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Date:	Sat, 13 Dec 2014 11:56:11 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Jaewon Kim <jaewon02.kim@...sung.com>
Cc:	Kukjin Kim <kgene.kim@...sung.com>, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, linux-input@...r.kernel.org,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Hyunhee Kim <hyunhee.kim@...sung.com>
Subject: Re: [PATCH v6 1/2] Input: add regulator haptic driver

Hi Jaewon,

On Fri, Dec 12, 2014 at 07:32:28PM +0900, Jaewon Kim wrote:
> This patch adds support for haptic driver controlled by
> voltage of regulator. And this driver support for
> Force Feedback interface from input framework
> 
> Signed-off-by: Jaewon Kim <jaewon02.kim@...sung.com>
> Signed-off-by: Hyunhee Kim <hyunhee.kim@...sung.com>
> Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
> Tested-by: Chanwoo Choi <cw00.choi@...sung.com>
> Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>
> Reviewed-by: Pankaj Dubey <pankaj.dubey@...sung.com>
> ---
>  .../devicetree/bindings/input/regulator-haptic.txt |   21 ++
>  drivers/input/misc/Kconfig                         |   11 +
>  drivers/input/misc/Makefile                        |    1 +
>  drivers/input/misc/regulator-haptic.c              |  259 ++++++++++++++++++++
>  include/linux/input/regulator-haptic.h             |   31 +++
>  5 files changed, 323 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/regulator-haptic.txt
>  create mode 100644 drivers/input/misc/regulator-haptic.c
>  create mode 100644 include/linux/input/regulator-haptic.h
> 
> diff --git a/Documentation/devicetree/bindings/input/regulator-haptic.txt b/Documentation/devicetree/bindings/input/regulator-haptic.txt
> new file mode 100644
> index 0000000..3ed1c7e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/regulator-haptic.txt
> @@ -0,0 +1,21 @@
> +* Regulator Haptic Device Tree Bindings
> +
> +Required Properties:
> + - compatible : Should be "regulator-haptic"
> + - haptic-supply : Power supply to the haptic motor.
> +	[*] refer Documentation/devicetree/bindings/regulator/regulator.txt
> +
> + - max-microvolt : The maximum voltage value supplied to the haptic motor.
> +		[The unit of the voltage is a micro]
> +
> + - min-microvolt : The minimum voltage value supplied to the haptic motor.
> +		[The unit of the voltage is a micro]
> +
> +Example:
> +
> +	haptics {
> +		compatible = "regulator-haptic";
> +		haptic-supply = <&motor_regulator>;
> +		max-microvolt = <2700000>;
> +		min-microvolt = <1100000>;
> +	};
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 23297ab..e5e556d 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -394,6 +394,17 @@ config INPUT_CM109
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called cm109.
>  
> +config INPUT_REGULATOR_HAPTIC
> +	tristate "regulator haptics support"
> +	select INPUT_FF_MEMLESS
> +	help
> +	  This option enables device driver support for the haptic controlled
> +	  by regulator. This driver supports ff-memless interface
> +	  from input framework.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called regulator-haptic.
> +
>  config INPUT_RETU_PWRBUTTON
>  	tristate "Retu Power button Driver"
>  	depends on MFD_RETU
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index 19c7603..1f135af 100644
> --- a/drivers/input/misc/Makefile
> +++ b/drivers/input/misc/Makefile
> @@ -53,6 +53,7 @@ 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_RB532_BUTTON)	+= rb532_button.o
> +obj-$(CONFIG_INPUT_REGULATOR_HAPTIC)	+= regulator-haptic.o
>  obj-$(CONFIG_INPUT_RETU_PWRBUTTON)	+= retu-pwrbutton.o
>  obj-$(CONFIG_INPUT_GPIO_ROTARY_ENCODER)	+= rotary_encoder.o
>  obj-$(CONFIG_INPUT_SGI_BTNS)		+= sgi_btns.o
> diff --git a/drivers/input/misc/regulator-haptic.c b/drivers/input/misc/regulator-haptic.c
> new file mode 100644
> index 0000000..2fa94bc
> --- /dev/null
> +++ b/drivers/input/misc/regulator-haptic.c
> @@ -0,0 +1,259 @@
> +/*
> + * Regulator haptic driver
> + *
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Author: Jaewon Kim <jaewon02.kim@...sung.com>
> + * Author: Hyunhee Kim <hyunhee.kim@...sung.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/input.h>
> +#include <linux/input/regulator-haptic.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#define MAX_MAGNITUDE_SHIFT	16
> +
> +struct regulator_haptic {
> +	struct device *dev;
> +	struct input_dev *input_dev;
> +	struct regulator *regulator;
> +
> +	struct work_struct work;
> +	struct mutex mutex;
> +
> +	bool enabled;
> +	bool suspend_state;
> +	unsigned int max_volt;
> +	unsigned int min_volt;
> +	unsigned int intensity;
> +	unsigned int magnitude;
> +};
> +
> +static void regulator_haptic_enable(struct regulator_haptic *haptic, bool state)
> +{
> +	int error;
> +
> +	if (haptic->enabled == state)
> +		return;
> +
> +	if (state)
> +		error = regulator_enable(haptic->regulator);
> +	else
> +		error = regulator_disable(haptic->regulator);
> +	if (error) {

Hmm, maybe:

	error = state ? regulator_enable(haptic->regulator) :
			regulator_disable(haptic->regulator);
	if (error)
		...

