root/sys/arch/sgimips/dev/zs_kgdb.c
/*      $NetBSD: zs_kgdb.c,v 1.17 2023/10/24 21:45:49 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 1.17 2023/10/24 21:45:49 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 *);

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

extern struct   zschan *zs_get_chan_addr (int, int);
extern int      zs_getc (void *);
extern void     zs_putc (void *, int);

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,
        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 | ZSWR11_TRXC_OUT_ENA,
        10,     /*12: BAUDLO (updated by KGDB_RATE) */
        0,      /*13: BAUDHI (updated by KGDB_RATE) */
        ZSWR14_BAUD_ENA,
        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)
{
        volatile struct zschan *zc;
        int channel, unit;
        extern const struct cdevsw zstty_cdevsw;

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

        unit = (kgdb_dev & 2) ? 1 : 0;  /* XXX ??? */
        channel = kgdb_dev & 1;
        printf("zs_kgdb_init: attaching to Serial(%d) at %d baud\n",
                   ((int)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, __UNVOLATILE(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");
}