/*      $OpenBSD: iicmux.c,v 1.2 2022/04/06 18:59:28 naddy Exp $        */
/*
 * Copyright (c) 2021 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/systm.h>
#include <sys/malloc.h>
#include <sys/device.h>

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

#define _I2C_PRIVATE
#include <dev/i2c/i2cvar.h>

#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_misc.h>
#include <dev/ofw/ofw_pinctrl.h>

#define IICMUX_MAX_CHANNELS     4

struct iicmux_bus {
        struct iicmux_softc     *pb_sc;
        int                     pb_node;
        int                     pb_channel;
        struct i2c_controller   pb_ic;
        struct i2c_bus          pb_ib;
        struct device           *pb_iic;
};

struct iicmux_softc {
        struct device           sc_dev;
        i2c_tag_t               sc_tag;

        int                     sc_node;
        int                     sc_channel;
        int                     sc_nchannel;
        struct iicmux_bus       sc_bus[IICMUX_MAX_CHANNELS];
        const char              *sc_busnames[IICMUX_MAX_CHANNELS];
        struct rwlock           sc_lock;

        int                     sc_enable;
};

int     iicmux_match(struct device *, void *, void *);
void    iicmux_attach(struct device *, struct device *, void *);

const struct cfattach iicmux_ca = {
        sizeof(struct iicmux_softc), iicmux_match, iicmux_attach
};

struct cfdriver iicmux_cd = {
        NULL, "iicmux", DV_DULL
};

int     iicmux_acquire_bus(void *, int);
void    iicmux_release_bus(void *, int);
int     iicmux_exec(void *, i2c_op_t, i2c_addr_t, const void *, size_t,
            void *, size_t, int);
void    iicmux_bus_scan(struct device *, struct i2cbus_attach_args *, void *);

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

        return OF_is_compatible(faa->fa_node, "i2c-mux-pinctrl");
}

void
iicmux_attach(struct device *parent, struct device *self, void *aux)
{
        struct iicmux_softc *sc = (struct iicmux_softc *)self;
        struct fdt_attach_args *faa = aux;
        int node = faa->fa_node;
        uint32_t phandle;
        char *names;
        char *name;
        char *end;
        int len;

        sc->sc_channel = -1;    /* unknown */
        rw_init(&sc->sc_lock, sc->sc_dev.dv_xname);

        phandle = OF_getpropint(node, "i2c-parent", 0);
        sc->sc_tag = i2c_byphandle(phandle);
        if (sc->sc_tag == NULL) {
                printf(": can't find parent bus\n");
                return;
        }

        len = OF_getproplen(node, "pinctrl-names");
        if (len <= 0) {
                printf(": no channels\n");
                return;
        }

        names = malloc(len, M_DEVBUF, M_WAITOK);
        OF_getprop(node, "pinctrl-names", names, len);
        end = names + len;
        name = names;
        while (name < end) {
                if (strcmp(name, "idle") == 0)
                        break;

                if (sc->sc_nchannel >= IICMUX_MAX_CHANNELS) {
                        printf(": too many channels\n");
                        free(names, M_DEVBUF, len);
                        return;
                }

                sc->sc_busnames[sc->sc_nchannel] = name;
                name += strlen(name) + 1;
                sc->sc_nchannel++;
        }

        printf("\n");

        sc->sc_node = node;
        for (node = OF_child(node); node; node = OF_peer(node)) {
                struct i2cbus_attach_args iba;
                struct iicmux_bus *pb;
                uint32_t channel;

                channel = OF_getpropint(node, "reg", -1);
                if (channel >= sc->sc_nchannel)
                        continue;

                pb = &sc->sc_bus[channel];
                pb->pb_sc = sc;
                pb->pb_node = node;
                pb->pb_channel = channel;
                pb->pb_ic.ic_cookie = pb;
                pb->pb_ic.ic_acquire_bus = iicmux_acquire_bus;
                pb->pb_ic.ic_release_bus = iicmux_release_bus;
                pb->pb_ic.ic_exec = iicmux_exec;

                /* Configure the child busses. */
                memset(&iba, 0, sizeof(iba));
                iba.iba_name = "iic";
                iba.iba_tag = &pb->pb_ic;
                iba.iba_bus_scan = iicmux_bus_scan;
                iba.iba_bus_scan_arg = &pb->pb_node;

                config_found(&sc->sc_dev, &iba, iicbus_print);

                pb->pb_ib.ib_node = node;
                pb->pb_ib.ib_ic = &pb->pb_ic;
                i2c_register(&pb->pb_ib);
        }
}

int
iicmux_set_channel(struct iicmux_softc *sc, int channel, int flags)
{
        int error;

        if (channel < -1 || channel >= sc->sc_nchannel)
                return ENXIO;

        if (sc->sc_channel == channel)
                return 0;

        error = pinctrl_byname(sc->sc_node, sc->sc_busnames[channel]);
        if (error == 0)
                sc->sc_channel = channel;

        return error ? EIO : 0;
}

int
iicmux_acquire_bus(void *cookie, int flags)
{
        struct iicmux_bus *pb = cookie;
        struct iicmux_softc *sc = pb->pb_sc;
        int rwflags = RW_WRITE;
        int error;

        if (flags & I2C_F_POLL)
                rwflags |= RW_NOSLEEP;

        error = rw_enter(&sc->sc_lock, rwflags);
        if (error)
                return error;

        /* Acquire parent bus. */
        error = iic_acquire_bus(sc->sc_tag, flags);
        if (error) {
                rw_exit_write(&sc->sc_lock);
                return error;
        }

        error = iicmux_set_channel(sc, pb->pb_channel, flags);
        if (error) {
                iic_release_bus(sc->sc_tag, flags);
                rw_exit_write(&sc->sc_lock);
                return error;
        }

        return 0;
}

void
iicmux_release_bus(void *cookie, int flags)
{
        struct iicmux_bus *pb = cookie;
        struct iicmux_softc *sc = pb->pb_sc;

        if (pinctrl_byname(sc->sc_node, "idle") == 0)
                sc->sc_channel = -1;

        /* Release parent bus. */
        iic_release_bus(sc->sc_tag, flags);
        rw_exit_write(&sc->sc_lock);
}

int
iicmux_exec(void *cookie, i2c_op_t op, i2c_addr_t addr, const void *cmd,
    size_t cmdlen, void *buf, size_t buflen, int flags)
{
        struct iicmux_bus *pb = cookie;
        struct iicmux_softc *sc = pb->pb_sc;

        rw_assert_wrlock(&sc->sc_lock);

        /* Issue the transaction on the parent bus. */
        return iic_exec(sc->sc_tag, op, addr, cmd, cmdlen, buf, buflen, flags);
}

void
iicmux_bus_scan(struct device *self, struct i2cbus_attach_args *iba, void *arg)
{
        int iba_node = *(int *)arg;
        struct i2c_attach_args ia;
        char name[32];
        uint32_t reg[1];
        int node;

        for (node = OF_child(iba_node); node; node = OF_peer(node)) {
                memset(name, 0, sizeof(name));
                memset(reg, 0, sizeof(reg));

                if (OF_getprop(node, "compatible", name, sizeof(name)) == -1)
                        continue;
                if (name[0] == '\0')
                        continue;

                if (OF_getprop(node, "reg", &reg, sizeof(reg)) != sizeof(reg))
                        continue;

                memset(&ia, 0, sizeof(ia));
                ia.ia_tag = iba->iba_tag;
                ia.ia_addr = bemtoh32(&reg[0]);
                ia.ia_name = name;
                ia.ia_cookie = &node;
                config_found(self, &ia, iic_print);
        }
}