/*      $OpenBSD: sfuart.c,v 1.6 2022/07/12 17:14:12 jca Exp $  */
/*
 * Copyright (c) 2019 Mark Kettenis <kettenis@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/tty.h>

#include <machine/bus.h>
#include <machine/fdt.h>

#include <dev/cons.h>

#include <dev/ofw/fdt.h>
#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_clock.h>

#define UART_TXDATA                     0x0000
#define  UART_TXDATA_FULL               (1U << 31)
#define UART_RXDATA                     0x0004
#define  UART_RXDATA_EMPTY              (1U << 31)
#define UART_TXCTRL                     0x0008
#define  UART_TXCTRL_TXEN               (1 << 0)
#define  UART_TXCTRL_NSTOP              (1 << 1)
#define  UART_TXCTRL_TXCNT_SHIFT        16
#define  UART_TXCTRL_TXCNT_MASK         (7 << 16)
#define UART_RXCTRL                     0x000c
#define  UART_RXCTRL_RXEN               (1 << 0)
#define  UART_RXCTRL_RXCNT_SHIFT        16
#define  UART_RXCTRL_RXCNT_MASK         (7 << 16)
#define UART_IE                         0x0010
#define  UART_IE_TXWM                   (1 << 0)
#define  UART_IE_RXWM                   (1 << 1)
#define UART_IP                         0x0014
#define  UART_IP_TXWM                   (1 << 0)
#define  UART_IP_RXWM                   (1 << 1)
#define UART_DIV                        0x0018

#define UART_SPACE                      28
#define UART_FIFO_SIZE                  8

#define HREAD4(sc, reg)                                                 \
        (bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
#define HWRITE4(sc, reg, val)                                           \
        bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
#define HSET4(sc, reg, bits)                                            \
        HWRITE4((sc), (reg), HREAD4((sc), (reg)) | (bits))
#define HCLR4(sc, reg, bits)                                            \
        HWRITE4((sc), (reg), HREAD4((sc), (reg)) & ~(bits))

cdev_decl(com);
cdev_decl(sfuart);

#define DEVUNIT(x)      (minor(x) & 0x7f)
#define DEVCUA(x)       (minor(x) & 0x80)

struct cdevsw sfuartdev = cdev_tty_init(2, sfuart);

struct sfuart_softc {
        struct device           sc_dev;
        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;

        uint32_t                sc_frequency;

        struct soft_intrhand    *sc_si;
        void                    *sc_ih;

        struct tty              *sc_tty;
        int                     sc_conspeed;
        int                     sc_floods;
        int                     sc_overflows;
        int                     sc_halt;
        int                     sc_cua;
        int                     *sc_ibuf, *sc_ibufp, *sc_ibufhigh, *sc_ibufend;
#define SFUART_IBUFSIZE         128
#define SFUART_IHIGHWATER       100
        int                     sc_ibufs[2][SFUART_IBUFSIZE];
};

int     sfuart_match(struct device *, void *, void *);
void    sfuart_attach(struct device *, struct device *, void *);

struct cfdriver sfuart_cd = {
        NULL, "sfuart", DV_TTY
};

const struct cfattach sfuart_ca = {
        sizeof(struct sfuart_softc), sfuart_match, sfuart_attach
};

bus_space_tag_t sfuartconsiot;
bus_space_handle_t sfuartconsioh;

struct sfuart_softc *sfuart_sc(dev_t);

int     sfuart_intr(void *);
void    sfuart_softintr(void *);
void    sfuart_start(struct tty *);

int     sfuartcnattach(bus_space_tag_t, bus_addr_t);
int     sfuartcngetc(dev_t);
void    sfuartcnputc(dev_t, int);
void    sfuartcnpollc(dev_t, int);

void
sfuart_init_cons(void)
{
        struct fdt_reg reg;
        void *node;

        if ((node = fdt_find_cons("sifive,uart0")) == NULL)
                return;
        if (fdt_get_reg(node, 0, &reg))
                return;

        sfuartcnattach(fdt_cons_bs_tag, reg.addr);
}

int
sfuart_match(struct device *parent, void *match, void *aux)
{
        struct fdt_attach_args *faa = aux;

        return OF_is_compatible(faa->fa_node, "sifive,uart0");
}

void
sfuart_attach(struct device *parent, struct device *self, void *aux)
{
        struct sfuart_softc *sc = (struct sfuart_softc *)self;
        struct fdt_attach_args *faa = aux;
        int maj;

        if (faa->fa_nreg < 1) {
                printf(": no registers\n");
                return;
        }

