powerpc/boot: Parse chosen/cmdline-timeout parameter

On some platforms a 5 second timeout during boot might be quite long, so
make it configurable. Run the loop at least once to let the user stop
the boot by holding a key pressed. If the timeout is set to 0, don't
wait for input, which can be used as a workaround if the boot hangs on
random data coming in on the serial port.
Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
[mpe: Changelog wording & whitespace]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/boot/main.c

@@ -144,13 +144,24 @@ static char cmdline[BOOT_COMMAND_LINE_SIZE]
 
 static void prep_cmdline(void *chosen)
 {
+	unsigned int getline_timeout = 5000;
+	int v;
+	int n;
+
+	/* Wait-for-input time */
+	n = getprop(chosen, "linux,cmdline-timeout", &v, sizeof(v));
+	if (n == sizeof(v))
+		getline_timeout = v;
+
 	if (cmdline[0] == '\0')
 		getprop(chosen, "bootargs", cmdline, BOOT_COMMAND_LINE_SIZE-1);
 
 	printf("\n\rLinux/PowerPC load: %s", cmdline);
+
 	/* If possible, edit the command line */
-	if (console_ops.edit_cmdline)
-		console_ops.edit_cmdline(cmdline, BOOT_COMMAND_LINE_SIZE);
+	if (console_ops.edit_cmdline && getline_timeout)
+		console_ops.edit_cmdline(cmdline, BOOT_COMMAND_LINE_SIZE, getline_timeout);
+
 	printf("\n\r");
 
 	/* Put the command line back into the devtree for the kernel */

arch/powerpc/boot/ops.h

@@ -58,7 +58,7 @@ extern struct dt_ops dt_ops;
 struct console_ops {
 	int	(*open)(void);
 	void	(*write)(const char *buf, int len);
-	void	(*edit_cmdline)(char *buf, int len);
+	void	(*edit_cmdline)(char *buf, int len, unsigned int getline_timeout);
 	void	(*close)(void);
 	void	*data;
 };

arch/powerpc/boot/serial.c

@@ -33,7 +33,7 @@ static void serial_write(const char *buf, int len)
 		scdp->putc(*buf++);
 }
 
-static void serial_edit_cmdline(char *buf, int len)
+static void serial_edit_cmdline(char *buf, int len, unsigned int timeout)
 {
 	int timer = 0, count;
 	char ch, *cp;
@@ -44,7 +44,7 @@ static void serial_edit_cmdline(char *buf, int len)
 	cp = &buf[count];
 	count++;
 
-	while (timer++ < 5*1000) {
+	do {
 		if (scdp->tstc()) {
 			while (((ch = scdp->getc()) != '\n') && (ch != '\r')) {
 				/* Test for backspace/delete */
@@ -70,7 +70,7 @@ static void serial_edit_cmdline(char *buf, int len)
 			break;  /* Exit 'timer' loop */
 		}
 		udelay(1000);  /* 1 msec */
-	}
+	} while (timer++ < timeout);
 	*cp = 0;
 }