// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   ALSA sequencer Timer
 *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
 *                              Jaroslav Kysela <perex@perex.cz>
 */

#include <sound/core.h>
#include <linux/slab.h>
#include "seq_timer.h"
#include "seq_queue.h"
#include "seq_info.h"

/* allowed sequencer timer frequencies, in Hz */
#define MIN_FREQUENCY           10
#define MAX_FREQUENCY           6250
#define DEFAULT_FREQUENCY       1000

#define SKEW_BASE       0x10000 /* 16bit shift */

static void snd_seq_timer_set_tick_resolution(struct snd_seq_timer *tmr)
{
        unsigned int threshold =
                tmr->tempo_base == 1000 ? 1000000 : 10000;

        if (tmr->tempo < threshold)
                tmr->tick.resolution = (tmr->tempo * tmr->tempo_base) / tmr->ppq;
        else {
                /* might overflow.. */
                unsigned int s;
                s = tmr->tempo % tmr->ppq;
                s = (s * tmr->tempo_base) / tmr->ppq;
                tmr->tick.resolution = (tmr->tempo / tmr->ppq) * tmr->tempo_base;
                tmr->tick.resolution += s;
        }
        if (tmr->tick.resolution <= 0)
                tmr->tick.resolution = 1;
        snd_seq_timer_update_tick(&tmr->tick, 0);
}

/* create new timer (constructor) */
struct snd_seq_timer *snd_seq_timer_new(void)
{
        struct snd_seq_timer *tmr;
        
        tmr = kzalloc_obj(*tmr);
        if (!tmr)
                return NULL;
        spin_lock_init(&tmr->lock);

        /* reset setup to defaults */
        snd_seq_timer_defaults(tmr);
        
        /* reset time */
        snd_seq_timer_reset(tmr);
        
        return tmr;
}

/* delete timer (destructor) */
void snd_seq_timer_delete(struct snd_seq_timer **tmr)
{
        struct snd_seq_timer *t = *tmr;
        *tmr = NULL;

        if (t == NULL) {
                pr_debug("ALSA: seq: snd_seq_timer_delete() called with NULL timer\n");
                return;
        }
        t->running = 0;

        /* reset time */
        snd_seq_timer_stop(t);
        snd_seq_timer_reset(t);

        kfree(t);
}

void snd_seq_timer_defaults(struct snd_seq_timer * tmr)
{
        guard(spinlock_irqsave)(&tmr->lock);
        /* setup defaults */
        tmr->ppq = 96;          /* 96 PPQ */
        tmr->tempo = 500000;    /* 120 BPM */
        tmr->tempo_base = 1000; /* 1us */
        snd_seq_timer_set_tick_resolution(tmr);
        tmr->running = 0;

        tmr->type = SNDRV_SEQ_TIMER_ALSA;
        tmr->alsa_id.dev_class = seq_default_timer_class;
        tmr->alsa_id.dev_sclass = seq_default_timer_sclass;
        tmr->alsa_id.card = seq_default_timer_card;
        tmr->alsa_id.device = seq_default_timer_device;
        tmr->alsa_id.subdevice = seq_default_timer_subdevice;
        tmr->preferred_resolution = seq_default_timer_resolution;

        tmr->skew = tmr->skew_base = SKEW_BASE;
}

static void seq_timer_reset(struct snd_seq_timer *tmr)
{
        /* reset time & songposition */
        tmr->cur_time.tv_sec = 0;
        tmr->cur_time.tv_nsec = 0;

        tmr->tick.cur_tick = 0;
        tmr->tick.fraction = 0;
}

void snd_seq_timer_reset(struct snd_seq_timer *tmr)
{
        guard(spinlock_irqsave)(&tmr->lock);
        seq_timer_reset(tmr);
}


/* called by timer interrupt routine. the period time since previous invocation is passed */
static void snd_seq_timer_interrupt(struct snd_timer_instance *timeri,
                                    unsigned long resolution,
                                    unsigned long ticks)
{
        struct snd_seq_queue *q = timeri->callback_data;
        struct snd_seq_timer *tmr;

        if (q == NULL)
                return;
        tmr = q->timer;
        if (tmr == NULL)
                return;

        scoped_guard(spinlock_irqsave, &tmr->lock) {
                if (!tmr->running)
                        return;

                resolution *= ticks;
                if (tmr->skew != tmr->skew_base) {
                        /* FIXME: assuming skew_base = 0x10000 */
                        resolution = (resolution >> 16) * tmr->skew +
                                (((resolution & 0xffff) * tmr->skew) >> 16);
                }

                /* update timer */
                snd_seq_inc_time_nsec(&tmr->cur_time, resolution);

                /* calculate current tick */
                snd_seq_timer_update_tick(&tmr->tick, resolution);

                /* register actual time of this timer update */
                ktime_get_ts64(&tmr->last_update);
        }

