Added the generic block-splitting code to nvs.c

src/drivers/nvs/nvs.c

@@ -17,6 +17,7 @@
  */
 
 #include <stdint.h>
+#include <assert.h>
 #include <gpxe/nvs.h>
 
 /** @file
@@ -25,7 +26,45 @@
  *
  */
 
+/**
+ * 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;
 }