08 Aug, 2019
1 commit
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Commit 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI")
made pwm_get unconditionally return the acpi_pwm_get return value if
the device passed to pwm_get has an ACPI fwnode.But even if the passed in device has an ACPI fwnode, it does not
necessarily have the necessary ACPI package defining its pwm bindings,
especially since the binding / API of this ACPI package has only been
introduced very recently.Up until now X86/ACPI devices which use a separate pwm controller for
controlling their LCD screen's backlight brightness have been relying
on the static lookup-list to get their pwm.pwm_get unconditionally returning the acpi_pwm_get return value breaks
this, breaking backlight control on these devices.This commit fixes this by making pwm_get fall back to the static
lookup-list if acpi_pwm_get returns -ENOENT.BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=96571
Reported-by: youling257@gmail.com
Fixes: 4a6ef8e37c4d ("pwm: Add support referencing PWMs from ACPI")
Cc: Nikolaus Voss
Signed-off-by: Hans de Goede
Reviewed-by: Andy Shevchenko
Acked-by: Nikolaus Voss
Signed-off-by: Thierry Reding
09 Jul, 2019
1 commit
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…erry.reding/linux-pwm
Pull pwm updates from Thierry Reding:
"This set of changes contains a new driver for SiFive SoCs as well as
enhancements to the core (device links are used to track dependencies
between PWM providers and consumers, support for PWM controllers via
ACPI, sysfs will now suspend/resume PWMs that it has claimed) and
various existing drivers"* tag 'pwm/for-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (37 commits)
pwm: fsl-ftm: Make sure to unlock mutex on failure
pwm: fsl-ftm: Use write protection for prescaler & polarity
pwm: fsl-ftm: More relaxed permissions for updating period
pwm: atmel-hlcdc: Add compatible for SAM9X60 HLCDC's PWM
pwm: bcm2835: Improve precision of PWM
leds: pwm: Support ACPI via firmware-node framework
pwm: Add support referencing PWMs from ACPI
pwm: rcar: Remove suspend/resume support
pwm: sysfs: Add suspend/resume support
pwm: Add power management descriptions
pwm: meson: Add documentation to the driver
pwm: meson: Add support PWM_POLARITY_INVERSED when disabling
pwm: meson: Don't cache struct pwm_state internally
pwm: meson: Read the full hardware state in meson_pwm_get_state()
pwm: meson: Simplify the calculation of the pre-divider and count
pwm: meson: Move pwm_set_chip_data() to meson_pwm_request()
pwm: meson: Add the per-channel register offsets and bits in a struct
pwm: meson: Add the meson_pwm_channel data to struct meson_pwm
pwm: meson: Pass struct pwm_device to meson_pwm_calc()
pwm: meson: Don't duplicate the polarity internally
...
26 Jun, 2019
23 commits
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Upon failure to enable clocks while trying to enable the PWM, make sure
to unlock the mutex that was taken to avoid a deadlock during subsequent
operations.Reported-by: kbuild test robot
Reported-by: Julia Lawall
Cc: Patrick Havelange
Signed-off-by: Thierry Reding -
Modifying the prescaler or polarity value must be done with the
write protection disabled. Currently this is working by chance as
the write protection is in a disabled state by default.
This patch makes sure that we enable/disable the write protection
when needed.Signed-off-by: Patrick Havelange
Signed-off-by: Thierry Reding -
The Flextimer has only one period for several channels. The PWM
subsystem doesn't allow to model something like that. The current
implementation simply disallows changing the period once it has
been set, having as a side effect that you need to enable and
disable the PWM if you want to change the period.The driver should allow as much freedom as possible for configuring
the period and duty cycle. Therefore, this patch reworks the code
to allow the following:- period and duty_cycle can be set at will when the PWM is disabled;
- when enabling a PWM, verify that the period is either not set yet,
or the same as the other already enabled PWM(s), and fail if not;
- allow to change the period on the fly when the PWM is the only one
enabled.It also allows to have different periods configured for different PWMs.