        /* check queues and dispatch events */
        snd_seq_check_queue(q, 1, 0);
}

/* set current tempo */
int snd_seq_timer_set_tempo(struct snd_seq_timer * tmr, int tempo)
{
        if (snd_BUG_ON(!tmr))
                return -EINVAL;
        if (tempo <= 0)
                return -EINVAL;
        guard(spinlock_irqsave)(&tmr->lock);
        if ((unsigned int)tempo != tmr->tempo) {
                tmr->tempo = tempo;
                snd_seq_timer_set_tick_resolution(tmr);
        }
        return 0;
}

/* set current tempo, ppq and base in a shot */
int snd_seq_timer_set_tempo_ppq(struct snd_seq_timer *tmr, int tempo, int ppq,
                                unsigned int tempo_base)
{
        int changed;

        if (snd_BUG_ON(!tmr))
                return -EINVAL;
        if (tempo <= 0 || ppq <= 0)
                return -EINVAL;
        /* allow only 10ns or 1us tempo base for now */
        if (tempo_base && tempo_base != 10 && tempo_base != 1000)
                return -EINVAL;
        guard(spinlock_irqsave)(&tmr->lock);
        if (tmr->running && (ppq != tmr->ppq)) {
                /* refuse to change ppq on running timers */
                /* because it will upset the song position (ticks) */
                pr_debug("ALSA: seq: cannot change ppq of a running timer\n");
                return -EBUSY;
        }
        changed = (tempo != tmr->tempo) || (ppq != tmr->ppq);
        tmr->tempo = tempo;
        tmr->ppq = ppq;
        tmr->tempo_base = tempo_base ? tempo_base : 1000;
        if (changed)
                snd_seq_timer_set_tick_resolution(tmr);
        return 0;
}

/* set current tick position */
int snd_seq_timer_set_position_tick(struct snd_seq_timer *tmr,
                                    snd_seq_tick_time_t position)
{
        if (snd_BUG_ON(!tmr))
                return -EINVAL;

        guard(spinlock_irqsave)(&tmr->lock);
        tmr->tick.cur_tick = position;
        tmr->tick.fraction = 0;
        return 0;
}

/* set current real-time position */
int snd_seq_timer_set_position_time(struct snd_seq_timer *tmr,
                                    snd_seq_real_time_t position)
{
        if (snd_BUG_ON(!tmr))
                return -EINVAL;

        snd_seq_sanity_real_time(&position);
        guard(spinlock_irqsave)(&tmr->lock);
        tmr->cur_time = position;
        return 0;
}

/* set timer skew */
int snd_seq_timer_set_skew(struct snd_seq_timer *tmr, unsigned int skew,
                           unsigned int base)
{
        if (snd_BUG_ON(!tmr))
                return -EINVAL;

        /* FIXME */
        if (base != SKEW_BASE) {
                pr_debug("ALSA: seq: invalid skew base 0x%x\n", base);
                return -EINVAL;
        }
        guard(spinlock_irqsave)(&tmr->lock);
        tmr->skew = skew;
        return 0;
}

int snd_seq_timer_open(struct snd_seq_queue *q)
{
        struct snd_timer_instance *t;
        struct snd_seq_timer *tmr;
        char str[32];
        int err;

        tmr = q->timer;
        if (snd_BUG_ON(!tmr))
                return -EINVAL;
        if (tmr->timeri)
                return -EBUSY;
        sprintf(str, "sequencer queue %i", q->queue);
        if (tmr->type != SNDRV_SEQ_TIMER_ALSA)  /* standard ALSA timer */
                return -EINVAL;
        if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE)
                tmr->alsa_id.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
        t = snd_timer_instance_new(str);
        if (!t)
                return -ENOMEM;
        t->callback = snd_seq_timer_interrupt;
        t->callback_data = q;
        t->flags |= SNDRV_TIMER_IFLG_AUTO;
        err = snd_timer_open(t, &tmr->alsa_id, q->queue);
        if (err < 0 && tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE) {
                if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_GLOBAL ||
                    tmr->alsa_id.device != SNDRV_TIMER_GLOBAL_SYSTEM) {
                        struct snd_timer_id tid;
                        memset(&tid, 0, sizeof(tid));
                        tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
                        tid.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
                        tid.card = -1;
                        tid.device = SNDRV_TIMER_GLOBAL_SYSTEM;
                        err = snd_timer_open(t, &tid, q->queue);
                }
        }
        if (err < 0) {
                pr_err("ALSA: seq fatal error: cannot create timer (%i)\n", err);
                snd_timer_instance_free(t);
                return err;
        }
        scoped_guard(spinlock_irq, &tmr->lock) {
                if (tmr->timeri)
                        err = -EBUSY;
                else
                        tmr->timeri = t;
        }
        if (err < 0) {
                snd_timer_close(t);
                snd_timer_instance_free(t);
                return err;
        }
        return 0;
}

int snd_seq_timer_close(struct snd_seq_queue *q)
{
        struct snd_seq_timer *tmr;
        struct snd_timer_instance *t;
        
        tmr = q->timer;
        if (snd_BUG_ON(!tmr))
                return -EINVAL;
        scoped_guard(spinlock_irq, &tmr->lock) {
                t = tmr->timeri;
                tmr->timeri = NULL;
        }
        if (t) {
                snd_timer_close(t);
                snd_timer_instance_free(t);
        }
        return 0;
}

