pwm: bcm2835: Make use of devm_pwmchip_alloc() function

This prepares the pwm-bcm2835 driver to further changes of the pwm core
outlined in the commit introducing devm_pwmchip_alloc(). There is no
intended semantical change and the driver should behave as before.

Link: https://lore.kernel.org/r/441489772bdfbb2cd206fd534b36c63e8c50843a.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

pwm: bcm2835: Drop write-only member of driver private data

Since commit fcc760729359 ("pwm: bcm2835: Allow PWM driver to be used in
atomic context") struct bcm2835_pwm::dev is only assigned a value, but
it's never used. So the dev member can just be dropped.

Link: https://lore.kernel.org/r/20240129081029.2355612-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

pwm: bcm2835: Remove duplicate call to clk_rate_exclusive_put()

devm_add_action_or_reset() already calls the action in the error case.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Closes: https://lore.kernel.org/linux-pwm/fuku3b5ur6y4k4refd3vmeoenzjo6mwe3b3gtel34rhhhtvnsa@w4uktgbqsc3w/
Fixes: fcc760729359 ("pwm: bcm2835: Allow PWM driver to be used in atomic context")
Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20231222131312.174491-1-sean@mess.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

pwm: bcm2835: Allow PWM driver to be used in atomic context

clk_get_rate() may do a mutex lock. Fetch the clock rate once, and prevent
rate changes using clk_rate_exclusive_get().

Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Fix NPD in suspend/resume

When 119a508c4dc9 ("pwm: bcm2835: Add support for suspend/resume") was
sent out on October 11th,, there was still a call to
platform_set_drvdata() which would ensure that the driver private data
structure could be used in bcm2835_pwm_{suspend,resume}.

A cleanup now merged as commit commit 2ce7b7f6704c ("pwm: bcm2835:
Simplify using devm functions") removed that call which would now cause
a NPD in bcm2835_pwm_{suspend,resume} as a consequence.

Fixes: 119a508c4dc9 ("pwm: bcm2835: Add support for suspend/resume")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/linux-pwm/20231113164632.2439400-1-florian.fainelli@broadcom.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

pwm: bcm2835: Add support for suspend/resume

Similar to other drivers, we need to make sure that the clock is
disabled during suspend and re-enabled during resume.

Reported-by: Angus Clark <angus.clark@broadcom.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Simplify using devm functions

With devm_clk_get_enabled() the call to clk_disable_unprepare() can be
dropped from the error path and the remove callback. With
devm_pwmchip_add() pwmchip_remove() can be dropped. Then the remove
callback is empty and can go away, too. With bcm2835_pwm_remove() the only
user of platform_get_drvdata() is gone and so platform_set_drvdata() can
be dropped from .probe(), too.

Also use dev_err_probe() for simplified (and improved) error reporting.

Link: https://lore.kernel.org/r/20230929161918.2410424-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: Manage owner assignment implicitly for drivers

Instead of requiring each driver to care for assigning the owner member
of struct pwm_ops, handle that implicitly using a macro. Note that the
owner member has to be moved to struct pwm_chip, as the ops structure
usually lives in read-only memory and so cannot be modified.

The upside is that new low level drivers cannot forget the assignment and
save one line each. The pwm-crc driver didn't assign .owner, that's not
a problem in practice though as the driver cannot be compiled as a
module.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # Intel LPSS
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com> # pwm-{bcm,brcm}*.c
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com> # sun4i
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> # pwm-visconti
Acked-by: Heiko Stuebner <heiko@sntech.de> # pwm-rockchip
Acked-by: Michael Walle <michael@walle.cc> # pwm-sl28cpld
Acked-by: Neil Armstrong <neil.armstrong@linaro.org> # pwm-meson
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230804142707.412137-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: Simplify all drivers with explicit of_pwm_n_cells = 3

With the previous commit there is no need for the lowlevel driver any
more to specify it it uses two or three cells. So simplify accordingly.

