/*      $NetBSD: uchcom.c,v 1.1 2007/09/03 17:57:37 tshiozak Exp $      */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2007, Takanori Watanabe
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Takuya SHIOZAKI (tshiozak@netbsd.org).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Driver for WinChipHead CH9102/343/341/340.
 */

#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>
#include <dev/usb/usbdi_util.h>
#include "usbdevs.h"

#define USB_DEBUG_VAR uchcom_debug
#include <dev/usb/usb_debug.h>
#include <dev/usb/usb_process.h>

#include <dev/usb/serial/usb_serial.h>

#ifdef USB_DEBUG
static int uchcom_debug = 0;

static SYSCTL_NODE(_hw_usb, OID_AUTO, uchcom, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "USB uchcom");
SYSCTL_INT(_hw_usb_uchcom, OID_AUTO, debug, CTLFLAG_RWTUN,
    &uchcom_debug, 0, "uchcom debug level");
#endif

#define UCHCOM_IFACE_INDEX              0
#define UCHCOM_CONFIG_INDEX             0
#define UCHCOM_SECOND_IFACE_INDEX       1

#define UCHCOM_REV_CH340        0x0250
#define UCHCOM_INPUT_BUF_SIZE   8

#define UCHCOM_REQ_GET_VERSION          0x5F
#define UCHCOM_REQ_READ_REG             0x95
#define UCHCOM_REQ_WRITE_REG            0x9A
#define UCHCOM_REQ_RESET                0xA1
#define UCHCOM_REQ_SET_DTRRTS           0xA4
#define UCHCOM_REQ_CH343_WRITE_REG      0xA8

#define UCHCOM_REG_STAT1        0x06
#define UCHCOM_REG_STAT2        0x07
#define UCHCOM_REG_BPS_PRE      0x12
#define UCHCOM_REG_BPS_DIV      0x13
#define UCHCOM_REG_BPS_MOD      0x14
#define UCHCOM_REG_BPS_PAD      0x0F
#define UCHCOM_REG_BREAK1       0x05
#define UCHCOM_REG_LCR1         0x18
#define UCHCOM_REG_LCR2         0x25

#define UCHCOM_VER_20           0x20
#define UCHCOM_VER_30           0x30

#define UCHCOM_BASE_UNKNOWN     0
#define UCHCOM_BPS_MOD_BASE     20000000
#define UCHCOM_BPS_MOD_BASE_OFS 1100

#define UCHCOM_DTR_MASK         0x20
#define UCHCOM_RTS_MASK         0x40

#define UCHCOM_BRK_MASK         0x01
#define UCHCOM_ABRK_MASK        0x10
#define UCHCOM_CH343_BRK_MASK   0x80

#define UCHCOM_LCR1_MASK        0xAF
#define UCHCOM_LCR2_MASK        0x07
#define UCHCOM_LCR1_RX          0x80
#define UCHCOM_LCR1_TX          0x40
#define UCHCOM_LCR1_PARENB      0x08
#define UCHCOM_LCR1_CS5         0x00
#define UCHCOM_LCR1_CS6         0x01
#define UCHCOM_LCR1_CS7         0x02
#define UCHCOM_LCR1_CS8         0x03
#define UCHCOM_LCR1_STOPB       0x04
#define UCHCOM_LCR1_PARODD      0x00
#define UCHCOM_LCR1_PAREVEN     0x10
#define UCHCOM_LCR2_PAREVEN     0x07
#define UCHCOM_LCR2_PARODD      0x06
#define UCHCOM_LCR2_PARMARK     0x05
#define UCHCOM_LCR2_PARSPACE    0x04

#define UCHCOM_INTR_STAT1       0x02
#define UCHCOM_INTR_STAT2       0x03
#define UCHCOM_INTR_LEAST       4

#define UCHCOM_T                0x08
#define UCHCOM_CL               0x04
#define UCHCOM_CH343_CT         0x80
#define UCHCOM_CT               0x90