> +		dev_err(haptic->dev, "cannot enable regulator\n");
> +		return;
> +	}
> +
> +	haptic->enabled = state;
> +}
> +
> +static void regulator_haptic_work(struct work_struct *work)
> +{
> +	struct regulator_haptic *haptic = container_of(work,
> +					struct regulator_haptic, work);
> +	int error;
> +
> +	if (haptic->suspend_state)
> +		return;
> +

Why is this check outside of mutex?

> +	mutex_lock(&haptic->mutex);
> +
> +	error = regulator_set_voltage(haptic->regulator,
> +			haptic->intensity + haptic->min_volt, haptic->max_volt);
> +	if (error) {
> +		dev_err(haptic->dev, "cannot set regulator voltage\n");
> +		goto err;
> +	}
> +
> +	if (haptic->magnitude)
> +		regulator_haptic_enable(haptic, true);
> +	else
> +		regulator_haptic_enable(haptic, false);
> +
> +err:
> +	mutex_unlock(&haptic->mutex);
> +}
> +
> +static int regulator_haptic_play_effect(struct input_dev *input, void *data,
> +					struct ff_effect *effect)
> +{
> +	struct regulator_haptic *haptic = input_get_drvdata(input);
> +	u64 volt_mag_multi;
> +
> +	haptic->magnitude = effect->u.rumble.strong_magnitude;
> +	if (!haptic->magnitude)
> +		haptic->magnitude = effect->u.rumble.weak_magnitude;
> +
> +
> +	volt_mag_multi = (u64)(haptic->max_volt - haptic->min_volt) *
> +					haptic->magnitude;
> +	haptic->intensity = (unsigned int)(volt_mag_multi >>
> +					MAX_MAGNITUDE_SHIFT);
> +
> +	schedule_work(&haptic->work);
> +
> +	return 0;
> +}
> +
> +static void regulator_haptic_close(struct input_dev *input)
> +{
> +	struct regulator_haptic *haptic = input_get_drvdata(input);
> +
> +	cancel_work_sync(&haptic->work);
> +	regulator_haptic_enable(haptic, false);
> +}
> +
> +#ifdef CONFIG_OF
> +static int regulator_haptic_parse_dt(struct regulator_haptic *haptic)
> +{
> +	struct device_node *node = haptic->dev->of_node;
> +	int error;
> +
> +	error = of_property_read_u32(node, "max-microvolt", &haptic->max_volt);
> +	if (error) {
> +		dev_err(haptic->dev, "cannot parse max-microvolt\n");
> +		return error;
> +	}
> +
> +	error = of_property_read_u32(node, "min-microvolt", &haptic->min_volt);
> +	if (error) {
> +		dev_err(haptic->dev, "cannot parse min-microvolt\n");
> +		return error;
> +	}
> +
> +	return 0;
> +}
> +#else
> +static int regulator_haptic_parse_dt(struct regulator_haptic *haptic)
> +{
> +	return 0;

This does not seem right. If you do not have platform data and CONFOG_OF
is disabled you can't continue initialization.

> +}
> +#endif /* CONFIG_OF */
> +
> +static int regulator_haptic_probe(struct platform_device *pdev)
> +{
> +	struct regulator_haptic *haptic;
> +	struct regulator_haptic_data *data = dev_get_platdata(&pdev->dev);
> +	struct input_dev *input_dev;
> +	int error;
> +
> +	haptic = devm_kzalloc(&pdev->dev, sizeof(*haptic), GFP_KERNEL);
> +	if (!haptic)
> +		return -ENOMEM;
> +
> +	haptic->dev = &pdev->dev;
> +	haptic->enabled = false;
> +	haptic->suspend_state = false;
> +	mutex_init(&haptic->mutex);
> +	INIT_WORK(&haptic->work, regulator_haptic_work);
> +
> +	if (!data) {
> +		if (pdev->dev.of_node) {

I'd rather we moved check for presence of of_node into
regulator_haptic_parse_dt().


> +			error = regulator_haptic_parse_dt(haptic);
> +			if (error) {
> +				dev_err(&pdev->dev, "failed to parse device tree\n");
> +				return error;
> +			}
> +		} else {
> +			dev_err(&pdev->dev, "failed to get platdata\n");
> +			return -EINVAL;
> +		}
> +	} else {
> +		haptic->regulator = data->regulator;

What is the point of having regulator in platform data and doing
assignment here if you are going to clobber it a few lines down?

