clk: migrate to SPDX-License-Identifier use ...

Some of these are a product of source sync with Linux, the other were
done with macro assistance by searching for /later/, deleting license text,
adding appropriate SPDX-License-Identifier and manual post-review.

Devices without a license indicated where assumed GPL-2.0-only according
with the project's license.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: implement clk_register_fixed_rate ...

We lack a way to instantiate a fixed clock while specifying a parent.
This is used in the at91 clock code sync with upstream in a later
commit, so prepare by porting clk_register_fixed_rate.

It's based on the Linux commit of the same name with the difference that
it doesn't use (and thus doesn't require) a struct device_d * as first
parameter.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: No-op CLK_OF_DECLARE if not enabled ...

Instead of wrapping each defenition of CLK_OF_DECLARE hook with
preprocessor guards, change the definition of CLK_OF_DECLARE to expand
into no-op if COMMON_CLK_OF_PROVIDER is not enabled.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: Make COMMON_CLK_OF_PROVIDER depend on OFTREE ...

Make COMMON_CLK_OF_PROVIDER depend on OFTREE, this way checking for:

	defined(CONFIG_OFTREE) && defined(CONFIG_COMMON_CLK_OF_PROVIDER)

can be simplified to just:

	defined(CONFIG_COMMON_CLK_OF_PROVIDER)

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/clk/clk-fixed.c: Fix sparse warning ...

drivers/clk/clk-fixed.c:35:16: warning: symbol 'clk_fixed_ops' was not declared. Should it be static?

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: fixed: add DT init function ...

This adds a DT init function to clk-fixed and corresponding CLK_OF_DECLARE
to put it into the DT clock provider table.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: Add is_enabled callback ...

This allows us to better detect whether a clk is enabled or not.

- If we can ask a clk, ask it. If it's enabled, go on and ask parents
- If we can't ask it, but it can be enabled, depend on the enable_count.
  if it's positive, go on and ask parents
- If we can't ask it and it cannot be enabled, assume it is enabled
  and ask parents.

This makes the CLK_ALWAYS_ENABLED unnecessary, since the fixed clk now
always returns 1 in its is_enabled callback.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: use the 'CLK_ALWAYS_ENABLED' flag for clk-fixed by default ...

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

clk: initial common clk support ...

This adds barebox common clk support loosely based on the Kernel common
clk support. differences are:

- barebox does not need prepare/unprepare
- no parent rate propagation for set_rate
- struct clk is not really encapsulated from the drivers

Along with the clk support we have support for some basic clk building
blocks:

- clk-fixed
- clk-fixed-factor
- clk-mux
- clk-divider

clk-fixed and clk-fixed-factor are completely generic, clk-mux and clk-divider
are currently the way i.MX muxes/dividers are implemented.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>