#define UCHCOM_BULK_BUF_SIZE    1024    /* bytes */

#define TYPE_CH343              1

enum {
        UCHCOM_BULK_DT_WR,
        UCHCOM_BULK_DT_RD,
        UCHCOM_N_TRANSFER,
};

struct uchcom_softc {
        struct ucom_super_softc sc_super_ucom;
        struct ucom_softc sc_ucom;

        struct usb_xfer *sc_xfer[UCHCOM_N_TRANSFER];
        struct usb_xfer *sc_intr_xfer;  /* Interrupt endpoint */
        struct usb_device *sc_udev;
        struct mtx sc_mtx;

        uint8_t sc_dtr;                 /* local copy */
        uint8_t sc_rts;                 /* local copy */
        uint8_t sc_version;
        uint8_t sc_msr;
        uint8_t sc_lsr;                 /* local status register */
        uint8_t sc_chiptype;            /* type of chip */
        uint8_t sc_ctrl_iface_no;
        uint8_t sc_iface_index;
};

static const STRUCT_USB_HOST_ID uchcom_devs[] = {
        {USB_VPI(USB_VENDOR_WCH, USB_PRODUCT_WCH_CH341SER, 0)},
        {USB_VPI(USB_VENDOR_WCH2, USB_PRODUCT_WCH2_CH341SER, 0)},
        {USB_VPI(USB_VENDOR_WCH2, USB_PRODUCT_WCH2_CH341SER_2, 0)},
        {USB_VPI(USB_VENDOR_WCH2, USB_PRODUCT_WCH2_CH341SER_3, 0)},
        {USB_VPI(USB_VENDOR_WCH2, USB_PRODUCT_WCH2_CH343SER, 0)},
        {USB_VPI(USB_VENDOR_WCH2, USB_PRODUCT_WCH2_CH9102SER, 0)},
};

/* protypes */

static void     uchcom_free(struct ucom_softc *);
static int      uchcom_pre_param(struct ucom_softc *, struct termios *);
static void     uchcom_cfg_get_status(struct ucom_softc *, uint8_t *,
                    uint8_t *);
static void     uchcom_cfg_open(struct ucom_softc *ucom);
static void     uchcom_cfg_param(struct ucom_softc *, struct termios *);
static void     uchcom_cfg_set_break(struct ucom_softc *, uint8_t);
static void     uchcom_cfg_set_dtr(struct ucom_softc *, uint8_t);
static void     uchcom_cfg_set_rts(struct ucom_softc *, uint8_t);
static void     uchcom_start_read(struct ucom_softc *);
static void     uchcom_start_write(struct ucom_softc *);
static void     uchcom_stop_read(struct ucom_softc *);
static void     uchcom_stop_write(struct ucom_softc *);
static void     uchcom_update_version(struct uchcom_softc *);
static void     uchcom_convert_status(struct uchcom_softc *, uint8_t);
static void     uchcom_update_status(struct uchcom_softc *);
static void     uchcom_set_dtr_rts(struct uchcom_softc *);
static void     uchcom_calc_baudrate(struct uchcom_softc *, uint32_t, uint8_t *,
                    uint8_t *);
static void     uchcom_set_baudrate(struct uchcom_softc *, uint32_t, uint16_t);
static void     uchcom_poll(struct ucom_softc *ucom);

static device_probe_t uchcom_probe;
static device_attach_t uchcom_attach;
static device_detach_t uchcom_detach;
static void uchcom_free_softc(struct uchcom_softc *);

static usb_callback_t uchcom_intr_callback;
static usb_callback_t uchcom_write_callback;
static usb_callback_t uchcom_read_callback;

static const struct usb_config uchcom_config_data[UCHCOM_N_TRANSFER] = {
        [UCHCOM_BULK_DT_WR] = {
                .type = UE_BULK,
                .endpoint = UE_ADDR_ANY,
                .direction = UE_DIR_OUT,
                .bufsize = UCHCOM_BULK_BUF_SIZE,
                .flags = {.pipe_bof = 1,},
                .callback = &uchcom_write_callback,
        },

