/*-
 * Copyright (c) 1998, 2001 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.
 *
 * $FreeBSD: head/sys/dev/iicbus/iicbb.c 232365 2012-03-01 20:58:20Z kan $
 */

/*
 * Generic I2C bit-banging code
 *
 * Example:
 *
 *      iicbus
 *       /  \
 *    iicbb pcf
 *     |  \
 *   bti2c lpbb
 *
 * From Linux I2C generic interface
 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
 *
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/uio.h>

#include <bus/iicbus/iiconf.h>
#include <bus/iicbus/iicbus.h>

#include <bus/smbus/smbconf.h>

#include "iicbus_if.h"
#include "iicbb_if.h"

struct iicbb_softc {
        device_t iicbus;
        int udelay;             /* signal toggle delay in usec */
};

static int iicbb_attach(device_t);
static void iicbb_child_detached(device_t, device_t);
static int iicbb_detach(device_t);
static int iicbb_print_child(device_t, device_t);
static int iicbb_probe(device_t);

static int iicbb_callback(device_t, int, caddr_t);
static int iicbb_start(device_t, u_char, int);
static int iicbb_stop(device_t);
static int iicbb_write(device_t, const char *, int, int *, int);
static int iicbb_read(device_t, char *, int, int *, int, int);
static int iicbb_reset(device_t, u_char, u_char, u_char *);
static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);

static device_method_t iicbb_methods[] = {
        /* device interface */
        DEVMETHOD(device_probe,         iicbb_probe),
        DEVMETHOD(device_attach,        iicbb_attach),
        DEVMETHOD(device_detach,        iicbb_detach),

        /* bus interface */
        DEVMETHOD(bus_child_detached,   iicbb_child_detached),
        DEVMETHOD(bus_print_child,      iicbb_print_child),

        /* iicbus interface */
        DEVMETHOD(iicbus_callback,      iicbb_callback),
        DEVMETHOD(iicbus_start,         iicbb_start),
        DEVMETHOD(iicbus_repeated_start, iicbb_start),
        DEVMETHOD(iicbus_stop,          iicbb_stop),
        DEVMETHOD(iicbus_write,         iicbb_write),
        DEVMETHOD(iicbus_read,          iicbb_read),
        DEVMETHOD(iicbus_reset,         iicbb_reset),
        DEVMETHOD(iicbus_transfer,      iicbb_transfer),

        DEVMETHOD_END
};

driver_t iicbb_driver = {
        "iicbb",
        iicbb_methods,
        sizeof(struct iicbb_softc),
};

devclass_t iicbb_devclass;

static int
iicbb_probe(device_t dev)
{
        device_set_desc(dev, "I2C bit-banging driver");

        return (0);
}

static int
iicbb_attach(device_t dev)
{
        struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);

        sc->iicbus = device_add_child(dev, "iicbus", -1);
        if (!sc->iicbus)
                return (ENXIO);
        sc->udelay = 10;                /* 10 uS default */
        bus_generic_attach(dev);

        return (0);
}

static int
iicbb_detach(device_t dev)
{
        struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
        device_t child;

        /*
         * We need to save child because the detach indirectly causes
         * sc->iicbus to be zeroed.  Since we added the device
         * unconditionally in iicbb_attach, we need to make sure we
         * delete it here.  See iicbb_child_detached.  We need that
         * callback in case newbus detached our children w/o detaching
         * us (say iicbus is a module and unloaded w/o iicbb being
         * unloaded).
         */
        child = sc->iicbus;
        bus_generic_detach(dev);
        if (child)
                device_delete_child(dev, child);

        return (0);
}

static void
iicbb_child_detached( device_t dev, device_t child )
{
        struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);

        if (child == sc->iicbus)
                sc->iicbus = NULL;
}

static int
iicbb_print_child(device_t bus, device_t dev)
{
        int error;
        int retval = 0;
        u_char oldaddr;

        retval += bus_print_child_header(bus, dev);
        /* retrieve the interface I2C address */
        error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
        if (error == IIC_ENOADDR) {
                retval += kprintf(" on %s master-only\n",
                                 device_get_nameunit(bus));
        } else {
                /* restore the address */
                IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);

                retval += kprintf(" on %s addr 0x%x\n",
                                 device_get_nameunit(bus), oldaddr & 0xff);
        }

        return (retval);
}

#define I2C_SETSDA(sc,dev,val) do {                     \
        IICBB_SETSDA(device_get_parent(dev), val);      \
        DELAY(sc->udelay);                              \
        } while (0)

#define I2C_SETSCL(dev,val) do {                        \
        iicbb_setscl(dev, val, 100);                    \
        } while (0)

#define I2C_SET(sc,dev,ctrl,data) do {                  \
        I2C_SETSCL(dev, ctrl);                          \
        I2C_SETSDA(sc, dev, data);                      \
        } while (0)

#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))

#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))

static int i2c_debug = 0;
#define I2C_DEBUG(x)    do {                                    \
                                if (i2c_debug) (x);             \
                        } while (0)

#define I2C_LOG(format,args...) do {                            \
                                        kprintf(format, args);  \
                                } while (0)

static void
iicbb_setscl(device_t dev, int val, int timeout)
{
        struct iicbb_softc *sc = device_get_softc(dev);
        int k = 0;

