[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 17:11, Marek Vasut 写道:
>> 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.
I think it is pellucid. I still don't think it is very important.

- LiuShuo

> M
>