// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Driver for SiS7019 Audio Accelerator
 *
 *  Copyright (C) 2004-2007, David Dillow
 *  Written by David Dillow <dave@thedillows.org>
 *  Inspired by the Trident 4D-WaveDX/NX driver.
 *
 *  All rights reserved.
 */

#include <linux/init.h>
#include <linux/pci.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <sound/core.h>
#include <sound/ac97_codec.h>
#include <sound/initval.h>
#include "sis7019.h"

MODULE_AUTHOR("David Dillow <dave@thedillows.org>");
MODULE_DESCRIPTION("SiS7019");
MODULE_LICENSE("GPL");

static int index = SNDRV_DEFAULT_IDX1;  /* Index 0-MAX */
static char *id = SNDRV_DEFAULT_STR1;   /* ID for this card */
static bool enable = 1;
static int codecs = 1;

module_param(index, int, 0444);
MODULE_PARM_DESC(index, "Index value for SiS7019 Audio Accelerator.");
module_param(id, charp, 0444);
MODULE_PARM_DESC(id, "ID string for SiS7019 Audio Accelerator.");
module_param(enable, bool, 0444);
MODULE_PARM_DESC(enable, "Enable SiS7019 Audio Accelerator.");
module_param(codecs, int, 0444);
MODULE_PARM_DESC(codecs, "Set bit to indicate that codec number is expected to be present (default 1)");

static const struct pci_device_id snd_sis7019_ids[] = {
        { PCI_DEVICE(PCI_VENDOR_ID_SI, 0x7019) },
        { 0, }
};

MODULE_DEVICE_TABLE(pci, snd_sis7019_ids);

/* There are three timing modes for the voices.
 *
 * For both playback and capture, when the buffer is one or two periods long,
 * we use the hardware's built-in Mid-Loop Interrupt and End-Loop Interrupt
 * to let us know when the periods have ended.
 *
 * When performing playback with more than two periods per buffer, we set
 * the "Stop Sample Offset" and tell the hardware to interrupt us when we
 * reach it. We then update the offset and continue on until we are
 * interrupted for the next period.
 *
 * Capture channels do not have a SSO, so we allocate a playback channel to
 * use as a timer for the capture periods. We use the SSO on the playback
 * channel to clock out virtual periods, and adjust the virtual period length
 * to maintain synchronization. This algorithm came from the Trident driver.
 *
 * FIXME: It'd be nice to make use of some of the synth features in the
 * hardware, but a woeful lack of documentation is a significant roadblock.
 */
struct voice {
        u16 flags;
#define         VOICE_IN_USE            1
#define         VOICE_CAPTURE           2
#define         VOICE_SSO_TIMING        4
#define         VOICE_SYNC_TIMING       8
        u16 sync_cso;
        u16 period_size;
        u16 buffer_size;
        u16 sync_period_size;
        u16 sync_buffer_size;
        u32 sso;
        u32 vperiod;
        struct snd_pcm_substream *substream;
        struct voice *timing;
        void __iomem *ctrl_base;
        void __iomem *wave_base;
        void __iomem *sync_base;
        int num;
};

/* We need four pages to store our wave parameters during a suspend. If
 * we're not doing power management, we still need to allocate a page
 * for the silence buffer.
 */
#define SIS_SUSPEND_PAGES       4

struct sis7019 {
        unsigned long ioport;
        void __iomem *ioaddr;
        int irq;
        int codecs_present;

        struct pci_dev *pci;
        struct snd_pcm *pcm;
        struct snd_card *card;
        struct snd_ac97 *ac97[3];

        /* Protect against more than one thread hitting the AC97
         * registers (in a more polite manner than pounding the hardware
         * semaphore)
         */
        struct mutex ac97_mutex;

        /* voice_lock protects allocation/freeing of the voice descriptions
         */
        spinlock_t voice_lock;

        struct voice voices[64];
        struct voice capture_voice;

        /* Allocate pages to store the internal wave state during
         * suspends. When we're operating, this can be used as a silence
         * buffer for a timing channel.
         */
        void *suspend_state[SIS_SUSPEND_PAGES];

        int silence_users;
        dma_addr_t silence_dma_addr;
};

/* These values are also used by the module param 'codecs' to indicate
 * which codecs should be present.
 */
#define SIS_PRIMARY_CODEC_PRESENT       0x0001
#define SIS_SECONDARY_CODEC_PRESENT     0x0002
#define SIS_TERTIARY_CODEC_PRESENT      0x0004

/* The HW offset parameters (Loop End, Stop Sample, End Sample) have a
 * documented range of 8-0xfff8 samples. Given that they are 0-based,
 * that places our period/buffer range at 9-0xfff9 samples. That makes the
 * max buffer size 0xfff9 samples * 2 channels * 2 bytes per sample, and
 * max samples / min samples gives us the max periods in a buffer.
 *
 * We'll add a constraint upon open that limits the period and buffer sample
 * size to values that are legal for the hardware.
 */
static const struct snd_pcm_hardware sis_playback_hw_info = {
        .info = (SNDRV_PCM_INFO_MMAP |
                 SNDRV_PCM_INFO_MMAP_VALID |
                 SNDRV_PCM_INFO_INTERLEAVED |
                 SNDRV_PCM_INFO_BLOCK_TRANSFER |
                 SNDRV_PCM_INFO_SYNC_START |
                 SNDRV_PCM_INFO_RESUME),
        .formats = (SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_U8 |
                    SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_U16_LE),
        .rates = SNDRV_PCM_RATE_8000_48000 | SNDRV_PCM_RATE_CONTINUOUS,
        .rate_min = 4000,
        .rate_max = 48000,
        .channels_min = 1,
        .channels_max = 2,
        .buffer_bytes_max = (0xfff9 * 4),
        .period_bytes_min = 9,
        .period_bytes_max = (0xfff9 * 4),
        .periods_min = 1,
        .periods_max = (0xfff9 / 9),
};

