To avoid name clashes unify all the function and static object names and
use one of the following prefixes which should be sufficiently unique:
- <vendor>_nor_
- <flash_family>_nor_
- <flash_part>_
There are no functional changes.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Pratyush Yadav <p.yadav@ti.com>
Link: https://lore.kernel.org/r/20220223134358.1914798-5-michael@walle.cc
Clarify for what the flash_info flags are used for. Split them in
four categories and a bool:
1/ FLAGS: flags that indicate support that is not defined by the JESD216
standard in its SFDP tables.
2/ NO_SFDP_FLAGS: these flags are used when the flash does not define the
SFDP tables. These flags indicate support that can be discovered via
SFDP. Used together with SPI_NOR_SKIP_SFDP flag.
3/ FIXUP_FLAGS: flags that indicate support that can be discovered
via SFDP ideally, but can not be discovered for this particular flash
because the SFDP table that indicates this support is not defined by
the flash. In case the table for this support is defined but has wrong
values, one should instead use a post_sfdp() hook to set the SNOR_F
equivalent flag.
4/ MFR_FLAGS: manufacturer private flags. Used in the manufacturer
fixup hooks to differentiate support between flashes of the same
manufacturer.
5/ PARSE_SFDP: sets info->parse_sfdp to true. All flash_info entries
that support SFDP should be converted to set info->parse_sfdp to true.
SPI NOR flashes that statically declare one of the
SPI_NOR_{DUAL, QUAD, OCTAL, OCTAL_DTR}_READ flags and do not support
the RDSFDP command are gratuiously receiving the RDSFDP command
in the attempt of parsing the SFDP tables. It is not desirable to issue
commands that are not supported, so introduce PARSE_SFDP to help on this
situation.
New flash additions/updates should be declared/updated to use either
PARSE_SFDP or SPI_NOR_SKIP_SFDP. Once all the flash_info entries are
converted to use SPI_NOR_SKIP_SFDP or PARSE_SFDP, we can get rid of the
SPI_NOR_SKIP_SFDP flag and use just the bool nor->info->parse_sfdp to
determine whether to parse SFDP or not. SPI_NOR_SKIP_SFDP flag is kept
just as a way to differentiate whether a flash is converted to the new
flags logic or not.
Support that can be discovered when parsing SFDP should not be duplicated
by explicit flags at flash declaration. All the flash parameters will be
discovered when parsing SFDP. Sometimes manufacturers wrongly define some
fields in the SFDP tables. If that's the case, SFDP data can be amended
with the fixups() hooks. It is not common, but if the SFDP tables are
entirely wrong, and it does not worth the hassle to tweak the SFDP
parameters by using the fixups hooks, or if the flash does not define the
SFDP tables at all, then statically init the flash with the
SPI_NOR_SKIP_SFDP flag and specify the rest of flash capabilities with
the flash info flags.
With time, we want to convert all flashes to use PARSE_SFDP and
stop triggering the SFDP parsing with the
SPI_NOR_{DUAL, QUAD, OCTAL*}_READ flags. Getting rid of the
SPI_NOR_{OCTAL, OCTAL_DTR}_READ trigger is easily achievable,
the rest are a long term goal.
Manufacturer specific flags like USE_CLSR, USE_FSR, SPI_NOR_XSR_RDY,
will be removed in a future series.
No functional changes intended in this patch.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Pratyush Yadav <p.yadav@ti.com>
Link: https://lore.kernel.org/r/20211207140254.87681-7-tudor.ambarus@microchip.com
Traditionally, Linux unlocks the whole flash because there are legacy
devices which has the write protection bits set by default at startup.
If you actually want to use the flash protection bits, eg. because there
is a read-only part for a bootloader, this automatic unlocking is
harmful. If there is no hardware write protection in place (usually
called WP#), a startup of the kernel just discards this protection.
I've gone through the datasheets of all the flashes (except the Intel
ones where I could not find any datasheet nor reference) which supports
the unlocking feature and looked how the sector protection was
implemented. The currently supported flashes can be divided into the
following two categories:
(1) block protection bits are non-volatile. Thus they keep their values
at reset and power-cycle
(2) flashes where these bits are volatile. After reset or power-cycle,
the whole memory array is protected.
(a) some devices needs a special "Global Unprotect" command, eg.
the Atmel AT25DF041A.
(b) some devices require to clear the BPn bits in the status
register.
Due to the reasons above, we do not want to clear the bits for flashes
which belong to category (1). Fortunately for us, only Atmel flashes
fall into category (2a). Implement the "Global Protect" and "Global
Unprotect" commands for these. For (2b) we can use normal block
protection locking scheme.
This patch adds a new flag to indicate the case (2). Only if we have
such a flash we unlock the whole flash array. To be backwards compatible
it also introduces a kernel configuration option which restores the
complete legacy behavior ("Disable write protection on any flashes").
Hopefully, this will clean up "unlock the entire flash for legacy
devices" once and for all.
For reference here are the actually commits which introduced the legacy
behavior (and extended the behavior to other chip manufacturers):
commit f80e521c91 ("mtd: m25p80: add support for the Intel/Numonyx {16,32,64}0S33B SPI flash chips")
commit ea60658a08 ("mtd: m25p80: disable SST software protection bits by default")
commit 7228982442 ("[MTD] m25p80: fix bug - ATmel spi flash fails to be copied to")
Actually, this might also fix handling of the Atmel AT25DF flashes,
because the original commit 7228982442 ("[MTD] m25p80: fix bug -
ATmel spi flash fails to be copied to") was writing a 0 to the status
register, which is a "Global Unprotect". This might not be the case in
the current code which only handles the block protection bits BP2, BP1
and BP0. Thus, it depends on the current contents of the status register
if this unlock actually corresponds to a "Global Unprotect" command. In
the worst case, the current code might leave the AT25DF flashes in a
write protected state.
The commit 191f5c2ed4 ("mtd: spi-nor: use 16-bit WRR command when QE
is set on spansion flashes") changed that behavior by just clearing BP2
to BP0 instead of writing a 0 to the status register.
Further, the commit 3e0930f109 ("mtd: spi-nor: Rework the disabling
of block write protection") expanded the unlock_all() feature to ANY
flash which supports locking.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201203162959.29589-8-michael@walle.cc
Create a SPI NOR manufacturer driver for ESMT chips, and move the
ESMT definitions outside of core.c.
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
