/*      $NetBSD: uchcom.c,v 1.40 2021/08/07 16:19:17 thorpej Exp $      */

/*
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uchcom.c,v 1.40 2021/08/07 16:19:17 thorpej Exp $");

#ifdef _KERNEL_OPT
#include "opt_usb.h"
#endif

/*
 * driver for WinChipHead CH341/340, the worst USB-serial chip in the world.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/ioctl.h>
#include <sys/conf.h>
#include <sys/tty.h>
#include <sys/file.h>
#include <sys/select.h>
#include <sys/proc.h>
#include <sys/device.h>
#include <sys/poll.h>

#include <dev/usb/usb.h>

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

#include <dev/usb/ucomvar.h>

#ifdef UCHCOM_DEBUG
#define DPRINTFN(n, x)  if (uchcomdebug > (n)) printf x
int     uchcomdebug = 0;
#else
#define DPRINTFN(n, x)
#endif
#define DPRINTF(x) DPRINTFN(0, x)

#define UCHCOM_IFACE_INDEX      0
#define UCHCOM_CONFIG_INDEX     0

#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_REG_STAT1        0x06
#define UCHCOM_REG_STAT2        0x07
#define UCHCOM_REG_BPS_PRE      0x12
#define UCHCOM_REG_BPS_DIV      0x13
#define UCHCOM_REG_BREAK        0x05
#define UCHCOM_REG_LCR          0x18
#define UCHCOM_REG_LCR2         0x25

#define UCHCOM_VER_20           0x20
#define UCHCOM_VER_30           0x30

#define UCHCOM_BPS_PRE_IMM      0x80    /* CH341: immediate RX forwarding */

#define UCHCOM_DTR_MASK         0x20
#define UCHCOM_RTS_MASK         0x40

#define UCHCOM_BREAK_MASK       0x01

#define UCHCOM_LCR_CS5          0x00
#define UCHCOM_LCR_CS6          0x01
#define UCHCOM_LCR_CS7          0x02
#define UCHCOM_LCR_CS8          0x03
#define UCHCOM_LCR_STOPB        0x04
#define UCHCOM_LCR_PARENB       0x08
#define UCHCOM_LCR_PARODD       0x00
#define UCHCOM_LCR_PAREVEN      0x10
#define UCHCOM_LCR_PARMARK      0x20
#define UCHCOM_LCR_PARSPACE     0x30
#define UCHCOM_LCR_TXE          0x40
#define UCHCOM_LCR_RXE          0x80

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

#define UCHCOMIBUFSIZE 256
#define UCHCOMOBUFSIZE 256

struct uchcom_softc
{
        device_t                sc_dev;
        struct usbd_device *    sc_udev;
        device_t                sc_subdev;
        struct usbd_interface * sc_iface;
        bool                    sc_dying;
        /* */
        int                     sc_intr_endpoint;
        int                     sc_intr_size;
        struct usbd_pipe *      sc_intr_pipe;
        u_char                  *sc_intr_buf;
        /* */
        uint8_t                 sc_version;
        int                     sc_dtr;
        int                     sc_rts;
        u_char                  sc_lsr;
        u_char                  sc_msr;
};

struct uchcom_endpoints
{
        int             ep_bulkin;
        int             ep_bulkout;
        int             ep_intr;
        int             ep_intr_size;
};

struct uchcom_divider
{
        uint8_t         dv_prescaler;
        uint8_t         dv_div;
};

