File 0001-Bus-Pirate-UART-speedup.patch of Package flashrom

From 944bdbfcb9daf6e48c8c51915aaed759d5b68f70 Mon Sep 17 00:00:00 2001
From: Bernie Innocenti <bernie@codewiz.org>
Date: Mon, 18 Aug 2014 02:40:28 +0000
Subject: Bus Pirate UART speedup

I'm reposting this patch sent by Stefan Tauner in April,
after rebasing it onto flashrom's svn trunk.

Compared to the original, there's just one change: the original patch
did set the host uart speed back to 115200 (which is a no-op).
So I changed the baudrate to 2000000 (2Mbit), making the code agree
with the description.

I tested the patched flashrom with a Buspirate v3 running the 6.2beta
firmware. While I didn't make any accurate measurements, I'd
guesstimate a 10x speedup with my 8MB SPI flash. WOAH!
---
 buspirate_spi.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/buspirate_spi.c b/buspirate_spi.c
index b6554ac..5d9c32f 100644
--- a/buspirate_spi.c
+++ b/buspirate_spi.c
@@ -178,7 +178,10 @@ static int buspirate_spi_shutdown(void *data)
 	}
 	/* Reset Bus Pirate (return to user terminal) */
 	bp_commbuf[0] = 0x0f;
-	ret = buspirate_sendrecv(bp_commbuf, 1, 0);
+	if ((ret = buspirate_sendrecv(bp_commbuf, 1, 0)))
+		goto out_shutdown;
+	if ((ret = serialport_config(sp_fd, 115200)))
+		goto out_shutdown;
 
 out_shutdown:
 	/* Shut down serial port communication */
@@ -370,6 +373,45 @@ int buspirate_spi_init(void)
 		spi_master_buspirate.command = buspirate_spi_send_command_v1;
 	}
 
+	/* Increase PIC/FT232 UART speed to 2 Mbaud (instead of 115200 baud) in firmware 5.5 and newer.
+	 * Although this is already possible in firmware 5.2, fast UART in combination with the old SPI
+	 * command set causes hangs for bigger transactions. This is caused by a UART buffer overrun
+	 * in the PIC, and all firmware versions up to (hopefully not including) 6.2 are affected.
+	 */
+	if (BP_FWVERSION(fw_version_major, fw_version_minor) >= BP_FWVERSION(5, 5)) {
+		// FIXME: Do this only for USB-based Bus Pirates... unless you're sure the UART can handle more.
+		int cmdlen;
+		/* Request setting the UART baud rate. */
+		cmdlen = snprintf((char *)bp_commbuf, DEFAULT_BUFSIZE, "b\n");
+		if ((ret = buspirate_sendrecv(bp_commbuf, cmdlen, 0)))
+			return ret;
+		if ((ret = buspirate_wait_for_string(bp_commbuf, ">")))
+			return ret;
+		/* Request setting the UART clock divisor manually. */
+		cmdlen = snprintf((char *)bp_commbuf, DEFAULT_BUFSIZE, "10\n");
+		if ((ret = buspirate_sendrecv(bp_commbuf, cmdlen, 0)))
+			return ret;
+		if ((ret = buspirate_wait_for_string(bp_commbuf, ">")))
+			return ret;
+		/* Set the UART clock divisor. New clock is 4000000/(divisor+1). */
+		cmdlen = snprintf((char *)bp_commbuf, DEFAULT_BUFSIZE, "%i\n", 1);
+		if ((ret = buspirate_sendrecv(bp_commbuf, cmdlen, 0)))
+			return ret;
+		sleep(1);
+		if (serialport_config(sp_fd, 2000000) != 0)
+			return 1;
+		bp_commbuf[0] = ' ';
+		if ((ret = buspirate_sendrecv(bp_commbuf, 1, 0)))
+			return ret;
+		if ((ret = buspirate_wait_for_string(bp_commbuf, "HiZ>")))
+			return ret;
+		msg_pdbg("Using fast 2 Mbaud for Bus Pirate <-> host communication.\n");
+	} else {
+		msg_pinfo("Bus Pirate firmware 5.4 and older does not support fast Bus Pirate <-> host "
+			  "communication. Limiting UART speed to 115200 Baud.\n");
+		msg_pinfo("It is recommended to upgrade to firmware 6.2 or newer.\n");
+	}
+
 	/* Workaround for broken speed settings in firmware 6.1 and older. */
 	if (BP_FWVERSION(fw_version_major, fw_version_minor) < BP_FWVERSION(6, 2))
 		if (spispeed > 0x4) {
-- 
2.1.2