/*      $NetBSD: zs.c,v 1.82 2024/07/06 10:09:15 andvar Exp $   */

/*
* Copyright (c) 1992, 1993
*      The Regents of the University of California.  All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Lawrence Berkeley Laboratory.
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
*      @(#)zs.c        8.1 (Berkeley) 7/19/93
*/

/*-
* Copyright (c) 1995 The NetBSD Foundation, Inc. (Atari modifications)
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Leo Weppelman.
*
* 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.
*/

/*
* Zilog Z8530 (ZSCC) driver.
*
* Runs two tty ports (modem2 and serial2) on zs0.
*
* This driver knows far too much about chip to usage mappings.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: zs.c,v 1.82 2024/07/06 10:09:15 andvar Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/device.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/kmem.h>
#include <sys/tty.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/kauth.h>

#include <machine/cpu.h>
#include <machine/iomap.h>
#include <machine/scu.h>
#include <machine/mfp.h>
#include <atari/dev/ym2149reg.h>

#include <dev/ic/z8530reg.h>
#include <atari/dev/zsvar.h>

#include "ioconf.h"

#include "zs.h"
#if NZS > 1
#error "This driver supports only 1 85C30!"
#endif

#if NZS > 0

#define PCLK    (8053976)       /* PCLK pin input clock rate */
#define PCLK_HD (9600 * 1536)   /* PCLK on Hades pin input clock rate */

#define splzs   spl5

/*
* Software state per found chip.
*/
struct zs_softc {
       device_t sc_dev;                /* base device */
       struct zs_chanstate *sc_cs[2];  /* chan A and B software state */

       struct zs_chanstate sc_cs_store[2];
       void *sc_sicookie;              /* for callback */
};

/*
* Define the registers for a closed port
*/
static uint8_t zs_init_regs[16] = {
/*  0 */        0,
/*  1 */        0,
/*  2 */        0x60,
/*  3 */        0,
/*  4 */        0,
/*  5 */        0,
/*  6 */        0,
/*  7 */        0,
/*  8 */        0,
/*  9 */        ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT,
/* 10 */        ZSWR10_NRZ,
/* 11 */        ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
/* 12 */        0,
/* 13 */        0,
/* 14 */        ZSWR14_BAUD_FROM_PCLK | ZSWR14_BAUD_ENA,
/* 15 */        0
};

/*
* Define the machine dependent clock frequencies
* If BRgen feeds sender/receiver we always use a
* divisor 16; therefore the division by 16 can as
* well be done here.
*/
static const u_long zs_freqs_tt[] = {
       /*
        * Atari TT, RTxCB is generated by TT-MFP timer C,
        * which is set to 307.2 kHz during initialisation
        * and never changed afterwards.
        */
       PCLK/16,        /* BRgen, PCLK,  divisor 16     */
        229500,        /* BRgen, RTxCA, divisor 16     */
       3672000,        /* RTxCA, from PCLK4            */
             0,        /* TRxCA, external              */

       PCLK/16,        /* BRgen, PCLK,  divisor 16     */
         19200,        /* BRgen, RTxCB, divisor 16     */
        307200,        /* RTxCB, from TT-MFP TCO       */
       2457600         /* TRxCB, from BCLK             */
};

static const u_long zs_freqs_falcon[] = {
       /*
        * Atari Falcon, XXX no specs available, this might be wrong
        */
       PCLK/16,        /* BRgen, PCLK,  divisor 16     */
        229500,        /* BRgen, RTxCA, divisor 16     */
       3672000,        /* RTxCA, ???                   */
             0,        /* TRxCA, external              */

       PCLK/16,        /* BRgen, PCLK,  divisor 16     */
        229500,        /* BRgen, RTxCB, divisor 16     */
       3672000,        /* RTxCB, ???                   */
       2457600         /* TRxCB, ???                   */
};

static const u_long zs_freqs_hades[] = {
       /*
        * XXX: Channel-A unchecked!!!!!
        */
    PCLK_HD/16,        /* BRgen, PCLK,  divisor 16     */
        229500,        /* BRgen, RTxCA, divisor 16     */
       3672000,        /* RTxCA, from PCLK4            */
             0,        /* TRxCA, external              */

    PCLK_HD/16,        /* BRgen, PCLK,  divisor 16     */
        235550,        /* BRgen, RTxCB, divisor 16     */
       3768800,        /* RTxCB, 3.7688MHz             */
       3768800         /* TRxCB, 3.7688MHz             */
};

static const u_long zs_freqs_generic[] = {
       /*
        * other machines, assume only PCLK is available
        */
       PCLK/16,        /* BRgen, PCLK,  divisor 16     */
             0,        /* BRgen, RTxCA, divisor 16     */
             0,        /* RTxCA, unknown               */
             0,        /* TRxCA, unknown               */

       PCLK/16,        /* BRgen, PCLK,  divisor 16     */
             0,        /* BRgen, RTxCB, divisor 16     */
             0,        /* RTxCB, unknown               */
             0         /* TRxCB, unknown               */
};
static const u_long *zs_frequencies;

/* Definition of the driver for autoconfig. */
static int      zsmatch(device_t, cfdata_t, void *);
static void     zsattach(device_t, device_t, void *);

