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 <u.kleine-koenig@pengutronix.de>
Co-authored-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 enabled
Calculate 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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <u.kleine-koenig@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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 <narmstrong@baylibre.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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: f41efceb46 ("pwm: meson: Add clock source configuration for Meson G12A")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Nothing out of the ordinary this cycle. The bulk of this is a collection
of fixes for existing drivers and some cleanups. There's one new driver
for i.MX SoCs and addition of support for some new variants to existing
drivers.
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Merge tag 'pwm/for-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm
Pull pwm updates from Thierry Reding:
"Nothing out of the ordinary this cycle.
The bulk of this is a collection of fixes for existing drivers and
some cleanups. There's one new driver for i.MX SoCs and addition of
support for some new variants to existing drivers"
* tag 'pwm/for-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
pwm: meson: Add clock source configuration for Meson G12A
dt-bindings: pwm: Update bindings for the Meson G12A Family
pwm: samsung: Don't uses devm_*() functions in ->request()
pwm: Clear chip_data in pwm_put()
pwm: Add i.MX TPM PWM driver support
dt-bindings: pwm: Add i.MX TPM PWM binding
pwm: imx27: Use devm_platform_ioremap_resource() to simplify code
pwm: meson: Use the spin-lock only to protect register modifications
pwm: meson: Don't disable PWM when setting duty repeatedly
pwm: meson: Consider 128 a valid pre-divider
pwm: sysfs: fix typo "its" -> "it's"
pwm: tiehrpwm: Enable compilation for ARCH_K3
dt-bindings: pwm: tiehrpwm: Add TI AM654 SoC specific compatible
pwm: tiehrpwm: Update shadow register for disabling PWMs
pwm: img: Turn final 'else if' into 'else' in img_pwm_config
pwm: Fix deadlock warning when removing PWM device
For the PWM controller in the Meson G12A SoC, the EE domain and AO domain
have different clock sources. This patch tries to describe them in the
DT compatible data. The two AO PWM controller has different clock source,
but the first AO controller (A & B) can reuse the AXG parents name.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Holding the spin-lock for all of the code in meson_pwm_apply() can
result in a "BUG: scheduling while atomic". This can happen because
clk_get_rate() (which is called from meson_pwm_calc()) may sleep.
Only hold the spin-lock when modifying registers to solve this.
The reason why we need a spin-lock in the driver is because the
REG_MISC_AB register is shared between the two channels provided by one
PWM controller. The only functions where REG_MISC_AB is modified are
meson_pwm_enable() and meson_pwm_disable() so the register reads/writes
in there need to be protected by the spin-lock.
The original code also used the spin-lock to protect the values in
struct meson_pwm_channel. This could be necessary if two consumers can
use the same PWM channel. However, PWM core doesn't allow this so we
don't need to protect the values in struct meson_pwm_channel with a
lock.
Fixes: 211ed63075 ("pwm: Add support for Meson PWM Controller")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
There is an abnormally low about 20ms,when setting duty repeatedly.
Because setting the duty will disable PWM and then enable. Delete
this operation now.
Fixes: 211ed63075 ("pwm: Add support for Meson PWM Controller")
Signed-off-by: Bichao Zheng <bichao.zheng@amlogic.com>
[ Dropped code instead of hiding it behind a comment ]
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The pre-divider allows configuring longer PWM periods compared to using
the input clock directly. The pre-divider is 7 bit wide, meaning it's
maximum value is 128 (the register value is off-by-one: 0x7f or 127).
Change the loop to also allow for the maximum possible value to be
considered valid.
Fixes: 211ed63075 ("pwm: Add support for Meson PWM Controller")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This flag was historically used to indicate that a clk is a "basic" type
of clk like a mux, divider, gate, etc. This never turned out to be very
useful though because it was hard to cleanly split "basic" clks from
other clks in a system. This one flag was a way for type introspection
and it just didn't scale. If anything, it was used by the TI clk driver
to indicate that a clk_hw wasn't contained in the SoC specific clk
structure. We can get rid of this define now that TI is finding those
clks a different way.
Cc: Tero Kristo <t-kristo@ti.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: <linux-mips@vger.kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: <linux-pwm@vger.kernel.org>
Cc: <linux-amlogic@lists.infradead.org>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Current clock name looks like this:
/soc/bus@ffd00000/pwm@1b000#mux0
This is bad because CCF uses the clock to create a directory in clk debugfs.
With such name, the directory creation (silently) fails and the debugfs
entry end up being created at the debugfs root.
With this change, the clock name will now be:
ffd1b000.pwm#mux0
This matches the clock naming scheme used in the ethernet and mmc driver.
