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Message-ID: <e82d397f-81d4-31e3-a1e0-7c31c362b10d@microchip.com>
Date: Mon, 17 Dec 2018 14:06:03 +0000
From: <Claudiu.Beznea@...rochip.com>
To: <thierry.reding@...il.com>, <corbet@....net>,
<Nicolas.Ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
<Ludovic.Desroches@...rochip.com>, <robh@...nel.org>
CC: <linux-pwm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 0/9] extend PWM framework to support PWM modes
Please ignore this one, the number of patches in cover letter is wrong: 0/9
should be 0/6.
Thank you,
Claudiu Beznea
On 17.12.2018 16:03, Claudiu Beznea - M18063 wrote:
> From: Claudiu Beznea <claudiu.beznea@...rochip.com>
>
> Hi,
>
> This series extends PWM framework with PWM modes.
>
> The current patch series add the following PWM modes:
> - PWM mode normal
> - PWM mode complementary
> - PWM mode push-pull
>
> In the following description PWMx_y refers to output y of PWM with ID x.
>
> Normal mode - for PWM channels with one output; output waveforms looks like
> this:
> __ __ __ __
> PWMx __| |____| |____| |____| |__
> ^ ^ ^ ^
>
> Where '^' specifies the beginning of a period.
>
> Since PWMs with more than one output per channel could be used as one
> output PWM the normal mode is the default mode for all PWMs (if not specified
> otherwise).
>
> Complementary mode - for PWM channels with two outputs; output waveforms
> for a PWM channel in complementary mode looks line this:
> __ __ __ __
> PWMx_0 __| |____| |____| |____| |__
> __ ____ ____ ____ __
> PWMx_1 |__| |__| |__| |__|
> ^ ^ ^ ^
>
> Where '^' specifies the beginning of a period.
>
> Push-pull mode - for PWM channels with two outputs; output waveforms for a
> PWM channel in push-pull mode with normal polarity looks like this:
> __ __
> PWMx_0 __| |____________| |__________
> __ __
> PWMx_1 __________| |____________| |__
> ^ ^ ^ ^
>
> If polarity is inversed:
> __ ____________ __________
> PWMx_0 |__| |__|
> __________ ____________ __
> PWMx_1 |__| |__|
> ^ ^ ^ ^
>
> Where '^' specifies the beginning of a period.
>
> The PWM working modes are per PWM channel registered as PWM's capabilities.
> The driver registers itself to PWM core a get_caps() function, in
> struct pwm_ops, that will be used by PWM core to retrieve PWM capabilities.
> If this function is not registered in driver's probe, a default function
> will be used to retrieve PWM capabilities. Currently, the default
> capabilities includes only PWM normal mode.
>
> PWM state has been updated to keep PWM mode. PWM mode could be configured
> via sysfs. pwm_apply_state() will do the preliminary validation for PWM mode
> to be applied.
>
> In sysfs, user could get PWM modes by reading mode file of PWM device:
> root@...a5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# ls -l
> total 0
> -r--r--r-- 1 root root 4096 Oct 11 18:08 capture
> -rw-r--r-- 1 root root 4096 Oct 11 18:14 duty_cycle
> -rw-r--r-- 1 root root 4096 Oct 11 18:11 enable
> -rw-r--r-- 1 root root 4096 Oct 11 18:14 mode
> -rw-r--r-- 1 root root 4096 Oct 11 18:09 period
> -rw-r--r-- 1 root root 4096 Oct 11 18:14 polarity
> drwxr-xr-x 2 root root 0 Oct 11 18:08 power
> -rw-r--r-- 1 root root 4096 Oct 11 18:08 uevent
> root@...a5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# cat mode
> normal complementary [push-pull]
>
> The mode enclosed in bracket is the currently active mode.
>
> The mode could be set, via sysfs, by writing to mode file one of the modes
> displayed at read:
> root@...a5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# echo normal > mode
> root@...a5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# cat mode
> [normal] complementary push-pull
>
> The PWM push-pull mode could be usefull in applications like half bridge
> converters (see [1], page 2126).
>
> This series also add PWM modes support for Atmel/Microchip SoCs.
