Date:   Sun, 7 May 2017 14:38:00 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Sebastian Reichel <sebastian.reichel@...labora.co.uk>
Cc:     Sebastian Reichel <sre@...nel.org>,
        Tony Lindgren <tony@...mide.com>,
        Rob Herring <robh+dt@...nel.org>, linux-input@...r.kernel.org,
        linux-omap@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 1/2] Input: pwm-vibra: new driver

Hi Sebastian,

On Fri, May 05, 2017 at 11:28:22AM +0200, Sebastian Reichel wrote:
> Provide a simple driver for PWM controllable vibrators. It
> will be used by Motorola Droid 4.
> 
> Tested-by: Tony Lindgren <tony@...mide.com>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.co.uk>
> ---
> Changes since PATCHv1:
>  - move driver removal code to input->close function
>  - mark PM functions __maybe_unused and drop #ifdef CONFIG_PM_SLEEP
>  - remove duplicate NULL check for vibrator in probe function
>  - cancel work in suspend function
> Changes since PATCHv2:
>  - Add Kconfig dependency on INPUT_FF_MEMLESS
>  - Add Tested-by from Tiny Lindgren
> ---
>  .../devicetree/bindings/input/pwm-vibrator.txt     |  60 ++++
>  drivers/input/misc/Kconfig                         |  12 +
>  drivers/input/misc/Makefile                        |   1 +
>  drivers/input/misc/pwm-vibra.c                     | 343 +++++++++++++++++++++
>  4 files changed, 416 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/pwm-vibrator.txt
>  create mode 100644 drivers/input/misc/pwm-vibra.c
> 
> diff --git a/Documentation/devicetree/bindings/input/pwm-vibrator.txt b/Documentation/devicetree/bindings/input/pwm-vibrator.txt
> new file mode 100644
> index 000000000000..c35be4691366
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/pwm-vibrator.txt
> @@ -0,0 +1,60 @@
> +* PWM vibrator device tree bindings
> +
> +Registers a PWM device as vibrator.
> +
> +Required properties:
> +- compatible: should be
> +  * "pwm-vibrator"
> +    For vibrators controlled using the PWM channel's duty cycle (higher duty means
> +    the vibrator becomes stronger).
> +  * "motorola,mapphone-pwm-vibrator"
> +     For vibrator found in Motorola Droid 4. This vibrator generates a pulse for
> +     every rising edge, so its controlled using a duty cycle of 50% and changing
> +     the period time.
> +- pwm-names: Should contain "enable" and optionally "direction"
> +- pwms: Should contain a PWM handle for each entry in pwm-names
> +
> +Example from Motorola Droid 4:
> +
> +&omap4_pmx_core {
> +	vibrator_direction_pin: pinmux_vibrator_direction_pin {
> +		pinctrl-single,pins = <
> +		OMAP4_IOPAD(0x1ce, PIN_OUTPUT | MUX_MODE1) /* dmtimer8_pwm_evt (gpio_27) */
> +		>;
> +	};
> +
> +	vibrator_enable_pin: pinmux_vibrator_enable_pin {
> +		pinctrl-single,pins = <