        [UCHCOM_BULK_DT_RD] = {
                .type = UE_BULK,
                .endpoint = UE_ADDR_ANY,
                .direction = UE_DIR_IN,
                .bufsize = UCHCOM_BULK_BUF_SIZE,
                .flags = {.pipe_bof = 1,.short_xfer_ok = 1,},
                .callback = &uchcom_read_callback,
        },
};

static const struct usb_config uchcom_intr_config_data[1] = {
        [0] = {
                .type = UE_INTERRUPT,
                .endpoint = UE_ADDR_ANY,
                .direction = UE_DIR_IN,
                .flags = {.pipe_bof = 1,.short_xfer_ok = 1,},
                .bufsize = 0,   /* use wMaxPacketSize */
                .callback = &uchcom_intr_callback,
        },
};

static struct ucom_callback uchcom_callback = {
        .ucom_cfg_get_status = &uchcom_cfg_get_status,
        .ucom_cfg_set_dtr = &uchcom_cfg_set_dtr,
        .ucom_cfg_set_rts = &uchcom_cfg_set_rts,
        .ucom_cfg_set_break = &uchcom_cfg_set_break,
        .ucom_cfg_open = &uchcom_cfg_open,
        .ucom_cfg_param = &uchcom_cfg_param,
        .ucom_pre_param = &uchcom_pre_param,
        .ucom_start_read = &uchcom_start_read,
        .ucom_stop_read = &uchcom_stop_read,
        .ucom_start_write = &uchcom_start_write,
        .ucom_stop_write = &uchcom_stop_write,
        .ucom_poll = &uchcom_poll,
        .ucom_free = &uchcom_free,
};

/* ----------------------------------------------------------------------
 * driver entry points
 */

static int
uchcom_probe(device_t dev)
{
        struct usb_attach_arg *uaa = device_get_ivars(dev);

        DPRINTFN(11, "\n");

        if (uaa->usb_mode != USB_MODE_HOST) {
                return (ENXIO);
        }
        if (uaa->info.bConfigIndex != UCHCOM_CONFIG_INDEX) {
                return (ENXIO);
        }
        if (uaa->info.bIfaceIndex != UCHCOM_IFACE_INDEX) {
                return (ENXIO);
        }
        return (usbd_lookup_id_by_uaa(uchcom_devs, sizeof(uchcom_devs), uaa));
}

static int
uchcom_attach(device_t dev)
{
        struct uchcom_softc *sc = device_get_softc(dev);
        struct usb_attach_arg *uaa = device_get_ivars(dev);
        struct usb_interface *iface;
        struct usb_interface_descriptor *id;
        int error;

        DPRINTFN(11, "\n");

        device_set_usb_desc(dev);
        mtx_init(&sc->sc_mtx, "uchcom", NULL, MTX_DEF);
        ucom_ref(&sc->sc_super_ucom);

        sc->sc_udev = uaa->device;

        switch (uaa->info.idProduct) {
        case USB_PRODUCT_WCH2_CH341SER:
                device_printf(dev, "CH340 detected\n");
                break;
        case USB_PRODUCT_WCH2_CH341SER_2:
        case USB_PRODUCT_WCH2_CH341SER_3:
                device_printf(dev, "CH341 detected\n");
                break;
        case USB_PRODUCT_WCH2_CH343SER:
                device_printf(dev, "CH343 detected\n");
                break;
        case USB_PRODUCT_WCH2_CH9102SER:
                device_printf(dev, "CH9102 detected\n");
                break;
        default:
                device_printf(dev, "New CH340/CH341/CH343/CH9102 product "
                    "0x%04x detected\n", uaa->info.idProduct);
                break;
        }

