mtd: nand: vf610_nfc: Freescale NFC for VF610, MPC5125 and others

This driver supports Freescale NFC (NAND flash controller) found on
Vybrid (VF610), MPC5125, MCF54418 and Kinetis K70. The driver has
been tested using 8-bit and 16-bit NAND interface on the ARM based
Vybrid SoC VF500 and VF610 platform.
parameter page reading.

Limitations:
- Untested on MPC5125 and M54418.
- DMA and pipelining not used.
- 2K pages or less.
- No chip select, one NAND chip per controller.
- No hardware ECC.

Some paths have been hand-optimized and evaluated by measurements
made using mtd_speedtest.ko on a 100MB MTD partition.

Colibri VF50
        eb write     %   eb read     %   page write      %   page read     %
rel/opt     5175           11537                4560             11039
opt         5164 -0.21     11420 -1.01          4737 +3.88       10918 -1.10
none        5113 -1.20     11352 -1.60          4490 -1.54       10865 -1.58

Colibri VF61
        eb write     %   eb read     %   page write      %   page read     %
rel/opt     5766           13096                5459             12846
opt         5883 +2.03     13064 -0.24          5561 +1.87       12802 -0.34
none        5701 -1.13     12980 -0.89          5488 +0.53       12735 -0.86

rel = using readl_relaxed/writel_relaxed in optimized paths
opt = hand-optimized by combining multiple accesses into one read/write

The measurements have not been statistically verfied, hence use them
with care. The author came to the conclusion that using the relaxed
variants of readl/writel are not worth the additional code.
Signed-off-by: Bill Pringlemeir <bpringlemeir@nbsps.com>
Tested-by: Albert ARIBAUD <albert.aribaud@3adev.fr>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Alexey Klimov <klimov.linux@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

MAINTAINERS

@@ -11056,6 +11056,12 @@ S:	Maintained
 F:	Documentation/fb/uvesafb.txt
 F:	drivers/video/fbdev/uvesafb.*
 
+VF610 NAND DRIVER
+M:	Stefan Agner <stefan@agner.ch>
+L:	linux-mtd@lists.infradead.org
+S:	Supported
+F:	drivers/mtd/nand/vf610_nfc.c
+
 VFAT/FAT/MSDOS FILESYSTEM
 M:	OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
 S:	Maintained

drivers/mtd/nand/Kconfig

@@ -460,6 +460,15 @@ config MTD_NAND_MPC5121_NFC
 	  This enables the driver for the NAND flash controller on the
 	  MPC5121 SoC.
 
+config MTD_NAND_VF610_NFC
+	tristate "Support for Freescale NFC for VF610/MPC5125"
+	depends on (SOC_VF610 || COMPILE_TEST)
+	help
+	  Enables support for NAND Flash Controller on some Freescale
+	  processors like the VF610, MPC5125, MCF54418 or Kinetis K70.
+	  The driver supports a maximum 2k page size. The driver
+	  currently does not support hardware ECC.
+
 config MTD_NAND_MXC
 	tristate "MXC NAND support"
 	depends on ARCH_MXC

drivers/mtd/nand/Makefile

@@ -46,6 +46,7 @@ obj-$(CONFIG_MTD_NAND_SOCRATES)		+= socrates_nand.o
 obj-$(CONFIG_MTD_NAND_TXX9NDFMC)	+= txx9ndfmc.o
 obj-$(CONFIG_MTD_NAND_NUC900)		+= nuc900_nand.o
 obj-$(CONFIG_MTD_NAND_MPC5121_NFC)	+= mpc5121_nfc.o
+obj-$(CONFIG_MTD_NAND_VF610_NFC)	+= vf610_nfc.o
 obj-$(CONFIG_MTD_NAND_RICOH)		+= r852.o
 obj-$(CONFIG_MTD_NAND_JZ4740)		+= jz4740_nand.o
 obj-$(CONFIG_MTD_NAND_GPMI_NAND)	+= gpmi-nand/