// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Force feedback support for memoryless devices
*
* Copyright (c) 2006 Anssi Hannula <[email protected]>
* Copyright (c) 2006 Dmitry Torokhov <[email protected]>
*/
/* #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 <linux/fixp-arith.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anssi Hannula <[email protected]>");
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(u16, 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;
envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
} else
return value;
difference = abs(value) - envelope_level;
pr_debug("difference = %d\n", difference);
pr_debug("time_from_level = 0x%x\n", time_from_level);
pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
difference = difference * time_from_level / time_of_envelope;
pr_debug("difference = %d\n", difference);
return value < 0 ?
-(difference + envelope_level) : (difference + envelope_level);
}
/*
* Return the type the effect has to be converted into (memless devices)
*/
static int get_compatible_type(struct ff_device *ff, int effect_type)
{
if (test_bit(effect_type, ff->ffbit))
return effect_type;
if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
return FF_RUMBLE;
pr_err("invalid type in get_compatible_type()\n");
return 0;
}
/*
* Only left/right direction should be used (under/over 0x8000) for
* forward/reverse motor direction (to keep calculation fast & simple).
*/
static u16 ml_calculate_direction(u16 direction, u16 force,
u16 new_direction, u16 new_force)
{
if (!force)
return new_direction;
if (!new_force)
return direction;
return (((u32)(direction >> 1) * force +
(new_direction >> 1) * new_force) /
(force + new_force)) << 1;
}
#define FRAC_N 8
static inline s16 fixp_new16(s16 a)
{
return ((s32)a) >> (16 - FRAC_N);
}
static inline s16 fixp_mult(s16 a, s16 b)
{
a = ((s32)a * 0x100) / 0x7fff;
return ((s32)(a * b)) >> FRAC_N;
}
/*
* Combine two effects and apply gain.
*/
static void ml_combine_effects(struct ff_effect *effect,
struct ml_effect_state *state,
int gain)
{
struct ff_effect *new = state->effect;
unsigned int strong, weak, i;
int x, y;
s16 level;
switch (new->type) {
case FF_CONSTANT:
i = new->direction * 360 / 0xffff;
level = fixp_new16(apply_envelope(state,
new->u.constant.level,
&new->u.constant.envelope));
x = fixp_mult(fixp_sin16(i), level) * gain / 0xffff;
y = fixp_mult(-fixp_cos16(i), level) * gain / 0xffff;
/*
* here we abuse ff_ramp to hold x and y of constant force
* If in future any driver wants something else than x and y
* in s8, this should be changed to something more generic
*/
effect->u.ramp.start_level =
clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
effect->u.ramp.end_level =
clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
break;
case FF_RUMBLE:
strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
if (effect->u.rumble.strong_magnitude + strong)
effect->direction = ml_calculate_direction(
effect->direction,
effect->u.rumble.strong_magnitude,
new->direction, strong);
else if (effect->u.rumble.weak_magnitude + weak)
effect->direction = ml_calculate_direction(
effect->direction,
effect->u.rumble.weak_magnitude,
new->direction, weak);
else
effect->direction = 0;
effect->u.rumble.strong_magnitude =
min(strong + effect->u.rumble.strong_magnitude,
0xffffU);
effect->u.rumble.weak_magnitude =
min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
break;
case FF_PERIODIC:
i = apply_envelope(state, abs(new->u.periodic.magnitude),
&new->u.periodic.envelope);
/* here we also scale it 0x7fff => 0xffff */
i = i * gain / 0x7fff;
if (effect->u.rumble.strong_magnitude + i)
effect->direction = ml_calculate_direction(
effect->direction,
effect->u.rumble.strong_magnitude,
new->direction, i);
else
effect->direction = 0;
effect->u.rumble.strong_magnitude =
min(i + effect->u.rumble.strong_magnitude, 0xffffU);
effect->u.rumble.weak_magnitude =
min(i + effect->u.rumble.weak_magnitude, 0xffffU);
break;
default:
pr_err("invalid type in ml_combine_effects()\n");
break;
}
}
/*
* Because memoryless devices have only one effect per effect type active
* at one time we have to combine multiple effects into one
*/
static int ml_get_combo_effect(struct ml_device *ml,
unsigned long *effect_handled,
struct ff_effect *combo_effect)
{
struct ff_effect *effect;
struct ml_effect_state *state;
int effect_type;
int i;
memset(combo_effect, 0, sizeof(struct ff_effect));
for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
if (__test_and_set_bit(i, effect_handled))
continue;
state = &ml->states[i];
effect = state->effect;
if (!test_bit(FF_EFFECT_STARTED, &state->flags))
continue;
if (time_before(jiffies, state->play_at))
continue;
/*
* here we have started effects that are either
* currently playing (and may need be aborted)
* or need to start playing.
