mtd: atmel_nand: add Nand Flash Controller (NFC) support

Nand Flash Controller (NFC) can handle automatic transfers, sending the
commands and address cycles to the NAND Flash.

To use NFC in this driver, user needs to add NFC child node in nand flash
driver. The NFC child node includes NFC's compatible string and regiters
of the address and size of NFC command registers, NFC registers (embedded
in HSMC) and NFC SRAM.
Also user need to set up the HSMC irq, which use to check whether nfc
command is finish or not.

This driver has been tested on SAMA5D3X-EK board with JFFS2, YAFFS,
UBIFS and mtd-utils.

I put the part of the mtd_speedtest result here for your information.
>From the mtd_speedtest, we can see the NFC will reduce the %50 of cpu load
when writing nand flash. No change when reading.
In the meantime, the speed will be slow about %8.

- commands use to test:
    #insmod /mnt/mtd_speedtest.ko dev=2 &
    #top -n 30 -d 1 | grep speedtest

- test result:

Before the patch:
=================================================
mtd_speedtest: MTD device: 2
mtd_speedtest: MTD device size 41943040, eraseblock size 131072, page size 2048, count of eraseblocks 320, pages per eraseblock 64, OOB size 64
  515   495 root     R     1164   0%  93% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  98% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  99% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: eraseblock write speed is 5768 KiB/s
mtd_speedtest: testing eraseblock read speed
  515   495 root     R     1164   0%  92% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  91% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  94% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: eraseblock read speed is 5932 KiB/s
mtd_speedtest: testing page write speed
  515   495 root     R     1164   0%  94% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  98% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  98% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: page write speed is 5770 KiB/s
mtd_speedtest: testing page read speed
  515   495 root     R     1164   0%  91% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  89% insmod /mnt/mtd_speedtest.ko dev=2
  515   495 root     R     1164   0%  91% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: page read speed is 5910 KiB/s

After the patch:
=================================================
mtd_speedtest: MTD device: 2
mtd_speedtest: MTD device size 41943040, eraseblock size 131072, page size 2048, count of eraseblocks 320, pages per eraseblock 64, OOB size 64
mtd_speedtest: testing eraseblock write speed
  509   495 root     D     1164   0%  49% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     D     1164   0%  50% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     D     1164   0%  47% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: eraseblock write speed is 5370 KiB/s
mtd_speedtest: testing eraseblock read speed
  509   495 root     R     1164   0%  92% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     R     1164   0%  91% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     R     1164   0%  95% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: eraseblock read speed is 5715 KiB/s
mtd_speedtest: testing page write speed
  509   495 root     D     1164   0%  48% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     D     1164   0%  47% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     D     1164   0%  50% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: page write speed is 5224 KiB/s
mtd_speedtest: testing page read speed
  509   495 root     R     1164   0%  89% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     R     1164   0%  94% insmod /mnt/mtd_speedtest.ko dev=2
  509   495 root     R     1164   0%  93% insmod /mnt/mtd_speedtest.ko dev=2
mtd_speedtest: page read speed is 5641 KiB/s
Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Documentation/devicetree/bindings/mtd/atmel-nand.txt

@@ -30,6 +30,12 @@ Optional properties:
   sector size 1024.
 - nand-bus-width : 8 or 16 bus width if not present 8
 - nand-on-flash-bbt: boolean to enable on flash bbt option if not present false
+- Nand Flash Controller(NFC) is a slave driver under Atmel nand flash
+  - Required properties:
+    - compatible : "atmel,sama5d3-nfc".
+    - reg : should specify the address and size used for NFC command registers,
+            NFC registers and NFC Sram. NFC Sram address and size can be absent
+            if don't want to use it.
 
 Examples:
 nand0: nand@40000000,0 {
@@ -78,3 +84,22 @@ nand0: nand@40000000 {
 		...
 	};
 };
+
+/* for NFC supported chips */
+nand0: nand@40000000 {
+	compatible = "atmel,at91rm9200-nand";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	ranges;
+        ...
+        nfc@70000000 {
+		compatible = "atmel,sama5d3-nfc";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		reg = <
+			0x70000000 0x10000000	/* NFC Command Registers */
+			0xffffc000 0x00000070	/* NFC HSMC regs */
+			0x00200000 0x00100000	/* NFC SRAM banks */
+		>;
+	};
+};

