// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * pcm emulation on emu8000 wavetable
 *
 *  Copyright (C) 2002 Takashi Iwai <tiwai@suse.de>
 */

#include "emu8000_local.h"

#include <linux/sched/signal.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <sound/initval.h>
#include <sound/pcm.h>

/*
 * define the following if you want to use this pcm with non-interleaved mode
 */
/* #define USE_NONINTERLEAVE */

/* NOTE: for using the non-interleaved mode with alsa-lib, you have to set
 * mmap_emulation flag to 1 in your .asoundrc, such like
 *
 *      pcm.emu8k {
 *              type plug
 *              slave.pcm {
 *                      type hw
 *                      card 0
 *                      device 1
 *                      mmap_emulation 1
 *              }
 *      }
 *
 * besides, for the time being, the non-interleaved mode doesn't work well on
 * alsa-lib...
 */


struct snd_emu8k_pcm {
        struct snd_emu8000 *emu;
        struct snd_pcm_substream *substream;

        unsigned int allocated_bytes;
        struct snd_util_memblk *block;
        unsigned int offset;
        unsigned int buf_size;
        unsigned int period_size;
        unsigned int loop_start[2];
        unsigned int pitch;
        int panning[2];
        int last_ptr;
        int period_pos;
        int voices;
        unsigned int dram_opened: 1;
        unsigned int running: 1;
        unsigned int timer_running: 1;
        struct timer_list timer;
        spinlock_t timer_lock;
};

#define LOOP_BLANK_SIZE         8


/*
 * open up channels for the simultaneous data transfer and playback
 */
static int
emu8k_open_dram_for_pcm(struct snd_emu8000 *emu, int channels)
{
        int i;

        /* reserve up to 2 voices for playback */
        snd_emux_lock_voice(emu->emu, 0);
        if (channels > 1)
                snd_emux_lock_voice(emu->emu, 1);

        /* reserve 28 voices for loading */
        for (i = channels + 1; i < EMU8000_DRAM_VOICES; i++) {
                unsigned int mode = EMU8000_RAM_WRITE;
                snd_emux_lock_voice(emu->emu, i);
#ifndef USE_NONINTERLEAVE
                if (channels > 1 && (i & 1) != 0)
                        mode |= EMU8000_RAM_RIGHT;
#endif
                snd_emu8000_dma_chan(emu, i, mode);
        }

        /* assign voice 31 and 32 to ROM */
        EMU8000_VTFT_WRITE(emu, 30, 0);
        EMU8000_PSST_WRITE(emu, 30, 0x1d8);
        EMU8000_CSL_WRITE(emu, 30, 0x1e0);
        EMU8000_CCCA_WRITE(emu, 30, 0x1d8);
        EMU8000_VTFT_WRITE(emu, 31, 0);
        EMU8000_PSST_WRITE(emu, 31, 0x1d8);
        EMU8000_CSL_WRITE(emu, 31, 0x1e0);
        EMU8000_CCCA_WRITE(emu, 31, 0x1d8);

        return 0;
}

/*
 */
static void
snd_emu8000_write_wait(struct snd_emu8000 *emu, int can_schedule)
{
        while ((EMU8000_SMALW_READ(emu) & 0x80000000) != 0) {
                if (can_schedule) {
                        schedule_timeout_interruptible(1);
                        if (signal_pending(current))
                                break;
                }
        }
}

/*
 * close all channels
 */
static void
emu8k_close_dram(struct snd_emu8000 *emu)
{
        int i;

        for (i = 0; i < 2; i++)
                snd_emux_unlock_voice(emu->emu, i);
        for (; i < EMU8000_DRAM_VOICES; i++) {
                snd_emu8000_dma_chan(emu, i, EMU8000_RAM_CLOSE);
                snd_emux_unlock_voice(emu->emu, i);
        }
}