/* 0,1,2,3,7 are prescale factors for given 4x 12000000 clock formula */
static const uint32_t rates4x[8] = {
        [0] = 4 * 12000000 / 1024,
        [1] = 4 * 12000000 / 128,
        [2] = 4 * 12000000 / 16,
        [3] = 4 * 12000000 / 2,
        [7] = 4 * 12000000,
};

static const struct usb_devno uchcom_devs[] = {
        { USB_VENDOR_QINHENG2, USB_PRODUCT_QINHENG2_CH341SER },
        { USB_VENDOR_QINHENG, USB_PRODUCT_QINHENG_CH340 },
        { USB_VENDOR_QINHENG, USB_PRODUCT_QINHENG_CH341_ASP },
};
#define uchcom_lookup(v, p)     usb_lookup(uchcom_devs, v, p)

static void     uchcom_get_status(void *, int, u_char *, u_char *);
static void     uchcom_set(void *, int, int, int);
static int      uchcom_param(void *, int, struct termios *);
static int      uchcom_open(void *, int);
static void     uchcom_close(void *, int);
static void     uchcom_intr(struct usbd_xfer *, void *,
                            usbd_status);

static int      set_config(struct uchcom_softc *);
static int      find_ifaces(struct uchcom_softc *, struct usbd_interface **);
static int      find_endpoints(struct uchcom_softc *,
                               struct uchcom_endpoints *);
static void     close_intr_pipe(struct uchcom_softc *);


static const struct     ucom_methods uchcom_methods = {
        .ucom_get_status        = uchcom_get_status,
        .ucom_set               = uchcom_set,
        .ucom_param             = uchcom_param,
        .ucom_open              = uchcom_open,
        .ucom_close             = uchcom_close,
};

static int      uchcom_match(device_t, cfdata_t, void *);
static void     uchcom_attach(device_t, device_t, void *);
static void     uchcom_childdet(device_t, device_t);
static int      uchcom_detach(device_t, int);

CFATTACH_DECL2_NEW(uchcom,
    sizeof(struct uchcom_softc),
    uchcom_match,
    uchcom_attach,
    uchcom_detach,
    NULL,
    NULL,
    uchcom_childdet);

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

static int
uchcom_match(device_t parent, cfdata_t match, void *aux)
{
        struct usb_attach_arg *uaa = aux;

        return (uchcom_lookup(uaa->uaa_vendor, uaa->uaa_product) != NULL ?
                UMATCH_VENDOR_PRODUCT : UMATCH_NONE);
}

static void
uchcom_attach(device_t parent, device_t self, void *aux)
{
        struct uchcom_softc *sc = device_private(self);
        struct usb_attach_arg *uaa = aux;
        struct usbd_device *dev = uaa->uaa_device;
        char *devinfop;
        struct uchcom_endpoints endpoints;
        struct ucom_attach_args ucaa;

        aprint_naive("\n");
        aprint_normal("\n");

        devinfop = usbd_devinfo_alloc(dev, 0);
        aprint_normal_dev(self, "%s\n", devinfop);
        usbd_devinfo_free(devinfop);

        sc->sc_dev = self;
        sc->sc_udev = dev;
        sc->sc_dying = false;
        sc->sc_dtr = sc->sc_rts = -1;
        sc->sc_lsr = sc->sc_msr = 0;

        DPRINTF(("\n\nuchcom attach: sc=%p\n", sc));

        if (set_config(sc))
                goto failed;

        if (find_ifaces(sc, &sc->sc_iface))
                goto failed;

        if (find_endpoints(sc, &endpoints))
                goto failed;

        sc->sc_intr_endpoint = endpoints.ep_intr;
        sc->sc_intr_size = endpoints.ep_intr_size;

        /* setup ucom layer */
        ucaa.ucaa_portno = UCOM_UNK_PORTNO;
        ucaa.ucaa_bulkin = endpoints.ep_bulkin;
        ucaa.ucaa_bulkout = endpoints.ep_bulkout;
        ucaa.ucaa_ibufsize = UCHCOMIBUFSIZE;
        ucaa.ucaa_obufsize = UCHCOMOBUFSIZE;
        ucaa.ucaa_ibufsizepad = UCHCOMIBUFSIZE;
        ucaa.ucaa_opkthdrlen = 0;
        ucaa.ucaa_device = dev;
        ucaa.ucaa_iface = sc->sc_iface;
        ucaa.ucaa_methods = &uchcom_methods;
        ucaa.ucaa_arg = sc;
        ucaa.ucaa_info = NULL;

        usbd_add_drv_event(USB_EVENT_DRIVER_ATTACH, sc->sc_udev, sc->sc_dev);

        sc->sc_subdev = config_found(self, &ucaa, ucomprint,
            CFARGS(.submatch = ucomsubmatch));

        return;

failed:
        sc->sc_dying = true;
        return;
}

static void
uchcom_childdet(device_t self, device_t child)
{
        struct uchcom_softc *sc = device_private(self);