static const struct snd_pcm_hardware sis_capture_hw_info = {
        .info = (SNDRV_PCM_INFO_MMAP |
                 SNDRV_PCM_INFO_MMAP_VALID |
                 SNDRV_PCM_INFO_INTERLEAVED |
                 SNDRV_PCM_INFO_BLOCK_TRANSFER |
                 SNDRV_PCM_INFO_SYNC_START |
                 SNDRV_PCM_INFO_RESUME),
        .formats = (SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_U8 |
                    SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_U16_LE),
        .rates = SNDRV_PCM_RATE_48000,
        .rate_min = 4000,
        .rate_max = 48000,
        .channels_min = 1,
        .channels_max = 2,
        .buffer_bytes_max = (0xfff9 * 4),
        .period_bytes_min = 9,
        .period_bytes_max = (0xfff9 * 4),
        .periods_min = 1,
        .periods_max = (0xfff9 / 9),
};

static void sis_update_sso(struct voice *voice, u16 period)
{
        void __iomem *base = voice->ctrl_base;

        voice->sso += period;
        if (voice->sso >= voice->buffer_size)
                voice->sso -= voice->buffer_size;

        /* Enforce the documented hardware minimum offset */
        if (voice->sso < 8)
                voice->sso = 8;

        /* The SSO is in the upper 16 bits of the register. */
        writew(voice->sso & 0xffff, base + SIS_PLAY_DMA_SSO_ESO + 2);
}

static void sis_update_voice(struct voice *voice)
{
        if (voice->flags & VOICE_SSO_TIMING) {
                sis_update_sso(voice, voice->period_size);
        } else if (voice->flags & VOICE_SYNC_TIMING) {
                int sync;

                /* If we've not hit the end of the virtual period, update
                 * our records and keep going.
                 */
                if (voice->vperiod > voice->period_size) {
                        voice->vperiod -= voice->period_size;
                        if (voice->vperiod < voice->period_size)
                                sis_update_sso(voice, voice->vperiod);
                        else
                                sis_update_sso(voice, voice->period_size);
                        return;
                }

                /* Calculate our relative offset between the target and
                 * the actual CSO value. Since we're operating in a loop,
                 * if the value is more than half way around, we can
                 * consider ourselves wrapped.
                 */
                sync = voice->sync_cso;
                sync -= readw(voice->sync_base + SIS_CAPTURE_DMA_FORMAT_CSO);
                if (sync > (voice->sync_buffer_size / 2))
                        sync -= voice->sync_buffer_size;

                /* If sync is positive, then we interrupted too early, and
                 * we'll need to come back in a few samples and try again.
                 * There's a minimum wait, as it takes some time for the DMA
                 * engine to startup, etc...
                 */
                if (sync > 0) {
                        if (sync < 16)
                                sync = 16;
                        sis_update_sso(voice, sync);
                        return;
                }

                /* Ok, we interrupted right on time, or (hopefully) just
                 * a bit late. We'll adjst our next waiting period based
                 * on how close we got.
                 *
                 * We need to stay just behind the actual channel to ensure
                 * it really is past a period when we get our interrupt --
                 * otherwise we'll fall into the early code above and have
                 * a minimum wait time, which makes us quite late here,
                 * eating into the user's time to refresh the buffer, esp.
                 * if using small periods.
                 *
                 * If we're less than 9 samples behind, we're on target.
                 * Otherwise, shorten the next vperiod by the amount we've
                 * been delayed.
                 */
                if (sync > -9)
                        voice->vperiod = voice->sync_period_size + 1;
                else
                        voice->vperiod = voice->sync_period_size + sync + 10;

                if (voice->vperiod < voice->buffer_size) {
                        sis_update_sso(voice, voice->vperiod);
                        voice->vperiod = 0;
                } else
                        sis_update_sso(voice, voice->period_size);

                sync = voice->sync_cso + voice->sync_period_size;
                if (sync >= voice->sync_buffer_size)
                        sync -= voice->sync_buffer_size;
                voice->sync_cso = sync;
        }

        snd_pcm_period_elapsed(voice->substream);
}

static void sis_voice_irq(u32 status, struct voice *voice)
{
        int bit;

        while (status) {
                bit = __ffs(status);
                status >>= bit + 1;
                voice += bit;
                sis_update_voice(voice);
                voice++;
        }
}

static irqreturn_t sis_interrupt(int irq, void *dev)
{
        struct sis7019 *sis = dev;
        unsigned long io = sis->ioport;
        struct voice *voice;
        u32 intr, status;

        /* We only use the DMA interrupts, and we don't enable any other
         * source of interrupts. But, it is possible to see an interrupt
         * status that didn't actually interrupt us, so eliminate anything
         * we're not expecting to avoid falsely claiming an IRQ, and an
         * ensuing endless loop.
         */
        intr = inl(io + SIS_GISR);
        intr &= SIS_GISR_AUDIO_PLAY_DMA_IRQ_STATUS |
                SIS_GISR_AUDIO_RECORD_DMA_IRQ_STATUS;
        if (!intr)
                return IRQ_NONE;

        do {
                status = inl(io + SIS_PISR_A);
                if (status) {
                        sis_voice_irq(status, sis->voices);
                        outl(status, io + SIS_PISR_A);
                }

                status = inl(io + SIS_PISR_B);
                if (status) {
                        sis_voice_irq(status, &sis->voices[32]);
                        outl(status, io + SIS_PISR_B);
                }

                status = inl(io + SIS_RISR);
                if (status) {
                        voice = &sis->capture_voice;
                        if (!voice->timing)
                                snd_pcm_period_elapsed(voice->substream);

                        outl(status, io + SIS_RISR);
                }

                outl(intr, io + SIS_GISR);
                intr = inl(io + SIS_GISR);
                intr &= SIS_GISR_AUDIO_PLAY_DMA_IRQ_STATUS |
                        SIS_GISR_AUDIO_RECORD_DMA_IRQ_STATUS;
        } while (intr);

        return IRQ_HANDLED;
}

static u32 sis_rate_to_delta(unsigned int rate)
{
        u32 delta;

