[nvs] Allow for non-volatile storage devices without block boundaries

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/nvs/nvs.c

  *
  */
 
+/**
+ * Calculate length up to next block boundary
+ *
+ * @v nvs		NVS device
+ * @v address		Starting address
+ * @v max_len		Maximum length
+ * @ret len		Length to use, stopping at block boundaries
+ */
+static size_t nvs_frag_len ( struct nvs_device *nvs, unsigned int address,
+			     size_t max_len ) {
+	size_t frag_len;
+
+	/* If there are no block boundaries, return the maximum length */
+	if ( ! nvs->block_size )
+		return max_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 maximum length */
+	if ( max_len < frag_len )
+		return max_len;
+
+	return frag_len;
+}
+
 /**
  * Read from non-volatile storage device
  *
 
 	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;
+		/* Calculate length to read, stopping at block boundaries */
+		frag_len = nvs_frag_len ( nvs, address, len );
 
 		/* Read this portion of the buffer from the device */
 		if ( ( rc = nvs->read ( nvs, address, data, frag_len ) ) != 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;
+		/* Calculate length to write, stopping at block boundaries */
+		frag_len = nvs_frag_len ( nvs, address, len );
 
 		/* Write this portion of the buffer to the device */
 		if ( ( rc = nvs->write ( nvs, address, data, frag_len ) ) != 0)

src/drivers/nvs/nvsvpd.c

 	}
 
 	/* Initialise NVS device */
-	nvsvpd->nvs.block_size = 1;
 	nvsvpd->nvs.size = len;
 	nvsvpd->nvs.read = nvs_vpd_read;
 	nvsvpd->nvs.write = nvs_vpd_write;