3 Commits

Author	SHA1	Message	Date
Tudor Ambarus	ec1c0e9960	mtd: spi-nor: Rework the flash_info flags ... 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	2021-12-07 17:05:11 +02:00
Michael Walle	31ad3eff09	mtd: spi-nor: keep lock bits if they are non-volatile ... 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 f80e521c916cb ("mtd: m25p80: add support for the Intel/Numonyx {16,32,64}0S33B SPI flash chips") commit ea60658a08f8f ("mtd: m25p80: disable SST software protection bits by default") commit 7228982442365 ("[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 7228982442365 ("[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 191f5c2ed4b6f ("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 3e0930f109e76 ("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	2020-12-07 23:01:15 +05:30
Boris Brezillon	74c7e0e3b9	mtd: spi-nor: Move ESMT bits out of core.c ... 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>	2020-03-17 09:28:02 +02:00