        sc->sc_iot = faa->fa_iot;
        if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
            faa->fa_reg[0].size, 0, &sc->sc_ioh)) {
                printf(": can't map registers\n");
                return;
        }

        sc->sc_frequency = clock_get_frequency(faa->fa_node, NULL);
        if (faa->fa_node == stdout_node) {
                /* Locate the major number. */
                for (maj = 0; maj < nchrdev; maj++)
                        if (cdevsw[maj].d_open == sfuartopen)
                                break;
                cn_tab->cn_dev = makedev(maj, sc->sc_dev.dv_unit);
                sc->sc_conspeed = stdout_speed;
                printf(": console");
        }

        sc->sc_si = softintr_establish(IPL_TTY, sfuart_softintr, sc);
        if (sc->sc_si == NULL) {
                printf(": can't establish soft interrupt\n");
                return;
        }

        sc->sc_ih = fdt_intr_establish_idx(faa->fa_node, 0, IPL_TTY,
            sfuart_intr, sc, sc->sc_dev.dv_xname);
        if (sc->sc_ih == NULL) {
                printf(": can't establish hard interrupt\n");
                return;
        }

        printf("\n");
}

int
sfuart_intr(void *arg)
{
        struct sfuart_softc *sc = arg;
        struct tty *tp = sc->sc_tty;
        int *p;
        uint32_t val;
        int c, handled = 0;

        if (tp == NULL)
                return 0;

        if (!ISSET(HREAD4(sc, UART_TXDATA), UART_TXDATA_FULL) &&
            ISSET(tp->t_state, TS_BUSY)) {
                CLR(tp->t_state, TS_BUSY | TS_FLUSH);
                if (sc->sc_halt > 0)
                        wakeup(&tp->t_outq);
                (*linesw[tp->t_line].l_start)(tp);
                handled = 1;
        }

        p = sc->sc_ibufp;
        val = HREAD4(sc, UART_RXDATA);
        while (!ISSET(val, UART_RXDATA_EMPTY)) {
                c = val & 0xff;

                if (p >= sc->sc_ibufend)
                        sc->sc_floods++;
                else
                        *p++ = c;

                val = HREAD4(sc, UART_RXDATA);
                handled = 1;
        }
        if (sc->sc_ibufp != p) {
                sc->sc_ibufp = p;
                softintr_schedule(sc->sc_si);
        }

        return handled;
}

void
sfuart_softintr(void *arg)
{
        struct sfuart_softc *sc = arg;
        struct tty *tp = sc->sc_tty;
        int *ibufp, *ibufend;
        int s;

        if (sc->sc_ibufp == sc->sc_ibuf)
                return;

        s = spltty();

        ibufp = sc->sc_ibuf;
        ibufend = sc->sc_ibufp;

        if (ibufp == ibufend) {
                splx(s);
                return;
        }

        sc->sc_ibufp = sc->sc_ibuf = (ibufp == sc->sc_ibufs[0]) ?
            sc->sc_ibufs[1] : sc->sc_ibufs[0];
        sc->sc_ibufhigh = sc->sc_ibuf + SFUART_IHIGHWATER;
        sc->sc_ibufend = sc->sc_ibuf + SFUART_IBUFSIZE;

        if (tp == NULL || !ISSET(tp->t_state, TS_ISOPEN)) {
                splx(s);
                return;
        }

        splx(s);

        while (ibufp < ibufend) {
                int i = *ibufp++;
#ifdef DDB
                if (tp->t_dev == cn_tab->cn_dev) {
                        int j = db_rint(i);

                        if (j == 1)     /* Escape received, skip */
                                continue;
                        if (j == 2)     /* Second char wasn't 'D' */
                                (*linesw[tp->t_line].l_rint)(27, tp);
                }
#endif
                (*linesw[tp->t_line].l_rint)(i, tp);
        }
}

int
sfuart_param(struct tty *tp, struct termios *t)
{
        struct sfuart_softc *sc = sfuart_sc(tp->t_dev);
        int ospeed = t->c_ospeed;
        uint32_t div;

        /* Check requested parameters. */
        if (ospeed < 0 || (t->c_ispeed && t->c_ispeed != t->c_ospeed))
                return EINVAL;

        switch (ISSET(t->c_cflag, CSIZE)) {
        case CS5:
        case CS6:
        case CS7:
                return EINVAL;
        case CS8:
                break;
        }

        if (ospeed != 0) {
                while (ISSET(tp->t_state, TS_BUSY)) {
                        int error;

