lpc32xx: mtd: nand: add MLC NAND controller

The controller's Reed-Solomon ECC hardware is
used except of course for raw reads and writes.
It covers in- and out-of-band data together.

The SPL framework is supported.

Signed-off-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>

1 files changed, 764 insertions, 0 deletions

diff --git a/drivers/mtd/nand/lpc32xx_nand_mlc.c b/drivers/mtd/nand/lpc32xx_nand_mlc.c
new file mode 100644
index 0000000000..8156fe9613
--- /dev/null
+++ b/drivers/mtd/nand/lpc32xx_nand_mlc.c
@@ -0,0 +1,764 @@
+/*
+ * LPC32xx MLC NAND flash controller driver
+ *
+ * (C) Copyright 2014 3ADEV <http://3adev.com>
+ * Written by Albert ARIBAUD <albert.aribaud@3adev.fr>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ *
+ * NOTE:
+ *
+ * The MLC NAND flash controller provides hardware Reed-Solomon ECC
+ * covering in- and out-of-band data together. Therefore, in- and out-
+ * of-band data must be written together in order to have a valid ECC.
+ *
+ * Consequently, pages with meaningful in-band data are written with
+ * blank (all-ones) out-of-band data and a valid ECC, and any later
+ * out-of-band data write will void the ECC.
+ *
+ * Therefore, code which reads such late-written out-of-band data
+ * should not rely on the ECC validity.
+ */
+
+#include <common.h>
+#include <nand.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+#include <nand.h>
+#include <asm/arch/clk.h>
+#include <asm/arch/sys_proto.h>
+
+/*
+ * MLC NAND controller registers.
+ */
+struct lpc32xx_nand_mlc_registers {
+	u8 buff[32768]; /* controller's serial data buffer */
+	u8 data[32768]; /* NAND's raw data buffer */
+	u32 cmd;
+	u32 addr;
+	u32 ecc_enc_reg;
+	u32 ecc_dec_reg;
+	u32 ecc_auto_enc_reg;
+	u32 ecc_auto_dec_reg;
+	u32 rpr;
+	u32 wpr;
+	u32 rubp;
+	u32 robp;
+	u32 sw_wp_add_low;
+	u32 sw_wp_add_hig;
+	u32 icr;
+	u32 time_reg;
+	u32 irq_mr;
+	u32 irq_sr;
+	u32 lock_pr;
+	u32 isr;
+	u32 ceh;
+};
+
+/* LOCK_PR register defines */
+#define LOCK_PR_UNLOCK_KEY 0x0000A25E  /* Magic unlock value */
+
+/* ICR defines */
+#define ICR_LARGE_BLOCKS 0x00000004	/* configure for 2KB blocks */
+#define ICR_ADDR4        0x00000002	/* configure for 4-word addrs */
+
+/* CEH defines */
+#define CEH_NORMAL_CE  0x00000001	/* do not force CE ON */
+
+/* ISR register defines */
+#define ISR_NAND_READY        0x00000001
+#define ISR_CONTROLLER_READY  0x00000002
+#define ISR_ECC_READY         0x00000004
+#define ISR_DECODER_ERRORS(s) ((((s) >> 4) & 3)+1)
+#define ISR_DECODER_FAILURE   0x00000040
+#define ISR_DECODER_ERROR     0x00000008
+
+/* time-out for NAND chip / controller loops, in us */
+#define LPC32X_NAND_TIMEOUT 5000
+
+/*
+ * There is a single instance of the NAND MLC controller
+ */
+
+static struct lpc32xx_nand_mlc_registers __iomem *lpc32xx_nand_mlc_registers
+	= (struct lpc32xx_nand_mlc_registers __iomem *)MLC_NAND_BASE;
+
+#define clkdiv(v, w, o) (((1+(clk/v)) & w) << o)
+
+/**
+ * OOB data in each small page are 6 'free' then 10 ECC bytes.
+ * To make things easier, when reading large pages, the four pages'
+ * 'free' OOB bytes are grouped in the first 24 bytes of the OOB buffer,
+ * while the the four ECC bytes are groupe in its last 40 bytes.
+ *
+ * The struct below represents how free vs ecc oob bytes are stored
+ * in the buffer.
+ *
+ * Note: the OOB bytes contain the bad block marker at offsets 0 and 1.