        /* This was copied from the trident driver, but it seems its gotten
         * around a bit... nevertheless, it works well.
         *
         * We special case 44100 and 8000 since rounding with the equation
         * does not give us an accurate enough value. For 11025 and 22050
         * the equation gives us the best answer. All other frequencies will
         * also use the equation. JDW
         */
        if (rate == 44100)
                delta = 0xeb3;
        else if (rate == 8000)
                delta = 0x2ab;
        else if (rate == 48000)
                delta = 0x1000;
        else
                delta = DIV_ROUND_CLOSEST(rate << 12, 48000) & 0x0000ffff;
        return delta;
}

static void __sis_map_silence(struct sis7019 *sis)
{
        /* Helper function: must hold sis->voice_lock on entry */
        if (!sis->silence_users)
                sis->silence_dma_addr = dma_map_single(&sis->pci->dev,
                                                sis->suspend_state[0],
                                                4096, DMA_TO_DEVICE);
        sis->silence_users++;
}

static void __sis_unmap_silence(struct sis7019 *sis)
{
        /* Helper function: must hold sis->voice_lock on entry */
        sis->silence_users--;
        if (!sis->silence_users)
                dma_unmap_single(&sis->pci->dev, sis->silence_dma_addr, 4096,
                                        DMA_TO_DEVICE);
}

static void sis_free_voice(struct sis7019 *sis, struct voice *voice)
{
        guard(spinlock_irqsave)(&sis->voice_lock);
        if (voice->timing) {
                __sis_unmap_silence(sis);
                voice->timing->flags &= ~(VOICE_IN_USE | VOICE_SSO_TIMING |
                                                VOICE_SYNC_TIMING);
                voice->timing = NULL;
        }
        voice->flags &= ~(VOICE_IN_USE | VOICE_SSO_TIMING | VOICE_SYNC_TIMING);
}

static struct voice *__sis_alloc_playback_voice(struct sis7019 *sis)
{
        /* Must hold the voice_lock on entry */
        struct voice *voice;
        int i;

        for (i = 0; i < 64; i++) {
                voice = &sis->voices[i];
                if (voice->flags & VOICE_IN_USE)
                        continue;
                voice->flags |= VOICE_IN_USE;
                goto found_one;
        }
        voice = NULL;

found_one:
        return voice;
}

static struct voice *sis_alloc_playback_voice(struct sis7019 *sis)
{
        guard(spinlock_irqsave)(&sis->voice_lock);
        return __sis_alloc_playback_voice(sis);
}

static int sis_alloc_timing_voice(struct snd_pcm_substream *substream,
                                        struct snd_pcm_hw_params *hw_params)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice = runtime->private_data;
        unsigned int period_size, buffer_size;
        int needed;

        /* If there are one or two periods per buffer, we don't need a
         * timing voice, as we can use the capture channel's interrupts
         * to clock out the periods.
         */
        period_size = params_period_size(hw_params);
        buffer_size = params_buffer_size(hw_params);
        needed = (period_size != buffer_size &&
                        period_size != (buffer_size / 2));

        if (needed && !voice->timing) {
                scoped_guard(spinlock_irqsave, &sis->voice_lock) {
                        voice->timing = __sis_alloc_playback_voice(sis);
                        if (voice->timing)
                                __sis_map_silence(sis);
                }
                if (!voice->timing)
                        return -ENOMEM;
                voice->timing->substream = substream;
        } else if (!needed && voice->timing) {
                sis_free_voice(sis, voice);
                voice->timing = NULL;
        }

        return 0;
}

static int sis_playback_open(struct snd_pcm_substream *substream)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice;

        voice = sis_alloc_playback_voice(sis);
        if (!voice)
                return -EAGAIN;

        voice->substream = substream;
        runtime->private_data = voice;
        runtime->hw = sis_playback_hw_info;
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
                                                9, 0xfff9);
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
                                                9, 0xfff9);
        snd_pcm_set_sync(substream);
        return 0;
}

static int sis_substream_close(struct snd_pcm_substream *substream)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice = runtime->private_data;

        sis_free_voice(sis, voice);
        return 0;
}

static int sis_pcm_playback_prepare(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice = runtime->private_data;
        void __iomem *ctrl_base = voice->ctrl_base;
        void __iomem *wave_base = voice->wave_base;
        u32 format, dma_addr, control, sso_eso, delta, reg;
        u16 leo;

        /* We rely on the PCM core to ensure that the parameters for this
         * substream do not change on us while we're programming the HW.
         */
        format = 0;
        if (snd_pcm_format_width(runtime->format) == 8)
                format |= SIS_PLAY_DMA_FORMAT_8BIT;
        if (!snd_pcm_format_signed(runtime->format))
                format |= SIS_PLAY_DMA_FORMAT_UNSIGNED;
        if (runtime->channels == 1)
                format |= SIS_PLAY_DMA_FORMAT_MONO;

        /* The baseline setup is for a single period per buffer, and
         * we add bells and whistles as needed from there.
         */
        dma_addr = runtime->dma_addr;
        leo = runtime->buffer_size - 1;
        control = leo | SIS_PLAY_DMA_LOOP | SIS_PLAY_DMA_INTR_AT_LEO;
        sso_eso = leo;

        if (runtime->period_size == (runtime->buffer_size / 2)) {
                control |= SIS_PLAY_DMA_INTR_AT_MLP;
        } else if (runtime->period_size != runtime->buffer_size) {
                voice->flags |= VOICE_SSO_TIMING;
                voice->sso = runtime->period_size - 1;
                voice->period_size = runtime->period_size;
                voice->buffer_size = runtime->buffer_size;

                control &= ~SIS_PLAY_DMA_INTR_AT_LEO;
                control |= SIS_PLAY_DMA_INTR_AT_SSO;
                sso_eso |= (runtime->period_size - 1) << 16;
        }

        delta = sis_rate_to_delta(runtime->rate);

