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[PATCHv4 0/3] PWM Vibrator driver

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  [PATCHv4 0/3] PWM Vibrator driver Sebastian Reichel <sebastian.reichel@collabora.co.uk> - 2017-07-14 12:10 +0200
    [PATCHv4 2/3] Input: pwm-vibra: new driver Sebastian Reichel <sebastian.reichel@collabora.co.uk> - 2017-07-14 12:10 +0200

#1687226 — [PATCHv4 0/3] PWM Vibrator driver

Hi,

The Motorola Droid 4 has a vibrator, that is connected
to two GPIOs. Motorola's stock kernel names them vib_en
and vib_dir, which probably stand for vibrator_enable
and vibrator_direction. In their stock kernel both GPIOs
are toggled using a hrtimer and a custom vibrator "misc"
device is provided to userspace.

Thankfully the hardware designers the used GPIOs can
also be used from OMAP's dmtimers, so that they can
be driven as PWM output instead saving some CPU cycles
(and code).

The driver is loosely based on an old patch from Dmitry,
that I found in the internet(tm) [0]. Since PATCHv4 the
Droid 4 also uses the generic PWM compatible and the
one specific to Motorola has been dropped.

Also I wrote a small tool to test the vibrator running
at different strength levels, since fftest(1) used a
fixed one.

Changes since PATCHv3:
 * Fix kernel doc comment
 * Use switch for error handling of direction pwm
 * Drop spin_lock_irqsave in suspend/resume handler
 * Drop Droid 4 specific code & binding
 * Add direction-duty-cycle-ns DT property
 * Dropped Tested-by due to restructuring
Changes since PATCHv2:
 * Add Kconfig dependency on INPUT_FF_MEMLESS
 * Add Tested-by from Tiny Lindgren
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

[0] https://lkml.org/lkml/2012/4/10/41
[1] https://git.collabora.com/cgit/user/sre/rumble-test.git/plain/rumble-test.c

-- Sebastian

Sebastian Reichel (3):
  dt-bindings: input: add pwm-vibrator
  Input: pwm-vibra: new driver
  ARM: dts: omap4-droid4: Add vibrator

 .../devicetree/bindings/input/pwm-vibrator.txt     |  66 +++++
 arch/arm/boot/dts/omap4-droid4-xt894.dts           |  40 +++
 drivers/input/misc/Kconfig                         |  12 +
 drivers/input/misc/Makefile                        |   1 +
 drivers/input/misc/pwm-vibra.c                     | 267 +++++++++++++++++++++
 5 files changed, 386 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/pwm-vibrator.txt
 create mode 100644 drivers/input/misc/pwm-vibra.c

-- 
2.13.2

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#1687230 — [PATCHv4 2/3] Input: pwm-vibra: new driver

Provide a simple driver for PWM controllable vibrators.
It will be used by Motorola Droid 4.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
---
 drivers/input/misc/Kconfig     |  12 ++
 drivers/input/misc/Makefile    |   1 +
 drivers/input/misc/pwm-vibra.c | 267 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 280 insertions(+)
 create mode 100644 drivers/input/misc/pwm-vibra.c

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 3872488c3fd7..7bb7285c4722 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -581,6 +581,18 @@ 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 b923a9828c88..36ea14997b40 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -59,6 +59,7 @@ 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..55da191ae550
--- /dev/null
+++ b/drivers/input/misc/pwm-vibra.c
@@ -0,0 +1,267 @@
+/*
+ *  PWM vibrator driver
+ *
+ *  Copyright (C) 2017 Collabora Ltd.
+ *
+ *  Based on previous work from:
+ *  Copyright (C) 2012 Dmitry Torokhov <dmitry.torokhov@gmail.com>
+ *
+ *  Based on PWM beeper driver:
+ *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.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.
+ */
+
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+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;
+	u32 direction_duty_cycle;
+};
+
+static int pwm_vibrator_start(struct pwm_vibrator *vibrator)
+{
+	struct device *pdev = vibrator->input->dev.parent;
+	struct pwm_state state;
+	int err;
+
+	err = regulator_enable(vibrator->vcc);
+	if (err) {
+		dev_err(pdev, "failed to enable regulator: %d", err);
+		return err;
+	}
+
+	pwm_get_state(vibrator->pwm, &state);
+	pwm_set_relative_duty_cycle(&state, vibrator->level, 0xffff);
+	state.enabled = true;
+
+	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.duty_cycle = vibrator->direction_duty_cycle;
+		state.enabled = true;
+
+		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)
+{
+	regulator_disable(vibrator->vcc);
+
+	if (vibrator->pwm_dir)
+		pwm_disable(vibrator->pwm_dir);
+	pwm_disable(vibrator->pwm);
+}
+
+static void pwm_vibrator_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 pwm_state state;
+	int err;
+
+	vibrator = devm_kzalloc(&pdev->dev, sizeof(*vibrator), GFP_KERNEL);
+	if (!vibrator)
+		return -ENOMEM;
+
+	vibrator->input = devm_input_allocate_device(&pdev->dev);
+	if (!vibrator->input)
+		return -ENOMEM;
+
+	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, pwm_vibrator_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);
+	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;
+		}
+
+		vibrator->direction_duty_cycle =
+			pwm_get_period(vibrator->pwm_dir) / 2;
+		device_property_read_u32(&pdev->dev, "direction-duty-cycle-ns",
+					 &vibrator->direction_duty_cycle);
+		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->input->name = "pwm-vibrator";
+	vibrator->input->id.bustype = BUS_HOST;
+	vibrator->input->dev.parent = &pdev->dev;
+	vibrator->input->close = pwm_vibrator_close;
+
+	input_set_drvdata(vibrator->input, vibrator);
+	input_set_capability(vibrator->input, EV_FF, FF_RUMBLE);
+
+	err = input_ff_create_memless(vibrator->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(vibrator->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 pwm_vibrator *vibrator = dev_get_drvdata(dev);
+
+	cancel_work_sync(&vibrator->play_work);
+	if (vibrator->level)
+		pwm_vibrator_stop(vibrator);
+
+	return 0;
+}
+
+static int __maybe_unused pwm_vibrator_resume(struct device *dev)
+{
+	struct pwm_vibrator *vibrator = dev_get_drvdata(dev);
+
+	if (vibrator->level)
+		pwm_vibrator_start(vibrator);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(pwm_vibrator_pm_ops,
+			 pwm_vibrator_suspend, pwm_vibrator_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pwm_vibra_dt_match_table[] = {
+	{ .compatible = "pwm-vibrator" },
+	{},
+};
+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@kernel.org>");
+MODULE_DESCRIPTION("PWM vibrator driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:pwm-vibrator");
-- 
2.13.2

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