CFATTACH_DECL_NEW(zs, sizeof(struct zs_softc),
   zsmatch, zsattach, NULL, NULL);

/* {b,c}devsw[] function prototypes */
static dev_type_open(zsopen);
static dev_type_close(zsclose);
static dev_type_read(zsread);
static dev_type_write(zswrite);
static dev_type_ioctl(zsioctl);
static dev_type_stop(zsstop);
static dev_type_tty(zstty);
static dev_type_poll(zspoll);

const struct cdevsw zs_cdevsw = {
       .d_open = zsopen,
       .d_close = zsclose,
       .d_read = zsread,
       .d_write = zswrite,
       .d_ioctl = zsioctl,
       .d_stop = zsstop,
       .d_tty = zstty,
       .d_poll = zspoll,
       .d_mmap = nommap,
       .d_kqfilter = ttykqfilter,
       .d_discard = nodiscard,
       .d_flag = D_TTY
};

/* Interrupt handlers. */
static int      zshard(void *);
static int      zssoft(void *);
static int      zsrint(struct zs_chanstate *, struct zschan *);
static int      zsxint(struct zs_chanstate *, struct zschan *);
static int      zssint(struct zs_chanstate *, struct zschan *);

/* Routines called from other code. */
static void     zsstart(struct tty *);

/* Routines purely local to this driver. */
static void     zsoverrun(int, long *, const char *);
static int      zsparam(struct tty *, struct termios *);
static int      zsbaudrate(int, int, int *, int *, int *, int *);
static int      zs_modem(struct zs_chanstate *, int, int);
static void     zs_loadchannelregs(struct zschan *, uint8_t *);
static void     zs_shutdown(struct zs_chanstate *);

static int
zsmatch(device_t parent, cfdata_t cf, void *aux)
{
       static int zs_matched = 0;

       if (strcmp("zs", aux) || zs_matched)
               return 0;
       zs_matched = 1;
       return 1;
}

/*
* Attach a found zs.
*/
static void
zsattach(device_t parent, device_t self, void *aux)
{
       struct zs_softc *sc;
       struct zsdevice *zs;
       struct zschan *zc;
       struct zs_chanstate *cs;
       int channel;

       sc = device_private(self);
       sc->sc_dev = self;

       printf(": serial2 on channel a and modem2 on channel b\n");

       zs = (struct zsdevice *)AD_SCC;

       for (channel = 0; channel < 2; channel++) {
               cs = &sc->sc_cs_store[channel];
               sc->sc_cs[channel] = cs;

               cs->cs_unit = channel;
               cs->cs_zc = zc =
                   (channel == 0) ?  &zs->zs_chan_a : &zs->zs_chan_b;
               /*
                * Get the command register into a known state.
                */
               (void)zc->zc_csr;
               (void)zc->zc_csr;

               /*
                * Do a hardware reset.
                */
               if (channel == 0) {
                       ZS_WRITE(zc, 9, ZSWR9_HARD_RESET);
                       delay(50000);   /* enough ? */
                       ZS_WRITE(zc, 9, 0);
               }

               /*
                * Initialize channel
                */
               zs_loadchannelregs(zc, zs_init_regs);
       }

       if (machineid & ATARI_TT) {
               /*
                * initialise TT-MFP timer C: 307200Hz
                * timer C and D share one control register:
                *      bits 0-2 control timer D
                *      bits 4-6 control timer C
                */
               int cr = MFP2->mf_tcdcr & 7;
               MFP2->mf_tcdcr = cr;            /* stop timer C  */
               MFP2->mf_tcdr  = 1;             /* counter 1     */
               cr |= T_Q004 << 4;              /* divisor 4     */
               MFP2->mf_tcdcr = cr;            /* start timer C */
               /*
                * enable scc related interrupts
                */
               SCU->vme_mask |= SCU_SCC;

               zs_frequencies = zs_freqs_tt;
       } else if (machineid & ATARI_FALCON) {
               zs_frequencies = zs_freqs_falcon;
       } else if (machineid & ATARI_HADES) {
               zs_frequencies = zs_freqs_hades;
       } else {
               zs_frequencies = zs_freqs_generic;
       }

       if (intr_establish(36, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Rx chan B)\n");
       if (intr_establish(32, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Tx empty chan B)\n");
       if (intr_establish(34, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Ext./Status chan B)\n");
       if (intr_establish(38, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Special Rx cond. chan B)\n");
       if (intr_establish(44, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Rx chan A)\n");
       if (intr_establish(40, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Tx empty chan A)\n");
       if (intr_establish(42, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Ext./Status chan A)\n");
       if (intr_establish(46, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
               aprint_error_dev(self,
                   "Can't establish interrupt (Special Rx cond. chan A)\n");

       sc->sc_sicookie = softint_establish(SOFTINT_SERIAL,
           (void (*)(void *))zssoft, sc);
}

/*
* Open a zs serial port.
*/
static int
zsopen(dev_t dev, int flags, int mode, struct lwp *l)
{
       struct tty *tp;
       struct zs_chanstate *cs;
       struct zs_softc *sc;
       int unit = ZS_UNIT(dev);
       int zs = unit >> 1;
       int error, s;

       sc = device_lookup_private(&zs_cd, zs);
       if (sc == NULL)
               return ENXIO;
       cs = sc->sc_cs[unit & 1];

