greenpak4: Fixed Greenpak4SystemReset to accurately reflect behavior described in latest (r085) datasheet.

azonenberg · azonenberg · commit 2b3ea0506472 · 2016-10-16T23:10:46.000-07:00
diff --git a/doc/gp4-hdl.tex b/doc/gp4-hdl.tex
@@ -3015,9 +3015,8 @@ \subsubsection{Introduction}
 device datasheet for exact functionality) and is independent of the power-on reset, which cannot be configured.
 
 Note that this block has slightly different timing than the power-on reset, which may cause glitches in some designs.
-To ensure consistent behavior between the runtime reset and boot, it may be necessary to instantiate the \tokenref{GP\_POR}{gp-por} block and gate glitching signals with \tokenstyle{RST\_DONE}.
-
-TODO: Latest GP4 datasheet (r085 p 20) seems to indicate FALLING mode does not exist, need to redo this?
+To ensure consistent behavior between the runtime reset and boot, it may be necessary to instantiate the
+\tokenref{GP\_POR}{gp-por} block and gate glitching signals with \tokenstyle{RST\_DONE}.
 
 \subsubsection{Port Descriptions}
 
@@ -3036,9 +3035,11 @@ \subsubsection{Parameter Descriptions}
 \whenstyle{Parameter} & \whenstyle{Type} & \whenstyle{Width} & \whenstyle{Function} \\
 \thickhline
 \tokenstyle{RESET\_MODE} & String & 1 &
-	\strexamplestyle{RISING} One-shot reset on rising edge of RST. \newline
-	\strexamplestyle{FALLING} One-shot reset on falling edge of RST. \newline
+	\strexamplestyle{EDGE} One-shot reset on rising edge of RST. \newline
 	\strexamplestyle{LEVEL} System is held in reset while RST is high.\\
+\tokenstyle{EDGE\_SPEED} & Integer & 9 &
+	Delay speed for the edge detector, in $\mu s$. Must be 4 or 500. \newline
+	Ignored if RESET\_MODE is LEVEL.\\
 \thinhline
 \end{tabularx}
 
@@ -3049,7 +3050,8 @@ \subsubsection{Verilog Usage Example}
 \begin{figure}[h]
 \begin{lstlisting}
 GP_SYSRESET #(
-	.RESET_MODE("LEVEL")
+	.RESET_MODE("LEVEL"),
+	.EDGE_SPEED(4)
 ) reset_ctrl (
 	.RST(rst)
 );
diff --git a/src/greenpak4/Greenpak4SystemReset.cpp b/src/greenpak4/Greenpak4SystemReset.cpp
@@ -31,6 +31,7 @@ Greenpak4SystemReset::Greenpak4SystemReset(
 	unsigned int cbase)
 	: Greenpak4BitstreamEntity(device, matrix, ibase, oword, cbase)
 	, m_resetMode(RISING_EDGE)
+	, m_resetDelay(500)
 	, m_reset(device->GetGround())
 {
 
@@ -93,20 +94,32 @@ void Greenpak4SystemReset::CommitChanges()
 		string p = ncell->m_parameters["RESET_MODE"];
 		if(p == "RISING")
 			mode = Greenpak4SystemReset::RISING_EDGE;
-		else if(p == "FALLING")
-			mode = Greenpak4SystemReset::FALLING_EDGE;
 		else if(p == "LEVEL")
 			mode = Greenpak4SystemReset::HIGH_LEVEL;
 		else
 		{
 			LogError(
-				"Reset \"%s\" has illegal reset mode \"%s\" (must be RISING, FALLING, or LEVEL)\n",
+				"Reset \"%s\" has illegal reset mode \"%s\" (must be RISING or LEVEL)\n",
 				ncell->m_name.c_str(),
 				p.c_str());
 			exit(-1);
 		}
 		SetResetMode(mode);
 	}
+
+	if(ncell->HasParameter("EDGE_SPEED"))
+	{
+		m_resetDelay = atoi(ncell->m_parameters["EDGE_SPEED"].c_str());
+
+		if( (m_resetDelay != 4) && (m_resetDelay != 500) )
+		{
+			LogError(
+				"Reset \"%s\" has illegal reset speed %d us (must be 4 or 500)\n",
+				ncell->m_name.c_str(),
+				m_resetDelay);
+			exit(-1);
+		}
+	}
 }
 
 bool Greenpak4SystemReset::Load(bool* /*bitstream*/)
@@ -128,23 +141,10 @@ bool Greenpak4SystemReset::Save(bool* bitstream)
 	// Configuration
 
 	//Reset mode
-	switch(m_resetMode)
-	{
-		case HIGH_LEVEL:
-			bitstream[m_configBase + 0] = true;
-			bitstream[m_configBase + 1] = false;
-			break;
-
-		case RISING_EDGE:
-			bitstream[m_configBase + 0] = false;
-			bitstream[m_configBase + 1] = false;
-			break;
-
-		case FALLING_EDGE:
-			bitstream[m_configBase + 0] = false;
-			bitstream[m_configBase + 1] = true;
-			break;
-	}
+	bitstream[m_configBase + 0] = (m_resetMode == HIGH_LEVEL);
+
+	//Edge detector speed
+	bitstream[m_configBase + 1] = (m_resetDelay == 500);
 
 	//Reset enable if m_reset is not a power rail (ground)
 	if(!m_reset.IsPowerRail())
diff --git a/src/greenpak4/Greenpak4SystemReset.h b/src/greenpak4/Greenpak4SystemReset.h
@@ -44,7 +44,6 @@ class Greenpak4SystemReset : public Greenpak4BitstreamEntity
 	enum ResetMode
 	{
 		RISING_EDGE,
-		FALLING_EDGE,
 		HIGH_LEVEL
 	};
 
@@ -64,6 +63,9 @@ class Greenpak4SystemReset : public Greenpak4BitstreamEntity
 	///Configuration for the reset
 	ResetMode m_resetMode;
 
+	///Delay value for the reset's edge detector
+	int m_resetDelay;
+
 	///The reset signal itself
 	Greenpak4EntityOutput m_reset;
 };