> +		OMAP4_IOPAD(0X1d0, PIN_OUTPUT | MUX_MODE1) /* dmtimer9_pwm_evt (gpio_28) */
> +		>;
> +	};
> +};
> +
> +/ {
> +	pwm8: dmtimer-pwm {
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&vibrator_direction_pin>;
> +
> +		compatible = "ti,omap-dmtimer-pwm";
> +		#pwm-cells = <3>;
> +		ti,timers = <&timer8>;
> +		ti,clock-source = <0x01>;
> +	};
> +
> +	pwm9: dmtimer-pwm {
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&vibrator_enable_pin>;
> +
> +		compatible = "ti,omap-dmtimer-pwm";
> +		#pwm-cells = <3>;
> +		ti,timers = <&timer9>;
> +		ti,clock-source = <0x01>;
> +	};
> +
> +	vibrator {
> +		compatible = "pwm-vibrator";
> +		pwms = <&pwm8 0 1000000000 0>,
> +		       <&pwm9 0 1000000000 0>;
> +		pwm-names = "enable", "direction";
> +	};
> +};
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 5b6c52210d20..95cc4ed56980 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -571,6 +571,18 @@ config INPUT_PWM_BEEPER
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called pwm-beeper.
>  
> +config INPUT_PWM_VIBRA
> +	tristate "PWM vibrator support"
> +	depends on PWM
> +	depends on INPUT_FF_MEMLESS
> +	help
> +	  Say Y here to get support for PWM based vibrator devices.
> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called pwm-vibra.
> +
>  config INPUT_GPIO_ROTARY_ENCODER
>  	tristate "Rotary encoders connected to GPIO pins"
>  	depends on GPIOLIB || COMPILE_TEST
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index b10523f2878e..9a6517f5458c 100644
> --- a/drivers/input/misc/Makefile
> +++ b/drivers/input/misc/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_INPUT_PM8XXX_VIBRATOR)	+= pm8xxx-vibrator.o
>  obj-$(CONFIG_INPUT_PMIC8XXX_PWRKEY)	+= pmic8xxx-pwrkey.o
>  obj-$(CONFIG_INPUT_POWERMATE)		+= powermate.o
>  obj-$(CONFIG_INPUT_PWM_BEEPER)		+= pwm-beeper.o
> +obj-$(CONFIG_INPUT_PWM_VIBRA)		+= pwm-vibra.o
>  obj-$(CONFIG_INPUT_RB532_BUTTON)	+= rb532_button.o
>  obj-$(CONFIG_INPUT_REGULATOR_HAPTIC)	+= regulator-haptic.o
>  obj-$(CONFIG_INPUT_RETU_PWRBUTTON)	+= retu-pwrbutton.o
> diff --git a/drivers/input/misc/pwm-vibra.c b/drivers/input/misc/pwm-vibra.c
> new file mode 100644
> index 000000000000..878a483f93ff
> --- /dev/null
> +++ b/drivers/input/misc/pwm-vibra.c
> @@ -0,0 +1,343 @@
> +/*
> + *  PWM vibrator driver
> + *
> + *  Copyright (C) 2017 Collabora Ltd.
> + *
> + *  Based on previous work from:
> + *  Copyright (C) 2012 Dmitry Torokhov <dmitry.torokhov@...il.com>
> + *
> + *  Based on PWM beeper driver:
> + *  Copyright (C) 2010, Lars-Peter Clausen <lars@...afoo.de>
> + *
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under  the terms of the GNU General  Public License as published by the
> + *  Free Software Foundation;  either version 2 of the License, or (at your
> + *  option) any later version.
> + */
> +
> +#define DEBUG

