Support to accumulate PWM of different controllers for same sensor

Description:
1. Add one property: accumulateSetPoint in zone of fan table that could
   be used to enable accumulation of output PWM of different controllers
   with same sensor.

2. Add one property: checkHysterWithSetpt in pid info of fan table to
   select to compare current input and setpoint to check hysteresis.

3. The purpose of accumulate the stepwise output and PID output for
   one sensor is that the setting of stepwise could use to prevent
   the fan speed from suddenly increasing from a very low speed to a
   very high speed due to reaching the setpoint.

   Use stepwise before setpoint could also keep the PWM steady at
   low ambient temperature.

Design:
1. Search "accumulateSetPoint" field in fan table.
   If the value was true, accumulate the output PWM of different
   controllers with same profile name.

2. Support two method to calculate PID output that could be chosen by
   setting the "checkHysterWithSetpt" to true in pid info of fan table.

   If the flag was set to true, it won't calculate PWM output if the
   input lower than setpoint.

Test Case:
1. Check the output PWM of different controllers with same profile
   name could be accumulated - pass.

2. Set "checkHysterWithSetpt" to true and check PID output would not be
   calculated if the input temperature was lower than setpoint - pass.

Please see more details in gist:
https://gist.github.com/DelphineCCChiu/a6170d3e1a12fc4ee76fad324382fba3

Change-Id: I9f38f250d72545784c6c11be2fde7d45f0b385c4
Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>
diff --git a/pid/ec/pid.hpp b/pid/ec/pid.hpp
index 9dac6a4..9db08fd 100644
--- a/pid/ec/pid.hpp
+++ b/pid/ec/pid.hpp
@@ -19,21 +19,23 @@
  */
 typedef struct
 {
-    bool initialized;         // has pid been initialized
+    bool initialized;          // has pid been initialized
+    bool checkHysterWithSetpt; // compare current input and setpoint to check
+                               // hysteresis
 
-    double ts;                // sample time in seconds
-    double integral;          // integral of error
-    double lastOutput;        // value of last output
-    double lastError;         // value of last error
+    double ts;                 // sample time in seconds
+    double integral;           // integral of error
+    double lastOutput;         // value of last output
+    double lastError;          // value of last error
 
-    double proportionalCoeff; // coeff for P
-    double integralCoeff;     // coeff for I
-    double derivativeCoeff;   // coeff for D
-    double feedFwdOffset;     // offset coeff for feed-forward term
-    double feedFwdGain;       // gain for feed-forward term
+    double proportionalCoeff;  // coeff for P
+    double integralCoeff;      // coeff for I
+    double derivativeCoeff;    // coeff for D
+    double feedFwdOffset;      // offset coeff for feed-forward term
+    double feedFwdGain;        // gain for feed-forward term
 
-    limits_t integralLimit;   // clamp of integral
-    limits_t outLim;          // clamp of output
+    limits_t integralLimit;    // clamp of integral
+    limits_t outLim;           // clamp of output
     double slewNeg;
     double slewPos;
     double positiveHysteresis;
@@ -46,6 +48,9 @@
 /* Condensed version for use by the configuration. */
 struct pidinfo
 {
+    bool checkHysterWithSetpt;  // compare current input and setpoint to check
+                                // hysteresis
+
     double ts;                  // sample time in seconds
     double proportionalCoeff;   // coeff for P
     double integralCoeff;       // coeff for I