The WFHWSIZE constant defines the maximum size for the hardware-specific
waveform representation buffer. It is currently local to
drivers/pwm/core.c, which makes it inaccessible to external tools like
bindgen.
Move the constant to include/linux/pwm.h to make it part of the public
API. As part of this change, rename it to PWM_WFHWSIZE to follow
standard kernel conventions for namespacing macros in public headers.
This allows bindgen to automatically generate a corresponding constant
for the Rust PWM abstractions, ensuring the value remains synchronized
between the C core and Rust code and preventing future maintenance
issues.
Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Link: https://lore.kernel.org/r/20250702-rust-next-pwm-working-fan-for-sending-v7-1-67ef39ff1d29@samsung.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
With this change each pwmchip defining the new-style waveform callbacks
can be accessed from userspace via a character device. Compared to the
sysfs-API this is faster and allows to pass the whole configuration in a
single ioctl allowing atomic application and thus reducing glitches.
On an STM32MP13 I see:
root@DistroKit:~ time pwmtestperf
real 0m 1.27s
user 0m 0.02s
sys 0m 1.21s
root@DistroKit:~ rm /dev/pwmchip0
root@DistroKit:~ time pwmtestperf
real 0m 3.61s
user 0m 0.27s
sys 0m 3.26s
pwmtestperf does essentially:
for i in 0 .. 50000:
pwm_set_waveform(duty_length_ns=i, period_length_ns=50000, duty_offset_ns=0)
and in the presence of /dev/pwmchip0 is uses the ioctls introduced here,
without that device it uses /sys/class/pwm/pwmchip0.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/ad4a4e49ae3f8ea81e23cac1ac12b338c3bf5c5b.1746010245.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Commit 9dd42d019e ("pwm: Allow pwm state transitions from an invalid
state") intended to allow some state transitions that were not allowed
before. The idea is sane and back then I also got the code comment
right, but the check for enabled is bogus. This resulted in state
transitions for enabled states to be allowed to have invalid duty/period
settings and thus it can happen that low-level drivers get requests for
invalid states🙄.
Invert the check to allow state transitions for disabled states only.
Fixes: 9dd42d019e ("pwm: Allow pwm state transitions from an invalid state")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250704172416.626433-2-u.kleine-koenig@baylibre.com
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
While telling the caller of pwm_set_waveform_might_sleep() if the
request was completed by rounding down only or (some) rounding up gives
additional information, it makes usage this function needlessly hard and
the additional information is not used. A prove for that is that
currently both users of this function just pass the returned value up to
their caller even though a positive value isn't intended there.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/528cc3bbd9e35dea8646b1bcc0fbfe6c498bb4ed.1746010245.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Up to now pwm_set_waveform_might_sleep() returned 1 for exact requests
that couldn't be served exactly. In contrast to
pwm_round_waveform_might_sleep() and pwm_set_waveform_might_sleep() with
exact = false this is an error condition. So simplify handling for
callers of pwm_set_waveform_might_sleep() by returning -EDOM instead of
1 in this case.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20538a46719584dafd8a1395c886780a97dcdf79.1746010245.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Add Return and (where interesting) Context sections, fix some formatting
and drop documenting the internal function __pwm_apply().
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250417181611.2693599-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Better explain how pwm_round_waveform_might_sleep() (and so the
respective lowlevel driver callback) is supposed to round and the
meaning of the return value.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/db84abf1e82e4498fc0e7c318d2673771d0039fe.1744120697.git.ukleinek@kernel.org
[ukleinek: Fix a rst formatting issue reported by Stephen Rothwell]
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
The .round_waveform_tohw() is supposed to return 0 if the request could
be rounded down to match the hardware capabilities and return 1 if
rounding down wasn't possible.
