[U-Boot] [PATCH 5/5] mtd/nand: workaround for Freescale FCM to support 4k pagesize Nand chip

[Marek Vasut <marek.vasut@gmail.com>]

> ? 2011?12?09? 17:11, Marek Vasut ??:
> >> ? 2011?12?09? 16:27, Marek Vasut ??:
> >>>> ? 2011?12?09? 00:37, Marek Vasut ??:
> >>>>>> Freescale FCM controller has a 2K size limitation of buffer RAM. In
> >>>>>> order to support the Nand flash chip whose page size is larger than
> >>>>>> 2K bytes, we read/write 2k data repeatedly by issuing
> >>>>>> FIR_OP_RB/FIR_OP_WB and save them to a large buffer.
> >>>>>> 
> >>>>>> Signed-off-by: Shengzhou Liu<Shengzhou.Liu@freescale.com>
> >>>>>> Signed-off-by: Liu Shuo<b35362@freescale.com>
> >>>>>> ---
> >>>>>> 
> >>>>>>     drivers/mtd/nand/fsl_elbc_nand.c |  279
> >>>>>> 
> >>>>>> +++++++++++++++++++++++++++++++++---- 1 files changed, 248
> >>>>>> insertions(+), 31 deletions(-)
> >>>>>> 
> >>>>>> diff --git a/drivers/mtd/nand/fsl_elbc_nand.c
> >>>>>> b/drivers/mtd/nand/fsl_elbc_nand.c index 52362b1..3983c8c 100644
> >>>>>> --- a/drivers/mtd/nand/fsl_elbc_nand.c
> >>>>>> +++ b/drivers/mtd/nand/fsl_elbc_nand.c
> >>>>>> @@ -64,7 +64,6 @@ struct fsl_elbc_mtd {
> >>>>>> 
> >>>>>>     	struct device *dev;
> >>>>>>     	int bank;               /* Chip select bank number           */
> >>>>>>     	u8 __iomem *vbase;      /* Chip select base virtual address  */
> >>>>>> 
> >>>>>> -	int page_size;          /* NAND page size (0=512, 1=2048)    */
> >>>>>> 
> >>>>>>     	unsigned int fmr;       /* FCM Flash Mode Register value     */
> >>>>>>     
> >>>>>>     };
> >>>>>> 
> >>>>>> @@ -85,6 +84,8 @@ struct fsl_elbc_ctrl {
> >>>>>> 
> >>>>>>     	unsigned int mdr;        /* UPM/FCM Data Register value
> >>>>>>     	*/ unsigned int use_mdr;    /* Non zero if the MDR is to be set
> >>>>>>     	
> >>>>>>     	   */ unsigned int oob;        /* Non zero if operating on OOB
> >>>>>>     	
> >>>>>>     	data     */
> >>>>>> 
> >>>>>> +	char *buffer;            /* just used when pagesize is greater
> > 
> > */
> > 
> >>>>> Start sentence with capital letter
> >>>>> 
> >>>>>> +				 /* than FCM RAM 2K limitation
> > 
> > */
> > 
> >>>>>>     };
> >>>>>>     
> >>>>>>     /* These map to the positions used by the FCM hardware ECC
> >>>>>>     generator */
> >>>>>> 
> >>>>>> @@ -159,6 +160,44 @@ static struct nand_bbt_descr bbt_mirror_descr =
> >>>>>> {
> >>>>>> 
> >>>>>>     	.pattern = mirror_pattern,
> >>>>>>     
> >>>>>>     };
> >>>>>> 
> >>>>>> +static void io_to_buffer(struct mtd_info *mtd, int subpage, int
> >>>>>> oob) +{
> >>>>>> +	struct nand_chip *chip = mtd->priv;
> >>>>>> +	struct fsl_elbc_mtd *priv = chip->priv;
> >>>>>> +	struct fsl_elbc_ctrl *ctrl = priv->ctrl;
> >>>>>> +	void *src, *dst;
> >>>>>> +	int len = (oob ? 64 : 2048);
> >>>>> 
> >>>>> No parenthesis ...
> >>>>> 
> >>>>>> +
> >>>>>> +	/* for emulating 4096+ bytes NAND using 2048-byte FCM RAM */
> >>>>>> +	if (oob)
> >>>>>> +		dst = ctrl->buffer + mtd->writesize + subpage * 64;
> >>>>>> +	else
> >>>>>> +		dst = ctrl->buffer + subpage * 2048;
> >>>>> 
> >>>>> subpage * len ?
> >>>> 
> >>>> dst = ctrl->buffer + (oob ? mtd->writesize : 0) + subpage * len ?
> >>>> Is this important ? I think it is ok.
> >>> 
> >>> dst = ctrl->buffer + subpage * len;
> >>> 
> >>> if (oob)
> >>> 
> >>> 	dst += mtd->writesize;
> >>> 
> >>> it's important, this code looks like mess. You introduce len and don't
> >>> use it anywhere then ?
> >> 
> >> memcpy_fromio(dst, src, len);
> > 
> > Ok, why not use it consistently then.
> 
> I think it is pellucid. I still don't think it is very important.

Ok, enough of this stuff, apparently I'm loosing time here. Let's see what 
others think.

M