| Message ID | 1556474956-27786-4-git-send-email-sagar.kadam@sifive.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | add support for is25wp256 spi-nor device. | expand |
On Sun, 28 Apr 2019, Sagar Shrikant Kadam wrote: > The locking scheme for ISSI devices is based on stm_lock mechanism. > The is25xxxxx devices have 4 bits for selecting the range of blocks to > be locked for write. > > The current implementation, blocks entire 512 blocks of flash memory. > > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com> > --- > drivers/mtd/spi-nor/spi-nor.c | 60 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 60 insertions(+) > > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c > index 81c7b3e..2dba7e9 100644 > --- a/drivers/mtd/spi-nor/spi-nor.c > +++ b/drivers/mtd/spi-nor/spi-nor.c > @@ -1459,6 +1459,65 @@ static int macronix_quad_enable(struct spi_nor *nor) > > return 0; > } > +/** The above sequence indicates a kerneldoc-style comment, but the format of the comment is not in kerneldoc format. Please fix this comment to conform with https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/kernel-docs.rst > + * Lock a region of the flash.Implementation is based on stm_lock > + * Supports the block protection bits BP{0,1,2,3} in the status register > + * Returns negative on errors, 0 on success. > + */ > +static int issi_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) > +{ Almost all of this function is copied and pasted from stm_lock(). Please don't do this: it adds bloat, makes the code hard to maintain, and increases the risk that fixes will only target one function rather than both. Instead please pull the common code out into a separate static function. > + struct mtd_info *mtd = &nor->mtd; > + int status_old, status_new; > + u8 mask = SR_BP3 | SR_BP2 | SR_BP1 | SR_BP0; > + u8 shift = ffs(mask) - 1, pow, val = 0; > + loff_t lock_len; > + bool use_top = true; > + > + status_old = read_sr(nor); > + > + if (status_old < 0) > + return status_old; > + > + /* lock_len: length of region that should end up locked */ > + if (use_top) > + lock_len = mtd->size - ofs; > + else > + lock_len = ofs + len; > + > + /* > + * Need smallest pow such that: > + * > + * 1 / (2^pow) <= (len / size) > + * > + * so (assuming power-of-2 size) we do: > + * > + * pow = ceil(log2(size / len)) = log2(size) - floor(log2(len)) > + */ > + pow = ilog2(mtd->size) - ilog2(lock_len); > + val = mask - (pow << shift); > + > + if (val & ~mask) > + return -EINVAL; > + > + /* Don't "lock" with no region! */ > + if (!(val & mask)) > + return -EINVAL; > + > + status_new = (status_old & ~mask & ~SR_TB) | val; > + > + /* Disallow further writes if WP pin is asserted */ > + status_new |= SR_SRWD; > + > + /* Don't bother if they're the same */ > + if (status_new == status_old) > + return 0; > + > + /* Only modify protection if it will not unlock other areas */ > + if ((status_new & mask) < (status_old & mask)) > + return -EINVAL; > + > + return write_sr_and_check(nor, status_new, mask); > +} > > /** > * issi_unlock() - clear BP[0123] write-protection. > @@ -4121,6 +4180,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, > /* NOR protection support for ISSI chips */ > if (JEDEC_MFR(info) == SNOR_MFR_ISSI || > info->flags & SPI_NOR_HAS_LOCK) { > + nor->flash_lock = issi_lock; > nor->flash_unlock = issi_unlock; > > } > -- > 1.9.1 > >
On Tue, 30 Apr 2019, Paul Walmsley wrote: > The above sequence indicates a kerneldoc-style comment, but the format of > the comment is not in kerneldoc format. Please fix this comment to > conform with > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/kernel-docs.rst This, rather: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/doc-guide/kernel-doc.rst#n57 - Paul
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c index 81c7b3e..2dba7e9 100644 --- a/drivers/mtd/spi-nor/spi-nor.c +++ b/drivers/mtd/spi-nor/spi-nor.c @@ -1459,6 +1459,65 @@ static int macronix_quad_enable(struct spi_nor *nor) return 0; } +/** + * Lock a region of the flash.Implementation is based on stm_lock + * Supports the block protection bits BP{0,1,2,3} in the status register + * Returns negative on errors, 0 on success. + */ +static int issi_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) +{ + struct mtd_info *mtd = &nor->mtd; + int status_old, status_new; + u8 mask = SR_BP3 | SR_BP2 | SR_BP1 | SR_BP0; + u8 shift = ffs(mask) - 1, pow, val = 0; + loff_t lock_len; + bool use_top = true; + + status_old = read_sr(nor); + + if (status_old < 0) + return status_old; + + /* lock_len: length of region that should end up locked */ + if (use_top) + lock_len = mtd->size - ofs; + else + lock_len = ofs + len; + + /* + * Need smallest pow such that: + * + * 1 / (2^pow) <= (len / size) + * + * so (assuming power-of-2 size) we do: + * + * pow = ceil(log2(size / len)) = log2(size) - floor(log2(len)) + */ + pow = ilog2(mtd->size) - ilog2(lock_len); + val = mask - (pow << shift); + + if (val & ~mask) + return -EINVAL; + + /* Don't "lock" with no region! */ + if (!(val & mask)) + return -EINVAL; + + status_new = (status_old & ~mask & ~SR_TB) | val; + + /* Disallow further writes if WP pin is asserted */ + status_new |= SR_SRWD; + + /* Don't bother if they're the same */ + if (status_new == status_old) + return 0; + + /* Only modify protection if it will not unlock other areas */ + if ((status_new & mask) < (status_old & mask)) + return -EINVAL; + + return write_sr_and_check(nor, status_new, mask); +} /** * issi_unlock() - clear BP[0123] write-protection. @@ -4121,6 +4180,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, /* NOR protection support for ISSI chips */ if (JEDEC_MFR(info) == SNOR_MFR_ISSI || info->flags & SPI_NOR_HAS_LOCK) { + nor->flash_lock = issi_lock; nor->flash_unlock = issi_unlock; }
The locking scheme for ISSI devices is based on stm_lock mechanism. The is25xxxxx devices have 4 bits for selecting the range of blocks to be locked for write. The current implementation, blocks entire 512 blocks of flash memory. Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com> --- drivers/mtd/spi-nor/spi-nor.c | 60 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+)