static int seq_timer_stop(struct snd_seq_timer *tmr)
{
        if (! tmr->timeri)
                return -EINVAL;
        if (!tmr->running)
                return 0;
        tmr->running = 0;
        snd_timer_pause(tmr->timeri);
        return 0;
}

int snd_seq_timer_stop(struct snd_seq_timer *tmr)
{
        guard(spinlock_irqsave)(&tmr->lock);
        return seq_timer_stop(tmr);
}

static int initialize_timer(struct snd_seq_timer *tmr)
{
        struct snd_timer *t;
        unsigned long freq;

        t = tmr->timeri->timer;
        if (!t)
                return -EINVAL;

        freq = tmr->preferred_resolution;
        if (!freq)
                freq = DEFAULT_FREQUENCY;
        else if (freq < MIN_FREQUENCY)
                freq = MIN_FREQUENCY;
        else if (freq > MAX_FREQUENCY)
                freq = MAX_FREQUENCY;

        tmr->ticks = 1;
        if (!(t->hw.flags & SNDRV_TIMER_HW_SLAVE)) {
                unsigned long r = snd_timer_resolution(tmr->timeri);
                if (r) {
                        tmr->ticks = (unsigned int)(1000000000uL / (r * freq));
                        if (! tmr->ticks)
                                tmr->ticks = 1;
                }
        }
        tmr->initialized = 1;
        return 0;
}

static int seq_timer_start(struct snd_seq_timer *tmr)
{
        if (! tmr->timeri)
                return -EINVAL;
        if (tmr->running)
                seq_timer_stop(tmr);
        seq_timer_reset(tmr);
        if (initialize_timer(tmr) < 0)
                return -EINVAL;
        snd_timer_start(tmr->timeri, tmr->ticks);
        tmr->running = 1;
        ktime_get_ts64(&tmr->last_update);
        return 0;
}

int snd_seq_timer_start(struct snd_seq_timer *tmr)
{
        guard(spinlock_irqsave)(&tmr->lock);
        return seq_timer_start(tmr);
}

static int seq_timer_continue(struct snd_seq_timer *tmr)
{
        if (! tmr->timeri)
                return -EINVAL;
        if (tmr->running)
                return -EBUSY;
        if (! tmr->initialized) {
                seq_timer_reset(tmr);
                if (initialize_timer(tmr) < 0)
                        return -EINVAL;
        }
        snd_timer_start(tmr->timeri, tmr->ticks);
        tmr->running = 1;
        ktime_get_ts64(&tmr->last_update);
        return 0;
}

int snd_seq_timer_continue(struct snd_seq_timer *tmr)
{
        guard(spinlock_irqsave)(&tmr->lock);
        return seq_timer_continue(tmr);
}

/* return current 'real' time. use timeofday() to get better granularity. */
snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr,
                                               bool adjust_ktime)
{
        snd_seq_real_time_t cur_time;

        guard(spinlock_irqsave)(&tmr->lock);
        cur_time = tmr->cur_time;
        if (adjust_ktime && tmr->running) {
                struct timespec64 tm;

                ktime_get_ts64(&tm);
                tm = timespec64_sub(tm, tmr->last_update);
                cur_time.tv_nsec += tm.tv_nsec;
                cur_time.tv_sec += tm.tv_sec;
                snd_seq_sanity_real_time(&cur_time);
        }
        return cur_time;        
}

/* TODO: use interpolation on tick queue (will only be useful for very
 high PPQ values) */
snd_seq_tick_time_t snd_seq_timer_get_cur_tick(struct snd_seq_timer *tmr)
{
        guard(spinlock_irqsave)(&tmr->lock);
        return tmr->tick.cur_tick;
}


#ifdef CONFIG_SND_PROC_FS
/* exported to seq_info.c */
void snd_seq_info_timer_read(struct snd_info_entry *entry,
                             struct snd_info_buffer *buffer)
{
        int idx;
        struct snd_seq_timer *tmr;
        struct snd_timer_instance *ti;
        unsigned long resolution;
        
        for (idx = 0; idx < SNDRV_SEQ_MAX_QUEUES; idx++) {
                struct snd_seq_queue *q __free(snd_seq_queue) = queueptr(idx);

                if (q == NULL)
                        continue;
                scoped_guard(mutex, &q->timer_mutex) {
                        tmr = q->timer;
                        if (!tmr)
                                break;
                        ti = tmr->timeri;
                        if (!ti)
                                break;
                        snd_iprintf(buffer, "Timer for queue %i : %s\n", q->queue, ti->timer->name);
                        resolution = snd_timer_resolution(ti) * tmr->ticks;
                        snd_iprintf(buffer, "  Period time : %lu.%09lu\n", resolution / 1000000000, resolution % 1000000000);
                        snd_iprintf(buffer, "  Skew : %u / %u\n", tmr->skew, tmr->skew_base);
                }
        }
}
#endif /* CONFIG_SND_PROC_FS */