Date: Sat, 26 Apr 2014 15:07:01 +0200
From: Antonio Ospite <ao2@ao2.it>
To: Michal =?ISO-8859-1?Q?Mal=FD?= <madcatxster@devoid-pointer.net>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        dmitry.torokhov@gmail.com, jkosina@suse.cz, elias.vds@gmail.com,
        anssi.hannula@iki.fi, simon@mungewell.org
Subject: Re: [PATCH v3 01/24] input: Add ff-memless-next module
Message-Id: <20140426150701.8dc9dde837757b966d6c0e27@ao2.it>
In-Reply-To: <1398513696-12626-2-git-send-email-madcatxster@devoid-pointer.net>
References: <1398513696-12626-1-git-send-email-madcatxster@devoid-pointer.net>
	<1398513696-12626-2-git-send-email-madcatxster@devoid-pointer.net>
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Sender: linux-kernel-owner@vger.kernel.org

On Sat, 26 Apr 2014 13:57:38 +0200
Michal Mal? <madcatxster@devoid-pointer.net> wrote:

> Add ff-memless-next module
>

Hi Michal, what about adding the notes from 0/24 to this commit
message? This is the one which will actually get into the project
history. And perhaps hint briefly about the improvements also in the
commit message of 24/24?

> Signed-off-by: Michal Mal? <madcatxster@devoid-pointer.net>
> Tested-by: Elias Vanderstuyft <elias.vds@gmail.com>
> ---
>  drivers/input/Kconfig                 |   11 +
>  drivers/input/Makefile                |    1 +
>  drivers/input/ff-memless-next.c       | 1037 +++++++++++++++++++++++++++++++++
>  include/linux/input/ff-memless-next.h |  162 +++++
>  4 files changed, 1211 insertions(+)
>  create mode 100644 drivers/input/ff-memless-next.c
>  create mode 100644 include/linux/input/ff-memless-next.h
> 
> diff --git a/drivers/input/Kconfig b/drivers/input/Kconfig
> index a11ff74..3780962 100644
> --- a/drivers/input/Kconfig
> +++ b/drivers/input/Kconfig
> @@ -38,6 +38,17 @@ config INPUT_FF_MEMLESS
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ff-memless.
>  
> +config INPUT_FF_MEMLESS_NEXT
> +	tristate "New version of support for memoryless force-feedback devices"
> +	help
> +	  Say Y here to enable a new version of support for memoryless force
> +	  feedback devices.
> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ff-memless-next.
> +
>  config INPUT_POLLDEV
>  	tristate "Polled input device skeleton"
>  	help
> diff --git a/drivers/input/Makefile b/drivers/input/Makefile
> index 5ca3f63..b4f11f5 100644
> --- a/drivers/input/Makefile
> +++ b/drivers/input/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_INPUT)		+= input-core.o
>  input-core-y := input.o input-compat.o input-mt.o ff-core.o
>  
>  obj-$(CONFIG_INPUT_FF_MEMLESS)	+= ff-memless.o
> +obj-$(CONFIG_INPUT_FF_MEMLESS_NEXT)	+= ff-memless-next.o
>  obj-$(CONFIG_INPUT_POLLDEV)	+= input-polldev.o
>  obj-$(CONFIG_INPUT_SPARSEKMAP)	+= sparse-keymap.o
>  obj-$(CONFIG_INPUT_MATRIXKMAP)	+= matrix-keymap.o
> diff --git a/drivers/input/ff-memless-next.c b/drivers/input/ff-memless-next.c
> new file mode 100644
> index 0000000..24619e9
> --- /dev/null
> +++ b/drivers/input/ff-memless-next.c
> @@ -0,0 +1,1037 @@
> +/*
> + * Force feedback support for memoryless devices
> + *
> + * This module is based on "ff-memless" orignally written by Anssi Hannula.
> + * It is extended to support all force feedback effects currently supported
> + * by the Linux input stack.
> + * Logic of emulation of FF_RUMBLE through FF_PERIODIC provided by
> + * Elias Vanderstuyft <elias.vds@gmail.com>
> + *
> + * Copyright(c) 2014 Michal "MadCatX" Maly <madcatxster@devoid-pointer.net>
> + *
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/spinlock.h>
> +#include <linux/jiffies.h>
> +#include <linux/fixp-arith.h>
> +#include <linux/input/ff-memless-next.h>
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Michal \"MadCatX\" Maly");
> +MODULE_DESCRIPTION("Force feedback support for memoryless force feedback devices");
> +
> +#define FF_MAX_EFFECTS 16
> +#define FF_MIN_EFFECT_LENGTH ((MSEC_PER_SEC / CONFIG_HZ) + 1)
> +#define FF_EFFECT_STARTED 1
> +#define FF_EFFECT_PLAYING 2
> +#define FF_EFFECT_EMULATED 3
> +
> +enum mlnx_emulate {
> +	EMUL_NOTHING,	/* Do not emulate anything */
> +	EMUL_RUMBLE,	/* Emulate FF_RUMBLE with FF_PERIODIC */
> +	EMUL_PERIODIC	/* Emulate FF_PERIODIC with FF_RUMBLE */
> +};
> +
> +struct mlnx_effect {
> +	struct ff_effect effect;
> +	unsigned long flags;
> +	unsigned long begin_at;
> +	unsigned long stop_at;
> +	unsigned long updated_at;
> +	unsigned long attack_stop;
> +	unsigned long fade_begin;
> +	int repeat;
> +};
> +
> +struct mlnx_device {
> +	u8 combinable_playing;
> +	u8 rumble_playing;
> +	unsigned long update_rate_jiffies;
> +	void *private;
> +	struct mlnx_effect effects[FF_MAX_EFFECTS];
> +	u16 gain;
> +	struct timer_list timer;
> +	struct input_dev *dev;
> +	enum mlnx_emulate emul;
> +
> +	int (*control_effect)(struct input_dev *, void *,
> +			      const struct mlnx_effect_command *);
> +};
> +
> +static s32 mlnx_calculate_x_force(const s32 level,
> +						  const u16 direction)
> +{
> +	s32 new = (level * -fixp_sin(direction)) >> FRAC_N;
> +	pr_debug("x force: %d\n", new);
> +	return new;
> +}
> +
> +static s32 mlnx_calculate_y_force(const s32 level,
> +						  const u16 direction)
> +{
> +	s32 new = (level * fixp_cos(direction)) >> FRAC_N;
> +	pr_debug("y force: %d\n", new);
> +	return new;
> +}
