clk: renesas: Zero init clk_init_data

As clk_core_populate_parent_map() checks clk_init_data.num_parents
first, and checks clk_init_data.parent_names[] before
clk_init_data.parent_data[] and clk_init_data.parent_hws[], leaving the
latter uninitialized doesn't do harm for now. However, it is better to
play it safe, and initialize all clk_init_data structures to zeroes, to
avoid any current and future members containing uninitialized data.

Remove a few explicit zero initializers, which are now superfluous.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20210326105434.1574796-1-geert+renesas@glider.be

clk: renesas: rcar-gen2: Switch Z clock to .determine_rate()

As the .round_rate() callback returns a long clock rate, it cannot
return clock rates that do not fit in signed long, but do fit in
unsigned long. Hence switch the Z clock on R-Car Gen2 from the old
.round_rate() callback to the newer .determine_rate() callback, which
does not suffer from this limitation.

This includes implementing range checking.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20190830134515.11925-7-geert+renesas@glider.be

clk: renesas: rcar-gen2: Improve arithmetic divisions

- Use div64_ul() instead of div_u64() if the divisor is unsigned long,
to avoid truncation to 32-bit on 64-bit platforms,
- Prefer ULL constant suffixes over casts to u64,
- Prioritize multiplication over division, to increase accuracy.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20190830134515.11925-2-geert+renesas@glider.be

clk: renesas: Convert to SPDX identifiers

This patch updates license to use SPDX-License-Identifier
instead of verbose license text.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
[rebased against clk-spdx]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: renesas: rcar-gen2: Centralize quirks handling

Introduce centralized quirks handling like on R-Car Gen3, and convert
the RZ/G1C SD clock table handling over to it.

This makes it easier to add more quirks later, if/when needed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Biju Das <biju.das@bp.renesas.com>

clk: renesas: cpg-mssr: Add r8a77470 support

Add RZ/G1C (R8A77470) Clock Pulse Generator / Module Standby and Software
Reset support.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

clk: renesas: cpg-mssr: Add support to restore core clocks during resume

On R-Car Gen3 systems, PSCI system suspend powers down the SoC, possibly
losing clock configuration. Hence add a notifier chain that can be used
by core clocks to save/restore clock state during system suspend/resume.

The implementation of the actual clock state save/restore operations is
clock-specific, and to be registered with the notifier chain in the SoC
or family-specific cpg_mssr_info.cpg_clk_register() callback.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

clk: renesas: cpg-mssr: Add common R-Car Gen2 support

Add the common R-Car Gen2 (and RZ/G) Clock Pulse Generator / Module
Standby and Software Reset support code, using the CPG/MSSR driver
core.

Based on the proof-of-concept R8A7791 CPG/MSSR patch by Geert
Uytterhoeven <geert+renesas@glider.be>.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>