+ */
+
+struct lpc32xx_oob {
+	struct {
+		uint8_t free_oob_bytes[6];
+	} free[4];
+	struct {
+		uint8_t ecc_oob_bytes[10];
+	} ecc[4];
+};
+
+/*
+ * Initialize the controller
+ */
+
+static void lpc32xx_nand_init(void)
+{
+	unsigned int clk;
+
+	/* Configure controller for no software write protection, x8 bus
+	   width, large block device, and 4 address words */
+
+	/* unlock controller registers with magic key */
+	writel(LOCK_PR_UNLOCK_KEY,
+	       &lpc32xx_nand_mlc_registers->lock_pr);
+
+	/* enable large blocks and large NANDs */
+	writel(ICR_LARGE_BLOCKS | ICR_ADDR4,
+	       &lpc32xx_nand_mlc_registers->icr);
+
+	/* Make sure MLC interrupts are disabled */
+	writel(0, &lpc32xx_nand_mlc_registers->irq_mr);
+
+	/* Normal chip enable operation */
+	writel(CEH_NORMAL_CE,
+	       &lpc32xx_nand_mlc_registers->ceh);
+
+	/* Setup NAND timing */
+	clk = get_hclk_clk_rate();
+
+	writel(
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_TCEA_DELAY, 0x03, 24) |
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_BUSY_DELAY, 0x1F, 19) |
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_NAND_TA,    0x07, 16) |
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_RD_HIGH,    0x0F, 12) |
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_RD_LOW,     0x0F, 8) |
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_WR_HIGH,    0x0F, 4) |
+		clkdiv(CONFIG_LPC32XX_NAND_MLC_WR_LOW,     0x0F, 0),
+		&lpc32xx_nand_mlc_registers->time_reg);
+}
+
+#if !defined(CONFIG_SPL_BUILD)
+
+/**
+ * lpc32xx_cmd_ctrl - write command to either cmd or data register
+ */
+
+static void lpc32xx_cmd_ctrl(struct mtd_info *mtd, int cmd,
+				   unsigned int ctrl)
+{
+	if (cmd == NAND_CMD_NONE)
+		return;
+
+	if (ctrl & NAND_CLE)
+		writeb(cmd & 0Xff, &lpc32xx_nand_mlc_registers->cmd);
+	else if (ctrl & NAND_ALE)
+		writeb(cmd & 0Xff, &lpc32xx_nand_mlc_registers->addr);
+}
+
+/**
+ * lpc32xx_read_byte - read a byte from the NAND
+ * @mtd:	MTD device structure
+ */
+
+static uint8_t lpc32xx_read_byte(struct mtd_info *mtd)
+{
+	return readb(&lpc32xx_nand_mlc_registers->data);
+}
+
+/**
+ * lpc32xx_dev_ready - test if NAND device (actually controller) is ready
+ * @mtd:	MTD device structure
+ * @mode:	mode to set the ECC HW to.
+ */
+
+static int lpc32xx_dev_ready(struct mtd_info *mtd)
+{
+	/* means *controller* ready for us */
+	int status = readl(&lpc32xx_nand_mlc_registers->isr);
+	return status & ISR_CONTROLLER_READY;
+}
+
+/**
+ * ECC layout -- this is needed whatever ECC mode we are using.
+ * In a 2KB (4*512B) page, R/S codes occupy 40 (4*10) bytes.
+ * To make U-Boot's life easier, we pack 'useable' OOB at the
+ * front and R/S ECC at the back.
+ */
+
+static struct nand_ecclayout lpc32xx_largepage_ecclayout = {
+	.eccbytes = 40,
+	.eccpos = {24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
+		   34, 35, 36, 37, 38, 39, 40, 41, 42, 43,
+		   44, 45, 46, 47, 48, 48, 50, 51, 52, 53,
+		   54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+		   },
+	.oobfree = {
+		/* bytes 0 and 1 are used for the bad block marker */
+		{
+			.offset = 2,
+			.length = 22
+		},
+	}
+};
+
+/**
+ * lpc32xx_read_page_hwecc - read in- and out-of-band data with ECC
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @buf: buffer to store read data
+ * @oob_required: caller requires OOB data read to chip->oob_poi
+ * @page: page number to read
+ *
+ * Use large block Auto Decode Read Mode(1) as described in User Manual
+ * section 8.6.2.1.