> +
> +static bool mlnx_is_combinable(const struct ff_effect *effect)
> +{
> +	switch (effect->type) {
> +	case FF_CONSTANT:
> +	case FF_PERIODIC:
> +	case FF_RAMP:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static bool mlnx_is_conditional(const struct ff_effect *effect)
> +{
> +	switch (effect->type) {
> +	case FF_DAMPER:
> +	case FF_FRICTION:
> +	case FF_INERTIA:
> +	case FF_SPRING:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static void mlnx_clr_emulated(struct mlnx_effect *mlnxeff)
> +{
> +	__clear_bit(FF_EFFECT_EMULATED, &mlnxeff->flags);
> +}
> +
> +static void mlnx_clr_playing(struct mlnx_effect *mlnxeff)
> +{
> +	__clear_bit(FF_EFFECT_PLAYING, &mlnxeff->flags);
> +}
> +
> +static void mlnx_clr_started(struct mlnx_effect *mlnxeff)
> +{
> +	__clear_bit(FF_EFFECT_STARTED, &mlnxeff->flags);
> +}
> +
> +static bool mlnx_is_emulated(const struct mlnx_effect *mlnxeff)
> +{
> +	return test_bit(FF_EFFECT_EMULATED, &mlnxeff->flags);
> +}
> +
> +static bool mlnx_is_rumble(const struct ff_effect *effect)
> +{
> +	return effect->type == FF_RUMBLE;
> +}
> +
> +static bool mlnx_is_playing(const struct mlnx_effect *mlnxeff)
> +{
> +	return test_bit(FF_EFFECT_PLAYING, &mlnxeff->flags);
> +}
> +
> +static bool mlnx_is_started(const struct mlnx_effect *mlnxeff)
> +{
> +	return test_bit(FF_EFFECT_STARTED, &mlnxeff->flags);
> +}
> +
> +static bool mlnx_test_set_playing(struct mlnx_effect *mlnxeff)
> +{
> +	return test_and_set_bit(FF_EFFECT_PLAYING, &mlnxeff->flags);
> +}
> +
> +static const struct ff_envelope *mlnx_get_envelope(const struct ff_effect *effect)
> +{
> +	static const struct ff_envelope empty;
> +
> +	switch (effect->type) {
> +	case FF_CONSTANT:
> +		return &effect->u.constant.envelope;
> +	case FF_PERIODIC:
> +		return &effect->u.periodic.envelope;
> +	case FF_RAMP:
> +		return &effect->u.ramp.envelope;
> +	default:
> +		return &empty;
> +	}
> +}
> +
> +/* Some devices might have a limit on how many uncombinable effects
> + * can be played at once */
> +static int mlnx_upload_conditional(struct mlnx_device *mlnxdev,
> +				   const struct ff_effect *effect)
> +{
> +	struct mlnx_effect_command ecmd = {
> +		.cmd = MLNX_UPLOAD_UNCOMB,
> +		.u.uncomb.id = effect->id,
> +		.u.uncomb.effect = effect
> +	};
> +	return mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private, &ecmd);
> +}
> +
> +static int mlnx_erase_conditional(struct mlnx_device *mlnxdev,
> +				  const struct ff_effect *effect)
> +{
> +	struct mlnx_effect_command ecmd = {
> +		.cmd = MLNX_ERASE_UNCOMB,
> +		.u.uncomb.id = effect->id,
> +		.u.uncomb.effect = effect
> +	};
> +	return mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private, &ecmd);
> +}
> +
> +static void mlnx_set_envelope_times(struct mlnx_effect *mlnxeff)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const struct ff_envelope *envelope = mlnx_get_envelope(effect);
> +
> +	if (envelope->attack_length) {
> +		unsigned long j = msecs_to_jiffies(envelope->attack_length);
> +		mlnxeff->attack_stop = mlnxeff->begin_at + j;
> +	}
> +	if (effect->replay.length && envelope->fade_length) {
> +		unsigned long j = msecs_to_jiffies(envelope->fade_length);
> +		mlnxeff->fade_begin = mlnxeff->stop_at - j;
> +	}
> +}
> +
> +static void mlnx_set_trip_times(struct mlnx_effect *mlnxeff,
> +				const unsigned long now)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const u16 replay_delay = effect->replay.delay;
> +	const u16 replay_length = effect->replay.length;
> +
> +	mlnxeff->begin_at = now + msecs_to_jiffies(replay_delay);
> +	mlnxeff->stop_at = mlnxeff->begin_at + msecs_to_jiffies(replay_length);
> +	mlnxeff->updated_at = mlnxeff->begin_at;
> +}
> +
> +static void mlnx_start_effect(struct mlnx_effect *mlnxeff)
> +{
> +	const unsigned long now = jiffies;
> +
> +	mlnx_set_trip_times(mlnxeff, now);
> +	mlnx_set_envelope_times(mlnxeff);
> +	__set_bit(FF_EFFECT_STARTED, &mlnxeff->flags);
> +}
> +
> +static void mlnx_stop_effect(struct mlnx_device *mlnxdev,
> +			     const struct mlnx_effect *mlnxeff)
> +{
> +	switch (mlnxeff->effect.type) {
> +	case FF_PERIODIC:
> +		if (mlnx_is_emulated(mlnxeff)) {
> +			if (--mlnxdev->rumble_playing == 0) {
> +				const struct mlnx_effect_command c = {
> +					.cmd = MLNX_STOP_RUMBLE
> +				};
> +				mlnxdev->control_effect(mlnxdev->dev,
> +							mlnxdev->private, &c);
> +			}
> +			return;
> +		}
> +	case FF_CONSTANT:
> +	case FF_RAMP:
> +		if (--mlnxdev->combinable_playing == 0) {
> +			const struct mlnx_effect_command c = {
> +				.cmd = MLNX_STOP_COMBINED
> +			};
> +			mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private,
> +						&c);
> +		}
> +		return;
> +	case FF_RUMBLE:
> +		if (mlnx_is_emulated(mlnxeff)) {
> +			if (--mlnxdev->combinable_playing == 0) {
> +				const struct mlnx_effect_command c = {
> +					.cmd = MLNX_STOP_COMBINED
> +				};
> +				mlnxdev->control_effect(mlnxdev->dev,
> +							mlnxdev->private, &c);
> +			}
> +		} else {
> +			if (--mlnxdev->rumble_playing == 0) {
> +				const struct mlnx_effect_command c = {
> +					.cmd = MLNX_STOP_RUMBLE
> +				};
> +				mlnxdev->control_effect(mlnxdev->dev,
> +							mlnxdev->private, &c);
> +			}
> +		}
> +		return;
> +	case FF_DAMPER:
> +	case FF_FRICTION:
> +	case FF_INERTIA:
> +	case FF_SPRING:
> +	{