Expand the PWM_DEBUG check to not only assert proper downrounding if 0
was returned but also check that it was actually rounded up when the
callback signalled uprounding.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/dfb824ae37f99df068c752d48cbd163c044a74fb.1743844730.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Traditionally /sys/kernel/debug/pwm only contained info from pwm->state.
Most of the time this data represents the last requested setting which
might differ considerably from the actually configured in hardware
setting.
Expand the information in the debugfs file with the actual values.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/20250404104844.543479-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Waveform parameters are supposed to be rounded down to the next value
possible for the hardware. However when a requested value is too small,
.round_waveform_tohw() is supposed to pick the next bigger value and
return 1. Let pwm_set_waveform() behave in the same way.
This creates consistency between pwm_set_waveform_might_sleep() with
exact=false and pwm_round_waveform_might_sleep() +
pwm_set_waveform_might_sleep() with exact=true.
The PWM_DEBUG rounding check has to be adapted to only trigger if no
uprounding happend.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/353dc6ae31be815e41fd3df89c257127ca0d1a09.1743844730.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Platforms can have a standardized connector/expansion slot that exposes
signals like PWMs to expansion boards in an SoC agnostic way.
The support for nexus node [1] has been added to handle those cases in
commit bd6f2fd5a1 ("of: Support parsing phandle argument lists through
a nexus node"). This commit introduced of_parse_phandle_with_args_map()
to handle nexus nodes in a generic way and the gpio subsystem adopted
the support in commit c11e6f0f04 ("gpio: Support gpio nexus dt
bindings").
A nexus node allows to remap a phandle list in a consumer node through a
connector node in a generic way. With this remapping supported, the
consumer node needs to knwow only about the nexus node. Resources behind
the nexus node are decoupled by the nexus node itself.
This is particularly useful when this consumer is described in a
device-tree overlay. Indeed, to have the exact same overlay reused with
several base systems the overlay needs to known only about the connector
is going to be applied to without any knowledge of the SoC (or the
component providing the resource) available in the system.
As an example, suppose 3 PWMs connected to a connector. The connector
PWM 0 and 2 comes from the PWM 1 and 3 of the pwm-controller1. The
connector PWM 1 comes from the PWM 4 of the pwm-controller2. An
expansion device is connected to the connector and uses the connector
PMW 1.
Nexus node support in PWM allows the following description:
soc {
soc_pwm1: pwm-controller1 {
#pwm-cells = <3>;
};
soc_pwm2: pwm-controller2 {
#pwm-cells = <3>;
};
};
connector: connector {
#pwm-cells = <3>;
pwm-map = <0 0 0 &soc_pwm1 1 0 0>,
<1 0 0 &soc_pwm2 4 0 0>,
<2 0 0 &soc_pwm1 3 0 0>;
pwm-map-mask = <0xffffffff 0x0 0x0>;
pwm-map-pass-thru = <0x0 0xffffffff 0xffffffff>;
};
expansion_device {
pwms = <&connector 1 57000 0>;
};
>From the expansion device point of view, the PWM requested is the PWM 1
available at the connector regardless of the exact PWM wired to this
connector PWM 1. Thanks to nexus node remapping described at connector
node, this PWM is the PWM 4 of the pwm-controller2.
The nexus node remapping handling consists in handling #pwm-cells,
pwm-map, pwm-map-mask and pwm-map-pass-thru properties. This is already
supported by of_parse_phandle_with_args_map() thanks to its stem_name
parameter.
Add support for nexus node device-tree binding and the related remapping
in the PWM subsystem by simply using of_parse_phandle_with_args_map()
instead of of_parse_phandle_with_args().
[1] https://github.com/devicetree-org/devicetree-specification/blob/v0.4/source/chapter2-devicetree-basics.rst#nexus-nodes-and-specifier-mapping
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20250205095547.536083-3-herve.codina@bootlin.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
The PWM chip on PXA only has a single output. Back when the device tree
binding was defined it was considered a good idea to not pass the PWM
line index as is done for all other PWM types as it would be always zero
anyhow and so doesn't add any value.