        /* Ok, we're ready to go, set up the channel.
         */
        writel(format, ctrl_base + SIS_PLAY_DMA_FORMAT_CSO);
        writel(dma_addr, ctrl_base + SIS_PLAY_DMA_BASE);
        writel(control, ctrl_base + SIS_PLAY_DMA_CONTROL);
        writel(sso_eso, ctrl_base + SIS_PLAY_DMA_SSO_ESO);

        for (reg = 0; reg < SIS_WAVE_SIZE; reg += 4)
                writel(0, wave_base + reg);

        writel(SIS_WAVE_GENERAL_WAVE_VOLUME, wave_base + SIS_WAVE_GENERAL);
        writel(delta << 16, wave_base + SIS_WAVE_GENERAL_ARTICULATION);
        writel(SIS_WAVE_CHANNEL_CONTROL_FIRST_SAMPLE |
                        SIS_WAVE_CHANNEL_CONTROL_AMP_ENABLE |
                        SIS_WAVE_CHANNEL_CONTROL_INTERPOLATE_ENABLE,
                        wave_base + SIS_WAVE_CHANNEL_CONTROL);

        /* Force PCI writes to post. */
        readl(ctrl_base);

        return 0;
}

static int sis_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        unsigned long io = sis->ioport;
        struct snd_pcm_substream *s;
        struct voice *voice;
        void *chip;
        int starting;
        u32 record = 0;
        u32 play[2] = { 0, 0 };

        /* No locks needed, as the PCM core will hold the locks on the
         * substreams, and the HW will only start/stop the indicated voices
         * without changing the state of the others.
         */
        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
        case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
        case SNDRV_PCM_TRIGGER_RESUME:
                starting = 1;
                break;
        case SNDRV_PCM_TRIGGER_STOP:
        case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
        case SNDRV_PCM_TRIGGER_SUSPEND:
                starting = 0;
                break;
        default:
                return -EINVAL;
        }

        snd_pcm_group_for_each_entry(s, substream) {
                /* Make sure it is for us... */
                chip = snd_pcm_substream_chip(s);
                if (chip != sis)
                        continue;

                voice = s->runtime->private_data;
                if (voice->flags & VOICE_CAPTURE) {
                        record |= 1 << voice->num;
                        voice = voice->timing;
                }

                /* voice could be NULL if this a recording stream, and it
                 * doesn't have an external timing channel.
                 */
                if (voice)
                        play[voice->num / 32] |= 1 << (voice->num & 0x1f);

                snd_pcm_trigger_done(s, substream);
        }

        if (starting) {
                if (record)
                        outl(record, io + SIS_RECORD_START_REG);
                if (play[0])
                        outl(play[0], io + SIS_PLAY_START_A_REG);
                if (play[1])
                        outl(play[1], io + SIS_PLAY_START_B_REG);
        } else {
                if (record)
                        outl(record, io + SIS_RECORD_STOP_REG);
                if (play[0])
                        outl(play[0], io + SIS_PLAY_STOP_A_REG);
                if (play[1])
                        outl(play[1], io + SIS_PLAY_STOP_B_REG);
        }
        return 0;
}

static snd_pcm_uframes_t sis_pcm_pointer(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice = runtime->private_data;
        u32 cso;

        cso = readl(voice->ctrl_base + SIS_PLAY_DMA_FORMAT_CSO);
        cso &= 0xffff;
        return cso;
}

static int sis_capture_open(struct snd_pcm_substream *substream)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice = &sis->capture_voice;

        /* FIXME: The driver only supports recording from one channel
         * at the moment, but it could support more.
         */
        scoped_guard(spinlock_irqsave, &sis->voice_lock) {
                if (voice->flags & VOICE_IN_USE)
                        voice = NULL;
                else
                        voice->flags |= VOICE_IN_USE;
        }

        if (!voice)
                return -EAGAIN;

        voice->substream = substream;
        runtime->private_data = voice;
        runtime->hw = sis_capture_hw_info;
        runtime->hw.rates = sis->ac97[0]->rates[AC97_RATES_ADC];
        snd_pcm_limit_hw_rates(runtime);
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
                                                9, 0xfff9);
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
                                                9, 0xfff9);
        snd_pcm_set_sync(substream);
        return 0;
}

static int sis_capture_hw_params(struct snd_pcm_substream *substream,
                                        struct snd_pcm_hw_params *hw_params)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        int rc;

        rc = snd_ac97_set_rate(sis->ac97[0], AC97_PCM_LR_ADC_RATE,
                                                params_rate(hw_params));
        if (rc)
                goto out;

        rc = sis_alloc_timing_voice(substream, hw_params);

out:
        return rc;
}

static void sis_prepare_timing_voice(struct voice *voice,
                                        struct snd_pcm_substream *substream)
{
        struct sis7019 *sis = snd_pcm_substream_chip(substream);
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *timing = voice->timing;
        void __iomem *play_base = timing->ctrl_base;
        void __iomem *wave_base = timing->wave_base;
        u16 buffer_size, period_size;
        u32 format, control, sso_eso, delta;
        u32 vperiod, sso, reg;

        /* Set our initial buffer and period as large as we can given a
         * single page of silence.
         */
        buffer_size = 4096 / runtime->channels;
        buffer_size /= snd_pcm_format_size(runtime->format, 1);
        period_size = buffer_size;

        /* Initially, we want to interrupt just a bit behind the end of
         * the period we're clocking out. 12 samples seems to give a good
         * delay.
         *
         * We want to spread our interrupts throughout the virtual period,
         * so that we don't end up with two interrupts back to back at the
         * end -- this helps minimize the effects of any jitter. Adjust our
         * clocking period size so that the last period is at least a fourth
         * of a full period.
         *
         * This is all moot if we don't need to use virtual periods.
         */
        vperiod = runtime->period_size + 12;
        if (vperiod > period_size) {
                u16 tail = vperiod % period_size;
                u16 quarter_period = period_size / 4;

                if (tail && tail < quarter_period) {
                        u16 loops = vperiod / period_size;

