Verify data after writing

src/drivers/nvs/nvs.c

  */
 
 #include <stdint.h>
+#include <string.h>
+#include <errno.h>
 #include <assert.h>
 #include <gpxe/nvs.h>
 
 	return 0;
 }
 
+/**
+ * Verify content of non-volatile storage device
+ *
+ * @v nvs		NVS device
+ * @v address		Address from which to read
+ * @v data		Data to compare against
+ * @v len		Length of data buffer
+ * @ret rc		Return status code
+ */
+static int nvs_verify ( struct nvs_device *nvs, unsigned int address,
+			const void *data, size_t len ) {
+	uint8_t read_data[len];
+	int rc;
+
+	/* Read data into temporary buffer */
+	if ( ( rc = nvs_read ( nvs, address, read_data, len ) ) != 0 )
+		return rc;
+
+	/* Compare data */
+	if ( memcmp ( data, read_data, len ) != 0 ) {
+		DBG ( "NVS %p verification failed at %#04x+%d\n",
+		      nvs, address, len );
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * Write to non-volatile storage device
  *
 		if ( frag_len > len )
 			frag_len = len;
 
-		/* Read this portion of the buffer from the device */
+		/* Write this portion of the buffer to the device */
 		if ( ( rc = nvs->write ( nvs, address, data, frag_len ) ) != 0)
 			return rc;
 
+		/* Read back and verify data */
+		if ( ( rc = nvs_verify ( nvs, address, data, frag_len ) ) != 0)
+			return rc;
+
 		/* Update parameters */
 		data += frag_len;
 		address += ( frag_len >> nvs->word_len_log2 );