/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1998 Nicolas Souchu
 * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/bus.h>

#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>
#include "iicbus_if.h"

/*
 * Encode a system errno value into the IIC_Exxxxx space by setting the
 * IIC_ERRNO marker bit, so that iic2errno() can turn it back into a plain
 * system errno value later.  This lets controller- and bus-layer code get
 * important system errno values (such as EINTR/ERESTART) back to the caller.
 */
int
errno2iic(int errno)
{
        return ((errno == 0) ? 0 : errno | IIC_ERRNO);
}

/*
 * Translate IIC_Exxxxx status values to vaguely-equivelent errno values.
 */
int
iic2errno(int iic_status)
{
        switch (iic_status) {
        case IIC_NOERR:         return (0);
        case IIC_EBUSERR:       return (EALREADY);
        case IIC_ENOACK:        return (EIO);
        case IIC_ETIMEOUT:      return (ETIMEDOUT);
        case IIC_EBUSBSY:       return (EWOULDBLOCK);
        case IIC_ESTATUS:       return (EPROTO);
        case IIC_EUNDERFLOW:    return (EIO);
        case IIC_EOVERFLOW:     return (EOVERFLOW);
        case IIC_ENOTSUPP:      return (EOPNOTSUPP);
        case IIC_ENOADDR:       return (EADDRNOTAVAIL);
        case IIC_ERESOURCE:     return (ENOMEM);
        default:
                /*
                 * If the high bit is set, that means it's a system errno value
                 * that was encoded into the IIC_Exxxxxx space by setting the
                 * IIC_ERRNO marker bit.  If lots of high-order bits are set,
                 * then it's one of the negative pseudo-errors such as ERESTART
                 * and we return it as-is.  Otherwise it's a plain "small
                 * positive integer" errno, so just remove the IIC_ERRNO marker
                 * bit.  If it's some unknown number without the high bit set,
                 * there isn't much we can do except call it an I/O error.
                 */
                if ((iic_status & IIC_ERRNO) == 0)
                        return (EIO);
                if ((iic_status & 0xFFFF0000) != 0)
                        return (iic_status);
                return (iic_status & ~IIC_ERRNO);
        }
}

/*
 * iicbus_intr()
 */
void
iicbus_intr(device_t bus, int event, char *buf)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);

        /* call owner's intr routine */
        if (sc->owner)
                IICBUS_INTR(sc->owner, event, buf);

        return;
}

static int
iicbus_poll(struct iicbus_softc *sc, int how)
{
        int error;

        IICBUS_ASSERT_LOCKED(sc);
        switch (how & IIC_INTRWAIT) {
        case IIC_WAIT | IIC_INTR:
                error = mtx_sleep(sc, &sc->lock, IICPRI|PCATCH, "iicreq", 0);
                break;

        case IIC_WAIT | IIC_NOINTR:
                error = mtx_sleep(sc, &sc->lock, IICPRI, "iicreq", 0);
                break;

        default:
                return (IIC_EBUSBSY);
        }

        return (errno2iic(error));
}

/*
 * iicbus_request_bus()
 *
 * Allocate the device to perform transfers.
 *
 * how  : IIC_WAIT or IIC_DONTWAIT
 */
int
iicbus_request_bus(device_t bus, device_t dev, int how)
{
        struct iic_reqbus_data reqdata;
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
        int error = 0;

