[MTD] [NAND] Hardware ECC controller on at91sam9263 / at91sam9260

This is a patch to use the hardware ECC controller of
the AT91SAM9260 and AT91SAM9263 for the AT91 nand.
On AT91 NAND, there's now a choice between ECC soft,
ECC hard or no ECC (for debug).

It has been tested on AT91SAM9263 with 8 bits large
and small page NAND.
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/nand/Kconfig

@@ -278,6 +278,47 @@ config MTD_NAND_AT91
 	help
 	  Enables support for NAND Flash / Smart Media Card interface
 	  on Atmel AT91 processors.
+choice
+	prompt "ECC management for NAND Flash / SmartMedia on AT91"
+	depends on MTD_NAND_AT91
+
+config MTD_NAND_AT91_ECC_HW
+	bool "Hardware ECC"
+	depends on ARCH_AT91SAM9263 || ARCH_AT91SAM9260
+	help
+	  Uses hardware ECC provided by the at91sam9260/at91sam9263 chip
+	  instead of software ECC.
+	  The hardware ECC controller is capable of single bit error
+	  correction and 2-bit random detection per page.
+
+	  NB : hardware and software ECC schemes are incompatible.
+	  If you switch from one to another, you'll have to erase your
+	  mtd partition.
+
+	  If unsure, say Y
+
+config MTD_NAND_AT91_ECC_SOFT
+	bool "Software ECC"
+	help
+	  Uses software ECC.
+
+	  NB : hardware and software ECC schemes are incompatible.
+	  If you switch from one to another, you'll have to erase your
+	  mtd partition.
+
+config MTD_NAND_AT91_ECC_NONE
+	bool "No ECC (testing only, DANGEROUS)"
+	depends on DEBUG_KERNEL
+	help
+	  No ECC will be used.
+	  It's not a good idea and it should be reserved for testing
+	  purpose only.
+
+	  If unsure, say N
+
+	  endchoice
+
+endchoice
 
 config MTD_NAND_PXA3xx
 	bool "Support for NAND flash devices on PXA3xx"