// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (c) 2000-2001 Vojtech Pavlik <vojtech@ucw.cz>
 *  Copyright (c) 2001, 2007 Johann Deneux <johann.deneux@gmail.com>
 *
 *  USB/RS232 I-Force joysticks and wheels.
 */

#include <linux/serio.h>
#include "iforce.h"

struct iforce_serio {
        struct iforce iforce;

        struct serio *serio;
        int idx, pkt, len, id;
        u8 csum;
        u8 expect_packet;
        u8 cmd_response[IFORCE_MAX_LENGTH];
        u8 cmd_response_len;
        u8 data_in[IFORCE_MAX_LENGTH];
};

static void iforce_serio_xmit(struct iforce *iforce)
{
        struct iforce_serio *iforce_serio = container_of(iforce,
                                                         struct iforce_serio,
                                                         iforce);
        unsigned char cs;
        int i;

        if (test_and_set_bit(IFORCE_XMIT_RUNNING, iforce->xmit_flags)) {
                set_bit(IFORCE_XMIT_AGAIN, iforce->xmit_flags);
                return;
        }

        guard(spinlock_irqsave)(&iforce->xmit_lock);

        do {
                if (iforce->xmit.head == iforce->xmit.tail)
                        break;

                cs = 0x2b;

                serio_write(iforce_serio->serio, 0x2b);

                serio_write(iforce_serio->serio,
                            iforce->xmit.buf[iforce->xmit.tail]);
                cs ^= iforce->xmit.buf[iforce->xmit.tail];
                XMIT_INC(iforce->xmit.tail, 1);

                for (i = iforce->xmit.buf[iforce->xmit.tail]; i >= 0; --i) {
                        serio_write(iforce_serio->serio,
                                    iforce->xmit.buf[iforce->xmit.tail]);
                        cs ^= iforce->xmit.buf[iforce->xmit.tail];
                        XMIT_INC(iforce->xmit.tail, 1);
                }

                serio_write(iforce_serio->serio, cs);

        } while (test_and_clear_bit(IFORCE_XMIT_AGAIN, iforce->xmit_flags));

        iforce_clear_xmit_and_wake(iforce);
}

static int iforce_serio_get_id(struct iforce *iforce, u8 id,
                               u8 *response_data, size_t *response_len)
{
        struct iforce_serio *iforce_serio = container_of(iforce,
                                                         struct iforce_serio,
                                                         iforce);

        iforce_serio->expect_packet = HI(FF_CMD_QUERY);
        iforce_serio->cmd_response_len = 0;

        iforce_send_packet(iforce, FF_CMD_QUERY, &id);

        wait_event_interruptible_timeout(iforce->wait,
                                         !iforce_serio->expect_packet, HZ);

        if (iforce_serio->expect_packet) {
                iforce_serio->expect_packet = 0;
                return -ETIMEDOUT;
        }

        if (iforce_serio->cmd_response[0] != id)
                return -EIO;

        memcpy(response_data, iforce_serio->cmd_response,
               iforce_serio->cmd_response_len);
        *response_len = iforce_serio->cmd_response_len;

        return 0;
}

static int iforce_serio_start_io(struct iforce *iforce)
{
        /* No special handling required */
        return 0;
}

static void iforce_serio_stop_io(struct iforce *iforce)
{
        //TODO: Wait for the last packets to be sent
}

static const struct iforce_xport_ops iforce_serio_xport_ops = {
        .xmit           = iforce_serio_xmit,
        .get_id         = iforce_serio_get_id,
        .start_io       = iforce_serio_start_io,
        .stop_io        = iforce_serio_stop_io,
};

static void iforce_serio_write_wakeup(struct serio *serio)
{
        struct iforce *iforce = serio_get_drvdata(serio);

        iforce_serio_xmit(iforce);
}

static irqreturn_t iforce_serio_irq(struct serio *serio,
                                    unsigned char data, unsigned int flags)
{
        struct iforce_serio *iforce_serio = serio_get_drvdata(serio);
        struct iforce *iforce = &iforce_serio->iforce;

        if (!iforce_serio->pkt) {
                if (data == 0x2b)
                        iforce_serio->pkt = 1;
                goto out;
        }

        if (!iforce_serio->id) {
                if (data > 3 && data != 0xff)
                        iforce_serio->pkt = 0;
                else
                        iforce_serio->id = data;
                goto out;
        }

        if (!iforce_serio->len) {
                if (data > IFORCE_MAX_LENGTH) {
                        iforce_serio->pkt = 0;
                        iforce_serio->id = 0;
                } else {
                        iforce_serio->len = data;
                }
                goto out;
        }

        if (iforce_serio->idx < iforce_serio->len) {
                iforce_serio->data_in[iforce_serio->idx++] = data;
                iforce_serio->csum += data;
                goto out;
        }

        if (iforce_serio->idx == iforce_serio->len) {
                /* Handle command completion */
                if (iforce_serio->expect_packet == iforce_serio->id) {
                        iforce_serio->expect_packet = 0;
                        memcpy(iforce_serio->cmd_response,
                               iforce_serio->data_in, IFORCE_MAX_LENGTH);
                        iforce_serio->cmd_response_len = iforce_serio->len;

                        /* Signal that command is done */
                        wake_up_all(&iforce->wait);
                } else if (likely(iforce->type)) {
                        iforce_process_packet(iforce, iforce_serio->id,
                                              iforce_serio->data_in,
                                              iforce_serio->len);
                }

                iforce_serio->pkt = 0;
                iforce_serio->id  = 0;
                iforce_serio->len = 0;
                iforce_serio->idx = 0;
                iforce_serio->csum = 0;
        }
out:
        return IRQ_HANDLED;
}

static int iforce_serio_connect(struct serio *serio, struct serio_driver *drv)
{
        struct iforce_serio *iforce_serio;
        int err;

        iforce_serio = kzalloc_obj(*iforce_serio);
        if (!iforce_serio)
                return -ENOMEM;

        iforce_serio->iforce.xport_ops = &iforce_serio_xport_ops;

        iforce_serio->serio = serio;
        serio_set_drvdata(serio, iforce_serio);

        err = serio_open(serio, drv);
        if (err)
                goto fail1;

        err = iforce_init_device(&serio->dev, BUS_RS232, &iforce_serio->iforce);
        if (err)
                goto fail2;

        return 0;

 fail2: serio_close(serio);
 fail1: serio_set_drvdata(serio, NULL);
        kfree(iforce_serio);
        return err;
}

static void iforce_serio_disconnect(struct serio *serio)
{
        struct iforce_serio *iforce_serio = serio_get_drvdata(serio);

        input_unregister_device(iforce_serio->iforce.dev);
        serio_close(serio);
        serio_set_drvdata(serio, NULL);
        kfree(iforce_serio);
}

static const struct serio_device_id iforce_serio_ids[] = {
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_IFORCE,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        { 0 }
};

MODULE_DEVICE_TABLE(serio, iforce_serio_ids);

struct serio_driver iforce_serio_drv = {
        .driver         = {
                .name   = "iforce",
        },
        .description    = "RS232 I-Force joysticks and wheels driver",
        .id_table       = iforce_serio_ids,
        .write_wakeup   = iforce_serio_write_wakeup,
        .interrupt      = iforce_serio_irq,
        .connect        = iforce_serio_connect,
        .disconnect     = iforce_serio_disconnect,
};

module_serio_driver(iforce_serio_drv);

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>, Johann Deneux <johann.deneux@gmail.com>");
MODULE_DESCRIPTION("RS232 I-Force joysticks and wheels driver");
MODULE_LICENSE("GPL");