clk: tegra: Avoid calling an uninitialized function

Commit 493ffb046cf5 ("clk: tegra: super: Switch to determine_rate")
replaced clk_super_round_rate() by clk_super_determine_rate(), but
didn't update one callsite that was explicitly calling the old
tegra_clk_super_ops.round_rate() function, which was now NULL. This
resulted in a crash on Tegra30 systems during early boot.

Switch this callsite over to the clk_super_determine_rate() equivalent
to avoid the crash.

Fixes: 493ffb046cf5 ("clk: tegra: super: Switch to determine_rate")
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230630130748.840729-1-thierry.reding@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: tegra: cclk: Handle thermal DIV2 CPU frequency throttling

Check whether thermal DIV2 throttle is active in order to report
the CPU frequency properly. This very useful for userspace tools
like cpufreq-info which show actual frequency asserted from hardware.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

clk: tegra: cclk: Add helpers for handling PLLX rate changes

CCLK should be re-parented away from PLLX if PLLX's rate is changing.
The PLLP parent is a common safe CPU parent for all Tegra SoCs, thus
CCLK will be re-parented to PLLP before PLLX rate-change begins and then
switched back to PLLX after the rate-change completion. This patch adds
helper functions which perform CCLK re-parenting, these helpers will be
utilized by further patches.

Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Marcel Ziswiler <marcel@ziswiler.com>
Tested-by: Jasper Korten <jja2000@gmail.com>
Tested-by: David Heidelberg <david@ixit.cz>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

clk: tegra: Add custom CCLK implementation

CCLK stands for "CPU Clock", CPU core is running off CCLK. CCLK supports
multiple parents, it has internal clock divider and a clock skipper.
PLLX is the main CCLK parent that provides clock rates above 1GHz and it
has special property such that the CCLK's internal divider is set into
bypass mode when PLLX is selected as a parent for CCLK.

This patch forks generic Super Clock into CCLK implementation which takes
into account all CCLK specifics. The proper CCLK implementation is needed
by the upcoming Tegra20 CPUFreq driver update that will allow to utilize
the generic cpufreq-dt driver by moving intermediate clock selection into
the clock driver.

Note that technically this patch could be squashed into clk-super.c, but
it is cleaner to have a separate source file. Also note that currently all
CCLKLP bits are left in the clk-super.c and only CCLKG is supported by
clk-tegra-super-cclk. It shouldn't be difficult to move the CCLKLP bits,
but CCLKLP is not used by anything in kernel and thus better not to touch
it for now.

Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Marcel Ziswiler <marcel@ziswiler.com>
Tested-by: Jasper Korten <jja2000@gmail.com>
Tested-by: David Heidelberg <david@ixit.cz>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>