       /*
        * When port A (ser02) is selected on the TT, make sure
        * the port is enabled.
        */
       if ((machineid & ATARI_TT) && !(unit & 1))
               ym2149_ser2(1);

       if (cs->cs_rbuf == NULL) {
               cs->cs_rbuf = kmem_alloc(ZLRB_RING_SIZE * sizeof(int),
                   KM_SLEEP);
       }

       tp = cs->cs_ttyp;
       if (tp == NULL) {
               cs->cs_ttyp = tp = tty_alloc();
               tty_attach(tp);
               tp->t_dev   = dev;
               tp->t_oproc = zsstart;
               tp->t_param = zsparam;
       }

       if (kauth_authorize_device_tty(l->l_cred, KAUTH_DEVICE_TTY_OPEN, tp))
               return EBUSY;

       s  = spltty();

       /*
        * Do the following iff this is a first open.
        */
       if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
               if (tp->t_ispeed == 0) {
                       tp->t_iflag = TTYDEF_IFLAG;
                       tp->t_oflag = TTYDEF_OFLAG;
                       tp->t_cflag = TTYDEF_CFLAG;
                       tp->t_lflag = TTYDEF_LFLAG;
                       tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
               }
               ttychars(tp);
               ttsetwater(tp);

               (void)zsparam(tp, &tp->t_termios);

               /*
                * Turn on DTR.  We must always do this, even if carrier is not
                * present, because otherwise we'd have to use TIOCSDTR
                * immediately after setting CLOCAL, which applications do not
                * expect.  We always assert DTR while the device is open
                * unless explicitly requested to deassert it.
                */
               zs_modem(cs, ZSWR5_RTS|ZSWR5_DTR, DMSET);
               /* May never get a status intr. if DCD already on. -gwr */
               if (((cs->cs_rr0 = cs->cs_zc->zc_csr) & ZSRR0_DCD) != 0)
                       tp->t_state |= TS_CARR_ON;
               if (cs->cs_softcar)
                       tp->t_state |= TS_CARR_ON;
       }

       splx(s);

       error = ttyopen(tp, ZS_DIALOUT(dev), (flags & O_NONBLOCK));
       if (error)
               goto bad;

       error = tp->t_linesw->l_open(dev, tp);
       if (error)
               goto bad;
       return 0;

bad:
       if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
               /*
                * We failed to open the device, and nobody else had it opened.
                * Clean up the state as appropriate.
                */
               zs_shutdown(cs);
       }
       return error;
}

/*
* Close a zs serial port.
*/
static int
zsclose(dev_t dev, int flags, int mode, struct lwp *l)
{
       struct zs_chanstate *cs;
       struct tty *tp;
       struct zs_softc *sc;
       int unit = ZS_UNIT(dev);

       sc = device_lookup_private(&zs_cd, unit >> 1);
       cs = sc->sc_cs[unit & 1];
       tp = cs->cs_ttyp;

       tp->t_linesw->l_close(tp, flags);
       ttyclose(tp);

       if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
               /*
                * Although we got a last close, the device may still be in
                * use; e.g. if this was the dialout node, and there are still
                * processes waiting for carrier on the non-dialout node.
                */
               zs_shutdown(cs);
       }
       return 0;
}

/*
* Read/write zs serial port.
*/
static int
zsread(dev_t dev, struct uio *uio, int flags)
{
       struct zs_chanstate *cs;
       struct zs_softc *sc;
       struct tty *tp;
       int unit;

       unit = ZS_UNIT(dev);
       sc   = device_lookup_private(&zs_cd, unit >> 1);
       cs   = sc->sc_cs[unit & 1];
       tp   = cs->cs_ttyp;

       return (*tp->t_linesw->l_read)(tp, uio, flags);
}

static int
zswrite(dev_t dev, struct uio *uio, int flags)
{
       struct zs_chanstate *cs;
       struct zs_softc *sc;
       struct tty *tp;
       int unit;

       unit = ZS_UNIT(dev);
       sc   = device_lookup_private(&zs_cd, unit >> 1);
       cs   = sc->sc_cs[unit & 1];
       tp   = cs->cs_ttyp;

       return (*tp->t_linesw->l_write)(tp, uio, flags);
}

static int
zspoll(dev_t dev, int events, struct lwp *l)
{
       struct zs_chanstate *cs;
       struct zs_softc *sc;
       struct tty *tp;
       int unit;

       unit = ZS_UNIT(dev);
       sc   = device_lookup_private(&zs_cd, unit >> 1);
       cs   = sc->sc_cs[unit & 1];
       tp   = cs->cs_ttyp;

       return (*tp->t_linesw->l_poll)(tp, events, l);
}

static struct tty *
zstty(dev_t dev)
{
       struct zs_chanstate *cs;
       struct zs_softc *sc;
       int unit;

       unit = ZS_UNIT(dev);
       sc   = device_lookup_private(&zs_cd, unit >> 1);
       cs   = sc->sc_cs[unit & 1];
       return cs->cs_ttyp;
}