        /* CH343/CH9102 has two interfaces. */
        sc->sc_ctrl_iface_no = uaa->info.bIfaceNum;

        iface = usbd_get_iface(uaa->device, UCHCOM_SECOND_IFACE_INDEX);
        if (iface) {
                id = usbd_get_interface_descriptor(iface);
                if (id == NULL) {
                        device_printf(dev, "no interface descriptor\n");
                        goto detach;
                }
                sc->sc_iface_index = UCHCOM_SECOND_IFACE_INDEX;
                usbd_set_parent_iface(uaa->device, UCHCOM_SECOND_IFACE_INDEX,
                    uaa->info.bIfaceIndex);
                sc->sc_chiptype = TYPE_CH343;
        } else {
                sc->sc_iface_index = UCHCOM_IFACE_INDEX;
        }

        /* Setup all transfers. */
        error = usbd_transfer_setup(uaa->device, &sc->sc_iface_index,
            sc->sc_xfer, uchcom_config_data, UCHCOM_N_TRANSFER, sc,
            &sc->sc_mtx);
        if (error) {
                device_printf(dev, "could not allocate all pipes\n");
                goto detach;
        }
        error = usbd_transfer_setup(uaa->device, &sc->sc_ctrl_iface_no,
            &sc->sc_intr_xfer, uchcom_intr_config_data, 1, sc, &sc->sc_mtx);
        if (error) {
                device_printf(dev, "allocating USB transfers failed for "
                    "interrupt\n");
                goto detach;
        }

        /* clear stall at first run */
        mtx_lock(&sc->sc_mtx);
        usbd_xfer_set_stall(sc->sc_xfer[UCHCOM_BULK_DT_WR]);
        usbd_xfer_set_stall(sc->sc_xfer[UCHCOM_BULK_DT_RD]);
        mtx_unlock(&sc->sc_mtx);

        error = ucom_attach(&sc->sc_super_ucom, &sc->sc_ucom, 1, sc,
            &uchcom_callback, &sc->sc_mtx);
        if (error) {
                goto detach;
        }
        ucom_set_pnpinfo_usb(&sc->sc_super_ucom, dev);

        return (0);

detach:
        uchcom_detach(dev);
        return (ENXIO);
}

static int
uchcom_detach(device_t dev)
{
        struct uchcom_softc *sc = device_get_softc(dev);

        DPRINTFN(11, "\n");

        ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
        usbd_transfer_unsetup(sc->sc_xfer, UCHCOM_N_TRANSFER);

        device_claim_softc(dev);

        uchcom_free_softc(sc);

        return (0);
}

UCOM_UNLOAD_DRAIN(uchcom);

static void
uchcom_free_softc(struct uchcom_softc *sc)
{
        if (ucom_unref(&sc->sc_super_ucom)) {
                mtx_destroy(&sc->sc_mtx);
                device_free_softc(sc);
        }
}

static void
uchcom_free(struct ucom_softc *ucom)
{
        uchcom_free_softc(ucom->sc_parent);
}

/* ----------------------------------------------------------------------
 * low level i/o
 */

static void
uchcom_ctrl_write(struct uchcom_softc *sc, uint8_t reqno,
    uint16_t value, uint16_t index)
{
        struct usb_device_request req;

        req.bmRequestType = UT_WRITE_VENDOR_DEVICE;
        req.bRequest = reqno;
        USETW(req.wValue, value);
        USETW(req.wIndex, index);
        USETW(req.wLength, 0);

        DPRINTF("WR REQ 0x%02X VAL 0x%04X IDX 0x%04X\n",
            reqno, value, index);
        ucom_cfg_do_request(sc->sc_udev,
            &sc->sc_ucom, &req, NULL, 0, 1000);
}

static void
uchcom_ctrl_read(struct uchcom_softc *sc, uint8_t reqno,
    uint16_t value, uint16_t index, void *buf, uint16_t buflen)
{
        struct usb_device_request req;

        req.bmRequestType = UT_READ_VENDOR_DEVICE;
        req.bRequest = reqno;
        USETW(req.wValue, value);
        USETW(req.wIndex, index);
        USETW(req.wLength, buflen);