The only non-trival change affects the pwm-rockchip driver: It used to only
support three cells if the hardware supports polarity. Now the default
number depends on the device tree which has to match hardware anyhow
(and if it doesn't the error is just a bit delayed as a PWM handle with
an inverted setting is catched when pwm_apply_state() is called).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Free resources only after pwmchip_remove()

Before pwmchip_remove() returns the PWM is expected to be functional. So
remove the pwmchip before disabling the clock.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: Always allocate PWM chip base ID dynamically

Since commit 5e5da1e9fbee ("pwm: ab8500: Explicitly allocate pwm chip
base dynamically") all drivers use dynamic ID allocation explicitly. New
drivers are supposed to do the same, so remove support for driver
specified base IDs and drop all assignments in the low-level drivers.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Improve period and duty cycle calculation

With an input clk rate bigger than 2000000000, scaler would have been
zero which then would have resulted in a division by zero.

Also the originally implemented algorithm divided by the result of a
division. This nearly always looses precision. Consider a requested period
of 1000000 ns. With an input clock frequency of 32786885 Hz the hardware
was configured with an actual period of 983869.007 ns (PERIOD = 32258)
while the hardware can provide 1000003.508 ns (PERIOD = 32787).
And note if the input clock frequency was 32786886 Hz instead, the hardware
was configured to 1016656.477 ns (PERIOD = 33333) while the optimal
setting results in 1000003.477 ns (PERIOD = 32787).

This patch implements proper range checking and only divides once for
the calculation of period (and similar for duty_cycle).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Tested-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Support apply function for atomic configuration

Use the newer .apply function of pwm_ops instead of .config, .enable,
.disable and .set_polarity. This guarantees atomic changes of the pwm
controller configuration. It also reduces the size of the driver.

Since now period is a 64 bit value, add an extra check to reject periods
that exceed the possible max value for the 32 bit register.

This has been tested on a Raspberry PI 4.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Convert to devm_platform_ioremap_resource()

Use devm_platform_ioremap_resource() to simplify code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Simplify with dev_err_probe()

Common pattern of handling deferred probe can be simplified with
dev_err_probe(). Less code and also it prints the error value.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Dynamically allocate base

The newer 2711 and 7211 chips have two PWM controllers and failure to
dynamically allocate the PWM base would prevent the second PWM
controller instance being probed for succeeding with an -EEXIST error
from alloc_pwms().

Fixes: e5a06dc5ac1f ("pwm: Add BCM2835 PWM driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Suppress error message during deferred probe

This suppresses error messages in case the PWM clock isn't ready yet.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Fix period_ns range check

The range check for period_ns was written under assumption of a fixed
PWM clock. With clk-bcm2835 driver the PWM clock is a dynamic one.
So fix this by doing the range check on the period register value.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Suppress error message for invalid period_ns

The PWM config can be triggered via sysfs, so we better suppress the
error message in case of an invalid period to avoid kernel log spamming.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Improve precision of PWM

If sending IR with carrier of 455kHz using the pwm-ir-tx driver, the
carrier ends up being 476kHz. The clock is set to bcm2835-pwm with a
rate of 10MHz.

A carrier of 455kHz has a period of 2198ns, but the arithmetic truncates
this to 2100ns rather than 2200ns. So, use DIV_ROUND_CLOSEST() to reduce
rounding errors, and we have a much more accurate carrier of 454.5kHz.

Reported-by: Andreas Christ <andreas@christ-faesch.ch>
Signed-off-by: Sean Young <sean@mess.org>
Acked-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Switch to SPDX identifier

Adopt the SPDX license identifier headers to ease license compliance
management.

Cc: Bart Tanghe <bart.tanghe@thomasmore.be>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Support for polarity setting via DT

This adds support for the third (optional) pwm cell to specify the
polarity, which is needed by display backlights for example.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Fix email address specification

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Prevent division by zero

It's possible that the PWM clock becomes an orphan. So better check the
result of clk_get_rate() in order to prevent a division by zero.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: bcm2835: Calculate scaler in ->config()

Currently pwm-bcm2835 assumes a fixed clock rate and stores the
resulting scaler in the driver structure. But with the upcoming
PWM clock support for clk-bcm2835 the rate could change, so
calculate the scaler in the ->config() callback.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

pwm: Add BCM2835 PWM driver

Add PWM driver for Broadcom BCM2835 processor (Raspberry Pi)

Signed-off-by: Bart Tanghe <bart.tanghe@thomasmore.be>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>