        IICBUS_LOCK(sc);

        for (;;) {
                if (sc->owner == NULL)
                        break;
                if ((how & IIC_RECURSIVE) && sc->owner == dev)
                        break;
                if ((error = iicbus_poll(sc, how)) != 0)
                        break;
        }

        if (error == 0) {
                ++sc->owncount;
                if (sc->owner == NULL) {
                        sc->owner = dev;
                        /*
                         * Mark the device busy while it owns the bus, to
                         * prevent detaching the device, bus, or hardware
                         * controller, until ownership is relinquished.  If the
                         * device is doing IO from its probe method before
                         * attaching, it cannot be busied; mark the bus busy.
                         */
                        if (device_get_state(dev) < DS_ATTACHING)
                                sc->busydev = bus;
                        else
                                sc->busydev = dev;
                        device_busy(sc->busydev);
                        /* 
                         * Drop the lock around the call to the bus driver, it
                         * should be allowed to sleep in the IIC_WAIT case.
                         * Drivers might also need to grab locks that would
                         * cause a LOR if our lock is held.
                         */
                        IICBUS_UNLOCK(sc);
                        /* Ask the underlying layers if the request is ok */
                        reqdata.dev = dev;
                        reqdata.bus = bus;
                        reqdata.flags = how | IIC_REQBUS_DEV;
                        error = IICBUS_CALLBACK(device_get_parent(bus),
                            IIC_REQUEST_BUS, (caddr_t)&reqdata);
                        IICBUS_LOCK(sc);
        
                        if (error != 0) {
                                sc->owner = NULL;
                                sc->owncount = 0;
                                wakeup_one(sc);
                                device_unbusy(sc->busydev);
                        }
                }
        }

        IICBUS_UNLOCK(sc);

        return (error);
}

/*
 * iicbus_release_bus()
 *
 * Release the device allocated with iicbus_request_dev()
 */
int
iicbus_release_bus(device_t bus, device_t dev)
{
        struct iic_reqbus_data reqdata;
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);

        IICBUS_LOCK(sc);

        if (sc->owner != dev) {
                IICBUS_UNLOCK(sc);
                return (IIC_EBUSBSY);
        }

        if (--sc->owncount == 0) {
                /* Drop the lock while informing the low-level driver. */
                IICBUS_UNLOCK(sc);
                reqdata.dev = dev;
                reqdata.bus = bus;
                reqdata.flags = IIC_REQBUS_DEV;
                IICBUS_CALLBACK(device_get_parent(bus), IIC_RELEASE_BUS,
                    (caddr_t)&reqdata);
                IICBUS_LOCK(sc);
                sc->owner = NULL;
                wakeup_one(sc);
                device_unbusy(sc->busydev);
        }
        IICBUS_UNLOCK(sc);
        return (0);
}

/*
 * iicbus_started()
 *
 * Test if the iicbus is started by the controller
 */
int
iicbus_started(device_t bus)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);

        return (sc->started);
}

/*
 * iicbus_start()
 *
 * Send start condition to the slave addressed by 'slave'
 */
int
iicbus_start(device_t bus, u_char slave, int timeout)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
        int error = 0;

        if (sc->started)
                return (IIC_ESTATUS); /* protocol error, bus already started */

        if (!(error = IICBUS_START(device_get_parent(bus), slave, timeout)))
                sc->started = slave;
        else
                sc->started = 0;

        return (error);
}

/*
 * iicbus_repeated_start()
 *
 * Send start condition to the slave addressed by 'slave'
 */
int
iicbus_repeated_start(device_t bus, u_char slave, int timeout)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
        int error = 0;

        if (!sc->started)
                return (IIC_ESTATUS); /* protocol error, bus not started */

        if (!(error = IICBUS_REPEATED_START(device_get_parent(bus), slave, timeout)))
                sc->started = slave;
        else
                sc->started = 0;

        return (error);
}

/*
 * iicbus_stop()
 *
 * Send stop condition to the bus
 */
int
iicbus_stop(device_t bus)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
        int error = 0;

        if (!sc->started)
                return (IIC_ESTATUS); /* protocol error, bus not started */

        error = IICBUS_STOP(device_get_parent(bus));

        /* refuse any further access */
        sc->started = 0;

        return (error);
}

/*
 * iicbus_write()
 *
 * Write a block of data to the slave previously started by
 * iicbus_start() call
 */
int
iicbus_write(device_t bus, const char *buf, int len, int *sent, int timeout)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
        
