clk: ingenic: tcu: Switch to determine_rate

The Ingenic TCU clocks implements a mux with a set_parent hook, but
doesn't provide a determine_rate implementation.

This is a bit odd, since set_parent() is there to, as its name implies,
change the parent of a clock. However, the most likely candidate to
trigger that parent change is a call to clk_set_rate(), with
determine_rate() figuring out which parent is the best suited for a
given rate.

The other trigger would be a call to clk_set_parent(), but it's far less
used, and it doesn't look like there's any obvious user for that clock.

So, the set_parent hook is effectively unused, possibly because of an
oversight. However, it could also be an explicit decision by the
original author to avoid any reparenting but through an explicit call to
clk_set_parent().

The driver does implement round_rate() though, which means that we can
change the rate of the clock, but we will never get to change the
parent.

However, It's hard to tell whether it's been done on purpose or not.

Since we'll start mandating a determine_rate() implementation, let's
convert the round_rate() implementation to a determine_rate(), which
will also make the current behavior explicit. And if it was an
oversight, the clock behaviour can be adjusted later on.

Cc: Paul Cercueil <paul@crapouillou.net>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-60-971d5077e7d2@cerno.tech
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: ingenic-tcu: Properly enable registers before accessing timers

Access to registers is guarded by ingenic_tcu_{enable,disable}_regs()
so the stop bit can be cleared before accessing a timer channel, but
those functions did not clear the stop bit on SoCs with a global TCU
clock gate.

Testing on the X1000 has revealed that the stop bits must be cleared
_and_ the global TCU clock must be ungated to access timer registers.
This appears to be the norm on Ingenic SoCs, and is specified in the
documentation for the X1000 and numerous JZ47xx SoCs.

If the stop bit isn't cleared, register writes don't take effect and
the system can be left in a broken state, eg. the watchdog timer may
not run.

The bug probably went unnoticed because stop bits are zeroed when
the SoC is reset, and the kernel does not set them unless a timer
gets disabled at runtime. However, it is possible that a bootloader
or a previous kernel (if using kexec) leaves the stop bits set and
we should not rely on them being cleared.

Fixing this is easy: have ingenic_tcu_{enable,disable}_regs() always
clear the stop bit, regardless of the presence of a global TCU gate.

Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Paul Cercueil <paul@crapouillou.net>
Fixes: 4f89e4b8f121 ("clk: ingenic: Add driver for the TCU clocks")
Cc: stable@vger.kernel.org
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20220617122254.738900-1-aidanmacdonald.0x0@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

The TCU clock gate on X1000 wasn't requested by the driver and could
be gated automatically later on in boot, which prevents timers from
running and breaks PWM.

Add a workaround to support old device trees that don't specify the
"tcu" clock gate. In this case the kernel will print a warning and
attempt to continue without the clock, which is wrong, but it could
work if "clk_ignore_unused" is in the kernel arguments.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20220412122750.279058-3-aidanmacdonald.0x0@gmail.com
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: ingenic: Add support for the JZ4760

Add the CGU code and the compatible string to the TCU driver to support
the JZ4760 SoC.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210530164923.18134-7-paul@crapouillou.net
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: ingenic: Mark ingenic_tcu_of_match as __maybe_unused

This device id table is passed to of_match_node() later on in probe, but
on CONFIG_OF=n builds of_match_node() doesn't do anything with the
arguments. Lets just mark the table unused so that the compiler doesn't
complain about this.

drivers/clk/ingenic/tcu.c:326:34: warning: unused variable 'ingenic_tcu_of_match' [-Wunused-const-variable]
static const struct of_device_id ingenic_tcu_of_match[] __initconst = {
^
1 warning generated.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20200528233837.70269-1-sboyd@kernel.org

clk: ingenic/TCU: Fix round_rate returning error

When requesting a rate superior to the parent's rate, it would return
-EINVAL instead of simply returning the parent's rate like it should.

Fixes: 4f89e4b8f121 ("clk: ingenic: Add driver for the TCU clocks")
Cc: stable@vger.kernel.org
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lkml.kernel.org/r/20200213161952.37460-2-paul@crapouillou.net
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: Ingenic: Add support for TCU of X1000.

X1000 has a different TCU, since X1000 OST has been independent of TCU.
This patch is add TCU support of X1000, and prepare for later OST driver.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Link: https://lkml.kernel.org/r/1584457893-40418-3-git-send-email-zhouyanjie@wanyeetech.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk: convert VL struct to struct_size

There are a few manually-calculated variable-length struct allocations
left, this converts them to use struct_size. Found with the following
git grep command

git grep -A1 'kzalloc.*sizeof[^_].*+'

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lkml.kernel.org/r/20190927185110.29897-1-steve@sk2.org
Acked-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
[sboyd@kernel.org: Add grep command]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: ingenic: Add driver for the TCU clocks

Add driver to support the clocks provided by the Timer/Counter Unit
(TCU) of the JZ47xx SoCs from Ingenic.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Mathieu Malaterre <malat@debian.org>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: od@zcrc.me