drivers/input/ff-memless.c



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/*
 *  Force feedback support for memoryless devices
 *
 *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
 *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
 */

/*
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/* #define DEBUG */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/jiffies.h>

#include "fixp-arith.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
MODULE_DESCRIPTION("Force feedback support for memoryless devices");

/* Number of effects handled with memoryless devices */
#define FF_MEMLESS_EFFECTS	16

/* Envelope update interval in ms */
#define FF_ENVELOPE_INTERVAL	50

#define FF_EFFECT_STARTED	0
#define FF_EFFECT_PLAYING	1
#define FF_EFFECT_ABORTING	2

struct ml_effect_state {
	struct ff_effect *effect;
	unsigned long flags;	/* effect state (STARTED, PLAYING, etc) */
	int count;		/* loop count of the effect */
	unsigned long play_at;	/* start time */
	unsigned long stop_at;	/* stop time */
	unsigned long adj_at;	/* last time the effect was sent */
};

struct ml_device {
	void *private;
	struct ml_effect_state states[FF_MEMLESS_EFFECTS];
	int gain;
	struct timer_list timer;
	struct input_dev *dev;

	int (*play_effect)(struct input_dev *dev, void *data,
			   struct ff_effect *effect);
};

static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
{
	static const struct ff_envelope empty_envelope;

	switch (effect->type) {
		case FF_PERIODIC:
			return &effect->u.periodic.envelope;
		case FF_CONSTANT:
			return &effect->u.constant.envelope;
		default:
			return &empty_envelope;
	}
}

/*
 * Check for the next time envelope requires an update on memoryless devices
 */
static unsigned long calculate_next_time(struct ml_effect_state *state)
{
	const struct ff_envelope *envelope = get_envelope(state->effect);
	unsigned long attack_stop, fade_start, next_fade;

	if (envelope->attack_length) {
		attack_stop = state->play_at +
			msecs_to_jiffies(envelope->attack_length);
		if (time_before(state->adj_at, attack_stop))
			return state->adj_at +
					msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
	}

	if (state->effect->replay.length) {
		if (envelope->fade_length) {
			/* check when fading should start */
			fade_start = state->stop_at -
					msecs_to_jiffies(envelope->fade_length);

			if (time_before(state->adj_at, fade_start))
				return fade_start;

			/* already fading, advance to next checkpoint */
			next_fade = state->adj_at +
					msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
			if (time_before(next_fade, state->stop_at))
				return next_fade;
		}

		return state->stop_at;
	}

	return state->play_at;
}

static void ml_schedule_timer(struct ml_device *ml)
{
	struct ml_effect_state *state;
	unsigned long now = jiffies;
	unsigned long earliest = 0;
	unsigned long next_at;
	int events = 0;
	int i;

	pr_debug("calculating next timer\n");

	for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {

		state = &ml->states[i];

		if (!test_bit(FF_EFFECT_STARTED, &state->flags))
			continue;

		if (test_bit(FF_EFFECT_PLAYING, &state->flags))
			next_at = calculate_next_time(state);
		else
			next_at = state->play_at;

		if (time_before_eq(now, next_at) &&
		    (++events == 1 || time_before(next_at, earliest)))
			earliest = next_at;
	}

	if (!events) {
		pr_debug("no actions\n");
		del_timer(&ml->timer);
	} else {
		pr_debug("timer set\n");
		mod_timer(&ml->timer, earliest);
	}
}

/*
 * Apply an envelope to a value
 */
static int apply_envelope(struct ml_effect_state *state, int value,
			  struct ff_envelope *envelope)
{
	struct ff_effect *effect = state->effect;
	unsigned long now = jiffies;
	int time_from_level;
	int time_of_envelope;
	int envelope_level;
	int difference;

	if (envelope->attack_length &&
	    time_before(now,
			state->play_at + msecs_to_jiffies(envelope->attack_length))) {
		pr_debug("value = 0x%x, attack_level = 0x%x\n",
			 value, envelope->attack_level);
		time_from_level = jiffies_to_msecs(now - state->play_at);
		time_of_envelope = envelope->attack_length;
		envelope_level = min_t(__s16, envelope->attack_level, 0x7fff);

	} else if (envelope->fade_length && effect->replay.length &&
		   time_after(now,
			      state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
		   time_before(now, state->stop_at)) {
		time_from_level = jiffies_to_msecs(state->stop_at - now);
		time_of_envelope = envelope->fade_length;