/*
 * convert Hz to AWE32 rate offset (see emux/soundfont.c)
 */

#define OFFSET_SAMPLERATE       1011119         /* base = 44100 */
#define SAMPLERATE_RATIO        4096

static int calc_rate_offset(int hz)
{
        return snd_sf_linear_to_log(hz, OFFSET_SAMPLERATE, SAMPLERATE_RATIO);
}


/*
 */

static const struct snd_pcm_hardware emu8k_pcm_hw = {
#ifdef USE_NONINTERLEAVE
        .info =                 SNDRV_PCM_INFO_NONINTERLEAVED,
#else
        .info =                 SNDRV_PCM_INFO_INTERLEAVED,
#endif
        .formats =              SNDRV_PCM_FMTBIT_S16_LE,
        .rates =                SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000,
        .rate_min =             4000,
        .rate_max =             48000,
        .channels_min =         1,
        .channels_max =         2,
        .buffer_bytes_max =     (128*1024),
        .period_bytes_min =     1024,
        .period_bytes_max =     (128*1024),
        .periods_min =          2,
        .periods_max =          1024,
        .fifo_size =            0,

};

/*
 * get the current position at the given channel from CCCA register
 */
static inline int emu8k_get_curpos(struct snd_emu8k_pcm *rec, int ch)
{
        int val = EMU8000_CCCA_READ(rec->emu, ch) & 0xfffffff;
        val -= rec->loop_start[ch] - 1;
        return val;
}


/*
 * timer interrupt handler
 * check the current position and update the period if necessary.
 */
static void emu8k_pcm_timer_func(struct timer_list *t)
{
        struct snd_emu8k_pcm *rec = from_timer(rec, t, timer);
        int ptr, delta;

        spin_lock(&rec->timer_lock);
        /* update the current pointer */
        ptr = emu8k_get_curpos(rec, 0);
        if (ptr < rec->last_ptr)
                delta = ptr + rec->buf_size - rec->last_ptr;
        else
                delta = ptr - rec->last_ptr;
        rec->period_pos += delta;
        rec->last_ptr = ptr;

        /* reprogram timer */
        mod_timer(&rec->timer, jiffies + 1);

        /* update period */
        if (rec->period_pos >= (int)rec->period_size) {
                rec->period_pos %= rec->period_size;
                spin_unlock(&rec->timer_lock);
                snd_pcm_period_elapsed(rec->substream);
                return;
        }
        spin_unlock(&rec->timer_lock);
}


/*
 * open pcm
 * creating an instance here
 */
static int emu8k_pcm_open(struct snd_pcm_substream *subs)
{
        struct snd_emu8000 *emu = snd_pcm_substream_chip(subs);
        struct snd_emu8k_pcm *rec;
        struct snd_pcm_runtime *runtime = subs->runtime;

        rec = kzalloc(sizeof(*rec), GFP_KERNEL);
        if (! rec)
                return -ENOMEM;

        rec->emu = emu;
        rec->substream = subs;
        runtime->private_data = rec;

        spin_lock_init(&rec->timer_lock);
        timer_setup(&rec->timer, emu8k_pcm_timer_func, 0);

        runtime->hw = emu8k_pcm_hw;
        runtime->hw.buffer_bytes_max = emu->mem_size - LOOP_BLANK_SIZE * 3;
        runtime->hw.period_bytes_max = runtime->hw.buffer_bytes_max / 2;

        /* use timer to update periods.. (specified in msec) */
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME,
                                     (1000000 + HZ - 1) / HZ, UINT_MAX);

        return 0;
}

static int emu8k_pcm_close(struct snd_pcm_substream *subs)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;
        kfree(rec);
        subs->runtime->private_data = NULL;
        return 0;
}

