[U-Boot] [PATCH v3 2/8] lpc32xx: mtd: nand: add MLC NAND controller

[Scott Wood]

On Thu, 2015-03-05 at 07:46 +0100, Albert ARIBAUD (3ADEV) wrote:
> diff --git a/drivers/mtd/nand/lpc32xx_nand_mlc.c b/drivers/mtd/nand/lpc32xx_nand_mlc.c
> new file mode 100644
> index 0000000..cb23972
> --- /dev/null
> +++ b/drivers/mtd/nand/lpc32xx_nand_mlc.c
> @@ -0,0 +1,589 @@
> +/*
> + * LPC32xx MLC NAND flash controller driver
> + *
> + * (C) Copyright 2014 3ADEV <http://3adev.com>
> + * Written by Albert ARIBAUD <albert.aribaud at 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.
> + */

When are you expecting later out-of-band writes?

> +static struct lpc32xx_nand_mlc_registers *lpc32xx_nand_mlc_registers
> +	= (struct lpc32xx_nand_mlc_registers *)MLC_NAND_BASE;

__iomem

> +				   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);
> +	else
> +		return;
> +}

That last return is superfluous.

> +/**
> + * 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 = {
> +		{
> +			.offset = 0,
> +			.length = 24
> +		},
> +	}
> +};

Is offset zero really free?  Where does the bad block marker go?

> +	for (i = 0; i < 4; i++) {
> +		/* start data input */
> +		oob[6*i] = ((0xfe << i) & 0xff);
> +		oob[6*i+5] = ((0x7f >> i) & 0xff);
> +		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+6*i, 6);

Lots of magic numbers...

> +		/* wait for NAND to return to ready state */
> +		while (!(readl(&lpc32xx_nand_mlc_registers->isr)
> +			& ISR_NAND_READY))
> +			;

Timeout?

> +	}
> +	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)
> +{
> +	/* FIXME: put a time-out here */
> +	int status;
> +	/* wait until both controller and NAND are ready */
> +	do {
> +		status = readl(&lpc32xx_nand_mlc_registers->isr);
> +	} while ((status & (ISR_CONTROLLER_READY || ISR_NAND_READY))
> +		 != (ISR_CONTROLLER_READY || ISR_NAND_READY));

Timeout?  Etc.

> +/*
> + * Initialize the controller
> + */
> +
> +int board_nand_init(struct nand_chip *nand)
> +{

It'd be nice if new NAND drivers used CONFIG_SYS_NAND_SELF_INIT.

> +
> +	/* BBT options: read from last two pages, don't write */
> +	nand->bbt_options |= NAND_BBT_USE_FLASH | NAND_BBT_LASTBLOCK
> +		| NAND_BBT_SCANLASTPAGE | NAND_BBT_SCAN2NDPAGE
> +		| NAND_BBT_WRITE;

Don't write?

> +#define LARGE_PAGE_SIZE 2048
> +
> +int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
> +{
> +	unsigned int page = offs / LARGE_PAGE_SIZE;
> +	unsigned int left = (size + LARGE_PAGE_SIZE - 1) / LARGE_PAGE_SIZE;

DIV_ROUND_UP()

> +	while (left) {
> +		if (read_single_page(dst, page) >= 0) {
> +			dst += LARGE_PAGE_SIZE;
> +			page++;
> +			left--;
> +		}
> +	}

No bad block skipping?

-Scott