> +		const struct mlnx_effect_command c = {
> +			.cmd = MLNX_STOP_UNCOMB,
> +			.u.uncomb.id = mlnxeff->effect.id,
> +			.u.uncomb.effect = &mlnxeff->effect
> +		};
> +		mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private, &c);
> +		return;
> +	}
> +	default:
> +		return;
> +	}
> +}
> +
> +static int mlnx_restart_effect(struct mlnx_device *mlnxdev,
> +			       struct mlnx_effect *mlnxeff)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const unsigned long now = jiffies;
> +
> +	if (mlnx_is_combinable(effect)) {
> +		if (effect->replay.delay)
> +			mlnx_stop_effect(mlnxdev, mlnxeff);
> +		else {
> +			if (mlnx_is_emulated(mlnxeff))
> +				mlnxdev->rumble_playing--;
> +			else
> +				mlnxdev->combinable_playing--;
> +		}
> +	} else if (mlnx_is_rumble(effect)) {
> +		if (effect->replay.delay)
> +			mlnx_stop_effect(mlnxdev, mlnxeff);
> +		else {
> +			if (mlnx_is_emulated(mlnxeff))
> +				mlnxdev->combinable_playing--;
> +			else
> +				mlnxdev->rumble_playing--;
> +		}
> +	} else if (mlnx_is_conditional(effect)) {
> +		int ret;
> +		if (effect->replay.delay)
> +			mlnx_stop_effect(mlnxdev, mlnxeff);
> +
> +		ret = mlnx_upload_conditional(mlnxdev, &mlnxeff->effect);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	mlnx_set_trip_times(mlnxeff, now);
> +	mlnx_set_envelope_times(mlnxeff);
> +
> +	return 0;
> +}
> +
> +static s32 mlnx_apply_envelope(const struct mlnx_effect *mlnxeff,
> +			       const s32 level)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const struct ff_envelope *envelope = mlnx_get_envelope(effect);
> +	const unsigned long now = jiffies;
> +	const s32 alevel = abs(level);
> +
> +	/* Effect has an envelope with nonzero attack time */
> +	if (envelope->attack_length && time_before(now, mlnxeff->attack_stop)) {
> +		const s32 clength = jiffies_to_msecs(now - mlnxeff->begin_at);
> +		const s32 alength = envelope->attack_length;
> +		const s32 dlevel = (alevel - envelope->attack_level)
> +				 * clength / alength;
> +		return level < 0 ? -(dlevel + envelope->attack_level) :
> +				    (dlevel + envelope->attack_level);
> +	} else if (envelope->fade_length && time_before_eq(mlnxeff->fade_begin, now)) {
> +		const s32 clength = jiffies_to_msecs(now - mlnxeff->fade_begin);
> +		const s32 flength = envelope->fade_length;
> +		const s32 dlevel = (envelope->fade_level - alevel)
> +				 * clength / flength;
> +		return level < 0 ? -(dlevel + alevel) : (dlevel + alevel);
> +	}
> +
> +	return level;
> +}
> +
> +static s32 mlnx_calculate_periodic(struct mlnx_effect *mlnxeff, const s32 level)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const unsigned long now = jiffies;
> +	const u16 period = effect->u.periodic.period;
> +	const u16 phase = effect->u.periodic.phase;
> +	const s16 offset = effect->u.periodic.offset;
> +	s32 new = level;
> +	u16 t = (jiffies_to_msecs(now - mlnxeff->begin_at) + phase) % period;
> +
> +	switch (effect->u.periodic.waveform) {
> +	case FF_SINE:
> +	{
> +		u16 degrees = (360 * t) / period;
> +		new = ((level * fixp_sin(degrees)) >> FRAC_N) + offset;
> +		break;
> +	}
> +	case FF_SQUARE:
> +	{
> +		u16 degrees = (360 * t) / period;
> +		new = level * (degrees < 180 ? 1 : -1) + offset;
> +		break;
> +	}
> +	case FF_SAW_UP:
> +		new = 2 * level * t / period - level + offset;
> +		break;
> +	case FF_SAW_DOWN:
> +		new = level - 2 * level * t / period + offset;
> +		break;
> +	case FF_TRIANGLE:
> +	{
> +		new = (2 * abs(level - (2 * level * t) / period));
> +		new = new - abs(level) + offset;
> +		break;
> +	}
> +	case FF_CUSTOM:
> +		pr_debug("Custom waveform is not handled by this driver\n");
> +		return level;
> +	default:
> +		pr_err("Invalid waveform\n");
> +		return level;
> +	}
> +
> +	/* Ensure that the offset did not make the value exceed s16 range */
> +	new = clamp(new, -0x7fff, 0x7fff);
> +	pr_debug("level: %d, t: %u\n", new, t);
> +	return new;
> +}
> +
> +static s32 mlnx_calculate_ramp(const struct mlnx_effect *mlnxeff)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const struct ff_envelope *envelope = mlnx_get_envelope(effect);
> +	const unsigned long now = jiffies;
> +	const u16 length = effect->replay.length;
> +	const s16 mean = (effect->u.ramp.start_level + effect->u.ramp.end_level) / 2;
> +	const u16 t = jiffies_to_msecs(now - mlnxeff->begin_at);
> +	s32 start = effect->u.ramp.start_level;
> +	s32 end = effect->u.ramp.end_level;
> +	s32 new;
> +
> +	if (envelope->attack_length && time_before(now, mlnxeff->attack_stop)) {
> +		const s32 clength = jiffies_to_msecs(now - mlnxeff->begin_at);
> +		const s32 alength = envelope->attack_length;
> +		s32 attack_level;
> +		if (end > start)
> +			attack_level = mean - envelope->attack_level;
> +		else
> +			attack_level = mean + envelope->attack_level;
> +		start = (start - attack_level) * clength / alength
> +		      + attack_level;
> +	} else if (envelope->fade_length && time_before_eq(mlnxeff->fade_begin, now)) {
> +		const s32 clength = jiffies_to_msecs(now - mlnxeff->fade_begin);
> +		const s32 flength = envelope->fade_length;
> +		s32 fade_level;
> +		if (end > start)
> +			fade_level = mean + envelope->fade_level;
> +		else
> +			fade_level = mean - envelope->fade_level;
> +		end = (fade_level - end) * clength / flength + end;
> +	}
> +