/*
 * calculate pitch target
 */
static int calc_pitch_target(int pitch)
{
        int ptarget = 1 << (pitch >> 12);
        if (pitch & 0x800) ptarget += (ptarget * 0x102e) / 0x2710;
        if (pitch & 0x400) ptarget += (ptarget * 0x764) / 0x2710;
        if (pitch & 0x200) ptarget += (ptarget * 0x389) / 0x2710;
        ptarget += (ptarget >> 1);
        if (ptarget > 0xffff) ptarget = 0xffff;
        return ptarget;
}

/*
 * set up the voice
 */
static void setup_voice(struct snd_emu8k_pcm *rec, int ch)
{
        struct snd_emu8000 *hw = rec->emu;
        unsigned int temp;

        /* channel to be silent and idle */
        EMU8000_DCYSUSV_WRITE(hw, ch, 0x0080);
        EMU8000_VTFT_WRITE(hw, ch, 0x0000FFFF);
        EMU8000_CVCF_WRITE(hw, ch, 0x0000FFFF);
        EMU8000_PTRX_WRITE(hw, ch, 0);
        EMU8000_CPF_WRITE(hw, ch, 0);

        /* pitch offset */
        EMU8000_IP_WRITE(hw, ch, rec->pitch);
        /* set envelope parameters */
        EMU8000_ENVVAL_WRITE(hw, ch, 0x8000);
        EMU8000_ATKHLD_WRITE(hw, ch, 0x7f7f);
        EMU8000_DCYSUS_WRITE(hw, ch, 0x7f7f);
        EMU8000_ENVVOL_WRITE(hw, ch, 0x8000);
        EMU8000_ATKHLDV_WRITE(hw, ch, 0x7f7f);
        /* decay/sustain parameter for volume envelope is used
           for triggerg the voice */
        /* modulation envelope heights */
        EMU8000_PEFE_WRITE(hw, ch, 0x0);
        /* lfo1/2 delay */
        EMU8000_LFO1VAL_WRITE(hw, ch, 0x8000);
        EMU8000_LFO2VAL_WRITE(hw, ch, 0x8000);
        /* lfo1 pitch & cutoff shift */
        EMU8000_FMMOD_WRITE(hw, ch, 0);
        /* lfo1 volume & freq */
        EMU8000_TREMFRQ_WRITE(hw, ch, 0);
        /* lfo2 pitch & freq */
        EMU8000_FM2FRQ2_WRITE(hw, ch, 0);
        /* pan & loop start */
        temp = rec->panning[ch];
        temp = (temp <<24) | ((unsigned int)rec->loop_start[ch] - 1);
        EMU8000_PSST_WRITE(hw, ch, temp);
        /* chorus & loop end (chorus 8bit, MSB) */
        temp = 0; // chorus
        temp = (temp << 24) | ((unsigned int)rec->loop_start[ch] + rec->buf_size - 1);
        EMU8000_CSL_WRITE(hw, ch, temp);
        /* Q & current address (Q 4bit value, MSB) */
        temp = 0; // filterQ
        temp = (temp << 28) | ((unsigned int)rec->loop_start[ch] - 1);
        EMU8000_CCCA_WRITE(hw, ch, temp);
        /* clear unknown registers */
        EMU8000_00A0_WRITE(hw, ch, 0);
        EMU8000_0080_WRITE(hw, ch, 0);
}

/*
 * trigger the voice
 */
static void start_voice(struct snd_emu8k_pcm *rec, int ch)
{
        unsigned long flags;
        struct snd_emu8000 *hw = rec->emu;
        unsigned int temp, aux;
        int pt = calc_pitch_target(rec->pitch);

        /* cutoff and volume */
        EMU8000_IFATN_WRITE(hw, ch, 0xff00);
        EMU8000_VTFT_WRITE(hw, ch, 0xffff);
        EMU8000_CVCF_WRITE(hw, ch, 0xffff);
        /* trigger envelope */
        EMU8000_DCYSUSV_WRITE(hw, ch, 0x7f7f);
        /* set reverb and pitch target */
        temp = 0; // reverb
        if (rec->panning[ch] == 0)
                aux = 0xff;
        else
                aux = (-rec->panning[ch]) & 0xff;
        temp = (temp << 8) | (pt << 16) | aux;
        EMU8000_PTRX_WRITE(hw, ch, temp);
        EMU8000_CPF_WRITE(hw, ch, pt << 16);

