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

[Marek Vasut]

> 于 2011年12月09日 16:27, Marek Vasut 写道:
> >> 于 2011年12月09日 00:37, Marek Vasut 写道:
> >>>> 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 at freescale.com>
> >>>> Signed-off-by: Liu Shuo<b35362 at 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.

M