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    Subject[PATCH v2 00/16] extend PWM framework to support PWM modes
    Date
    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@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@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@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@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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