readback on write disable option

Registers sometimes have read side-effects.
Provide an option to disable readback on write.

Readback on write can be disabled with '-r 0' on command line
or 'readback = 0' from memedit prompt.

Signed-off-by: Jon Ringle <jon@ringle.org>

Removed some braces and added some help text.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

4 files changed, 26 insertions, 8 deletions

diff --git a/memedit.1 b/memedit.1
index 5063a73..4e8429e 100644
--- a/memedit.1
+++ b/memedit.1
@@ -35,6 +35,9 @@ the line is treated as a comment. E.g.:
 SR0 = 0x0   # Some Control / Status Register
 .br 
 .br
+.TP
+\fB\-\-readback | \-r\fR
+readback on write (default on)
 .TP 
 \fB\-\-help | \-h\fR
 Output help information and exit.
diff --git a/memedit.c b/memedit.c
index 8389302..062355a 100644
--- a/memedit.c
+++ b/memedit.c
@@ -20,6 +20,7 @@ extern int yyparse();
     
 
 int debug = 0;
+int readback = 1;
 int mmaped_access = 0;
 FILE *rl_instream;
 int fd = -1;
@@ -51,7 +52,8 @@ int main (int argc, char *argv[])
 		return EXIT_FAILURE;
 	}
 	
-	debug = kom_arg->V; 
+	debug = kom_arg->V;
+	readback = !kom_arg->r;
 
 	if (kom_arg->s)
 	{
diff --git a/memedit.y b/memedit.y
index 61f242a..35d7850 100644
--- a/memedit.y
+++ b/memedit.y
@@ -14,7 +14,7 @@
 
 extern int errno;
 extern int fd;
-extern int debug, mmaped_access;
+extern int debug, mmaped_access, readback;
 extern void *mem;
 unsigned int cur_position;
 
@@ -209,7 +209,8 @@ mm:	MM { write_len = $1; if (debug > 3) printf ("write_len = %d\n", write_len);}
 
 exp:	num {
 		cur_position = $1;
-		printf ("new values:\n0x%08x: ",cur_position);
+		if (readback)
+			printf ("new values:\n0x%08x: ",cur_position);
 	}
 	| exp num {
 		unsigned int c = $2;
@@ -218,16 +219,19 @@ exp:	num {
 			case 1:
 				c &= 0xff;
 				*(volatile unsigned char *)(mem + cur_position) = c;
-				printf ("%02x ", *(volatile unsigned char *)(mem + cur_position));
+				if (readback)
+					printf ("%02x ", *(volatile unsigned char *)(mem + cur_position));
 				break;
 			case 2:
 				c &= 0xffff;
 				*(volatile unsigned short *)(mem + cur_position) = c;
-				printf ("%04x ", *(volatile unsigned short *)(mem + cur_position));
+				if (readback)
+					printf ("%04x ", *(volatile unsigned short *)(mem + cur_position));
 				break;
 			case 4:
 				*(volatile unsigned long *)(mem + cur_position) = c;
-				printf ("%08lx ", *(volatile unsigned long *)(mem + cur_position));
+				if (readback)
+					printf ("%08lx ", *(volatile unsigned long *)(mem + cur_position));
 				break;
 			}
 			cur_position += write_len;
@@ -263,6 +267,8 @@ void print_help (void) {
 	printf ("mm <offset> <val1> .. <valN>	modify from value <offset>\n");
 	printf ("mf <start> <length> <value>	fill from <offset> for <length> with <value>\n");
 	printf ("env				print all currently defined variables\n");
+	printf ("readback <val>			if true (default), read back values after write operation\n");
+	printf ("				disable to avoid side-effects (e.g. for irq-registers)\n");
 	printf ("<var> = <expr>			set variable <var> to <expr>\n");
 	printf ("<var>				print variable <var>\n");
 	printf ("\n");
@@ -281,7 +287,13 @@ void print_help (void) {
 
 void set_variable (char *param, int val) {
 	variable *l, *tmp;
-		
+
+	if (strncmp (param, "readback", 8) == 0) {
+		readback = val;
+		printf ("readback = %d\n", readback);
+		return;
+	}
+
 	if (strncmp (param, "debug", 5) == 0) {
 		debug = val; 
 		printf ("debug = %d\n", debug);
diff --git a/memedit_parser.gp b/memedit_parser.gp
index 3eb75c3..5402503 100644
--- a/memedit_parser.gp
+++ b/memedit_parser.gp
@@ -1,4 +1,5 @@
 /* memedit_parser.gp */
-#mandatory memedit
+#mandatory file
 V / verbose int 0 		"verbose output"
 s / startfile string ""		"execute startup file"
+r / readback flag 1		"readback on write (default on)"