                        sc->sc_halt++;
                        error = ttysleep(tp, &tp->t_outq,
                            TTOPRI | PCATCH, "sfuprm");
                        sc->sc_halt--;
                        if (error) {
                                sfuart_start(tp);
                                return error;
                        }
                }

                div = (sc->sc_frequency + ospeed / 2) / ospeed;
                if (div < 16 || div > 65536)
                        return EINVAL;
                HWRITE4(sc, UART_DIV, div - 1);
        }

        tp->t_ispeed = t->c_ispeed;
        tp->t_ospeed = t->c_ospeed;
        tp->t_cflag = t->c_cflag;

        /* Just to be sure... */
        sfuart_start(tp);
        return 0;
}

void
sfuart_start(struct tty *tp)
{
        struct sfuart_softc *sc = sfuart_sc(tp->t_dev);
        int stat;
        int s;

        s = spltty();
        if (ISSET(tp->t_state, TS_BUSY))
                goto out;
        if (ISSET(tp->t_state, TS_TIMEOUT | TS_TTSTOP) || sc->sc_halt > 0)
                goto out;
        ttwakeupwr(tp);
        if (tp->t_outq.c_cc == 0) {
                HCLR4(sc, UART_IE, UART_IE_TXWM);
                goto out;
        }
        SET(tp->t_state, TS_BUSY);

        stat = HREAD4(sc, UART_TXDATA);
        while ((stat & UART_TXDATA_FULL) == 0 && tp->t_outq.c_cc != 0) {
                HWRITE4(sc, UART_TXDATA, getc(&tp->t_outq));
                stat = HREAD4(sc, UART_TXDATA);
        }
        HSET4(sc, UART_IE, UART_IE_TXWM);
out:
        splx(s);
}

int
sfuartopen(dev_t dev, int flag, int mode, struct proc *p)
{
        struct sfuart_softc *sc = sfuart_sc(dev);
        struct tty *tp;
        int error;
        int s;

        if (sc == NULL)
                return ENXIO;

        s = spltty();
        if (sc->sc_tty == NULL)
                tp = sc->sc_tty = ttymalloc(0);
        else
                tp = sc->sc_tty;
        splx(s);

        tp->t_oproc = sfuart_start;
        tp->t_param = sfuart_param;
        tp->t_dev = dev;

        if (!ISSET(tp->t_state, TS_ISOPEN)) {
                SET(tp->t_state, TS_WOPEN);
                ttychars(tp);
                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 =
                    sc->sc_conspeed ? sc->sc_conspeed : B115200;

                s = spltty();

                sfuart_param(tp, &tp->t_termios);
                ttsetwater(tp);

                sc->sc_ibufp = sc->sc_ibuf = sc->sc_ibufs[0];
                sc->sc_ibufhigh = sc->sc_ibuf + SFUART_IHIGHWATER;
                sc->sc_ibufend = sc->sc_ibuf + SFUART_IBUFSIZE;

                /* Enable transmit. */
                HWRITE4(sc, UART_TXCTRL, UART_TXCTRL_TXEN |
                    ((UART_FIFO_SIZE / 2) << UART_TXCTRL_TXCNT_SHIFT));

                /* Enable receive. */
                HWRITE4(sc, UART_RXCTRL, UART_RXCTRL_RXEN |
                    (0 << UART_RXCTRL_RXCNT_SHIFT));

                /* Enable interrupts. */
                HSET4(sc, UART_IE, UART_IE_RXWM);

                /* No carrier detect support. */
                SET(tp->t_state, TS_CARR_ON);
        } else if (ISSET(tp->t_state, TS_XCLUDE) && suser(p) != 0)
                return EBUSY;
        else
                s = spltty();

        if (DEVCUA(dev)) {
                if (ISSET(tp->t_state, TS_ISOPEN)) {
                        /* Ah, but someone already is dialed in... */
                        splx(s);
                        return EBUSY;
                }
                sc->sc_cua = 1;         /* We go into CUA mode. */
        } else {
                if (ISSET(flag, O_NONBLOCK) && sc->sc_cua) {
                        /* Opening TTY non-blocking... but the CUA is busy. */
                        splx(s);
                        return EBUSY;
                } else {
                        while (sc->sc_cua) {
                                SET(tp->t_state, TS_WOPEN);
                                error = ttysleep(tp, &tp->t_rawq,
                                    TTIPRI | PCATCH, ttopen);
                                /*
                                 * If TS_WOPEN has been reset, that means the
                                 * cua device has been closed.
                                 * We don't want to fail in that case,
                                 * so just go around again.
                                 */
                                if (error && ISSET(tp->t_state, TS_WOPEN)) {
                                        CLR(tp->t_state, TS_WOPEN);
                                        splx(s);
                                        return error;
                                }
                        }
                }
        }
        splx(s);

        return (*linesw[tp->t_line].l_open)(dev, tp, p);
}

int
sfuartclose(dev_t dev, int flag, int mode, struct proc *p)
{
        struct sfuart_softc *sc = sfuart_sc(dev);
        struct tty *tp = sc->sc_tty;
        int s;

        if (!ISSET(tp->t_state, TS_ISOPEN))
                return 0;

