Add support for clock gate hysteresis control.  For now, if it's
defined for a clock, it's enabled.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

Add support for CCU policy engine control, and also for setting the
mask bits for bus clocks that require a policy change to get
activated.  This includes adding validity checking framework for
CCUs, to validate the policy fields if defined.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

We know up front how many CCU's we'll support, so there's no need to
allocate their data structures dynamically.  Define a macro
KONA_CCU_COMMON() to simplify the initialization of many of the
fields in a ccu_data structure.  Pass the address of a statically
defined CCU structure to kona_dt_ccu_setup() rather than having that
function allocate one.

We also know at build time how many clocks a given CCU will provide,
though the number of of them for each CCU is different.  Record the
number of clocks we need in the CCU's clk_onecell_data struct
(which is used when we register the CCU with the common clock code
as a clock provider).  Rename that struct field "clk_data" (because
"data" alone gets a little confusing).

Use the known clock count to move the allocation of each CCU's
clocks array into ccu_clks_setup() rather than having each CCU's
setup callback function do it.

(The real motivation behind all of this is that we'll be doing some
static initialization of some additional CCU-specific data soon.)
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

Use the init_data.name field to hold the name of a Kona clock rather
than duplicating it.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

Don't let a failure of ccu_wait_bit() go unnoticed.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

The Broadcom Kona clock code, as originally written, made use of
unnamed union and struct fields.  This is a feature present in C11,
and is a GNU extension otherwise.  It worked very well for me.

Unfortunately, Russell King reported that this feature was not
supported in a build environment he used, which meant attempting
to build this code failed spectacularly.

Add names to these unnamed fields, and update the code accordingly.
Reported-by: NRussell King <linux@arm.linux.org.uk>
Tested-by: NMarkus Mayer <markus.mayer@linaro.org>
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

Add code for device tree support of clocks in the BCM281xx family of
SoCs.  Machines in this family use peripheral clocks implemented by
"Kona" clock control units (CCUs).  (Other Broadcom SoC families use
Kona style CCUs as well, but support for them is not yet upstream.)

A BCM281xx SoC has multiple CCUs, each of which manages a set of
clocks on the SoC.  A Kona peripheral clock is composite clock that
may include a gate, a parent clock multiplexor, and zero, one
or two dividers.  There is a variety of gate types, and many gates
implement hardware-managed gating (often called "auto-gating").
Most dividers divide their input clock signal by an integer value
(one or more).  There are also "fractional" dividers which allow
division by non-integer values.  To accomodate such dividers,
clock rates and dividers are generally maintained by the code in
"scaled" form, which allows integer and fractional dividers to
be handled in a uniform way.

If present, the gate for a Kona peripheral clock must be enabled
when a change is made to its multiplexor or one of its dividers.
Additionally, dividers and multiplexors have trigger registers which
must be used whenever the divider value or selected parent clock is
changed.  The same trigger is often used for a divider and
multiplexor, and a BCM281xx peripheral clock occasionally has two
triggers.

The gate, dividers, and parent clock selector are treated in this
code as "components" of a peripheral clock.  Their functionality is
implemented directly--e.g. the common clock framework gate
implementation is not used for a Kona peripheral clock gate.  (This
has being considered though, and the intention is to evolve this
code to leverage common code as much as possible.)

The source code is divided into three general portions:

    drivers/clk/bcm/clk-kona.h
    drivers/clk/bcm/clk-kona.c
        These implement the basic Kona clock functionality,
        including the clk_ops methods and various routines to
        manipulate registers and interpret their values.  This
        includes some functions used to set clocks to a desired
        initial state (though this feature is only partially
        implemented here).

    drivers/clk/bcm/clk-kona-setup.c
        This contains generic run-time initialization code for
        data structures representing Kona CCUs and clocks.  This
        encapsulates the clock structure initialization that can't
        be done statically.  Note that there is a great deal of
        validity-checking code here, making explicit certain
        assumptions in the code.   This is mostly useful for adding
        new clock definitions and could possibly be disabled for
        production use.

    drivers/clk/bcm/clk-bcm281xx.c
        This file defines the specific CCUs used by BCM281XX family
        SoCs, as well as the specific clocks implemented by each.
        It declares a device tree clock match entry for each CCU
        defined.

    include/dt-bindings/clock/bcm281xx.h
        This file defines the selector (index) values used to
        identify a particular clock provided by a CCU.  It consists
        entirely of C preprocessor constants, to be used by both the
        C source and device tree source files.
Signed-off-by: NAlex Elder <elder@linaro.org>
Reviewed-by: NTim Kryger <tim.kryger@linaro.org>
Reviewed-by: NMatt Porter <mporter@linaro.org>
Acked-by: NMike Turquette <mturquette@linaro.org>
Signed-off-by: NMatt Porter <mporter@linaro.org>