I do not think this is needed.

> +
> +#include <linux/input.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +/**

This is not kernel doc, so no "/**".

> + * Motorola Droid 4 (also known as mapphone), has a vibrator, which pulses
> + * 1x on rising edge. Increasing the pwm period results in more pulses per
> + * second, but reduces intensity. There is also a second channel to control
> + * the vibrator's rotation direction to increase effect. The following
> + * numbers were determined manually. Going below 12.5 Hz means, clearly
> + * noticeable pauses and at 30 Hz the vibration is just barely noticable
> + * anymore.
> + */
> +#define MAPPHONE_MIN_FREQ 125 /* 12.5 Hz */
> +#define MAPPHONE_MAX_FREQ 300 /* 30.0 Hz */
> +
> +struct pwm_vibrator_hw {
> +	void (*setup_pwm)(u16 level, struct pwm_state *);
> +	void (*setup_pwm_dir)(u16 level, struct pwm_state *);
> +};
> +
> +struct pwm_vibrator {
> +	struct input_dev *input;
> +	struct pwm_device *pwm;
> +	struct pwm_device *pwm_dir;
> +	struct regulator *vcc;
> +
> +	struct work_struct play_work;
> +	u16 level;
> +
> +	const struct pwm_vibrator_hw *hw;
> +};
> +
> +static void pwm_vibrator_setup_generic(u16 level, struct pwm_state *state)
> +{
> +	/* period is configured by platform, duty cycle controls strength */
> +	pwm_set_relative_duty_cycle(state, level, 0xffff);
> +}
> +
> +static void pwm_vibrator_setup_dir_generic(u16 level, struct pwm_state *state)
> +{
> +	/* period is configured by platform, duty cycle controls strength */
> +	pwm_set_relative_duty_cycle(state, 50, 100);
> +}
> +
> +static struct pwm_vibrator_hw pwm_vib_hw_generic = {
> +	.setup_pwm = pwm_vibrator_setup_generic,
> +	.setup_pwm_dir = pwm_vibrator_setup_dir_generic,
> +};
> +
> +static void pwm_vibrator_setup_mapphone(u16 level, struct pwm_state *state)
> +{
> +	unsigned int freq;
> +
> +	/* convert [0, 0xffff] -> [MAPPHONE_MAX_FREQ, MAPPHONE_MIN_FREQ] */
> +	freq = 0xffff - level;
> +	freq *= MAPPHONE_MAX_FREQ - MAPPHONE_MIN_FREQ;
> +	freq /= 0xffff;
> +	freq += MAPPHONE_MIN_FREQ;
> +
> +	state->period = DIV_ROUND_CLOSEST_ULL((u64) NSEC_PER_SEC * 10, freq);
> +	pwm_set_relative_duty_cycle(state, 50, 100);
> +}
> +
> +static struct pwm_vibrator_hw pwm_vib_hw_mapphone = {
> +	.setup_pwm = pwm_vibrator_setup_mapphone,
> +	.setup_pwm_dir = pwm_vibrator_setup_mapphone,
> +};
> +
> +static int pwm_vibrator_start(struct pwm_vibrator *vibrator)
> +{
> +	struct device *pdev = vibrator->input->dev.parent;
> +	struct pwm_state state;
> +	int err;
> +
> +	dev_dbg(pdev, "start vibrator with level=0x%04x", vibrator->level);
> +
> +	err = regulator_enable(vibrator->vcc);
> +	if (err) {
> +		dev_err(pdev, "failed to enable regulator: %d", err);
> +		return err;
> +	}
> +
> +	pwm_get_state(vibrator->pwm, &state);
> +	state.enabled = true;
> +
> +	vibrator->hw->setup_pwm(vibrator->level, &state);
> +	dev_dbg(pdev, "period=%u", state.period);
> +
> +	err = pwm_apply_state(vibrator->pwm, &state);
> +	if (err) {
> +		dev_err(pdev, "failed to apply pwm state: %d", err);
> +		return err;
> +	}
> +
> +	if (vibrator->pwm_dir) {
> +		pwm_get_state(vibrator->pwm_dir, &state);
> +		state.enabled = true;
> +
> +		/* always control via period */
> +		vibrator->hw->setup_pwm_dir(vibrator->level, &state);
> +
> +		err = pwm_apply_state(vibrator->pwm_dir, &state);