                        tail = quarter_period - tail;
                        tail += loops - 1;
                        tail /= loops;
                        period_size -= tail;
                }

                sso = period_size - 1;
        } else {
                /* The initial period will fit inside the buffer, so we
                 * don't need to use virtual periods -- disable them.
                 */
                period_size = runtime->period_size;
                sso = vperiod - 1;
                vperiod = 0;
        }

        /* The interrupt handler implements the timing synchronization, so
         * setup its state.
         */
        timing->flags |= VOICE_SYNC_TIMING;
        timing->sync_base = voice->ctrl_base;
        timing->sync_cso = runtime->period_size;
        timing->sync_period_size = runtime->period_size;
        timing->sync_buffer_size = runtime->buffer_size;
        timing->period_size = period_size;
        timing->buffer_size = buffer_size;
        timing->sso = sso;
        timing->vperiod = vperiod;

        /* Using unsigned samples with the all-zero silence buffer
         * forces the output to the lower rail, killing playback.
         * So ignore unsigned vs signed -- it doesn't change the timing.
         */
        format = 0;
        if (snd_pcm_format_width(runtime->format) == 8)
                format = SIS_CAPTURE_DMA_FORMAT_8BIT;
        if (runtime->channels == 1)
                format |= SIS_CAPTURE_DMA_FORMAT_MONO;

        control = timing->buffer_size - 1;
        control |= SIS_PLAY_DMA_LOOP | SIS_PLAY_DMA_INTR_AT_SSO;
        sso_eso = timing->buffer_size - 1;
        sso_eso |= timing->sso << 16;

        delta = sis_rate_to_delta(runtime->rate);

        /* We've done the math, now configure the channel.
         */
        writel(format, play_base + SIS_PLAY_DMA_FORMAT_CSO);
        writel(sis->silence_dma_addr, play_base + SIS_PLAY_DMA_BASE);
        writel(control, play_base + SIS_PLAY_DMA_CONTROL);
        writel(sso_eso, play_base + SIS_PLAY_DMA_SSO_ESO);

        for (reg = 0; reg < SIS_WAVE_SIZE; reg += 4)
                writel(0, wave_base + reg);

        writel(SIS_WAVE_GENERAL_WAVE_VOLUME, wave_base + SIS_WAVE_GENERAL);
        writel(delta << 16, wave_base + SIS_WAVE_GENERAL_ARTICULATION);
        writel(SIS_WAVE_CHANNEL_CONTROL_FIRST_SAMPLE |
                        SIS_WAVE_CHANNEL_CONTROL_AMP_ENABLE |
                        SIS_WAVE_CHANNEL_CONTROL_INTERPOLATE_ENABLE,
                        wave_base + SIS_WAVE_CHANNEL_CONTROL);
}

static int sis_pcm_capture_prepare(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct voice *voice = runtime->private_data;
        void __iomem *rec_base = voice->ctrl_base;
        u32 format, dma_addr, control;
        u16 leo;

        /* We rely on the PCM core to ensure that the parameters for this
         * substream do not change on us while we're programming the HW.
         */
        format = 0;
        if (snd_pcm_format_width(runtime->format) == 8)
                format = SIS_CAPTURE_DMA_FORMAT_8BIT;
        if (!snd_pcm_format_signed(runtime->format))
                format |= SIS_CAPTURE_DMA_FORMAT_UNSIGNED;
        if (runtime->channels == 1)
                format |= SIS_CAPTURE_DMA_FORMAT_MONO;

        dma_addr = runtime->dma_addr;
        leo = runtime->buffer_size - 1;
        control = leo | SIS_CAPTURE_DMA_LOOP;

        /* If we've got more than two periods per buffer, then we have
         * use a timing voice to clock out the periods. Otherwise, we can
         * use the capture channel's interrupts.
         */
        if (voice->timing) {
                sis_prepare_timing_voice(voice, substream);
        } else {
                control |= SIS_CAPTURE_DMA_INTR_AT_LEO;
                if (runtime->period_size != runtime->buffer_size)
                        control |= SIS_CAPTURE_DMA_INTR_AT_MLP;
        }

        writel(format, rec_base + SIS_CAPTURE_DMA_FORMAT_CSO);
        writel(dma_addr, rec_base + SIS_CAPTURE_DMA_BASE);
        writel(control, rec_base + SIS_CAPTURE_DMA_CONTROL);

        /* Force the writes to post. */
        readl(rec_base);

        return 0;
}

static const struct snd_pcm_ops sis_playback_ops = {
        .open = sis_playback_open,
        .close = sis_substream_close,
        .prepare = sis_pcm_playback_prepare,
        .trigger = sis_pcm_trigger,
        .pointer = sis_pcm_pointer,
};

static const struct snd_pcm_ops sis_capture_ops = {
        .open = sis_capture_open,
        .close = sis_substream_close,
        .hw_params = sis_capture_hw_params,
        .prepare = sis_pcm_capture_prepare,
        .trigger = sis_pcm_trigger,
        .pointer = sis_pcm_pointer,
};

static int sis_pcm_create(struct sis7019 *sis)
{
        struct snd_pcm *pcm;
        int rc;

        /* We have 64 voices, and the driver currently records from
         * only one channel, though that could change in the future.
         */
        rc = snd_pcm_new(sis->card, "SiS7019", 0, 64, 1, &pcm);
        if (rc)
                return rc;

        pcm->private_data = sis;
        strscpy(pcm->name, "SiS7019");
        sis->pcm = pcm;

        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &sis_playback_ops);
        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &sis_capture_ops);

