Commit 59b356ffd0 ("mtd: m25p80: restore the status of SPI flash when
exiting") is the latest from a long history of attempts to add reboot
handling to handle stateful addressing modes on SPI flash. Some prior
mostly-related discussions:
http://lists.infradead.org/pipermail/linux-mtd/2013-March/046343.html
[PATCH 1/3] mtd: m25p80: utilize dedicated 4-byte addressing commands
http://lists.infradead.org/pipermail/barebox/2014-September/020682.html
[RFC] MTD m25p80 3-byte addressing and boot problem
http://lists.infradead.org/pipermail/linux-mtd/2015-February/057683.html
[PATCH 2/2] m25p80: if supported put chip to deep power down if not used
Previously, attempts to add reboot-time software reset handling were
rejected, but the latest attempt was not.
Quick summary of the problem:
Some systems (e.g., boot ROM or bootloader) assume that they can read
initial boot code from their SPI flash using 3-byte addressing. If the
flash is left in 4-byte mode after reset, these systems won't boot. The
above patch provided a shutdown/remove hook to attempt to reset the
addressing mode before we reboot. Notably, this patch misses out on
huge classes of unexpected reboots (e.g., crashes, watchdog resets).
Unfortunately, it is essentially impossible to solve this problem 100%:
if your system doesn't know how to reset the SPI flash to power-on
defaults at initialization time, no amount of software can really rescue
you -- there will always be a chance of some unexpected reset that
leaves your flash in an addressing mode that your boot sequence didn't
expect.
While it is not directly harmful to perform hacks like the
aforementioned commit on all 4-byte addressing flash, a
properly-designed system should not need the hack -- and in fact,
providing this hack may mask the fact that a given system is indeed
broken. So this patch attempts to apply this unsound hack more narrowly,
providing a strong suggestion to developers and system designers that
this is truly a hack. With luck, system designers can catch their errors
early on in their development cycle, rather than applying this hack long
term. But apparently enough systems are out in the wild that we still
have to provide this hack.
Document a new device tree property to denote systems that do not have a
proper hardware (or software) reset mechanism, and apply the hack (with
a loud warning) only in this case.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
This reverts commit b07815d4ea.
The reverted commit was merged into v4-15-rc1 by mistake: it was taken
from the IMX tree but the patch has never been sent to linux-mtd nor
reviewed by any spi-nor maintainers.
Actually, it would have been rejected since we add new values for the
'compatible' DT property only for SPI NOR memories that don't support
the JEDEC READ ID op code (0x9F).
Both en25s64 and sst25wf040b support the JEDEC READ ID op code, hence
should use the "jedec,spi-nor" string alone as 'compatible' value.
See the following link for more details:
http://lists.infradead.org/pipermail/linux-mtd/2017-November/077425.html
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
General changes:
* Unconfuse get_unmapped_area and point/unpoint driver methods
* New partition parser: sharpslpart
* Kill GENERIC_IO
* Various fixes
NAND changes:
* Add a flag to mark NANDs that require 3 address cycles to encode a
page address
* Set a default ECC/free layout when NAND_ECC_NONE is requested
* Fix a bug in panic_nand_write()
* Another batch of cleanups for the denali driver
* Fix PM support in the atmel driver
* Remove support for platform data in the omap driver
* Fix subpage write in the omap driver
* Fix irq handling in the mtk driver
* Change link order of mtk_ecc and mtk_nand drivers to speed up boot
time
* Change log level of ECC error messages in the mxc driver
* Patch the pxa3xx driver to support Armada 8k platforms
* Add BAM DMA support to the qcom driver
* Convert gpio-nand to the GPIO desc API
* Fix ECC handling in the mt29f driver
SPI-NOR changes:
* Introduce system power management support
* New mechanism to select the proper .quad_enable() hook by JEDEC ID,
when needed, instead of only by manufacturer ID
* Add support to new memory parts from Gigadevice, Winbond, Macronix and
Everspin
* Maintainance for Cadence, Intel, Mediatek and STM32 drivers
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Merge tag 'for-linus-20171120' of git://git.infradead.org/linux-mtd
Pull MTD updates from Richard Weinberger:
"General changes:
- Unconfuse get_unmapped_area and point/unpoint driver methods
- New partition parser: sharpslpart
