Re: Re: [PATCH v3 2/3] mtd: spi-nor: add 4bit block protection support

[Jungseung Lee <js07.lee@samsung.com>]

Hi, Michael

2020-01-28 (화), 13:29 +0100, Michael Walle:
> Am 2020-01-28 12:01, schrieb Jungseung Lee:
> > Hi, Michael
> > 
> > 2020-01-23 (Thu), 10:31 +0100, Michael Walle:
> > > Am 2020-01-23 09:53, schrieb Jungseung Lee:
> > > > Hi, Michael
> > > > 
> > > > 2020-01-23 (Thu), 09:10 +0100, Michael Walle:
> > > > > Hi Jungseung,
> > > > > 
> > > > > Am 2020-01-23 07:22, schrieb Jungseung Lee:
> > > > > > Hi, Michael
> > > > > > 
> > > > > > 2020-01-22 (Wed), 20:36 +0100, Michael Walle:
> > > > > > > Hi,
> > > > > > > 
> > > > > > > > Currently, we are supporting block protection only for
> > > > > > > > flash chips with 3 block protection bits in the SR
> > > > > > > > register.
> > > > > > > > This patch enables block protection support for some
> > > > > > > > flash
> > > > > > > > with
> > > > > > > > 4 block protection bits(bp0-3).
> > > > > > > > 
> > > > > > > > Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
> > > > > > > > ---
> > > > > > > > v3 :
> > > > > > > >   Fix wrong ofs calculation on v2 patch
> > > > > > > > v2 :
> > > > > > > >   Add sample table portion about 4bit block protection
> > > > > > > > on
> > > > > > > > the
> > > > > > > > comment
> > > > > > > >   Trivial coding style change
> > > > > > > > 
> > > > > > > >  drivers/mtd/spi-nor/spi-nor.c | 127
> > > > > > > > +++++++++++++++++++++++++++++-
> > > > > > > > ----
> > > > > > > >  include/linux/mtd/spi-nor.h   |   8 +++
> > > > > > > >  2 files changed, 119 insertions(+), 16 deletions(-)
> > > > > > > > 
> > > > > > > > diff --git a/drivers/mtd/spi-nor/spi-nor.c
> > > > > > > > b/drivers/mtd/spi-
> > > > > > > > nor/spi-nor.c
> > > > > > > > index e3da6a8654a8..7e8af6c4fdfa 100644
> > > > > > > > --- a/drivers/mtd/spi-nor/spi-nor.c
> > > > > > > > +++ b/drivers/mtd/spi-nor/spi-nor.c
> > > > > > > > @@ -238,6 +238,14 @@ struct flash_info {
> > > > > > > >  					 * status
> > > > > > > > register.
> > > > > > > > Must be
> > > > > > > > used with
> > > > > > > >  					 *
> > > > > > > > SPI_NOR_HAS_TB.
> > > > > > > >  					 */
> > > > > > > > +#define SPI_NOR_HAS_BP3		BIT(17)	/*
> > > > > > > > +					 * Flash SR has
> > > > > > > > 4 bit
> > > > > > > > fields
> > > > > > > > (BP0-3)
> > > > > > > > +					 * for block
> > > > > > > > protection.
> > > > > > > > +					 */
> > > > > > > > +#define SPI_NOR_BP3_SR_BIT6	BIT(18)	/*
> > > > > > > > +					 * BP3 is bit 6
> > > > > > > > of
> > > > > > > > status
> > > > > > > > register.
> > > > > > > > +					 * Must be used
> > > > > > > > with
> > > > > > > > SPI_NOR_HAS_BP3.