        /* start timer */
        spin_lock_irqsave(&rec->timer_lock, flags);
        if (! rec->timer_running) {
                mod_timer(&rec->timer, jiffies + 1);
                rec->timer_running = 1;
        }
        spin_unlock_irqrestore(&rec->timer_lock, flags);
}

/*
 * stop the voice immediately
 */
static void stop_voice(struct snd_emu8k_pcm *rec, int ch)
{
        unsigned long flags;
        struct snd_emu8000 *hw = rec->emu;

        EMU8000_DCYSUSV_WRITE(hw, ch, 0x807F);

        /* stop timer */
        spin_lock_irqsave(&rec->timer_lock, flags);
        if (rec->timer_running) {
                del_timer(&rec->timer);
                rec->timer_running = 0;
        }
        spin_unlock_irqrestore(&rec->timer_lock, flags);
}

static int emu8k_pcm_trigger(struct snd_pcm_substream *subs, int cmd)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;
        int ch;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
                for (ch = 0; ch < rec->voices; ch++)
                        start_voice(rec, ch);
                rec->running = 1;
                break;
        case SNDRV_PCM_TRIGGER_STOP:
                rec->running = 0;
                for (ch = 0; ch < rec->voices; ch++)
                        stop_voice(rec, ch);
                break;
        default:
                return -EINVAL;
        }
        return 0;
}


/*
 * copy / silence ops
 */

/*
 * this macro should be inserted in the copy/silence loops
 * to reduce the latency.  without this, the system will hang up
 * during the whole loop.
 */
#define CHECK_SCHEDULER() \
do { \
        cond_resched();\
        if (signal_pending(current))\
                return -EAGAIN;\
} while (0)

enum {
        COPY_USER, COPY_KERNEL, FILL_SILENCE,
};

#define GET_VAL(sval, buf, mode)                                        \
        do {                                                            \
                switch (mode) {                                         \
                case FILL_SILENCE:                                      \
                        sval = 0;                                       \
                        break;                                          \
                case COPY_KERNEL:                                       \
                        sval = *buf++;                                  \
                        break;                                          \
                default:                                                \
                        if (get_user(sval, (unsigned short __user *)buf)) \
                                return -EFAULT;                         \
                        buf++;                                          \
                        break;                                          \
                }                                                       \
        } while (0)

#ifdef USE_NONINTERLEAVE

#define LOOP_WRITE(rec, offset, _buf, count, mode)              \
        do {                                                    \
                struct snd_emu8000 *emu = (rec)->emu;           \
                unsigned short *buf = (unsigned short *)(_buf); \
                snd_emu8000_write_wait(emu, 1);                 \
                EMU8000_SMALW_WRITE(emu, offset);               \
                while (count > 0) {                             \
                        unsigned short sval;                    \
                        CHECK_SCHEDULER();                      \
                        GET_VAL(sval, buf, mode);               \
                        EMU8000_SMLD_WRITE(emu, sval);          \
                        count--;                                \
                }                                               \
        } while (0)

/* copy one channel block */
static int emu8k_pcm_copy(struct snd_pcm_substream *subs,
                          int voice, unsigned long pos,
                          void __user *src, unsigned long count)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        /* convert to word unit */
        pos = (pos << 1) + rec->loop_start[voice];
        count <<= 1;
        LOOP_WRITE(rec, pos, src, count, COPY_USER);
        return 0;
}

static int emu8k_pcm_copy_kernel(struct snd_pcm_substream *subs,
                                 int voice, unsigned long pos,
                                 void *src, unsigned long count)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        /* convert to word unit */
        pos = (pos << 1) + rec->loop_start[voice];
        count <<= 1;
        LOOP_WRITE(rec, pos, src, count, COPY_KERNEL);
        return 0;
}

