1 files changed, 553 insertions, 0 deletions

diff --git a/drivers/input/ff-memless.c b/drivers/input/ff-memless.c
new file mode 100644
index 0000000000..c321cdabd2
--- /dev/null
+++ b/drivers/input/ff-memless.c
@@ -0,0 +1,553 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Force feedback support for memoryless devices
+ *
+ *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
+ *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
+ */
+
+/* #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 <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(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);