> +	new = ((end - start) * t) / length + start;
> +	new = clamp(new, -0x7fff, 0x7fff);
> +	pr_debug("RAMP level: %d, t: %u\n", new, t);
> +	return new;
> +}
> +
> +static void mlnx_destroy(struct ff_device *dev)
> +{
> +	struct mlnx_device *mlnxdev = dev->private;
> +	del_timer_sync(&mlnxdev->timer);
> +
> +	kfree(mlnxdev->private);
> +}
> +
> +static unsigned long mlnx_get_envelope_update_time(const struct mlnx_effect *mlnxeff,
> +						   const unsigned long update_rate_jiffies)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const struct ff_envelope *envelope = mlnx_get_envelope(effect);
> +	const unsigned long now = jiffies;
> +	unsigned long fade_next;
> +
> +	/* Effect has an envelope with nonzero attack time */
> +	if (envelope->attack_length && time_before(now, mlnxeff->attack_stop)) {
> +		if (time_before(mlnxeff->updated_at + update_rate_jiffies, mlnxeff->attack_stop))
> +			return mlnxeff->updated_at + update_rate_jiffies;
> +
> +		return mlnxeff->attack_stop;
> +	}
> +
> +	/* Effect has an envelope with nonzero fade time */
> +	if (mlnxeff->effect.replay.length) {
> +		if (!envelope->fade_length)
> +			return mlnxeff->stop_at;
> +
> +		/* Schedule the next update when the fade begins */
> +		if (time_before(mlnxeff->updated_at, mlnxeff->fade_begin))
> +			return mlnxeff->fade_begin;
> +
> +		/* Already fading */
> +		fade_next = mlnxeff->updated_at + update_rate_jiffies;
> +
> +		/* Schedule update when the effect stops */
> +		if (time_after(fade_next, mlnxeff->stop_at))
> +			return mlnxeff->stop_at;
> +		/* Schedule update at the next checkpoint */
> +			return fade_next;
> +	}
> +
> +	/* There is no envelope */
> +
> +	/* Prevent the effect from being started twice */
> +	if (mlnxeff->begin_at == now && mlnx_is_playing(mlnxeff))
> +		return now - 1;
> +
> +	return mlnxeff->begin_at;
> +}
> +
> +static unsigned long mlnx_get_update_time(struct mlnx_effect *mlnxeff,
> +				const unsigned long update_rate_jiffies)
> +{
> +	const unsigned long now = jiffies;
> +	unsigned long time, update_periodic;
> +
> +	switch (mlnxeff->effect.type) {
> +	/* Constant effect does not change with time, but it can have
> +	 * an envelope and a duration */
> +	case FF_CONSTANT:
> +		return mlnx_get_envelope_update_time(mlnxeff,
> +						     update_rate_jiffies);
> +	/* Periodic and ramp effects have to be periodically updated */
> +	case FF_PERIODIC:
> +	case FF_RAMP:
> +		time = mlnx_get_envelope_update_time(mlnxeff,
> +						     update_rate_jiffies);
> +		if (mlnx_is_emulated(mlnxeff))
> +			update_periodic = mlnxeff->stop_at;
> +		else
> +			update_periodic = mlnxeff->updated_at +
> +					  update_rate_jiffies;
> +
> +		/* Periodic effect has to be updated earlier than envelope
> +		 * or envelope update time is in the past */
> +		if (time_before(update_periodic, time) || time_before(time, now))
> +			return update_periodic;
> +		/* Envelope needs to be updated */
> +		return time;
> +	case FF_RUMBLE:
> +		if (mlnx_is_emulated(mlnxeff))
> +			return mlnxeff->updated_at + update_rate_jiffies;
> +	case FF_DAMPER:
> +	case FF_FRICTION:
> +	case FF_INERTIA:
> +	case FF_SPRING:
> +	default:
> +		if (time_after_eq(mlnxeff->begin_at, now))
> +			return mlnxeff->begin_at;
> +
> +		return mlnxeff->stop_at;
> +	}
> +}
> +
> +static void mlnx_schedule_playback(struct mlnx_device *mlnxdev)
> +{
> +	struct mlnx_effect *mlnxeff;
> +	const unsigned long now = jiffies;
> +	int events = 0;
> +	int i;
> +	unsigned long earliest = 0;
> +	unsigned long time;
> +
> +	/* Iterate over all effects and determine the earliest
> +	 * time when we have to attend to any */
> +	for (i = 0; i < FF_MAX_EFFECTS; i++) {
> +		mlnxeff = &mlnxdev->effects[i];
> +
> +		if (!mlnx_is_started(mlnxeff))
> +			continue; /* Effect is not started, skip it */
> +
> +		if (mlnx_is_playing(mlnxeff))
> +			time = mlnx_get_update_time(mlnxeff,
> +						mlnxdev->update_rate_jiffies);
> +		else
> +			time = mlnxeff->begin_at;
> +
> +		pr_debug("Update time for effect %d: %lu\n", i, time);
> +
> +		/* Scheduled time is in the future and is either
> +		 * before the current earliest time or it is
> +		 * the first valid time value in this pass */
> +		if (time_before_eq(now, time) &&
> +		    (++events == 1 || time_before(time, earliest)))
> +			earliest = time;
> +	}
> +
> +	if (events) {
> +		pr_debug("Events: %d, earliest: %lu\n", events, earliest);
> +		mod_timer(&mlnxdev->timer, earliest);
> +	} else {
> +		pr_debug("No events, deactivating timer\n");
> +		del_timer(&mlnxdev->timer);
> +	}
> +}
> +
> +static u16 mlnx_calculate_rumble_direction(const u32 total_mag, const u16 total_dir,
> +					   const u32 new_mag, const u16 new_dir)
> +{
> +	if (!new_mag)
> +		return total_dir;
> +	if (!total_mag)
> +		return new_dir;
> +	return (((total_dir >> 1) * total_mag +
> +		(new_dir >> 1) * new_mag) /
> +		(total_mag + new_mag)) << 1;
> +}
> +
> +static void mlnx_add_force(struct mlnx_effect *mlnxeff, s32 *cfx, s32 *cfy,
> +			   const u16 gain)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	u16 direction;
> +	s32 level;
> +
> +	pr_debug("Processing effect type %d, ID %d\n",
> +		 mlnxeff->effect.type, mlnxeff->effect.id);
> +
> +	direction = mlnxeff->effect.direction * 360 / 0xffff;
> +	pr_debug("Direction deg: %u\n", direction);
> +
