// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 *  Routines for control of MPU-401 in UART mode
 *
 *  MPU-401 supports UART mode which is not capable generate transmit
 *  interrupts thus output is done via polling. Without interrupt,
 *  input is done also via polling. Do not expect good performance.
 *
 *   13-03-2003:
 *      Added support for different kind of hardware I/O. Build in choices
 *      are port and mmio. For other kind of I/O, set mpu->read and
 *      mpu->write to your own I/O functions.
 */

#include <linux/io.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <sound/core.h>
#include <sound/mpu401.h>

MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
MODULE_DESCRIPTION("Routines for control of MPU-401 in UART mode");
MODULE_LICENSE("GPL");

static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu);
static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu);

/*

 */

#define snd_mpu401_input_avail(mpu) \
        (!(mpu->read(mpu, MPU401C(mpu)) & MPU401_RX_EMPTY))
#define snd_mpu401_output_ready(mpu) \
        (!(mpu->read(mpu, MPU401C(mpu)) & MPU401_TX_FULL))

/* Build in lowlevel io */
static void mpu401_write_port(struct snd_mpu401 *mpu, unsigned char data,
                              unsigned long addr)
{
        outb(data, addr);
}

static unsigned char mpu401_read_port(struct snd_mpu401 *mpu,
                                      unsigned long addr)
{
        return inb(addr);
}

static void mpu401_write_mmio(struct snd_mpu401 *mpu, unsigned char data,
                              unsigned long addr)
{
        writeb(data, (void __iomem *)addr);
}

static unsigned char mpu401_read_mmio(struct snd_mpu401 *mpu,
                                      unsigned long addr)
{
        return readb((void __iomem *)addr);
}
/*  */

static void snd_mpu401_uart_clear_rx(struct snd_mpu401 *mpu)
{
        int timeout = 100000;
        for (; timeout > 0 && snd_mpu401_input_avail(mpu); timeout--)
                mpu->read(mpu, MPU401D(mpu));
#ifdef CONFIG_SND_DEBUG
        if (timeout <= 0)
                dev_err(mpu->rmidi->dev,
                        "cmd: clear rx timeout (status = 0x%x)\n",
                        mpu->read(mpu, MPU401C(mpu)));
#endif
}

static void uart_interrupt_tx(struct snd_mpu401 *mpu)
{
        if (test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode) &&
            test_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode)) {
                guard(spinlock_irqsave)(&mpu->output_lock);
                snd_mpu401_uart_output_write(mpu);
        }
}

static void _snd_mpu401_uart_interrupt(struct snd_mpu401 *mpu)
{
        if (mpu->info_flags & MPU401_INFO_INPUT) {
                guard(spinlock_irqsave)(&mpu->input_lock);
                if (test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
                        snd_mpu401_uart_input_read(mpu);
                else
                        snd_mpu401_uart_clear_rx(mpu);
        }
        if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
                /* ok. for better Tx performance try do some output
                   when input is done */
                uart_interrupt_tx(mpu);
}

/**
 * snd_mpu401_uart_interrupt - generic MPU401-UART interrupt handler
 * @irq: the irq number
 * @dev_id: mpu401 instance
 *
 * Processes the interrupt for MPU401-UART i/o.
 *
 * Return: %IRQ_HANDLED if the interrupt was handled. %IRQ_NONE otherwise.
 */
irqreturn_t snd_mpu401_uart_interrupt(int irq, void *dev_id)
{
        struct snd_mpu401 *mpu = dev_id;
        
        if (!mpu)
                return IRQ_NONE;
        _snd_mpu401_uart_interrupt(mpu);
        return IRQ_HANDLED;
}

EXPORT_SYMBOL(snd_mpu401_uart_interrupt);