>
> Thank you,
> Claudiu Beznea
>
> [1] http://ww1.microchip.com/downloads/en/DeviceDoc/DS60001476B.pdf
>
> Changes in v6:
> - get rid of DT changes;
> - get rid of get_default_caps member of struct pwm_chip;
> - remove struct pwm_chip argument of pwm_get_caps(); caps are retrieved
> in the context of a PWM device and at this moment the chip should be valid;
> also, get rid of chip->ops check in pwm_get_caps();
> - rename pwm_mode_get_valid() function to pwm_get_default_modebit();
> - rename mode member of struct pwm_caps to modes_msk;
> - rename pwm_mode_valid() function to pwm_supports_mode() and rename
> its mode argument to modebit to emphasize what should be passed to it;
> - rename pwm_mode_desc() to pwm_get_mode_name() and avoid returning "invalid"
> string; pwm_get_mode_name() is called only with a valid modebit;
> - rename mode member of struct pwm_state to modebit to emphasize that it stores
> a bitmask;
> - use const arguments for pwm_get_default_modebit(), pwm_get_caps(),
> pwm_supports_mode() and get_caps() member of struct pwm_ops;
> - change return type of pwm_ops::get_caps() to int;
> - rename PWMC_MODE() macro to PWM_MODE_BIT();
> - rename PWMC_MODE_<mode-name>_BIT enum members to PWM_MODE_<mode-name>;
> - remove patches 2/9, 3/9, 4/9 from previous version since they were related
> to DT changes;
> - use PWMx_y naming in documentation to emphasize it is talked about output
> y of PWM x;
> - use 1/3 duty factor in waveforms from documentation patches;
> - use '^' to emphasize the beginning of a new period in documentation patches.
>
> Changes in v5:
> - solved kbuild errors by removing dummy functions for case where
> CONFIG_PWM is not defined; adopted this approach since the removed
> function are used only when CONFIG_PWM is defined (in PWM core
> and few drivers from drivers/pwm/ directory)
>
> Changes in v4:
> - removed changes related to pwm_config() as per maintainer proposals
> - added pwm_mode_get_valid() to retrieve a valid PWM mode fror PWM device
> instead of using BIT(ffs(caps.mode) - 1) and changed drivers to use
> pwm_mode_get_valid() instead of pwm_get_caps() + BIT(ffs(caps.mode) - 1)
> (patches 2, 3, 4 from this series)
> - renamed PWM_MODE() macro in PWMC_MODE() to avoid conflicts with
> pwm-sun4i.c driver ('C' stands for capability)
> - removed pwm_caps_valid() function
> - renamed PWM_DTMODE_COMPLEMENTARY and PWM_DTMODE_PUSH_PULL macros in
> PWM_MODE_COMPLEMENTARY and PWM_MODE_PUSH_PULL
>
> Changes in v3:
> - removed changes related to only one of_xlate function for all PWM drivers
> - switch to PWM capabilities per PWM channel nor per PWM chip
> - squash documentation and bindings patches as requeted by reviewer
> - introduced PWM_MODE(name) macro and used a bit enum for pwm modes
> - related to DT bindings, used flags cell also for PWM modes
> - updated of_xlate specific functions with "state->mode = mode;"
> instructions to avoid pwm_apply_state() failures
> - use available modes for PWM channel in pwm_config() by first calling
> pwm_get_caps() to get caps.modes
> - use loops through available modes in mode_store()/mode_show() and also in
> of_pwm_xlate_with_flags() instead of "if else" instructions; in this way,
> the addition of a new mode is independent of this code sections
> - use DTLI=1, DTHI=0 register settings to obtain push-pull mode waveforms
> for Atmel/Microchip PWM controller.
>
> 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 (9):
> pwm: extend PWM framework with PWM modes
> pwm: clps711x: populate PWM mode in of_xlate function
> pwm: cros-ec: populate PWM mode in of_xlate function
> pwm: pxa: populate PWM mode in of_xlate function
> pwm: add PWM modes
> pwm: atmel: add pwm capabilities
> pwm: add push-pull mode support
> pwm: add documentation for pwm push-pull mode
> pwm: atmel: add push-pull mode support
>
> Documentation/devicetree/bindings/pwm/pwm.txt | 11 ++-
> Documentation/pwm.txt | 42 ++++++++-
> drivers/pwm/core.c | 125 +++++++++++++++++++++++++-
> drivers/pwm/pwm-atmel.c | 118 +++++++++++++++++-------
> drivers/pwm/pwm-clps711x.c | 10 ++-
> drivers/pwm/pwm-cros-ec.c | 1 +
> drivers/pwm/pwm-pxa.c | 1 +
> drivers/pwm/sysfs.c | 61 +++++++++++++
> include/dt-bindings/pwm/pwm.h | 2 +
> include/linux/pwm.h | 64 +++++++++++++
> 10 files changed, 395 insertions(+), 40 deletions(-)
>
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