> +	switch (mlnxeff->effect.type) {
> +	case FF_CONSTANT:
> +		level = mlnx_apply_envelope(mlnxeff, effect->u.constant.level);
> +		break;
> +	case FF_PERIODIC:
> +		level = mlnx_apply_envelope(mlnxeff,
> +					    effect->u.periodic.magnitude);
> +		level = mlnx_calculate_periodic(mlnxeff, level);
> +		break;
> +	case FF_RAMP:
> +		level = mlnx_calculate_ramp(mlnxeff);
> +		break;
> +	default:
> +		pr_err("Effect %d not handled by mlnx_add_force\n",
> +		       mlnxeff->effect.type);
> +		return;
> +	}
> +
> +	*cfx += mlnx_calculate_x_force(level, direction) * gain / 0xffff;
> +	*cfy += mlnx_calculate_y_force(level, direction) * gain / 0xffff;
> +}
> +
> +static void mlnx_add_rumble(const struct mlnx_effect *mlnxeff, u32 *strong_mag,
> +			    u32 *weak_mag, u16 *strong_dir,
> +			    u16 *weak_dir, const u16 gain)
> +{
> +	const struct ff_effect *eff = &mlnxeff->effect;
> +	const struct ff_rumble_effect *reff = &mlnxeff->effect.u.rumble;
> +	const u32 new_strong_mag = (u32)reff->strong_magnitude * gain / 0xffffU;
> +	const u32 new_weak_mag = (u32)reff->weak_magnitude * gain / 0xffffU;
> +
> +	*strong_dir = mlnx_calculate_rumble_direction(*strong_mag, *strong_dir,
> +						      new_strong_mag,
> +						      eff->direction);
> +	*weak_dir = mlnx_calculate_rumble_direction(*weak_mag, *weak_dir,
> +						    new_weak_mag,
> +						    eff->direction);
> +	*strong_mag += new_strong_mag;
> +	*weak_mag += new_weak_mag;
> +}
> +
> +static void mlnx_add_emul_periodic(const struct mlnx_effect *mlnxeff,
> +				   u32 *strong_mag, u32 *weak_mag,
> +				   u16 *strong_dir, u16 *weak_dir,
> +				   const u16 gain)
> +{
> +	const struct ff_effect *eff = &mlnxeff->effect;
> +	const u32 level = (u32)abs(mlnx_apply_envelope(mlnxeff,
> +						  eff->u.periodic.magnitude)) * gain / 0x7fffU;
> +
> +	*strong_dir = mlnx_calculate_rumble_direction(*strong_mag, *strong_dir,
> +						      level, eff->direction);
> +	*weak_dir = mlnx_calculate_rumble_direction(*weak_mag, *weak_dir,
> +						    level, eff->direction);
> +
> +	*strong_mag += level;
> +	*weak_mag += level;
> +}
> +
> +static void mlnx_add_emul_rumble(const struct mlnx_effect *mlnxeff, s32 *cfx,
> +				 s32 *cfy, const u16 gain,
> +				 const unsigned long now,
> +				 const unsigned long update_rate_jiffies)
> +{
> +	const struct ff_effect *effect = &mlnxeff->effect;
> +	const u16 strong = effect->u.rumble.strong_magnitude;
> +	const u16 weak = effect->u.rumble.weak_magnitude;
> +	/* To calculate 't', we pretend that mlnxeff->begin_at == 0, thus t == now.  */
> +	/* This will synchronise all simultaneously playing emul rumble effects,     */
> +	/* otherwise non-deterministic phase-inversions could occur depending on     */
> +	/* upload time, which could lead to undesired cancellation of these effects. */
> +	const unsigned long t = now % (4UL * update_rate_jiffies);
> +	s32 level = 0;
> +	bool direction_up;
> +	bool direction_left;
> +
> +	if (strong)
> +		level += (strong / 4) * (t < 2UL * update_rate_jiffies ? 1 : -1);
> +	if (weak)
> +		level += (weak / 4) * (t < 2UL * update_rate_jiffies ?
> +					(t < 1UL * update_rate_jiffies ? 1 : -1) :
> +					(t < 3UL * update_rate_jiffies ? 1 : -1));
> +	direction_up = (effect->direction > 0x3fffU && effect->direction <= 0xbfffU);
> +	direction_left = (effect->direction <= 0x7fffU);
> +
> +	pr_debug("Emulated cf: %d, t: %lu, n: %lu, begin: %lu, diff: %lu j: %lu\n",
> +		 level, t, now, mlnxeff->begin_at, now - mlnxeff->begin_at,
> +		 update_rate_jiffies);
> +	level = (level * gain) / 0xffff;
> +	*cfx += direction_left ? -level : level;
> +	*cfy += direction_up ? -level : level;
> +}
> +
> +static void mlnx_play_effects(struct mlnx_device *mlnxdev)
> +{
> +	const u16 gain = mlnxdev->gain;
> +	const unsigned long now = jiffies;
> +	int i;
> +	s32 cfx = 0;
> +	s32 cfy = 0;
> +	u32 strong_mag = 0;
> +	u32 weak_mag = 0;
> +	u16 strong_dir = 0;
> +	u16 weak_dir = 0;
> +
> +	for (i = 0; i < FF_MAX_EFFECTS; i++) {
> +		struct mlnx_effect *mlnxeff = &mlnxdev->effects[i];
> +
> +		if (!mlnx_is_started(mlnxeff)) {
> +			pr_debug("Effect %hd/%d not started\n",
> +				 mlnxeff->effect.id, i);
> +			continue;
> +		}
> +
> +		if (time_before(now, mlnxeff->begin_at)) {
> +			pr_debug("Effect %hd/%d begins at a later time\n",
> +				 mlnxeff->effect.id, i);
> +			continue;
> +		}
> +
> +		if (time_before_eq(mlnxeff->stop_at, now) && mlnxeff->effect.replay.length) {
> +			pr_debug("Effect %hd/%d has to be stopped\n",
> +				 mlnxeff->effect.id, i);
> +
> +			mlnx_clr_playing(mlnxeff);
> +			if (--mlnxeff->repeat > 0)
> +				mlnx_restart_effect(mlnxdev, mlnxeff);
> +			else {
> +				mlnx_stop_effect(mlnxdev, mlnxeff);
> +				mlnx_clr_started(mlnxeff);
> +				mlnx_clr_emulated(mlnxeff);
> +				if (mlnx_is_conditional(&mlnxeff->effect))
> +					mlnx_erase_conditional(mlnxdev, &mlnxeff->effect);
> +			}
> +
> +			continue;
> +		}
> +
> +		switch (mlnxeff->effect.type) {
> +		case FF_PERIODIC:
> +			if (mlnxdev->emul == EMUL_PERIODIC) {
> +				if (!mlnx_test_set_playing(mlnxeff)) {
> +					mlnxdev->rumble_playing++;
> +					pr_debug("Starting emul periodic, total rumble %u\n",
> +						 mlnxdev->rumble_playing);
> +				}
> +				__set_bit(FF_EFFECT_EMULATED, &mlnxeff->flags);
> +				mlnx_add_emul_periodic(mlnxeff, &strong_mag, &weak_mag,