+ *
+ * The initial Read Mode and Read Start commands are sent by the caller.
+ *
+ * ECC will be false if out-of-band data has been updated since in-band
+ * data was initially written.
+ */
+
+static int lpc32xx_read_page_hwecc(struct mtd_info *mtd,
+	struct nand_chip *chip, uint8_t *buf, int oob_required,
+	int page)
+{
+	unsigned int i, status, timeout, err, max_bitflips = 0;
+	struct lpc32xx_oob *oob = (struct lpc32xx_oob *)chip->oob_poi;
+
+	/* go through all four small pages */
+	for (i = 0; i < 4; i++) {
+		/* start auto decode (reads 528 NAND bytes) */
+		writel(0, &lpc32xx_nand_mlc_registers->ecc_auto_dec_reg);
+		/* wait for controller to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_CONTROLLER_READY)
+				break;
+			udelay(1);
+		}
+		/* if decoder failed, return failure */
+		if (status & ISR_DECODER_FAILURE)
+			return -1;
+		/* keep count of maximum bitflips performed */
+		if (status & ISR_DECODER_ERROR) {
+			err = ISR_DECODER_ERRORS(status);
+			if (err > max_bitflips)
+				max_bitflips = err;
+		}
+		/* copy first 512 bytes into buffer */
+		memcpy(buf+512*i, lpc32xx_nand_mlc_registers->buff, 512);
+		/* copy next 6 bytes at front of OOB buffer */
+		memcpy(&oob->free[i], lpc32xx_nand_mlc_registers->buff, 6);
+		/* copy last 10 bytes (R/S ECC) at back of OOB buffer */
+		memcpy(&oob->ecc[i], lpc32xx_nand_mlc_registers->buff, 10);
+	}
+	return max_bitflips;
+}
+
+/**
+ * lpc32xx_read_page_raw - read raw (in-band, out-of-band and ECC) data
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @buf: buffer to store read data
+ * @oob_required: caller requires OOB data read to chip->oob_poi
+ * @page: page number to read
+ *
+ * Read NAND directly; can read pages with invalid ECC.
+ */
+
+static int lpc32xx_read_page_raw(struct mtd_info *mtd,
+	struct nand_chip *chip, uint8_t *buf, int oob_required,
+	int page)
+{
+	unsigned int i, status, timeout;
+	struct lpc32xx_oob *oob = (struct lpc32xx_oob *)chip->oob_poi;
+
+	/* when we get here we've already had the Read Mode(1) */
+
+	/* go through all four small pages */
+	for (i = 0; i < 4; i++) {
+		/* wait for NAND to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_NAND_READY)
+				break;
+			udelay(1);
+		}
+		/* if NAND stalled, return failure */
+		if (!(status & ISR_NAND_READY))
+			return -1;
+		/* copy first 512 bytes into buffer */
+		memcpy(buf+512*i, lpc32xx_nand_mlc_registers->data, 512);
+		/* copy next 6 bytes at front of OOB buffer */
+		memcpy(&oob->free[i], lpc32xx_nand_mlc_registers->data, 6);
+		/* copy last 10 bytes (R/S ECC) at back of OOB buffer */
+		memcpy(&oob->ecc[i], lpc32xx_nand_mlc_registers->data, 10);
+	}
+	return 0;
+}
+
+/**
+ * lpc32xx_read_oob - read out-of-band data
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @page: page number to read
+ *
+ * Read out-of-band data. User Manual section 8.6.4 suggests using Read
+ * Mode(3) which the controller will turn into a Read Mode(1) internally
+ * but nand_base.c will turn Mode(3) into Mode(0), so let's use Mode(0)
+ * directly.
+ *
+ * ECC covers in- and out-of-band data and was written when out-of-band
+ * data was blank. Therefore, if the out-of-band being read here is not
+ * blank, then the ECC will be false and the read will return bitflips,
+ * even in case of ECC failure where we will return 5 bitflips. The
+ * caller should be prepared to handle this.