        DPRINTF("RD REQ 0x%02X VAL 0x%04X IDX 0x%04X LEN %d\n",
            reqno, value, index, buflen);
        ucom_cfg_do_request(sc->sc_udev,
            &sc->sc_ucom, &req, buf, USB_SHORT_XFER_OK, 1000);
}

static void
uchcom_write_reg(struct uchcom_softc *sc,
    uint8_t reg1, uint8_t val1, uint8_t reg2, uint8_t val2)
{
        DPRINTF("0x%02X<-0x%02X, 0x%02X<-0x%02X\n",
            (unsigned)reg1, (unsigned)val1,
            (unsigned)reg2, (unsigned)val2);
        uchcom_ctrl_write(
            sc, 
            (sc->sc_chiptype != TYPE_CH343) ?
            UCHCOM_REQ_WRITE_REG : UCHCOM_REQ_CH343_WRITE_REG,
            reg1 | ((uint16_t)reg2 << 8), val1 | ((uint16_t)val2 << 8));
}

static void
uchcom_read_reg(struct uchcom_softc *sc,
    uint8_t reg1, uint8_t *rval1, uint8_t reg2, uint8_t *rval2)
{
        uint8_t buf[UCHCOM_INPUT_BUF_SIZE];

        uchcom_ctrl_read(
            sc, UCHCOM_REQ_READ_REG,
            reg1 | ((uint16_t)reg2 << 8), 0, buf, sizeof(buf));

        DPRINTF("0x%02X->0x%02X, 0x%02X->0x%02X\n",
            (unsigned)reg1, (unsigned)buf[0],
            (unsigned)reg2, (unsigned)buf[1]);

        if (rval1)
                *rval1 = buf[0];
        if (rval2)
                *rval2 = buf[1];
}

static void
uchcom_get_version(struct uchcom_softc *sc, uint8_t *rver)
{
        uint8_t buf[UCHCOM_INPUT_BUF_SIZE];

        uchcom_ctrl_read(sc, UCHCOM_REQ_GET_VERSION, 0, 0, buf, sizeof(buf));

        if (rver)
                *rver = buf[0];
}

static void
uchcom_get_status(struct uchcom_softc *sc, uint8_t *rval)
{
        uchcom_read_reg(sc, UCHCOM_REG_STAT1, rval, UCHCOM_REG_STAT2, NULL);
}

static void
uchcom_set_dtr_rts_10(struct uchcom_softc *sc, uint8_t val)
{
        uchcom_write_reg(sc, UCHCOM_REG_STAT1, val, UCHCOM_REG_STAT1, val);
}

static void
uchcom_set_dtr_rts_20(struct uchcom_softc *sc, uint8_t val)
{
        uchcom_ctrl_write(sc, UCHCOM_REQ_SET_DTRRTS, val, 0);
}

/* ----------------------------------------------------------------------
 * middle layer
 */

static void
uchcom_update_version(struct uchcom_softc *sc)
{
        uchcom_get_version(sc, &sc->sc_version);
        DPRINTF("Chip version: 0x%02x\n", sc->sc_version);
}

static void
uchcom_convert_status(struct uchcom_softc *sc, uint8_t cur)
{
        cur = ~cur & 0x0F;
        sc->sc_msr = (cur << 4) | ((sc->sc_msr >> 4) ^ cur);
}

static void
uchcom_update_status(struct uchcom_softc *sc)
{
        uint8_t cur;

        uchcom_get_status(sc, &cur);
        uchcom_convert_status(sc, cur);
}

static void
uchcom_set_dtr_rts(struct uchcom_softc *sc)
{
        uint8_t val = 0;

        if (sc->sc_dtr)
                val |= UCHCOM_DTR_MASK;
        if (sc->sc_rts)
                val |= UCHCOM_RTS_MASK;