/*
* ZS hardware interrupt.  Scan all ZS channels.  NB: we know here that
* channels are kept in (A,B) pairs.
*
* Do just a little, then get out; set a software interrupt if more
* work is needed.
*
* We deliberately ignore the vectoring Zilog gives us, and match up
* only the number of `reset interrupt under service' operations, not
* the order.
*/

int
zshard(void *arg)
{
       struct zs_softc *sc;
       struct zs_chanstate *cs0, *cs1;
       struct zschan *zc;
       int intflags, v, i;
       uint8_t rr3;

       sc = arg;
       intflags = 0;
       cs0 = sc->sc_cs[0];
       cs1 = sc->sc_cs[1];

       do {
               intflags &= ~4;
               rr3 = ZS_READ(cs0->cs_zc, 3);
               if (rr3 & (ZSRR3_IP_A_RX | ZSRR3_IP_A_TX | ZSRR3_IP_A_STAT)) {
                       intflags |= 4 | 2;
                       zc = cs0->cs_zc;
                       i  = cs0->cs_rbput;
                       if ((rr3 & ZSRR3_IP_A_RX) != 0 &&
                           (v = zsrint(cs0, zc)) != 0) {
                               cs0->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
                               intflags |= 1;
                       }
                       if ((rr3 & ZSRR3_IP_A_TX) != 0 &&
                           (v = zsxint(cs0, zc)) != 0) {
                               cs0->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
                               intflags |= 1;
                       }
                       if ((rr3 & ZSRR3_IP_A_STAT) != 0 &&
                           (v = zssint(cs0, zc)) != 0) {
                               cs0->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
                               intflags |= 1;
                       }
                       cs0->cs_rbput = i;
               }
               if (rr3 & (ZSRR3_IP_B_RX | ZSRR3_IP_B_TX | ZSRR3_IP_B_STAT)) {
                       intflags |= 4 | 2;
                       zc = cs1->cs_zc;
                       i  = cs1->cs_rbput;
                       if ((rr3 & ZSRR3_IP_B_RX) != 0 &&
                           (v = zsrint(cs1, zc)) != 0) {
                               cs1->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
                               intflags |= 1;
                       }
                       if ((rr3 & ZSRR3_IP_B_TX) != 0 &&
                           (v = zsxint(cs1, zc)) != 0) {
                               cs1->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
                               intflags |= 1;
                       }
                       if ((rr3 & ZSRR3_IP_B_STAT) != 0 &&
                           (v = zssint(cs1, zc)) != 0) {
                               cs1->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
                               intflags |= 1;
                       }
                       cs1->cs_rbput = i;
               }
       } while (intflags & 4);

       if (intflags & 1)
               softint_schedule(sc->sc_sicookie);

       return intflags & 2;
}

static int
zsrint(struct zs_chanstate *cs, struct zschan *zc)
{
       int c;

       /*
        * First read the status, because read of the received char
        * destroy the status of this char.
        */
       c = ZS_READ(zc, 1);
       c |= (zc->zc_data << 8);

       /* clear receive error & interrupt condition */
       zc->zc_csr = ZSWR0_RESET_ERRORS;
       zc->zc_csr = ZSWR0_CLR_INTR;

       return ZRING_MAKE(ZRING_RINT, c);
}

static int
zsxint(struct zs_chanstate *cs, struct zschan *zc)
{
       int i = cs->cs_tbc;

       if (i == 0) {
               zc->zc_csr = ZSWR0_RESET_TXINT;
               zc->zc_csr = ZSWR0_CLR_INTR;
               return ZRING_MAKE(ZRING_XINT, 0);
       }
       cs->cs_tbc = i - 1;
       zc->zc_data = *cs->cs_tba++;
       zc->zc_csr = ZSWR0_CLR_INTR;
       return 0;
}

static int
zssint(struct zs_chanstate *cs, struct zschan *zc)
{
       int rr0;

       rr0 = zc->zc_csr;
       zc->zc_csr = ZSWR0_RESET_STATUS;
       zc->zc_csr = ZSWR0_CLR_INTR;
       /*
        * The chip's hardware flow control is, as noted in zsreg.h,
        * busted---if the DCD line goes low the chip shuts off the
        * receiver (!).  If we want hardware CTS flow control but do
        * not have it, and carrier is now on, turn HFC on; if we have
        * HFC now but carrier has gone low, turn it off.
        */
       if (rr0 & ZSRR0_DCD) {
               if (cs->cs_ttyp->t_cflag & CCTS_OFLOW &&
                   (cs->cs_creg[3] & ZSWR3_HFC) == 0) {
                       cs->cs_creg[3] |= ZSWR3_HFC;
                       ZS_WRITE(zc, 3, cs->cs_creg[3]);
               }
       } else {
               if (cs->cs_creg[3] & ZSWR3_HFC) {
                       cs->cs_creg[3] &= ~ZSWR3_HFC;
                       ZS_WRITE(zc, 3, cs->cs_creg[3]);
               }
       }
       return ZRING_MAKE(ZRING_SINT, rr0);
}

/*
* Print out a ring or fifo overrun error message.
*/
static void
zsoverrun(int unit, long *ptime, const char *what)
{
       time_t cur_sec = time_second;

       if (*ptime != cur_sec) {
               *ptime = cur_sec;
               log(LOG_WARNING, "zs%d%c: %s overrun\n", unit >> 1,
                   (unit & 1) + 'a', what);
       }
}