+ */
+
+static int lpc32xx_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
+	int page)
+{
+	unsigned int i, status, timeout, err, max_bitflips = 0;
+	struct lpc32xx_oob *oob = (struct lpc32xx_oob *)chip->oob_poi;
+
+	/* No command was sent before calling read_oob() so send one */
+
+	chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
+
+	/* go through all four small pages */
+	for (i = 0; i < 4; i++) {
+		/* start auto decode (reads 528 NAND bytes) */
+		writel(0, &lpc32xx_nand_mlc_registers->ecc_auto_dec_reg);
+		/* wait for controller to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_CONTROLLER_READY)
+				break;
+			udelay(1);
+		}
+		/* if decoder failure, count 'one too many' bitflips */
+		if (status & ISR_DECODER_FAILURE)
+			max_bitflips = 5;
+		/* keep count of maximum bitflips performed */
+		if (status & ISR_DECODER_ERROR) {
+			err = ISR_DECODER_ERRORS(status);
+			if (err > max_bitflips)
+				max_bitflips = err;
+		}
+		/* set read pointer to OOB area */
+		writel(0, &lpc32xx_nand_mlc_registers->robp);
+		/* copy next 6 bytes at front of OOB buffer */
+		memcpy(&oob->free[i], lpc32xx_nand_mlc_registers->buff, 6);
+		/* copy next 10 bytes (R/S ECC) at back of OOB buffer */
+		memcpy(&oob->ecc[i], lpc32xx_nand_mlc_registers->buff, 10);
+	}
+	return max_bitflips;
+}
+
+/**
+ * lpc32xx_write_page_hwecc - write in- and out-of-band data with ECC
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @buf: data buffer
+ * @oob_required: must write chip->oob_poi to OOB
+ *
+ * Use large block Auto Encode as per User Manual section 8.6.4.
+ *
+ * The initial Write Serial Input and final Auto Program commands are
+ * sent by the caller.
+ */
+
+static int lpc32xx_write_page_hwecc(struct mtd_info *mtd,
+	struct nand_chip *chip, const uint8_t *buf, int oob_required)
+{
+	unsigned int i, status, timeout;
+	struct lpc32xx_oob *oob = (struct lpc32xx_oob *)chip->oob_poi;
+
+	/* when we get here we've already had the SEQIN */
+	for (i = 0; i < 4; i++) {
+		/* start encode (expects 518 writes to buff) */
+		writel(0, &lpc32xx_nand_mlc_registers->ecc_enc_reg);
+		/* copy first 512 bytes from buffer */
+		memcpy(&lpc32xx_nand_mlc_registers->buff, buf+512*i, 512);
+		/* copy next 6 bytes from OOB buffer -- excluding ECC */
+		memcpy(&lpc32xx_nand_mlc_registers->buff, &oob->free[i], 6);
+		/* wait for ECC to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_ECC_READY)
+				break;
+			udelay(1);
+		}
+		/* if ECC stalled, return failure */
+		if (!(status & ISR_ECC_READY))
+			return -1;
+		/* Trigger auto encode (writes 528 bytes to NAND) */
+		writel(0, &lpc32xx_nand_mlc_registers->ecc_auto_enc_reg);
+		/* wait for controller to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_CONTROLLER_READY)
+				break;
+			udelay(1);
+		}
+		/* if controller stalled, return error */
+		if (!(status & ISR_CONTROLLER_READY))
+			return -1;
+	}
+	return 0;
+}
+
+/**
+ * lpc32xx_write_page_raw - write raw (in-band, out-of-band and ECC) data
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @buf: buffer to store read data
+ * @oob_required: caller requires OOB data read to chip->oob_poi
+ * @page: page number to read
+ *
+ * Use large block write but without encode.
+ *
+ * The initial Write Serial Input and final Auto Program commands are
+ * sent by the caller.
+ *
+ * This function will write the full out-of-band data, including the
+ * ECC area. Therefore, it can write pages with valid *or* invalid ECC.
