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

[LiuShuo]

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);

-Liu Shuo
> M
>