Generalise three-wire interface to generic SPI interface.

Update rtl8139 driver to instantiate an SPI interface with a three-wire
device attached.

src/include/gpxe/nvs/threewire.h

@@ -1,102 +0,0 @@
-#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 */

src/include/gpxe/spi.h

@@ -0,0 +1,132 @@
+#ifndef _GPXE_SPI_H
+#define _GPXE_SPI_H
+
+/** @file
+ *
+ * SPI interface
+ *
+ */
+
+#include <gpxe/bitbash.h>
+
+/** An SPI interface */
+struct spi_interface {
+	/** SPI interface mode
+	 *
+	 * This is the bitwise OR of zero or more of @c SPI_MODE_CPHA
+	 * and @c SPI_MODE_CPOL.  It is also the number conventionally
+	 * used to describe the SPI interface mode.  For example, SPI
+	 * mode 1 is the mode in which CPOL=0 and CPHA=1, which
+	 * therefore corresponds to a mode value of (0|SPI_MODE_CPHA)
+	 * which, happily, equals 1.
+	 */
+	unsigned int mode;
+	/**
+	 * Select slave
+	 *
+	 * @v spi		SPI interface
+	 * @v slave		Slave number
+	 */
+	void ( * select_slave ) ( struct spi_interface *spi,
+				  unsigned int slave );
+	/**
+	 * Deselect slave
+	 *
+	 * @v spi		SPI interface
+	 */
+	void ( * deselect_slave ) ( struct spi_interface *spi );
+	/**
+	 * Transfer bits over SPI bit-bashing interface
+	 *
+	 * @v spi		SPI interface
+	 * @v data_out		TX data buffer (or NULL)
+	 * @v data_in		RX data buffer (or NULL)
+	 * @v len		Length of transfer (in @b bits)
+	 */
+	void ( * transfer ) ( struct spi_interface *spi, const void *data_out,
+			      void *data_in, unsigned int len );
+};
+
+/** Clock phase (CPHA) mode bit
+ *
+ * Phase 0 is sample on rising edge, shift data on falling edge.
+ *
+ * Phase 1 is shift data on rising edge, sample data on falling edge.
+ */
+#define SPI_MODE_CPHA 0x01
+
+/** Clock polarity (CPOL) mode bit
+ *
+ * This bit reflects the idle state of the clock line (SCLK).
+ */
+#define SPI_MODE_CPOL 0x02
+
+/** Slave select polarity mode bit
+ *
+ * This bit reflects that active state of the slave select lines.  It
+ * is not part of the normal SPI mode number (which covers only @c
+ * SPI_MODE_CPOL and @c SPI_MODE_CPHA), but is included here for
+ * convenience.
+ */
+#define SPI_MODE_SSPOL 0x10
+
+/** Microwire-compatible mode
+ *
+ * This is SPI mode 1 (i.e. CPOL=0, CPHA=1), and is compatible with
+ * the original Microwire protocol.
+ */
+#define SPI_MODE_MICROWIRE 1
+
+/** Microwire/Plus-compatible mode
+ *
+ * This is SPI mode 0 (i.e. CPOL=0, CPHA=0), and is compatible with
+ * the Microwire/Plus protocol
+ */
+#define SPI_MODE_MICROWIRE_PLUS 0
+
+/** Threewire-compatible mode
+ *
+ * This mode is compatible with Atmel's series of "three-wire"
+ * interfaces.
+ */
+#define SPI_MODE_THREEWIRE ( SPI_MODE_MICROWIRE_PLUS | SPI_MODE_SSPOL )
+
+/** A bit-bashing SPI interface */
+struct spi_bit_basher {
+	/** SPI interface */
+	struct spi_interface spi;
+	/** Bit-bashing interface */
+	struct bit_basher basher;
+	/** Currently selected slave
+	 *
+	 * Valid only when a slave is actually selected.
+	 */
+	unsigned int slave;
+};
+
+/** Bit indices used for SPI bit-bashing interface */
+enum {
+	/** Serial clock */
+	SPI_BIT_SCLK = 0,
+	/** Master Out Slave In */
+	SPI_BIT_MOSI,
+	/** Master In Slave Out */
+	SPI_BIT_MISO,
+	/** Slave 0 select */
+	SPI_BIT_SS0,
+};
+
+/**
+ * Determine bit index for a particular slave
+ *
+ * @v slave		Slave number
+ * @ret index		Bit index (i.e. SPI_BIT_SSN, where N=slave) 
+ */
+#define SPI_BIT_SS( slave ) ( SPI_BIT_SS0 + (slave) )
+
+/** Delay between SCLK transitions */
+#define SPI_UDELAY 1
+
+extern void init_spi_bit_basher ( struct spi_bit_basher *spibit );
+
+#endif /* _GPXE_SPI_H */

src/include/gpxe/threewire.h

@@ -0,0 +1,65 @@
+#ifndef _GPXE_THREEWIRE_H
+#define _GPXE_THREEWIRE_H
+
+/** @file
+ *
+ * Three-wire serial interface
+ *
+ * The Atmel three-wire interface is a subset of the (newer) SPI
+ * interface, and is implemented here as a layer on top of the SPI
+ * support.
+ */
+
+struct spi_interface;
+
+/** A three-wire device */
+struct threewire_device {
+	/** SPI interface to which device is attached */
+	struct spi_interface *spi;
+	/** SPI slave number */
+	unsigned int slave;
+	/** Address size (in bits) */
+	unsigned int adrsize;
+	/** Data size (in bits) */
+	unsigned int datasize;
+};
+
+/**
+ * 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_device *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 )) unsigned int
+threewire_cmd_len ( struct threewire_device *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_device *three,
+				      unsigned long address );
+
+#endif /* _GPXE_THREEWIRE_H */