> > > > > > > > +					 */
> > > > > > > > 
> > > > > > > >  	/* Part specific fixup hooks. */
> > > > > > > >  	const struct spi_nor_fixups *fixups;
> > > > > > > > @@ -1767,23 +1775,47 @@ static void
> > > > > > > > stm_get_locked_range(struct
> > > > > > > > spi_nor *nor, u8 sr, loff_t *ofs,
> > > > > > > >  	struct mtd_info *mtd = &nor->mtd;
> > > > > > > >  	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
> > > > > > > >  	u8 tb_mask = SR_TB_BIT5;
> > > > > > > > -	int pow;
> > > > > > > > +	u8 bp;
> > > > > > > > +	int pow = 0;
> > > > > > > > 
> > > > > > > >  	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> > > > > > > >  		tb_mask = SR_TB_BIT6;
> > > > > > > > 
> > > > > > > > -	if (!(sr & mask)) {
> > > > > > > > -		/* No protection */
> > > > > > > > -		*ofs = 0;
> > > > > > > > -		*len = 0;
> > > > > > > > +	if (nor->flags & SNOR_F_HAS_SR_BP3) {
> > > > > > > > +		u8 tmp;
> > > > > > > > +
> > > > > > > > +		if (nor->flags &
> > > > > > > > SNOR_F_HAS_SR_BP3_BIT6)
> > > > > > > > +			tmp = sr & (mask |
> > > > > > > > SR_BP3_BIT6);
> > > > > > > > +		else
> > > > > > > > +			tmp = sr & (mask |
> > > > > > > > SR_BP3_BIT5);
> > > > > > > > +
> > > > > > > > +		if (tmp & SR_BP3_BIT6)
> > > > > > > > +			tmp = (tmp & ~BIT(6)) | BIT(5);
> > > > > > > > +
> > > > > > > > +		bp = tmp >> SR_BP_SHIFT;
> > > > > > > > +		if (!bp) {
> > > > > > > > +			*ofs = 0;
> > > > > > > > +			*len = 0;
> > > > > > > > +			return;
> > > > > > > > +		}
> > > > > > > > +		if (bp <= ilog2(nor->n_sectors))
> > > > > > > > +			pow = ilog2(nor->n_sectors) + 1
> > > > > > > > - bp;
> > > > > > > >  	} else {
> > > > > > > > -		pow = ((sr & mask) ^ mask) >>
> > > > > > > > SR_BP_SHIFT;
> > > > > > > > -		*len = mtd->size >> pow;
> > > > > > > > -		if (nor->flags & SNOR_F_HAS_SR_TB && sr
> > > > > > > > &
> > > > > > > > tb_mask)
> > > > > > > > +		bp = (sr & mask) >> SR_BP_SHIFT;
> > > > > > > > +		if (!bp) {
> > > > > > > >  			*ofs = 0;
> > > > > > > > -		else
> > > > > > > > -			*ofs = mtd->size - *len;
> > > > > > > > +			*len = 0;
> > > > > > > > +			return;
> > > > > > > > +		}
> > > > > > > > +		pow = bp ^ (mask >> SR_BP_SHIFT);
> > > > > > > >  	}
> > > > > > > > +
> > > > > > > > +	*len = mtd->size >> pow;
> > > > > > > > +
> > > > > > > > +	if (nor->flags & SNOR_F_HAS_SR_TB && sr &
> > > > > > > > tb_mask)
> > > > > > > > +		*ofs = 0;
> > > > > > > > +	else
> > > > > > > > +		*ofs = mtd->size - *len;
> > > > > > > >  }
> > > > > > > > 
> > > > > > > >  /*
> > > > > > > > @@ -1823,7 +1855,7 @@ static int
> > > > > > > > stm_is_unlocked_sr(struct
> > > > > > > > spi_nor
> > > > > > > > *nor, loff_t ofs, uint64_t len,
> > > > > > > > 
> > > > > > > >  /*
> > > > > > > >   * Lock a region of the flash. Compatible with ST
> > > > > > > > Micro
> > > > > > > > and
> > > > > > > > similar flash.
> > > > > > > > - * Supports the block protection bits BP{0,1,2} in the
> > > > > > > > status
> > > > > > > > register
> > > > > > > > + * Supports the block protection bits BP{0,1,2,3} in
> > > > > > > > the
> > > > > > > > status
> > > > > > > > register
> > > > > > > >   * (SR). Does not support these features found in
> > > > > > > > newer SR
> > > > > > > > bitfields:
> > > > > > > >   *   - SEC: sector/block protect - only handle SEC=0
> > > > > > > > (block
> > > > > > > > protect)
> > > > > > > >   *   - CMP: complement protect - only support CMP=0
> > > > > > > > (range
> > > > > > > > is
> > > > > > > > not
> > > > > > > > complemented)
> > > > > > > > @@ -1831,7 +1863,7 @@ static int
> > > > > > > > stm_is_unlocked_sr(struct
> > > > > > > > spi_nor
> > > > > > > > *nor, loff_t ofs, uint64_t len,
> > > > > > > >   * Support for the following is provided conditionally
> > > > > > > > for
> > > > > > > > some
> > > > > > > > flash:
> > > > > > > >   *   - TB: top/bottom protect
> > > > > > > >   *