+ */
+
+static int lpc32xx_write_page_raw(struct mtd_info *mtd,
+	struct nand_chip *chip, const uint8_t *buf, int oob_required)
+{
+	unsigned int i;
+	struct lpc32xx_oob *oob = (struct lpc32xx_oob *)chip->oob_poi;
+
+	/* when we get here we've already had the Read Mode(1) */
+	for (i = 0; i < 4; i++) {
+		/* copy first 512 bytes from buffer */
+		memcpy(lpc32xx_nand_mlc_registers->buff, buf+512*i, 512);
+		/* copy next 6 bytes into OOB buffer -- excluding ECC */
+		memcpy(lpc32xx_nand_mlc_registers->buff, &oob->free[i], 6);
+		/* copy next 10 bytes into OOB buffer -- that is 'ECC' */
+		memcpy(lpc32xx_nand_mlc_registers->buff, &oob->ecc[i], 10);
+	}
+	return 0;
+}
+
+/**
+ * lpc32xx_write_oob - write out-of-band data
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @page: page number to read
+ *
+ * Since ECC covers in- and out-of-band data, writing out-of-band data
+ * with ECC will render the page ECC wrong -- or, if the page was blank,
+ * then it will produce a good ECC but a later in-band data write will
+ * render it wrong.
+ *
+ * Therefore, do not compute or write any ECC, and always return success.
+ *
+ * This implies that we do four writes, since non-ECC out-of-band data
+ * are not contiguous in a large page.
+ */
+
+static int lpc32xx_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
+	int page)
+{
+	/* update oob on all 4 subpages in sequence */
+	unsigned int i, status, timeout;
+	struct lpc32xx_oob *oob = (struct lpc32xx_oob *)chip->oob_poi;
+
+	for (i = 0; i < 4; i++) {
+		/* start data input */
+		chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x200+0x210*i, page);
+		/* copy 6 non-ECC out-of-band bytes directly into NAND */
+		memcpy(lpc32xx_nand_mlc_registers->data, &oob->free[i], 6);
+		/* program page */
+		chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+		/* wait for NAND to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_NAND_READY)
+				break;
+			udelay(1);
+		}
+		/* if NAND stalled, return error */
+		if (!(status & ISR_NAND_READY))
+			return -1;
+	}
+	return 0;
+}
+
+/**
+ * lpc32xx_waitfunc - wait until a command is done
+ * @mtd: MTD device structure
+ * @chip: NAND chip structure
+ *
+ * Wait for controller and FLASH to both be ready.
+ */
+
+static int lpc32xx_waitfunc(struct mtd_info *mtd, struct nand_chip *chip)
+{
+	int status;
+	unsigned int timeout;
+	/* wait until both controller and NAND are ready */
+	for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+		status = readl(&lpc32xx_nand_mlc_registers->isr);
+		if ((status & (ISR_CONTROLLER_READY || ISR_NAND_READY))
+		    == (ISR_CONTROLLER_READY || ISR_NAND_READY))
+			break;
+		udelay(1);
+	}
+	/* if controller or NAND stalled, return error */
+	if ((status & (ISR_CONTROLLER_READY || ISR_NAND_READY))
+	    != (ISR_CONTROLLER_READY || ISR_NAND_READY))
+		return -1;
+	/* write NAND status command */
+	writel(NAND_CMD_STATUS, &lpc32xx_nand_mlc_registers->cmd);
+	/* read back status and return it */
+	return readb(&lpc32xx_nand_mlc_registers->data);
+}
+
+/*
+ * We are self-initializing, so we need our own chip struct
+ */
+
+static struct nand_chip lpc32xx_chip;
+
+/*
+ * Initialize the controller
+ */
+
+void board_nand_init(void)
+{
+	/* we have only one device anyway */
+	struct mtd_info *mtd = &nand_info[0];
+	/* chip is struct nand_chip, and is now provided by the driver. */
+	mtd->priv = &lpc32xx_chip;
+	/* to store return status in case we need to print it */
+	int ret;
+
+	/* Set all BOARDSPECIFIC (actually core-specific) fields  */
+
+	lpc32xx_chip.IO_ADDR_R = &lpc32xx_nand_mlc_registers->buff;
+	lpc32xx_chip.IO_ADDR_W = &lpc32xx_nand_mlc_registers->buff;