- Kill GENERIC_IO
- Various fixes
NAND changes:
- Add a flag to mark NANDs that require 3 address cycles to encode a
page address
- Set a default ECC/free layout when NAND_ECC_NONE is requested
- Fix a bug in panic_nand_write()
- Another batch of cleanups for the denali driver
- Fix PM support in the atmel driver
- Remove support for platform data in the omap driver
- Fix subpage write in the omap driver
- Fix irq handling in the mtk driver
- Change link order of mtk_ecc and mtk_nand drivers to speed up boot
time
- Change log level of ECC error messages in the mxc driver
- Patch the pxa3xx driver to support Armada 8k platforms
- Add BAM DMA support to the qcom driver
- Convert gpio-nand to the GPIO desc API
- Fix ECC handling in the mt29f driver
SPI-NOR changes:
- Introduce system power management support
- New mechanism to select the proper .quad_enable() hook by JEDEC
ID, when needed, instead of only by manufacturer ID
- Add support to new memory parts from Gigadevice, Winbond, Macronix
and Everspin
- Maintainance for Cadence, Intel, Mediatek and STM32 drivers"
* tag 'for-linus-20171120' of git://git.infradead.org/linux-mtd: (85 commits)
mtd: Avoid probe failures when mtd->dbg.dfs_dir is invalid
mtd: sharpslpart: Add sharpslpart partition parser
mtd: Add sanity checks in mtd_write/read_oob()
mtd: remove the get_unmapped_area method
mtd: implement mtd_get_unmapped_area() using the point method
mtd: chips/map_rom.c: implement point and unpoint methods
mtd: chips/map_ram.c: implement point and unpoint methods
mtd: mtdram: properly handle the phys argument in the point method
mtd: mtdswap: fix spelling mistake: 'TRESHOLD' -> 'THRESHOLD'
mtd: slram: use memremap() instead of ioremap()
kconfig: kill off GENERIC_IO option
mtd: Fix C++ comment in include/linux/mtd/mtd.h
mtd: constify mtd_partition
mtd: plat-ram: Replace manual resource management by devm
mtd: nand: Fix writing mtdoops to nand flash.
mtd: intel-spi: Add Intel Lewisburg PCH SPI super SKU PCI ID
mtd: nand: mtk: fix infinite ECC decode IRQ issue
mtd: spi-nor: Add support for mr25h128
mtd: nand: mtk: change the compile sequence of mtk_nand.o and mtk_ecc.o
mtd: spi-nor: enable 4B opcodes for mx66l51235l
...
Add Everspin mr25h128 16KB MRAM to the list of supported chips.
Signed-off-by: Philipp Puschmann <pp@emlix.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
The chip sst25wf040b and en25s64 are compatible with SPI NOR flash.
Signed-off-by: Yuan Yao <yao.yuan@nxp.com>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
W25Q64 is found on TI's AM335x ICEv2 board. Add it to list
for supported SPI flash devices. This flash can be identified
using JEDEC READ ID opcode.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
The MR25 family doesn't support JEDEC, so they need explicit mentioning
in the list of supported spi IDs. This makes it possible to add these
using for example:
compatible = "everspin,mr25h40";
There was already an entry for mr25h256. Move that one out of the "keep
for compatibility" section and put in a new group for Everspin MRAMs.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Pull the supported chip names from drivers/mtd/devices/m25p80.c and stop
pointing readers to Linux code.
Also (although I see this habit repeated throughout the
Documentation/devicetree/bindings/ tree), stop using the title "driver"
in this file, when we're trying explicitly to describe hardware, not
software.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: <devicetree@vger.kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
In commit 8ff16cf77c ("Documentation: devicetree: m25p80: add "nor-jedec"
binding"), we added a generic "nor-jedec" binding to catch all
mostly-compatible SPI NOR flash which can be detected via the READ ID
opcode (0x9F). This was discussed and reviewed at the time, however
objections have come up since then as part of this discussion:
http://lkml.kernel.org/g/20150511224646.GJ32500@ld-irv-0074
It seems the parties involved agree that "jedec,spi-nor" does a better
job of capturing the fact that this is SPI-specific, not just any NOR
flash.
This binding was only merged for v4.1-rc1, so it's still OK to change
the naming.
At the same time, let's move the documentation to a better name.
Next up: stop referring to code (drivers/mtd/devices/m25p80.c) from the
documentation.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Rafał Miłecki <zajec5@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: devicetree@vger.kernel.org
Acked-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Brian Norris