tweak gpmc timing

1 files changed, 40 insertions, 17 deletions

diff --git a/bus.c b/bus.c
index a860893..db24a2e 100644
--- a/bus.c
+++ b/bus.c
@@ -151,15 +151,6 @@ static void gpmc_printinfo()
 
 }
 
-// The shift amounts
-
-#define CSWROFFTIME 16
-#define CSRDOFFTIME 8
-#define OEOFFTIME 8
-#define RDACCESSTIME 16
-#define WRCYCLETIME 8
-#define RDCYCLETIME 0
-#define WRACCESSTIME 24
 
 #define BIDIR 0x20
 #define PULL_UP 0x10
@@ -175,9 +166,42 @@ static void gpmc_printinfo()
 #define MODE_7 0x07
 
 
-static void gpmc_setup(int chipselect, int accesscycles, int size, bool enablecs, int baseaddress)
-{
+// multiply by 10 ns
+#define TOTAL_IO_CYCLE 20;  // 200 ns cycle
+#define CS_DELAY 0;         // CS low right away
+#define DELAY_TO_WR_RD 4;   // i.e., 40 ns after CS
+#define WR_RD_WIDTH 15;     // 40 ns delay + 150 ns pulse + 10 ns spare
+#define DATA_READY 15;      // data ready 150 ns after CS, 110 ns after RD/WR
 
+
+static void gpmc_setup(void)
+{
+	int chipselect = 0;
+	int size = GPMC_SIZE_16MB;
+	bool enablecs = true;
+	int baseaddress = 1;
+
+
+	int CSWROFFTIME = TOTAL_IO_CYCLE - CS_DELAY;
+	int CSRDOFFTIME = TOTAL_IO_CYCLE - CS_DELAY;
+	int CSONTIME = CS_DELAY;
+	int config2 = (CSWROFFTIME << 16) | (CSRDOFFTIME << 8) | CSONTIME;
+
+	int WEOFFTIME = DELAY_TO_WR_RD + WR_RD_WIDTH;
+	int WEONTIME = DELAY_TO_WR_RD;
+	int OEOFFTIME = DELAY_TO_WR_RD + WR_RD_WIDTH;
+	int OEONTIME = DELAY_TO_WR_RD;
+	int config4 = (WEOFFTIME << 24) | (WEONTIME << 16) | (OEOFFTIME << 8) | OEONTIME;
+
+	int RDACCESSTIME = DATA_READY;
+	int WRCYCLETIME = TOTAL_IO_CYCLE;
+	int RDCYCLETIME = TOTAL_IO_CYCLE;
+	int config5 = (RDACCESSTIME << 16) | (WRCYCLETIME << 8) | RDCYCLETIME;
+
+	int WRACCESSTIME = DATA_READY;
+	int config6 = WRACCESSTIME << 24;
+	
+	
 	pinmux_configurepin("gpmc_csn0", 	PULL_UP | MODE_0);
 	pinmux_configurepin("gpmc_oen_ren", 	PULL_UP | MODE_0);
 	pinmux_configurepin("gpmc_wen", 	PULL_UP | MODE_0);
@@ -209,12 +233,11 @@ static void gpmc_setup(int chipselect, int accesscycles, int size, bool enablecs
 		*(registers + displacement + GPMC_CONFIG7) = 0x0;
 
 		*(registers + displacement + GPMC_CONFIG1) = 0x0;
-		*(registers + displacement + GPMC_CONFIG2) = (accesscycles << CSWROFFTIME) | (accesscycles << CSRDOFFTIME);
+		*(registers + displacement + GPMC_CONFIG2) = config2;
 		*(registers + displacement + GPMC_CONFIG3) = 0x0; // not using ADV so we can ignore this guy
-		*(registers + displacement + GPMC_CONFIG4) = (accesscycles << OEOFFTIME);
-		*(registers + displacement + GPMC_CONFIG5) = (accesscycles << RDACCESSTIME) | (accesscycles << WRCYCLETIME)
-		                | (accesscycles << RDCYCLETIME);
-		*(registers + displacement + GPMC_CONFIG6) = (accesscycles << WRACCESSTIME);
+		*(registers + displacement + GPMC_CONFIG4) = config4;
+		*(registers + displacement + GPMC_CONFIG5) = config5;
+		*(registers + displacement + GPMC_CONFIG6) = config6;
 		*(registers + displacement + GPMC_CONFIG7) = size << 8 | (enablecs ? 1 << 6 : 0) | baseaddress;
 
 		gpmc_unmapregisters();
@@ -343,7 +366,7 @@ void bus_init()
 	}
 
 	if (isbb) {
-		gpmc_setup(0, GPMCACCESSTIME, GPMC_SIZE_16MB, true, 1);
+		gpmc_setup();
 
 		extbus = (uint8_t*) util_mapmemoryblock(0x01000000, 0x100);