mtd: nand: mxic-ecc: Add Macronix external ECC engine support

Some SPI-NAND chips do not support on-die ECC. For these chips,
correction must apply on the SPI controller end. In order to avoid
doing all the calculations by software, Macronix provides a specific
engine that can offload the intensive work.

Add Macronix ECC engine support, this engine can work in conjunction
with a SPI controller and a raw NAND controller, it can be pipelined
or external and supports linear and syndrome layouts.

Right now the simplest configuration is supported: SPI controller
external and linear ECC engine.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211216111654.238086-15-miquel.raynal@bootlin.com

drivers/mtd/nand/Kconfig

@@ -46,6 +46,12 @@ config MTD_NAND_ECC_SW_BCH
 	  ECC codes. They are used with NAND devices requiring more than 1 bit
 	  of error correction.
 
+config MTD_NAND_ECC_MXIC
+	bool "Macronix external hardware ECC engine"
+	select MTD_NAND_ECC
+	help
+	  This enables support for the hardware ECC engine from Macronix.
+
 endmenu
 
 endmenu

drivers/mtd/nand/Makefile

@@ -10,3 +10,4 @@ obj-y	+= spi/
 nandcore-$(CONFIG_MTD_NAND_ECC) += ecc.o
 nandcore-$(CONFIG_MTD_NAND_ECC_SW_HAMMING) += ecc-sw-hamming.o
 nandcore-$(CONFIG_MTD_NAND_ECC_SW_BCH) += ecc-sw-bch.o
+nandcore-$(CONFIG_MTD_NAND_ECC_MXIC) += ecc-mxic.o