*/
effect_type = get_compatible_type(ml->dev->ff, effect->type);
if (combo_effect->type != effect_type) {
if (combo_effect->type != 0) {
__clear_bit(i, effect_handled);
continue;
}
combo_effect->type = effect_type;
}
if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
__clear_bit(FF_EFFECT_PLAYING, &state->flags);
__clear_bit(FF_EFFECT_STARTED, &state->flags);
} else if (effect->replay.length &&
time_after_eq(jiffies, state->stop_at)) {
__clear_bit(FF_EFFECT_PLAYING, &state->flags);
if (--state->count <= 0) {
__clear_bit(FF_EFFECT_STARTED, &state->flags);
} else {
state->play_at = jiffies +
msecs_to_jiffies(effect->replay.delay);
state->stop_at = state->play_at +
msecs_to_jiffies(effect->replay.length);
}
} else {
__set_bit(FF_EFFECT_PLAYING, &state->flags);
state->adj_at = jiffies;
ml_combine_effects(combo_effect, state, ml->gain);
}
}
return combo_effect->type != 0;
}
static void ml_play_effects(struct ml_device *ml)
{
struct ff_effect effect;
DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);
memset(handled_bm, 0, sizeof(handled_bm));
while (ml_get_combo_effect(ml, handled_bm, &effect))
ml->play_effect(ml->dev, ml->private, &effect);
ml_schedule_timer(ml);
}
static void ml_effect_timer(struct timer_list *t)
{
struct ml_device *ml = from_timer(ml, t, timer);
struct input_dev *dev = ml->dev;
unsigned long flags;
pr_debug("timer: updating effects\n");
spin_lock_irqsave(&dev->event_lock, flags);
ml_play_effects(ml);
spin_unlock_irqrestore(&dev->event_lock, flags);
}
/*
* Sets requested gain for FF effects. Called with dev->event_lock held.
*/
static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
{
struct ml_device *ml = dev->ff->private;
int i;
ml->gain = gain;
for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
__clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);
ml_play_effects(ml);
}
/*
* Start/stop specified FF effect. Called with dev->event_lock held.
*/
static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
{
struct ml_device *ml = dev->ff->private;
struct ml_effect_state *state = &ml->states[effect_id];
if (value > 0) {
pr_debug("initiated play\n");
__set_bit(FF_EFFECT_STARTED, &state->flags);
state->count = value;
state->play_at = jiffies +
msecs_to_jiffies(state->effect->replay.delay);
state->stop_at = state->play_at +
msecs_to_jiffies(state->effect->replay.length);
state->adj_at = state->play_at;
} else {
pr_debug("initiated stop\n");
if (test_bit(FF_EFFECT_PLAYING, &state->flags))
__set_bit(FF_EFFECT_ABORTING, &state->flags);
else
__clear_bit(FF_EFFECT_STARTED, &state->flags);
}
ml_play_effects(ml);
return 0;
}
static int ml_ff_upload(struct input_dev *dev,
struct ff_effect *effect, struct ff_effect *old)
{
struct ml_device *ml = dev->ff->private;
struct ml_effect_state *state = &ml->states[effect->id];
spin_lock_irq(&dev->event_lock);
if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
__clear_bit(FF_EFFECT_PLAYING, &state->flags);
state->play_at = jiffies +
msecs_to_jiffies(state->effect->replay.delay);
state->stop_at = state->play_at +
msecs_to_jiffies(state->effect->replay.length);
state->adj_at = state->play_at;
ml_schedule_timer(ml);
}
spin_unlock_irq(&dev->event_lock);
return 0;
}
static void ml_ff_destroy(struct ff_device *ff)
{
struct ml_device *ml = ff->private;
/*
* Even though we stop all playing effects when tearing down
* an input device (via input_device_flush() that calls into
* input_ff_flush() that stops and erases all effects), we
* do not actually stop the timer, and therefore we should
* do it here.
*/
del_timer_sync(&ml->timer);
kfree(ml->private);
}
/**
* input_ff_create_memless() - create memoryless force-feedback device
* @dev: input device supporting force-feedback
* @data: driver-specific data to be passed into @play_effect
* @play_effect: driver-specific method for playing FF effect
*/
int input_ff_create_memless(struct input_dev *dev, void *data,
int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
{
struct ml_device *ml;
struct ff_device *ff;
int error;
int i;
ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
if (!ml)
return -ENOMEM;
ml->dev = dev;
ml->private = data;
ml->play_effect = play_effect;
ml->gain = 0xffff;
timer_setup(&ml->timer, ml_effect_timer, 0);
set_bit(FF_GAIN, dev->ffbit);
error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
if (error) {
kfree(ml);
return error;
}
ff = dev->ff;
ff->private = ml;
ff->upload = ml_ff_upload;
ff->playback = ml_ff_playback;
ff->set_gain = ml_ff_set_gain;
ff->destroy = ml_ff_destroy;
/* we can emulate periodic effects with RUMBLE */
if (test_bit(FF_RUMBLE, ff->ffbit)) {
set_bit(FF_PERIODIC, dev->ffbit);
set_bit(FF_SINE, dev->ffbit);
set_bit(FF_TRIANGLE, dev->ffbit);
set_bit(FF_SQUARE, dev->ffbit);
}
for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
ml->states[i].effect = &ff->effects[i];
return 0;
}
EXPORT_SYMBOL_GPL(input_ff_create_memless);
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