        if (sc->sc_version < UCHCOM_VER_20)
                uchcom_set_dtr_rts_10(sc, ~val);
        else
                uchcom_set_dtr_rts_20(sc, ~val);
}

static void
uchcom_cfg_set_break(struct ucom_softc *ucom, uint8_t onoff)
{
        struct uchcom_softc *sc = ucom->sc_parent;
        uint8_t brk1;
        uint8_t brk2;

        if (sc->sc_chiptype == TYPE_CH343) {
                brk1 = UCHCOM_CH343_BRK_MASK;
                if (!onoff)
                        brk1 |= UCHCOM_ABRK_MASK;
                uchcom_write_reg(sc, brk1, 0, 0, 0);
        } else {
                uchcom_read_reg(sc, UCHCOM_REG_BREAK1, &brk1, UCHCOM_REG_LCR1,
                    &brk2);
                if (onoff) {
                        /* on - clear bits */
                        brk1 &= ~UCHCOM_BRK_MASK;
                        brk2 &= ~UCHCOM_LCR1_TX;
                } else {
                        /* off - set bits */
                        brk1 |= UCHCOM_BRK_MASK;
                        brk2 |= UCHCOM_LCR1_TX;
                }
                uchcom_write_reg(sc, UCHCOM_REG_BREAK1, brk1, UCHCOM_REG_LCR1,
                    brk2);
        }
}

static void
uchcom_calc_baudrate(struct uchcom_softc *sc, uint32_t rate, uint8_t *divisor,
    uint8_t *factor)
{
        uint32_t clk = 12000000;

        if (rate >= 256000 && sc->sc_chiptype == TYPE_CH343)
                *divisor = 7;
        else if (rate > 23529) {
                clk /= 2;
                *divisor = 3;
        } else if (rate > 2941) {
                clk /=  16;
                *divisor = 2;
        } else if (rate > 367) {
                clk /= 128;
                *divisor = 1;
        } else {
                clk = 11719;
                *divisor = 0;
        }

        *factor = 256 - clk / rate;

        if (rate == 921600 && sc->sc_chiptype != TYPE_CH343) {
                *divisor = 7;
                *factor = 243;
        }
}

static void
uchcom_set_baudrate(struct uchcom_softc *sc, uint32_t rate, uint16_t lcr)
{
        uint16_t idx;
        uint8_t factor, div;

        uchcom_calc_baudrate(sc, rate, &div, &factor);
        div |= (sc->sc_chiptype != TYPE_CH343) ? 0x80 : 0x00;
        idx = (factor << 8) | div;

        uchcom_ctrl_write(sc, UCHCOM_REQ_RESET, lcr, idx);
}

/* ----------------------------------------------------------------------
 * methods for ucom
 */
static void
uchcom_cfg_get_status(struct ucom_softc *ucom, uint8_t *lsr, uint8_t *msr)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        DPRINTF("\n");

        /* XXX Note: sc_lsr is always zero */
        *lsr = sc->sc_lsr;
        *msr = sc->sc_msr;
}

static void
uchcom_cfg_set_dtr(struct ucom_softc *ucom, uint8_t onoff)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        DPRINTF("onoff = %d\n", onoff);

        sc->sc_dtr = onoff;
        uchcom_set_dtr_rts(sc);
}

static void
uchcom_cfg_set_rts(struct ucom_softc *ucom, uint8_t onoff)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        DPRINTF("onoff = %d\n", onoff);

        sc->sc_rts = onoff;
        uchcom_set_dtr_rts(sc);
}

static void
uchcom_cfg_open(struct ucom_softc *ucom)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        DPRINTF("\n");

