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    SubjectRe: [PATCH RESEND] LEDS-One-Shot-Timer-Trigger-implementation
    On Mon, Apr 09, 2012 at 04:40:29PM -0600, Shuah Khan wrote:
    > On Mon, 2012-04-09 at 13:42 -0700, Dmitry Torokhov wrote:
    > > On Mon, Apr 09, 2012 at 02:20:47PM -0600, Shuah Khan wrote:
    > > > On Mon, 2012-04-09 at 11:45 -0700, Dmitry Torokhov wrote:
    > > > > On Mon, Apr 09, 2012 at 12:16:05PM -0600, Shuah Khan wrote:
    > > > > > On Mon, 2012-04-09 at 10:37 -0700, Dmitry Torokhov wrote:
    > > > > > > On Mon, Apr 09, 2012 at 10:55:49AM -0600, Shuah Khan wrote:
    > > > > > > > On Sat, 2012-04-07 at 14:56 -0700, Dmitry Torokhov wrote:
    > > > > > > > > Hi Shuah,
    > > > > > > > >
    > > > > > > > > On Sat, Apr 07, 2012 at 08:13:44AM -0600, Shuah Khan wrote:
    > > > > > > > > >
    > > > > > > > > > > > +This feature will help implement vibrate functionality which requires one
    > > > > > > > > > > > +time activation of vibrate mode without a continuous vibrate on/off cycles.
    > > > > > > > > > >
    > > > > > > > > > > They make vibrating LED? ;)
    > > > > > > > > > >
    > > > > > > > > > > What's going on here? You're proposing to repurpose the LEDs code to
    > > > > > > > > > > drive vibration devices? Or some devices couple a LED with a vibration
    > > > > > > > > > > device?
    > > > > > > > > >
    > > > > > > > > > I owe you filling in the blanks type explanation. Let me describe the
    > > > > > > > > > use-case I am trying to address first. Vibrater function on phones is
    > > > > > > > > > implemented using PWM pins on SoC or PMIC. When there is no such
    > > > > > > > > > hardware present, a software solution is needed. Currently two drivers
    > > > > > > > > > timed-gpio and timed-output (under staging/android in Linux 3.3)
    > > > > > > > > > together implement the software vibrate feature. The main functionality
    > > > > > > > > > it implements is the one time enables of timer to prevent user space
    > > > > > > > > > crashes leaving the phone in vibrate mode causing the battery to drain.
    > > > > > > > > > leds as it is implemented currently, is not suitable to address this
    > > > > > > > > > use-case as it doesn't support one time enables.
    > > > > > > > >
    > > > > > > > > So why do not you use memoryless force feedback framework that other
    > > > > > > > > devices use (see drivers/input/misc/*vibra.c drivers).
    > > > > > > > >
    > > > > > > >
    > > > > > > > Dimitry,
    > > > > > > >
    > > > > > > > I took a look at these vibra* drivers. The three vibrate drivers are
    > > > > > > > chip-set specific. The use-case I have is a non-chip set approach to
    > > > > > > > address the use-case when vibrate hardware is not present. Are you
    > > > > > > > envisioning a generic approach using ff-memoryless infrastructure?
    > > > > > >
    > > > > > > Shuah,
    > > > > > >
    > > > > > > I guess I am confused now. You need some form of hardware to make your
    > > > > > > device to vibrate.
    > > > > > >
    > > > > > > What exactly are you trying to do? Are you trying to:
    > > > > > >
    > > > > > > 1. activate vibration on devices that can actually do it using LED
    > > > > > > interface, or
    > > > > > >
    > > > > > > 2. use LEDs as an alternative to vibrate on devices that can't
    > > > > > > physically vibrate?
    > > > > > >
    > > > > > > Thanks.
    > > > > >
    > > > > > What I meant by generic approach is a higher level interface that is not
    > > > > > tied too closely to the underlying hardware. Similar to the leds-pwm.c
    > > > > > and leds-gpio.c handle gpio and pwm based leds. The vibrate hardware in
    > > > > > my sue-case is a gpio based and could pwm based on some phones.
    > > > >
    > > > > Ok, so you need to add drivers/input/misc/gpio-vibrate.c and pwm-vibrate.c
    > > > > and then use FF to activate them. This way we have all vibrate
    > > > > implementation use one subsystem instead of splitting between
    > > > > input/led/whatever else people could come up with.
    > > > >
    > > > > Thanks.
    > > > >
    > > >
    > > > Dmitry,
    > > >
    > > > It is unfortunate that we have these two infrastructures evolve that has
    > > > a lot of overlap. Let me summarize the two alternatives first so we get
    > > > a feel for the work involved to address this use-case using ff and leds
    > > > frameworks:
    > > >
    > > > Alternative 1: using leds infrastructure
    > > >
    > > > Add new kernel interface to support one time enables. This will enable
    > > > existing gpio and pwm drivers to be used to implement vibrate.
    > > >
    > > > Alternative 2: using ff infrastructure
    > > >
    > > > Add new drivers gpio and pwm that use existing one time enable to
    > > > implement vibrate in a generic way.
    > > >
    > > > Does this sound right? From a quick glance it sounds like we can get to
    > > > the end goal quicker and in a simpler way with Alternative 1. However, I
    > > > might be missing longterm view. Any other alternatives we could explore?
    > > >
    > >
    > > For 1 you are forgetting "persuade current users of mainline vibrator
    > > drivers in kernel to adopt their drivers and userpace to LED framework"
    > > because we should try to provide single interface for a given function.
    > >
    > > Thanks.
    > >
    >
    > Dmitry,
    >
    > I can't argue against the user-space angle. Let me give more thought to
    > Alternative 2 and see if it indeed turns out to be more work. Thanks for
    > a good discussion.