> > > > > > > > - * Sample table portion for 8MB flash (Winbond
> > > > > > > > w25q64fw):
> > > > > > > > + * Sample table portion for 8MB flash (Winbond
> > > > > > > > w25q64fw /
> > > > > > > > BP0-
> > > > > > > > 2):
> > > > > > > >   *
> > > > > > > >   *   SEC  |  TB   |  BP2  |  BP1  |  BP0  |  Prot
> > > > > > > > Length  |
> > > > > > > > Protected Portion
> > > > > > > >   *  ------------------------------------------------
> > > > > > > > ----
> > > > > > > > ----
> > > > > > > > ----
> > > > > > > > --------------
> > > > > > > > @@ -1851,6 +1883,32 @@ static int
> > > > > > > > stm_is_unlocked_sr(struct
> > > > > > > > spi_nor
> > > > > > > > *nor, loff_t ofs, uint64_t len,
> > > > > > > >   *    0   |   1   |   1   |   0   |   1   |  2
> > > > > > > > MB         |
> > > > > > > > Lower
> > > > > > > > 1/4
> > > > > > > >   *    0   |   1   |   1   |   1   |   0   |  4
> > > > > > > > MB         |
> > > > > > > > Lower
> > > > > > > > 1/2
> > > > > > > >   *
> > > > > > > > + * Sample table portion for 64MB flash (Micron
> > > > > > > > n25q512ax3
> > > > > > > > /
> > > > > > > > BP0-
> > > > > > > > 3):
> > > > > > > > + *
> > > > > > > > + *   TB   |  BP3  |  BP2  |  BP1  |  BP0  |  Prot
> > > > > > > > Length  |
> > > > > > > > Protected Portion
> > > > > > > > + *  ------------------------------------------------
> > > > > > > > ----
> > > > > > > > ----
> > > > > > > > ----
> > > > > > > > --------------
> > > > > > > > +
> > > > > > > > *    0   |   0   |   0   |   0   |   0   |  NONE       
> > > > > > > >   |
> > > > > > > > NONE
> > > > > > > > + *    0   |   0   |   0   |   0   |   1   |   64
> > > > > > > > KB       |
> > > > > > > > Upper
> > > > > > > > 1/1024
> > > > > > > > + *    0   |   0   |   0   |   1   |   0   |  128
> > > > > > > > KB       |
> > > > > > > > Upper
> > > > > > > > 1/512
> > > > > > > > + *    0   |   0   |   0   |   1   |   1   |  256
> > > > > > > > KB       |
> > > > > > > > Upper
> > > > > > > > 1/256
> > > > > > > > + *   ...
> > > > > > > > + *    0   |   1   |   0   |   0   |   1   |  16
> > > > > > > > MB        |
> > > > > > > > Upper
> > > > > > > > 1/4
> > > > > > > > + *    0   |   1   |   0   |   1   |   0   |  32
> > > > > > > > MB        |
> > > > > > > > Upper
> > > > > > > > 1/2
> > > > > > > > + *    0   |   1   |   0   |   1   |   1   |  64
> > > > > > > > MB        |
> > > > > > > > ALL
> > > > > > > > + *    0   |   1   |   1   |   0   |   0   |  64
> > > > > > > > MB        |
> > > > > > > > ALL
> > > > > > > > + *   ...
> > > > > > > > + *  ------|-------|-------|-------|-------|-----------
> > > > > > > > ----
> > > > > > > > > ---
> > > > > > > > 
> > > > > > > > ----
> > > > > > > > ------------
> > > > > > > > +
> > > > > > > > *    1   |   0   |   0   |   0   |   0   |   NONE      
> > > > > > > >   |
> > > > > > > > NONE
> > > > > > > > + *    1   |   0   |   0   |   0   |   1   |   64
> > > > > > > > KB       |
> > > > > > > > Lower
> > > > > > > > 1/1024
> > > > > > > > + *    1   |   0   |   0   |   1   |   0   |  128
> > > > > > > > KB       |
> > > > > > > > Lower
> > > > > > > > 1/512
> > > > > > > > + *    1   |   0   |   0   |   1   |   1   |  256
> > > > > > > > KB       |
> > > > > > > > Lower
> > > > > > > > 1/256
> > > > > > > > + *   ...
> > > > > > > > + *    1   |   1   |   0   |   0   |   1   |  16
> > > > > > > > MB        |
> > > > > > > > Lower
> > > > > > > > 1/4
> > > > > > > > + *    1   |   1   |   0   |   1   |   0   |  32
> > > > > > > > MB        |
> > > > > > > > Lower
> > > > > > > > 1/2
> > > > > > > > + *    1   |   1   |   0   |   1   |   1   |  64
> > > > > > > > MB        |
> > > > > > > > ALL
> > > > > > > > + *    1   |   1   |   1   |   0   |   0   |  64
> > > > > > > > MB        |
> > > > > > > > ALL
> > > > > > > > + *   ...
> > > > > > > > + *
> > > > > > > >   * Returns negative on errors, 0 on success.
