Added generic SPI protocol handler with read and write support.

1 files changed, 122 insertions, 0 deletions

diff --git a/src/drivers/nvs/spi.c b/src/drivers/nvs/spi.c
new file mode 100644
index 00000000..a4e6868c
--- /dev/null
+++ b/src/drivers/nvs/spi.c
@@ -0,0 +1,122 @@
+/*
+ * 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 <stddef.h>
+#include <errno.h>
+#include <timer.h>
+#include <gpxe/spi.h>
+
+/** @file
+ *
+ * SPI devices
+ *
+ */
+
+/**
+ * Munge SPI device address into command
+ *
+ * @v command		SPI command
+ * @v address		Address
+ * @v munge_address	Device requires address munging
+ * @ret command		Actual SPI command to use
+ *
+ * Some devices with 9-bit addresses (e.g. AT25040A EEPROM) use bit 3
+ * of the command byte as address bit A8, rather than having a
+ * two-byte address.  This function takes care of generating the
+ * appropriate command.
+ */
+static inline unsigned int spi_command ( unsigned int command,
+					 unsigned int address,
+					 int munge_address ) {
+	return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
+}
+
+/**
+ * Wait for SPI device to complete operation
+ *
+ * @v device		SPI device
+ * @ret rc		Return status code
+ */
+static int spi_wait ( struct spi_device *device ) {
+	struct spi_bus *bus = device->bus;
+	uint8_t status;
+	int i;
+	int rc;
+
+	for ( i = 0 ; i < 50 ; i++ ) {
+		udelay ( 20 );
+		if ( ( rc = bus->rw ( bus, device, SPI_RDSR, -1, NULL,
+				      &status, sizeof ( status ) ) ) != 0 )
+			return rc;
+		if ( ! ( status & SPI_STATUS_NRDY ) )
+			return 0;
+	}
+	DBG ( "SPI %p timed out\n", device );
+	return -ETIMEDOUT;
+}
+
+/**
+ * Read data from SPI device
+ *
+ * @v nvs		NVS device
+ * @v address		Address from which to read
+ * @v data		Data buffer
+ * @v len		Length of data buffer
+ * @ret rc		Return status code
+ */
+int spi_read ( struct nvs_device *nvs, unsigned int address,
+	       void *data, unsigned int len ) {
+	struct spi_device *device = nvs_to_spi ( nvs );
+	struct spi_bus *bus = device->bus;
+	unsigned int command = spi_command ( SPI_READ, address,
+					     device->munge_address );
+
+	return bus->rw ( bus, device, command, address, NULL, data, len );
+}
+
+/**
+ * Write data to SPI device
+ *
+ * @v nvs		NVS device
+ * @v address		Address from which to read
+ * @v data		Data buffer
+ * @v len		Length of data buffer
+ * @ret rc		Return status code
+ */
+int spi_write ( struct nvs_device *nvs, unsigned int address,
+		const void *data, unsigned int len ) {
+	struct spi_device *device = nvs_to_spi ( nvs );
+	struct spi_bus *bus = device->bus;
+	unsigned int command = spi_command ( SPI_WRITE, address,
+					     device->munge_address );
+	int rc;
+
+	if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1,
+			      NULL, NULL, 0 ) ) != 0 )
+		return rc;
+
+	if ( ( rc = bus->rw ( bus, device, command, address,
+			      data, NULL, len ) ) != 0 )
+		return rc;
+	
+	if ( ( rc = spi_wait ( device ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+