/*      $NetBSD: gttwsi_core.c,v 1.20 2025/09/25 13:44:31 thorpej Exp $ */
/*
 * Copyright (c) 2008 Eiji Kawauchi.
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed for the NetBSD Project by
 *      Eiji Kawauchi.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * 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 THE AUTHOR 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.
 */
/*
 * Copyright (c) 2005 Brocade Communcations, inc.
 * All rights reserved.
 *
 * Written by Matt Thomas for Brocade Communcations, Inc.
 *
 * 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.
 * 3. The name of Brocade Communications, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BROCADE COMMUNICATIONS, INC. ``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 EITHER BROCADE COMMUNICATIONS, INC. 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.
 */
//#define TWSI_DEBUG

/*
 * Marvell Two-Wire Serial Interface (aka I2C) master driver
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: gttwsi_core.c,v 1.20 2025/09/25 13:44:31 thorpej Exp $");
#include "locators.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/condvar.h>
#include <sys/device.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/mutex.h>
#include <sys/systm.h>

#include <dev/i2c/i2cvar.h>

#include <dev/i2c/gttwsireg.h>
#include <dev/i2c/gttwsivar.h>

static int      gttwsi_send_start(void *v, int flags);
static int      gttwsi_send_stop(void *v, int flags);
static int      gttwsi_initiate_xfer(void *v, i2c_addr_t addr, int flags);
static int      gttwsi_read_byte(void *v, uint8_t *valp, int flags);
static int      gttwsi_write_byte(void *v, uint8_t val, int flags);

static int      gttwsi_wait(struct gttwsi_softc *, uint32_t, uint32_t,
                            uint32_t, int, const char *);

uint32_t
gttwsi_read_4(struct gttwsi_softc *sc, uint32_t reg)
{
        const uint32_t val = bus_space_read_4(sc->sc_bust, sc->sc_bush,
                                              sc->sc_regmap[reg]);
#ifdef TWSI_DEBUG
        printf("I2C:R:[%" PRIu32 "]%02" PRIxBUSSIZE ":%02" PRIx32 "\n", reg, sc->sc_regmap[reg], val);
#else
        DELAY(TWSI_READ_DELAY);
#endif
        return val;
}

void
gttwsi_write_4(struct gttwsi_softc *sc, uint32_t reg, uint32_t val)
{

        bus_space_write_4(sc->sc_bust, sc->sc_bush, sc->sc_regmap[reg], val);
#ifdef TWSI_DEBUG
        printf("I2C:W:[%" PRIu32 "]%02" PRIxBUSSIZE ":%02" PRIx32 "\n", reg, sc->sc_regmap[reg], val);
#else
        DELAY(TWSI_WRITE_DELAY);
#endif
}

/* ARGSUSED */
void
gttwsi_attach_subr(device_t self, bus_space_tag_t iot, bus_space_handle_t ioh,
                   const bus_size_t *regmap)
{
        struct gttwsi_softc * const sc = device_private(self);

        aprint_naive("\n");
        aprint_normal(": Marvell TWSI controller\n");

        sc->sc_dev = self;
        sc->sc_bust = iot;
        sc->sc_bush = ioh;
        sc->sc_regmap = regmap;

        mutex_init(&sc->sc_mtx, MUTEX_DEFAULT, IPL_BIO);
        cv_init(&sc->sc_cv, device_xname(self));

        sc->sc_started = false;
        iic_tag_init(&sc->sc_i2c);
        sc->sc_i2c.ic_cookie = sc;
        sc->sc_i2c.ic_send_start = gttwsi_send_start;
        sc->sc_i2c.ic_send_stop = gttwsi_send_stop;
        sc->sc_i2c.ic_initiate_xfer = gttwsi_initiate_xfer;
        sc->sc_i2c.ic_read_byte = gttwsi_read_byte;
        sc->sc_i2c.ic_write_byte = gttwsi_write_byte;

        /*
         * Put the controller into Soft Reset.
         */
        /* reset */
        gttwsi_write_4(sc, TWSI_SOFTRESET, SOFTRESET_VAL);
}

void
gttwsi_config_children(device_t self)
{
        struct gttwsi_softc * const sc = device_private(self);

        iicbus_attach(self, &sc->sc_i2c);
}

int
gttwsi_intr(void *arg)
{
        struct gttwsi_softc *sc = arg;
        uint32_t val;

        mutex_enter(&sc->sc_mtx);
        val = gttwsi_read_4(sc, TWSI_CONTROL);
        if (val & CONTROL_IFLG) {
                gttwsi_write_4(sc, TWSI_CONTROL, val & ~CONTROL_INTEN);
                cv_broadcast(&sc->sc_cv);
                mutex_exit(&sc->sc_mtx);
                return 1;       /* handled */
        }
        mutex_exit(&sc->sc_mtx);
        return 0;
}

static int
gttwsi_send_start(void *v, int flags)
{
        struct gttwsi_softc *sc = v;
        int expect;

        if (sc->sc_started)
                expect = STAT_RSCT;
        else
                expect = STAT_SCT;
        sc->sc_started = true;
        return gttwsi_wait(sc, CONTROL_START, expect, 0, flags, "send-start");
}

static int
gttwsi_send_stop(void *v, int flags)
{
        struct gttwsi_softc *sc = v;
        int retry = TWSI_RETRY_COUNT;
        uint32_t control, status;

        sc->sc_started = false;