> > > > > > > >   */
> > > > > > > >  static int stm_lock(struct spi_nor *nor, loff_t ofs,
> > > > > > > > uint64_t
> > > > > > > > len)
> > > > > > > > @@ -1898,6 +1956,12 @@ static int stm_lock(struct
> > > > > > > > spi_nor
> > > > > > > > *nor,
> > > > > > > > loff_t ofs, uint64_t len)
> > > > > > > >  	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> > > > > > > >  		tb_mask = SR_TB_BIT6;
> > > > > > > > 
> > > > > > > > +	if (nor->flags & SNOR_F_HAS_SR_BP3) {
> > > > > > > > +		if (nor->flags &
> > > > > > > > SNOR_F_HAS_SR_BP3_BIT6)
> > > > > > > > +			mask = mask | SR_BP3_BIT6;
> > > > > > > > +		else
> > > > > > > > +			mask = mask | SR_BP3_BIT5;
> > > > > > > > +	}
> > > > > > > >  	/*
> > > > > > > >  	 * Need smallest pow such that:
> > > > > > > >  	 *
> > > > > > > > @@ -1908,7 +1972,17 @@ static int stm_lock(struct
> > > > > > > > spi_nor
> > > > > > > > *nor,
> > > > > > > > loff_t ofs, uint64_t len)
> > > > > > > >  	 *   pow = ceil(log2(size / len)) = log2(size)
> > > > > > > > -
> > > > > > > > floor(log2(len))
> > > > > > > >  	 */
> > > > > > > >  	pow = ilog2(mtd->size) - ilog2(lock_len);
> > > > > > > > -	val = mask - (pow << SR_BP_SHIFT);
> > > > > > > > +
> > > > > > > > +	if (nor->flags & SNOR_F_HAS_SR_BP3) {
> > > > > > > > +		val = ilog2(nor->n_sectors) + 1 - pow;
> > > > > > > 
> > > > > > > Why do you use a new calculation here? As far as I can
> > > > > > > see,
> > > > > > > the
> > > > > > > method is
> > > > > > > the same except that is has one bit more. That also
> > > > > > > raises
> > > > > > > the
> > > > > > > question why
> > > > > > > n_sectors is now needed?
> > > > > > > 
> > > > > > > Can't we just initialize the mask with
> > > > > > > 
> > > > > > > mask = SR_BP2 | SR_BP1 | SR_BP0;
> > > > > > > if (nor->flags & SNOR_F_HAS_SR_BP3)
> > > > > > >     mask |= SR_BP3_BIT5;
> > > > > > > 
> > > > > > > do the calculation and checks and then move the
> > > > > > > SR_BP3_BIT5
> > > > > > > to
> > > > > > > SR_BP3_BIT6
> > > > > > > if SNOR_F_HAS_SR_BP3_BIT6 is set.
> > > > > > > 
> > > > > > 
> > > > > > For most of flashes that supporting BP0-2, the smallest
> > > > > > protected
> > > > > > portion is fixed as 1/64
> > > > > > and it can be properly handled by existing
> > > > > > calculation. (Actually it's not fully generic, see flashes
> > > > > > like
> > > > > > w25q40bw or m25p80. Of course, it doesn't have
> > > > > > SPI_NOR_HAS_LOCK
> > > > > > flag
> > > > > > even though it has BP0-2 bit in SR)
> > > > > 
> > > > > No. The rules are always the same wether there are three or
> > > > > four
> > > > > BP
> > > > > bits (the example in stm_lock() has not enough information on
> > > > > this):
> > > > > 
> > > > > (1) the first setting (besides 0) protects one sector. The
> > > > > second
> > > > >      protects 2, the third 4 and so on. eg 2^N
> > > > > (2) the last setting is _always_ protect all, just like the
> > > > > '0'
> > > > > setting
> > > > >      is always protect none.
> > > > > (3) if there is an overflow because there are no more free
> > > > > slots
> > > > > for
> > > > >      further settings (for 3 bits with flashes > 32MBit, for
> > > > > 4
> > > > >      bits if should be flashes > 16GBit), the first entry
> > > > > will be
> > > > >      discarded (eg the very first is the "just one sector"
> > > > > entry).
> > > > > 
> > > > > This is true for all flashes which uses this kind of setting,
> > > > > have a
> > > > > look at the m25p80 or w25q40bw, these are no exception. It is
> > > > > just
> > > > > the
> > > > > notation "lower 1/64" which is only true for flashes which
> > > > > either
> > > > > overflows in (3) or fill all entries (eg. with 3bits that
> > > > > would
> > > > > be
> > > > > the
> > > > > 32Mbit version).
> > > > > 
> > > > 
> > > > Looks like you noticed that we need new calculation method that
> > > > would
> > > > be based on n_sectors :).
> > > 
> > > No it will work without that (if I'm not mistaken). Give me some
> > > time
> > > and I'll post a patch.
> > 
> > No, it must be based on n_sectors. To make 4bit block protection
> > more
> > generic, the lock sector size must NOT fixed as 64KB (as can be
> > checked
> > from your patch). See "mt35xu02g" and check the protected area and
> > number of sectors from it's datasheet.
> 
> There is no public datasheet as far as I can see. And yes, actually
> n_sectors is my "mtd-size / sector_size". But I don't see how
> n_sectors
> would help if the sector size changes.
> 
> > The rule you mentioned "the first setting (besides 0) protects one
> > sector" is alawys true for *4bit* block protection. That's why I
> > choose
> > n_sectors for new calculation.
> 
> And how does flashes behave once all the free slots are full? It was
> the
> same with the 3bit flashes, they only overflowed with "newer"/bigger
> flashes.
> 
> 
> > > 
> > > > Rule (1) is NOT true for some flashes
> > > > supporting BP0-2 and that's why I said that smallest protected
> > > > portion
> > > > is fixed as '1/64' for these flashes.
