xref: /netbsd-src/sys/dev/usb/uchcom.c (revision c7fb772b85b2b5d4cfb282f868f454b4701534fd)

/*	$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));
}