However for consistency reasons it is nice when all PWMs use the same
binding. For that reason let of_pwm_single_xlate() (i.e. the function
that implements the PXA behaviour) behave in the same way as
of_pwm_xlate_with_flags() for 3 (or more) parameters. With that in
place, the pxa-pwm binding can be updated to #pwm-cells = <3> without
breaking old device trees that stick to #pwm-cells = <1>.
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Tested-by: Duje Mihanović <duje.mihanovic@skole.hr>
Reviewed-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/b33a84d3f073880e94fc303cd32ebe095eb5ce46.1738842938.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Here is the big set of driver core and debugfs updates for 6.14-rc1.
It's coming late in the merge cycle as there are a number of merge
conflicts with your tree now, and I wanted to make sure they were
working properly. To resolve them, look in linux-next, and I will send
the "fixup" patch as a response to the pull request.
Included in here is a bunch of driver core, PCI, OF, and platform rust
bindings (all acked by the different subsystem maintainers), hence the
merge conflict with the rust tree, and some driver core api updates to
mark things as const, which will also require some fixups due to new
stuff coming in through other trees in this merge window.
There are also a bunch of debugfs updates from Al, and there is at least
one user that does have a regression with these, but Al is working on
tracking down the fix for it. In my use (and everyone else's linux-next
use), it does not seem like a big issue at the moment.
Here's a short list of the things in here:
- driver core bindings for PCI, platform, OF, and some i/o functions.
We are almost at the "write a real driver in rust" stage now,
depending on what you want to do.
- misc device rust bindings and a sample driver to show how to use
them
- debugfs cleanups in the fs as well as the users of the fs api for
places where drivers got it wrong or were unnecessarily doing things
in complex ways.
- driver core const work, making more of the api take const * for
different parameters to make the rust bindings easier overall.
- other small fixes and updates
All of these have been in linux-next with all of the aforementioned
merge conflicts, and the one debugfs issue, which looks to be resolved
"soon".
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core and debugfs updates from Greg KH:
"Here is the big set of driver core and debugfs updates for 6.14-rc1.
Included in here is a bunch of driver core, PCI, OF, and platform rust
bindings (all acked by the different subsystem maintainers), hence the
merge conflict with the rust tree, and some driver core api updates to
mark things as const, which will also require some fixups due to new
stuff coming in through other trees in this merge window.
There are also a bunch of debugfs updates from Al, and there is at
least one user that does have a regression with these, but Al is
working on tracking down the fix for it. In my use (and everyone
else's linux-next use), it does not seem like a big issue at the
moment.
Here's a short list of the things in here:
- driver core rust bindings for PCI, platform, OF, and some i/o
functions.
We are almost at the "write a real driver in rust" stage now,
depending on what you want to do.
- misc device rust bindings and a sample driver to show how to use
them
- debugfs cleanups in the fs as well as the users of the fs api for
places where drivers got it wrong or were unnecessarily doing
things in complex ways.
- driver core const work, making more of the api take const * for
different parameters to make the rust bindings easier overall.
- other small fixes and updates
All of these have been in linux-next with all of the aforementioned
merge conflicts, and the one debugfs issue, which looks to be resolved
"soon""
* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
rust: device: Use as_char_ptr() to avoid explicit cast
rust: device: Replace CString with CStr in property_present()
devcoredump: Constify 'struct bin_attribute'
devcoredump: Define 'struct bin_attribute' through macro
rust: device: Add property_present()
saner replacement for debugfs_rename()
orangefs-debugfs: don't mess with ->d_name
octeontx2: don't mess with ->d_parent or ->d_parent->d_name
arm_scmi: don't mess with ->d_parent->d_name
slub: don't mess with ->d_name
sof-client-ipc-flood-test: don't mess with ->d_name
qat: don't mess with ->d_name
xhci: don't mess with ->d_iname
mtu3: don't mess wiht ->d_iname
greybus/camera - stop messing with ->d_iname
mediatek: stop messing with ->d_iname
netdevsim: don't embed file_operations into your structs
b43legacy: make use of debugfs_get_aux()
b43: stop embedding struct file_operations into their objects
carl9170: stop embedding file_operations into their objects
...
