[MTD] OneNAND: Amend write-verify to compare to original buffer

When write-verify is enabled (CONFIG_MTD_ONENAND_VERIFY_WRITE),
the data written is read back and compared.  The comparison
was being made between dataRAM buffers, but this does not
verify that the data made it to the dataRAM correctly in
the first place.  This patch amends write-verify to
compare back to the original buffer.  It also now verifies
sub-page writes.
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

drivers/mtd/onenand/onenand_base.c

@@ -909,41 +909,51 @@ static int onenand_verify_oob(struct mtd_info *mtd, const u_char *buf, loff_t to
 }
 
 /**
- * onenand_verify_page - [GENERIC] verify the chip contents after a write
+ * onenand_verify - [GENERIC] verify the chip contents after a write
  * @param mtd          MTD device structure
  * @param buf          the databuffer to verify
+ * @param addr         offset to read from
+ * @param len          number of bytes to read and compare
  *
- * Check DataRAM area directly
  */
-static int onenand_verify_page(struct mtd_info *mtd, u_char *buf, loff_t addr)
+static int onenand_verify(struct mtd_info *mtd, const u_char *buf, loff_t addr, size_t len)
 {
 	struct onenand_chip *this = mtd->priv;
-	void __iomem *dataram0, *dataram1;
+	void __iomem *dataram;
 	int ret = 0;
+	int thislen, column;
 
-	/* In partial page write, just skip it */
-	if ((addr & (mtd->writesize - 1)) != 0)
-		return 0;
+	while (len != 0) {
+		thislen = min_t(int, mtd->writesize, len);
+		column = addr & (mtd->writesize - 1);
+		if (column + thislen > mtd->writesize)
+			thislen = mtd->writesize - column;
 
 		this->command(mtd, ONENAND_CMD_READ, addr, mtd->writesize);
 
+		onenand_update_bufferram(mtd, addr, 0);
+
 		ret = this->wait(mtd, FL_READING);
 		if (ret)
 			return ret;
 
 		onenand_update_bufferram(mtd, addr, 1);
 
-	/* Check, if the two dataram areas are same */
-	dataram0 = this->base + ONENAND_DATARAM;
-	dataram1 = dataram0 + mtd->writesize;
+		dataram = this->base + ONENAND_DATARAM;
+		dataram += onenand_bufferram_offset(mtd, ONENAND_DATARAM);
 
-	if (memcmp(dataram0, dataram1, mtd->writesize))
+		if (memcmp(buf, dataram + column, thislen))
 			return -EBADMSG;
 
+		len -= thislen;
+		buf += thislen;
+		addr += thislen;
+	}
+
 	return 0;
 }
 #else
-#define onenand_verify_page(...)	(0)
+#define onenand_verify(...)		(0)
 #define onenand_verify_oob(...)		(0)
 #endif
 
@@ -1025,7 +1035,7 @@ static int onenand_write(struct mtd_info *mtd, loff_t to, size_t len,
 		}
 
 		/* Only check verify write turn on */
-		ret = onenand_verify_page(mtd, (u_char *) wbuf, to);
+		ret = onenand_verify(mtd, (u_char *) wbuf, to, thislen);
 		if (ret) {
 			DEBUG(MTD_DEBUG_LEVEL0, "onenand_write: verify failed %d\n", ret);
 			break;