> +						       &strong_dir, &weak_dir, gain);
> +				break;
> +			}
> +		case FF_CONSTANT:
> +		case FF_RAMP:
> +			if (!mlnx_test_set_playing(mlnxeff)) {
> +				mlnxdev->combinable_playing++;
> +				pr_debug("Starting combinable effect, total %u\n",
> +					 mlnxdev->combinable_playing);
> +			}
> +			mlnx_add_force(mlnxeff, &cfx, &cfy, gain);
> +			break;
> +		case FF_RUMBLE:
> +			if (mlnxdev->emul == EMUL_RUMBLE) {
> +				if (!mlnx_test_set_playing(mlnxeff)) {
> +					mlnxdev->combinable_playing++;
> +					pr_debug("Starting emul rumble, total comb %u\n",
> +						 mlnxdev->combinable_playing);
> +				}
> +				__set_bit(FF_EFFECT_EMULATED, &mlnxeff->flags);
> +				mlnx_add_emul_rumble(mlnxeff, &cfx, &cfy, gain, now,
> +						     mlnxdev->update_rate_jiffies);
> +			} else {
> +				if (!mlnx_test_set_playing(mlnxeff)) {
> +					mlnxdev->rumble_playing++;
> +					pr_debug("Starting rumble effect, total %u\n",
> +						 mlnxdev->rumble_playing);
> +				}
> +				mlnx_add_rumble(mlnxeff, &strong_mag, &weak_mag,
> +						&strong_dir, &weak_dir, gain);
> +			}
> +			break;
> +		case FF_DAMPER:
> +		case FF_FRICTION:
> +		case FF_INERTIA:
> +		case FF_SPRING:
> +			if (!mlnx_test_set_playing(mlnxeff)) {
> +				const struct mlnx_effect_command ecmd = {
> +					.cmd = MLNX_START_UNCOMB,
> +					.u.uncomb.id = i,
> +					.u.uncomb.effect = &mlnxeff->effect
> +				};
> +				mlnxdev->control_effect(mlnxdev->dev,
> +						      mlnxdev->private, &ecmd);
> +			}
> +			break;
> +		default:
> +			pr_debug("Unhandled type of effect\n");
> +		}
> +		mlnxeff->updated_at = now;
> +	}
> +
> +	if (mlnxdev->combinable_playing) {
> +		const struct mlnx_effect_command ecmd = {
> +			.cmd = MLNX_START_COMBINED,
> +			.u.simple_force = {
> +				.x = clamp(cfx, -0x7fff, 0x7fff),
> +				.y = clamp(cfy, -0x7fff, 0x7fff)
> +			}
> +		};
> +		mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private, &ecmd);
> +	}
> +	if (mlnxdev->rumble_playing) {
> +		const struct mlnx_effect_command ecmd = {
> +			.cmd = MLNX_START_RUMBLE,
> +			.u.rumble_force = {
> +				.strong = clamp(strong_mag, (u32)0, (u32)0xffffU),
> +				.weak = clamp(weak_mag, (u32)0, (u32)0xffffU),
> +				.strong_dir = clamp(strong_dir, (u16)0, (u16)0xffffU),
> +				.weak_dir = clamp(weak_dir, (u16)0, (u16)0xffffU)
> +			}
> +		};
> +		mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private, &ecmd);
> +	}
> +
> +	mlnx_schedule_playback(mlnxdev);
> +}
> +
> +static void mlnx_set_gain(struct input_dev *dev, u16 gain)
> +{
> +	struct mlnx_device *mlnxdev = dev->ff->private;
> +	int i;
> +
> +	mlnxdev->gain = gain;
> +
> +	for (i = 0; i < FF_MAX_EFFECTS; i++) {
> +		struct mlnx_effect *eff = &mlnxdev->effects[i];
> +		if (eff == NULL)
> +			continue;
> +		if (mlnx_is_playing(eff)) {
> +			if (mlnx_is_combinable(&eff->effect)) {
> +				mlnx_clr_playing(eff);
> +				if (mlnx_is_emulated(eff))
> +					--mlnxdev->rumble_playing;
> +				else
> +					--mlnxdev->combinable_playing;
> +			} else if (mlnx_is_rumble(&eff->effect)) {
> +				mlnx_clr_playing(eff);
> +				if (mlnx_is_emulated(eff))
> +					--mlnxdev->combinable_playing;
> +				else
> +					--mlnxdev->rumble_playing;
> +			}
> +		}
> +	}
> +
> +	mlnx_play_effects(mlnxdev);
> +}
> +
> +static int mlnx_startstop(struct input_dev *dev, int effect_id, int repeat)
> +{
> +	struct mlnx_device *mlnxdev = dev->ff->private;
> +	struct mlnx_effect *mlnxeff = &mlnxdev->effects[effect_id];
> +	int ret;
> +
> +	if (repeat > 0) {
> +		pr_debug("Starting effect ID %d\n", effect_id);
> +		mlnxeff->repeat = repeat;
> +
> +		if (!mlnx_is_started(mlnxeff)) {
> +			/* Check that device has a free effect slot */
> +			if (mlnx_is_conditional(&mlnxeff->effect)) {
> +				ret = mlnx_upload_conditional(mlnxdev, &mlnxeff->effect);
> +				if (ret) {
> +					/* Device effect slots are all occupied */
> +					pr_debug("No free effect slot for EID %d\n", effect_id);
> +					return ret;
> +				}
> +			}
> +			mlnx_start_effect(mlnxeff);
> +		}
> +	} else {
> +		pr_debug("Stopping effect ID %d\n", effect_id);
> +		if (mlnx_is_started(mlnxeff)) {
> +			if (mlnx_is_playing(mlnxeff)) {
> +				mlnx_clr_playing(mlnxeff);
> +				mlnx_stop_effect(mlnxdev, mlnxeff);
> +			}
> +			mlnx_clr_started(mlnxeff);
> +			mlnx_clr_emulated(mlnxeff);
> +
> +			if (mlnx_is_conditional(&mlnxeff->effect))
> +				return mlnx_erase_conditional(mlnxdev, &mlnxeff->effect);
> +		} else {
> +			pr_debug("Effect ID %d already stopped\n", effect_id);
> +			return 0;
> +		}
> +	}
> +	mlnx_play_effects(mlnxdev);
> +
> +	return 0;
> +}
> +
> +static void mlnx_timer_fired(unsigned long data)
> +{
> +	struct input_dev *dev = (struct input_dev *)data;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->event_lock, flags);
> +	mlnx_play_effects(dev->ff->private);
> +	spin_unlock_irqrestore(&dev->event_lock, flags);
> +}
> +
> +static int mlnx_upload(struct input_dev *dev, struct ff_effect *effect,
> +		       struct ff_effect *old)
> +{
> +	struct mlnx_device *mlnxdev = dev->ff->private;
> +	struct mlnx_effect *mlnxeff = &mlnxdev->effects[effect->id];
> +	const u16 length = effect->replay.length;
> +	const u16 delay = effect->replay.delay;
> +	int ret, fade_from;
> +
> +	/* Effect's timing is below kernel timer resolution */
