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

used on RTL8139 cards).

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 */