        KASSERT(sc->sc_subdev == child);
        sc->sc_subdev = NULL;
}

static int
uchcom_detach(device_t self, int flags)
{
        struct uchcom_softc *sc = device_private(self);
        int rv = 0;

        DPRINTF(("uchcom_detach: sc=%p flags=%d\n", sc, flags));

        close_intr_pipe(sc);

        sc->sc_dying = true;

        if (sc->sc_subdev != NULL) {
                rv = config_detach(sc->sc_subdev, flags);
                sc->sc_subdev = NULL;
        }

        usbd_add_drv_event(USB_EVENT_DRIVER_DETACH, sc->sc_udev, sc->sc_dev);

        return rv;
}

static int
set_config(struct uchcom_softc *sc)
{
        usbd_status err;

        err = usbd_set_config_index(sc->sc_udev, UCHCOM_CONFIG_INDEX, 1);
        if (err) {
                aprint_error_dev(sc->sc_dev,
                    "failed to set configuration: %s\n", usbd_errstr(err));
                return -1;
        }

        return 0;
}

static int
find_ifaces(struct uchcom_softc *sc, struct usbd_interface **riface)
{
        usbd_status err;

        err = usbd_device2interface_handle(sc->sc_udev, UCHCOM_IFACE_INDEX,
                                           riface);
        if (err) {
                aprint_error("\n%s: failed to get interface: %s\n",
                        device_xname(sc->sc_dev), usbd_errstr(err));
                return -1;
        }

        return 0;
}

static int
find_endpoints(struct uchcom_softc *sc, struct uchcom_endpoints *endpoints)
{
        int i, bin=-1, bout=-1, intr=-1, isize=0;
        usb_interface_descriptor_t *id;
        usb_endpoint_descriptor_t *ed;

        id = usbd_get_interface_descriptor(sc->sc_iface);

        for (i = 0; i < id->bNumEndpoints; i++) {
                ed = usbd_interface2endpoint_descriptor(sc->sc_iface, i);
                if (ed == NULL) {
                        aprint_error_dev(sc->sc_dev,
                            "no endpoint descriptor for %d\n", i);
                        return -1;
                }

                if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_IN &&
                    UE_GET_XFERTYPE(ed->bmAttributes) == UE_INTERRUPT) {
                        intr = ed->bEndpointAddress;
                        isize = UGETW(ed->wMaxPacketSize);
                } else if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_IN &&
                           UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK) {
                        bin = ed->bEndpointAddress;
                } else if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_OUT &&
                           UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK) {
                        bout = ed->bEndpointAddress;
                }
        }

        if (intr == -1 || bin == -1 || bout == -1) {
                if (intr == -1) {
                        aprint_error_dev(sc->sc_dev,
                            "no interrupt end point\n");
                }
                if (bin == -1) {
                        aprint_error_dev(sc->sc_dev,
                            "no data bulk in end point\n");
                }
                if (bout == -1) {
                        aprint_error_dev(sc->sc_dev,
                            "no data bulk out end point\n");
                }
                return -1;
        }
        if (isize < UCHCOM_INTR_LEAST) {
                aprint_error_dev(sc->sc_dev, "intr pipe is too short\n");
                return -1;
        }

        DPRINTF(("%s: bulkin=%d, bulkout=%d, intr=%d, isize=%d\n",
                 device_xname(sc->sc_dev), bin, bout, intr, isize));

        endpoints->ep_intr = intr;
        endpoints->ep_intr_size = isize;
        endpoints->ep_bulkin = bin;
        endpoints->ep_bulkout = bout;

        return 0;
}


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

static __inline usbd_status
generic_control_out(struct uchcom_softc *sc, uint8_t reqno,
                    uint16_t value, uint16_t index)
{
        usb_device_request_t req;