Conor Dooley found and fixed a problem in the pwm-microchip-core driver
that existed since the driver's birth in v6.5-rc1. It's about a corner
case that only happens if two pwm devices of the same chip are set to
the same long period.
The other problem is about the new pwm API that currently is only
supported by two hardware drivers. The fix prevents a NULL pointer
exception if one of the new functions is called for a pwm device with a
driver that only provides the old callbacks.
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Merge tag 'pwm/for-6.14-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux
Pull pwm fixes from Uwe Kleine-König:
"Two fixes.
Conor Dooley found and fixed a problem in the pwm-microchip-core
driver that existed since the driver's birth in v6.5-rc1. It's about a
corner case that only happens if two pwm devices of the same chip are
set to the same long period.
The other problem is about the new pwm API that currently is only
supported by two hardware drivers. The fix prevents a NULL pointer
exception if one of the new functions is called for a pwm device with
a driver that only provides the old callbacks"
* tag 'pwm/for-6.14-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux:
pwm: Ensure callbacks exist before calling them
pwm: microchip-core: fix incorrect comparison with max period
If one of the waveform functions is called for a chip that only supports
.apply(), we want that an error code is returned and not a NULL pointer
exception.
Fixes: 6c5126c640 ("pwm: Provide new consumer API functions for waveforms")
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/20250123172709.391349-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Constify the following API:
struct device *device_find_child(struct device *dev, void *data,
int (*match)(struct device *dev, void *data));
To :
struct device *device_find_child(struct device *dev, const void *data,
device_match_t match);
typedef int (*device_match_t)(struct device *dev, const void *data);
with the following reasons:
- Protect caller's match data @*data which is for comparison and lookup
and the API does not actually need to modify @*data.
- Make the API's parameters (@match)() and @data have the same type as
all of other device finding APIs (bus|class|driver)_find_device().
- All kinds of existing device match functions can be directly taken
as the API's argument, they were exported by driver core.
Constify the API and adapt for various existing usages.
BTW, various subsystem changes are squashed into this commit to meet
'git bisect' requirement, and this commit has the minimal and simplest
changes to complement squashing shortcoming, and that may bring extra
code improvement.
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Uwe Kleine-König <ukleinek@kernel.org> # for drivers/pwm
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20241224-const_dfc_done-v5-4-6623037414d4@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit cdd30ebb1b ("module: Convert symbol namespace to string
literal") only converted MODULE_IMPORT_NS() and EXPORT_SYMBOL_NS(),
leaving DEFAULT_SYMBOL_NAMESPACE as a macro expansion.
This commit converts DEFAULT_SYMBOL_NAMESPACE in the same way to avoid
annoyance for the default namespace as well.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some PWM hardwares (e.g. MC33XS2410) cannot implement a zero duty cycle
but can instead disable the hardware which also results in a constant
inactive output.
There are some checks (enabled with CONFIG_PWM_DEBUG) to help
implementing a driver without violating the normal rounding rules. Make
them less strict to let above described hardware pass without warning.
Reported-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Link: https://lore.kernel.org/r/20241103205215.GA509903@debian
Fixes: 3ad1f3a332 ("pwm: Implement some checks for lowlevel drivers")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Tested-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Link: https://lore.kernel.org/r/20241105153521.1001864-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Export the pwm_get_state_hw() function. This is useful in cases where
we want to know what the hardware is actually doing, rather than what
what we requested it should do.