/**
 * snd_mpu401_uart_interrupt_tx - generic MPU401-UART transmit irq handler
 * @irq: the irq number
 * @dev_id: mpu401 instance
 *
 * Processes the interrupt for MPU401-UART output.
 *
 * Return: %IRQ_HANDLED if the interrupt was handled. %IRQ_NONE otherwise.
 */
irqreturn_t snd_mpu401_uart_interrupt_tx(int irq, void *dev_id)
{
        struct snd_mpu401 *mpu = dev_id;
        
        if (!mpu)
                return IRQ_NONE;
        uart_interrupt_tx(mpu);
        return IRQ_HANDLED;
}

EXPORT_SYMBOL(snd_mpu401_uart_interrupt_tx);

/*
 * timer callback
 * reprogram the timer and call the interrupt job
 */
static void snd_mpu401_uart_timer(struct timer_list *t)
{
        struct snd_mpu401 *mpu = timer_container_of(mpu, t, timer);

        scoped_guard(spinlock_irqsave, &mpu->timer_lock) {
                /*mpu->mode |= MPU401_MODE_TIMER;*/
                mod_timer(&mpu->timer,  1 + jiffies);
        }
        if (mpu->rmidi)
                _snd_mpu401_uart_interrupt(mpu);
}

/*
 * initialize the timer callback if not programmed yet
 */
static void snd_mpu401_uart_add_timer (struct snd_mpu401 *mpu, int input)
{
        guard(spinlock_irqsave)(&mpu->timer_lock);
        if (mpu->timer_invoked == 0) {
                timer_setup(&mpu->timer, snd_mpu401_uart_timer, 0);
                mod_timer(&mpu->timer, 1 + jiffies);
        } 
        mpu->timer_invoked |= input ? MPU401_MODE_INPUT_TIMER :
                MPU401_MODE_OUTPUT_TIMER;
}

/*
 * remove the timer callback if still active
 */
static void snd_mpu401_uart_remove_timer (struct snd_mpu401 *mpu, int input)
{
        guard(spinlock_irqsave)(&mpu->timer_lock);
        if (mpu->timer_invoked) {
                mpu->timer_invoked &= input ? ~MPU401_MODE_INPUT_TIMER :
                        ~MPU401_MODE_OUTPUT_TIMER;
                if (! mpu->timer_invoked)
                        timer_delete(&mpu->timer);
        }
}

/*
 * send a UART command
 * return zero if successful, non-zero for some errors
 */

static int snd_mpu401_uart_cmd(struct snd_mpu401 * mpu, unsigned char cmd,
                               int ack)
{
        int timeout, ok;

        guard(spinlock_irqsave)(&mpu->input_lock);
        if (mpu->hardware != MPU401_HW_TRID4DWAVE) {
                mpu->write(mpu, 0x00, MPU401D(mpu));
                /*snd_mpu401_uart_clear_rx(mpu);*/
        }
        /* ok. standard MPU-401 initialization */
        if (mpu->hardware != MPU401_HW_SB) {
                for (timeout = 1000; timeout > 0 &&
                             !snd_mpu401_output_ready(mpu); timeout--)
                        udelay(10);
#ifdef CONFIG_SND_DEBUG
                if (!timeout)
                        dev_err(mpu->rmidi->dev,
                                "cmd: tx timeout (status = 0x%x)\n",
                                mpu->read(mpu, MPU401C(mpu)));
#endif
        }
        mpu->write(mpu, cmd, MPU401C(mpu));
        if (ack && !(mpu->info_flags & MPU401_INFO_NO_ACK)) {
                ok = 0;
                timeout = 10000;
                while (!ok && timeout-- > 0) {
                        if (snd_mpu401_input_avail(mpu)) {
                                if (mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
                                        ok = 1;
                        }
                }
                if (!ok && mpu->read(mpu, MPU401D(mpu)) == MPU401_ACK)
                        ok = 1;
        } else
                ok = 1;
        if (!ok) {
                dev_err(mpu->rmidi->dev,
                        "cmd: 0x%x failed at 0x%lx (status = 0x%x, data = 0x%x)\n",
                        cmd, mpu->port,
                        mpu->read(mpu, MPU401C(mpu)),
                        mpu->read(mpu, MPU401D(mpu)));
                return 1;
        }
        return 0;
}

static int snd_mpu401_do_reset(struct snd_mpu401 *mpu)
{
        if (snd_mpu401_uart_cmd(mpu, MPU401_RESET, 1))
                return -EIO;
        if (snd_mpu401_uart_cmd(mpu, MPU401_ENTER_UART, 0))
                return -EIO;
        return 0;
}

