/*      $NetBSD: zs_kgdb.c,v 1.15 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.
 *
 * 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 1.15 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/ofw/openfirm.h>
#include <dev/ic/z8530reg.h>
#include <machine/z8530var.h>

static void zs_setparam(struct zs_chanstate *, int, int);
static void zskgdb(struct zs_chanstate *);

struct zsops zsops_kgdb;

static u_char zs_kgdb_regs[16] = {
        0,      /* 0: CMD (reset, etc.) */
        0,      /* 1: ~(ZSWR1_RIE | ZSWR1_TIE | ZSWR1_SIE) */
        0,      /* 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,
        0,      /*10: Misc. TX/RX control bits */
        ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
        ((PCLK/32)/38400)-2,    /*12: BAUDLO (default=38400) */
        0,                      /*13: BAUDHI (default=38400) */
        ZSWR14_BAUD_ENA,
        ZSWR15_BREAK_IE,
};

/*
 * This replaces "zs_reset()" in the sparc driver.
 */
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);
}

#ifndef KGDB_DEVNAME
#define KGDB_DEVNAME "scca"
#endif
const char *zs_kgdb_devname = KGDB_DEVNAME;
/*
 * 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)
{
        extern const struct cdevsw zstty_cdevsw;
        struct zs_chanstate cs;
        volatile struct zschan *zc;
        int escc, escc_ch, obio, zs_offset;
        int channel = 0;
        u_int32_t reg[5];
        char name[16];

        if ((escc_ch = OF_finddevice(zs_kgdb_devname)) == -1)
                return;

        memset(name, 0, sizeof(name));
        if (OF_getprop(escc_ch, "device_type", name, sizeof(name)) == -1)
                return;

        if (strcmp(name, "serial") != 0)
                return;

        memset(name, 0, sizeof(name));
        if (OF_getprop(escc_ch, "name", name, sizeof(name)) == -1)
                return;

        if (strcmp(name, "ch-b") == 0)
                channel = 1;

        if (OF_getprop(escc_ch, "reg", reg, sizeof(reg)) < 4)
                return;
        zs_offset = reg[0];

        escc = OF_parent(escc_ch);
        obio = OF_parent(escc);

        if (OF_getprop(obio, "assigned-addresses", reg, sizeof(reg)) < 12)
                return;
        zc = (struct zschan *)(reg[2] + zs_offset);

        kgdb_dev = makedev(cdevsw_lookup_major(&zstty_cdevsw), channel);

        printf("zs_kgdb_init: attaching tty%02d at %d baud\n",
                channel, kgdb_rate);

        /* Setup temporary chanstate. */
        memset((void *)&cs, 0, sizeof(cs));
        cs.cs_channel = channel;
        cs.cs_brg_clk = PCLK / 16;
        cs.cs_reg_csr  = &zc->zc_csr;
        cs.cs_reg_data = &zc->zc_data;

        /* Now set parameters. (interrupts disabled) */
        zs_setparam(&cs, 0, kgdb_rate);

        /* Store the getc/putc functions and arg. */
        kgdb_attach(zs_getc, zs_putc, __UNVOLATILE(zc));
}

/*
 * This is a "hook" called by zstty_attach 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.
 */
static 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 *);

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");
}

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 */
};