        /* Try to preallocate some memory, but it's not the end of the
         * world if this fails.
         */
        snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_DEV,
                                       &sis->pci->dev, 64*1024, 128*1024);

        return 0;
}

static unsigned short sis_ac97_rw(struct sis7019 *sis, int codec, u32 cmd)
{
        unsigned long io = sis->ioport;
        unsigned short val = 0xffff;
        u16 status;
        u16 rdy;
        int count;
        static const u16 codec_ready[3] = {
                SIS_AC97_STATUS_CODEC_READY,
                SIS_AC97_STATUS_CODEC2_READY,
                SIS_AC97_STATUS_CODEC3_READY,
        };

        rdy = codec_ready[codec];


        /* Get the AC97 semaphore -- software first, so we don't spin
         * pounding out IO reads on the hardware semaphore...
         */
        guard(mutex)(&sis->ac97_mutex);

        count = 0xffff;
        while ((inw(io + SIS_AC97_SEMA) & SIS_AC97_SEMA_BUSY) && --count)
                udelay(1);

        if (!count)
                goto timeout;

        /* ... and wait for any outstanding commands to complete ...
         */
        count = 0xffff;
        do {
                status = inw(io + SIS_AC97_STATUS);
                if ((status & rdy) && !(status & SIS_AC97_STATUS_BUSY))
                        break;

                udelay(1);
        } while (--count);

        if (!count)
                goto timeout_sema;

        /* ... before sending our command and waiting for it to finish ...
         */
        outl(cmd, io + SIS_AC97_CMD);
        udelay(10);

        count = 0xffff;
        while ((inw(io + SIS_AC97_STATUS) & SIS_AC97_STATUS_BUSY) && --count)
                udelay(1);

        /* ... and reading the results (if any).
         */
        val = inl(io + SIS_AC97_CMD) >> 16;

timeout_sema:
        outl(SIS_AC97_SEMA_RELEASE, io + SIS_AC97_SEMA);
timeout:
        if (!count) {
                dev_err(&sis->pci->dev, "ac97 codec %d timeout cmd 0x%08x\n",
                                        codec, cmd);
        }

        return val;
}

static void sis_ac97_write(struct snd_ac97 *ac97, unsigned short reg,
                                unsigned short val)
{
        static const u32 cmd[3] = {
                SIS_AC97_CMD_CODEC_WRITE,
                SIS_AC97_CMD_CODEC2_WRITE,
                SIS_AC97_CMD_CODEC3_WRITE,
        };
        sis_ac97_rw(ac97->private_data, ac97->num,
                        (val << 16) | (reg << 8) | cmd[ac97->num]);
}

static unsigned short sis_ac97_read(struct snd_ac97 *ac97, unsigned short reg)
{
        static const u32 cmd[3] = {
                SIS_AC97_CMD_CODEC_READ,
                SIS_AC97_CMD_CODEC2_READ,
                SIS_AC97_CMD_CODEC3_READ,
        };
        return sis_ac97_rw(ac97->private_data, ac97->num,
                                        (reg << 8) | cmd[ac97->num]);
}

static int sis_mixer_create(struct sis7019 *sis)
{
        struct snd_ac97_bus *bus;
        struct snd_ac97_template ac97;
        static const struct snd_ac97_bus_ops ops = {
                .write = sis_ac97_write,
                .read = sis_ac97_read,
        };
        int rc;

        memset(&ac97, 0, sizeof(ac97));
        ac97.private_data = sis;

        rc = snd_ac97_bus(sis->card, 0, &ops, NULL, &bus);
        if (!rc && sis->codecs_present & SIS_PRIMARY_CODEC_PRESENT)
                rc = snd_ac97_mixer(bus, &ac97, &sis->ac97[0]);
        ac97.num = 1;
        if (!rc && (sis->codecs_present & SIS_SECONDARY_CODEC_PRESENT))
                rc = snd_ac97_mixer(bus, &ac97, &sis->ac97[1]);
        ac97.num = 2;
        if (!rc && (sis->codecs_present & SIS_TERTIARY_CODEC_PRESENT))
                rc = snd_ac97_mixer(bus, &ac97, &sis->ac97[2]);

        /* If we return an error here, then snd_card_free() should
         * free up any ac97 codecs that got created, as well as the bus.
         */
        return rc;
}

static void sis_chip_free(struct snd_card *card)
{
        struct sis7019 *sis = card->private_data;

        /* Reset the chip, and disable all interrputs.
         */
        outl(SIS_GCR_SOFTWARE_RESET, sis->ioport + SIS_GCR);
        udelay(25);
        outl(0, sis->ioport + SIS_GCR);
        outl(0, sis->ioport + SIS_GIER);

        /* Now, free everything we allocated.
         */
        if (sis->irq >= 0)
                free_irq(sis->irq, sis);
}

static int sis_chip_init(struct sis7019 *sis)
{
        unsigned long io = sis->ioport;
        void __iomem *ioaddr = sis->ioaddr;
        unsigned long timeout;
        u16 status;
        int count;
        int i;

        /* Reset the audio controller
         */
        outl(SIS_GCR_SOFTWARE_RESET, io + SIS_GCR);
        udelay(25);
        outl(0, io + SIS_GCR);

        /* Get the AC-link semaphore, and reset the codecs
         */
        count = 0xffff;
        while ((inw(io + SIS_AC97_SEMA) & SIS_AC97_SEMA_BUSY) && --count)
                udelay(1);

        if (!count)
                return -EIO;

        outl(SIS_AC97_CMD_CODEC_COLD_RESET, io + SIS_AC97_CMD);
        udelay(250);

        count = 0xffff;
        while ((inw(io + SIS_AC97_STATUS) & SIS_AC97_STATUS_BUSY) && --count)
                udelay(1);

        /* Command complete, we can let go of the semaphore now.
         */
        outl(SIS_AC97_SEMA_RELEASE, io + SIS_AC97_SEMA);
        if (!count)
                return -EIO;