> +		if (err) {
> +			dev_err(pdev, "failed to apply dir-pwm state: %d", err);
> +			pwm_disable(vibrator->pwm);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static void pwm_vibrator_stop(struct pwm_vibrator *vibrator)
> +{
> +	struct device *pdev = vibrator->input->dev.parent;
> +
> +	dev_dbg(pdev, "stop vibrator");
> +
> +	regulator_disable(vibrator->vcc);
> +
> +	if (vibrator->pwm_dir)
> +		pwm_disable(vibrator->pwm_dir);
> +	pwm_disable(vibrator->pwm);
> +}
> +
> +static void vibra_play_work(struct work_struct *work)
> +{
> +	struct pwm_vibrator *vibrator = container_of(work,
> +					struct pwm_vibrator, play_work);
> +
> +	if (vibrator->level)
> +		pwm_vibrator_start(vibrator);
> +	else
> +		pwm_vibrator_stop(vibrator);
> +}
> +
> +static int pwm_vibrator_play_effect(struct input_dev *dev, void *data,
> +				    struct ff_effect *effect)
> +{
> +	struct pwm_vibrator *vibrator = input_get_drvdata(dev);
> +
> +	vibrator->level = effect->u.rumble.strong_magnitude;
> +	if (!vibrator->level)
> +		vibrator->level = effect->u.rumble.weak_magnitude;
> +
> +	schedule_work(&vibrator->play_work);
> +
> +	return 0;
> +}
> +
> +static void pwm_vibrator_close(struct input_dev *input)
> +{
> +	struct pwm_vibrator *vibrator = input_get_drvdata(input);
> +
> +	cancel_work_sync(&vibrator->play_work);
> +	pwm_vibrator_stop(vibrator);
> +}
> +
> +static int pwm_vibrator_probe(struct platform_device *pdev)
> +{
> +	struct pwm_vibrator *vibrator;
> +	struct input_dev *input;
> +	struct pwm_state state;
> +	int err;
> +
> +	vibrator = devm_kzalloc(&pdev->dev, sizeof(*vibrator), GFP_KERNEL);
> +	if (!vibrator)
> +		return -ENOMEM;
> +
> +	input = devm_input_allocate_device(&pdev->dev);
> +	if (!input)
> +		return -ENOMEM;
> +
> +	vibrator->input = input;
> +
> +	vibrator->vcc = devm_regulator_get(&pdev->dev, "vcc");
> +	err = PTR_ERR_OR_ZERO(vibrator->vcc);
> +	if (err) {
> +		if (err != -EPROBE_DEFER)
> +			dev_err(&pdev->dev, "Failed to request regulator: %d",
> +				err);
> +		return err;
> +	}
> +
> +	vibrator->pwm = devm_pwm_get(&pdev->dev, "enable");
> +	err = PTR_ERR_OR_ZERO(vibrator->pwm);
> +	if (err) {
> +		if (err != -EPROBE_DEFER)
> +			dev_err(&pdev->dev, "Failed to request main pwm: %d",
> +				err);
> +		return err;
> +	}
> +
> +	INIT_WORK(&vibrator->play_work, vibra_play_work);
> +
> +	/* Sync up PWM state and ensure it is off. */
> +	pwm_init_state(vibrator->pwm, &state);
> +	state.enabled = false;
> +	err = pwm_apply_state(vibrator->pwm, &state);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to apply initial PWM state: %d",
> +			err);
> +		return err;
> +	}
> +
> +	vibrator->pwm_dir = devm_pwm_get(&pdev->dev, "direction");
> +	err = PTR_ERR_OR_ZERO(vibrator->pwm_dir);
> +	if (err == -ENODATA) {
> +		vibrator->pwm_dir = NULL;
> +	} else if (err == -EPROBE_DEFER) {
> +		return err;
> +	} else if (err) {
> +		dev_err(&pdev->dev, "Failed to request direction pwm: %d", err);
> +		return err;
> +	} else {
> +		/* Sync up PWM state and ensure it is off. */
> +		pwm_init_state(vibrator->pwm_dir, &state);
> +		state.enabled = false;
> +		err = pwm_apply_state(vibrator->pwm_dir, &state);
> +		if (err) {
> +			dev_err(&pdev->dev, "failed to apply initial PWM state: %d",
> +				err);
> +			return err;
> +		}
> +	}

