[PATCH v2 00/16] extend PWM framework to support PWM modes
Claudiu Beznea
claudiu.beznea at microchip.com
Fri Jan 12 06:22:47 PST 2018
Hi all,
Please give feedback on these patches which extends the PWM framework in order
to support multiple PWM modes of operations. This series is a rework of [1].
The current patch series add the following PWM modes:
- PWM mode normal
- PWM mode complementary
- PWM mode push-pull
Normal mode - for PWM chips with one output per PWM channel; output
waveforms looks like this:
__ __ __ __
PWM __| |__| |__| |__| |__
<--T-->
Complementary mode - for PWM chips with more than one output per PWM
channel; output waveforms for a PWM controller with 2 outputs per PWM
channel may looks line this:
__ __ __ __
PWMH1 __| |__| |__| |__| |__
__ __ __ __ __
PWML1 |__| |__| |__| |__|
<--T-->
Where T is the signal period.
Push-pull mode - for PWM chips with mode than one output per PWM channel;
output waveform for a PWM controller with 2 outputs per PWM channel, in
push-pull mode, with normal polarity looks like this:
__ __
PWMH __| |________| |________
__ __
PWML ________| |________| |__
<--T-->
If polarity is inversed:
__ ________ ________
PWMH |__| |__|
________ ________ __
PWML |__| |__|
<--T-->
Where T is the signal period.
Every PWM device from a PWM chip could be configured in the modes registered
by PWM chip. For this, the PWM chip structure contains a field called caps which
keeps the PWM modes. At probe time the PWM chip registers the supported modes
and PWM devices could switch to the modes registered by PWM chips. For the moment,
in my opinion, it is not neccessary to add a new hook in pwm_ops to go through
the driver to check the capabilities of a single PWM device (as was proposed
in [1]).
I choosed to consider that a PWM controller with 2 outputs to also be capable to
work in normal mode, since the outputs could be connected independently to other
devices.
If the drivers doesn't register any PWM capabilities the default capabilities
will be used (currently, these includes PWM mode normal).
These PWM mode could be configured via sysfs, or pwm_set_mode() +
pwm_apply_state() (for driver clients), or via DT.
In sysfs, user could check the PWM controller capabilities by reading modes file
of PWM chip:
root at sama5d2-xplained:/sys/class/pwm/pwmchip0# ls -l
total 0
lrwxrwxrwx 1 root root 0 Oct 7 03:18 device -> ../../../f802c000.pwm
--w------- 1 root root 4096 Oct 7 03:18 export
-r--r--r-- 1 root root 4096 Oct 7 03:18 modes
-r--r--r-- 1 root root 4096 Oct 7 03:18 npwm
drwxr-xr-x 2 root root 0 Oct 7 03:18 power
lrwxrwxrwx 1 root root 0 Oct 7 03:18 subsystem -> ../../../../../../../class/pwm
-rw-r--r-- 1 root root 4096 Oct 7 01:20 uevent
--w------- 1 root root 4096 Oct 7 03:18 unexport
root at sama5d2-xplained:/sys/class/pwm/pwmchip0# cat modes
normal complementary push-pull
And the current capability of the PWM device could be checked as follows:
root at sama5d2-xplained:/sys/class/pwm/pwmchip0/pwm1# ls -l
-r--r--r-- 1 root root 4096 Feb 9 10:54 capture
-rw-r--r-- 1 root root 4096 Feb 9 10:54 duty_cycle
-rw-r--r-- 1 root root 4096 Feb 9 10:54 enable
-rw-r--r-- 1 root root 4096 Feb 9 10:54 mode
-rw-r--r-- 1 root root 4096 Feb 9 10:54 period
-rw-r--r-- 1 root root 4096 Feb 9 10:55 polarity
drwxr-xr-x 2 root root 0 Feb 9 10:54 power
-rw-r--r-- 1 root root 4096 Feb 9 10:54 uevent
root at sama5d2-xplained:/sys/class/pwm/pwmchip0/pwm1# cat mode
normal
The PWM push-pull mode could be usefull in applications like
half bridge converters.
This series also add support for PWM modes on atmel SAMA5D2 SoC.