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

        return usbd_do_request(sc->sc_udev, &req, 0);
}

static __inline usbd_status
generic_control_in(struct uchcom_softc *sc, uint8_t reqno,
                   uint16_t value, uint16_t index, void *buf, int buflen,
                   int *actlen)
{
        usb_device_request_t req;

        req.bmRequestType = UT_READ_VENDOR_DEVICE;
        req.bRequest = reqno;
        USETW(req.wValue, value);
        USETW(req.wIndex, index);
        USETW(req.wLength, (uint16_t)buflen);

        return usbd_do_request_flags(sc->sc_udev, &req, buf,
                                     USBD_SHORT_XFER_OK, actlen,
                                     USBD_DEFAULT_TIMEOUT);
}

static __inline usbd_status
write_reg(struct uchcom_softc *sc,
          uint8_t reg1, uint8_t val1, uint8_t reg2, uint8_t val2)
{
        DPRINTF(("%s: write reg 0x%02X<-0x%02X, 0x%02X<-0x%02X\n",
                 device_xname(sc->sc_dev),
                 (unsigned)reg1, (unsigned)val1,
                 (unsigned)reg2, (unsigned)val2));
        return generic_control_out(
                sc, UCHCOM_REQ_WRITE_REG,
                reg1|((uint16_t)reg2<<8), val1|((uint16_t)val2<<8));
}

static __inline usbd_status
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];
        usbd_status err;
        int actin;

        err = generic_control_in(
                sc, UCHCOM_REQ_READ_REG,
                reg1|((uint16_t)reg2<<8), 0, buf, sizeof(buf), &actin);
        if (err)
                return err;

        DPRINTF(("%s: read reg 0x%02X->0x%02X, 0x%02X->0x%02X\n",
                 device_xname(sc->sc_dev),
                 (unsigned)reg1, (unsigned)buf[0],
                 (unsigned)reg2, (unsigned)buf[1]));

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

        return USBD_NORMAL_COMPLETION;
}

static __inline usbd_status
get_version(struct uchcom_softc *sc, uint8_t *rver)
{
        uint8_t buf[UCHCOM_INPUT_BUF_SIZE];
        usbd_status err;
        int actin;

        err = generic_control_in(
                sc, UCHCOM_REQ_GET_VERSION, 0, 0, buf, sizeof(buf), &actin);
        if (err)
                return err;

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

        return USBD_NORMAL_COMPLETION;
}

static __inline usbd_status
get_status(struct uchcom_softc *sc, uint8_t *rval)
{
        return read_reg(sc, UCHCOM_REG_STAT1, rval, UCHCOM_REG_STAT2, NULL);
}

static __inline usbd_status
set_dtrrts_10(struct uchcom_softc *sc, uint8_t val)
{
        return write_reg(sc, UCHCOM_REG_STAT1, val, UCHCOM_REG_STAT1, val);
}

static __inline usbd_status
set_dtrrts_20(struct uchcom_softc *sc, uint8_t val)
{
        return generic_control_out(sc, UCHCOM_REQ_SET_DTRRTS, val, 0);
}


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

static int
update_version(struct uchcom_softc *sc)
{
        usbd_status err;

        err = get_version(sc, &sc->sc_version);
        if (err) {
                device_printf(sc->sc_dev, "cannot get version: %s\n",
                    usbd_errstr(err));
                return EIO;
        }
        DPRINTF(("%s: update_version %d\n", device_xname(sc->sc_dev), sc->sc_version));

        return 0;
}

static void
convert_status(struct uchcom_softc *sc, uint8_t cur)
{
        sc->sc_dtr = !(cur & UCHCOM_DTR_MASK);
        sc->sc_rts = !(cur & UCHCOM_RTS_MASK);

        cur = ~cur & 0x0F;
        sc->sc_msr = (cur << 4) | ((sc->sc_msr >> 4) ^ cur);
}