+	lpc32xx_chip.cmd_ctrl = lpc32xx_cmd_ctrl;
+	/* do not set init_size: nand_base.c will read sizes from chip */
+	lpc32xx_chip.dev_ready = lpc32xx_dev_ready;
+	/* do not set setup_read_retry: this is NAND-chip-specific */
+	/* do not set chip_delay: we have dev_ready defined. */
+	lpc32xx_chip.options |= NAND_NO_SUBPAGE_WRITE;
+
+	/* Set needed ECC fields */
+
+	lpc32xx_chip.ecc.mode = NAND_ECC_HW;
+	lpc32xx_chip.ecc.layout = &lpc32xx_largepage_ecclayout;
+	lpc32xx_chip.ecc.size = 512;
+	lpc32xx_chip.ecc.bytes = 10;
+	lpc32xx_chip.ecc.strength = 4;
+	lpc32xx_chip.ecc.read_page = lpc32xx_read_page_hwecc;
+	lpc32xx_chip.ecc.read_page_raw = lpc32xx_read_page_raw;
+	lpc32xx_chip.ecc.write_page = lpc32xx_write_page_hwecc;
+	lpc32xx_chip.ecc.write_page_raw = lpc32xx_write_page_raw;
+	lpc32xx_chip.ecc.read_oob = lpc32xx_read_oob;
+	lpc32xx_chip.ecc.write_oob = lpc32xx_write_oob;
+	lpc32xx_chip.waitfunc = lpc32xx_waitfunc;
+
+	lpc32xx_chip.read_byte = lpc32xx_read_byte; /* FIXME: NEEDED? */
+
+	/* BBT options: read from last two pages */
+	lpc32xx_chip.bbt_options |= NAND_BBT_USE_FLASH | NAND_BBT_LASTBLOCK
+		| NAND_BBT_SCANLASTPAGE | NAND_BBT_SCAN2NDPAGE
+		| NAND_BBT_WRITE;
+
+	/* Initialize NAND interface */
+	lpc32xx_nand_init();
+
+	/* identify chip */
+	ret = nand_scan_ident(mtd, CONFIG_SYS_MAX_NAND_CHIPS, NULL);
+	if (ret) {
+		error("nand_scan_ident returned %i", ret);
+		return;
+	}
+
+	/* finish scanning the chip */
+	ret = nand_scan_tail(mtd);
+	if (ret) {
+		error("nand_scan_tail returned %i", ret);
+		return;
+	}
+
+	/* chip is good, register it */
+	ret = nand_register(0);
+	if (ret)
+		error("nand_register returned %i", ret);
+}
+
+#else /* defined(CONFIG_SPL_BUILD) */
+
+void nand_init(void)
+{
+	/* enable NAND controller */
+	lpc32xx_mlc_nand_init();
+	/* initialize NAND controller */
+	lpc32xx_nand_init();
+}
+
+void nand_deselect(void)
+{
+	/* nothing to do, but SPL requires this function */
+}
+
+static int read_single_page(uint8_t *dest, int page,
+	struct lpc32xx_oob *oob)
+{
+	int status, i, timeout, err, max_bitflips = 0;
+
+	/* enter read mode */
+	writel(NAND_CMD_READ0, &lpc32xx_nand_mlc_registers->cmd);
+	/* send column (lsb then MSB) and page (lsb to MSB) */
+	writel(0, &lpc32xx_nand_mlc_registers->addr);
+	writel(0, &lpc32xx_nand_mlc_registers->addr);
+	writel(page & 0xff, &lpc32xx_nand_mlc_registers->addr);
+	writel((page>>8) & 0xff, &lpc32xx_nand_mlc_registers->addr);
+	writel((page>>16) & 0xff, &lpc32xx_nand_mlc_registers->addr);
+	/* start reading */
+	writel(NAND_CMD_READSTART, &lpc32xx_nand_mlc_registers->cmd);
+
+	/* large page auto decode read */
+	for (i = 0; i < 4; i++) {
+		/* start auto decode (reads 528 NAND bytes) */
+		writel(0, &lpc32xx_nand_mlc_registers->ecc_auto_dec_reg);
+		/* wait for controller to return to ready state */
+		for (timeout = LPC32X_NAND_TIMEOUT; timeout; timeout--) {
+			status = readl(&lpc32xx_nand_mlc_registers->isr);
+			if (status & ISR_CONTROLLER_READY)
+				break;
+			udelay(1);
+		}
+		/* if controller stalled, return error */
+		if (!(status & ISR_CONTROLLER_READY))
+			return -1;
+		/* if decoder failure, return error */
+		if (status & ISR_DECODER_FAILURE)
+			return -1;
+		/* keep count of maximum bitflips performed */
+		if (status & ISR_DECODER_ERROR) {
+			err = ISR_DECODER_ERRORS(status);
+			if (err > max_bitflips)
+				max_bitflips = err;
+		}
+		/* copy first 512 bytes into buffer */
+		memcpy(dest+i*512, lpc32xx_nand_mlc_registers->buff, 512);
+		/* copy next 6 bytes bytes into OOB buffer */
+		memcpy(&oob->free[i], lpc32xx_nand_mlc_registers->buff, 6);
+	}
+	return max_bitflips;
+}
+
+/*
+ * Load U-Boot signed image.