Locking had to be rearranged to ensure that the chip is still
operational before trying to access ops now that this can be called
from outside the pwm core.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20241029-pwm-export-pwm_get_state_hw-v2-1-03ba063a3230@baylibre.com
[ukleinek: Add dummy for !CONFIG_PWM]
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Use the dedicated helper for comparing device names against strings.
Note, the current code has a check for the dev_name() against NULL.
With the current implementations of the device_add() and dev_set_name()
it most likely a theoretical assumption that that might happen, while
I don't see how. Hence, that check has simply been removed.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20241025142704.405340-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
This moves pwm_get() and friends above the functions handling
registration of pwmchips. The motivation is that character device
support needs pwm_get() and pwm_put() and so ideally is defined below
these and when a pwmchip is registered this registers the character
device. So the natural order is
pwm_get() and friend
pwm character device symbols
pwm_chip functions
. The advantage of having these in their natural order is that static
functions don't need to be forward declared.
Note that the diff that git produces for this change some functions are
moved down instead. This is technically equivalent, but not how this
change was created.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/193b3d933294da34e020650bff93b778de46b1c5.1726819463.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Provide API functions for consumers to work with waveforms.
Note that one relevant difference between pwm_get_state() and
pwm_get_waveform*() is that the latter yields the actually configured
hardware state, while the former yields the last state passed to
pwm_apply*() and so doesn't account for hardware specific rounding.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/6c97d27682853f603e18e9196043886dd671845d.1726819463.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Up to now the configuration of a PWM setting is described exclusively by
a struct pwm_state which contains information about period, duty_cycle,
polarity and if the PWM is enabled. (There is another member usage_power
which doesn't completely fit into pwm_state, I ignore it here for
simplicity.)
Instead of a polarity the new abstraction has a member duty_offset_ns
that defines when the rising edge happens after the period start. This
is more general, as with a pwm_state the rising edge can only happen at
the period's start or such that the falling edge is at the end of the
period (i.e. duty_offset_ns == 0 or duty_offset_ns == period_length_ns -
duty_length_ns).
A disabled PWM is modeled by .period_length_ns = 0. In my eyes this is a
nice usage of that otherwise unusable setting, as it doesn't define
anything about the future which matches the fact that consumers should
consider the state of the output as undefined and it's just there to say
"No further requirements about the output, you can save some power.".
Further I renamed period and duty_cycle to period_length_ns and
duty_length_ns. In the past there was confusion from time to time about
duty_cycle being measured in nanoseconds because people expected a
percentage of period instead. With "length_ns" as suffix the semantic
should be more obvious to people unfamiliar with the pwm subsystem.
period is renamed to period_length_ns for consistency.
The API for consumers doesn't change yet, but lowlevel drivers can
implement callbacks that work with pwm_waveforms instead of pwm_states.
A new thing about these callbacks is that the calculation of hardware
settings needed to implement a certain waveform is separated from
actually writing these settings. The motivation for that is that this
allows a consumer to query the hardware capabilities without actually
modifying the hardware state.
The rounding rules that are expected to be implemented in the
round_waveform_tohw() are: First pick the biggest possible period not
bigger than wf->period_length_ns. For that period pick the biggest
possible duty setting not bigger than wf->duty_length_ns. Third pick the
biggest possible offset not bigger than wf->duty_offset_ns. If the
requested period is too small for the hardware, it's expected that a
setting with the minimal period and duty_length_ns = duty_offset_ns = 0
is returned and this fact is signaled by a return value of 1.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/df0faa33bf9e7c9e2e5eab8d31bbf61e861bd401.1726819463.git.u.kleine-koenig@baylibre.com
[ukleinek: Update pwm_check_rounding() to return bool instead of int.]
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
This ensures that a pwm_chip that has no corresponding driver isn't used
and that a driver doesn't go away while a callback is still running.
In the presence of device links this isn't necessary yet (so this is no
fix) but for pwm character device support this is needed.
