Add serial port bitbanging code

This adds the pony_spi driver which supports the SI_Prog adapter, which
is commonly used for SPI chips with PonyProg 2000, and a custom adapter
called "SERBANG" which differs in the logic of two pins.

Corresponding to flashrom svn r1525.

Signed-off-by: Virgil-Adrian Teaca <darkstarlinux@gmail.com>
Acked-by: Michael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
diff --git a/pony_spi.c b/pony_spi.c
new file mode 100644
index 0000000..b5dfc2f
--- /dev/null
+++ b/pony_spi.c
@@ -0,0 +1,160 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2012 Virgil-Adrian Teaca
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/* Driver for the SI-Prog like hardware by Lancos.com.
+ * See http://www.lancos.com/siprogsch.html for schematics and instructions.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "flash.h"
+#include "programmer.h"
+
+/* We have:
+
+ MOSI -----> DTR
+ MISO -----> CTS
+ SCK  --+--> RTS
+        +--> DSR
+ CS#  -----> TXD
+
+*/
+
+enum pony_type {
+	TYPE_SI_PROG,
+	TYPE_SERBANG,
+};
+
+/* The hardware programmer used. */
+static enum pony_type pony_type = TYPE_SI_PROG;
+
+static void pony_bitbang_set_cs(int val)
+{
+	if (pony_type == TYPE_SI_PROG)
+	{
+		/* CS# is negated by the SI-Prog programmer. */
+		val ^=  1;
+	}
+	sp_set_pin(PIN_TXD, val);
+}
+
+static void pony_bitbang_set_sck(int val)
+{
+	sp_set_pin(PIN_RTS, val);
+}
+
+static void pony_bitbang_set_mosi(int val)
+{
+	sp_set_pin(PIN_DTR, val);
+}
+
+static int pony_bitbang_get_miso(void)
+{
+	int tmp;
+
+	tmp = sp_get_pin(PIN_CTS);
+
+	if (pony_type == TYPE_SERBANG)
+	{
+		/* MISO is negated by the SERBANG programmer. */
+		tmp ^= 1;
+	}
+	return tmp;
+}
+
+static const struct bitbang_spi_master bitbang_spi_master_pony = {
+	.type = BITBANG_SPI_MASTER_PONY,
+	.set_cs = pony_bitbang_set_cs,
+	.set_sck = pony_bitbang_set_sck,
+	.set_mosi = pony_bitbang_set_mosi,
+	.get_miso = pony_bitbang_get_miso,
+	.half_period = 0,
+};
+
+int pony_spi_init(void)
+{
+	char *arg = NULL;
+	int i, data_in, data_out, have_device = 0;
+	int have_prog = 1;
+
+	/* The parameter is on format "dev=/dev/device,type=serbang" */
+	arg = extract_programmer_param("dev");
+
+	if (arg && strlen(arg)) {
+		sp_fd = sp_openserport( arg, 9600 );
+		have_device++;
+	}
+	free(arg);
+
+	if (!have_device) {
+		msg_perr("Error: No valid device specified.\n"
+			 "Use flashrom -p pony_spi:dev=/dev/device\n");
+
+		return 1;
+	}
+	/* Register the shutdown callback. */
+	if (register_shutdown(serialport_shutdown, NULL)) {
+		return 1;
+	}
+	arg = extract_programmer_param("type");
+
+	if (arg) {
+		if (!strcasecmp( arg, "serbang")) {
+			pony_type = TYPE_SERBANG;
+		} else if (!strcasecmp( arg, "si_prog") ) {
+			pony_type = TYPE_SI_PROG;
+		} else {
+			msg_perr("Error: Invalid programmer type specified.\n");
+			free(arg);
+			return 1;
+		}
+	}
+	free(arg);
+
+	msg_pdbg("Using the %s programmer.\n", ((pony_type == TYPE_SI_PROG ) ? "SI-Prog" : "SERBANG"));
+	/*
+	 * Detect if there is a SI-Prog compatible programmer connected.
+	 */
+	pony_bitbang_set_cs(1);
+	pony_bitbang_set_mosi(1);
+
+	/* We toggle SCK while we keep MOSI and CS# on. */
+	for (i = 1; i <= 10; ++i) {
+		data_out = i & 1;
+		sp_set_pin(PIN_RTS, data_out);
+		programmer_delay( 1000 );
+		data_in = sp_get_pin(PIN_DSR);
+
+		if (data_out != data_in) {
+			have_prog = 0;
+			break;
+		}
+	}
+
+	if (!have_prog) {
+		msg_perr( "No SI-Prog compatible hardware detected.\n" );
+		return 1;
+	}
+
+	if (bitbang_spi_init(&bitbang_spi_master_pony)) {
+		return 1;
+	}
+	return 0;
+}