+ * This loads an image from NAND, skipping bad blocks.
+ * A block is declared bad if at least one of its readable pages has
+ * a bad block marker in its OOB at position 0.
+ * If all pages ion a block are unreadable, the block is considered
+ * bad (i.e., assumed not to be part of the image) and skipped.
+ *
+ * IMPORTANT NOTE:
+ *
+ * If the first block of the image is fully unreadable, it will be
+ * ignored and skipped as if it had been marked bad. If it was not
+ * actually marked bad at the time of writing the image, the resulting
+ * image loaded will lack a header and magic number. It could thus be
+ * considered as a raw, headerless, image and SPL might erroneously
+ * jump into it.
+ *
+ * In order to avoid this risk, LPC32XX-based boards which use this
+ * driver MUST define CONFIG_SPL_PANIC_ON_RAW_IMAGE.
+ */
+
+#define BYTES_PER_PAGE 2048
+#define PAGES_PER_BLOCK 64
+#define BYTES_PER_BLOCK (BYTES_PER_PAGE * PAGES_PER_BLOCK)
+#define PAGES_PER_CHIP_MAX 524288
+
+int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
+{
+	int bytes_left = size;
+	int pages_left = DIV_ROUND_UP(size, BYTES_PER_PAGE);
+	int blocks_left = DIV_ROUND_UP(size, BYTES_PER_BLOCK);
+	int block = 0;
+	int page = offs / BYTES_PER_PAGE;
+	/* perform reads block by block */
+	while (blocks_left) {
+		/* compute first page number to read */
+		void *block_page_dst = dst;
+		/* read at most one block, possibly less */
+		int block_bytes_left = bytes_left;
+		if (block_bytes_left > BYTES_PER_BLOCK)
+			block_bytes_left = BYTES_PER_BLOCK;
+		/* keep track of good, failed, and "bad" pages */
+		int block_pages_good = 0;
+		int block_pages_bad = 0;
+		int block_pages_err = 0;
+		/* we shall read a full block of pages, maybe less */
+		int block_pages_left = pages_left;
+		if (block_pages_left > PAGES_PER_BLOCK)
+			block_pages_left = PAGES_PER_BLOCK;
+		int block_pages = block_pages_left;
+		int block_page = page;
+		/* while pages are left and the block is not known as bad */
+		while ((block_pages > 0) && (block_pages_bad == 0)) {
+			/* we will read OOB, too, for bad block markers */
+			struct lpc32xx_oob oob;
+			/* read page */
+			int res = read_single_page(block_page_dst, block_page,
+						   &oob);
+			/* count readable pages */
+			if (res >= 0) {
+				/* this page is good */
+				block_pages_good++;
+				/* this page is bad */
+				if ((oob.free[0].free_oob_bytes[0] != 0xff)
+				    | (oob.free[0].free_oob_bytes[1] != 0xff))
+					block_pages_bad++;
+			} else
+				/* count errors */
+				block_pages_err++;
+			/* we're done with this page */
+			block_page++;
+			block_page_dst += BYTES_PER_PAGE;
+			if (block_pages)
+				block_pages--;
+		}
+		/* a fully unreadable block is considered bad */
+		if (block_pages_good == 0)
+			block_pages_bad = block_pages_err;
+		/* errors are fatal only in good blocks */
+		if ((block_pages_err > 0) && (block_pages_bad == 0))
+			return -1;
+		/* we keep reads only of good blocks */
+		if (block_pages_bad == 0) {
+			dst += block_bytes_left;
+			bytes_left -= block_bytes_left;
+			pages_left -= block_pages_left;
+			blocks_left--;
+		}
+		/* good or bad, we're done with this block */
+		block++;
+		page += PAGES_PER_BLOCK;
+	}
+
+	/* report success */
+	return 0;
+}
+
+#endif /* CONFIG_SPL_BUILD */