> +	if (length && length < FF_MIN_EFFECT_LENGTH)
> +		effect->replay.length = FF_MIN_EFFECT_LENGTH;
> +	if (delay && delay < FF_MIN_EFFECT_LENGTH)
> +		effect->replay.delay = FF_MIN_EFFECT_LENGTH;
> +
> +	/* Periodic effects must have a non-zero period */
> +	if (effect->type == FF_PERIODIC) {
> +		if (!effect->u.periodic.period)
> +			return -EINVAL;
> +	}
> +	/* Ramp effects cannot be infinite */
> +	if (effect->type == FF_RAMP && !length)
> +		return -EINVAL;
> +
> +	if (mlnx_is_combinable(effect)) {
> +		const struct ff_envelope *envelope = mlnx_get_envelope(effect);
> +
> +		/* Infinite effects cannot fade */
> +		if (!length && envelope->fade_length > 0)
> +			return -EINVAL;
> +		/* Fade length cannot be greater than effect duration */
> +		fade_from = (int)length - (int)envelope->fade_length;
> +		if (fade_from < 0)
> +			return -EINVAL;
> +		/* Envelope cannot start fading before it finishes attacking */
> +		if (fade_from < envelope->attack_length && fade_from > 0)
> +			return -EINVAL;
> +	}
> +
> +
> +	spin_lock_irq(&dev->event_lock);
> +	mlnxeff->effect = *effect; /* Keep internal copy of the effect */
> +	/* Check if the effect being modified is playing */
> +	if (mlnx_is_started(mlnxeff)) {
> +		if (mlnx_is_playing(mlnxeff)) {
> +			mlnx_clr_playing(mlnxeff);
> +			ret = mlnx_restart_effect(mlnxdev, mlnxeff);
> +
> +			if (ret) {
> +				/* Restore the original effect */
> +				if (old)
> +					mlnxeff->effect = *old;
> +				spin_unlock_irq(&dev->event_lock);
> +				return ret;
> +			}
> +		}
> +
> +		mlnx_schedule_playback(mlnxdev);
> +	}
> +
> +	spin_unlock_irq(&dev->event_lock);
> +
> +	return 0;
> +}
> +
> +int input_ff_create_mlnx(struct input_dev *dev, void *data,
> +			 int (*control_effect)(struct input_dev *, void *, const struct mlnx_effect_command *),
> +			 const u16 update_rate)
> +{
> +	struct mlnx_device *mlnxdev;
> +	int ret;
> +	const u16 min_update_rate = update_rate < FF_MIN_EFFECT_LENGTH ?
> +				    FF_MIN_EFFECT_LENGTH : update_rate;
> +
> +	mlnxdev = kzalloc(sizeof(*mlnxdev), GFP_KERNEL);
> +	if (!mlnxdev)
> +		return -ENOMEM;
> +
> +	mlnxdev->dev = dev;
> +	mlnxdev->private = data;
> +	mlnxdev->control_effect = control_effect;
> +	mlnxdev->gain = 0xffff;
> +	mlnxdev->update_rate_jiffies = msecs_to_jiffies(min_update_rate);
> +	input_set_capability(dev, EV_FF, FF_GAIN);
> +	setup_timer(&mlnxdev->timer, mlnx_timer_fired, (unsigned long)dev);
> +
> +	/* Set up effect emulation if needed */
> +	if (test_bit(FF_PERIODIC, dev->ffbit) &&
> +	    !test_bit(FF_RUMBLE, dev->ffbit)) {
> +		set_bit(FF_RUMBLE, dev->ffbit);
> +		mlnxdev->emul = EMUL_RUMBLE;
> +		pr_debug("Emulating RUMBLE with PERIODIC\n");
> +	} else if (test_bit(FF_RUMBLE, dev->ffbit) &&
> +		   !test_bit(FF_PERIODIC, dev->ffbit)) {
> +		set_bit(FF_PERIODIC, dev->ffbit);
> +		set_bit(FF_SINE, dev->ffbit);
> +		set_bit(FF_SQUARE, dev->ffbit);
> +		set_bit(FF_TRIANGLE, dev->ffbit);
> +		set_bit(FF_SAW_DOWN, dev->ffbit);
> +		set_bit(FF_SAW_UP, dev->ffbit);
> +		mlnxdev->emul = EMUL_PERIODIC;
> +		pr_debug("Emulating PERIODIC with RUMBLE\n");
> +	} else {
> +		mlnxdev->emul = EMUL_NOTHING;
> +		pr_debug("No effect emulation is necessary\n");
> +	}
> +
> +	ret = input_ff_create(dev, FF_MAX_EFFECTS);
> +	if (ret) {
> +		kfree(mlnxdev);
> +		return ret;
> +	}
> +
> +
> +	dev->ff->private = mlnxdev;
> +	dev->ff->upload = mlnx_upload;
> +	dev->ff->set_gain = mlnx_set_gain;
> +	dev->ff->destroy = mlnx_destroy;
> +	dev->ff->playback = mlnx_startstop;
> +
> +	pr_debug("Device successfully registered.\n");
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(input_ff_create_mlnx);
> diff --git a/include/linux/input/ff-memless-next.h b/include/linux/input/ff-memless-next.h
> new file mode 100644
> index 0000000..7522451
> --- /dev/null
> +++ b/include/linux/input/ff-memless-next.h
> @@ -0,0 +1,162 @@
> +#include <linux/input.h>
> +
> +/** DEFINITION OF TERMS
> + *
> + * Combined effect - An effect whose force is a superposition of forces
> + *                   generated by all effects that can be added together.
> + *                   Only one combined effect can be playing at a time.
> + *                   Effects that can be added together to create a combined
> + *                   effect are FF_CONSTANT, FF_PERIODIC and FF_RAMP.
> + * Uncombinable effect - An effect that cannot be combined with another effect.
> + *                       All conditional effects - FF_DAMPER, FF_FRICTION,
> + *                       FF_INERTIA and FF_SPRING are uncombinable.
> + *                       Number of uncombinable effects playing simultaneously
> + *                       depends on the capabilities of the hardware.
> + * Rumble effect - An effect generated by device's rumble motors instead of
> + *                 force feedback actuators.
> + *
> + *
> + * HANDLING OF UNCOMBINABLE EFFECTS
> + *
> + * Uncombinable effects cannot be combined together into just one effect, at
> + * least not in a clear and obvious manner. Therefore these effects have to
> + * be handled individually by ff-memless-next. Handling of these effects is
> + * left entirely to the hardware-specific driver, ff-memless-next merely
> + * passes these effects to the hardware-specific driver at appropriate time.