Only one period can be used at a time, thus the first PWM to be enabled
will set that period, only other PWMs with that same period can be
enabled at the same time. To use another PWM with another period, the
enabled PWMs must be disabled first.Example scenario :
echo 5000000 > pwm0/period #OK
echo 1000000 > pwm0/duty_cycle #OK
echo 1000000 > pwm1/period #OK
echo 1000000 > pwm1/duty_cycle #OK
echo 1 > pwm0/enable #OK
echo 1 > pwm1/enable #FAIL (pwm0/period != pwm1/period)
echo 0 > pwm0/enable #OK
echo 1 > pwm1/enable #OK
echo 1000000 > pwm0/period #OK
echo 2000000 > pwm0/period #OK
echo 1 > pwm0/enable #FAIL (pwm0/period != pwm1/period)
echo 2000000 > pwm1/period #OK (pwm1 still running, changed on the fly)
echo 1 > pwm0/enable #OK (now pwm0/period == pwm1/period)
echo 3000000 > pwm1/period #FAIL (other PWMs running)
echo 0 > pwm0/enable #OK
echo 3000000 > pwm1/period #OK (only this PWM running)Adapting the code to satisfy these constraints turned up a number of
additional issues with the current implementation:
- the prescaler value 0 was not used (when it could have been);
- when setting the period was not possible, the internal state was
inconsistent;
- the maximal value for configuring the period was never used;Since all of these interact with each other, rather than trying to fix
each individual issue, this patch reworks how the period and duty cycle
are set entirely, with the following additional improvements:
- implement the new apply() method instead of the individual methods;
- return the exact used period/duty_cycle values;
- more coherent argument types for period, duty_cycle;Signed-off-by: Patrick Havelange
Signed-off-by: Thierry Reding -
Add compatible string for SAM9X60 HLCDC's PWM.
Signed-off-by: Claudiu Beznea
Signed-off-by: Thierry Reding -
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
Signed-off-by: Sean Young
Acked-by: Stefan Wahren
Signed-off-by: Thierry Reding -
In analogy to referencing a GPIO using the "gpios" property from ACPI,
support referencing a PWM using the "pwms" property.ACPI entries must look like
Package () {"pwms", Package ()
{ , , [, ]}}In contrast to the DT implementation, only _one_ PWM entry in the "pwms"
property is supported. As a consequence "pwm-names"-property and
con_id lookup aren't supported.Support for ACPI is added via the firmware-node framework which is an
abstraction layer on top of ACPI/DT. To keep this patch clean, DT and
ACPI paths are kept separate. The firmware-node framework could be used
to unify both paths in a future patch.To support leds-pwm driver, an additional method devm_fwnode_pwm_get()
which supports both ACPI and DT configuration is exported.Signed-off-by: Nikolaus Voss
[thierry.reding@gmail.com: fix build failures for !ACPI]
Signed-off-by: Thierry Reding -
According to the Documentation/pwm.txt, all PWM consumers should
implement power management instead of the PWM driver. So, this
patch removes suspend/resume support.Signed-off-by: Yoshihiro Shimoda
Reviewed-by: Geert Uytterhoeven
Reviewed-by: Simon Horman
Signed-off-by: Thierry Reding -
According to the Documentation/pwm.txt, all PWM consumers should have
power management. Since this sysfs interface is one of consumers so that
this patch adds suspend/resume support.Signed-off-by: Yoshihiro Shimoda
Reviewed-by: Geert Uytterhoeven
Reviewed-by: Simon Horman
[thierry.reding@gmail.com: fix build warnings for !PM]
Signed-off-by: Thierry Reding -
Add links to the datasheet and a short summary how the hardware works.
The goal is to make it easier for other developers to understand why the
pwm-meson driver is implemented the way it is.Suggested-by: Uwe Kleine-König
Co-authored-by: Neil Armstrong
Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
meson_pwm_apply() has to consider the PWM polarity when disabling the
output.
With enabled=false and polarity=PWM_POLARITY_NORMAL the output needs to
be LOW. The driver already supports this.
With enabled=false and polarity=PWM_POLARITY_INVERSED the output needs
to be HIGH. Implement this in the driver by internally enabling the
output with the same settings that we already use for "period == duty".This fixes a PWM API violation which expects that the driver honors the
polarity also for enabled=false. Due to the IP block not supporting this
natively we only get "an as close as possible" to 100% HIGH signal (in
my test setup with input clock of 24MHz and measuring the output with a
logic analyzer at 24MHz sampling rate I got a duty cycle of 99.998475%
on a Khadas VIM).Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
The PWM core already caches the "current struct pwm_state" as the
"current state of the hardware registers" inside struct pwm_device.Drop the struct pwm_state from struct meson_pwm_channel in favour of the
struct pwm_state in struct pwm_device. While here also drop any checks
based on the pwm_state because the PWM core already takes care of this.No functional changes intended.
Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
Update the meson_pwm_get_state() implementation to take care of all
information in the registers instead of only reading the "enabled"
state.The PWM output is only enabled if two conditions are met:
1. the per-channel clock is enabled
2. the PWM output is enabledCalculate the PWM period and duty cycle using the reverse formula which
we already have in meson_pwm_calc() and update struct pwm_state with the
results.As result of this /sys/kernel/debug/pwm now shows the PWM state set by
the bootloader (or firmware) after booting Linux.Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
Replace the loop to calculate the pre-divider and count with two
separate div64_u64() calculations. This makes the code easier to read
and improves the precision.Three example cases:
1) 32.768kHz LPO clock for the SDIO wifi chip on Khadas VIM
clock input: 500MHz (FCLK_DIV4)
period: 30518ns
duty cycle: 15259ns
old algorithm: pre_div=0, cnt=15259
new algorithm: pre_div=0, cnt=15259
(no difference in calculated values)2) PWM LED on Khadas VIM
clock input: 24MHz (XTAL)
period: 7812500ns
duty cycle: 7812500ns
old algorithm: pre_div=2, cnt=62004
new algorithm: pre_div=2, cnt=62500
Using a scope (24MHz sampling rate) shows the actual difference:
- old: 7753000ns, off by -59500ns (0.7616%)
- new: 7815000ns, off by +2500ns (0.032%)3) Theoretical case where pre_div is different
clock input: 24MHz (XTAL)
period: 2730624ns
duty cycle: 1365312ns
old algorithm: pre_div=1, cnt=32768
new algorithm: pre_div=0, cnt=65534
Using a scope (24MHz sampling rate) shows the actual difference:
- old: 2731000ns
- new: 2731000ns
(my scope is not precise enough to measure the difference if there's
any)Suggested-by: Uwe Kleine-König
Acked-by: Uwe Kleine-König
Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
All existing PWM drivers (except pwm-meson and two other ones) call
pwm_set_chip_data() from their pwm_ops.request() callback. Now that we
can access the struct meson_pwm_channel from struct meson_pwm we can do
the same.Move the call to pwm_set_chip_data() to meson_pwm_request() and drop the
custom meson_pwm_add_channels(). This makes the implementation
consistent with other drivers and makes it slightly more obvious
thatpwm_get_chip_data() cannot be used from pwm_ops.get_state() (because
that's called by the PWM core before pwm_ops.request()).No functional changes intended.
Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
Introduce struct meson_pwm_channel_data which contains the per-channel
offsets for the PWM register and REG_MISC_AB bits. Replace the existing
switch (pwm->hwpwm) statements with an access to the new struct.This simplifies the code and will make it easier to implement
pwm_ops.get_state() because the switch-case which all per-channel
registers and offsets (as previously implemented in meson_pwm_enable())
doesn't have to be duplicated.No functional changes intended.
Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
Make struct meson_pwm_channel accessible from struct meson_pwm.
PWM core has a limitation: per-channel data can only be set after
pwmchip_add() is called. However, pwmchip_add() internally calls
pwm_ops.get_state(). If pwm_ops.get_state() needs access to the
per-channel data it has to obtain it from struct pwm_chip and struct
pwm_device's hwpwm information.Add a struct meson_pwm_channel for each PWM channel to struct meson_pwm
so the pwm_ops.get_state() callback can be implemented as it needs
access to the clock from struct meson_pwm_channel.Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
meson_pwm_calc() is the last function that accepts a struct
meson_pwm_channel. meson_pwm_enable(), meson_pwm_disable() and
meson_pwm_apply() for example are all taking a struct pwm_device as
parameter. When they need the struct meson_pwm_channel these functions
simply call pwm_get_chip_data() internally.Make meson_pwm_calc() consistent with the other functions in the
meson-pwm driver by passing struct pwm_device to it as well. The value
of the "id" parameter is actually pwm->hwpwm, but the driver never read
the "id" parameter, which is why there's no replacement for it in the
new code.No functional changes.
Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
Let meson_pwm_calc() use the polarity from struct pwm_state directly.
This removes a level of indirection where meson_pwm_apply() first had to
set a driver-internal inverter mask which was then only used by
meson_pwm_calc().Instead of adding the polarity as parameter to meson_pwm_calc() switch
to struct pwm_state directly to make it easier to see where the
parameters are actually coming from.Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
MISC_CLK_SEL_WIDTH is only used in one place where it's converted into
a bit-mask. Rename and change the macro to be a bit-mask so that
conversion is not needed anymore. No functional changes intended.Reviewed-by: Neil Armstrong
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
meson_pwm_calc() ensures that "lo" is always less than 16 bits wide
(otherwise it would overflow into the "hi" part of the REG_PWM_{A,B}
register).