        /* Interrupt is not generated for STAT_NRS. */
        control = CONTROL_STOP | CONTROL_TWSIEN;
        if (sc->sc_iflg_rwc)
                control |= CONTROL_IFLG;
        gttwsi_write_4(sc, TWSI_CONTROL, control);
        while (retry > 0) {
                if ((status = gttwsi_read_4(sc, TWSI_STATUS)) == STAT_NRS)
                        return 0;
                retry--;
                DELAY(TWSI_STAT_DELAY);
        }

        aprint_error_dev(sc->sc_dev, "send STOP failed, status=0x%02x\n",
                         status);
        return EWOULDBLOCK;
}

static int
gttwsi_initiate_xfer(void *v, i2c_addr_t addr, int flags)
{
        struct gttwsi_softc *sc = v;
        uint32_t data, expect, alt;
        int error, read;

        error = gttwsi_send_start(v, flags);
        if (error)
                return error;

        read = (flags & I2C_F_READ) != 0;
        if (read) {
                expect = STAT_ARBT_AR;
                alt    = STAT_ARBT_ANR;
        } else {
                expect = STAT_AWBT_AR;
                alt    = STAT_AWBT_ANR;
        }

        /*
         * First byte contains whether this xfer is a read or write.
         */
        data = read;
        if (addr > 0x7f) {
                /*
                 * If this is a 10bit request, the first address byte is
                 * 0b11110<b9><b8><r/w>.
                 */
                data |= 0xf0 | ((addr & 0x300) >> 7);
                gttwsi_write_4(sc, TWSI_DATA, data);
                error = gttwsi_wait(sc, 0, expect, alt, flags, "send-addr-10");
                if (error)
                        return error;
                /*
                 * The first address byte has been sent, now to send
                 * the second one.
                 */
                if (read) {
                        expect = STAT_SARBT_AR;
                        alt    = STAT_SARBT_ANR;
                } else {
                        expect = STAT_SAWBT_AR;
                        alt    = STAT_SAWBT_ANR;
                }
                data = (uint8_t)addr;
        } else
                data |= (addr << 1);

        gttwsi_write_4(sc, TWSI_DATA, data);
        return gttwsi_wait(sc, 0, expect, alt, flags, "send-addr");
}

static int
gttwsi_read_byte(void *v, uint8_t *valp, int flags)
{
        struct gttwsi_softc *sc = v;
        int error;

        if (flags & I2C_F_LAST) {
                error = gttwsi_wait(sc, 0, STAT_MRRD_ANT, 0, flags,
                                    "read-last-byte");
        } else {
                error = gttwsi_wait(sc, CONTROL_ACK, STAT_MRRD_AT, 0, flags,
                                    "read-byte");
        }
        if (!error)
                *valp = gttwsi_read_4(sc, TWSI_DATA);
        if ((flags & (I2C_F_LAST | I2C_F_STOP)) == (I2C_F_LAST | I2C_F_STOP))
                error = gttwsi_send_stop(sc, flags);
        return error;
}

static int
gttwsi_write_byte(void *v, uint8_t val, int flags)
{
        struct gttwsi_softc *sc = v;
        int error;

        gttwsi_write_4(sc, TWSI_DATA, val);
        error = gttwsi_wait(sc, 0, STAT_MTDB_AR, 0, flags, "write-byte");
        if (flags & I2C_F_STOP)
                gttwsi_send_stop(sc, flags);
        return error;
}

static int
gttwsi_wait(struct gttwsi_softc *sc, uint32_t control, uint32_t expect,
            uint32_t alt, int flags, const char *what)
{
        uint32_t status;
        int timo, error = 0;

        /*
         * XXX Interrupt-driven mode seems to be horribly broken,
         * XXX at least on AllWinner implementations.  Force polled
         * XXX mode for now.
         */
        flags |= I2C_F_POLL;

        DELAY(5);
        if (!(flags & I2C_F_POLL))
                control |= CONTROL_INTEN;
        if (sc->sc_iflg_rwc)
                control |= CONTROL_IFLG;
        mutex_enter(&sc->sc_mtx);
        gttwsi_write_4(sc, TWSI_CONTROL, control | CONTROL_TWSIEN);

        timo = 0;
        for (;;) {
                control = gttwsi_read_4(sc, TWSI_CONTROL);
                if (control & CONTROL_IFLG)
                        break;
                if (!(flags & I2C_F_POLL)) {
                        error = cv_timedwait(&sc->sc_cv, &sc->sc_mtx, hz);
                        if (error) {
                                break;
                        }
                } else {
                        DELAY(TWSI_RETRY_DELAY);
                        if (timo++ > 1000000)   /* 1sec */
                                break;
                }
        }
        if ((control & CONTROL_IFLG) == 0) {
                /*
                 * error is set by the cv_timedwait() call above in the
                 * non-polled case.
                 */
                if (flags & I2C_F_POLL) {
                        error = EWOULDBLOCK;
                } else {
                        KASSERT(error != 0);
                }
                aprint_error_dev(sc->sc_dev,
                    "gttwsi_wait(): %s timeout%s, control=0x%x, error=%d\n",
                    what, (flags & I2C_F_POLL) ? " (polled)" : "",
                    control, error);
                goto end;
        }
        status = gttwsi_read_4(sc, TWSI_STATUS);
        if (status != expect) {
                /*
                 * In the case of probing for a device, we are expecting
                 * 2 different status codes: the ACK case (device exists),
                 * or the NACK case (device does not exist).  We don't
                 * need to report an error in the later case.
                 */
                if (alt != 0 && status != alt)
                        aprint_error_dev(sc->sc_dev,
                            "unexpected status 0x%x: expect 0x%x\n", status,
                            expect);
                error = EIO;
        }
 end:
        mutex_exit(&sc->sc_mtx);
        return error;
}