regmap: Drop initial version of maximum transfer length fixes

When problems were noticed with the register address not being taken
into account when limiting raw transfers with I2C devices we fixed this
in the core. Unfortunately it has subsequently been realised that a lot
of buses were relying on the prior behaviour, partly due to unclear
documentation not making it obvious what was intended in the core. This
is all more involved to fix than is sensible for a fix commit so let's
just drop the original fixes, a separate commit will fix the originally
observed problem in an I2C specific way

Fixes: 3981514180c9 ("regmap: Account for register length when chunking")
Fixes: c8e796895e23 ("regmap: spi-avmm: Fix regmap_bus max_raw_write")
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230712-regmap-max-transfer-v1-1-80e2aed22e83@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

regmap: spi-avmm: Fix regmap_bus max_raw_write

The max_raw_write member of the regmap_spi_avmm_bus structure is defined
as:
.max_raw_write = SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT

SPI_AVMM_VAL_SIZE == 4 and MAX_WRITE_CNT == 1 so this results in a
maximum write transfer size of 4 bytes which provides only enough space to
transfer the address of the target register. It provides no space for the
value to be transferred. This bug became an issue (divide-by-zero in
_regmap_raw_write()) after the following was accepted into mainline:

commit 3981514180c9 ("regmap: Account for register length when chunking")

Change max_raw_write to include space (4 additional bytes) for both the
register address and value:

.max_raw_write = SPI_AVMM_REG_SIZE + SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT

Fixes: 7f9fb67358a2 ("regmap: add Intel SPI Slave to AVMM Bus Bridge support")
Reviewed-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Link: https://lore.kernel.org/r/20230620202824.380313-1-russell.h.weight@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regmap: spi-avmm: Use swabXX_array() helpers

Since we have a few helpers to swab elements of a given size in an array
use them instead of open coded variants.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220831212744.56435-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

regmap: add Intel SPI Slave to AVMM Bus Bridge support

This patch add support for regmap APIs that are intended to be used by
the drivers of some SPI slave chips which integrate the "SPI slave to
Avalon Master Bridge" (spi-avmm) IP.

The spi-avmm IP acts as a bridge to convert encoded streams of bytes
from the host to the chip's internal register read/write on Avalon bus.
The driver implements the register read/write operations for a generic
SPI master to access the sub devices behind spi-avmm bridge.

Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Reviewed-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Link: https://lore.kernel.org/r/1597822497-25107-2-git-send-email-yilun.xu@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>