It also fixes the problem with debugfs.
Fixes: 36af66a790 ("pwm: Convert to using %pOF instead of full_name")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Using the pwm-meson driver on the 32-bit SoCs causes memory corruption.
The result are some hard-to-explain errors, for example
devm_clk_register() crashes with a NULL dereference somewhere deep in
the common clock framework code. In some cases the kernel even refused
to boot when any of the PWM controllers were enabled on Meson8b.
The root cause is an incorrect memory size in the devm_kcalloc() call in
meson_pwm_probe(). The code allocates an array of meson_pwm_channel
structs, but the size given is the size of the meson_pwm struct (which
seems like a small copy-and-paste error, as meson_pwm is allocated a few
lines above).
Even with this typo the code seemed to work fine on the 64-bit GX SoCs
(maybe due to the structs having the same size in the compiled result,
but I haven't checked this further).
Fixes: 211ed63075 ("pwm: Add support for Meson PWM Controller")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
For PWM controller in the Meson-AXG SoC, the EE domain and AO domain
have different clock sources. This patch tries to describe them in the
DT compatible data.
Signed-off-by: Jian Hu <jian.hu@amlogic.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Now that we have a custom printf format specifier, convert users of
full_name to use %pOF instead. This is preparation to remove storing
of the full path string for each node.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Carlo Caione <carlo@caione.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: linux-pwm@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-amlogic@lists.infradead.org
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
When using input clocks with high rates, such as clk81 (166MHz), the
fin_ns = NSEC_PER_SEC / fin_freq can introduce a significant error.
Ex: fin_freq = 166666667, NSEC_PER_SEC = 1000000000
fin_ns = 5,9999999
which is, of course, rounded down to 5. This introduces an error of ~20%
on the period requested from the PWM.
This patch uses ps instead of ns (and 64 bit integers) to perform the
calculation. This should give a good enough precision.
Fixes: 211ed63075 ("pwm: Add support for Meson PWM Controller")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
squash! pwm: meson: Improve pwm calculation precision
On the gxbb (and gxl) family, the PWMs of the AO domain require a
specific compatible because the possible input clocks are different
from the EE PWMs input clocks.
Since the number of possible input clocks is also different, the
'num_parents' field is added to all the Meson PWM data.
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This is a very tiny pull request, with just a new driver for HiSilicon
BVT SoCs and a cleanup for the Amlogic Meson driver.
There are other patches on the list, but my timing was really bad this
time and I ended up not having the time to look at them in enough detail
to be comfortable merging them.
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Merge tag 'pwm/for-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm
Pull pwm updates from Thierry Reding:
"This is a very tiny pull request, with just a new driver for HiSilicon
BVT SoCs and a cleanup for the Amlogic Meson driver.
There are other patches on the list, but my timing was really bad this
time and I ended up not having the time to look at them in enough
detail to be comfortable merging them"
* tag 'pwm/for-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
pwm: Add PWM driver for HiSilicon BVT SOCs
pwm: meson: Remove unneeded platform MODULE_ALIAS
The Amlogic Meson is a DT-only platform, which means the devices are
registered via OF and not using the legacy platform devices support.
So there's no need to have a MODULE_ALIAS("platform:meson-pwm") since
the reported uevent MODALIAS to user-space will always be the OF one.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The driver uses the spin_lock but does not initialize it. Fix it.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
When building with -Wmaybe-uninitialized, we get a couple of harmless
warnings about three functions in this new driver that don't look
safe to the compiler:
drivers/pwm/pwm-meson.c: In function 'meson_pwm_get_state':
drivers/pwm/pwm-meson.c:355:26: error: 'mask' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/pwm/pwm-meson.c: In function 'meson_pwm_disable':
drivers/pwm/pwm-meson.c:263:13: error: 'enable' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/pwm/pwm-meson.c: In function 'meson_pwm_apply':
drivers/pwm/pwm-meson.c:231:13: error: 'clk_shift' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/pwm/pwm-meson.c:231:36: error: 'enable' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/pwm/pwm-meson.c:231:24: error: 'clk_enable' may be used uninitialized in this function [-Werror=maybe-uninitialized]
Specifically, if we have a device with an ID other than 0 or 1,
this would result in undefined behavior. This is currently not
possible, but the compiler cannot be expected to know this.
This patch adds a 'default' clause to let the compiler know
what to do instead, which shuts up the warning and makes the
code slightly more resiliant in case it gets extended to other
identifiers.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Add support for the PWM controller found in the Amlogic SoCs. This
driver supports the Meson8b and GXBB SoCs.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Martin Blumenstingl