        if (sc->sc_chiptype != TYPE_CH343) {
                /* Set default configuration. */
                uchcom_get_version(sc, NULL);
                uchcom_ctrl_write(sc, UCHCOM_REQ_RESET, 0, 0);
                uchcom_write_reg(sc, UCHCOM_REG_BPS_PRE, 0x82,
                    UCHCOM_REG_BPS_DIV, 0xd9);
                uchcom_write_reg(sc, 0x2c, 0x07, UCHCOM_REG_BPS_PAD, 0);
        }
        uchcom_update_version(sc);
        uchcom_update_status(sc);
}

static int
uchcom_pre_param(struct ucom_softc *ucom, struct termios *t)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        /* 
         * Check requested baud rate.
         * The CH340/CH341 can set any baud rate up to 2Mb.
         * The CH9102/CH343 can set any baud rate up to 6Mb.
         */
        switch (sc->sc_chiptype) {
        case TYPE_CH343:
                if (t->c_ospeed <= 6000000)
                        return (0);
                break;
        default:
                if (t->c_ospeed <= 2000000)
                        return (0);
                break;
        }

        return (EIO);
}

static void
uchcom_cfg_param(struct ucom_softc *ucom, struct termios *t)
{
        struct uchcom_softc *sc = ucom->sc_parent;
        uint8_t lcr;

        lcr = UCHCOM_LCR1_RX | UCHCOM_LCR1_TX;

        if (t->c_cflag & CSTOPB)
                lcr |= UCHCOM_LCR1_STOPB;

        if (t->c_cflag & PARENB) {
                lcr |= UCHCOM_LCR1_PARENB;
                if (t->c_cflag & PARODD)
                        lcr |= UCHCOM_LCR1_PARODD;
                else
                        lcr |= UCHCOM_LCR1_PAREVEN;
        }

        switch (t->c_cflag & CSIZE) {
        case CS5:
                lcr |= UCHCOM_LCR1_CS5;
                break;
        case CS6:
                lcr |= UCHCOM_LCR1_CS6;
                break;
        case CS7:
                lcr |= UCHCOM_LCR1_CS7;
                break;
        case CS8:
        default:
                lcr |= UCHCOM_LCR1_CS8;
                break;
        }

        if (sc->sc_chiptype == TYPE_CH343)
                uchcom_set_baudrate(sc, t->c_ospeed,
                    UCHCOM_T | UCHCOM_CL | UCHCOM_CH343_CT | lcr << 8);
        else
                uchcom_set_baudrate(sc, t->c_ospeed,
                    UCHCOM_T | UCHCOM_CL | UCHCOM_CT | lcr << 8);

        uchcom_set_dtr_rts(sc);
        uchcom_update_status(sc);
}

static void
uchcom_start_read(struct ucom_softc *ucom)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        /* start interrupt endpoint */
        usbd_transfer_start(sc->sc_intr_xfer);

        /* start read endpoint */
        usbd_transfer_start(sc->sc_xfer[UCHCOM_BULK_DT_RD]);
}

static void
uchcom_stop_read(struct ucom_softc *ucom)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        /* stop interrupt endpoint */
        usbd_transfer_stop(sc->sc_intr_xfer);

        /* stop read endpoint */
        usbd_transfer_stop(sc->sc_xfer[UCHCOM_BULK_DT_RD]);
}

static void
uchcom_start_write(struct ucom_softc *ucom)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        usbd_transfer_start(sc->sc_xfer[UCHCOM_BULK_DT_WR]);
}

static void
uchcom_stop_write(struct ucom_softc *ucom)
{
        struct uchcom_softc *sc = ucom->sc_parent;

        usbd_transfer_stop(sc->sc_xfer[UCHCOM_BULK_DT_WR]);
}

/* ----------------------------------------------------------------------
 * callback when the modem status is changed.
 */
static void
uchcom_intr_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct uchcom_softc *sc = usbd_xfer_softc(xfer);
        struct usb_page_cache *pc;
        uint32_t intrstat;
        uint8_t buf[16];
        int actlen;

        usbd_xfer_status(xfer, &actlen, NULL, NULL, NULL);

        switch (USB_GET_STATE(xfer)) {
        case USB_ST_TRANSFERRED:

                DPRINTF("actlen = %u\n", actlen);

                if (actlen >= UCHCOM_INTR_LEAST) {
                        pc = usbd_xfer_get_frame(xfer, 0);
                        usbd_copy_out(pc, 0, buf, sizeof(buf));

                        intrstat = (sc->sc_chiptype == TYPE_CH343) ?
                            actlen - 1 : UCHCOM_INTR_STAT1;

                        uchcom_convert_status(sc, buf[intrstat]);
                        ucom_status_change(&sc->sc_ucom);
                }
        case USB_ST_SETUP:
tr_setup:
                usbd_xfer_set_frame_len(xfer, 0, usbd_xfer_max_len(xfer));
                usbd_transfer_submit(xfer);
                break;

        default:                        /* Error */
                if (error != USB_ERR_CANCELLED) {
                        /* try to clear stall first */
                        usbd_xfer_set_stall(xfer);
                        goto tr_setup;
                }
                break;
        }
}

static void
uchcom_write_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct uchcom_softc *sc = usbd_xfer_softc(xfer);
        struct usb_page_cache *pc;
        uint32_t actlen;

        switch (USB_GET_STATE(xfer)) {
        case USB_ST_SETUP:
        case USB_ST_TRANSFERRED:
tr_setup:
                pc = usbd_xfer_get_frame(xfer, 0);
                if (ucom_get_data(&sc->sc_ucom, pc, 0,
                    usbd_xfer_max_len(xfer), &actlen)) {
                        DPRINTF("actlen = %d\n", actlen);

                        usbd_xfer_set_frame_len(xfer, 0, actlen);
                        usbd_transfer_submit(xfer);
                }
                break;

        default:                        /* Error */
                if (error != USB_ERR_CANCELLED) {
                        /* try to clear stall first */
                        usbd_xfer_set_stall(xfer);
                        goto tr_setup;
                }
                break;
        }
}

static void
uchcom_read_callback(struct usb_xfer *xfer, usb_error_t error)
{
        struct uchcom_softc *sc = usbd_xfer_softc(xfer);
        struct usb_page_cache *pc;
        int actlen;

        usbd_xfer_status(xfer, &actlen, NULL, NULL, NULL);

        switch (USB_GET_STATE(xfer)) {
        case USB_ST_TRANSFERRED:

                if (actlen > 0) {
                        pc = usbd_xfer_get_frame(xfer, 0);
                        ucom_put_data(&sc->sc_ucom, pc, 0, actlen);
                }

        case USB_ST_SETUP:
tr_setup:
                usbd_xfer_set_frame_len(xfer, 0, usbd_xfer_max_len(xfer));
                usbd_transfer_submit(xfer);
                break;

        default:                        /* Error */
                if (error != USB_ERR_CANCELLED) {
                        /* try to clear stall first */
                        usbd_xfer_set_stall(xfer);
                        goto tr_setup;
                }
                break;
        }
}

static void
uchcom_poll(struct ucom_softc *ucom)
{
        struct uchcom_softc *sc = ucom->sc_parent;
        usbd_transfer_poll(sc->sc_xfer, UCHCOM_N_TRANSFER);
}

static device_method_t uchcom_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe, uchcom_probe),
        DEVMETHOD(device_attach, uchcom_attach),
        DEVMETHOD(device_detach, uchcom_detach),
        DEVMETHOD_END
};

static driver_t uchcom_driver = {
        .name = "uchcom",
        .methods = uchcom_methods,
        .size = sizeof(struct uchcom_softc)
};

DRIVER_MODULE(uchcom, uhub, uchcom_driver, NULL, NULL);
MODULE_DEPEND(uchcom, ucom, 1, 1, 1);
MODULE_DEPEND(uchcom, usb, 1, 1, 1);
MODULE_VERSION(uchcom, 1);
USB_PNP_HOST_INFO(uchcom_devs);