        /* Now that we've finished the reset, find out what's attached.
         * There are some codec/board combinations that take an extremely
         * long time to come up. 350+ ms has been observed in the field,
         * so we'll give them up to 500ms.
         */
        sis->codecs_present = 0;
        timeout = msecs_to_jiffies(500) + jiffies;
        while (time_before_eq(jiffies, timeout)) {
                status = inl(io + SIS_AC97_STATUS);
                if (status & SIS_AC97_STATUS_CODEC_READY)
                        sis->codecs_present |= SIS_PRIMARY_CODEC_PRESENT;
                if (status & SIS_AC97_STATUS_CODEC2_READY)
                        sis->codecs_present |= SIS_SECONDARY_CODEC_PRESENT;
                if (status & SIS_AC97_STATUS_CODEC3_READY)
                        sis->codecs_present |= SIS_TERTIARY_CODEC_PRESENT;

                if (sis->codecs_present == codecs)
                        break;

                msleep(1);
        }

        /* All done, check for errors.
         */
        if (!sis->codecs_present) {
                dev_err(&sis->pci->dev, "could not find any codecs\n");
                return -EIO;
        }

        if (sis->codecs_present != codecs) {
                dev_warn(&sis->pci->dev, "missing codecs, found %0x, expected %0x\n",
                                         sis->codecs_present, codecs);
        }

        /* Let the hardware know that the audio driver is alive,
         * and enable PCM slots on the AC-link for L/R playback (3 & 4) and
         * record channels. We're going to want to use Variable Rate Audio
         * for recording, to avoid needlessly resampling from 48kHZ.
         */
        outl(SIS_AC97_CONF_AUDIO_ALIVE, io + SIS_AC97_CONF);
        outl(SIS_AC97_CONF_AUDIO_ALIVE | SIS_AC97_CONF_PCM_LR_ENABLE |
                SIS_AC97_CONF_PCM_CAP_MIC_ENABLE |
                SIS_AC97_CONF_PCM_CAP_LR_ENABLE |
                SIS_AC97_CONF_CODEC_VRA_ENABLE, io + SIS_AC97_CONF);

        /* All AC97 PCM slots should be sourced from sub-mixer 0.
         */
        outl(0, io + SIS_AC97_PSR);

        /* There is only one valid DMA setup for a PCI environment.
         */
        outl(SIS_DMA_CSR_PCI_SETTINGS, io + SIS_DMA_CSR);

        /* Reset the synchronization groups for all of the channels
         * to be asynchronous. If we start doing SPDIF or 5.1 sound, etc.
         * we'll need to change how we handle these. Until then, we just
         * assign sub-mixer 0 to all playback channels, and avoid any
         * attenuation on the audio.
         */
        outl(0, io + SIS_PLAY_SYNC_GROUP_A);
        outl(0, io + SIS_PLAY_SYNC_GROUP_B);
        outl(0, io + SIS_PLAY_SYNC_GROUP_C);
        outl(0, io + SIS_PLAY_SYNC_GROUP_D);
        outl(0, io + SIS_MIXER_SYNC_GROUP);

        for (i = 0; i < 64; i++) {
                writel(i, SIS_MIXER_START_ADDR(ioaddr, i));
                writel(SIS_MIXER_RIGHT_NO_ATTEN | SIS_MIXER_LEFT_NO_ATTEN |
                                SIS_MIXER_DEST_0, SIS_MIXER_ADDR(ioaddr, i));
        }

        /* Don't attenuate any audio set for the wave amplifier.
         *
         * FIXME: Maximum attenuation is set for the music amp, which will
         * need to change if we start using the synth engine.
         */
        outl(0xffff0000, io + SIS_WEVCR);

        /* Ensure that the wave engine is in normal operating mode.
         */
        outl(0, io + SIS_WECCR);

        /* Go ahead and enable the DMA interrupts. They won't go live
         * until we start a channel.
         */
        outl(SIS_GIER_AUDIO_PLAY_DMA_IRQ_ENABLE |
                SIS_GIER_AUDIO_RECORD_DMA_IRQ_ENABLE, io + SIS_GIER);

        return 0;
}

static int sis_suspend(struct device *dev)
{
        struct snd_card *card = dev_get_drvdata(dev);
        struct sis7019 *sis = card->private_data;
        void __iomem *ioaddr = sis->ioaddr;
        int i;

        snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
        if (sis->codecs_present & SIS_PRIMARY_CODEC_PRESENT)
                snd_ac97_suspend(sis->ac97[0]);
        if (sis->codecs_present & SIS_SECONDARY_CODEC_PRESENT)
                snd_ac97_suspend(sis->ac97[1]);
        if (sis->codecs_present & SIS_TERTIARY_CODEC_PRESENT)
                snd_ac97_suspend(sis->ac97[2]);

        /* snd_pcm_suspend_all() stopped all channels, so we're quiescent.
         */
        if (sis->irq >= 0) {
                free_irq(sis->irq, sis);
                sis->irq = -1;
        }

        /* Save the internal state away
         */
        for (i = 0; i < 4; i++) {
                memcpy_fromio(sis->suspend_state[i], ioaddr, 4096);
                ioaddr += 4096;
        }

        return 0;
}

static int sis_resume(struct device *dev)
{
        struct pci_dev *pci = to_pci_dev(dev);
        struct snd_card *card = dev_get_drvdata(dev);
        struct sis7019 *sis = card->private_data;
        void __iomem *ioaddr = sis->ioaddr;
        int i;

        if (sis_chip_init(sis)) {
                dev_err(&pci->dev, "unable to re-init controller\n");
                goto error;
        }

        if (request_irq(pci->irq, sis_interrupt, IRQF_SHARED,
                        KBUILD_MODNAME, sis)) {
                dev_err(&pci->dev, "unable to regain IRQ %d\n", pci->irq);
                goto error;
        }