/* make a channel block silence */
static int emu8k_pcm_silence(struct snd_pcm_substream *subs,
                             int voice, unsigned long pos, unsigned long count)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        /* convert to word unit */
        pos = (pos << 1) + rec->loop_start[voice];
        count <<= 1;
        LOOP_WRITE(rec, pos, NULL, count, FILL_SILENCE);
        return 0;
}

#else /* interleave */

#define LOOP_WRITE(rec, pos, _buf, count, mode)                         \
        do {                                                            \
                struct snd_emu8000 *emu = rec->emu;                     \
                unsigned short *buf = (unsigned short *)(_buf);         \
                snd_emu8000_write_wait(emu, 1);                         \
                EMU8000_SMALW_WRITE(emu, pos + rec->loop_start[0]);     \
                if (rec->voices > 1)                                    \
                        EMU8000_SMARW_WRITE(emu, pos + rec->loop_start[1]); \
                while (count > 0) {                                     \
                        unsigned short sval;                            \
                        CHECK_SCHEDULER();                              \
                        GET_VAL(sval, buf, mode);                       \
                        EMU8000_SMLD_WRITE(emu, sval);                  \
                        if (rec->voices > 1) {                          \
                                CHECK_SCHEDULER();                      \
                                GET_VAL(sval, buf, mode);               \
                                EMU8000_SMRD_WRITE(emu, sval);          \
                        }                                               \
                        count--;                                        \
                }                                                       \
        } while (0)


/*
 * copy the interleaved data can be done easily by using
 * DMA "left" and "right" channels on emu8k engine.
 */
static int emu8k_pcm_copy(struct snd_pcm_substream *subs,
                          int voice, unsigned long pos,
                          void __user *src, unsigned long count)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        /* convert to frames */
        pos = bytes_to_frames(subs->runtime, pos);
        count = bytes_to_frames(subs->runtime, count);
        LOOP_WRITE(rec, pos, src, count, COPY_USER);
        return 0;
}

static int emu8k_pcm_copy_kernel(struct snd_pcm_substream *subs,
                                 int voice, unsigned long pos,
                                 void *src, unsigned long count)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        /* convert to frames */
        pos = bytes_to_frames(subs->runtime, pos);
        count = bytes_to_frames(subs->runtime, count);
        LOOP_WRITE(rec, pos, src, count, COPY_KERNEL);
        return 0;
}

static int emu8k_pcm_silence(struct snd_pcm_substream *subs,
                             int voice, unsigned long pos, unsigned long count)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        /* convert to frames */
        pos = bytes_to_frames(subs->runtime, pos);
        count = bytes_to_frames(subs->runtime, count);
        LOOP_WRITE(rec, pos, NULL, count, FILL_SILENCE);
        return 0;
}
#endif


/*
 * allocate a memory block
 */
static int emu8k_pcm_hw_params(struct snd_pcm_substream *subs,
                               struct snd_pcm_hw_params *hw_params)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        if (rec->block) {
                /* reallocation - release the old block */
                snd_util_mem_free(rec->emu->memhdr, rec->block);
                rec->block = NULL;
        }

        rec->allocated_bytes = params_buffer_bytes(hw_params) + LOOP_BLANK_SIZE * 4;
        rec->block = snd_util_mem_alloc(rec->emu->memhdr, rec->allocated_bytes);
        if (! rec->block)
                return -ENOMEM;
        rec->offset = EMU8000_DRAM_OFFSET + (rec->block->offset >> 1); /* in word */
        /* at least dma_bytes must be set for non-interleaved mode */
        subs->dma_buffer.bytes = params_buffer_bytes(hw_params);

        return 0;
}

/*
 * free the memory block
 */
static int emu8k_pcm_hw_free(struct snd_pcm_substream *subs)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        if (rec->block) {
                int ch;
                for (ch = 0; ch < rec->voices; ch++)
                        stop_voice(rec, ch); // to be sure
                if (rec->dram_opened)
                        emu8k_close_dram(rec->emu);
                snd_util_mem_free(rec->emu->memhdr, rec->block);
                rec->block = NULL;
        }
        return 0;
}