    See if the following patch will make the decision a bit easier ;) It
    might need some love as I do not actually have the hardware.

    --
    Dmitry


    Input: add support for PWM-based vibrators

    From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

    Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
    ---

    drivers/input/misc/Kconfig | 11 ++
    drivers/input/misc/Makefile | 1
    drivers/input/misc/pwm-vibrator.c | 213 ++++++++++++++++++++++++++++++++++++
    include/linux/input/pwm-vibrator.h | 13 ++
    4 files changed, 238 insertions(+), 0 deletions(-)
    create mode 100644 drivers/input/misc/pwm-vibrator.c
    create mode 100644 include/linux/input/pwm-vibrator.h


    diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
    index ee077a4..913bdb8 100644
    --- a/drivers/input/misc/Kconfig
    +++ b/drivers/input/misc/Kconfig
    @@ -451,6 +451,17 @@ config INPUT_PWM_BEEPER
    To compile this driver as a module, choose M here: the module will be
    called pwm-beeper.

    +config INPUT_PWM_VIBRATOR
    + tristate "PWM vibrator support"
    + depends on HAVE_PWM
    + 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-vibrator.
    +
    config INPUT_GPIO_ROTARY_ENCODER
    tristate "Rotary encoders connected to GPIO pins"
    depends on GPIOLIB && GENERIC_GPIO
    diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
    index f55cdf4..e8b7643 100644
    --- a/drivers/input/misc/Makefile
    +++ b/drivers/input/misc/Makefile
    @@ -43,6 +43,7 @@ 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-$(CONFIG_INPUT_PWM_VIBRATOR) += pwm-vibrator.o
    obj-$(CONFIG_INPUT_RB532_BUTTON) += rb532_button.o
    obj-$(CONFIG_INPUT_GPIO_ROTARY_ENCODER) += rotary_encoder.o
    obj-$(CONFIG_INPUT_SGI_BTNS) += sgi_btns.o
    diff --git a/drivers/input/misc/pwm-vibrator.c b/drivers/input/misc/pwm-vibrator.c
    new file mode 100644
    index 0000000..c72bac9
    --- /dev/null
    +++ b/drivers/input/misc/pwm-vibrator.c
    @@ -0,0 +1,213 @@
    +/*
    + * PWM vibrator driver
    + *
    + * 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.
    + *
    + * You should have received a copy of the GNU General Public License along
    + * with this program; if not, write to the Free Software Foundation, Inc.,
    + * 675 Mass Ave, Cambridge, MA 02139, USA.
    + *
    + */
    +
    +#include <linux/input.h>
    +#include <linux/module.h>
    +#include <linux/kernel.h>
    +#include <linux/platform_device.h>
    +#include <linux/pwm.h>
    +#include <linux/slab.h>
    +#include <linux/input/pwm-vibrator.h>
    +
    +struct pwm_vibrator {
    + struct input_dev *input;
    + struct pwm_device *pwm;
    + unsigned int pwm_period;
    + unsigned int level;
    +};
    +
    +static int pwm_vibrator_start(struct pwm_vibrator *vibrator)
    +{
    + unsigned int duty = vibrator->pwm_period * vibrator->level / 100;
    + int error;
    +
    + error = pwm_config(vibrator->pwm, duty, vibrator->pwm_period);
    + if (error < 0)
    + return error;
    +
    + error = pwm_enable(vibrator->pwm);
    + if (error < 0)
    + return error;
    +
    + return 0;
    +}
    +
    +static void pwm_vibrator_stop(struct pwm_vibrator *vibrator)
    +{
    + pwm_config(vibrator->pwm, 0, 0);
    + pwm_disable(vibrator->pwm);
    +}
    +
    +static int pwm_vibrator_play_effect(struct input_dev *dev, void *data,
    + struct ff_effect *effect)
    +{
    + struct pwm_vibrator *vibrator = input_get_drvdata(dev);
    + int error;
    +
    + vibrator->level = effect->u.rumble.strong_magnitude;
    + if (!vibrator->level)
    + vibrator->level = effect->u.rumble.weak_magnitude;
    +
    + if (vibrator->level) {
    + error = pwm_vibrator_start(vibrator);
    + if (error) {
    + dev_err(vibrator->input->dev.parent,
    + "%s: pwm_vibrator_start failed, error: %d\n",