Use GENMASK and FIELD_PREP for the lo and hi values to make it easier to
spot how wide these are internally. Additionally this is a preparation
step for the .get_state() implementation where the GENMASK() for lo and
hi becomes handy because it can be used with FIELD_GET() to extract the
values from the register REG_PWM_{A,B} register.No functional changes intended.
Reviewed-by: Neil Armstrong
Reviewed-by: Uwe Kleine-König
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
Simplify the code which fetches the input clock for a PWM channel by
using devm_clk_get_optional().
This comes with a small functional change: previously all errors except
EPROBE_DEFER were ignored. Now all other errors are also treated as
errors. If no input clock is present devm_clk_get_optional() will return
NULL instead of an error which matches the behavior of the old code.Reviewed-by: Neil Armstrong
Reviewed-by: Uwe Kleine-König
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
This is a preparation for a future cleanup. Pass struct pwm_device
instead of passing the individual values required by each function as
these can be obtained for each struct pwm_device instance.As a nice side-effect the driver now uses "switch (pwm->hwpwm)"
everywhere. Before some functions used "switch (id)" while others used
"switch (pwm->hwpwm)".No functional changes.
Reviewed-by: Neil Armstrong
Reviewed-by: Uwe Kleine-König
Signed-off-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
When the PWM mode of TCU2 channels is disabled, their corresponding pin
does not always return to its initial level. Force this by using a small
trick: we set duty > period, which is an invalid configuration for the
hardware, which then correctly resets the pin to the initial level.Signed-off-by: Paul Cercueil
Signed-off-by: Thierry Reding
25 Jun, 2019
8 commits
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This is cleaner, more future-proof, and incidentally it also fixes the
PWM resetting its config when stopped/started several times.Signed-off-by: Paul Cercueil
Signed-off-by: Thierry Reding -
Right now none of the Ingenic-based boards probe this driver from
devicetree. This driver defined three compatible strings for the exact
same behaviour. Before these strings are used, we can remove two of
them.Signed-off-by: Paul Cercueil
Signed-off-by: Thierry Reding -
The Amlogic G12A and G12B Documentation is wrong, the AO xtal and clk81
clock source order is reversed, and validated when adding DVFS support
by using the PWM AO D output to control the CPU supply voltage.The vendor tree also uses the reversed xtal and clk81 order at [1].
[1] https://github.com/hardkernel/linux/blob/odroidn2-4.9.y/drivers/amlogic/pwm/pwm_meson.c#L462
Fixes: f41efceb46e6 ("pwm: meson: Add clock source configuration for Meson G12A")
Signed-off-by: Neil Armstrong
Acked-by: Kevin Hilman
Signed-off-by: Thierry Reding -
Signed-off-by: Neil Armstrong
Reviewed-by: Martin Blumenstingl
Signed-off-by: Thierry Reding -
STM32 Timers support generic 3 cells PWM to encode PWM number, period
and polarity.Fixes: 7edf7369205b ("pwm: Add driver for STM32 plaftorm")
Signed-off-by: Fabrice Gasnier
Reviewed-by: Benjamin Gaignard
Signed-off-by: Thierry Reding -
Add a device link between the PWM consumer and the PWM provider. This
enforces the PWM user to get suspended before the PWM provider. It
allows proper synchronization of suspend/resume sequences: the PWM user
is responsible for properly stopping PWM, before the provider gets
suspended: see [1]. Add the device link in:
- of_pwm_get()
- pwm_get()
- devm_*pwm_get() variants
as it requires a reference to the device for the PWM consumer.[1] https://lkml.org/lkml/2019/2/5/770
Suggested-by: Thierry Reding
Acked-by: Uwe Kleine-König
Signed-off-by: Fabrice Gasnier
Signed-off-by: Thierry Reding -
Add suspend/resume PM sleep ops. When going to low power, enforce the PWM
channel isn't active. Let the PWM consumers disable it during their own
suspend sequence. Only perform a check here, and handle the pinctrl states.
See [1].
[1] https://lkml.org/lkml/2019/2/5/770Signed-off-by: Fabrice Gasnier
Signed-off-by: Thierry Reding -
Adds a PWM driver for PWM chip present in SiFive's HiFive Unleashed SoC.
Signed-off-by: Wesley W. Terpstra
[Atish: Various fixes and code cleanup]
Signed-off-by: Atish Patra
Signed-off-by: Yash Shah
Reviewed-by: Uwe Kleine-König
Signed-off-by: Thierry Reding
19 Jun, 2019
2 commits
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