Generic I2C and SPI register map library

Many I2C and SPI based devices implement register maps on top of the raw wire interface. This is generally done in a very standard fashion by devices, resulting in a lot of very similar code in drivers. For some time now ASoC has factored this code out into the subsystem but that's only useful for audio devices. The intention with this series is to generalise the concept so that it can be used throughout the kernel.

It's not intended that this be suitable for all devices - some devices have things that are hard to generalise like registers with variable size and paging which are hard to support genericly. At the minute the code is focused on the common cases. It is likely that the same code could be used with other buses with similar properties to I2C and SPI.

Currently only physical I/O is handled, the intention is that once this support has been reviewed and merged the generic register cache code that ASoC includes will also be factored out too. For devices with read heavy workloads (especially those that need a lot of read/modify/write cycles) or which don't support read at all this can provide a useful performance improvement and for sparse register maps there's a lot of benefit in relatively complex cache code.

I'm not entirely happy with the implementation currently but am fairly happy with the external interfaces.

A semi-random set of driver conversions have been included in the series with various degrees of testing including the subsystem wide ASoC code. Far more drivers could use the code, these have mostly just been done as samples in a minimally invasive fashion.

There's a git branch at:

git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git for-next

but due to various -next dependencies this does not currently include all of the patches posted here. I've also created a regmap-asoc branch there which merges current ASoC code with the regmap code.

 MAINTAINERS                            |    7 +
 drivers/Kconfig                        |    1 +
 drivers/Makefile                       |    1 +
 drivers/mfd/Kconfig                    |    4 +
 drivers/mfd/pcf50633-core.c            |  114 ++------
 drivers/mfd/wm831x-core.c              |   97 +++----
 drivers/mfd/wm831x-i2c.c               |   56 ----
 drivers/mfd/wm831x-spi.c               |   48 ----
 drivers/mfd/wm8994-core.c              |  175 ++----------
 drivers/regmap/Kconfig                 |    6 +
 drivers/regmap/Makefile                |    3 +
 drivers/regmap/regmap-i2c.c            |  112 ++++++++
 drivers/regmap/regmap-spi.c            |   75 +++++
 drivers/regmap/regmap.c                |  478 ++++++++++++++++++++++++++++++++
 drivers/regulator/Kconfig              |    1 +
 drivers/regulator/tps65023-regulator.c |   98 ++-----
 include/linux/mfd/pcf50633/core.h      |    3 +-
 include/linux/mfd/wm831x/core.h        |    7 +-
 include/linux/mfd/wm8994/core.h        |    9 +-
 include/linux/regmap.h                 |   75 +++++
 include/sound/soc.h                    |    2 +
 sound/soc/Kconfig                      |    1 +
 sound/soc/soc-io.c                     |  316 ++-------------------
 23 files changed, 920 insertions(+), 769 deletions(-)