static int
update_status(struct uchcom_softc *sc)
{
        usbd_status err;
        uint8_t cur;

        err = get_status(sc, &cur);
        if (err) {
                device_printf(sc->sc_dev,
                    "cannot update status: %s\n", usbd_errstr(err));
                return EIO;
        }
        convert_status(sc, cur);

        return 0;
}


static int
set_dtrrts(struct uchcom_softc *sc, int dtr, int rts)
{
        usbd_status err;
        uint8_t val = 0;

        if (dtr) val |= UCHCOM_DTR_MASK;
        if (rts) val |= UCHCOM_RTS_MASK;

        if (sc->sc_version < UCHCOM_VER_20)
                err = set_dtrrts_10(sc, ~val);
        else
                err = set_dtrrts_20(sc, ~val);

        if (err) {
                device_printf(sc->sc_dev, "cannot set DTR/RTS: %s\n",
                    usbd_errstr(err));
                return EIO;
        }

        return 0;
}

static int
set_break(struct uchcom_softc *sc, int onoff)
{
        usbd_status err;
        uint8_t brk, lcr;

        err = read_reg(sc, UCHCOM_REG_BREAK, &brk, UCHCOM_REG_LCR, &lcr);
        if (err)
                return EIO;
        if (onoff) {
                /* on - clear bits */
                brk &= ~UCHCOM_BREAK_MASK;
                lcr &= ~UCHCOM_LCR_TXE;
        } else {
                /* off - set bits */
                brk |= UCHCOM_BREAK_MASK;
                lcr |= UCHCOM_LCR_TXE;
        }
        err = write_reg(sc, UCHCOM_REG_BREAK, brk, UCHCOM_REG_LCR, lcr);
        if (err)
                return EIO;

        return 0;
}

static int
calc_divider_settings(struct uchcom_divider *dp, uint32_t rate)
{
/*
 * combined with rates4x[] defined above, this routine generates,
 *   1200: prescale = 1/0x1, divisor = 178/0xb2
 *   2400: prescale = 1/0x1, divisor = 217/0xd9
 *   4800: prescale = 2/0x2, divisor = 100/0x64
 *   9600: prescale = 2/0x2, divisor = 178/0xb2
 *  19200: prescale = 2/0x2, divisor = 217/0xd9
 *  38400: prescale = 3/0x3, divisor = 100/0x64
 *  57600: prescale = 2/0x2, divisor = 243/0xf3
 * 115200: prescale = 3/0x3, divisor = 204/0xcc
 * 921600: prescale = 7/0x7, divisor = 243/0xf3
 * 500000: prescale = 3/0x3, divisor = 244/0xf4
 * 1000000: prescale = 3/0x3, divisor = 250/0xfa
 * 1500000: prescale = 3/0x3, divisor = 252/0xfc
 * 2000000: prescale = 3/0x3, divisor = 253/0xfd
 * 2500000: unsupported
 * 3000000: prescale = 3/0x3, divisor = 254/0xfe
 */
        size_t i;
        uint32_t best, div, pre;
        const uint32_t rate4x = rate * 4U;

        if (rate == 0 || rate > 3000000)
                return -1;

        pre = __arraycount(rates4x);
        best = UINT32_MAX;

        for (i = 0; i < __arraycount(rates4x); i++) {
                uint32_t score, try;
                try = rates4x[i] * 2 / rate4x;
                try = (try / 2) + (try & 1);
                if (try < 2)
                        continue;
                if (try > 255)
                        try = 255;
                score = abs((int)rate4x - rates4x[i] / try);
                if (score < best) {
                        best = score;
                        pre = i;
                        div = try;
                }
        }

        if (pre >= __arraycount(rates4x))
                return -1;
        if ((rates4x[pre] / div / 4) < (rate * 99 / 100))
                return -1;
        if ((rates4x[pre] / div / 4) > (rate * 101 / 100))
                return -1;

        dp->dv_prescaler = pre;
        dp->dv_div = 256 - div;

