/*      $OpenBSD: bcm2835_bsc.c,v 1.5 2026/01/05 20:06:15 patrick Exp $ */
/*
 * Copyright (c) 2020 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/device.h>

#include <machine/intr.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_clock.h>
#include <dev/ofw/ofw_misc.h>
#include <dev/ofw/ofw_pinctrl.h>
#include <dev/ofw/fdt.h>

/* Registers. */
#define BSC_C           0x00
#define  BSC_C_I2CEN    (1 << 15)
#define  BSC_C_INTR     (1 << 10)
#define  BSC_C_INTT     (1 << 9)
#define  BSC_C_INTD     (1 << 8)
#define  BSC_C_ST       (1 << 7)
#define  BSC_C_CLEAR    (0x3 << 4)
#define  BSC_C_READ     (1 << 0)
#define BSC_S           0x04
#define  BSC_S_CLKT     (1 << 9)
#define  BSC_S_ERR      (1 << 8)
#define  BSC_S_RXF      (1 << 7)
#define  BSC_S_TXE      (1 << 6)
#define  BSC_S_RXD      (1 << 5)
#define  BSC_S_TXD      (1 << 4)
#define  BSC_S_RXR      (1 << 3)
#define  BSC_S_TXW      (1 << 2)
#define  BSC_S_DONE     (1 << 1)
#define  BSC_S_TA       (1 << 0)
#define BSC_DLEN        0x08
#define BSC_A           0x0c
#define BSC_FIFO        0x10
#define BSC_DIV         0x14
#define BSC_DEL         0x18
#define  BSC_DEL_FEDL_SHIFT     16
#define  BSC_DEL_REDL_SHIFT     0
#define BSC_CLKT        0x1c

#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))

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

        int                     sc_node;
        struct i2c_controller   sc_ic;
        struct i2c_bus          sc_ib;
};

int     bcmbsc_match(struct device *, void *, void *);
void    bcmbsc_attach(struct device *, struct device *, void *);

const struct cfattach bcmbsc_ca = {
        sizeof (struct bcmbsc_softc), bcmbsc_match, bcmbsc_attach
};

struct cfdriver bcmbsc_cd = {
        NULL, "bcmbsc", DV_DULL
};

int     bcmbsc_acquire_bus(void *, int);
void    bcmbsc_release_bus(void *, int);
int     bcmbsc_exec(void *, i2c_op_t, i2c_addr_t, const void *, size_t,
            void *, size_t, int);

void    bcmbsc_bus_scan(struct device *, struct i2cbus_attach_args *, void *);

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

        return OF_is_compatible(faa->fa_node, "brcm,bcm2835-i2c");
}

void
bcmbsc_attach(struct device *parent, struct device *self, void *aux)
{
        struct bcmbsc_softc *sc = (struct bcmbsc_softc *)self;
        struct fdt_attach_args *faa = aux;
        struct i2cbus_attach_args iba;
        uint32_t clock_speed, bus_speed;
        uint32_t div, fedl, redl;

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

        sc->sc_iot = faa->fa_iot;
        sc->sc_node = faa->fa_node;

        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;
        }

        printf("\n");

        pinctrl_byname(sc->sc_node, "default");

        clock_enable_all(sc->sc_node);

        clock_speed = clock_get_frequency(sc->sc_node, NULL);
        bus_speed = OF_getpropint(sc->sc_node, "clock-frequency", 100000);

        div = clock_speed / bus_speed;
        if (div & 1)
                div++;
        fedl = MAX(div / 16, 1);
        redl = MAX(div / 4, 1);
        HWRITE4(sc, BSC_DIV, div);
        HWRITE4(sc, BSC_DEL, (fedl << BSC_DEL_FEDL_SHIFT) |
            (redl << BSC_DEL_REDL_SHIFT));

        sc->sc_ic.ic_cookie = sc;
        sc->sc_ic.ic_acquire_bus = bcmbsc_acquire_bus;
        sc->sc_ic.ic_release_bus = bcmbsc_release_bus;
        sc->sc_ic.ic_exec = bcmbsc_exec;

