Added abstraction layer for a three-wire serial device (e.g. the EEPROM

used on RTL8139 cards).

1 files changed, 68 insertions, 0 deletions

diff --git a/src/drivers/nvs/threewire.c b/src/drivers/nvs/threewire.c
new file mode 100644
index 00000000..4673606d
--- /dev/null
+++ b/src/drivers/nvs/threewire.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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; either version 2 of the
+ * License, or any later version.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <timer.h>
+#include <gpxe/nvs/threewire.h>
+
+/** @file
+ *
+ * Three-wire serial interface
+ *
+ */
+
+/**
+ * Read from a three-wire device
+ *
+ * @v three	Three-wire interface
+ * @v address	Address
+ * @ret data	Data
+ */
+unsigned long threewire_read ( struct threewire *three,
+			       unsigned long address ) {
+	struct threewire_operations *ops = three->ops;
+	unsigned long command;
+	unsigned long data;
+	int i;
+
+	ops->setcs ( three, 1 );
+	
+	/* Send command and address */
+	command = threewire_cmd_read ( three, address );
+	for ( i = ( threewire_cmd_len ( three ) - 1 ) ; i >= 0 ; i-- ) {
+		ops->setdi ( three, ( command >> i ) & 0x1 );
+		udelay ( three->udelay );
+		ops->setsk ( three, 1 );
+		udelay ( three->udelay );
+		ops->setsk ( three, 0 );
+	}
+
+	/* Read back data */
+	data = 0;
+	for ( i = three->datasize ; i ; i-- ) {
+		udelay ( three->udelay );
+		ops->setsk ( three, 1 );
+		udelay ( three->udelay );
+		data <<= 1;
+		data |= ops->getdo ( three );
+		ops->setsk ( three, 0 );
+	}
+
+	ops->setcs ( three, 0 );
+
+	return data;
+}