Input: add regulator haptic driver

This change adds support for haptic driver controlled by voltage of a
regulator. Userspace can control the device via Force Feedback interface
from input framework.

Signed-off-by: Jaewon Kim <[e-mail]>
Signed-off-by: Hyunhee Kim <[e-mail]>
Acked-by: Kyungmin Park <[e-mail]>
Tested-by: Chanwoo Choi <[e-mail]>
Reviewed-by: Chanwoo Choi <[e-mail]>
Reviewed-by: Pankaj Dubey <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/regulator-haptic.txt

···
+* 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>;
+	};

drivers/input/misc/Kconfig

···
 	  To compile this driver as a module, choose M here: the module will be
 	  called cm109.
 
+config INPUT_REGULATOR_HAPTIC
+	tristate "Regulator haptics support"
+	depends on REGULATOR
+	select INPUT_FF_MEMLESS
+	help
+	  This option enables device driver support for the haptic controlled
+	  by a 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

drivers/input/misc/Makefile

···
 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

drivers/input/misc/regulator-haptic.c

···
+/*
+ * Regulator haptic driver
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Jaewon Kim <[e-mail]>
+ * Author: Hyunhee Kim <[e-mail]>
+ *
+ * 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/module.h>
+#include <linux/of.h>
+#include <linux/platform_data/regulator-haptic.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 active;
+	bool suspended;
+
+	unsigned int max_volt;
+	unsigned int min_volt;
+	unsigned int magnitude;
+};
+
+static int regulator_haptic_toggle(struct regulator_haptic *haptic, bool on)
+{
+	int error;
+
+	if (haptic->active != on) {
+
+		error = on ? regulator_enable(haptic->regulator) :
+			     regulator_disable(haptic->regulator);
+		if (error) {
+			dev_err(haptic->dev,
+				"failed to switch regulator %s: %d\n",
+				on ? "on" : "off", error);
+			return error;
+		}
+
+		haptic->active = on;
+	}
+
+	return 0;
+}
+
+static int regulator_haptic_set_voltage(struct regulator_haptic *haptic,
+					 unsigned int magnitude)
+{
+	u64 volt_mag_multi;
+	unsigned int intensity;
+	int error;
+
+	volt_mag_multi = (u64)(haptic->max_volt - haptic->min_volt) * magnitude;
+	intensity = (unsigned int)(volt_mag_multi >> MAX_MAGNITUDE_SHIFT);
+
+	error = regulator_set_voltage(haptic->regulator,
+				      intensity + haptic->min_volt,
+				      haptic->max_volt);
+	if (error) {
+		dev_err(haptic->dev, "cannot set regulator voltage to %d: %d\n",
+			intensity + haptic->min_volt, error);
+		return error;
+	}
+
+	return 0;
+}
+
+static void regulator_haptic_work(struct work_struct *work)
+{
+	struct regulator_haptic *haptic = container_of(work,
+					struct regulator_haptic, work);
+	unsigned int magnitude;
+	int error;
+
+	mutex_lock(&haptic->mutex);
+
+	if (haptic->suspended)
+		goto out;
+
+	magnitude = ACCESS_ONCE(haptic->magnitude);
+
+	error = regulator_haptic_set_voltage(haptic, magnitude);
+	if (error)
+		goto out;
+
+	regulator_haptic_toggle(haptic, magnitude != 0);
+
+out:
+	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);
+
+	haptic->magnitude = effect->u.rumble.strong_magnitude;
+	if (!haptic->magnitude)
+		haptic->magnitude = effect->u.rumble.weak_magnitude;
+
+	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_set_voltage(haptic, 0);
+	regulator_haptic_toggle(haptic, false);
+}
+
+static int __maybe_unused
+regulator_haptic_parse_dt(struct device *dev, struct regulator_haptic *haptic)
+{
+	struct device_node *node;
+	int error;
+
+	node = dev->of_node;
+	if(!node) {
+		dev_err(dev, "Missing dveice tree data\n");
+		return -EINVAL;
+	}
+
+	error = of_property_read_u32(node, "max-microvolt", &haptic->max_volt);
+	if (error) {
+		dev_err(dev, "cannot parse max-microvolt\n");
+		return error;
+	}
+
+	error = of_property_read_u32(node, "min-microvolt", &haptic->min_volt);
+	if (error) {
+		dev_err(dev, "cannot parse min-microvolt\n");
+		return error;
+	}
+
+	return 0;
+}
+
+static int regulator_haptic_probe(struct platform_device *pdev)
+{
+	const struct regulator_haptic_data *pdata = dev_get_platdata(&pdev->dev);
+	struct regulator_haptic *haptic;
+	struct input_dev *input_dev;
+	int error;
+
+	haptic = devm_kzalloc(&pdev->dev, sizeof(*haptic), GFP_KERNEL);
+	if (!haptic)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, haptic);
+	haptic->dev = &pdev->dev;
+	mutex_init(&haptic->mutex);
+	INIT_WORK(&haptic->work, regulator_haptic_work);
+
+	if (pdata) {
+		haptic->max_volt = pdata->max_volt;
+		haptic->min_volt = pdata->min_volt;
+	} else if (IS_ENABLED(CONFIG_OF)) {
+		error = regulator_haptic_parse_dt(&pdev->dev, haptic);
+		if (error)
+			return error;
+	} else {
+		dev_err(&pdev->dev, "Missing platform data\n");
+		return -EINVAL;
+	}
+
+	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;
+
+	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;
+	}
+
+	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);
+	int error;
+
+	error = mutex_lock_interruptible(&haptic->mutex);
+	if (error)
+		return error;
+
+	regulator_haptic_set_voltage(haptic, 0);
+	regulator_haptic_toggle(haptic, false);
+
+	haptic->suspended = true;
+
+	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);
+	unsigned int magnitude;
+
+	mutex_lock(&haptic->mutex);
+
+	haptic->suspended = false;
+
+	magnitude = ACCESS_ONCE(haptic->magnitude);
+	if (magnitude) {
+		regulator_haptic_set_voltage(haptic, magnitude);
+		regulator_haptic_toggle(haptic, true);
+	}
+
+	mutex_unlock(&haptic->mutex);
+
+	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 <[e-mail]>");
+MODULE_AUTHOR("Hyunhee Kim <[e-mail]>");
+MODULE_DESCRIPTION("Regulator haptic driver");
+MODULE_LICENSE("GPL");

include/linux/platform_data/regulator-haptic.h

···
+/*
+ * Regulator Haptic Platform Data
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Jaewon Kim <[e-mail]>
+ * Author: Hyunhee Kim <[e-mail]>
+ *
+ * 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
+ *
+ * @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 {
+	unsigned int max_volt;
+	unsigned int min_volt;
+};
+
+#endif /* _REGULATOR_HAPTIC_H */