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>
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>