Thank you,
Claudiu Beznea
[1] https://www.spinics.net/lists/arm-kernel/msg580275.html
Changes in v2:
- remove of_xlate and of_pwm_n_cells and use generic functions to pharse DT
inputs; this is done in patches 1, 2, 3, 4, 5, 6, 7 of this series; this will
make easy the addition of PWM mode support from DT
- add PWM mode normal
- register PWM modes as capabilities of PWM chips at driver probe and, in case
driver doesn't provide these capabilities use default ones
- change the way PWM mode is pharsed via DT by using a new input for pwms
binding property
Claudiu Beznea (16):
drivers: pwm: core: use a single of xlate function
pwm: pxa: update documentation regarding pwm-cells
pwm: cros-ec: update documentation regarding pwm-cells
pwm: clps711x: update documentation regarding pwm-cells
ARM: dts: clps711x: update pwm-cells
ARM: dts: pxa: update pwm-cells
arm64: dts: rockchip: update pwm-cells
drivers: pwm: core: extend PWM framework with PWM modes
drivers: pwm: core: add PWM mode to pwm_config()
pwm: Add PWM modes
pwm: add documentation for PWM modes
pwm: atmel: add pwm capabilities
drivers: pwm: core: add push-pull mode support
pwm: add push-pull mode
pwm: add documentation for pwm push-pull mode
pwm: atmel: add push-pull mode support
.../bindings/pwm/cirrus,clps711x-pwm.txt | 4 +-
.../devicetree/bindings/pwm/google,cros-ec-pwm.txt | 4 +-
Documentation/devicetree/bindings/pwm/pwm.txt | 23 ++++-
Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 6 +-
Documentation/pwm.txt | 47 ++++++++-
arch/arm/boot/dts/ep7209.dtsi | 2 +-
arch/arm/boot/dts/pxa25x.dtsi | 4 +-
arch/arm/boot/dts/pxa27x.dtsi | 8 +-
arch/arm/boot/dts/pxa3xx.dtsi | 8 +-
arch/arm/mach-s3c24xx/mach-rx1950.c | 5 +-
arch/arm64/boot/dts/rockchip/rk3399-gru-kevin.dts | 2 +-
arch/arm64/boot/dts/rockchip/rk3399-gru.dtsi | 2 +-
drivers/bus/ts-nbus.c | 2 +-
drivers/clk/clk-pwm.c | 3 +-
drivers/gpu/drm/i915/intel_panel.c | 8 +-
drivers/hwmon/pwm-fan.c | 2 +-
drivers/input/misc/max77693-haptic.c | 2 +-
drivers/input/misc/max8997_haptic.c | 3 +-
drivers/leds/leds-pwm.c | 2 +-
drivers/media/rc/ir-rx51.c | 2 +-
drivers/media/rc/pwm-ir-tx.c | 2 +-
drivers/pwm/core.c | 112 ++++++++++++++-------
drivers/pwm/pwm-atmel-hlcdc.c | 2 -
drivers/pwm/pwm-atmel-tcb.c | 2 -
drivers/pwm/pwm-atmel.c | 100 ++++++++++++------
drivers/pwm/pwm-bcm-iproc.c | 2 -
drivers/pwm/pwm-bcm-kona.c | 2 -
drivers/pwm/pwm-bcm2835.c | 2 -
drivers/pwm/pwm-berlin.c | 2 -
drivers/pwm/pwm-clps711x.c | 11 --
drivers/pwm/pwm-cros-ec.c | 20 ----
drivers/pwm/pwm-fsl-ftm.c | 2 -
drivers/pwm/pwm-hibvt.c | 2 -
drivers/pwm/pwm-imx.c | 8 --
drivers/pwm/pwm-lpc18xx-sct.c | 2 -
drivers/pwm/pwm-meson.c | 2 -
drivers/pwm/pwm-omap-dmtimer.c | 2 -
drivers/pwm/pwm-pxa.c | 19 ----
drivers/pwm/pwm-renesas-tpu.c | 2 -
drivers/pwm/pwm-rockchip.c | 5 -
drivers/pwm/pwm-samsung.c | 3 -
drivers/pwm/pwm-sun4i.c | 2 -
drivers/pwm/pwm-tiecap.c | 2 -
drivers/pwm/pwm-tiehrpwm.c | 2 -
drivers/pwm/pwm-vt8500.c | 2 -
drivers/pwm/pwm-zx.c | 2 -
drivers/pwm/sysfs.c | 64 ++++++++++++
drivers/video/backlight/lm3630a_bl.c | 2 +-
drivers/video/backlight/lp855x_bl.c | 2 +-
drivers/video/backlight/lp8788_bl.c | 2 +-
drivers/video/backlight/pwm_bl.c | 4 +-
drivers/video/fbdev/ssd1307fb.c | 3 +-
include/dt-bindings/pwm/pwm.h | 4 +
include/linux/pwm.h | 90 +++++++++++++++--
54 files changed, 402 insertions(+), 222 deletions(-)
--
2.7.4
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