> > > 
> > > No, you have to apply rule (3). (1) is only the starting point.
> > > It
> > > is
> > > kind
> > > of a sliding window.
> > > 
> > > > See this one.
> > > > 
> > > > W25Q20EW	256KB	1/4 ... = 64KB		BP2
> > > > W25Q128JV	16MB	1/64 ... = 256KB	BP2 <--
> > > > S25FL132K	4MB	1/64 ... = 64KB		BP2 <--
> > > > S25FL164K	8MB
> > > > 1/64 ... = 128KB	BP2 <--
> > > 
> > > All these flashes need (3) to be applied, thus (1) doesn't apply
> > > anymore.
> > > 
> > > Let me give you an example for the 64MBit case, the settings
> > > would
> > > be:
> > > 
> > > 0 sectors (corresponds to protect none)
> > > 1 sector
> > > 2 sectors
> > > 4 sectors
> > > 8 sectors
> > > 16 sectors
> > > 32 sectors
> > > 64 sectors
> > > 128 sectors (corresponds to protect all)
> > > 
> > > Unfortunately, we have only 8 slots (because 3 BP bits),
> > > therefore
> > > we
> > > have
> > > to discard some setting. According to rule (2) 0 is always
> > > "protect
> > > none"
> > > and 7 is always "protect all". Thus we have 6 settings left.
> > > According
> > > to
> > > rule (3) we discard the first ones. In this case, this is the "1
> > > sector"
> > > setting. Thus we end up with the following possible settings:
> > > 
> > > 0 sectors (corresponds to protect none)
> > > 2 sectors
> > > 4 sectors
> > > 8 sectors
> > > 16 sectors
> > > 32 sectors
> > > 64 sectors
> > > 128 sectors (corresponds to protect all)
> > > 
> > > If you have a 128Mbit flash, the next setting that would be
> > > discarded
> > > is
> > > "2 sectors". Thus it would start with:
> > > 
> > > 0 sectors (corresponds to protect none)
> > > 4 sectors
> > > [..]
> > > 256 sectors (corresponds to protect all)
> > > 
> > > 
> > > Another example W25Q20EW, following possible settings:
> > > 
> > > 0 sectors (corresponds to protect none)
> > > 1 sector
> > > 2 sectors
> > > 4 sectors (corresponds to protect all)
> > > 
> > > We now have less settings then our 8 possible slots. So this is
> > > where
> > > rule (1) applies, because according to that the "1 sector"
> > > setting is
> > > the first possible setting besides 0.
> > > 
> > > And this also applies to the 4 bit protection bits.
> > > 
> > > 
> > > 
> > > > W25Q256JV	32MB	1/512 ... =
> > > > 64KB	BP3
> > > > S25FL128L	16MB	1/256 ... = 64KB	BP3
> > > > S25FL256L	32MB	1/512 ... = 64KB	BP3
> > > > 
> > > > In current BP implementation, block protection is just working
> > > > for
> > > > some
> > > > flashes that has smallest protected portion as '1/64'.
> > > 
> > > No its currently working for all except flashes smaller than
> > > 32Mbit.
> > 
> > No. Not working for flashes supporting 4bit block protection.
> > 
> > > Applied to the 4 bits, this would mean "it works for all except
> > > flashes
> > > smaller than 8Gbit" which are practially all. As I said, this is
> > > a
> > > bug
> > > and once this bug is fixed, there should be no difference between
> > > 3
> > > and 4 bits.
> > > 
> > > -michael
> > > 
> > 
> > The exact fact is that locks operate in two different ways
> > according to
> > flash model.
> > 
> > (1) the smallest protected portion is fixed.
> > 	for BP0-2 : 1/64
> > 	for BP0-1 : 1/4
> 
> As mentioned earlier, the ratio nomenclature is missleading and only 
> valid if the table is completely filled up.
> 
> Take a flash with 128kB and three BP bits (or even only two BP
> bits). 
> The
> smallest portion will be 64kB (which is one sector and not 1/64).
> 
> Thus the smallest portion is always one sector, unless the table is
> overflowing, then the smallest will settle to 1/4 (for two), 1/64
> (for 
> three)
> and 1/16384 (for four bits).
> 
> > (2) the smallest protected portion is inversely propotional with
> > number
> > of sectors.
> > 
> > For the flashes supporting 3bit block protection, (1) and (2) are
> > mixed
> > and used. But all the flashes supporting 4bit block protection
> > listed
> > on spi-nor.c, only (2) is used.
> 
> It is not mixed it just depends on the flash size (and the number of
> protection bits).
> 

It is mixed. Let's compare "en25qh128" from EON with "w25q128jv" from
Winbond. They have the same capacity(128MBit) and also supporting 3bit
block protection. (Note that the named BP3 bit of "en25qh128" is
working exactly same with T/B bit.)