        (*linesw[tp->t_line].l_close)(tp, flag, p);
        s = spltty();
        if (!ISSET(tp->t_state, TS_WOPEN)) {
                /* Disable interrupts */
                HCLR4(sc, UART_IE, UART_IE_TXWM | UART_IE_RXWM);
        }
        CLR(tp->t_state, TS_BUSY | TS_FLUSH);
        sc->sc_cua = 0;
        splx(s);
        ttyclose(tp);

        return 0;
}

int
sfuartread(dev_t dev, struct uio *uio, int flag)
{
        struct tty *tp = sfuarttty(dev);

        if (tp == NULL)
                return ENODEV;

        return (*linesw[tp->t_line].l_read)(tp, uio, flag);
}

int
sfuartwrite(dev_t dev, struct uio *uio, int flag)
{
        struct tty *tp = sfuarttty(dev);

        if (tp == NULL)
                return ENODEV;

        return (*linesw[tp->t_line].l_write)(tp, uio, flag);
}

int
sfuartioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p)
{
        struct sfuart_softc *sc = sfuart_sc(dev);
        struct tty *tp;
        int error;

        if (sc == NULL)
                return ENODEV;

        tp = sc->sc_tty;
        if (tp == NULL)
                return ENXIO;

        error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p);
        if (error >= 0)
                return error;

        error = ttioctl(tp, cmd, data, flag, p);
        if (error >= 0)
                return error;

        switch(cmd) {
        case TIOCSBRK:
        case TIOCCBRK:
        case TIOCSDTR:
        case TIOCCDTR:
        case TIOCMSET:
        case TIOCMBIS:
        case TIOCMBIC:
        case TIOCMGET:
        case TIOCGFLAGS:
                break;
        case TIOCSFLAGS:
                error = suser(p);
                if (error != 0)
                        return EPERM;
                break;
        default:
                return ENOTTY;
        }

        return 0;
}

int
sfuartstop(struct tty *tp, int flag)
{
        return 0;
}

struct tty *
sfuarttty(dev_t dev)
{
        struct sfuart_softc *sc = sfuart_sc(dev);

        if (sc == NULL)
                return NULL;
        return sc->sc_tty;
}

struct sfuart_softc *
sfuart_sc(dev_t dev)
{
        int unit = DEVUNIT(dev);

        if (unit >= sfuart_cd.cd_ndevs)
                return NULL;
        return (struct sfuart_softc *)sfuart_cd.cd_devs[unit];
}

int
sfuartcnattach(bus_space_tag_t iot, bus_addr_t iobase)
{
        static struct consdev sfuartcons = {
                NULL, NULL, sfuartcngetc, sfuartcnputc, sfuartcnpollc, NULL,
                NODEV, CN_MIDPRI
        };
        int maj;

        sfuartconsiot = iot;
        if (bus_space_map(iot, iobase, UART_SPACE, 0, &sfuartconsioh))
                return ENOMEM;

        /* Look for major of com(4) to replace. */
        for (maj = 0; maj < nchrdev; maj++)
                if (cdevsw[maj].d_open == comopen)
                        break;
        if (maj == nchrdev)
                return ENXIO;

        cn_tab = &sfuartcons;
        cn_tab->cn_dev = makedev(maj, 0);
        cdevsw[maj] = sfuartdev;        /* KLUDGE */

        return 0;
}

int
sfuartcngetc(dev_t dev)
{
        uint32_t val;

        do {
                val = bus_space_read_4(sfuartconsiot, sfuartconsioh, UART_RXDATA);
                if (val & UART_RXDATA_EMPTY)
                        CPU_BUSY_CYCLE();
        } while ((val & UART_RXDATA_EMPTY));

        return (val & 0xff);
}

void
sfuartcnputc(dev_t dev, int c)
{
        while (bus_space_read_4(sfuartconsiot, sfuartconsioh, UART_TXDATA) &
            UART_TXDATA_FULL)
                CPU_BUSY_CYCLE();
        bus_space_write_4(sfuartconsiot, sfuartconsioh, UART_TXDATA, c);
}

void
sfuartcnpollc(dev_t dev, int on)
{
}