1# Sensor Config 2 3This program is only meant to control fans given thermal sensor readings. 4 5All sensors in phosphor-dbus-interfaces for OpenBMC use Sensor.Value as their 6accessor. This provides read-only access to information. The goal of the 7configuration is to specify how it can be read and if it's a fan, how the PID 8output can be written. Initially there'll only be sysfs and passive dbus 9access. If a writePath for a sensor is a dbus path, then the system will need 10to verify which Control.Fan* interfaces is registered and send values to the 11Target property of that interface. 12 13The min/max specified are to range a writePercent to the sensor. The current 14FanController object outputs the new fan speed goal as a PWM percentage. Other 15fan PID control objects may not, and they can leave the fields as 0 & 0. 16 17The only requirement for a sensor is that it isn't writeonly. Only fans are 18expected to have a writePath set, and in this current version non-fan sensors 19are assumed readonly. 20 21The sensor names are unique across all zones. 22 23"sensors" : [ 24 { 25 "name": "fan1", /* Name of the sensor. */ 26 "type": "fan", /* Type of sensor, fan, temp, margin */ 27 "readPath": "", /* How the sensor can be read[1] */ 28 "writePath": "", /* How the sensor can be set[2] */ 29 "min": 0, /* The minimum value used for scaling writes (int64) */ 30 "max": 255, /* The maximum value used for scaling writes (int64) */ 31 "timeout": 0 /* The timeout value for the sensor, used for failsafe, 0 32 * means no timeout (int64) */ 33 }, 34] 35 36[1] readPath has multiple options: 37* If it has "/xyz/openbmc_project/extsensors/" in it, it's an EXTERNAL or 38 host-provided sensor. 39* If it has "/xyz/openbmc_project/" in it, it's a sensor whose value is 40 received passively over dbus. 41* If it has "/sys/" in it, it's a sensor read directly from sysfs. 42 43[2] 44* This can be left blank if the sensor is read-only. 45* If it has "/sys/" in it, it's a sensor written to sysfs. 46 * If min and max are non-zero, it'll convert the value to within the range. 47 and output that modified value. So, if it receives a value of .90 and min 48 is 0, and max is 255, it'll convert that to a value of 229.5 that is then 49 cast to int64_t. 50 51# PID Config 52 53The PID configuration is a list of PIDs per zone. 54 55"zones" : [ 56 { 57 "id": 1, /* zone id. */ 58 "minThermalOutput": 3000.0, /* The minimum thermal RPM value. (double) */ 59 "failsafePercent": 75.0, /* The percent to use when the zone is in fail-safe mode. (double) */ 60 "pids": [ 61 { 62 "name": "fan1-5", /* PID name */ 63 "type": "fan", /* Type of PID, fan, temp, or margin. */ 64 "inputs": ["fan1", "fan5"], /* Sensor names that are inputs for the PID */ 65 "setpoint": 90.0, /* For temp/margin PIDs this is the setpoint, ignored otherwise (double) */ 66 "pid": { 67 "samplePeriod": 0.1, /* The input sample period. (double) */ 68 "proportionalCoeff": 0.0, /* The proportional coefficient. (double) */ 69 "integralCoeff": 0.0, /* The integral coefficient. (double) */ 70 "feedFwdOffsetCoeff": 0.0, /* The feed-forward offset coefficient. (double) */ 71 "feedFwdGainCoeff": 0.010, /* The feed-forward gain coefficient. (double) */ 72 "integralLimit_min": 0.0, /* The integral limit clamp, min, max (double) */ 73 "integralLimit_max": 0.0, 74 "outLim_min": 30.0, /* the PID output clamp, min, max (double) */ 75 "outLim_max": 100.0, 76 "slewNeg": 0.0, /* The slew negative value. (double) */ 77 "slewPos": 0.0 /* The slew positive value. (double) */ 78 } 79 } 80 ] 81 } 82] 83