mtd: atmel_nand: according to pmecc version to perform 0xff page correction

As the PMECC hardware has different version. In SAMA5D4 chip, the PMECC ip
can generate 0xff pmecc ECC value for all 0xff sector.

According to this, add PMECC version check, if it's SAMA5D4 then we always
let PMECC hardware to correct it.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 620b6e8..b16e3aa 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -44,6 +44,7 @@
 	u8		pmecc_corr_cap;
 	u16		pmecc_sector_size;
 	u32		pmecc_index_table_offset;
+	u32		pmecc_version;
 
 	int		pmecc_bytes_per_sector;
 	int		pmecc_sector_number;
@@ -486,6 +487,10 @@
 	int i, err_nbr, eccbytes;
 	uint8_t *buf_pos;
 
+	/* SAMA5D4 PMECC IP can correct errors for all 0xff page */
+	if (host->pmecc_version >= PMECC_VERSION_SAMA5D4)
+		goto normal_check;
+
 	eccbytes = nand_chip->ecc.bytes;
 	for (i = 0; i < eccbytes; i++)
 		if (ecc[i] != 0xff)
@@ -961,6 +966,10 @@
 	nand->ecc.write_page = atmel_nand_pmecc_write_page;
 	nand->ecc.strength = cap;
 
+	/* Check the PMECC ip version */
+	host->pmecc_version = pmecc_readl(host->pmerrloc, version);
+	dev_dbg(host->dev, "PMECC IP version is: %x\n", host->pmecc_version);
+
 	atmel_pmecc_core_init(mtd);
 
 	return 0;