Commit Graph

10 Commits

Author SHA1 Message Date
Linus Torvalds
4b4bb99b62 pwm: Changes for v4.18-rc1
This contains a couple of fixes and cleanups for the Meson and ACPI/LPSS
 drivers as well as capture support for STM32. Note that given the cross-
 subsystem changes, the STM32 patches were merged through the MFD and PWM
 trees, both sharing an immutable branch.
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Merge tag 'pwm/for-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm updates from Thierry Reding:
 "This contains a couple of fixes and cleanups for the Meson and
  ACPI/LPSS drivers as well as capture support for STM32.

  Note that given the cross- subsystem changes, the STM32 patches were
  merged through the MFD and PWM trees, both sharing an immutable
  branch"

* tag 'pwm/for-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
  pwm: stm32: Fix build warning with CONFIG_DMA_ENGINE disabled
  pwm: stm32: Enforce dependency on CONFIG_MFD_STM32_TIMERS
  ACPI / LPSS: Add missing prv_offset setting for byt/cht PWM devices
  pwm: lpss: platform: Save/restore the ctrl register over a suspend/resume
  dt-bindings: mfd: stm32-timers: Add support for dmas
  pwm: simplify getting .drvdata
  pwm: meson: Fix allocation of PWM channel array
2018-06-14 16:25:43 +09:00
Arnd Bergmann
414c52b789 pwm: stm32: Fix build warning with CONFIG_DMA_ENGINE disabled
Without dmaengine support, we get a harmless warning about an unused
function:

	drivers/pwm/pwm-stm32.c:166:12: error: 'stm32_pwm_capture' defined but not used [-Werror=unused-function]

Changing the #ifdef to an IS_ENABLED() check shuts up that warning and
is slightly nicer to read.

Fixes: 53e38fe73f ("pwm: stm32: Add capture support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2018-06-06 10:15:55 +02:00
Fabrice Gasnier
a3b51be3cd pwm: stm32: Initialize raw local variables
This removes build warning when COMPILE_TEST=y and MFD_STM32_TIMERS=n
in drivers/pwm/pwm-stm32.c. In function 'stm32_pwm_capture' 'raw_prd' and
'raw_dty' may be used uninitialized in this function
[-Wmaybe-uninitialized]

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-06-04 07:13:40 +01:00
Fabrice Gasnier
ab3a897847 pwm: stm32: Use input prescaler to improve period capture
Using input prescaler, capture unit will trigger DMA once every
configurable /2, /4 or /8 events (rising edge). This helps improve
period (only) capture accuracy at high rates.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-05-16 09:11:19 +01:00
Fabrice Gasnier
d66ffb91c3 pwm: stm32: Improve capture by tuning counter prescaler
Currently, capture is based on timeout window to configure prescaler.
PWM capture framework provides 1s window at the time of writing.

There's place for improvement, after input signal has been captured once:
- Finer tune counter clock prescaler, by using 1st capture result (with
arbitrary margin).
- Do a 2nd capture, with scaled capture window.
This increases accuracy, especially at high rates.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-05-16 09:11:13 +01:00
Fabrice Gasnier
53e38fe73f pwm: stm32: Add capture support
Add support for PMW input mode on pwm-stm32. STM32 timers support
period and duty cycle capture as long as they have at least two PWM
channels. One capture channel is used for period (rising-edge), one
for duty-cycle (falling-edge).
When there's only one channel available, only period can be captured.
Duty-cycle is simply zero'ed in such a case.

Capture requires exclusive access (e.g. no pwm output running at the
same time, to protect common prescaler).
Timer DMA burst mode (from MFD core) is being used, to take two
snapshots of capture registers (upon each period rising edge).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2018-05-16 09:10:53 +01:00
Fabrice Gasnier
4eb67a2096 pwm: stm32: Protect common prescaler for all channels
There may be a race, when configuring two PWM channels, with different
prescaler values, when there's no active channel yet.
Add mutex lock to avoid concurrent access on PWM apply state.
This is also precursor patch for PWM capture support.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2018-03-28 00:37:37 +02:00
Fabrice Gasnier
3af0bdd1d0 pwm: stm32: Remove unused struct device
dev is never assigned or used. Remove it.

Fixes: 7edf736920 ("pwm: Add driver for STM32 plaftorm")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2018-03-28 00:36:12 +02:00
Benjamin Gaignard
d7a131d3a4 pwm: stm32: Adopt SPDX identifier
Add SPDX identifier to make it easier to determine the license of the
file.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2018-03-27 23:22:31 +02:00
Benjamin Gaignard
7edf736920 pwm: Add driver for STM32 plaftorm
This driver adds support for PWM driver on STM32 platform.
The SoC have multiple instances of the hardware IP and each
of them could have small differences: number of channels,
complementary output, auto reload register size...

version 9:
- fix commit message header
- remove one space MODULE_ALIAS

version 8:
- fix comments done by Thierry on version 7

version 6:
- change st,breakinput parameter to make it usuable for stm32f7 too.

version 4:
- detect at probe time hardware capabilities
- fix comments done on v2 and v3
- use PWM atomic ops

version 2:
- only keep one comptatible
- use DT parameters to discover hardware block configuration

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2017-01-25 16:11:55 +00:00