control:docs: Create fans.md
This describes the fans.json file.
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: Idd206d02d869d5eb35e4ad6b89191bef7452310c
diff --git a/docs/control/fans.md b/docs/control/fans.md
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+# fans.json
+
+## JSON Example
+
+```
+[
+ {
+ "name": "fan0",
+ "zone": "0",
+ "sensors": ["fan0_0"],
+ "target_interface": "xyz.openbmc_project.Control.FanSpeed"
+ }
+ ...
+]
+```
+
+## Attributes
+
+### name
+The D-Bus name of the fan FRU. Required.
+
+### zone
+The zone the fan is in. Required.
+
+### sensors
+The D-bus sensor names associated with that fan. Required.
+
+### target_interface
+The D-Bus interface to use for setting the fan target speed/PWM. Either
+`xyz.openbmc_project.Control.FanSpeed` for RPM controlled fans or
+`xyz.openbmc_project.Control.FanPWM` for PWM controlled fans. Required.