> +		haptic->max_volt = data->max_volt;
> +		haptic->min_volt = data->min_volt;
> +	}
> +
> +	haptic->regulator = devm_regulator_get_exclusive(&pdev->dev, "haptic");
> +	if (IS_ERR(haptic->regulator)) {
> +		dev_err(&pdev->dev, "failed to get regulator\n");
> +		return PTR_ERR(haptic->regulator);
> +	}
> +
> +	input_dev = devm_input_allocate_device(&pdev->dev);
> +	if (!input_dev)
> +		return  -ENOMEM;

Nit: extra space between return and error value.

> +
> +	haptic->input_dev = input_dev;
> +	haptic->input_dev->name = "regulator-haptic";
> +	haptic->input_dev->dev.parent = &pdev->dev;
> +	haptic->input_dev->close = regulator_haptic_close;
> +	input_set_drvdata(haptic->input_dev, haptic);
> +	input_set_capability(haptic->input_dev, EV_FF, FF_RUMBLE);
> +
> +	error = input_ff_create_memless(input_dev, NULL,
> +			      regulator_haptic_play_effect);
> +	if (error) {
> +		dev_err(&pdev->dev, "failed to create force-feedback\n");
> +		return error;
> +	}
> +
> +	error = input_register_device(haptic->input_dev);
> +	if (error) {
> +		dev_err(&pdev->dev, "failed to register input device\n");
> +		return error;
> +	}
> +
> +	platform_set_drvdata(pdev, haptic);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused regulator_haptic_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
> +
> +	mutex_lock(&haptic->mutex);
> +	if (haptic->enabled) {
> +		regulator_haptic_enable(haptic, false);
> +		haptic->suspend_state = true;

Why do we only set suspend_state if an effect was playing? I think we
should always indicate that the device is suspended so that we do not
try to start playing another effect - while it is true that normally
effects are played by request from userspace which should be frozen by
now, it is theoretically possible to trigger an effect from kernel as
well.

> +	}
> +	mutex_unlock(&haptic->mutex);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused regulator_haptic_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct regulator_haptic *haptic = platform_get_drvdata(pdev);
> +
> +	if (haptic->suspend_state) {

I think you should be gating enabling regulator not on suspend_state but
rather non-zero magnitude. And also lock the mutex to make absolutely
sure you are not racing with work item.

> +		regulator_haptic_enable(haptic, true);
> +		haptic->suspend_state = false;
> +	}
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(regulator_haptic_pm_ops,
> +		regulator_haptic_suspend, regulator_haptic_resume);
> +
> +static struct of_device_id regulator_haptic_dt_match[] = {
> +	{ .compatible = "regulator-haptic" },
> +	{ /* sentinel */ },
> +};
> +
> +static struct platform_driver regulator_haptic_driver = {
> +	.probe		= regulator_haptic_probe,
> +	.driver		= {
> +		.name		= "regulator-haptic",
> +		.of_match_table = regulator_haptic_dt_match,
> +		.pm		= &regulator_haptic_pm_ops,
> +	},
> +};
> +module_platform_driver(regulator_haptic_driver);
> +
> +MODULE_AUTHOR("Jaewon Kim <jaewon02.kim@...sung.com>");
> +MODULE_AUTHOR("Hyunhee Kim <hyunhee.kim@...sung.com>");
> +MODULE_DESCRIPTION("Regulator haptic driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/input/regulator-haptic.h b/include/linux/input/regulator-haptic.h
> new file mode 100644
> index 0000000..05ae038
> --- /dev/null
> +++ b/include/linux/input/regulator-haptic.h

Hmm, move it to include/linux/platform-data/ maybe?

> @@ -0,0 +1,31 @@
> +/*
> + * Regulator Haptic Platform Data
> + *
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Author: Jaewon Kim <jaewon02.kim@...sung.com>
> + * Author: Hyunhee Kim <hyunhee.kim@...sung.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef _REGULATOR_HAPTIC_H
> +#define _REGULATOR_HAPTIC_H
> +
> +/*
> + * struct regulator_haptic_data - Platform device data
> + *
> + * @regulator: Power supply to the haptic motor
> + * @max_volt: maximum voltage value supplied to the haptic motor.
> + * 		<The unit of the voltage is a micro>
> + * @min_volt: minimum voltage value supplied to the haptic motor.
> + * 		<The unit of the voltage is a micro>
> + */
> +struct regulator_haptic_data {
> +	struct regulator *regulator;
> +	unsigned int max_volt;
> +	unsigned int min_volt;
> +};
> +
> +#endif /* _REGULATOR_HAPTIC_H */
> -- 
> 1.7.9.5
> 

Thanks.

-- 
Dmitry
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