        /* Configure its children */
        memset(&iba, 0, sizeof(iba));
        iba.iba_name = "iic";
        iba.iba_tag = &sc->sc_ic;
        iba.iba_bus_scan = bcmbsc_bus_scan;
        iba.iba_bus_scan_arg = &sc->sc_node;

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

        sc->sc_ib.ib_node = sc->sc_node;
        sc->sc_ib.ib_ic = &sc->sc_ic;
        i2c_register(&sc->sc_ib);
}

int
bcmbsc_acquire_bus(void *cookie, int flags)
{
        struct bcmbsc_softc *sc = cookie;

        HWRITE4(sc, BSC_S, HREAD4(sc, BSC_S));
        HWRITE4(sc, BSC_C, BSC_C_I2CEN | BSC_C_CLEAR);
        return 0;
}

void
bcmbsc_release_bus(void *cookie, int flags)
{
        struct bcmbsc_softc *sc = cookie;

        HWRITE4(sc, BSC_C, BSC_C_CLEAR);
}

int
bcmbsc_wait(struct bcmbsc_softc *sc, uint32_t mask, uint32_t value)
{
        uint32_t stat;
        int timo;

        for (timo = 10000; timo > 0; timo--) {
                stat = HREAD4(sc, BSC_S);
                if ((stat & mask) == value)
                        return 0;
                if (stat & BSC_S_CLKT)
                        return ETIMEDOUT;
                if (stat & BSC_S_ERR)
                        return EIO;
                delay(1);
        }

        return ETIMEDOUT;
}

int
bcmbsc_read(struct bcmbsc_softc *sc, uint8_t *buf, size_t buflen)
{
        int i, error;

        for (i = 0; i < buflen; i++) {
                error = bcmbsc_wait(sc, BSC_S_RXD, BSC_S_RXD);
                if (error)
                        return error;
                buf[i] = HREAD4(sc, BSC_FIFO);
        }

        return 0;
}

int
bcmbsc_write(struct bcmbsc_softc *sc, const uint8_t *buf, size_t buflen)
{
        int i, error;

        for (i = 0; i < buflen; i++) {
                error = bcmbsc_wait(sc, BSC_S_TXD, BSC_S_TXD);
                if (error)
                        return error;
                HWRITE4(sc, BSC_FIFO, buf[i]);
        }

        return 0;
}

int
bcmbsc_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 bcmbsc_softc *sc = cookie;
        uint32_t ctrl = BSC_C_I2CEN | BSC_C_ST;
        int error;

        if (cmdlen + buflen > 65535)
                return EINVAL;

        HWRITE4(sc, BSC_A, addr);

        if (I2C_OP_READ_P(op))
                HWRITE4(sc, BSC_DLEN, cmdlen);
        else
                HWRITE4(sc, BSC_DLEN, cmdlen + buflen);

        if (cmdlen > 0) {
                HWRITE4(sc, BSC_C, ctrl);
                error = bcmbsc_write(sc, cmd, cmdlen);
                if (error)
                        return error;
                if (I2C_OP_READ_P(op))
                        bcmbsc_wait(sc, BSC_S_DONE, BSC_S_DONE);
        }

        if (I2C_OP_READ_P(op)) {
                HWRITE4(sc, BSC_DLEN, buflen);
                HWRITE4(sc, BSC_C, ctrl | BSC_C_READ);
                error = bcmbsc_read(sc, buf, buflen);
                if (error)
                        return error;
        } else {
                if (cmdlen == 0)
                        HWRITE4(sc, BSC_C, ctrl);
                error = bcmbsc_write(sc, buf, buflen);
                if (error)
                        return error;
        }

        return bcmbsc_wait(sc, BSC_S_DONE | BSC_S_TA, BSC_S_DONE);
}

void
bcmbsc_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_is_enabled(node))
                        continue;

                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);
        }
}