/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2011 by Nathan Whitehorn. All rights reserved.
 *
 * 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 AUTHOR ``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 TOOLS GMBH 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>
#include <sys/endian.h>
#include <sys/param.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/priv.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/tty.h>
#include <machine/bus.h>

#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <dev/uart/uart.h>
#include <dev/uart/uart_cpu.h>
#include <dev/uart/uart_bus.h>

#include "phyp-hvcall.h"
#include "uart_if.h"

struct uart_phyp_softc {
        device_t dev;
        phandle_t node;
        int vtermid;

        struct tty *tp;
        struct resource *irqres;
        int irqrid;
        struct callout callout;
        void *sc_icookie;
        int polltime;

        struct mtx sc_mtx;
        int protocol;

        union {
                uint64_t u64[2];
                char str[16];
        } phyp_inbuf;
        uint64_t inbuflen;
        uint8_t outseqno;
};

static struct uart_phyp_softc   *console_sc = NULL;
#if defined(KDB)
static int                      alt_break_state;
#endif

enum {
        HVTERM1, HVTERMPROT
};

#define VS_DATA_PACKET_HEADER           0xff
#define VS_CONTROL_PACKET_HEADER        0xfe
#define  VSV_SET_MODEM_CTL              0x01
#define  VSV_MODEM_CTL_UPDATE           0x02
#define  VSV_RENEGOTIATE_CONNECTION     0x03
#define VS_QUERY_PACKET_HEADER          0xfd
#define  VSV_SEND_VERSION_NUMBER        0x01
#define  VSV_SEND_MODEM_CTL_STATUS      0x02
#define VS_QUERY_RESPONSE_PACKET_HEADER 0xfc

static int uart_phyp_probe(device_t dev);
static int uart_phyp_attach(device_t dev);
static void uart_phyp_intr(void *v);

static device_method_t uart_phyp_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         uart_phyp_probe),
        DEVMETHOD(device_attach,        uart_phyp_attach),

        DEVMETHOD_END
};

static driver_t uart_phyp_driver = {
        "uart",
        uart_phyp_methods,
        sizeof(struct uart_phyp_softc),
};

DRIVER_MODULE(uart_phyp, vdevice, uart_phyp_driver, 0, 0);

static cn_probe_t uart_phyp_cnprobe;
static cn_init_t uart_phyp_cninit;
static cn_term_t uart_phyp_cnterm;
static cn_getc_t uart_phyp_cngetc;
static cn_putc_t uart_phyp_cnputc;
static cn_grab_t uart_phyp_cngrab;
static cn_ungrab_t uart_phyp_cnungrab;

CONSOLE_DRIVER(uart_phyp);

static void uart_phyp_ttyoutwakeup(struct tty *tp);

static struct ttydevsw uart_phyp_tty_class = {
        .tsw_flags      = TF_INITLOCK|TF_CALLOUT,
        .tsw_outwakeup  = uart_phyp_ttyoutwakeup,
};

static int
uart_phyp_probe_node(struct uart_phyp_softc *sc)
{
        phandle_t node = sc->node;
        uint32_t reg;
        char buf[64];

        sc->inbuflen = 0;
        sc->outseqno = 0;

        if (OF_getprop(node, "name", buf, sizeof(buf)) <= 0)
                return (ENXIO);
        if (strcmp(buf, "vty") != 0)
                return (ENXIO);

        if (OF_getprop(node, "device_type", buf, sizeof(buf)) <= 0)
                return (ENXIO);
        if (strcmp(buf, "serial") != 0)
                return (ENXIO);

        reg = -1;
        OF_getencprop(node, "reg", &reg, sizeof(reg));
        if (reg == -1)
                return (ENXIO);
        sc->vtermid = reg;
        sc->node = node;

        if (OF_getprop(node, "compatible", buf, sizeof(buf)) <= 0)
                return (ENXIO);
        if (strcmp(buf, "hvterm1") == 0) {
                sc->protocol = HVTERM1;
                return (0);
        } else if (strcmp(buf, "hvterm-protocol") == 0) {
                sc->protocol = HVTERMPROT;
                return (0);
        }

        return (ENXIO);
}

static int
uart_phyp_probe(device_t dev)
{
        const char *name;
        struct uart_phyp_softc sc;
        int err;

        name = ofw_bus_get_name(dev);
        if (name == NULL || strcmp(name, "vty") != 0)
                return (ENXIO);

        sc.node = ofw_bus_get_node(dev);
        err = uart_phyp_probe_node(&sc);
        if (err != 0)
                return (err);

        device_set_desc(dev, "POWER Hypervisor Virtual Serial Port");

        return (err);
}

static void
uart_phyp_cnprobe(struct consdev *cp)
{
        char buf[64];
        ihandle_t stdout;
        phandle_t input, chosen;
        static struct uart_phyp_softc sc;

        if ((chosen = OF_finddevice("/chosen")) == -1)
                goto fail;