/*
* ZS software interrupt.  Scan all channels for deferred interrupts.
*/
int
zssoft(void *arg)
{
       struct zs_softc *sc;
       struct zs_chanstate *cs;
       struct zschan *zc;
       struct linesw *line;
       struct tty *tp;
       int chan, get, n, c, cc, s;
       int retval = 0;

       sc = arg;
       s = spltty();
       for (chan = 0; chan < 2; chan++) {
               cs = sc->sc_cs[chan];
               get = cs->cs_rbget;
again:
               n = cs->cs_rbput;       /* atomic                       */
               if (get == n)           /* nothing more on this line    */
                       continue;
               retval = 1;
               zc     = cs->cs_zc;
               tp     = cs->cs_ttyp;
               line   = tp->t_linesw;
               /*
                * Compute the number of interrupts in the receive ring.
                * If the count is overlarge, we lost some events, and
                * must advance to the first valid one.  It may get
                * overwritten if more data are arriving, but this is
                * too expensive to check and gains nothing (we already
                * lost out; all we can do at this point is trade one
                * kind of loss for another).
                */
               n -= get;
               if (n > ZLRB_RING_SIZE) {
                       zsoverrun(chan, &cs->cs_rotime, "ring");
                       get += n - ZLRB_RING_SIZE;
                       n    = ZLRB_RING_SIZE;
               }
               while (--n >= 0) {
                       /* race to keep ahead of incoming interrupts */
                       c = cs->cs_rbuf[get++ & ZLRB_RING_MASK];
                       switch (ZRING_TYPE(c)) {

                       case ZRING_RINT:
                               c = ZRING_VALUE(c);
                               if ((c & ZSRR1_DO) != 0)
                                       zsoverrun(chan, &cs->cs_fotime, "fifo");
                               cc = c >> 8;
                               if ((c & ZSRR1_FE) != 0)
                                       cc |= TTY_FE;
                               if ((c & ZSRR1_PE) != 0)
                                       cc |= TTY_PE;
                               line->l_rint(cc, tp);
                               break;

                       case ZRING_XINT:
                               /*
                                * Transmit done: change registers and resume,
                                * or clear BUSY.
                                */
                               if (cs->cs_heldchange) {
                                       int sps;

                                       sps = splzs();
                                       c = zc->zc_csr;
                                       if ((c & ZSRR0_DCD) == 0)
                                               cs->cs_preg[3] &= ~ZSWR3_HFC;
                                       memcpy((void *)cs->cs_creg,
                                           (void *)cs->cs_preg, 16);
                                       zs_loadchannelregs(zc, cs->cs_creg);
                                       splx(sps);
                                       cs->cs_heldchange = 0;
                                       if (cs->cs_heldtbc &&
                                           (tp->t_state & TS_TTSTOP) == 0) {
                                               cs->cs_tbc = cs->cs_heldtbc - 1;
                                               zc->zc_data = *cs->cs_tba++;
                                               goto again;
                                       }
                               }
                               tp->t_state &= ~TS_BUSY;
                               if ((tp->t_state & TS_FLUSH) != 0)
                                       tp->t_state &= ~TS_FLUSH;
                               else
                                       ndflush(&tp->t_outq,
                                           cs->cs_tba - tp->t_outq.c_cf);
                               line->l_start(tp);
                               break;

                       case ZRING_SINT:
                               /*
                                * Status line change.  HFC bit is run in
                                * hardware interrupt, to avoid locking
                                * at splzs here.
                                */
                               c = ZRING_VALUE(c);
                               if (((c ^ cs->cs_rr0) & ZSRR0_DCD) != 0) {
                                       cc = (c & ZSRR0_DCD) != 0;
                                       if (line->l_modem(tp, cc) == 0)
                                               zs_modem(cs,
                                                   ZSWR5_RTS | ZSWR5_DTR,
                                                   cc ? DMBIS : DMBIC);
                               }
                               cs->cs_rr0 = c;
                               break;

                       default:
                               log(LOG_ERR, "zs%d%c: bad ZRING_TYPE (%x)\n",
                                   chan >> 1, (chan & 1) + 'a', c);
                               break;
                       }
               }
               cs->cs_rbget = get;
               goto again;
       }
       splx(s);
       return retval;
}

static int
zsioctl(dev_t dev, u_long cmd, void * data, int flag, struct lwp *l)
{
       int unit = ZS_UNIT(dev);
       struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
       struct zs_chanstate *cs = sc->sc_cs[unit & 1];
       struct tty *tp = cs->cs_ttyp;
       int error, s;

       error = tp->t_linesw->l_ioctl(tp, cmd, data, flag, l);
       if (error != EPASSTHROUGH)
               return error;

       error = ttioctl(tp, cmd, data, flag, l);
       if (error !=EPASSTHROUGH)
               return error;

       switch (cmd) {
       case TIOCSBRK:
               s = splzs();
               cs->cs_preg[5] |= ZSWR5_BREAK;
               cs->cs_creg[5] |= ZSWR5_BREAK;
               ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
               splx(s);
               break;
       case TIOCCBRK:
               s = splzs();
               cs->cs_preg[5] &= ~ZSWR5_BREAK;
               cs->cs_creg[5] &= ~ZSWR5_BREAK;
               ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
               splx(s);
               break;
       case TIOCGFLAGS: {
               int bits = 0;

               if (cs->cs_softcar)
                       bits |= TIOCFLAG_SOFTCAR;
               if ((cs->cs_creg[15] & ZSWR15_DCD_IE) != 0)
                       bits |= TIOCFLAG_CLOCAL;
               if ((cs->cs_creg[3] & ZSWR3_HFC) != 0)
                       bits |= TIOCFLAG_CRTSCTS;
               *(int *)data = bits;
               break;
       }
       case TIOCSFLAGS: {
               int userbits = 0;

               error = kauth_authorize_device_tty(l->l_cred,
                   KAUTH_DEVICE_TTY_PRIVSET, tp);
               if (error != 0)
                       return EPERM;

               userbits = *(int *)data;

