ps0, presence-ps1, ..., presence-ps\<N>
156 Pattern: `reset-cause-*`
158 #### reset-cause-pinhole
168 #### bmc-secure-boot
170 Input pin that indicates that the BMC is configured to boot with security
174 security).
180 #### air-water
184 #### factory-reset-toggle
198 ##### cfam-reset
209 - Continue to hard code a config file per system type that has the gpio bank and
213 - Have the device tree GPIO names match the hardware schematics and then have
220 Need to ensure OpenBMC device trees conform to the above naming conventions.
228 [2]: https://www.kernel.org/doc/html/latest/driver-api/gpio/index.html
230   https://lore.kernel.org/linux-arm-kernel/20200306170218.79698-1-geissonator@yahoo.com/