Components of the Versatile Express platform (configuration
microcontrollers on motherboard and daughterboards in particular)
talk to each other over a custom configuration bus. They
provide miscellaneous functions (from clock generator control
to energy sensors) which are represented as platform devices
(and Device Tree nodes). The transactions on the bus can
be generated by different "bridges" in the system, some
of which are universal for the whole platform (for the price
of high transfer latencies), others restricted to a subsystem
(but much faster).

Until now drivers for such functions were using custom "func"
API, which is being replaced in this patch by regmap calls.
This required:

* a rework (and move to drivers/bus directory, as suggested
  by Samuel and Arnd) of the config bus core, which is much
  simpler now and uses device model infrastructure (class)
  to keep track of the bridges; non-DT case (soon to be
  retired anyway) is simply covered by a special device
  registration function

* the new config-bus driver also takes over device population,
  so there is no need for special matching table for
  of_platform_populate nor "simple-bus" hack in the arm64
  model dtsi file (relevant bindings documentation has
  been updated); this allows all the vexpress devices
  fit into normal device model, making it possible
  to remove plenty of early inits and other hacks in
  the near future

* adaptation of the syscfg bridge implementation in the
  sysreg driver, again making it much simpler; there is
  a special case of the "energy" function spanning two
  registers, where they should be both defined in the tree
  now, but backward compatibility is maintained in the code

* modification of the relevant drivers:

  * hwmon - just a straight-forward API change
  * power/reset driver - API change
  * regulator - API change plus error handling
    simplification
  * osc clock driver - this one required larger rework
    in order to turn in into a standard platform driver
Signed-off-by: NPawel Moll <pawel.moll@arm.com>
Acked-by: NMark Brown <broonie@linaro.org>
Acked-by: NLee Jones <lee.jones@linaro.org>
Acked-by: NGuenter Roeck <linux@roeck-us.net>
Acked-by: NMike Turquette <mturquette@linaro.org>

Following arm64 commit bc3ee18a (arm64: init: Move of_clk_init to
time_init()), vexpress_osc_of_setup() is called via of_clk_init() long
before initcalls are issued. Initialising the vexpress oscillators
requires the vespress sysregs to be already initialised, so this patch
adds an explicit call to vexpress_sysreg_of_early_init() in vexpress
oscillator setup function.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Tested-by: NWill Deacon <will.deacon@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NPawel Moll <pawel.moll@arm.com>
Acked-by: NPawel Moll <pawel.moll@arm.com>
Cc: Mike Turquette <mturquette@linaro.org>

If the allocation fails then we dereference the NULL in the error path.
Just return directly.

Fixes: ed27ff1d ('clk: Versatile Express clock generators ("osc") driver')
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NPawel Moll <pawel.moll@arm.com>

Previously all the clocks were reported as "osc". Now it will be
something like "/dcc/osc@0".
Signed-off-by: NPawel Moll <pawel.moll@arm.com>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

Use common of_clk_init() function for clock initialization.
Signed-off-by: NPrashant Gaikwad <pgaikwad@nvidia.com>
Tested-by: NPawel Moll <pawel.moll@arm.com>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

This driver provides a common clock framework hardware driver
for Versatile Express clock generators (a.k.a "osc") controlled
via the config bus.
Signed-off-by: NPawel Moll <pawel.moll@arm.com>
Signed-off-by: NMike Turquette <mturquette@linaro.org>