        return 0;
}

static int
set_dte_rate(struct uchcom_softc *sc, uint32_t rate)
{
        usbd_status err;
        struct uchcom_divider dv;

        if (calc_divider_settings(&dv, rate))
                return EINVAL;

        if ((err = write_reg(sc,
                             UCHCOM_REG_BPS_PRE,
                             dv.dv_prescaler | UCHCOM_BPS_PRE_IMM,
                             UCHCOM_REG_BPS_DIV, dv.dv_div))) {
                device_printf(sc->sc_dev, "cannot set DTE rate: %s\n",
                    usbd_errstr(err));
                return EIO;
        }

        return 0;
}

static int
set_line_control(struct uchcom_softc *sc, tcflag_t cflag)
{
        usbd_status err;
        uint8_t lcr = 0, lcr2 = 0;

        err = read_reg(sc, UCHCOM_REG_LCR, &lcr, UCHCOM_REG_LCR2, &lcr2);
        if (err) {
                device_printf(sc->sc_dev, "cannot get LCR: %s\n",
                    usbd_errstr(err));
                return EIO;
        }

        lcr = UCHCOM_LCR_RXE | UCHCOM_LCR_TXE;

        switch (ISSET(cflag, CSIZE)) {
        case CS5:
                lcr |= UCHCOM_LCR_CS5;
                break;
        case CS6:
                lcr |= UCHCOM_LCR_CS6;
                break;
        case CS7:
                lcr |= UCHCOM_LCR_CS7;
                break;
        case CS8:
                lcr |= UCHCOM_LCR_CS8;
                break;
        }

        if (ISSET(cflag, PARENB)) {
                lcr |= UCHCOM_LCR_PARENB;
                if (!ISSET(cflag, PARODD))
                        lcr |= UCHCOM_LCR_PAREVEN;
        }

        if (ISSET(cflag, CSTOPB)) {
                lcr |= UCHCOM_LCR_STOPB;
        }

        err = write_reg(sc, UCHCOM_REG_LCR, lcr, UCHCOM_REG_LCR2, lcr2);
        if (err) {
                device_printf(sc->sc_dev, "cannot set LCR: %s\n",
                    usbd_errstr(err));
                return EIO;
        }

        return 0;
}

static int
clear_chip(struct uchcom_softc *sc)
{
        usbd_status err;

        DPRINTF(("%s: clear\n", device_xname(sc->sc_dev)));
        err = generic_control_out(sc, UCHCOM_REQ_RESET, 0, 0);
        if (err) {
                device_printf(sc->sc_dev, "cannot clear: %s\n",
                    usbd_errstr(err));
                return EIO;
        }
        /*
         * this REQ_RESET call ends up with
         * LCR=0xc0 (8N1)
         * PRE=0x02, DIV=0xd9 (19200)
         */
        return 0;
}

static int
setup_comm(struct uchcom_softc *sc)
{
        int ret;

        ret = update_version(sc);
        if (ret)
                return ret;

        ret = clear_chip(sc);
        if (ret)
                return ret;

        ret = set_dte_rate(sc, TTYDEF_SPEED);
        if (ret)
                return ret;

        ret = set_line_control(sc, CS8);
        if (ret)
                return ret;

        ret = update_status(sc);
        if (ret)
                return ret;

        sc->sc_dtr = sc->sc_rts = 1;
        ret = set_dtrrts(sc, sc->sc_dtr, sc->sc_rts);
        if (ret)
                return ret;

        return 0;
}

static int
setup_intr_pipe(struct uchcom_softc *sc)
{
        usbd_status err;

        if (sc->sc_intr_endpoint != -1 && sc->sc_intr_pipe == NULL) {
                sc->sc_intr_buf = kmem_alloc(sc->sc_intr_size, KM_SLEEP);
                err = usbd_open_pipe_intr(sc->sc_iface,
                                          sc->sc_intr_endpoint,
                                          USBD_SHORT_XFER_OK,
                                          &sc->sc_intr_pipe, sc,
                                          sc->sc_intr_buf,
                                          sc->sc_intr_size,
                                          uchcom_intr, USBD_DEFAULT_INTERVAL);
                if (err) {
                        device_printf(sc->sc_dev,
                            "cannot open interrupt pipe: %s\n",
                            usbd_errstr(err));
                        return EIO;
                }
        }
        return 0;
}