/*
 */
static int emu8k_pcm_prepare(struct snd_pcm_substream *subs)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;

        rec->pitch = 0xe000 + calc_rate_offset(subs->runtime->rate);
        rec->last_ptr = 0;
        rec->period_pos = 0;

        rec->buf_size = subs->runtime->buffer_size;
        rec->period_size = subs->runtime->period_size;
        rec->voices = subs->runtime->channels;
        rec->loop_start[0] = rec->offset + LOOP_BLANK_SIZE;
        if (rec->voices > 1)
                rec->loop_start[1] = rec->loop_start[0] + rec->buf_size + LOOP_BLANK_SIZE;
        if (rec->voices > 1) {
                rec->panning[0] = 0xff;
                rec->panning[1] = 0x00;
        } else
                rec->panning[0] = 0x80;

        if (! rec->dram_opened) {
                int err, i, ch;

                snd_emux_terminate_all(rec->emu->emu);
                if ((err = emu8k_open_dram_for_pcm(rec->emu, rec->voices)) != 0)
                        return err;
                rec->dram_opened = 1;

                /* clear loop blanks */
                snd_emu8000_write_wait(rec->emu, 0);
                EMU8000_SMALW_WRITE(rec->emu, rec->offset);
                for (i = 0; i < LOOP_BLANK_SIZE; i++)
                        EMU8000_SMLD_WRITE(rec->emu, 0);
                for (ch = 0; ch < rec->voices; ch++) {
                        EMU8000_SMALW_WRITE(rec->emu, rec->loop_start[ch] + rec->buf_size);
                        for (i = 0; i < LOOP_BLANK_SIZE; i++)
                                EMU8000_SMLD_WRITE(rec->emu, 0);
                }
        }

        setup_voice(rec, 0);
        if (rec->voices > 1)
                setup_voice(rec, 1);
        return 0;
}

static snd_pcm_uframes_t emu8k_pcm_pointer(struct snd_pcm_substream *subs)
{
        struct snd_emu8k_pcm *rec = subs->runtime->private_data;
        if (rec->running)
                return emu8k_get_curpos(rec, 0);
        return 0;
}


static const struct snd_pcm_ops emu8k_pcm_ops = {
        .open =         emu8k_pcm_open,
        .close =        emu8k_pcm_close,
        .ioctl =        snd_pcm_lib_ioctl,
        .hw_params =    emu8k_pcm_hw_params,
        .hw_free =      emu8k_pcm_hw_free,
        .prepare =      emu8k_pcm_prepare,
        .trigger =      emu8k_pcm_trigger,
        .pointer =      emu8k_pcm_pointer,
        .copy_user =    emu8k_pcm_copy,
        .copy_kernel =  emu8k_pcm_copy_kernel,
        .fill_silence = emu8k_pcm_silence,
};


static void snd_emu8000_pcm_free(struct snd_pcm *pcm)
{
        struct snd_emu8000 *emu = pcm->private_data;
        emu->pcm = NULL;
}

int snd_emu8000_pcm_new(struct snd_card *card, struct snd_emu8000 *emu, int index)
{
        struct snd_pcm *pcm;
        int err;

        if ((err = snd_pcm_new(card, "Emu8000 PCM", index, 1, 0, &pcm)) < 0)
                return err;
        pcm->private_data = emu;
        pcm->private_free = snd_emu8000_pcm_free;
        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &emu8k_pcm_ops);
        emu->pcm = pcm;

        snd_device_register(card, pcm);

        return 0;
}