        /* Check if OF has an active stdin/stdout */
        input = -1;
        if (OF_getencprop(chosen, "stdout", &stdout,
            sizeof(stdout)) == sizeof(stdout) && stdout != 0)
                input = OF_instance_to_package(stdout);
        if (input == -1)
                goto fail;

        if (OF_getprop(input, "device_type", buf, sizeof(buf)) == -1)
                goto fail;
        if (strcmp(buf, "serial") != 0)
                goto fail;

        sc.node = input;
        if (uart_phyp_probe_node(&sc) != 0)
                goto fail;
        mtx_init(&sc.sc_mtx, "uart_phyp", NULL, MTX_SPIN | MTX_QUIET |
            MTX_NOWITNESS);

        cp->cn_pri = CN_NORMAL;
        console_sc = &sc;
        return;

fail:
        cp->cn_pri = CN_DEAD;
        return;
}

static int
uart_phyp_attach(device_t dev)
{
        struct uart_phyp_softc *sc;
        int unit;

        sc = device_get_softc(dev);
        sc->dev = dev;
        sc->node = ofw_bus_get_node(dev);
        uart_phyp_probe_node(sc);

        unit = device_get_unit(dev);
        sc->tp = tty_alloc(&uart_phyp_tty_class, sc);
        mtx_init(&sc->sc_mtx, device_get_nameunit(dev), NULL,
            MTX_SPIN | MTX_QUIET | MTX_NOWITNESS);

        if (console_sc != NULL && console_sc->vtermid == sc->vtermid) {
                sc->outseqno = console_sc->outseqno;
                console_sc = sc;
                sprintf(uart_phyp_consdev.cn_name, "ttyu%r", unit);
                tty_init_console(sc->tp, 0);
        }

        sc->irqrid = 0;
        sc->irqres = bus_alloc_resource_any(dev, SYS_RES_IRQ, &sc->irqrid,
            RF_ACTIVE | RF_SHAREABLE);
        if (sc->irqres != NULL) {
                bus_setup_intr(dev, sc->irqres, INTR_TYPE_TTY | INTR_MPSAFE,
                    NULL, uart_phyp_intr, sc, &sc->sc_icookie);
        } else {
                callout_init(&sc->callout, 1);
                sc->polltime = hz / 20;
                if (sc->polltime < 1)
                        sc->polltime = 1;
                callout_reset(&sc->callout, sc->polltime, uart_phyp_intr, sc);
        }

        tty_makedev(sc->tp, NULL, "u%r", unit);

        return (0);
}

static void
uart_phyp_cninit(struct consdev *cp)
{

        strcpy(cp->cn_name, "phypcons");
}

static void
uart_phyp_cnterm(struct consdev *cp)
{
}

static int
uart_phyp_get(struct uart_phyp_softc *sc, void *buffer, size_t bufsize)
{
        int err;
        int hdr = 0;
        uint64_t i, j;

        uart_lock(&sc->sc_mtx);
        if (sc->inbuflen == 0) {
                err = phyp_pft_hcall(H_GET_TERM_CHAR, sc->vtermid,
                    0, 0, 0, &sc->inbuflen, &sc->phyp_inbuf.u64[0],
                    &sc->phyp_inbuf.u64[1]);
#if BYTE_ORDER == LITTLE_ENDIAN
                sc->phyp_inbuf.u64[0] = be64toh(sc->phyp_inbuf.u64[0]);
                sc->phyp_inbuf.u64[1] = be64toh(sc->phyp_inbuf.u64[1]);
#endif
                if (err != H_SUCCESS) {
                        uart_unlock(&sc->sc_mtx);
                        return (-1);
                }
                hdr = 1;
        }

        if (sc->inbuflen == 0) {
                uart_unlock(&sc->sc_mtx);
                return (0);
        }

        if ((sc->protocol == HVTERMPROT) && (hdr == 1)) {
                sc->inbuflen = sc->inbuflen - 4;
                /* The VTERM protocol has a 4 byte header, skip it here. */
                memmove(&sc->phyp_inbuf.str[0], &sc->phyp_inbuf.str[4],
                    sc->inbuflen);
        }

