set fixed frequency and print warning if a different frequency is requested

git-svn-id: https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk@1353 b68d4a1b-bc3d-0410-92ed-d4ac073336b7

jtag/ChangeLog

@@ -1,5 +1,8 @@
 2008-09-06  Arnim Laeuger  <arniml@users.sourceforge.net>
 
+   * src/tap/cable/usbblaster.c: set fixed frequency and print warning
+     if a different frequency is requested
+
    * src/tap/cable/generic.c: fixed calibration loop
 
    * src/svf/svf.c: require frequency setting from cable for

jtag/src/tap/cable/usbblaster.c

@@ -50,6 +50,8 @@
 
 #define TDO    0
 
+#define FIXED_FREQUENCY 12000000L
+
 /* The default driver if not specified otherwise during connect */
 #ifdef ENABLE_LOWLEVEL_FTD2XX
 #define DEFAULT_DRIVER "ftd2xx"
@@ -93,6 +95,16 @@ usbblaster_connect( char *params[], cable_t *cable )
 	return 0;
 }
 
+void
+usbblaster_set_frequency( cable_t *cable, uint32_t new_frequency )
+{
+	if (new_frequency != FIXED_FREQUENCY)
+		printf( _("Warning: USB-Blaster frequency is fixed to %ld Hz\n"),
+		        FIXED_FREQUENCY );
+
+	cable->frequency = FIXED_FREQUENCY;
+}
+
 static int
 usbblaster_init( cable_t *cable )
 {
@@ -108,6 +120,8 @@ usbblaster_init( cable_t *cable )
 
 	cx_xfer( cmd_root, NULL, cable, COMPLETELY );
 
+	usbblaster_set_frequency( cable, FIXED_FREQUENCY );
+
 	return 0;
 }
 
@@ -421,12 +435,6 @@ usbblaster_flush( cable_t *cable, cable_flush_amount_t how_much )
 	}
 }
 
-void
-usbblaster_set_frequency( cable_t *cable, uint32_t new_frequency )
-{
-	cable->frequency = new_frequency;
-}
-
 void
 usbblaster_help( const char *cablename )
 {