/*      $NetBSD: zs_kgdb.c,v 1.11 2023/10/24 19:05:07 andvar Exp $      */

/*-
* Copyright (c) 1996 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Gordon W. Ross and Wayne Knowles.
*
* 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.
*/

/*
* Hooks for kgdb when attached via the z8530 driver
*
* To use this, build a kernel with: option KGDB, and
* boot that kernel with "-d".  (The kernel will call
* zs_kgdb_init, kgdb_connect.)  When the console prints
* "kgdb waiting..." you run "gdb -k kernel" and do:
*   (gdb) set remotebaud 19200
*   (gdb) target remote /dev/ttyb
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: zs_kgdb.c,v 1.11 2023/10/24 19:05:07 andvar Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/device.h>
#include <sys/conf.h>
#include <sys/ioctl.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/kgdb.h>

#include <dev/ic/z8530reg.h>
#include <machine/z8530var.h>

/*
* Hooks for kgdb when attached via the z8530 driver
*
* To use this, build a kernel with: option KGDB, and
* boot that kernel with "-d".  (The kernel will call
* zs_kgdb_init, kgdb_connect.)  When the console prints
* "kgdb waiting..." you run "gdb -k kernel" and do:
*   (gdb) set remotebaud 19200
*   (gdb) target remote /dev/ttyb
*/

void zs_kgdb_init(void);
void zskgdb(struct zs_chanstate *cs);

static void     zs_setparam(struct zs_chanstate *, int, int);
static struct   zsops zsops_kgdb;

extern struct   zschan *zs_get_chan_addr (int zs_unit, int channel);
extern int      zs_getc(void *arg);
extern void     zs_putc(void *arg, int c);

static u_char zs_kgdb_regs[16] = {
       0,      /* 0: CMD (reset, etc.) */
       0,      /* 1: No interrupts yet. */
       0,      /* 2: IVECT */
       ZSWR3_RX_8 | ZSWR3_RX_ENABLE,
       ZSWR4_CLK_X16 | ZSWR4_ONESB | ZSWR4_EVENP,
       ZSWR5_TX_8 | ZSWR5_TX_ENABLE,
       0,      /* 6: TXSYNC/SYNCLO */
       0,      /* 7: RXSYNC/SYNCHI */
       0,      /* 8: alias for data port */
       ZSWR9_MASTER_IE | ZSWR9_NO_VECTOR,
       0,      /*10: Misc. TX/RX control bits */
       ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
       14,     /*12: BAUDLO (default=9600) */
       0,      /*13: BAUDHI (default=9600) */
       ZSWR14_BAUD_ENA | ZSWR14_BAUD_FROM_PCLK,
       ZSWR15_BREAK_IE,
};

static void
zs_setparam(struct zs_chanstate *cs, int iena, int rate)
{
       int s, tconst;

       memcpy(cs->cs_preg, zs_kgdb_regs, 16);

       if (iena) {
               cs->cs_preg[1] = ZSWR1_RIE | ZSWR1_SIE;
       }

       /* Initialize the speed, etc. */
       tconst = BPS_TO_TCONST(cs->cs_brg_clk, rate);

       cs->cs_preg[5] |= ZSWR5_DTR | ZSWR5_RTS;
       cs->cs_preg[12] = tconst;
       cs->cs_preg[13] = tconst >> 8;

       s = splhigh();
       zs_loadchannelregs(cs);
       splx(s);
}

/*
* Set up for kgdb; called at boot time before configuration.
* KGDB interrupts will be enabled later when zs0 is configured.
* Called after cninit(), so printf() etc. works.
*/
void
zs_kgdb_init(void)
{
       struct zschan *zc;
       int channel, unit;
       extern const struct cdevsw zstty_cdevsw;

       if (cdevsw_lookup(kgdb_dev) != &zstty_cdevsw)
               return;

       unit = (kgdb_dev & 2) ? 2 : 0;
       channel = kgdb_dev & 1;
       printf("zs_kgdb_init: attaching Serial(%lld) at %d baud\n",
                  (kgdb_dev & 3), kgdb_rate);

       zc = zs_get_chan_addr(unit, channel);

       /* Attach KGDB comms functions to this device */
       kgdb_attach(zs_getc, zs_putc, (void *)zc);
}

/*
* This is a "hook" called by the MI zstty_attach driver
* to allow the tty to be "taken over" for exclusive use by kgdb.
* Return non-zero if this is the kgdb port.
*
* Set the speed to kgdb_rate, CS8, etc.
*/
int
zs_check_kgdb(struct zs_chanstate *cs, int dev)
{

       if (dev != kgdb_dev)
               return (0);

       /*
        * Yes, this is port in use by kgdb.
        */
       cs->cs_private = NULL;
       cs->cs_ops = &zsops_kgdb;

       /* Now set parameters. (interrupts enabled) */
       zs_setparam(cs, 1, kgdb_rate);

       return (1);
}

/*
* KGDB framing character received: enter kernel debugger.  This probably
* should time out after a few seconds to avoid hanging on spurious input.
*/
void
zskgdb(struct zs_chanstate *cs)
{
       int unit = minor(kgdb_dev);

       printf("zstty%d: kgdb interrupt\n", unit);
       /* This will trap into the debugger. */
       kgdb_connect(1);
}


/****************************************************************
* Interface to the lower layer (zscc)
****************************************************************/

static void zs_kgdb_rxint(struct zs_chanstate *);
static void zs_kgdb_stint(struct zs_chanstate *, int);
static void zs_kgdb_txint(struct zs_chanstate *);
static void zs_kgdb_softint(struct zs_chanstate *);

static struct zsops zsops_kgdb = {
       zs_kgdb_rxint,          /* receive char available */
       zs_kgdb_stint,          /* external/status */
       zs_kgdb_txint,          /* xmit buffer empty */
       zs_kgdb_softint,        /* process software interrupt */
};

int kgdb_input_lost;

static void
zs_kgdb_rxint(struct zs_chanstate *cs)
{
       register u_char c, rr1;

       /*
        * First read the status, because reading the received char
        * destroys the status of this char.
        */
       rr1 = zs_read_reg(cs, 1);
       c = zs_read_data(cs);

       if (rr1 & (ZSRR1_FE | ZSRR1_DO | ZSRR1_PE)) {
               /* Clear the receive error. */
               zs_write_csr(cs, ZSWR0_RESET_ERRORS);
       }

       if (c == KGDB_START) {
               zskgdb(cs);
       } else {
               kgdb_input_lost++;
       }
}

static void
zs_kgdb_txint(register struct zs_chanstate *cs)
{
       zs_write_csr(cs, ZSWR0_RESET_TXINT);
}

static void
zs_kgdb_stint(register struct zs_chanstate *cs, int force)
{
       register int rr0;

       rr0 = zs_read_csr(cs);
       zs_write_csr(cs, ZSWR0_RESET_STATUS);

       /*
        * Check here for console break, so that we can abort
        * even when interrupts are locking up the machine.
        */
       if (rr0 & ZSRR0_BREAK) {
               zskgdb(cs);
       }
}

static void
zs_kgdb_softint(struct zs_chanstate *cs)
{
       printf("zs_kgdb_softint?\n");
}

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