/*
 * input/output open/close - protected by open_mutex in rawmidi.c
 */
static int snd_mpu401_uart_input_open(struct snd_rawmidi_substream *substream)
{
        struct snd_mpu401 *mpu;
        int err;

        mpu = substream->rmidi->private_data;
        if (mpu->open_input) {
                err = mpu->open_input(mpu);
                if (err < 0)
                        return err;
        }
        if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode)) {
                if (snd_mpu401_do_reset(mpu) < 0)
                        goto error_out;
        }
        mpu->substream_input = substream;
        set_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
        return 0;

error_out:
        if (mpu->open_input && mpu->close_input)
                mpu->close_input(mpu);
        return -EIO;
}

static int snd_mpu401_uart_output_open(struct snd_rawmidi_substream *substream)
{
        struct snd_mpu401 *mpu;
        int err;

        mpu = substream->rmidi->private_data;
        if (mpu->open_output) {
                err = mpu->open_output(mpu);
                if (err < 0)
                        return err;
        }
        if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode)) {
                if (snd_mpu401_do_reset(mpu) < 0)
                        goto error_out;
        }
        mpu->substream_output = substream;
        set_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
        return 0;

error_out:
        if (mpu->open_output && mpu->close_output)
                mpu->close_output(mpu);
        return -EIO;
}

static int snd_mpu401_uart_input_close(struct snd_rawmidi_substream *substream)
{
        struct snd_mpu401 *mpu;
        int err = 0;

        mpu = substream->rmidi->private_data;
        clear_bit(MPU401_MODE_BIT_INPUT, &mpu->mode);
        mpu->substream_input = NULL;
        if (! test_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode))
                err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
        if (mpu->close_input)
                mpu->close_input(mpu);
        if (err)
                return -EIO;
        return 0;
}

static int snd_mpu401_uart_output_close(struct snd_rawmidi_substream *substream)
{
        struct snd_mpu401 *mpu;
        int err = 0;

        mpu = substream->rmidi->private_data;
        clear_bit(MPU401_MODE_BIT_OUTPUT, &mpu->mode);
        mpu->substream_output = NULL;
        if (! test_bit(MPU401_MODE_BIT_INPUT, &mpu->mode))
                err = snd_mpu401_uart_cmd(mpu, MPU401_RESET, 0);
        if (mpu->close_output)
                mpu->close_output(mpu);
        if (err)
                return -EIO;
        return 0;
}

/*
 * trigger input callback
 */
static void
snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
{
        struct snd_mpu401 *mpu;
        int max = 64;

        mpu = substream->rmidi->private_data;
        if (up) {
                if (! test_and_set_bit(MPU401_MODE_BIT_INPUT_TRIGGER,
                                       &mpu->mode)) {
                        /* first time - flush FIFO */
                        while (max-- > 0)
                                mpu->read(mpu, MPU401D(mpu));
                        if (mpu->info_flags & MPU401_INFO_USE_TIMER)
                                snd_mpu401_uart_add_timer(mpu, 1);
                }
                
                /* read data in advance */
                guard(spinlock_irqsave)(&mpu->input_lock);
                snd_mpu401_uart_input_read(mpu);
        } else {
                if (mpu->info_flags & MPU401_INFO_USE_TIMER)
                        snd_mpu401_uart_remove_timer(mpu, 1);
                clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
        }