        IICBB_SETSCL(device_get_parent(dev), val);
        DELAY(sc->udelay);

        while (val && !I2C_GETSCL(dev) && k++ < timeout) {
                IICBB_SETSCL(device_get_parent(dev), val);
                DELAY(sc->udelay);
        }

        return;
}

static void
iicbb_one(device_t dev, int timeout)
{
        struct iicbb_softc *sc = device_get_softc(dev);

        I2C_SET(sc,dev,0,1);
        I2C_SET(sc,dev,1,1);
        I2C_SET(sc,dev,0,1);
        return;
}

static void
iicbb_zero(device_t dev, int timeout)
{
        struct iicbb_softc *sc = device_get_softc(dev);

        I2C_SET(sc,dev,0,0);
        I2C_SET(sc,dev,1,0);
        I2C_SET(sc,dev,0,0);
        return;
}

/*
 * Waiting for ACKNOWLEDGE.
 *
 * When a chip is being addressed or has received data it will issue an
 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 * (set it to high level) and then release the CLOCK line.
 * Now it must wait for the SLAVE to pull the DATA line low.
 * Actually on the bus this looks like a START condition so nothing happens
 * because of the fact that the IC's that have not been addressed are doing
 * nothing.
 *
 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 * line low and then the SLAVE will release the SDA (data) line.
 */
static int
iicbb_ack(device_t dev, int timeout)
{
        struct iicbb_softc *sc = device_get_softc(dev);
        int noack;
        int k = 0;

        I2C_SET(sc,dev,0,1);
        I2C_SET(sc,dev,1,1);
        do {
                noack = I2C_GETSDA(dev);
                if (!noack)
                        break;
                DELAY(1);
                k++;
        } while (k < timeout);

        I2C_SET(sc,dev,0,1);
        I2C_DEBUG(kprintf("%c ",noack?'-':'+'));

        return (noack);
}

static void
iicbb_sendbyte(device_t dev, u_char data, int timeout)
{
        int i;

        for (i=7; i>=0; i--) {
                if (data&(1<<i)) {
                        iicbb_one(dev, timeout);
                } else {
                        iicbb_zero(dev, timeout);
                }
        }
        I2C_DEBUG(kprintf("w%02x",(int)data));
        return;
}

static u_char
iicbb_readbyte(device_t dev, int last, int timeout)
{
        struct iicbb_softc *sc = device_get_softc(dev);
        int i;
        unsigned char data=0;

        I2C_SET(sc,dev,0,1);
        for (i=7; i>=0; i--)
        {
                I2C_SET(sc,dev,1,1);
                if (I2C_GETSDA(dev))
                        data |= (1<<i);
                I2C_SET(sc,dev,0,1);
        }
        if (last) {
                iicbb_one(dev, timeout);
        } else {
                iicbb_zero(dev, timeout);
        }
        I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
        return data;
}

static int
iicbb_callback(device_t dev, int index, caddr_t data)
{
        return (IICBB_CALLBACK(device_get_parent(dev), index, data));
}

static int
iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
{
        return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
}

static int
iicbb_start(device_t dev, u_char slave, int timeout)
{
        struct iicbb_softc *sc = device_get_softc(dev);
        int error;

        I2C_DEBUG(kprintf("<"));

        I2C_SET(sc,dev,1,1);
        I2C_SET(sc,dev,1,0);
        I2C_SET(sc,dev,0,0);

        /* send address */
        iicbb_sendbyte(dev, slave, timeout);

        /* check for ack */
        if (iicbb_ack(dev, timeout)) {
                error = IIC_ENOACK;
                goto error;
        }

        return(0);

error:
        iicbb_stop(dev);
        return (error);
}

static int
iicbb_stop(device_t dev)
{
        struct iicbb_softc *sc = device_get_softc(dev);

        I2C_SET(sc,dev,0,0);
        I2C_SET(sc,dev,1,0);
        I2C_SET(sc,dev,1,1);
        I2C_DEBUG(kprintf(">"));
        I2C_DEBUG(kprintf("\n"));
        return (0);
}

static int
iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
{
        int bytes, error = 0;

        bytes = 0;
        while (len) {
                /* send byte */
                iicbb_sendbyte(dev,(u_char)*buf++, timeout);

                /* check for ack */
                if (iicbb_ack(dev, timeout)) {
                        error = IIC_ENOACK;
                        goto error;
                }
                bytes ++;
                len --;
        }

error:
        *sent = bytes;
        return (error);
}

static int
iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
{
        int bytes;

        bytes = 0;
        while (len) {
                /* XXX should insert delay here */
                *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);

                bytes ++;
                len --;
        }

        *read = bytes;
        return (0);
}

static int
iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
{
        int error;

        error = IICBB_PRE_XFER(device_get_parent(dev));
        if (error)
                return (error);

        error = iicbus_transfer_gen(dev, msgs, nmsgs);

        IICBB_POST_XFER(device_get_parent(dev));
        return (error);
}

DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, NULL, NULL);
DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, NULL, NULL);
DRIVER_MODULE(iicbb, intel_iic, iicbb_driver, iicbb_devclass, NULL, NULL);
DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, NULL, NULL);
DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, NULL, NULL);

MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
MODULE_VERSION(iicbb, IICBB_MODVER);