"en25qh128" is following (2) and "w25q128jv" is following (1). It seems
impossible to distinguish them by the flash size or the number of
protection bits. 

I also still have no idea how your three rules are applicable for 2bit
block protection (bp0-1).

> > Each method requires each formula. I have no idea how to handle it
> > with
> > one formula (probably adding number of exceptional handling?)
> > without
> > any sectional flag. "w25q128jv(bp0-2)" is following (1) and
> > "n25q128a(bp0-3)" is following (2).
> 
> Well one uses three BPs the other four, and they all follow the
> three 
> rules
> above. Did you try my patch? Because I've (at least in userspace)
> tested
> it with 4 bits and got the correct results.
> 
> And yes, its actually two different formulas, but not for 3 and 4
> bits like in your patch. 

The title of my patch is "add 4bit block protection support". I just
let 3bit block protection as it is, I've implemented something what I
could check. As I mentioned, for all the flashes supporting 4bit block
protection only (2) is used and this patch has been implemented based
on this fact.

> It is rather one formula (A) for flashes which don't 
> exhaust
> the BP bits (eg. for 3 bits this would be flashes <= 16Mbit and for
> 4 
> bits
> this would be for flashes <=8Gbit) and one (B) for the flashes where 
> every
> BP bit combination is used. What is at the moment in the kernel is
> the
> second one, thus it will fail for flashes <= 16Mbit and 3 BP bits;
> and 
> it
> also fails for all flashes with 4 bits. My patch does a fixup on (B)
> to
> match the results of (A), because doing this is less invasive; and as
> mentioned in the patch annex, might also be rewritten for a better
> understanding.

I've never seen spi flashes greater than 8Gbit (maybe you also), so I
am not sure whether the three rules are applicable to 4 bit block
protection. Even the three rules doesn't seem to be general enough for
3bit or 2bit block protection.

> 
> 
> -michael
> 
> > 
> > > > 
> > > > We need new fomula based on n_sectors for BP3 at least.
> > > 
> > > No they are the same, but yes there is a bug in the current
> > > implementation.
> > > 
> > > -michael
> > > 
> > > > 
> > > > > So for the 3 bit case the following flashes are border cases:
> > > > >   - 16mbit (less settings than slots)
> > > > >   - 32mbit (number of settings and free slots match)
> > > > >   - 64mbit (more settings than slots, first setting is
> > > > > discarded)
> > > > > 
> > > > > That being said, I suspect all the 16mbit flashes (and below)
> > > > > which
> > > > > have
> > > > > the _LOCK bit set are broken, because the entries has to be
> > > > > shifted.
> > > > > I'll
> > > > > look into that later. This is the same "issue" you have with
> > > > > the
> > > > > 4
> > > > > bits.
> > > > > So if this is fixed, you should not need another formula for
> > > > > the
> > > > > 4
> > > > > bit
> > > > > case.
> > > > > 
> > > > > > We need new calculation method for 4bit block protection
> > > > > > and
> > > > > > for
> > > > > > making
> > > > > > it more generic, I choose n_sectors.
> > > > > > 
> > > > > > On all the flashes I checked, n_sectors is proper value for
> > > > > > getting
> > > > > > block protected portion.
> > > > > > 
> > > > > > 		density	portion	n_sectors
> > > > > > W25M512JV	64MB	1/512	512
> > > > > > N25Q128A	16MB	1/256	256
> > > > > > N25Q512A	64MB	1/1024	1024
> > > > > > MT25QL02GCBB	256MB	1/4096	4096
> > > > > 
> > > > > The rules above apply to these flashes, too. Could you double
> > > > > check
> > > > > that?
