[PATCH u-boot-marvell 09/14] tools: kwboot: Force BootROM to flush input queue after boot pattern

Marek Behún
2022-01-25T17:15:00Z

From: Pali Rohár <pali@kernel.org>

Force the BootROM to flush its input queue after sending boot pattern.

This ensures that after function kwboot_bootmsg() finishes, BootROM is
able to start receiving xmodem packets without any specific delay or
setup.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <marek.behun@nic.cz>
---
tools/kwboot.c | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/tools/kwboot.c b/tools/kwboot.c
index c413a8bf51..824ae005b2 100644
--- a/tools/kwboot.c
+++ b/tools/kwboot.c
@@ -717,6 +717,7 @@ out:
static int
kwboot_bootmsg(int tty, void *msg)
{
+ struct kwboot_block block;
int rc;
char c;
int count;
@@ -747,7 +748,40 @@ kwboot_bootmsg(int tty, void *msg)

kwboot_printv("\n");

- return rc;
+ if (rc)
+ return rc;
+
+ /*
+ * At this stage we have sent more boot message patterns and BootROM
+ * (at least on Armada XP and 385) started interpreting sent bytes as
+ * part of xmodem packets. If BootROM is expecting SOH byte as start of
+ * a xmodem packet and it receives byte 0xff, then it throws it away and
+ * sends a NAK reply to host. If BootROM does not receive any byte for
+ * 2s when expecting some continuation of the xmodem packet, it throws
+ * away the partially received xmodem data and sends NAK reply to host.
+ *
+ * Therefore for starting xmodem transfer we have two options: Either
+ * wait 2s or send 132 0xff bytes (which is the size of xmodem packet)
+ * to ensure that BootROM throws away any partially received data.
+ */
+
+ /* flush output queue with remaining boot message patterns */
+ tcflush(tty, TCOFLUSH);
+
+ /* send one xmodem packet with 0xff bytes to force BootROM to re-sync */
+ memset(&block, 0xff, sizeof(block));
+ kwboot_tty_send(tty, &block, sizeof(block), 0);
+
+ /*
+ * Sending 132 bytes via 115200B/8-N-1 takes 11.45 ms, reading 132 bytes
+ * takes 11.45 ms, so waiting for 30 ms should be enough.
+ */
+ usleep(30 * 1000);
+
+ /* flush remaining NAK replies from input queue */
+ tcflush(tty, TCIFLUSH);
+
+ return 0;
}

static int
--
2.34.1