               /*
                * can have `local' or `softcar', and `rtscts' or `mdmbuf'
                # defaulting to software flow control.
                */
               if ((userbits & TIOCFLAG_SOFTCAR) != 0 &&
                   (userbits & TIOCFLAG_CLOCAL) != 0)
                       return EINVAL;
               if ((userbits & TIOCFLAG_MDMBUF) != 0)
                       /* don't support this (yet?) */
                       return ENODEV;

               s = splzs();
               if ((userbits & TIOCFLAG_SOFTCAR) != 0) {
                       cs->cs_softcar = 1;     /* turn on softcar */
                       cs->cs_preg[15] &= ~ZSWR15_DCD_IE; /* turn off dcd */
                       cs->cs_creg[15] &= ~ZSWR15_DCD_IE;
                       ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
               } else if ((userbits & TIOCFLAG_CLOCAL) != 0) {
                       cs->cs_softcar = 0;     /* turn off softcar */
                       cs->cs_preg[15] |= ZSWR15_DCD_IE; /* turn on dcd */
                       cs->cs_creg[15] |= ZSWR15_DCD_IE;
                       ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
                       tp->t_termios.c_cflag |= CLOCAL;
               }
               if ((userbits & TIOCFLAG_CRTSCTS) != 0) {
                       cs->cs_preg[15] |= ZSWR15_CTS_IE;
                       cs->cs_creg[15] |= ZSWR15_CTS_IE;
                       ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
                       cs->cs_preg[3] |= ZSWR3_HFC;
                       cs->cs_creg[3] |= ZSWR3_HFC;
                       ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
                       tp->t_termios.c_cflag |= CRTSCTS;
               } else {
                       /* no mdmbuf, so we must want software flow control */
                       cs->cs_preg[15] &= ~ZSWR15_CTS_IE;
                       cs->cs_creg[15] &= ~ZSWR15_CTS_IE;
                       ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
                       cs->cs_preg[3] &= ~ZSWR3_HFC;
                       cs->cs_creg[3] &= ~ZSWR3_HFC;
                       ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
                       tp->t_termios.c_cflag &= ~CRTSCTS;
               }
               splx(s);
               break;
       }
       case TIOCSDTR:
               zs_modem(cs, ZSWR5_DTR, DMBIS);
               break;
       case TIOCCDTR:
               zs_modem(cs, ZSWR5_DTR, DMBIC);
               break;
       case TIOCMGET:
               zs_modem(cs, 0, DMGET);
               break;
       case TIOCMSET:
       case TIOCMBIS:
       case TIOCMBIC:
       default:
               return EPASSTHROUGH;
       }
       return 0;
}

/*
* Start or restart transmission.
*/
static void
zsstart(struct tty *tp)
{
       struct zs_chanstate *cs;
       int s, nch;
       int unit = ZS_UNIT(tp->t_dev);
       struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);

       cs = sc->sc_cs[unit & 1];
       s  = spltty();

       /*
        * If currently active or delaying, no need to do anything.
        */
       if ((tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP)) != 0)
               goto out;

       /*
        * If there are sleepers, and output has drained below low
        * water mark, awaken.
        */
       ttypull(tp);

       nch = ndqb(&tp->t_outq, 0);     /* XXX */
       if (nch) {
               char *p = tp->t_outq.c_cf;

               /* mark busy, enable tx done interrupts, & send first byte */
               tp->t_state |= TS_BUSY;
               (void)splzs();
               cs->cs_preg[1] |= ZSWR1_TIE;
               cs->cs_creg[1] |= ZSWR1_TIE;
               ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
               cs->cs_zc->zc_data = *p;
               cs->cs_tba = p + 1;
               cs->cs_tbc = nch - 1;
       } else {
               /*
                * Nothing to send, turn off transmit done interrupts.
                * This is useful if something is doing polled output.
                */
               (void)splzs();
               cs->cs_preg[1] &= ~ZSWR1_TIE;
               cs->cs_creg[1] &= ~ZSWR1_TIE;
               ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
       }
out:
       splx(s);
}

/*
* Stop output, e.g., for ^S or output flush.
*/
static void
zsstop(struct tty *tp, int flag)
{
       struct zs_chanstate *cs;
       int s, unit = ZS_UNIT(tp->t_dev);
       struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);

       cs = sc->sc_cs[unit & 1];
       s  = splzs();
       if ((tp->t_state & TS_BUSY) != 0) {
               /*
                * Device is transmitting; must stop it.
                */
               cs->cs_tbc = 0;
               if ((tp->t_state & TS_TTSTOP) == 0)
                       tp->t_state |= TS_FLUSH;
       }
       splx(s);
}

static void
zs_shutdown(struct zs_chanstate *cs)
{
       struct tty *tp = cs->cs_ttyp;
       int s;

       s = splzs();