I wonder if the above is not better with "switch":

	switch (err) {
	case 0:
		/* Sync up PWM state and ensure it is off. */
		pwm_init_state(vibrator->pwm_dir, &state);
		state.enabled = false;
		err = pwm_apply_state(vibrator->pwm_dir, &state);
		if (err) {
			dev_err(&pdev->dev,
				"failed to apply initial PWM state: %d", err);
			return err;
		}
		break;

	case -ENODATA:
		/* Direction PWM is optional */
		vibrator->pwm_dir = NULL;
		break;

	default:
		dev_err(&pdev->dev, "Failed to request direction pwm: %d", err);
		/* Fall through */

	case -EPROBE_DEFER:
		return err;
	}


> +
> +	vibrator->hw = of_device_get_match_data(&pdev->dev);
> +	if (!vibrator->hw)
> +		vibrator->hw = &pwm_vib_hw_generic;
> +
> +	input->name = "pwm-vibrator";
> +	input->id.bustype = BUS_HOST;
> +	input->dev.parent = &pdev->dev;
> +	input->close = pwm_vibrator_close;
> +
> +	input_set_drvdata(input, vibrator);
> +	input_set_capability(input, EV_FF, FF_RUMBLE);
> +
> +	err = input_ff_create_memless(input, NULL, pwm_vibrator_play_effect);
> +	if (err) {
> +		dev_err(&pdev->dev, "Couldn't create FF dev: %d", err);
> +		return err;
> +	}
> +
> +	err = input_register_device(input);
> +	if (err) {
> +		dev_err(&pdev->dev, "Couldn't register input dev: %d", err);
> +		return err;
> +	}
> +
> +	platform_set_drvdata(pdev, vibrator);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused pwm_vibrator_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct pwm_vibrator *vibrator = platform_get_drvdata(pdev);
> +	struct input_dev *input = vibrator->input;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&input->event_lock, flags);

Hmm, no, this is not goting to work. The original patch had a chance if
PWM was not sleeping, but with introduction of regulator and work this
definitely sleeps.

I think we should solve issue of events [not] being delivered during
suspend transition in input core, and simply drop spin_lock_irqsave()
here and in resume().

> +	cancel_work_sync(&vibrator->play_work);
> +	if (vibrator->level)
> +		pwm_vibrator_stop(vibrator);
> +	spin_unlock_irqrestore(&input->event_lock, flags);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused pwm_vibrator_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct pwm_vibrator *vibrator = platform_get_drvdata(pdev);
> +	struct input_dev *input = vibrator->input;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&input->event_lock, flags);
> +	if (vibrator->level)
> +		pwm_vibrator_start(vibrator);
> +	spin_unlock_irqrestore(&input->event_lock, flags);
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(pwm_vibrator_pm_ops,
> +			 pwm_vibrator_suspend, pwm_vibrator_resume);
> +
> +#ifdef CONFIG_OF
> +
> +#define PWM_VIB_COMPAT(of_compatible, cfg) {			\
> +			.compatible = of_compatible,		\
> +			.data = &cfg,	\
> +}
> +
> +static const struct of_device_id pwm_vibra_dt_match_table[] = {
> +	PWM_VIB_COMPAT("pwm-vibrator", pwm_vib_hw_generic),
> +	PWM_VIB_COMPAT("motorola,mapphone-pwm-vibrator", pwm_vib_hw_mapphone),
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, pwm_vibra_dt_match_table);
> +#endif
> +
> +static struct platform_driver pwm_vibrator_driver = {
> +	.probe	= pwm_vibrator_probe,
> +	.driver	= {
> +		.name	= "pwm-vibrator",
> +		.pm	= &pwm_vibrator_pm_ops,
> +		.of_match_table = of_match_ptr(pwm_vibra_dt_match_table),
> +	},
> +};
> +module_platform_driver(pwm_vibrator_driver);
> +
> +MODULE_AUTHOR("Sebastian Reichel <sre@...nel.org>");
> +MODULE_DESCRIPTION("PWM vibrator driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:pwm-vibrator");
> -- 
> 2.11.0
> 

Thanks.

-- 
Dmitry

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