        /* a slave must have been started for writing */
        if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) != 0))
                return (IIC_ESTATUS);

        return (IICBUS_WRITE(device_get_parent(bus), buf, len, sent, timeout));
}

/*
 * iicbus_read()
 *
 * Read a block of data from the slave previously started by
 * iicbus_read() call
 */
int 
iicbus_read(device_t bus, char *buf, int len, int *read, int last, int delay)
{
        struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
        
        /* a slave must have been started for reading */
        if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) == 0))
                return (IIC_ESTATUS);

        return (IICBUS_READ(device_get_parent(bus), buf, len, read, last, delay));
}

/*
 * iicbus_write_byte()
 *
 * Write a byte to the slave previously started by iicbus_start() call
 */
int
iicbus_write_byte(device_t bus, char byte, int timeout)
{
        struct iicbus_softc *sc = device_get_softc(bus);
        char data = byte;
        int sent;

        /* a slave must have been started for writing */
        if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) != 0))
                return (IIC_ESTATUS);

        return (iicbus_write(bus, &data, 1, &sent, timeout));
}

/*
 * iicbus_read_byte()
 *
 * Read a byte from the slave previously started by iicbus_start() call
 */
int
iicbus_read_byte(device_t bus, char *byte, int timeout)
{
        struct iicbus_softc *sc = device_get_softc(bus);
        int read;

        /* a slave must have been started for reading */
        if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) == 0))
                return (IIC_ESTATUS);

        return (iicbus_read(bus, byte, 1, &read, IIC_LAST_READ, timeout));
}

/*
 * iicbus_block_write()
 *
 * Write a block of data to slave ; start/stop protocol managed
 */
int
iicbus_block_write(device_t bus, u_char slave, char *buf, int len, int *sent)
{
        u_char addr = slave & ~LSB;
        int error;

        if ((error = iicbus_start(bus, addr, 0)))
                return (error);

        error = iicbus_write(bus, buf, len, sent, 0);

        iicbus_stop(bus);

        return (error);
}

/*
 * iicbus_block_read()
 *
 * Read a block of data from slave ; start/stop protocol managed
 */
int
iicbus_block_read(device_t bus, u_char slave, char *buf, int len, int *read)
{
        u_char addr = slave | LSB;
        int error;

        if ((error = iicbus_start(bus, addr, 0)))
                return (error);

        error = iicbus_read(bus, buf, len, read, IIC_LAST_READ, 0);

        iicbus_stop(bus);

        return (error);
}

/*
 * iicbus_transfer()
 *
 * Do an aribtrary number of transfers on the iicbus.  We pass these
 * raw requests to the bridge driver.  If the bridge driver supports
 * them directly, then it manages all the details.  If not, it can use
 * the helper function iicbus_transfer_gen() which will do the
 * transfers at a low level.
 *
 * Pointers passed in as part of iic_msg must be kernel pointers.
 * Callers that have user addresses to manage must do so on their own.
 */
int
iicbus_transfer(device_t bus, struct iic_msg *msgs, uint32_t nmsgs)
{

        return (IICBUS_TRANSFER(device_get_parent(bus), msgs, nmsgs));
}

int
iicbus_transfer_excl(device_t dev, struct iic_msg *msgs, uint32_t nmsgs,
    int how)
{
        device_t bus;
        int error;

        bus = device_get_parent(dev);
        error = iicbus_request_bus(bus, dev, how);
        if (error == 0)
                error = IICBUS_TRANSFER(bus, msgs, nmsgs);
        iicbus_release_bus(bus, dev);
        return (error);
}