    + __func__, error);
    + return error;
    + }
    + } else {
    + pwm_vibrator_stop(vibrator);
    + }
    +
    + return 0;
    +}
    +
    +
    +static int __devinit pwm_vibrator_probe(struct platform_device *pdev)
    +{
    + const struct pwm_vibrator_platform_data *pdata;
    + struct pwm_vibrator *vibrator;
    + struct input_dev *input;
    + int error;
    +
    + pdata = pdev->dev.platform_data;
    + if (!pdata) {
    + dev_err(&pdev->dev, "Missing platform dat\n");
    + return -EINVAL;
    + }
    +
    + vibrator = kzalloc(sizeof(*vibrator), GFP_KERNEL);
    + input = input_allocate_device();
    + if (!vibrator || !input) {
    + error = -ENOMEM;
    + goto err_mem_free;
    + }
    +
    + vibrator->input = input;
    + vibrator->pwm_period = pdata->pwm_period;
    +
    + vibrator->pwm = pwm_request(pdata->pwm_id, "pwm vibrator");
    + if (IS_ERR(vibrator->pwm)) {
    + error = PTR_ERR(vibrator->pwm);
    + dev_err(&pdev->dev, "Failed to request pwm device: %d\n", error);
    + goto err_mem_free;
    + }
    +
    + input->name = "pwm-vibrator";
    + input->id.bustype = BUS_HOST;
    + input->dev.parent = &pdev->dev;
    +
    + input_set_drvdata(input, vibrator);
    + input_set_capability(input, EV_FF, FF_RUMBLE);
    +
    + error = input_ff_create_memless(input, NULL,
    + pwm_vibrator_play_effect);
    + if (error) {
    + dev_err(&pdev->dev,
    + "Unable to create FF device, error: %d\n",
    + error);
    + goto err_pwm_free;
    + }
    +
    + error = input_register_device(input);
    + if (error) {
    + dev_err(&pdev->dev, "Failed to register input device: %d\n", error);
    + goto err_pwm_free;
    + }
    +
    + platform_set_drvdata(pdev, vibrator);
    +
    + return 0;
    +
    +err_pwm_free:
    + pwm_free(vibrator->pwm);
    +err_mem_free:
    + input_free_device(vibrator->input);
    + kfree(vibrator);
    +
    + return error;
    +}
    +
    +static int __devexit pwm_vibrator_remove(struct platform_device *pdev)
    +{
    + struct pwm_vibrator *vibrator = platform_get_drvdata(pdev);
    +
    + platform_set_drvdata(pdev, NULL);
    +
    + input_unregister_device(vibrator->input);
    +
    + pwm_disable(vibrator->pwm);
    + pwm_free(vibrator->pwm);
    +
    + kfree(vibrator);
    +
    + return 0;
    +}
    +
    +#ifdef CONFIG_PM_SLEEP
    +static int 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);
    + if (vibrator->level)
    + pwm_vibrator_stop(vibrator);
    + spin_unlock_irqrestore(&input->event_lock, flags);
    +
    + return 0;
    +}
    +
    +static int 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;
    +}
    +#endif
    +
    +static SIMPLE_DEV_PM_OPS(pwm_vibrator_pm_ops,
    + pwm_vibrator_suspend, pwm_vibrator_resume);
    +
    +static struct platform_driver pwm_vibrator_driver = {
    + .probe = pwm_vibrator_probe,
    + .remove = __devexit_p(pwm_vibrator_remove),
    + .driver = {
    + .name = "pwm-vibrator",
    + .owner = THIS_MODULE,
    + .pm = &pwm_vibrator_pm_ops,
    + },
    +};
    +module_platform_driver(pwm_vibrator_driver);
    +
    +MODULE_AUTHOR("Dmitry Torokhov <dmitry.torokhov@gmail.com>");
    +MODULE_DESCRIPTION("PWM vibrator driver");
    +MODULE_LICENSE("GPL");
    +MODULE_ALIAS("platform:pwm-vibrator");
    diff --git a/include/linux/input/pwm-vibrator.h b/include/linux/input/pwm-vibrator.h
    new file mode 100644
    index 0000000..efe1f72
    --- /dev/null
    +++ b/include/linux/input/pwm-vibrator.h
    @@ -0,0 +1,13 @@
    +#ifndef __INPUT_PWM_VIBRATOR_H
    +#define __INPUT_PWM_VIBRATOR_H
    +
    +/*
    + * PWM vibrator driver data
    + */
    +
    +struct pwm_vibrator_platform_data {
    + unsigned int pwm_id;
    + unsigned int pwm_period;
    +};
    +
    +#endif

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