RE: [EXT] Re: [PATCH v3 04/12] mtd: rawnand: introduce struct onfi_helper

["Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@micron.com>]

Hi Boris,

> > Create onfi_helper object. This is base to turn ONFI code to generic.
> >
> > Signed-off-by: Shivamurthy Shastri <sshivamurthy@micron.com>
> > ---
> >  include/linux/mtd/nand.h | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> >
> > diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
> > index 3cdf06cae8b6..645dde4c5797 100644
> > --- a/include/linux/mtd/nand.h
> > +++ b/include/linux/mtd/nand.h
> > @@ -11,6 +11,7 @@
> >  #define __LINUX_MTD_NAND_H
> >
> >  #include <linux/mtd/mtd.h>
> > +#include <linux/mtd/onfi.h>
> >
> >  /**
> >   * struct nand_memory_organization - Memory organization structure
> > @@ -157,6 +158,24 @@ struct nand_ops {
> >  	bool (*isbad)(struct nand_device *nand, const struct nand_pos
> *pos);
> >  };
> >
> > +/**
> > + * struct onfi_helper - ONFI helper functions that should be implemented
> by
> > + * specialized layers (raw NAND, SPI NAND, etc.)
> > + * @page: Page number for ONFI parameter table
> > + * @check_revision: Check ONFI revision number
> > + * @parameter_page_read: Function to read parameter pages
> > + * @init_intf_data: Initialize interface specific data or fixups
> > + */
> > +struct onfi_helper {
> > +	u8 page;
> > +	int (*check_revision)(struct nand_device *base,
> > +			      struct nand_onfi_params *p, int *onfi_version);
> > +	int (*parameter_page_read)(struct nand_device *base, u8 page,
> > +				   void *buf, unsigned int len);
> > +	int (*init_intf_data)(struct nand_device *base,
> > +			      struct nand_onfi_params *p);
> > +};
> > +
> >  /**
> >   * struct nand_device - NAND device
> >   * @mtd: MTD instance attached to the NAND device
> > @@ -165,6 +184,7 @@ struct nand_ops {
> >   * @rowconv: position to row address converter
> >   * @bbt: bad block table info
> >   * @ops: NAND operations attached to the NAND device
> > + * @helper: Helper functions to detect and initialize ONFI NAND
> >   *
> >   * Generic NAND object. Specialized NAND layers (raw NAND, SPI NAND,
> OneNAND)
> >   * should declare their own NAND object embedding a nand_device struct
> (that's
> > @@ -183,6 +203,7 @@ struct nand_device {
> >  	struct nand_row_converter rowconv;
> >  	struct nand_bbt bbt;
> >  	const struct nand_ops *ops;
> > +	struct onfi_helper helper;
> 
> Sorry, but I don't think that's the right solution. When I said we
> should have ONFI code shared I was thinking about the code that parses
> the ONFI struct/data to extract nand_memory_organization bits or other
> generic info, not something that would abstract how to retrieve the
> ONFI param page. Clearly, the generic NAND layer is not supposed to
> handle such protocol/low-level details.
> 

In that case, I am thinking to design as follows, which splits into generic independent code.
Let me know, if you have any concerns or inputs.

I will parsing code from nand_onfi_detect function and move it to mtd/nand/onfi.c.
Also, I will move functions like sanitize_string, nand_bit_wise_majority, onfi_crc16, and 
any other generic info to mtd/nand/onfi.c.

Thanks,
Shiva

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