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

Add support for parent_hw in system 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-system 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/20230615093227.576102-7-claudiu.beznea@microchip.com

clk: at91: mark ddr clocks as critical

Mark DDR clocks as critical for AT91 devices. These clocks are enabled
by bootloader when initializing DDR and needs to stay enabled. Up to
this patch the DDR clocks were requested from drivers/memory/atmel-sdramc.c
which does only clock request and enable. There is no need to have
a separate driver just for this, thus the atmel-sdramc.c will be deleted
in a subsequent patch.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20221208114515.35179-2-claudiu.beznea@microchip.com

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: 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>

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: 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: 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: remove IRQ handling and use polling

The AT91 clock drivers make use of IRQs to avoid polling when waiting for
some clocks to be enabled. Unfortunately, this leads to a crash when those
IRQs are threaded (which happens when using preempt-rt) because they are
registered before thread creation is possible.

Use polling on those clocks instead to avoid the problem.

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: system: don't try to free_irq when there is no IRQ

In the error path of at91_clk_register_system(), sys->irq is freed
unconditionally but it may not exist or be request at all.

Signed-off-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: do not leak resources

Do not leak memory and free irqs in case of an error.

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: David Dueck <davidcdueck@googlemail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

clk: at91: remove the useless CLK_IGNORE_UNUSED flag

The CLK_IGNORE_UNUSED flag was added on all the system clocks because of the
ddrck. Now that it is handled by the ram controller driver, we can drop it.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

clk: at91: fix programmable clk irq handling

The PCKRDY bit is not set until the system clock is enabled.
This patch moves the management of the ready status in the system clock
driver.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

clk: at91: propagate rate change on system clks

System clks are just gates, and thus do not provide any rate operations.
Authorize clk rate change to be propagated to system clk parents.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

clk: at91: add PMC system clocks

This patch adds new at91 system clock implementation using common clk
framework.

Some peripherals need to enable a "system" clock in order to work properly.
Each system clock is given an id based on the bit position in SCER/SCDR
registers.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>