On many MIPS systems the endianness of IP blocks is kept the same as
that of the CPU by the hardware. This includes the system controllers
on these systems which are controlled via syscon which uses the regmap
API which used readl() and writel() to interact with the hardware,
meaning that all writes are converted to little endian when writing to
the hardware. This caused a bad interaction with the regmap core in big
endian mode since it was not aware of the byte swapping and so ended up
performing little endian writes.
Unfortunately when this issue was noticed it was addressed by updating
the DT for the affected devices to specify them as little endian. This
happened to work since it resulted in two endianness swaps which
cancelled each other out and gave little endian behaviour but meant that
the DT was clearly not accurately describing the hardware.
The intention of commit 29bb45f25f (regmap-mmio: Use native
endianness for read/write) was to fix this by making regmap default to
native endianness but this breaks most other MMIO users where the
hardware has a fixed endianness and the implementation uses the __raw
accessors which are not intended to be used outside of architecture
code. Instead use the newly added native-endian DT property to say
exactly what we want for these systems.
Fixes: 29bb45f25f (regmap-mmio: Use native endianness for read/write)
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS updates from Ralf Baechle:
"This is the main pull request for MIPS for 4.5 plus some 4.4 fixes.
The executive summary:
- ATH79 platform improvments, use DT bindings for the ATH79 USB PHY.
- Avoid useless rebuilds for zboot.
- jz4780: Add NEMC, BCH and NAND device tree nodes
- Initial support for the MicroChip's DT platform. As all the device
drivers are missing this is still of limited use.
- Some Loongson3 cleanups.
- The unavoidable whitespace polishing.
- Reduce clock skew when synchronizing the CPU cycle counters on CPU
startup.
- Add MIPS R6 fixes.
- Lots of cleanups across arch/mips as fallout from KVM.
- Lots of minor fixes and changes for IEEE 754-2008 support to the
FPU emulator / fp-assist software.
- Minor Ralink, BCM47xx and bcm963xx platform support improvments.
- Support SMP on BCM63168"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (84 commits)
MIPS: zboot: Add support for serial debug using the PROM
MIPS: zboot: Avoid useless rebuilds
MIPS: BMIPS: Enable ARCH_WANT_OPTIONAL_GPIOLIB
MIPS: bcm63xx: nvram: Remove unused bcm63xx_nvram_get_psi_size() function
MIPS: bcm963xx: Update bcm_tag field image_sequence
MIPS: bcm963xx: Move extended flash address to bcm_tag header file
MIPS: bcm963xx: Move Broadcom BCM963xx image tag data structure
MIPS: bcm63xx: nvram: Use nvram structure definition from header file
MIPS: bcm963xx: Add Broadcom BCM963xx board nvram data structure
MAINTAINERS: Add KVM for MIPS entry
MIPS: KVM: Add missing newline to kvm_err()
MIPS: Move KVM specific opcodes into asm/inst.h
MIPS: KVM: Use cacheops.h definitions
MIPS: Break down cacheops.h definitions
MIPS: Use EXCCODE_ constants with set_except_vector()
MIPS: Update trap codes
MIPS: Move Cause.ExcCode trap codes to mipsregs.h
MIPS: KVM: Make kvm_mips_{init,exit}() static
MIPS: KVM: Refactor added offsetof()s
MIPS: KVM: Convert EXPORT_SYMBOL to _GPL
...
The regmap API has an endianness setting for formatting reads and writes.
This can be set by the usual DT "little-endian" and "big-endian" properties.
To work properly the associated regmap_bus needs to read/write in native
endian.
The "syscon" DT device binding creates an mmio-based regmap_bus which
performs all reads/writes as little-endian. These values are then converted
again by regmap, which means that all of the MIPS BCM boards (which are
big-endian) have been declared as "little-endian" to get regmap to convert
them back to big-endian.
Modify regmap-mmio to use the native-endian functions __raw_read*() and
__raw_write*() instead of the little-endian functions read*() and
write*().
Modify the big-endian MIPS BCM boards to use what will now be the correct
endianness instead of pretending that the devices are little-endian.
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Mark Brown <broonie@kernel.org>
