1 files changed, 132 insertions, 0 deletions
diff --git a/src/include/gpxe/spi.h b/src/include/gpxe/spi.h
new file mode 100644
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+++ b/src/include/gpxe/spi.h
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+#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 */