> > > > > 
> > > > > -michael
> > > > > 
> > > > > > 
> > > > > > > > +		val = val << SR_BP_SHIFT;
> > > > > > > > +
> > > > > > > > +		if (val & BIT(5) && mask & SR_BP3_BIT6)
> > > > > > > > +			val = (val & ~BIT(5)) | BIT(6);
> > > > > > > > +	} else {
> > > > > > > > +		val = mask - (pow << SR_BP_SHIFT);
> > > > > > > > +	}
> > > > > > > > +
> > > > > > > >  	if (val & ~mask)
> > > > > > > >  		return -EINVAL;
> > > > > > > >  	/* Don't "lock" with no region! */
> > > > > > > > @@ -1983,6 +2057,13 @@ static int stm_unlock(struct
> > > > > > > > spi_nor
> > > > > > > > *nor,
> > > > > > > > loff_t ofs, uint64_t len)
> > > > > > > > 
> > > > > > > >  	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
> > > > > > > >  		tb_mask = SR_TB_BIT6;
> > > > > > > > +
> > > > > > > > +	if (nor->flags & SNOR_F_HAS_SR_BP3) {
> > > > > > > > +		if (nor->flags &
> > > > > > > > SNOR_F_HAS_SR_BP3_BIT6)
> > > > > > > > +			mask = mask | SR_BP3_BIT6;
> > > > > > > > +		else
> > > > > > > > +			mask = mask | SR_BP3_BIT5;
> > > > > > > > +	}
> > > > > > > >  	/*
> > > > > > > >  	 * Need largest pow such that:
> > > > > > > >  	 *
> > > > > > > > @@ -1995,13 +2076,20 @@ static int stm_unlock(struct
> > > > > > > > spi_nor
> > > > > > > > *nor,
> > > > > > > > loff_t ofs, uint64_t len)
> > > > > > > >  	pow = ilog2(mtd->size) -
> > > > > > > > order_base_2(lock_len);
> > > > > > > >  	if (lock_len == 0) {
> > > > > > > >  		val = 0; /* fully unlocked */
> > > > > > > > +	} else if (nor->flags & SNOR_F_HAS_SR_BP3) {
> > > > > > > > +		val = ilog2(nor->n_sectors) + 1 - pow;
> > > > > > > > +		val = val << SR_BP_SHIFT;
> > > > > > > > +
> > > > > > > > +		if (val & BIT(5) && mask & SR_BP3_BIT6)
> > > > > > > > +			val = (val & ~BIT(5)) | BIT(6);
> > > > > > > >  	} else {
> > > > > > > >  		val = mask - (pow << SR_BP_SHIFT);
> > > > > > > > -		/* Some power-of-two sizes are not
> > > > > > > > supported */
> > > > > > > > -		if (val & ~mask)
> > > > > > > > -			return -EINVAL;
> > > > > > > >  	}
> > > > > > > > 
> > > > > > > > +	/* Some power-of-two sizes are not supported */
> > > > > > > > +	if (val & ~mask)
> > > > > > > > +		return -EINVAL;
> > > > > > > > +
> > > > > > > >  	status_new = (status_old & ~mask & ~tb_mask) |
> > > > > > > > val;
> > > > > > > > 
> > > > > > > >  	/* Don't protect status register if we're fully
> > > > > > > > unlocked */
> > > > > > > > @@ -4736,6 +4824,7 @@ static void
> > > > > > > > spi_nor_info_init_params(struct
> > > > > > > > spi_nor *nor)
> > > > > > > >  	/* Set SPI NOR sizes. */
> > > > > > > >  	params->size = (u64)info->sector_size * info-
> > > > > > > > > n_sectors;
> > > > > > > > 
> > > > > > > >  	params->page_size = info->page_size;
> > > > > > > > +	params->n_sectors = info->n_sectors;
> > > > > > > > 
> > > > > > > >  	if (!(info->flags & SPI_NOR_NO_FR)) {
> > > > > > > >  		/* Default to Fast Read for DT and non-
> > > > > > > > DT
> > > > > > > > platform
> > > > > > > > devices. */
> > > > > > > > @@ -5192,6 +5281,11 @@ int spi_nor_scan(struct spi_nor
> > > > > > > > *nor,
> > > > > > > > const
> > > > > > > > char *name,
> > > > > > > >  		nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
> > > > > > > >  	if (info->flags & USE_CLSR)
> > > > > > > >  		nor->flags |= SNOR_F_USE_CLSR;
> > > > > > > > +	if (info->flags & SPI_NOR_HAS_BP3) {
> > > > > > > > +		nor->flags |= SNOR_F_HAS_SR_BP3;
> > > > > > > > +		if (info->flags & SPI_NOR_BP3_SR_BIT6)
> > > > > > > > +			nor->flags |=
> > > > > > > > SNOR_F_HAS_SR_BP3_BIT6;
> > > > > > > > +	}
> > > > > > > > 
> > > > > > > >  	if (info->flags & SPI_NOR_NO_ERASE)
> > > > > > > >  		mtd->flags |= MTD_NO_ERASE;
> > > > > > > > @@ -5199,6 +5293,7 @@ int spi_nor_scan(struct spi_nor
> > > > > > > > *nor,
> > > > > > > > const
> > > > > > > > char *name,
> > > > > > > >  	mtd->dev.parent = dev;
> > > > > > > >  	nor->page_size = params->page_size;
> > > > > > > >  	mtd->writebufsize = nor->page_size;
> > > > > > > > +	nor->n_sectors = params->n_sectors;
> > > > > > > > 
> > > > > > > >  	if (of_property_read_bool(np, "broken-flash-
> > > > > > > > reset"))
> > > > > > > >  		nor->flags |= SNOR_F_BROKEN_RESET;
> > > > > > > > diff --git a/include/linux/mtd/spi-nor.h
> > > > > > > > b/include/linux/mtd/spi-
> > > > > > > > nor.h
> > > > > > > > index 541c06d042e8..92d550501daf 100644
> > > > > > > > --- a/include/linux/mtd/spi-nor.h
> > > > > > > > +++ b/include/linux/mtd/spi-nor.h
> > > > > > > > @@ -129,7 +129,9 @@
> > > > > > > >  #define SR_BP1			BIT(3)	/* Block
> > > > > > > > protect 1
> > > > > > > > */
> > > > > > > >  #define SR_BP2			BIT(4)	/* Block
> > > > > > > > protect 2
> > > > > > > > */
> > > > > > > >  #define SR_TB_BIT5		BIT(5)	/* Top/Bottom
> > > > > > > > protect
> > > > > > > > */
> > > > > > > > +#define SR_BP3_BIT5		BIT(5)	/* Block
> > > > > > > > protect 3
> > > > > > > > */
> > > > > > > 
> > > > > > > maybe just name it SR_BP3? would also be more consistent
> > > > > > > with
> > > > > > > the
> > > > > > > proposal
> > > > > > > above.