        /*
         * Since version 2.11.0, QEMU became bug-compatible with
         * PowerVM's vty implementation, by inserting a \0 after
         * every \r going to the guest. Guests are expected to
         * workaround this issue by removing every \0 immediately
         * following a \r.
         */
        if (hdr == 1) {
                for (i = 0, j = 0; i < sc->inbuflen; i++, j++) {
                        if (i > j)
                                sc->phyp_inbuf.str[j] = sc->phyp_inbuf.str[i];

                        if (sc->phyp_inbuf.str[i] == '\r' &&
                            i < sc->inbuflen - 1 &&
                            sc->phyp_inbuf.str[i + 1] == '\0')
                                i++;
                }
                sc->inbuflen -= i - j;
        }

        if (bufsize > sc->inbuflen)
                bufsize = sc->inbuflen;

        memcpy(buffer, sc->phyp_inbuf.str, bufsize);
        sc->inbuflen -= bufsize;
        if (sc->inbuflen > 0)
                memmove(&sc->phyp_inbuf.str[0], &sc->phyp_inbuf.str[bufsize],
                    sc->inbuflen);

        uart_unlock(&sc->sc_mtx);
        return (bufsize);
}

static int
uart_phyp_put(struct uart_phyp_softc *sc, void *buffer, size_t bufsize)
{
        uint16_t seqno;
        uint64_t len = 0;
        int     err;

        union {
                uint64_t u64[2];
                char bytes[16];
        } cbuf;

        uart_lock(&sc->sc_mtx);
        switch (sc->protocol) {
        case HVTERM1:
                if (bufsize > 16)
                        bufsize = 16;
                memcpy(&cbuf, buffer, bufsize);
                len = bufsize;
                break;
        case HVTERMPROT:
                if (bufsize > 12)
                        bufsize = 12;
                seqno = sc->outseqno++;
                cbuf.bytes[0] = VS_DATA_PACKET_HEADER;
                cbuf.bytes[1] = 4 + bufsize; /* total length, max 16 bytes */
                cbuf.bytes[2] = (seqno >> 8) & 0xff;
                cbuf.bytes[3] = seqno & 0xff;
                memcpy(&cbuf.bytes[4], buffer, bufsize);
                len = 4 + bufsize;
                break;
        }

        do {
            err = phyp_hcall(H_PUT_TERM_CHAR, sc->vtermid, len, htobe64(cbuf.u64[0]),
                            htobe64(cbuf.u64[1]));
                DELAY(100);
        } while (err == H_BUSY);

        uart_unlock(&sc->sc_mtx);

        return (bufsize);
}

static int
uart_phyp_cngetc(struct consdev *cp)
{
        unsigned char c;
        int retval;

        retval = uart_phyp_get(console_sc, &c, 1);
        if (retval != 1)
                return (-1);
#if defined(KDB)
        kdb_alt_break(c, &alt_break_state);
#endif

        return (c);
}

static void
uart_phyp_cnputc(struct consdev *cp, int c)
{
        unsigned char ch = c;
        uart_phyp_put(console_sc, &ch, 1);
}

static void
uart_phyp_cngrab(struct consdev *cp)
{
}

static void
uart_phyp_cnungrab(struct consdev *cp)
{
}

static void
uart_phyp_ttyoutwakeup(struct tty *tp)
{
        struct uart_phyp_softc *sc;
        char buffer[8];
        int len;

        sc = tty_softc(tp);

        while ((len = ttydisc_getc(tp, buffer, sizeof(buffer))) != 0)
                uart_phyp_put(sc, buffer, len);
}

static void
uart_phyp_intr(void *v)
{
        struct uart_phyp_softc *sc = v;
        struct tty *tp = sc->tp;
        unsigned char c;
        int len;

        tty_lock(tp);
        while ((len = uart_phyp_get(sc, &c, 1)) > 0)
                ttydisc_rint(tp, c, 0);
        ttydisc_rint_done(tp);
        tty_unlock(tp);

        if (sc->irqres == NULL)
                callout_reset(&sc->callout, sc->polltime, uart_phyp_intr, sc);
}