static void
close_intr_pipe(struct uchcom_softc *sc)
{

        if (sc->sc_intr_pipe != NULL) {
                usbd_abort_pipe(sc->sc_intr_pipe);
                usbd_close_pipe(sc->sc_intr_pipe);
                sc->sc_intr_pipe = NULL;
        }
        if (sc->sc_intr_buf != NULL) {
                kmem_free(sc->sc_intr_buf, sc->sc_intr_size);
                sc->sc_intr_buf = NULL;
        }
}


/* ----------------------------------------------------------------------
 * methods for ucom
 */
static void
uchcom_get_status(void *arg, int portno, u_char *rlsr, u_char *rmsr)
{
        struct uchcom_softc *sc = arg;

        if (sc->sc_dying)
                return;

        *rlsr = sc->sc_lsr;
        *rmsr = sc->sc_msr;
}

static void
uchcom_set(void *arg, int portno, int reg, int onoff)
{
        struct uchcom_softc *sc = arg;

        if (sc->sc_dying)
                return;

        switch (reg) {
        case UCOM_SET_DTR:
                sc->sc_dtr = !!onoff;
                set_dtrrts(sc, sc->sc_dtr, sc->sc_rts);
                break;
        case UCOM_SET_RTS:
                sc->sc_rts = !!onoff;
                set_dtrrts(sc, sc->sc_dtr, sc->sc_rts);
                break;
        case UCOM_SET_BREAK:
                set_break(sc, onoff);
                break;
        }
}

static int
uchcom_param(void *arg, int portno, struct termios *t)
{
        struct uchcom_softc *sc = arg;
        int ret;

        if (sc->sc_dying)
                return EIO;

        ret = set_line_control(sc, t->c_cflag);
        if (ret)
                return ret;

        ret = set_dte_rate(sc, t->c_ospeed);
        if (ret)
                return ret;

        return 0;
}

static int
uchcom_open(void *arg, int portno)
{
        int ret;
        struct uchcom_softc *sc = arg;

        if (sc->sc_dying)
                return EIO;

        ret = setup_intr_pipe(sc);
        if (ret)
                return ret;

        ret = setup_comm(sc);
        if (ret)
                return ret;

        return 0;
}

static void
uchcom_close(void *arg, int portno)
{
        struct uchcom_softc *sc = arg;

        if (sc->sc_dying)
                return;

        close_intr_pipe(sc);
}


/* ----------------------------------------------------------------------
 * callback when the modem status is changed.
 */
static void
uchcom_intr(struct usbd_xfer *xfer, void * priv,
            usbd_status status)
{
        struct uchcom_softc *sc = priv;
        u_char *buf = sc->sc_intr_buf;

        if (sc->sc_dying)
                return;

        if (status != USBD_NORMAL_COMPLETION) {
                if (status == USBD_NOT_STARTED || status == USBD_CANCELLED)
                        return;

                DPRINTF(("%s: abnormal status: %s\n",
                         device_xname(sc->sc_dev), usbd_errstr(status)));
                usbd_clear_endpoint_stall_async(sc->sc_intr_pipe);
                return;
        }
        DPRINTF(("%s: intr: 0x%02X 0x%02X 0x%02X 0x%02X "
                 "0x%02X 0x%02X 0x%02X 0x%02X\n",
                 device_xname(sc->sc_dev),
                 (unsigned)buf[0], (unsigned)buf[1],
                 (unsigned)buf[2], (unsigned)buf[3],
                 (unsigned)buf[4], (unsigned)buf[5],
                 (unsigned)buf[6], (unsigned)buf[7]));

        convert_status(sc, buf[UCHCOM_INTR_STAT1]);
        ucom_status_change(device_private(sc->sc_subdev));
}