[U-Boot] [PATCH 2/2] RFC: Add XON/XOFF support

[Simon Glass]

This is just for testing - please try it out and report back with results.
For me it works on Minicom but not ser2net.

This needs to be controlled by an environment variable, CONFIG option or
both. We may need a way of specifying flow control on a per-device basis.
We may need to do something special for X-modem transfers, etc. This might
turn out to be a can of worms.

Signed-off-by: Simon Glass <sjg at chromium.org>
---
 common/command.c |    1 +
 common/console.c |   12 ++++++++++++
 common/main.c    |    3 +++
 include/common.h |    2 ++
 4 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/common/command.c b/common/command.c
index acc1c15..7b7c24e 100644
--- a/common/command.c
+++ b/common/command.c
@@ -492,6 +492,7 @@ int cmd_call(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int result;
 
+	console_suspend_input();
 	result = (cmdtp->cmd)(cmdtp, flag, argc, argv);
 	if (result)
 		debug("Command failed, result=%d", result);
diff --git a/common/console.c b/common/console.c
index f17875e..eeb58e6 100644
--- a/common/console.c
+++ b/common/console.c
@@ -199,6 +199,18 @@ static inline void console_doenv(int file, struct stdio_dev *dev)
 }
 #endif /* defined(CONFIG_CONSOLE_MUX) */
 
+void console_suspend_input(void)
+{
+	/* Send XOFF to tell the other end to stop sending */
+	console_putc(stdout, 'S' - '@');
+}
+
+void console_resume_input(void)
+{
+	/* Send XON to tell the other end to start sending */
+	console_putc(stdout, 'Q' - '@');
+}
+
 /** U-Boot INITIAL CONSOLE-NOT COMPATIBLE FUNCTIONS *************************/
 
 int serial_printf(const char *fmt, ...)
diff --git a/common/main.c b/common/main.c
index 3b60d27..b030176 100644
--- a/common/main.c
+++ b/common/main.c
@@ -948,6 +948,7 @@ int readline_into_buffer (const char *const prompt, char * buffer)
 
 		if (prompt)
 			puts (prompt);
+		console_resume_input();
 
 		rc = cread_line(prompt, p, &len);
 		return rc < 0 ? rc : len;
@@ -967,6 +968,8 @@ int readline_into_buffer (const char *const prompt, char * buffer)
 	}
 	col = plen;
 
+	console_resume_input();
+
 	for (;;) {
 #ifdef CONFIG_BOOT_RETRY_TIME
 		while (!tstc()) {	/* while no incoming data */
diff --git a/include/common.h b/include/common.h
index a1683a2..970ec0d 100644
--- a/include/common.h
+++ b/include/common.h
@@ -738,6 +738,8 @@ int	ctrlc (void);
 int	had_ctrlc (void);	/* have we had a Control-C since last clear? */
 void	clear_ctrlc (void);	/* clear the Control-C condition */
 int	disable_ctrlc (int);	/* 1 to disable, 0 to enable Control-C detect */
+void console_suspend_input(void);
+void console_resume_input(void);
 
 /*
  * STDIO based functions (can always be used)
-- 
1.7.3.1