/*-
 * Copyright (c) 2021 Beckhoff Automation GmbH & Co. KG
 *
 * 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/bus.h>
#include <sys/malloc.h>

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

#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/list.h>
#include <linux/pci.h>

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

static int lkpi_i2c_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
static int lkpi_i2c_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr);

struct lkpi_iic_softc {
        device_t                iicbus;
        struct i2c_adapter      *adapter;
};

static struct sx lkpi_sx_i2c;

static void
lkpi_sysinit_i2c(void *arg __unused)
{

        sx_init(&lkpi_sx_i2c, "lkpi-i2c");
}

static void
lkpi_sysuninit_i2c(void *arg __unused)
{

        sx_destroy(&lkpi_sx_i2c);
}

SYSINIT(lkpi_i2c, SI_SUB_DRIVERS, SI_ORDER_ANY,
    lkpi_sysinit_i2c, NULL);
SYSUNINIT(lkpi_i2c, SI_SUB_DRIVERS, SI_ORDER_ANY,
    lkpi_sysuninit_i2c, NULL);

static int
lkpi_iic_probe(device_t dev)
{

        device_set_desc(dev, "LinuxKPI I2C");
        return (BUS_PROBE_NOWILDCARD);
}

static int
lkpi_iic_attach(device_t dev)
{
        struct lkpi_iic_softc *sc;

        sc = device_get_softc(dev);
        sc->iicbus = device_add_child(dev, "iicbus", DEVICE_UNIT_ANY);
        if (sc->iicbus == NULL) {
                device_printf(dev, "Couldn't add iicbus child, aborting\n");
                return (ENXIO);
        }
        bus_attach_children(dev);
        return (0);
}

static int
lkpi_iic_detach(device_t dev)
{
        struct lkpi_iic_softc *sc;

        sc = device_get_softc(dev);
        if (sc->iicbus)
                device_delete_child(dev, sc->iicbus);
        return (0);
}

static int
lkpi_iic_add_adapter(device_t dev, struct i2c_adapter *adapter)
{
        struct lkpi_iic_softc *sc;

        sc = device_get_softc(dev);
        sc->adapter = adapter;

        return (0);
}

static struct i2c_adapter *
lkpi_iic_get_adapter(device_t dev)
{
        struct lkpi_iic_softc *sc;

        sc = device_get_softc(dev);
        return (sc->adapter);
}

static device_method_t lkpi_iic_methods[] = {
        /* device interface */
        DEVMETHOD(device_probe,         lkpi_iic_probe),
        DEVMETHOD(device_attach,        lkpi_iic_attach),
        DEVMETHOD(device_detach,        lkpi_iic_detach),
        DEVMETHOD(device_suspend,       bus_generic_suspend),
        DEVMETHOD(device_resume,        bus_generic_resume),

        /* iicbus interface */
        DEVMETHOD(iicbus_transfer,      lkpi_i2c_transfer),
        DEVMETHOD(iicbus_reset,         lkpi_i2c_reset),
        DEVMETHOD(iicbus_callback,      iicbus_null_callback),

        /* lkpi_iic interface */
        DEVMETHOD(lkpi_iic_add_adapter, lkpi_iic_add_adapter),
        DEVMETHOD(lkpi_iic_get_adapter, lkpi_iic_get_adapter),

        DEVMETHOD_END
};

driver_t lkpi_iic_driver = {
        "lkpi_iic",
        lkpi_iic_methods,
        sizeof(struct lkpi_iic_softc),
};

DRIVER_MODULE(lkpi_iic, drmn, lkpi_iic_driver, 0, 0);
DRIVER_MODULE(lkpi_iic, drm, lkpi_iic_driver, 0, 0);
DRIVER_MODULE(iicbus, lkpi_iic, iicbus_driver, 0, 0);
MODULE_DEPEND(linuxkpi, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);

static int
lkpi_i2c_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
{

        /* That doesn't seems to be supported in linux */
        return (0);
}

static int i2c_check_for_quirks(struct i2c_adapter *adapter,
    struct iic_msg *msgs, uint32_t nmsgs)
{
        const struct i2c_adapter_quirks *quirks;
        device_t dev;
        int i, max_nmsgs;
        bool check_len;

        dev = adapter->dev.parent->bsddev;
        quirks = adapter->quirks;
        if (quirks == NULL)
                return (0);

        check_len = true;
        max_nmsgs = quirks->max_num_msgs;

        if (quirks->flags & I2C_AQ_COMB) {
                max_nmsgs = 2;

                if (nmsgs == 2) {
                        if (quirks->flags & I2C_AQ_COMB_WRITE_FIRST &&
                            msgs[0].flags & IIC_M_RD) {
                                device_printf(dev,
                                    "Error: "
                                    "first combined message must be write\n");
                                return (EOPNOTSUPP);
                        }
                        if (quirks->flags & I2C_AQ_COMB_READ_SECOND &&
                            !(msgs[1].flags & IIC_M_RD)) {
                                device_printf(dev,
                                    "Error: "
                                    "second combined message must be read\n");
                                return (EOPNOTSUPP);
                        }

                        if (quirks->flags & I2C_AQ_COMB_SAME_ADDR &&
                            msgs[0].slave != msgs[1].slave) {
                                device_printf(dev,
                                    "Error: "
                                    "combined message must be use the same "
                                    "address\n");
                                return (EOPNOTSUPP);
                        }

