docs/designs/multihost-phosphor-buttons.md

1 # Multi-host front panel phosphor buttons interface
12 Phosphor buttons module has currently option to monitor gpio events of power and
13 reset buttons and trigger power event handlers.
15 phosphor-buttons currently only support push type buttons.support for different
20 Currently handler events are only based on monitoring gpio events as input
21 (power and reset).There may be cases where we need to create button interface
22 which monitors non gpio events and triggers button actions for example events
29 available in the front panel apart from existing power and reset button
34 The front panel of bmc has buttons like power button, reset button in general
38    +----------------------------------------------+
42    |   +--------------+      +--------------+     |
44    |   | power button |      | reset button |     |
46    |   +--------------+      +--------------+     |
51    +----------------------------------------------+
57 example for a multihost platform yosemite-V2 it has host selector switch mux as
61 +---------------------------+                                      +------------+
63 |       yv2 front panel     |           power/           ---------+|  host 1    |
64 |                           |           reset/serial mux |         |            |
65 |     +----------------+    |           control          |         +------------+
67 |     |  power button  |-+  |                            |         +------------+
69 |     +----------------+ |  |                            |--------+|  host 2    |
71 |                        |  |                            |         +------------+
72 |                        |  |     +---------------+      |
73 |     +----------------+ |  |     |    host       |      |         +-------------+
74 |     |                | |  |     |  selector     |------+         |             |
75 |     |  reset button  --|--------+   switch      |      |---------+  host 3     |
76 |     |                |    |     +---------------+      |         |             |
77 |     +----------------+    |                            |         +-------------+
79 |                           |                            |          +------------+
81 |     +----------------+    |                            |----------+ host 4     |
82 |     | serial console +---------------------------------|          |            |
83 |     |    mux switch  |    |                            |          +------------+
85 |     +----------------+    |                            |           +-----------+
86 |                           |                            +-----------|   BMC     |
88 +---------------------------+                                        +-----------+
97 This host selector switch/selector switch has 4 gpio connected as input and
98 based on the gpio state values the host selector switch value is derived. The
99 possible switch values can vary from 0 to 10. The specific mapping between gpio
100 values and host selector values can be stored as part of gpio json config.
102 yosemiteV2 platform has 1 bmc and 4 hosts and only one power button and reset
109 This option is to use same power button and reset button for multiple hosts.
111 The power/reset button press events are triggered based on the value of host
116 host selector position value = 0,bmc is mapped to power and reset buttons host
117 selector position value = 1,host 1 is mapped to power and reset buttons host
118 selector position value = 2,host 2 is mapped to power and reset buttons host
119 selector position value = 3,host 3 is mapped to power and reset buttons host
120 selector position value = 4,host 4 is mapped to power and reset buttons
137 This is a extension which has three buttons : 1.Power button 2.reset button
140 Power and reset buttons are mapped to the same gpio of frontpanel so no separate
145 (push button) has different gpio lines than that of front panel host selector
148 host selector switch value is more than MaxPosition then it should be reset to
156    gpio event and process with single event handler.
164 - init() - This method may have gpio configuration and event handler
167 - handleEvent() - This method may have custom event handling routines for the
174 button interface monitors these 4 gpio io events as sd-event based event loop
175 and a single event handler function is called for all 4 gpio events.
177 Based on the 4 gpio state values, the host selector switch position value is
182 1. Position(property) - This is the property which holds the current value of
183    the host selector switch based on the GPIO state.
185 2. MaxPosition(property) - This is the property which keeps the maximum number
193 This button interface monitors the corresponding gpio lines for debug card host
194 selection button press and release event via sd-event based loop.
198 1. Released(signal) - This is signal is triggered in the ocp debug card event
206 This way when power and reset button press events are handled, the Host selector
214 console is selected.mux value can be set as configuring 4 gpio lines dedicated
219 0 - bmc serial console 1 - host 1 serial console 2 - host 2 serial console 3 -
220 host 3 serial console 4 - host 4 serial console
222 ### Change in power button and reset button interface event handler
224 If selector button instance is available,then the power button and reset button
229 The change impacts are under phosphor buttons repo,the existing power and reset