       /*
        * Hang up if necessary.  Wait a bit, so the other side has time to
        * notice even if we immediately open the port again.
        */
       if ((tp->t_cflag & HUPCL) != 0) {
               zs_modem(cs, 0, DMSET);
               (void)tsleep((void *)cs, TTIPRI, ttclos, hz);
       }

       /* Clear any break condition set with TIOCSBRK. */
       if ((cs->cs_creg[5] & ZSWR5_BREAK) != 0) {
               cs->cs_preg[5] &= ~ZSWR5_BREAK;
               cs->cs_creg[5] &= ~ZSWR5_BREAK;
               ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
       }

       /*
        * Drop all lines and cancel interrupts
        */
       zs_loadchannelregs(cs->cs_zc, zs_init_regs);
       splx(s);
}

/*
* Set ZS tty parameters from termios.
*
* This routine makes use of the fact that only registers
* 1, 3, 4, 5, 9, 10, 11, 12, 13, 14, and 15 are written.
*/
static int
zsparam(struct tty *tp, struct termios *t)
{
       int unit = ZS_UNIT(tp->t_dev);
       struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
       struct zs_chanstate *cs = sc->sc_cs[unit & 1];
       int cdiv = 0;   /* XXX gcc4 -Wuninitialized */
       int clkm = 0;   /* XXX gcc4 -Wuninitialized */
       int brgm = 0;   /* XXX gcc4 -Wuninitialized */
       int tcon = 0;   /* XXX gcc4 -Wuninitialized */
       int tmp, tmp5, cflag, s;

       tmp  = t->c_ospeed;
       tmp5 = t->c_ispeed;
       if (tmp < 0 || (tmp5 && tmp5 != tmp))
               return EINVAL;
       if (tmp == 0) {
               /* stty 0 => drop DTR and RTS */
               zs_modem(cs, 0, DMSET);
               return 0;
       }
       tmp = zsbaudrate(unit, tmp, &cdiv, &clkm, &brgm, &tcon);
       if (tmp < 0)
               return EINVAL;
       tp->t_ispeed = tp->t_ospeed = tmp;

       cflag = tp->t_cflag = t->c_cflag;
       if ((cflag & CSTOPB) != 0)
               cdiv |= ZSWR4_TWOSB;
       else
               cdiv |= ZSWR4_ONESB;
       if ((cflag & PARODD) == 0)
               cdiv |= ZSWR4_EVENP;
       if ((cflag & PARENB) != 0)
               cdiv |= ZSWR4_PARENB;

       switch (cflag & CSIZE) {
       case CS5:
               tmp  = ZSWR3_RX_5;
               tmp5 = ZSWR5_TX_5;
               break;
       case CS6:
               tmp  = ZSWR3_RX_6;
               tmp5 = ZSWR5_TX_6;
               break;
       case CS7:
               tmp  = ZSWR3_RX_7;
               tmp5 = ZSWR5_TX_7;
               break;
       case CS8:
       default:
               tmp  = ZSWR3_RX_8;
               tmp5 = ZSWR5_TX_8;
               break;
       }
       tmp  |= ZSWR3_RX_ENABLE;
       tmp5 |= ZSWR5_TX_ENABLE | ZSWR5_DTR | ZSWR5_RTS;

       /*
        * Block interrupts so that state will not
        * be altered until we are done setting it up.
        */
       s = splzs();
       cs->cs_preg[4]  = cdiv;
       cs->cs_preg[11] = clkm;
       cs->cs_preg[12] = tcon;
       cs->cs_preg[13] = tcon >> 8;
       cs->cs_preg[14] = brgm;
       cs->cs_preg[1]  = ZSWR1_RIE | ZSWR1_TIE | ZSWR1_SIE;
       cs->cs_preg[9]  = ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT;
       cs->cs_preg[10] = ZSWR10_NRZ;
       cs->cs_preg[15] = ZSWR15_BREAK_IE | ZSWR15_DCD_IE;

       /*
        * Output hardware flow control on the chip is horrendous: if
        * carrier detect drops, the receiver is disabled.  Hence we
        * can only do this when the carrier is on.
        */
       if ((cflag & CCTS_OFLOW) != 0 &&
           (cs->cs_zc->zc_csr & ZSRR0_DCD) != 0)
               tmp |= ZSWR3_HFC;
       cs->cs_preg[3] = tmp;
       cs->cs_preg[5] = tmp5;

       /*
        * If nothing is being transmitted, set up new current values,
        * else mark them as pending.
        */
       if (cs->cs_heldchange == 0) {
               if ((cs->cs_ttyp->t_state & TS_BUSY) != 0) {
                       cs->cs_heldtbc = cs->cs_tbc;
                       cs->cs_tbc = 0;
                       cs->cs_heldchange = 1;
               } else {
                       memcpy((void *)cs->cs_creg, (void *)cs->cs_preg, 16);
                       zs_loadchannelregs(cs->cs_zc, cs->cs_creg);
               }
       }
       splx(s);
       return 0;
}