To not serialize all pwm_apply_state() calls, this introduces a per chip
lock. An additional complication is that for atomic chips a mutex cannot
be used (as pwm_apply_atomic() must not sleep) and a spinlock cannot be
held while calling an operation for a sleeping chip. So depending on the
chip being atomic or not a spinlock or a mutex is used.
An additional change implemented here is that on driver remove the
.free() callback is called for each requested pwm_device. This is the
right time because later (e.g. when the consumer calls pwm_put()) the
free function is (maybe) not available any more.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/026aa891c8270a11723a1ba7e4256f456f7e1e86.1726819463.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
There is only a single caller of this function, and that's in
drivers/pwm/core.c itself. So don't export the function.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20240712171821.1470833-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
While driving a PWM via the sysfs API it's hard to determine the right
order of writes to the pseudo files "period" and "duty_cycle":
If you want to go from duty_cycle/period = 50/100 to 150/300 you have to
write period first (because 150/100 is invalid). If however you start at
400/500 the duty_cycle must be configured first. The rule that works is:
If you increase period write period first, otherwise write duty_cycle
first. A complication however is that it's usually sensible to configure
the polarity before both period and duty_cycle. This can only be done if
the current state's duty_cycle and period configuration isn't bogus
though. It is still worse (but I think only theoretic) if you have a PWM
that only supports inverted polarity and you start with period = 0 and
polarity = normal. Then you can change neither period (because polarity
= normal is refused) nor polarity (because there is still period = 0).
To simplify the corner cases for userspace, let invalid target states
pass if the current state is invalid already.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20240628103519.105020-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
With the compiler caring for unlocking the mutex several functions can
be simplified. Benefit from that.
There is just one caller left for mutex_lock(&export->lock). The code
flow is too complicated there to convert it to the compiler assisted
variant.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/210010f2e579a92476462726e18e0135f6854909.1719520143.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
While the debugfs operations don't technically depend on an initialized
class, they loop over the idr that only can get entries when the class
is properly initialized.
This also fixes the ugly (but harmless) corner case that the debugfs
file stays around after the pwm class failed to initialize.
While at it, add an appropriate error message when class initialization
fails.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20240626222529.2901200-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
The last user of this function outside of core.c is gone, so it can be
made static.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20240607084416.897777-8-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Define all pwm core's symbols in the namespace "PWM". The necessary
module import statement is just added to the main header, this way every
file that knows about the public functions automatically has this
namespace available.
Thanks to Biju Das for pointing out a cut'n'paste failure in my initial
patch.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20240607160012.1206874-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
After assigning chip = pwm->chip; the compiler is free to assume that
pwm is non-NULL and so can optimize out the check for pwm against NULL.
While it's probably a programming error to pass a NULL pointer to
pwm_put() this shouldn't be dropped without careful consideration and
wasn't intended.
So assign chip only after the NULL check.
Reported-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/66a6f562-1fdd-4e45-995a-e7995432aa0c@baylibre.com
Fixes: 4c56b1434b ("pwm: Add a struct device to struct pwm_chip")
Link: https://lore.kernel.org/r/20240329101648.544155-2-u.kleine-koenig@pengutronix.de
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
It's required to not free the memory underlying a requested PWM
while a consumer still has a reference to it. While currently a pwm_chip
doesn't live long enough in all cases, linking the struct pwm to the
pwm_chip results in the right lifetime as soon as the pwmchip is living
long enough. This happens with the following commits.
Note this is a breaking change for all pwm drivers that don't use
pwmchip_alloc().
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> # for struct_size() and __counted_by()
Link: https://lore.kernel.org/r/7e9e958841f049026c0023b309cc9deecf0ab61d.1710670958.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
With the upcoming restructuring having all in a single file simplifies
things a bit. The relevant and somewhat visible changes are:
- Some dropped prototypes from include/linux/pwm.h that were only
necessary that core.c has a declaration of the symbols defined in
sysfs.c. The respective functions are static now.
