This patch adds support for LZO compression when storing the register
cache.

For a typical device whose register map would normally occupy 25kB or 50kB
by using the LZO compression technique, one can get down to ~5-7kB.  There
might be a performance penalty associated with each individual read/write
due to decompressing/compressing the underlying cache, however that should not
be noticeable.  These memory benefits depend on whether the target architecture
can get rid of the memory occupied by the original register defaults cache
which is marked as __devinitconst.  Nevertheless there will be some memory
gain even if the target architecture can't get rid of the original register
map, this should be around ~30-32kB instead of 50kB.
Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

This patch adds support for the rbtree cache compression type.

Each rbnode manages a variable length block of registers.  There can be no
two nodes with overlapping blocks.  Each block has a base register and a
currently top register, all the other registers, if any, lie in between these
two and in ascending order.

The reasoning behind the construction of this rbtree is simple.  In the
snd_soc_rbtree_cache_init() function, we iterate over the register defaults
provided by the regcache core.  For each register value that is non-zero we
insert it in the rbtree.  In order to determine in which rbnode we need
to add the register, we first look if there is another register already
added that is adjacent to the one we are about to add.  If that is the case
we append it in that rbnode block, otherwise we create a new rbnode
with a single register in its block and add it to the tree.

There are various optimizations across the implementation to speed up lookups
by caching the most recently used rbnode.
Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

This is the simplest form of a cache available in regcache.  Any
registers whose default value is 0 are ignored.  If any of those
registers are modified in the future, they will be placed in the
cache on demand.  The cache layout is essentially using the provided
register defaults by the regcache core directly and does not re-map
it to another representation.
Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

This patch introduces caching support for regmap.  The regcache API
has evolved essentially out of ASoC soc-cache so most of the actual
caching types (except LZO) have been tested in the past.

The purpose of regcache is to optimize in time and space the handling
of register caches.  Time optimization is achieved by not having to go
over a slow bus like I2C to read the value of a register, instead it is
cached locally in memory and can be retrieved faster.  Regarding space
optimization, some of the cache types are better at packing the caches,
for e.g. the rbtree and the LZO caches.  By doing this the sacrifice in
time still wins over doing I2C transactions.
Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Add the externally visible interface introduced by Lars-Peter's commit
6f3064 (regmap: Add support for device specific write and read flag
masks) separately in order to allow merge into other subsystems for
integration with drivers.  Drivers relying on this feature will not be
functional until they are merged with the implementation.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Make the debugfs stubs static inline to avoid future compilation issues due to
duplicated symbols when CONFIG_DEBUG_FS=n once internal.h is included by
multiple source files.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Some buses like SPI have no standard notation of read or write operations.
The general scheme here is to set or clear specific bits in the register
address to indicate whether the operation is a read or write. We already
support having a read flag mask per bus, but as there is no standard
the bits which need to be set or cleared differ between devices and vendors,
thus we need a mechanism to specify them per device.

This patch adds two new entries to the regmap_config struct, read_flag_mask and
write_flag_mask. These will be or'ed onto the top byte when doing a read or
write operation. If both masks are empty the device will fallback to the
regmap_bus masks.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Off by one in the array iteration.
Reported-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

No longer used as users link directly with the bus types so the core
module infrastructure does refcounting for us.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

The conversion to per bus type registration functions means we don't need
to do module_get()s to hold the bus types in memory (their users will link
to them) so we removed all those calls. This left module_put() calls in
the cleanup paths which aren't needed and which cause unbalanced puts if
we ever try to unload anything.
Reported-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

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

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>

Lets us see the register map in debugfs and will enable us to push
access checking down into the regmap API.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>

Factor out the register read/write code to use the register map API.  We
still need some wm831x specific code and locking in place to check that
the user key is handled correctly but only on the write side, reads are
not affected by the key.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>

It is useful for the register cache code to be able to specify the
default values for the device registers. The major use is when restoring
the register cache after suspend, knowing the register defaults allows
us to skip registers that are at their default values when we resume which
can be a substantial win on larger modern devices. For some devices
(mostly older ones) the hardware does not support readback so the only way we
can know the values is from code and so initializing the cache with default
values makes it much easier for drivers work with read/modify/write
updates.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Let userspace know what the access map for the device is. This is helpful
for verifying that the access map is correctly configured and could also
be useful for programs that try to work with the data. File format is:

register: R W V P

where R, W, V and P are 'y' or 'n' showing readable, writable, volatile
and precious respectively.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

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

We're going to be using these in quite a few places so factor out the
readable/writable/volatile/precious checks.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

CONFIG_REGMAP_I2C/SPI are set to m when selected by a tristate config
option that's set to m. The regmap modules don't specify a license, so
fail to link to regmap_init at load time, since that is EXPORT_SYMBOL_GPL.
Fix this by specifying a license for the regmap modules.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

We no longer enumerate the bus types, we rely on the driver telling us
this on init.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

x86_64 size_t is not an int but the printf format specifier for size_t
should be an int.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>

x86_64 warns as size_t is not an int.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>

Field names didn't match between the documentation and the code.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

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

Copy over the read parts of the ASoC debugfs implementation into regmap,
allowing users to see what the register values the device has are at
runtime. The implementation, especially the support for seeking, is
mostly due to Dimitris Papastamos' work in ASoC.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Allowing the implementation to be multi-file.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

This is mainly intended to be used by devices which can dynamically
block register writes at runtime, for other devices there is usually
limited value.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Trace single register reads and writes, plus start/stop tracepoints for
the actual I/O to see where we're spending time. This makes it easy to
have always on logging without overwhelming the logs and also lets us take
advantage of all the context and time information that the trace subsystem
collects for us.

We don't currently trace register values for bulk operations as this would
add complexity and overhead parsing the cooked data that's being worked
with.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

When doing a single register write we use work_buf for both the register
and the value with the buffer formatted for sending directly to the device
so we can just do a write() directly. This saves allocating a temporary
buffer if we can't do gather writes and is likely to be faster than doing
a gather write.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Some devices are sensitive to reads on their registers, especially for
things like clear on read interrupt status registers. Avoid creating
problems with these with things like debugfs by allowing drivers to tell
the core about them. If a register is marked as precious then the core
will not internally generate any reads of it.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

This is currently unused but we need to know which registers exist and
their properties in order to implement diagnostics like register map
dumps and the cache features.

We use callbacks partly because properties can vary at runtime (eg, through
access locks on registers) and partly because big switch statements are a
good compromise between readable code and small data size for providing
information on big register maps.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

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