clk: at91: clk-generated: add support for parent_hw

Add support for parent_hw in generic clock drivers.
With this parent-child relation is described with pointers rather
than strings making registration a bit faster.

All the SoC based drivers that rely on clk-generated were adapted
to the new API change. The switch itself for SoCs will be done
in subsequent patches.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20230615093227.576102-3-claudiu.beznea@microchip.com

clk: Stop forwarding clk_rate_requests to the parent

If the clock cannot modify its rate and has CLK_SET_RATE_PARENT,
clk_mux_determine_rate_flags(), clk_core_round_rate_nolock() and a
number of drivers will forward the clk_rate_request to the parent clock.

clk_core_round_rate_nolock() will pass the pointer directly, which means
that we pass a clk_rate_request to the parent that has the rate,
min_rate and max_rate of the child, and the best_parent_rate and
best_parent_hw fields will be relative to the child as well, so will
point to our current clock and its rate. The most common case for
CLK_SET_RATE_PARENT is that the child and parent clock rates will be
equal, so the rate field isn't a worry, but the other fields are.

Similarly, if the parent clock driver ever modifies the best_parent_rate
or best_parent_hw, this will be applied to the child once the call to
clk_core_round_rate_nolock() is done. best_parent_hw is probably not
going to be a valid parent, and best_parent_rate might lead to a parent
rate change different to the one that was initially computed.

clk_mux_determine_rate_flags() and the affected drivers will copy the
request before forwarding it to the parents, so they won't be affected
by the latter issue, but the former is still going to be there and will
lead to erroneous data and context being passed to the various clock
drivers in the same sub-tree.

Let's create two new functions, clk_core_forward_rate_req() and
clk_hw_forward_rate_request() for the framework and the clock providers
that will copy a request from a child clock and update the context to
match the parent's. We also update the relevant call sites in the
framework and drivers to use that new function.

Let's also add a test to make sure we avoid regressions there.

Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com> # imx8mp
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> # exynos4210, meson g12b
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220816112530.1837489-22-maxime@cerno.tech
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: generated: consider range when calculating best rate

clk_generated_best_diff() helps in finding the parent and the divisor to
compute a rate closest to the required one. However, it doesn't take into
account the request's range for the new rate. Make sure the new rate
is within the required range.

Fixes: 8a8f4bf0c480 ("clk: at91: clk-generated: create function to find best_diff")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Link: https://lore.kernel.org/r/20220413071318.244912-1-codrin.ciubotariu@microchip.com
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: re-factor clocks suspend/resume

SAMA5D2 and SAMA7G5 have a special power saving mode (backup mode) where
most of the SoC's components are powered off (including PMC). Resuming
from this mode is done with the help of bootloader. Peripherals are not
aware of the power saving mode thus most of them are disabling clocks in
proper suspend API and re-enable them in resume API without taking into
account the previously setup rate. Moreover some of the peripherals are
acting as wakeup sources and are not disabling the clocks in this
scenario, when suspending. Since backup mode cuts the power for
peripherals, in resume part these clocks needs to be re-configured.

The initial PMC suspend/resume code was designed only for SAMA5D2's PMC
(as it was the only one supporting backup mode). SAMA7G supports also
backup mode and its PMC is different (few new functionalities, different
registers offsets, different offsets in registers for each
functionalities). To address both SAMA5D2 and SAMA7G5 PMC add
.save_context()/.resume_context() support to each clocks driver and call
this from PMC driver.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-2-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: clk-generated: Limit the requested rate to our range

On clk_generated_determine_rate(), the requested rate could be outside
of clk's range. Limit the rate to the clock's range to not return an
error.

Fixes: df70aeef6083 ("clk: at91: add generated clock driver")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Link: https://lore.kernel.org/r/20210707131213.3283509-1-codrin.ciubotariu@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: clk-generated: add mux_table option

Add mux table option. This is necessary for IP versions that has
gaps in the range of available clock sources (e.g. SAMA7G5).

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/1595403506-8209-12-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: clk-generated: pass the id of changeable parent at registration

Pass the ID of changeable parent at registration. This will allow
the scalability of this clock driver with regards to the changeable
parent ID for versions of this IP where changeable parent is not the
last one in the parents list (e.g. SAMA7G5). With this the clock flags
are set to zero in case we have no changeable parent. Also in
clk_generated_best_diff() the *best_diff variable is check against
tmp_diff variable using ">=" operator instead of ">" so that in case
the requested frequency could be obtained using fix parents + gck
dividers but the clock also supports changeable parent to be able
to force the usage of the changeable parent.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/1595403506-8209-11-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: replace conditional operator with double logical not

Replace conditional operator with double logical not as code
may be simpler to read.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/1595403506-8209-10-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: clk-generated: check best_rate against ranges

Check best_rate against available clock ranges.