}

/*
 * transfer input pending data
 * call with input_lock spinlock held
 */
static void snd_mpu401_uart_input_read(struct snd_mpu401 * mpu)
{
        int max = 128;
        unsigned char byte;

        while (max-- > 0) {
                if (! snd_mpu401_input_avail(mpu))
                        break; /* input not available */
                byte = mpu->read(mpu, MPU401D(mpu));
                if (test_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
                        snd_rawmidi_receive(mpu->substream_input, &byte, 1);
        }
}

/*
 *  Tx FIFO sizes:
 *    CS4237B                   - 16 bytes
 *    AudioDrive ES1688         - 12 bytes
 *    S3 SonicVibes             -  8 bytes
 *    SoundBlaster AWE 64       -  2 bytes (ugly hardware)
 */

/*
 * write output pending bytes
 * call with output_lock spinlock held
 */
static void snd_mpu401_uart_output_write(struct snd_mpu401 * mpu)
{
        unsigned char byte;
        int max = 256;

        do {
                if (snd_rawmidi_transmit_peek(mpu->substream_output,
                                              &byte, 1) == 1) {
                        /*
                         * Try twice because there is hardware that insists on
                         * setting the output busy bit after each write.
                         */
                        if (!snd_mpu401_output_ready(mpu) &&
                            !snd_mpu401_output_ready(mpu))
                                break;  /* Tx FIFO full - try again later */
                        mpu->write(mpu, byte, MPU401D(mpu));
                        snd_rawmidi_transmit_ack(mpu->substream_output, 1);
                } else {
                        snd_mpu401_uart_remove_timer (mpu, 0);
                        break;  /* no other data - leave the tx loop */
                }
        } while (--max > 0);
}

/*
 * output trigger callback
 */
static void
snd_mpu401_uart_output_trigger(struct snd_rawmidi_substream *substream, int up)
{
        struct snd_mpu401 *mpu;

        mpu = substream->rmidi->private_data;
        if (up) {
                set_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);

                /* try to add the timer at each output trigger,
                 * since the output timer might have been removed in
                 * snd_mpu401_uart_output_write().
                 */
                if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
                        snd_mpu401_uart_add_timer(mpu, 0);

                /* output pending data */
                guard(spinlock_irqsave)(&mpu->output_lock);
                snd_mpu401_uart_output_write(mpu);
        } else {
                if (! (mpu->info_flags & MPU401_INFO_TX_IRQ))
                        snd_mpu401_uart_remove_timer(mpu, 0);
                clear_bit(MPU401_MODE_BIT_OUTPUT_TRIGGER, &mpu->mode);
        }
}

/*

 */

static const struct snd_rawmidi_ops snd_mpu401_uart_output =
{
        .open =         snd_mpu401_uart_output_open,
        .close =        snd_mpu401_uart_output_close,
        .trigger =      snd_mpu401_uart_output_trigger,
};

static const struct snd_rawmidi_ops snd_mpu401_uart_input =
{
        .open =         snd_mpu401_uart_input_open,
        .close =        snd_mpu401_uart_input_close,
        .trigger =      snd_mpu401_uart_input_trigger,
};

static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
{
        struct snd_mpu401 *mpu = rmidi->private_data;
        if (mpu->irq >= 0)
                free_irq(mpu->irq, (void *) mpu);
        release_and_free_resource(mpu->res);
        kfree(mpu);
}

/**
 * snd_mpu401_uart_new - create an MPU401-UART instance
 * @card: the card instance
 * @device: the device index, zero-based
 * @hardware: the hardware type, MPU401_HW_XXXX
 * @port: the base address of MPU401 port
 * @info_flags: bitflags MPU401_INFO_XXX
 * @irq: the ISA irq number, -1 if not to be allocated
 * @rrawmidi: the pointer to store the new rawmidi instance
 *
 * Creates a new MPU-401 instance.
 *
 * Note that the rawmidi instance is returned on the rrawmidi argument,
 * not the mpu401 instance itself.  To access to the mpu401 instance,
 * cast from rawmidi->private_data (with struct snd_mpu401 magic-cast).
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_mpu401_uart_new(struct snd_card *card, int device,
                        unsigned short hardware,
                        unsigned long port,
                        unsigned int info_flags,
                        int irq,
                        struct snd_rawmidi ** rrawmidi)
{
        struct snd_mpu401 *mpu;
        struct snd_rawmidi *rmidi;
        int in_enable, out_enable;
        int err;

