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

used on RTL8139 cards).

src/Makefile

@@ -138,6 +138,7 @@ SRCDIRS		+= drivers/bus
 SRCDIRS		+= drivers/net
 SRCDIRS		+= drivers/block
 SRCDIRS		+= drivers/scsi
+SRCDIRS		+= drivers/nvs
 SRCDIRS		+= interface/pxe
 
 # NON_AUTO_SRCS lists files that are excluded from the normal

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;
+}

src/include/gpxe/nvs/threewire.h

@@ -0,0 +1,102 @@
+#ifndef _GPXE_NVS_THREEWIRE_H
+#define _GPXE_NVS_THREEWIRE_H
+
+/** @file
+ *
+ * Three-wire serial interface
+ *
+ */
+
+struct threewire;
+
+/** Three-wire interface methods */
+struct threewire_operations {
+	/**
+	 * Set status of Chip Select line
+	 *
+	 * @v three	Three-wire interface
+	 * @v cs	New status for chip select line
+	 */
+	void ( * setcs ) ( struct threewire *three, int cs );
+	/**
+	 * Set status of Serial Clock line
+	 *
+	 * @v three	Three-wire interface
+	 * @v sk	New status for serial clock line
+	 */
+	void ( * setsk ) ( struct threewire *three, int sk );
+	/**
+	 * Set status of Data Input line
+	 *
+	 * @v three	Three-wire interface
+	 * @v di	New status for data input line
+	 */
+	void ( * setdi ) ( struct threewire *three, int di );
+	/**
+	 * Get status of Data Output line
+	 *
+	 * @v three	Three-wire interface
+	 * @ret do	Status of data output line
+	 */
+	int ( * getdo ) ( struct threewire *three );
+};
+
+/**
+ * A three-wire serial interface
+ *
+ * This interface consists of a clock line (SK), data input (DI) and
+ * data output (DO).  There is also a chip select line (CS) which is
+ * integral to the operation of the device, but Atmel still calls it a
+ * three-wire interface.
+ *
+ */
+struct threewire {
+	/** Interface methods */
+	struct threewire_operations *ops;
+	/** Address size (in bits) */
+	unsigned int adrsize;
+	/** Data size (in bits) */
+	unsigned int datasize;
+	/** Delay between SK transitions (in us) */
+	unsigned int udelay;
+};
+
+/**
+ * Calculate read command for a specified address
+ *
+ * @v three	Three-wire interface
+ * @v address	Address
+ * @ret cmd	Command
+ */
+static inline __attribute__ (( always_inline )) unsigned long
+threewire_cmd_read ( struct threewire *three, unsigned long address ) {
+	return ( ( 0x6 << three->adrsize ) | address );
+}
+
+/**
+ * Calculate command length
+ *
+ * @v three	Three-wire interface
+ * @ret len	Command length, in bits
+ */
+static inline __attribute__ (( always_inline )) int
+threewire_cmd_len ( struct threewire *three ) {
+	return ( three->adrsize + 3 );
+}
+
+/* Constants for some standard parts */
+#define AT93C46_ORG8_ADRSIZE	7
+#define AT93C46_ORG8_DATASIZE	8
+#define AT93C46_ORG16_ADRSIZE	6
+#define AT93C46_ORG16_DATASIZE	16
+#define AT93C46_UDELAY		1
+#define AT93C56_ORG8_ADRSIZE	9
+#define AT93C56_ORG8_DATASIZE	8
+#define AT93C56_ORG16_ADRSIZE	8
+#define AT93C56_ORG16_DATASIZE	16
+#define AT93C56_UDELAY		1
+
+extern unsigned long threewire_read ( struct threewire *three,
+				      unsigned long address );
+
+#endif /* _GPXE_NVS_THREEWIRE_H */