drivers/mtd/nand/atmel_nand_nfc.h

+/*
+ * Atmel Nand Flash Controller (NFC) - System peripherals regsters.
+ * Based on SAMA5D3 datasheet.
+ *
+ * © Copyright 2013 Atmel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#ifndef ATMEL_NAND_NFC_H
+#define ATMEL_NAND_NFC_H
+
+/*
+ * HSMC NFC registers
+ */
+#define ATMEL_HSMC_NFC_CFG	0x00		/* NFC Configuration Register */
+#define		NFC_CFG_PAGESIZE	(7 << 0)
+#define			NFC_CFG_PAGESIZE_512	(0 << 0)
+#define			NFC_CFG_PAGESIZE_1024	(1 << 0)
+#define			NFC_CFG_PAGESIZE_2048	(2 << 0)
+#define			NFC_CFG_PAGESIZE_4096	(3 << 0)
+#define			NFC_CFG_PAGESIZE_8192	(4 << 0)
+#define		NFC_CFG_WSPARE		(1 << 8)
+#define		NFC_CFG_RSPARE		(1 << 9)
+#define		NFC_CFG_NFC_DTOCYC	(0xf << 16)
+#define		NFC_CFG_NFC_DTOMUL	(0x7 << 20)
+#define		NFC_CFG_NFC_SPARESIZE	(0x7f << 24)
+#define		NFC_CFG_NFC_SPARESIZE_BIT_POS	24
+
+#define ATMEL_HSMC_NFC_CTRL	0x04		/* NFC Control Register */
+#define		NFC_CTRL_ENABLE		(1 << 0)
+#define		NFC_CTRL_DISABLE	(1 << 1)
+
+#define ATMEL_HSMC_NFC_SR	0x08		/* NFC Status Register */
+#define		NFC_SR_XFR_DONE		(1 << 16)
+#define		NFC_SR_CMD_DONE		(1 << 17)
+#define		NFC_SR_RB_EDGE		(1 << 24)
+
+#define ATMEL_HSMC_NFC_IER	0x0c
+#define ATMEL_HSMC_NFC_IDR	0x10
+#define ATMEL_HSMC_NFC_IMR	0x14
+#define ATMEL_HSMC_NFC_CYCLE0	0x18		/* NFC Address Cycle Zero */
+#define		ATMEL_HSMC_NFC_ADDR_CYCLE0	(0xff)
+
+#define ATMEL_HSMC_NFC_BANK	0x1c		/* NFC Bank Register */
+#define		ATMEL_HSMC_NFC_BANK0		(0 << 0)
+#define		ATMEL_HSMC_NFC_BANK1		(1 << 0)
+
+#define nfc_writel(addr, reg, value) \
+	writel((value), (addr) + ATMEL_HSMC_NFC_##reg)
+
+#define nfc_readl(addr, reg) \
+	readl_relaxed((addr) + ATMEL_HSMC_NFC_##reg)
+
+/*
+ * NFC Address Command definitions
+ */
+#define NFCADDR_CMD_CMD1	(0xff << 2)	/* Command for Cycle 1 */
+#define NFCADDR_CMD_CMD1_BIT_POS	2
+#define NFCADDR_CMD_CMD2	(0xff << 10)	/* Command for Cycle 2 */
+#define NFCADDR_CMD_CMD2_BIT_POS	10
+#define NFCADDR_CMD_VCMD2	(0x1 << 18)	/* Valid Cycle 2 Command */
+#define NFCADDR_CMD_ACYCLE	(0x7 << 19)	/* Number of Address required */
+#define		NFCADDR_CMD_ACYCLE_NONE		(0x0 << 19)
+#define		NFCADDR_CMD_ACYCLE_1		(0x1 << 19)
+#define		NFCADDR_CMD_ACYCLE_2		(0x2 << 19)
+#define		NFCADDR_CMD_ACYCLE_3		(0x3 << 19)
+#define		NFCADDR_CMD_ACYCLE_4		(0x4 << 19)
+#define		NFCADDR_CMD_ACYCLE_5		(0x5 << 19)
+#define NFCADDR_CMD_ACYCLE_BIT_POS	19
+#define NFCADDR_CMD_CSID	(0x7 << 22)	/* Chip Select Identifier */
+#define		NFCADDR_CMD_CSID_0		(0x0 << 22)
+#define		NFCADDR_CMD_CSID_1		(0x1 << 22)
+#define		NFCADDR_CMD_CSID_2		(0x2 << 22)
+#define		NFCADDR_CMD_CSID_3		(0x3 << 22)
+#define		NFCADDR_CMD_CSID_4		(0x4 << 22)
+#define		NFCADDR_CMD_CSID_5		(0x5 << 22)
+#define		NFCADDR_CMD_CSID_6		(0x6 << 22)
+#define		NFCADDR_CMD_CSID_7		(0x7 << 22)
+#define NFCADDR_CMD_DATAEN	(0x1 << 25)	/* Data Transfer Enable */
+#define NFCADDR_CMD_DATADIS	(0x0 << 25)	/* Data Transfer Disable */
+#define NFCADDR_CMD_NFCRD	(0x0 << 26)	/* NFC Read Enable */
+#define NFCADDR_CMD_NFCWR	(0x1 << 26)	/* NFC Write Enable */
+#define NFCADDR_CMD_NFCBUSY	(0x1 << 27)	/* NFC Busy */
+
+#define nfc_cmd_addr1234_writel(cmd, addr1234, nfc_base) \
+	writel((addr1234), (cmd) + nfc_base)
+
+#define nfc_cmd_readl(bitstatus, nfc_base) \
+	readl_relaxed((bitstatus) + nfc_base)
+
+#define NFC_TIME_OUT_MS		100
+#define	NFC_SRAM_BANK1_OFFSET	0x1200
+
+#endif