        /* Restore saved state, then clear out the page we use for the
         * silence buffer.
         */
        for (i = 0; i < 4; i++) {
                memcpy_toio(ioaddr, sis->suspend_state[i], 4096);
                ioaddr += 4096;
        }

        memset(sis->suspend_state[0], 0, 4096);

        sis->irq = pci->irq;

        if (sis->codecs_present & SIS_PRIMARY_CODEC_PRESENT)
                snd_ac97_resume(sis->ac97[0]);
        if (sis->codecs_present & SIS_SECONDARY_CODEC_PRESENT)
                snd_ac97_resume(sis->ac97[1]);
        if (sis->codecs_present & SIS_TERTIARY_CODEC_PRESENT)
                snd_ac97_resume(sis->ac97[2]);

        snd_power_change_state(card, SNDRV_CTL_POWER_D0);
        return 0;

error:
        snd_card_disconnect(card);
        return -EIO;
}

static DEFINE_SIMPLE_DEV_PM_OPS(sis_pm, sis_suspend, sis_resume);

static int sis_alloc_suspend(struct sis7019 *sis)
{
        int i;

        /* We need 16K to store the internal wave engine state during a
         * suspend, but we don't need it to be contiguous, so play nice
         * with the memory system. We'll also use this area for a silence
         * buffer.
         */
        for (i = 0; i < SIS_SUSPEND_PAGES; i++) {
                sis->suspend_state[i] = devm_kmalloc(&sis->pci->dev, 4096,
                                                     GFP_KERNEL);
                if (!sis->suspend_state[i])
                        return -ENOMEM;
        }
        memset(sis->suspend_state[0], 0, 4096);

        return 0;
}

static int sis_chip_create(struct snd_card *card,
                           struct pci_dev *pci)
{
        struct sis7019 *sis = card->private_data;
        struct voice *voice;
        int rc;
        int i;

        rc = pcim_enable_device(pci);
        if (rc)
                return rc;

        rc = dma_set_mask(&pci->dev, DMA_BIT_MASK(30));
        if (rc < 0) {
                dev_err(&pci->dev, "architecture does not support 30-bit PCI busmaster DMA");
                return -ENXIO;
        }

        mutex_init(&sis->ac97_mutex);
        spin_lock_init(&sis->voice_lock);
        sis->card = card;
        sis->pci = pci;
        sis->irq = -1;
        sis->ioport = pci_resource_start(pci, 0);

        rc = pcim_request_all_regions(pci, "SiS7019");
        if (rc) {
                dev_err(&pci->dev, "unable request regions\n");
                return rc;
        }

        sis->ioaddr = devm_ioremap(&pci->dev, pci_resource_start(pci, 1), 0x4000);
        if (!sis->ioaddr) {
                dev_err(&pci->dev, "unable to remap MMIO, aborting\n");
                return -EIO;
        }

        rc = sis_alloc_suspend(sis);
        if (rc < 0) {
                dev_err(&pci->dev, "unable to allocate state storage\n");
                return rc;
        }

        rc = sis_chip_init(sis);
        if (rc)
                return rc;
        card->private_free = sis_chip_free;

        rc = request_irq(pci->irq, sis_interrupt, IRQF_SHARED, KBUILD_MODNAME,
                         sis);
        if (rc) {
                dev_err(&pci->dev, "unable to allocate irq %d\n", sis->irq);
                return rc;
        }

        sis->irq = pci->irq;
        card->sync_irq = sis->irq;
        pci_set_master(pci);

        for (i = 0; i < 64; i++) {
                voice = &sis->voices[i];
                voice->num = i;
                voice->ctrl_base = SIS_PLAY_DMA_ADDR(sis->ioaddr, i);
                voice->wave_base = SIS_WAVE_ADDR(sis->ioaddr, i);
        }

        voice = &sis->capture_voice;
        voice->flags = VOICE_CAPTURE;
        voice->num = SIS_CAPTURE_CHAN_AC97_PCM_IN;
        voice->ctrl_base = SIS_CAPTURE_DMA_ADDR(sis->ioaddr, voice->num);

        return 0;
}

static int __snd_sis7019_probe(struct pci_dev *pci,
                               const struct pci_device_id *pci_id)
{
        struct snd_card *card;
        struct sis7019 *sis;
        int rc;

        if (!enable)
                return -ENOENT;

        /* The user can specify which codecs should be present so that we
         * can wait for them to show up if they are slow to recover from
         * the AC97 cold reset. We default to a single codec, the primary.
         *
         * We assume that SIS_PRIMARY_*_PRESENT matches bits 0-2.
         */
        codecs &= SIS_PRIMARY_CODEC_PRESENT | SIS_SECONDARY_CODEC_PRESENT |
                  SIS_TERTIARY_CODEC_PRESENT;
        if (!codecs)
                codecs = SIS_PRIMARY_CODEC_PRESENT;

        rc = snd_devm_card_new(&pci->dev, index, id, THIS_MODULE,
                               sizeof(*sis), &card);
        if (rc < 0)
                return rc;

        strscpy(card->driver, "SiS7019");
        strscpy(card->shortname, "SiS7019");
        rc = sis_chip_create(card, pci);
        if (rc)
                return rc;

        sis = card->private_data;

        rc = sis_mixer_create(sis);
        if (rc)
                return rc;

        rc = sis_pcm_create(sis);
        if (rc)
                return rc;

        snprintf(card->longname, sizeof(card->longname),
                        "%s Audio Accelerator with %s at 0x%lx, irq %d",
                        card->shortname, snd_ac97_get_short_name(sis->ac97[0]),
                        sis->ioport, sis->irq);

        rc = snd_card_register(card);
        if (rc)
                return rc;

        pci_set_drvdata(pci, card);
        return 0;
}

static int snd_sis7019_probe(struct pci_dev *pci,
                             const struct pci_device_id *pci_id)
{
        return snd_card_free_on_error(&pci->dev, __snd_sis7019_probe(pci, pci_id));
}

static struct pci_driver sis7019_driver = {
        .name = KBUILD_MODNAME,
        .id_table = snd_sis7019_ids,
        .probe = snd_sis7019_probe,
        .driver = {
                .pm = &sis_pm,
        },
};

module_pci_driver(sis7019_driver);