buspirate: Add option for setting the aux pin

This adds a parameter to drive the aux pin low (or high if you
explicitly want the previous behavior). Some boards need to have a reset
pin driven low before the firmware can be safely flashed. With the Bus
Pirate, this is most easily done with the auxiliary pin.

Change-Id: Ieeecfdf1afc06dadda9b8f99547cd74854ca6775
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/43608
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Thomas Heijligen <src@posteo.de>
---
M buspirate_spi.c
M doc/classic_cli_manpage.rst
2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/buspirate_spi.c b/buspirate_spi.c
index d3114c4..72c28b0 100644
--- a/buspirate_spi.c
+++ b/buspirate_spi.c
@@ -327,6 +327,7 @@
 	int ret = 0;
 	bool pullup = false;
 	bool psu = false;
+	bool aux = true;
 	unsigned char *bp_commbuf;
 	int bp_commbufsize;
 
@@ -389,6 +390,17 @@
 	}
 	free(tmp);
 
+	tmp = extract_programmer_param_str(cfg, "aux");
+	if (tmp) {
+		if (strcasecmp("high", tmp) == 0)
+			; /* Default */
+		else if (strcasecmp("low", tmp) == 0)
+			aux = false;
+		else
+			msg_perr("Invalid AUX state, driving high by default.\n");
+	}
+	free(tmp);
+
 	/* Default buffer size is 19: 16 bytes data, 3 bytes control. */
 #define DEFAULT_BUFSIZE (16 + 3)
 	bp_commbuf = malloc(DEFAULT_BUFSIZE);
@@ -642,8 +654,8 @@
 		goto init_err_cleanup_exit;
 	}
 
-	/* Initial setup (SPI peripherals config): Enable power, CS high, AUX */
-	bp_commbuf[0] = 0x40 | 0x0b;
+	/* Initial setup (SPI peripherals config): Enable power, CS high */
+	bp_commbuf[0] = 0x40 | 0x09;
 	if (pullup) {
 		bp_commbuf[0] |= (1 << 2);
 		msg_pdbg("Enabling pull-up resistors.\n");
@@ -652,6 +664,12 @@
 		bp_commbuf[0] |= (1 << 3);
 		msg_pdbg("Enabling PSUs.\n");
 	}
+	if (aux) {
+		bp_commbuf[0] |= (1 << 1);
+		msg_pdbg("Driving AUX high.\n");
+	} else {
+		msg_pdbg("Driving AUX low.\n");
+	}
 	ret = buspirate_sendrecv(bp_commbuf, 1, 1);
 	if (ret)
 		goto init_err_cleanup_exit;
diff --git a/doc/classic_cli_manpage.rst b/doc/classic_cli_manpage.rst
index d46d9ca..45ef4aa 100644
--- a/doc/classic_cli_manpage.rst
+++ b/doc/classic_cli_manpage.rst
@@ -780,6 +780,14 @@
 This allows the bus pirate to power the ROM chip directly. This may also be used to provide the required pullup voltage
 (when using the **pullups** option), by connecting the Bus Pirate's Vpu input to the appropriate Vcc pin.
 
+An optional aux parameter specifies the state of the Bus Pirate auxiliary pin.
+This may be used to drive the auxiliary pin high or low before a transfer.
+Syntax is::
+
+        flashrom -p buspirate_spi:aux=state
+
+where ``state`` can be ``high`` or ``low``. The default ``state`` is ``high``.
+
 
 pickit2_spi programmer
 ^^^^^^^^^^^^^^^^^^^^^^