> + * ff-memless-next provides the UPLOAD command to notify the hardware-specific
> + * driver that the userspace is about to request playback of an uncombinable
> + * effect. The hardware-specific driver shall take all steps needed to make
> + * the device ready to play the effect when it receives the UPLOAD command.
> + * The actual playback shall commence when START_UNCOMB command is received.
> + * Opposite to the UPLOAD command is the ERASE command which tells
> + * the hardware-specific driver that the playback has finished and that
> + * the effect will not be restarted. STOP_UNCOMB command tells
> + * the hardware-specific driver that the playback shall stop but the device
> + * shall still be ready to resume the playback immediately.
> + *
> + * In case it is not possible to make the device ready to play an uncombinable
> + * effect (all hardware effect slots are occupied), the hardware-specific
> + * driver may return an error when it receives an UPLOAD command. If the
> + * hardware-specific driver returns 0, the upload is considered successful.
> + * START_UNCOMB and STOP_UNCOMB commands cannot fail and the device must always
> + * start the playback of the requested effect if the UPLOAD command of the
> + * respective effect has been successful. ff-memless-next will never send
> + * a START/STOP_UNCOMB command for an effect that has not been uploaded
> + * successfully, nor will it send an ERASE command for an effect that is
> + * playing (= has been started with START_UNCOMB command).
> + */
> +
> +enum mlnx_commands {
> +	/* Start or update a combined effect. This command is sent whenever
> +	 * a FF_CONSTANT, FF_PERIODIC or FF_RAMP is started, stopped or
> +	 * updated by userspace, when the applied envelopes are recalculated
> +	 * or when periodic effects are recalculated. */
> +	MLNX_START_COMBINED,
> +	/* Stop combined effect. This command is sent when all combinable
> +	 * effects are stopped. */
> +	MLNX_STOP_COMBINED,
> +	/* Start or update a rumble effect. This command is sent whenever
> +	 * a FF_RUMBLE effect is started or when its magnitudes or directions
> +	 * change. */
> +	MLNX_START_RUMBLE,
> +	/* Stop a rumble effect. This command is sent when all FF_RUMBLE
> +	 * effects are stopped. */
> +	MLNX_STOP_RUMBLE,
> +	/* Start or update an uncombinable effect. This command is sent
> +	 * whenever an uncombinable effect is started or updated. */
> +	MLNX_START_UNCOMB,
> +	/* Stop uncombinable effect. This command is sent when an uncombinable
> +	 * effect is stopped. */
> +	MLNX_STOP_UNCOMB,
> +	/* Upload uncombinable effect to device. This command is sent when the
> +	 * effect is started from userspace. It is up to the hardware-specific
> +	 * driver to handle this situation.
> +	 */
> +	MLNX_UPLOAD_UNCOMB,
> +	/* Remove uncombinable effect from device, This command is sent when
> +	 * and uncombinable effect has finished playing and will not be
> +	 * restarted.
> +	 */
> +	MLNX_ERASE_UNCOMB
> +};
> +
> +/** struct mlnx_simple_force - holds constant forces along X and Y axis
> + * @x: Force along X axis. Negative value denotes force pulling to the left,
> + *     positive value denotes force pulling to the right.
> + * @y: Force along Y axis. Negative value denotes force denotes force pulling
> + *     away from the user, positive value denotes force pulling towards
> + *     the user.
> + */
> +struct mlnx_simple_force {
> +	const s32 x;
> +	const s32 y;
> +};
> +
> +/** struct mlnx_rumble_force - holds information about rumble effect
> + * @strong: Magnitude of the strong vibration.
> + * @weak: Magnitude of the weak vibration.
> + * @strong_dir: Direction of the strong vibration expressed in the same way
> + *              as the direction of force feedback effect in struct ff_effect.
> + * @weak_dir: Direction of the weak vibration, same as above applies.
> + */
> +struct mlnx_rumble_force {
> +	const u32 strong;
> +	const u32 weak;
> +	const u16 strong_dir;
> +	const u16 weak_dir;
> +};
> +
> +/** struct mlnx_uncomb_effect - holds information about uncombinable effect
> + * @id: Id of the effect assigned by ff-core.
> + * @effect: Pointer to the uncombinable effect stored in ff-memless-next module
> + *          Hardware-specific driver must not alter this.
> + */
> +struct mlnx_uncomb_effect {
> +	const int id;
> +	const struct ff_effect *effect;
> +};
> +
> +/** struct mlnx_commands - describes what action shall the force feedback
> + *                         device perform
> + * @cmd: Type of the action.
> + * @u: Data associated with the action.
> + */
> +struct mlnx_effect_command {
> +	const enum mlnx_commands cmd;
> +	union {
> +		const struct mlnx_simple_force simple_force;
> +		const struct mlnx_rumble_force rumble_force;
> +		const struct mlnx_uncomb_effect uncomb;
> +	} u;
> +};
> +
> +/** input_ff_create_mlnx() - Register a device within ff-memless-next and
> + *                           the kernel force feedback system
> + * @dev: Pointer to the struct input_dev associated with the device.
> + * @data: Any device-specific data that shall be passed to the callback.
> + *        function called by ff-memless-next when a force feedback action
> + *        shall be performed.
> + * @control_effect: Pointer to the callback function.
> + * @update_date: Delay in milliseconds between two recalculations of periodic
> + *               effects, ramp effects and envelopes. Note that this value will
> + *               never be lower than (CONFIG_HZ / 1000) + 1 regardless of the
> + *               value specified here. This is not a "hard" rate limiter.
> + *               Userspace still can submit effects at a rate faster than
> + *               this value.
> + */
> +int input_ff_create_mlnx(struct input_dev *dev, void *data,
> +			 int (*control_effect)(struct input_dev *, void *, const struct mlnx_effect_command *),
> +			 const u16 update_rate);
> +
> +/** int control_effect() - Callback to the HW-specific driver.
> + * @struct input_dev *: Pointer to the struct input_dev of the device that is
> + *                     is being controlled.
> + * @void *: Pointer to any device-specific data set by the HW-specific driver.
> + *         This data will be free'd automatically by ff-memless-next when the
> + *         device is destroyed.
> + * @const struct mlnx_effect_command *:
> + *         Action the device shall perform. Note that this pointer is valid
> + *         only within the context of the callback function. If the HW-specific
> + *         driver needs any data from this structure after the callback
> + *         function returns, it must copy it.
> + */
> -- 
> 1.9.2
> 
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-- 
Antonio Ospite
http://ao2.it

A: Because it messes up the order in which people normally read text.
   See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?
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