Fixes: df70aeef6083 ("clk: at91: add generated clock driver")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1595403506-8209-3-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: clk-generated: continue if __clk_determine_rate() returns error

__clk_determine_rate() may return error. Skip the current step
in case of error.

Fixes: 1a1a36d72e3d3 ("clk: at91: clk-generated: make gclk determine audio_pll rate")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1595403506-8209-2-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: generated: Truncate divisor to GENERATED_MAX_DIV + 1

In clk_generated_determine_rate(), if the divisor is greater than
GENERATED_MAX_DIV + 1, then the wrong best_rate will be returned.
If clk_generated_set_rate() will be called later with this wrong
rate, it will return -EINVAL, so the generated clock won't change
its value. Do no let the divisor be greater than GENERATED_MAX_DIV + 1.

Fixes: 8c7aa6328947 ("clk: at91: clk-generated: remove useless divisor loop")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

clk: at91: allow configuring generated PCR layout

The PCR register layout for GCLKCSS is changing for the future SoCs, allow
configuring it.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: move DT compatibility code to its own file

Move all the DT backward compatibility code to its own file so it can be
deleted later.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: allow clock registration from C code

Remove static keyword to allow functions to be used from other units. Also
move some struct and function declarations to pmc.h

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
[sboyd@kernel.org: Include pmc.h]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: generated: set audio_pll_allowed in at91_clk_register_generated()

Set gck->audio_pll_allowed in at91_clk_register_generated. This makes it
easier to do it from code that is not parsing device tree.

Also, this fixes an issue where the resulting clk_hw can be dereferenced
before being tested for error.

Fixes: 1a1a36d72e3d ("clk: at91: clk-generated: make gclk determine audio_pll rate")
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: generated: SSCs don't have a gclk

As the SSCs don't have gclk, don't check for their ID to allow them to set
the audio pll rate.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: at91: clk-generated: make gclk determine audio_pll rate

This allows gclk to determine audio_pll rate and set the parent rate
accordingly.

However, there are multiple children clocks that could technically
change the rate of audio_pll (via gck). With the rate locking, the first
consumer to enable the clock will be the one definitely setting the rate
of the clock.

Since audio IPs are most likely to request the same rate, we enforce
that the only clks able to modify gck rate are those of audio IPs.

To remain consistent, we deny other clocks to be children of audio_pll.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: clk-generated: create function to find best_diff

The way to find the best_diff and do the appropriate process afterwards
can be re-used.

This patch prepares the driver for an upcoming patch that will allow
clk_generated to determine the rate of the audio_pll.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: clk-generated: remove useless divisor loop

The driver requests the current clk rate of each of its parent clocks to
decide whether a clock rate is suitable or not. It does not request
determine_rate from a parent clock which could request a rate change in
parent clock (i.e. there is no parent rate propagation).

We know the rate we want (passed along req argument of the function) and
the parent clock rate, thus we know the closest rounded divisor, we
don't need to iterate over the available divisors to find the best one
for a given clock.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: Add sama5d2 suspend/resume

On sama5d2, VDD core maybe be cut while in suspend. This means registers
will be lost. Ensure they are saved and restored properly.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: fix clk-generated compilation

Fix missing }

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: fix clk-generated parenting

clk_generated_startup is called after clk_hw_register. So the first call to
get_parent will not have the correct value (i.e. 0) and because this is
cached, it may never be updated.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Fixes: df70aeef6083 ("clk: at91: add generated clock driver")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: Migrate to clk_hw based registration and OF APIs

Now that we have clk_hw based provider APIs to register clks, we
can get rid of struct clk pointers in this driver, allowing us to
move closer to a clear split of consumer and provider clk APIs.

Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Tested-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: make of_sama5d2_clk_generated_setup() static

The of_sama5d2_clk_generated_setup() is not exported outside
of the driver, so make it static to fix the warning about it
being not static:

drivers/clk/at91/clk-generated.c:270:13: warning: symbol 'of_sama5d2_clk_generated_setup' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: Remove impossible checks for of_clk_get_parent_count()

These checks for < 0 are impossible now that
of_clk_get_parent_count() returns an unsigned int. Change the
checks for == 0 and update the type.

Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: remove useless includes

Over time, some includes were copy pasted from other clocks drivers but are
not necessary.

Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

clk: at91: make use of syscon/regmap internally

Use the regmap coming from syscon to access the registers instead of using
pmc_read/pmc_write. This allows to avoid passing the at91_pmc structure to
the child nodes of the PMC.

The final benefit is to have each clock register itself instead of having
to iterate over the children.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

clk: at91: add generated clock driver

Add a new type of clocks that can be provided to a peripheral.
In addition to the peripheral clock, this new clock that can use several
input clocks as parents can generate divided rates.
This would allow a peripheral to have finer grained clocks for generating
a baud rate, clocking an asynchronous part or having more
options in frequency.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[sboyd@codeaurora.org: Transition to new clk_hw provider APIs]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>