> > > > > > > 
> > > > > > > >  #define SR_TB_BIT6		BIT(6)	/* Top/Bottom
> > > > > > > > protect
> > > > > > > > */
> > > > > > > > +#define SR_BP3_BIT6		BIT(6)	/* Block
> > > > > > > > protect 3
> > > > > > > > */
> > > > > > > >  #define SR_SRWD			BIT(7)	/* SR
> > > > > > > > write
> > > > > > > > protect
> > > > > > > > */
> > > > > > > >  /* Spansion/Cypress specific status bits */
> > > > > > > >  #define SR_E_ERR		BIT(5)
> > > > > > > > @@ -248,6 +250,8 @@ enum spi_nor_option_flags {
> > > > > > > >  	SNOR_F_HAS_16BIT_SR	= BIT(9),
> > > > > > > >  	SNOR_F_NO_READ_CR	= BIT(10),
> > > > > > > >  	SNOR_F_HAS_SR_TB_BIT6	= BIT(11),
> > > > > > > > +	SNOR_F_HAS_SR_BP3	= BIT(12),
> > > > > > > > +	SNOR_F_HAS_SR_BP3_BIT6	= BIT(13),
> > > > > > > > 
> > > > > > > >  };
> > > > > > > > 
> > > > > > > > @@ -519,6 +523,7 @@ struct spi_nor_locking_ops {
> > > > > > > >   *
> > > > > > > >   * @size:		the flash memory density in
> > > > > > > > bytes.
> > > > > > > >   * @page_size:		the page size of the SPI NOR
> > > > > > > > flash
> > > > > > > > memory.
> > > > > > > > + * @n_sectors:		number of sectors
> > > > > > > >   * @hwcaps:		describes the read and page
> > > > > > > > program
> > > > > > > > hardware
> > > > > > > >   *			capabilities.
> > > > > > > >   * @reads:		read capabilities ordered by
> > > > > > > > priority:
> > > > > > > > the
> > > > > > > > higher index
> > > > > > > > @@ -541,6 +546,7 @@ struct spi_nor_locking_ops {
> > > > > > > >  struct spi_nor_flash_parameter {
> > > > > > > >  	u64				size;
> > > > > > > >  	u32				page_size;
> > > > > > > > +	u16				n_sectors;
> > > > > > > > 
> > > > > > > >  	struct spi_nor_hwcaps		hwcaps;
> > > > > > > >  	struct spi_nor_read_command	reads[SNOR_CMD_
> > > > > > > > READ_MAX
> > > > > > > > ];
> > > > > > > > @@ -573,6 +579,7 @@ struct flash_info;
> > > > > > > >   * @bouncebuf_size:	size of the bounce buffer
> > > > > > > >   * @info:		spi-nor part JDEC MFR id and
> > > > > > > > other info
> > > > > > > >   * @page_size:		the page size of the SPI NOR
> > > > > > > > + * @n_sector:		number of sectors
> > > > > > > >   * @addr_width:		number of address bytes
> > > > > > > >   * @erase_opcode:	the opcode for erasing a sector
> > > > > > > >   * @read_opcode:	the read opcode
> > > > > > > > @@ -599,6 +606,7 @@ struct spi_nor {
> > > > > > > >  	size_t			bouncebuf_size;
> > > > > > > >  	const struct flash_info	*info;
> > > > > > > >  	u32			page_size;
> > > > > > > > +	u16			n_sectors;
> > > > > > > >  	u8			addr_width;
> > > > > > > >  	u8			erase_opcode;
> > > > > > > >  	u8			read_opcode;
> > > > > > > > --
> > > > > > > > 2.17.1
> > > > > > > > 
> > > > > > > > 
> > > > > > > > ______________________________________________________
> > > > > > > > Linux MTD discussion mailing list
> > > > > > > > 
> > > > > > 
> > > > > > 
> > > > 
> > > > 
> > 
> > 
https://protect2.fireeye.com/url?k=06b6dd5d-5b7d5a63-06b75612-0cc47a31309a-83164929001f7741&u=http://lists.infradead.org/mailman/listinfo/linux-mtd/
> > > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > 
> > > > > 
> > > 
> > > 
> 
> 

Thanks,
Jungseung Lee


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