commit 5c1ebe7f73f9166893c3459915db8a09d6d1d715 upstream.

If the device can't support block writes then don't attempt to use raw
syncing which will automatically generate block writes for adjacent
registers, use the existing _single() block syncing implementation.

Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Try to speed up I/O a little by not synchronising until we are finished
scheduling writes. A brief survey of existing users suggests we have none
that would currently benefit from an async cache sync.

Signed-off-by: Mark Brown <broonie@linaro.org>

Rather than passing a flag around through the entire call stack store it
in the regmap struct and read it when required. This minimises the
visibility of the feature through the API, minimising the code updates
needed to use it more widely.

Signed-off-by: Mark Brown <broonie@linaro.org>

With devices which have a dense and small register map but placed at a large
offset the global cache_present bitmap imposes a huge memory overhead. Making
the cache_present per rbtree node avoids the issue and easily reduces the memory
footprint by a factor of ten. For devices with a more sparse map or without a
large base register offset the memory usage might increase slightly by a few
bytes, but not significantly. E.g. for a device which has ~50 registers at
offset 0x4000 the memory footprint of the register cache goes down form 2496
bytes to 175 bytes.

Moving the bitmap to a per node basis means that the handling of the bitmap is
now cache implementation specific and can no longer be managed by the core. The
regcache_sync_block() function is extended by a additional parameter so that the
cache implementation can tell the core which registers in the block are set and
which are not. The parameter is optional and if NULL the core assumes that all
registers are set. The rbtree cache also needs to implement its own drop
callback instead of relying on the core to handle this.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

The regmap_writeable() check should not be done in
regcache_write() because this prevents read-only
registers to be cached. After a read on a read-only
register its value will not be stored in the cache
and the next time someone will try to read it the
value will be read from the bus instead of the
cache.

Instead the regmap_writeable() check should be done
in _regmap_write() to prevent callers from writing
to read-only registers.

Signed-off-by: Ionut Nicu <ioan.nicu.ext@nsn.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

regcache_sync_block_raw_flush() expects the address of the register after last
register that needs to be synced as its parameter. But the last call to
regcache_sync_block_raw_flush() in regcache_sync_block_raw() passes the address
of the last register in the block. This effectively always skips over the last
register in a block, even if it needs to be synced. In order to fix it increase
the address by one register.

The issue was introduced in commit 75a5f89 ("regmap: cache: Write consecutive
registers in a single block write").

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

This can be used for cache types for which syncing values one by one is
equally efficient as syncing a range, such as the flat cache.

Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

The parameter passed to the regmap lock/unlock callbacks needs to be
map->lock_arg, regcache passes just map. This works fine in the case that no
custom locking callbacks are used, since in this case map->lock_arg equals map,
but will break when custom locking callbacks are used. The issue was introduced
in commit 0d4529c5 ("regmap: make lock/unlock functions customizable") and is
fixed by this patch.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Allow drivers to discard parts of the register cache, for example if part
of the hardware has been reset.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>