/*
 * Generic version of iicbus_transfer that calls the appropriate
 * routines to accomplish this.  See note above about acceptable
 * buffer addresses.
 */
int
iicbus_transfer_gen(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
{
        int i, error, lenread, lenwrote, nkid, rpstart, addr;
        device_t *children, bus;
        bool started;

        if ((error = device_get_children(dev, &children, &nkid)) != 0)
                return (IIC_ERESOURCE);
        if (nkid != 1) {
                free(children, M_TEMP);
                return (IIC_ENOTSUPP);
        }
        bus = children[0];
        rpstart = 0;
        free(children, M_TEMP);
        started = false;
        for (i = 0, error = 0; i < nmsgs && error == 0; i++) {
                addr = msgs[i].slave;
                if (msgs[i].flags & IIC_M_RD)
                        addr |= LSB;
                else
                        addr &= ~LSB;

                if (!(msgs[i].flags & IIC_M_NOSTART)) {
                        if (rpstart)
                                error = iicbus_repeated_start(bus, addr, 0);
                        else
                                error = iicbus_start(bus, addr, 0);
                        if (error != 0)
                                break;
                        started = true;
                }

                if (msgs[i].flags & IIC_M_RD)
                        error = iicbus_read(bus, msgs[i].buf, msgs[i].len,
                            &lenread, IIC_LAST_READ, 0);
                else
                        error = iicbus_write(bus, msgs[i].buf, msgs[i].len,
                            &lenwrote, 0);
                if (error != 0)
                        break;

                if (!(msgs[i].flags & IIC_M_NOSTOP)) {
                        rpstart = 0;
                        iicbus_stop(bus);
                } else {
                        rpstart = 1;    /* Next message gets repeated start */
                }
        }
        if (error != 0 && started)
                iicbus_stop(bus);
        return (error);
}

int
iicdev_readfrom(device_t slavedev, uint8_t regaddr, void *buffer,
    uint16_t buflen, int waithow)
{
        struct iic_msg msgs[2];
        uint8_t slaveaddr;

        /*
         * Two transfers back to back with a repeat-start between them; first we
         * write the address-within-device, then we read from the device.
         */
        slaveaddr = iicbus_get_addr(slavedev);

        msgs[0].slave = slaveaddr;
        msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
        msgs[0].len   = 1;
        msgs[0].buf   = &regaddr;

        msgs[1].slave = slaveaddr;
        msgs[1].flags = IIC_M_RD;
        msgs[1].len   = buflen;
        msgs[1].buf   = buffer;

        return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow));
}

int iicdev_writeto(device_t slavedev, uint8_t regaddr, void *buffer,
    uint16_t buflen, int waithow)
{
        struct iic_msg msg;
        uint8_t local_buffer[32];
        uint8_t *bufptr;
        size_t bufsize;
        int error;

        /*
         * Ideally, we would do two transfers back to back with no stop or start
         * between them using an array of 2 iic_msgs; first we'd write the
         * address byte using the IIC_M_NOSTOP flag, then we write the data
         * using IIC_M_NOSTART, all in a single transfer.  Unfortunately,
         * several i2c hardware drivers don't support that (perhaps because the
         * hardware itself can't support it).  So instead we gather the
         * scattered bytes into a single buffer here before writing them using a
         * single iic_msg.  This function is typically used to write a few bytes
         * at a time, so we try to use a small local buffer on the stack, but
         * fall back to allocating a temporary buffer when necessary.
         */

        bufsize = buflen + 1;
        if (bufsize <= sizeof(local_buffer)) {
                bufptr = local_buffer;
        } else {
                bufptr = malloc(bufsize, M_DEVBUF,
                    (waithow & IIC_WAIT) ? M_WAITOK : M_NOWAIT);
                if (bufptr == NULL)
                        return (errno2iic(ENOMEM));
        }

        bufptr[0] = regaddr;
        memcpy(&bufptr[1], buffer, buflen);

        msg.slave = iicbus_get_addr(slavedev);
        msg.flags = IIC_M_WR;
        msg.len   = bufsize;
        msg.buf   = bufptr;

        error = iicbus_transfer_excl(slavedev, &msg, 1, waithow);

        if (bufptr != local_buffer)
                free(bufptr, M_DEVBUF);

        return (error);
}