/*
* search for the best matching baudrate
*/
static int
zsbaudrate(int unit, int wanted, int *divisor, int *clockmode, int *brgenmode,
   int *timeconst)
{
       int bestdiff, bestbps, source;

       bestdiff = bestbps = 0;
       unit = (unit & 1) << 2;
       for (source = 0; source < 4; ++source) {
               u_long freq = zs_frequencies[unit + source];
               int diff, bps, div, clkm, brgm, tcon;

               bps = div = clkm = brgm = tcon = 0;
               switch (source) {
               case 0: /* BRgen, PCLK */
                       brgm = ZSWR14_BAUD_ENA|ZSWR14_BAUD_FROM_PCLK;
                       break;
               case 1: /* BRgen, RTxC */
                       brgm = ZSWR14_BAUD_ENA;
                       break;
               case 2: /* RTxC */
                       clkm = ZSWR11_RXCLK_RTXC|ZSWR11_TXCLK_RTXC;
                       break;
               case 3: /* TRxC */
                       clkm = ZSWR11_RXCLK_TRXC|ZSWR11_TXCLK_TRXC;
                       break;
               }
               switch (source) {
               case 0:
               case 1:
                       div  = ZSWR4_CLK_X16;
                       clkm = ZSWR11_RXCLK_BAUD|ZSWR11_TXCLK_BAUD;
                       tcon = BPS_TO_TCONST(freq, wanted);
                       if (tcon < 0)
                               tcon = 0;
                       bps  = TCONST_TO_BPS(freq, tcon);
                       break;
               case 2:
               case 3:
                   {
                       int b1 = freq / 16, d1 = abs(b1 - wanted);
                       int b2 = freq / 32, d2 = abs(b2 - wanted);
                       int b3 = freq / 64, d3 = abs(b3 - wanted);

                       if (d1 < d2 && d1 < d3) {
                               div = ZSWR4_CLK_X16;
                               bps = b1;
                       } else if (d2 < d3 && d2 < d1) {
                               div = ZSWR4_CLK_X32;
                               bps = b2;
                       } else {
                               div = ZSWR4_CLK_X64;
                               bps = b3;
                       }
                       brgm = tcon = 0;
                       break;
                   }
               }
               diff = abs(bps - wanted);
               if (!source || diff < bestdiff) {
                       *divisor   = div;
                       *clockmode = clkm;
                       *brgenmode = brgm;
                       *timeconst = tcon;
                       bestbps    = bps;
                       bestdiff   = diff;
                       if (diff == 0)
                               break;
               }
       }
       /* Allow deviations upto 5% */
       if (20 * bestdiff > wanted)
               return -1;
       return bestbps;
}

/*
* Raise or lower modem control (DTR/RTS) signals.  If a character is
* in transmission, the change is deferred.
*/
static int
zs_modem(struct zs_chanstate *cs, int bits, int how)
{
       int s, mbits;

       bits  &= ZSWR5_DTR | ZSWR5_RTS;

       s = splzs();
       mbits  = cs->cs_preg[5] &  (ZSWR5_DTR | ZSWR5_RTS);

       switch (how) {
       case DMSET:
               mbits  = bits;
               break;
       case DMBIS:
               mbits |= bits;
               break;
       case DMBIC:
               mbits &= ~bits;
               break;
       case DMGET:
               splx(s);
               return mbits;
       }

       cs->cs_preg[5] = (cs->cs_preg[5] & ~(ZSWR5_DTR | ZSWR5_RTS)) | mbits;
       if (cs->cs_heldchange == 0) {
               if ((cs->cs_ttyp->t_state & TS_BUSY) != 0) {
                       cs->cs_heldtbc = cs->cs_tbc;
                       cs->cs_tbc = 0;
                       cs->cs_heldchange = 1;
               } else {
                       ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
               }
       }
       splx(s);
       return 0;
}

/*
* Write the given register set to the given zs channel in the proper order.
* The channel must not be transmitting at the time.  The receiver will
* be disabled for the time it takes to write all the registers.
*/
static void
zs_loadchannelregs(struct zschan *zc, uint8_t *reg)
{
       int i;

       zc->zc_csr = ZSM_RESET_ERR;     /* reset error condition */
       i = zc->zc_data;                /* drain fifo */
       i = zc->zc_data;
       i = zc->zc_data;
       ZS_WRITE(zc,  4, reg[4]);
       ZS_WRITE(zc, 10, reg[10]);
       ZS_WRITE(zc,  3, reg[3] & ~ZSWR3_RX_ENABLE);
       ZS_WRITE(zc,  5, reg[5] & ~ZSWR5_TX_ENABLE);
       ZS_WRITE(zc,  1, reg[1]);
       ZS_WRITE(zc,  9, reg[9]);
       ZS_WRITE(zc, 11, reg[11]);
       ZS_WRITE(zc, 12, reg[12]);
       ZS_WRITE(zc, 13, reg[13]);
       ZS_WRITE(zc, 14, reg[14]);
       ZS_WRITE(zc, 15, reg[15]);
       ZS_WRITE(zc,  3, reg[3]);
       ZS_WRITE(zc,  5, reg[5]);
       __USE(i);
}
#endif /* NZS > 1 */