Author: Velumani T(velu), velumanit@hcl Naveen Moses S(naveen.moses), naveen.mosess@hcl.com
Other contributors:
Created: August 3, 2021
Phosphor buttons module has currently option to monitor gpio events of power and reset buttons and trigger power event handlers.
phosphor-buttons currently only support push type buttons.support for different form factor inputs such as switches/MUX other than push type buttons are needed for some hardwares. It will be helpful if we could add option to support additional input types in phosphor button interfaces and event handling.
Currently handler events are only based on monitoring gpio events as input (power and reset).There may be cases where we need to create button interface which monitors non gpio events and triggers button actions for example events based on dbus property changes.
This feature is needed to support additional phosphor button interfaces corresponding to platform specific hardware buttons/MUX/Switches which are available in the front panel apart from existing power and reset button interfaces.
The front panel of bmc has buttons like power button, reset button in general the code for monitoring these buttons and triggering actions are supported.
+----------------------------------------------+ | | | Front panel | | | | +--------------+ +--------------+ | | | | | | | | | power button | | reset button | | | | | | | | | +--------------+ +--------------+ | | | | | | | | | +----------------------------------------------+
platform specific front panel may contain additional hardware buttons or mux switch
example for a multihost platform yosemite-V2 it has host selector switch mux as additional button in front panel.
+---------------------------+ +------------+ | | | | | yv2 front panel | power/ ---------+| host 1 | | | reset/serial mux | | | | +----------------+ | control | +------------+ | | | | | | | power button |-+ | | +------------+ | | | | | | | | | +----------------+ | | |--------+| host 2 | | | | | | | | | | | +------------+ | | | +---------------+ | | +----------------+ | | | host | | +-------------+ | | | | | | selector |------+ | | | | reset button --|--------+ switch | |---------+ host 3 | | | | | +---------------+ | | | | +----------------+ | | +-------------+ | | | | | | +------------+ | | | | | | +----------------+ | |----------+ host 4 | | | serial console +---------------------------------| | | | | mux switch | | | +------------+ | | | | | | +----------------+ | | +-----------+ | | +-----------| BMC | | | | | +---------------------------+ +-----------+
There are two additional hardware buttons/switch available in the frontpanel for yv2.
This host selector switch/selector switch has 4 gpio connected as input and based on the gpio state values the host selector switch value is derived. The possible switch values can vary from 0 to 10. The specific mapping between gpio values and host selector values can be stored as part of gpio json config.
yosemiteV2 platform has 1 bmc and 4 hosts and only one power button and reset button.
For example, when the power button is pressed, The value of the host selector switch position(1 to 10) decides whether the power button action is needs to be triggered for bmc or any one of the hosts.
This option is to use same power button and reset button for multiple hosts.
The power/reset button press events are triggered based on the value of host selector switch position.
host selector position value = 0,bmc is mapped to power and reset buttons host selector position value = 1,host 1 is mapped to power and reset buttons host selector position value = 2,host 2 is mapped to power and reset buttons host selector position value = 3,host 3 is mapped to power and reset buttons host selector position value = 4,host 4 is mapped to power and reset buttons
There is also uart console for each host and bmc which is connected via a MUX switch.
At a time any one of the device (either bmc or any one host) can be accessed via the console which is based on the UART MUX switch configuration.
Based on the position of the host selector switch, a separate handler interface can configure the respective serial console device is selected.
An OCP debug card can be connected to yosemitev2 via usb for debugging purpose.
This is a extension which has three buttons : 1.Power button 2.reset button 3.host selector button
Power and reset buttons are mapped to the same gpio of frontpanel so no separate event handling is required.
The host selector button purpose is same as that of the front panel host selector switch in yosemitev2 front panel. The debug card host selector button (push button) has different gpio lines than that of front panel host selector switch gpios. Whenever the debug host selector button is pressed the host selector switch position value should be increased up to MaxPosition. If the host selector switch value is more than MaxPosition then it should be reset to zero.
Three high level changes are required in the phosphor button interface class
Add support for adding button interfaces which are monitoring more than one gpio event and process with single event handler.
Add support to monitor button / switch interface event based on dbus property changes (needed for serial console MUX).
Each button interface class can be extended with the following overridable methods to allow platform specific logic if needed in a derived class.
init() - This method may have gpio configuration and event handler initialization.
handleEvent() - This method may have custom event handling routines for the respective button interface.This should be be called from the main even handler function.
The host selector switch has 4 gpios associated with it. host selector switch button interface monitors these 4 gpio io events as sd-event based event loop and a single event handler function is called for all 4 gpio events.
Based on the 4 gpio state values, the host selector switch position value is derived and stored as a dbus property with name "Position".
Position(property) - This is the property which holds the current value of the host selector switch based on the GPIO state.
MaxPosition(property) - This is the property which keeps the maximum number of Position the Position property can hold.(This value is based on the number of hosts available in the platform)
A separate interface for debug card host selector button is created.
This button interface monitors the corresponding gpio lines for debug card host selection button press and release event via sd-event based loop.
When the event handler is called once the button is released, then the host selector switch dbus property "Position" is increased by 1. The host selector switch dbus property value is rollover to zero after Position value exceeds MaxPosition Value.
This way when power and reset button press events are handled, the Host selector Position property is referred and based on the Position respective power events are called.
This button interface monitors for change in host selector switch Position dbus property and based on the dbus property value change, corresponding serial console is selected.mux value can be set as configuring 4 gpio lines dedicated for the serial console mux.
0 - bmc serial console 1 - host 1 serial console 2 - host 2 serial console 3 - host 3 serial console 4 - host 4 serial console
If selector button instance is available,then the power button and reset button pressed events must route to appropriate multihost dbus service name
The change impacts are under phosphor buttons repo,the existing power and reset button handlers are calling dbus calls for single host power events. This calls should be modified to adapt corresponding multi host power events and the respective host dbus object is based on host selector position.
The proposed design can be tested in a platform in which the multiple hosts are connected.