- The pwm class now also exists if CONFIG_SYSFS isn't enabled. Having
CONFIG_SYSFS is not very relevant today, but even without it the
class and device stuff still provides lifetime tracking.
- Both files had an initcall, these are merged into a single one now.
Instead of a big #ifdef block for CONFIG_DEBUG_FS, a single
if (IS_ENABLED(CONFIG_DEBUG_FS)) is used now. This increases compile
coverage a bit and is a tad nicer on the eyes.
Link: https://lore.kernel.org/r/9e2d39a5280d7dda5bfc6682a8aef510148635b2.1710670958.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Memory holding a struct device must not be freed before the reference
count drops to zero. So a struct pwm_chip must not live in memory
freed by a driver on unbind. All in-tree drivers were fixed accordingly,
but as out-of-tree drivers, that were not adapted, still compile fine,
catch these in pwmchip_add().
Link: https://lore.kernel.org/r/35f5b229c98f78b2f6ce2397259a4a936be477c0.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
This function allocates a struct pwm_chip and driver data. Compared to
the status quo the split into pwm_chip and driver data is new, otherwise
it doesn't change anything relevant (yet).
The intention is that after all drivers are switched to use this
allocation function, its possible to add a struct device to struct
pwm_chip to properly track the latter's lifetime without touching all
drivers again. Proper lifetime tracking is a necessary precondition to
introduce character device support for PWMs (that implements atomic
setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
userspace support).
The new function pwmchip_priv() (obviously?) only works for chips
allocated with pwmchip_alloc().
Link: https://lore.kernel.org/r/9577d6053a5a52536057dc8654ff567181c2da82.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Currently a pwm_chip stores in its struct device *dev member a pointer
to the parent device. Preparing a change that embeds a full struct
device in struct pwm_chip, this accessor function should be used in all
drivers directly accessing chip->dev now. This way struct pwm_chip and
this new function can be changed without having to touch all drivers in
the same change set.
Make use of this function in the framework's core sources.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/cc30090d2f9762bed9854a55612144bccc910781.1707900770.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
This moves the functions called by pwm consumers above the functions
called by pwm providers. When character device support is added later
this is hooked into the chip registration functions. As the needed
callbacks are a kind of consumer and make use of the consumer functions,
having this order is more natural and prevents having to add
declarations for static functions.
Also move the global variables for pwm tables to the respective
functions to have them properly grouped.
Link: https://lore.kernel.org/r/eed83de07bdfb69b5ceba0b9aed757ee612dea8f.1706182805.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Apart from the two of_xlate implementations this member is write-only.
In the of_xlate functions of_pwm_xlate_with_flags() and
of_pwm_single_xlate() it's more sensible to check for args->args_count
because this is what is actually used in the device tree.
Acked-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/53d8c545aa8f79a920358be9e72e382b3981bdc4.1704835845.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
pwm->chip and pwm->chip->ops are used several times in this function.
Introduce local variables for these.
There is no semantical change, but with ARCH=arm, allmodconfig and
gcc-13 bloat-o-meter reports a slight improvement:
add/remove: 1/1 grow/shrink: 1/1 up/down: 8/-36 (-28)
Function old new delta
pwm_apply_state 476 480 +4
__initcall__kmod_core__307_1092_pwm_debugfs_init4 - 4 +4
__initcall__kmod_core__307_1090_pwm_debugfs_init4 4 - -4
pwm_request_from_chip 628 596 -32
Total: Before=15091, After=15063, chg -0.19%
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Some PWM devices require sleeping, for example if the pwm device is
connected over I2C. However, many PWM devices could be used from atomic
context, e.g. memory mapped PWM. This is useful for, for example, the
pwm-ir-tx driver which requires precise timing. Sleeping causes havoc
with the generated IR signal.
Since not all PWM devices can support atomic context, we also add a
pwm_might_sleep() function to check if is not supported.
Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