        if (rrawmidi)
                *rrawmidi = NULL;
        if (! (info_flags & (MPU401_INFO_INPUT | MPU401_INFO_OUTPUT)))
                info_flags |= MPU401_INFO_INPUT | MPU401_INFO_OUTPUT;
        in_enable = (info_flags & MPU401_INFO_INPUT) ? 1 : 0;
        out_enable = (info_flags & MPU401_INFO_OUTPUT) ? 1 : 0;
        err = snd_rawmidi_new(card, "MPU-401U", device,
                              out_enable, in_enable, &rmidi);
        if (err < 0)
                return err;
        mpu = kzalloc_obj(*mpu);
        if (!mpu) {
                err = -ENOMEM;
                goto free_device;
        }
        rmidi->private_data = mpu;
        rmidi->private_free = snd_mpu401_uart_free;
        spin_lock_init(&mpu->input_lock);
        spin_lock_init(&mpu->output_lock);
        spin_lock_init(&mpu->timer_lock);
        mpu->hardware = hardware;
        mpu->irq = -1;
        mpu->rmidi = rmidi;
        if (! (info_flags & MPU401_INFO_INTEGRATED)) {
                int res_size = hardware == MPU401_HW_PC98II ? 4 : 2;
                mpu->res = request_region(port, res_size, "MPU401 UART");
                if (!mpu->res) {
                        dev_err(rmidi->dev,
                                "mpu401_uart: unable to grab port 0x%lx size %d\n",
                                port, res_size);
                        err = -EBUSY;
                        goto free_device;
                }
        }
        if (info_flags & MPU401_INFO_MMIO) {
                mpu->write = mpu401_write_mmio;
                mpu->read = mpu401_read_mmio;
        } else {
                mpu->write = mpu401_write_port;
                mpu->read = mpu401_read_port;
        }
        mpu->port = port;
        if (hardware == MPU401_HW_PC98II)
                mpu->cport = port + 2;
        else
                mpu->cport = port + 1;
        if (irq >= 0) {
                if (request_irq(irq, snd_mpu401_uart_interrupt, 0,
                                "MPU401 UART", (void *) mpu)) {
                        dev_err(rmidi->dev,
                                "mpu401_uart: unable to grab IRQ %d\n", irq);
                        err = -EBUSY;
                        goto free_device;
                }
        }
        if (irq < 0 && !(info_flags & MPU401_INFO_IRQ_HOOK))
                info_flags |= MPU401_INFO_USE_TIMER;
        mpu->info_flags = info_flags;
        mpu->irq = irq;
        if (card->shortname[0])
                snprintf(rmidi->name, sizeof(rmidi->name), "%s MIDI",
                         card->shortname);
        else
                sprintf(rmidi->name, "MPU-401 MIDI %d-%d",card->number, device);
        if (out_enable) {
                snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
                                    &snd_mpu401_uart_output);
                rmidi->info_flags |= SNDRV_RAWMIDI_INFO_OUTPUT;
        }
        if (in_enable) {
                snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
                                    &snd_mpu401_uart_input);
                rmidi->info_flags |= SNDRV_RAWMIDI_INFO_INPUT;
                if (out_enable)
                        rmidi->info_flags |= SNDRV_RAWMIDI_INFO_DUPLEX;
        }
        if (rrawmidi)
                *rrawmidi = rmidi;
        return 0;
free_device:
        snd_device_free(card, rmidi);
        return err;
}

EXPORT_SYMBOL(snd_mpu401_uart_new);