1 files changed, 88 insertions, 0 deletions
diff --git a/gpxe/src/drivers/nvs/threewire.c b/gpxe/src/drivers/nvs/threewire.c
new file mode 100644
index 00000000..dbecf909
--- /dev/null
+++ b/gpxe/src/drivers/nvs/threewire.c
@@ -0,0 +1,88 @@
+/*
+ * 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 <assert.h>
+#include <unistd.h>
+#include <gpxe/threewire.h>
+
+/** @file
+ *
+ * Three-wire serial devices
+ *
+ */
+
+/**
+ * Read data from three-wire 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 threewire_read ( struct nvs_device *nvs, unsigned int address,
+		     void *data, size_t len ) {
+	struct spi_device *device = nvs_to_spi ( nvs );
+	struct spi_bus *bus = device->bus;
+
+	assert ( bus->mode == SPI_MODE_THREEWIRE );
+
+	DBG ( "3wire %p reading %zd bytes at %04x\n", device, len, address );
+
+	return bus->rw ( bus, device, THREEWIRE_READ, address,
+			 NULL, data, len );
+}
+
+/**
+ * Write data to three-wire 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 threewire_write ( struct nvs_device *nvs, unsigned int address,
+		      const void *data, size_t len ) {
+	struct spi_device *device = nvs_to_spi ( nvs );
+	struct spi_bus *bus = device->bus;
+	int rc;
+
+	assert ( bus->mode == SPI_MODE_THREEWIRE );
+
+	DBG ( "3wire %p writing %zd bytes at %04x\n", device, len, address );
+
+	/* Enable device for writing */
+	if ( ( rc = bus->rw ( bus, device, THREEWIRE_EWEN,
+			      THREEWIRE_EWEN_ADDRESS, NULL, NULL, 0 ) ) != 0 )
+		return rc;
+
+	/* Write data */
+	if ( ( rc = bus->rw ( bus, device, THREEWIRE_WRITE, address,
+			      data, NULL, len ) ) != 0 )
+		return rc;
+
+	/* Our model of an SPI bus doesn't provide a mechanism for
+	 * "assert CS, wait for MISO to become high, so just wait for
+	 * long enough to ensure that the write has completed.
+	 */
+	mdelay ( THREEWIRE_WRITE_MDELAY );
+
+	return 0;
+}