Added the generic block-splitting code to nvs.c

src/drivers/net/rtl8139.c

 	rtl->eeprom.bus = &rtl->spibit.bus;
 }
 
-/**
- * Read the MAC address
- *
- * @v rtl		RTL8139 NIC
- * @v mac_addr		Buffer to contain MAC address (ETH_ALEN bytes)
- */
-static void rtl_read_mac ( struct rtl8139_nic *rtl, uint8_t *mac_addr ) {
-
-	struct nvs_device *nvs = &rtl->eeprom.nvs;
-	int i;
-	
-	DBG ( "MAC address is " );
-	for ( i = EE_MAC ; i < ( EE_MAC + ( ETH_ALEN / 2 ) ) ; i++ ) {
-		nvs_read ( nvs, i, mac_addr, 2 );
-		DBG ( "%02x%02x", mac_addr[0], mac_addr[1] );
-		mac_addr += 2;
-	}
-	DBG ( "\n" );
-}
-
 /**
  * Reset NIC
  *
 	/* Reset the NIC, set up EEPROM access and read MAC address */
 	rtl_reset ( rtl );
 	rtl_init_eeprom ( rtl );
-	rtl_read_mac ( rtl, netdev->ll_addr );
+	nvs_read ( &rtl->eeprom.nvs, EE_MAC, netdev->ll_addr, ETH_ALEN );
 	
 	/* Point to NIC specific routines */
 	//	netdev->open	 = rtl_open;

src/drivers/nvs/nvs.c

  */
 
 #include <stdint.h>
+#include <assert.h>
 #include <gpxe/nvs.h>
 
 /** @file
  *
  */
 
+/**
+ * Read from non-volatile storage 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 nvs_read ( struct nvs_device *nvs, unsigned int address,
 	       void *data, size_t len ) {
-	return nvs->read ( nvs, address, data, len );
+	size_t frag_len;
+	int rc;
+
+	/* We don't even attempt to handle buffer lengths that aren't
+	 * an integral number of words.
+	 */
+	assert ( ( len & ( ( 1 << nvs->word_len_log2 ) - 1 ) ) == 0 );
+
+	while ( len ) {
+
+		/* Calculate space remaining up to next block boundary */
+		frag_len = ( ( nvs->block_size -
+			       ( address & ( nvs->block_size - 1 ) ) )
+			     << nvs->word_len_log2 );
+
+		/* Limit to space remaining in buffer */
+		if ( frag_len > len )
+			frag_len = len;
+
+		/* Read this portion of the buffer from the device */
+		if ( ( rc = nvs->read ( nvs, address, data, frag_len ) ) != 0 )
+			return rc;
+
+		/* Update parameters */
+		data += frag_len;
+		address += ( frag_len >> nvs->word_len_log2 );
+		len -= frag_len;
+	}
+
+	return 0;
 }

src/include/gpxe/nvs.h

 
 /** A non-volatile storage device */
 struct nvs_device {
-	/** Word length, in bits */
-	unsigned int word_len;
+	/** Word length
+	 *
+	 * This is expressed as the base-2 logarithm of the word
+	 * length in bytes.  A value of 0 therefore translates as
+	 * 8-bit words, and a value of 1 translates as 16-bit words.
+	 */
+	unsigned int word_len_log2;
 	/** Device size (in words) */
 	unsigned int size;
 	/** Data block size (in words)

src/include/gpxe/threewire.h

 
 static inline __attribute__ (( always_inline )) void
 init_at93cx6 ( struct spi_device *device, unsigned int organisation ) {
-	device->nvs.word_len = organisation;
+	device->nvs.word_len_log2 = ( ( organisation == 8 ) ? 0 : 1 );
 	device->nvs.block_size = 1;
 	device->command_len = 3,
 	device->nvs.read = threewire_read;