                        if (quirks->max_comb_1st_msg_len &&
                            msgs[0].len > quirks->max_comb_1st_msg_len) {
                                device_printf(dev,
                                    "Error: "
                                    "message too long: %hu > %hu max\n",
                                    msgs[0].len,
                                    quirks->max_comb_1st_msg_len);
                                return (EOPNOTSUPP);
                        }
                        if (quirks->max_comb_2nd_msg_len &&
                            msgs[1].len > quirks->max_comb_2nd_msg_len) {
                                device_printf(dev,
                                    "Error: "
                                    "message too long: %hu > %hu max\n",
                                    msgs[1].len,
                                    quirks->max_comb_2nd_msg_len);
                                return (EOPNOTSUPP);
                        }

                        check_len = false;
                }
        }

        if (max_nmsgs && nmsgs > max_nmsgs) {
                device_printf(dev,
                    "Error: too many messages: %d > %d max\n",
                    nmsgs, max_nmsgs);
                return (EOPNOTSUPP);
        }

        for (i = 0; i < nmsgs; i++) {
                if (msgs[i].flags & IIC_M_RD) {
                        if (check_len && quirks->max_read_len &&
                            msgs[i].len > quirks->max_read_len) {
                                device_printf(dev,
                                    "Error: "
                                    "message %d too long: %hu > %hu max\n",
                                    i, msgs[i].len, quirks->max_read_len);
                                return (EOPNOTSUPP);
                        }
                        if (quirks->flags & I2C_AQ_NO_ZERO_LEN_READ &&
                            msgs[i].len == 0) {
                                device_printf(dev,
                                    "Error: message %d of length 0\n", i);
                                return (EOPNOTSUPP);
                        }
                } else {
                        if (check_len && quirks->max_write_len &&
                            msgs[i].len > quirks->max_write_len) {
                                device_printf(dev,
                                    "Message %d too long: %hu > %hu max\n",
                                    i, msgs[i].len, quirks->max_write_len);
                                return (EOPNOTSUPP);
                        }
                        if (quirks->flags & I2C_AQ_NO_ZERO_LEN_WRITE &&
                            msgs[i].len == 0) {
                                device_printf(dev,
                                    "Error: message %d of length 0\n", i);
                                return (EOPNOTSUPP);
                        }
                }
        }

        return (0);
}

static int
lkpi_i2c_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
{
        struct lkpi_iic_softc *sc;
        struct i2c_msg *linux_msgs;
        int i, ret = 0;

        sc = device_get_softc(dev);
        if (sc->adapter == NULL)
                return (ENXIO);
        ret = i2c_check_for_quirks(sc->adapter, msgs, nmsgs);
        if (ret != 0)
                return (ret);
        linux_set_current(curthread);

        linux_msgs = malloc(sizeof(struct i2c_msg) * nmsgs,
            M_DEVBUF, M_WAITOK | M_ZERO);

        for (i = 0; i < nmsgs; i++) {
                linux_msgs[i].addr = msgs[i].slave >> 1;
                linux_msgs[i].len = msgs[i].len;
                linux_msgs[i].buf = msgs[i].buf;
                if (msgs[i].flags & IIC_M_RD) {
                        linux_msgs[i].flags |= I2C_M_RD;
                        for (int j = 0; j < msgs[i].len; j++)
                                msgs[i].buf[j] = 0;
                }
                if (msgs[i].flags & IIC_M_NOSTART)
                        linux_msgs[i].flags |= I2C_M_NOSTART;
        }
        ret = i2c_transfer(sc->adapter, linux_msgs, nmsgs);
        free(linux_msgs, M_DEVBUF);

        if (ret < 0)
                return (-ret);
        return (0);
}

int
lkpi_i2c_add_adapter(struct i2c_adapter *adapter)
{
        device_t lkpi_iic;

        if (adapter->name[0] == '\0')
                return (-EINVAL);
        if (bootverbose)
                device_printf(adapter->dev.parent->bsddev,
                    "Adding i2c adapter %s\n", adapter->name);
        sx_xlock(&lkpi_sx_i2c);
        lkpi_iic = device_add_child(adapter->dev.parent->bsddev, "lkpi_iic",
            DEVICE_UNIT_ANY);
        if (lkpi_iic == NULL) {
                device_printf(adapter->dev.parent->bsddev, "Couldn't add lkpi_iic\n");
                sx_xunlock(&lkpi_sx_i2c);
                return (ENXIO);
        }

        bus_topo_lock();
        bus_attach_children(adapter->dev.parent->bsddev);
        bus_topo_unlock();
        LKPI_IIC_ADD_ADAPTER(lkpi_iic, adapter);
        sx_xunlock(&lkpi_sx_i2c);
        return (0);
}

int
lkpi_i2c_del_adapter(struct i2c_adapter *adapter)
{
        device_t child;
        int unit, rv;

        if (adapter == NULL)
                return (-EINVAL);
        if (bootverbose)
                device_printf(adapter->dev.parent->bsddev,
                    "Removing i2c adapter %s\n", adapter->name);
        sx_xlock(&lkpi_sx_i2c);
        unit = 0;
        while ((child = device_find_child(adapter->dev.parent->bsddev, "lkpi_iic", unit++)) != NULL) {

                if (adapter == LKPI_IIC_GET_ADAPTER(child)) {
                        bus_topo_lock();
                        device_delete_child(adapter->dev.parent->bsddev, child);
                        bus_topo_unlock();
                        rv = 0;
                        goto out;
                }
        }

        unit = 0;
        while ((child = device_find_child(adapter->dev.parent->bsddev, "lkpi_iicbb", unit++)) != NULL) {

                if (adapter == LKPI_IIC_GET_ADAPTER(child)) {
                        bus_topo_lock();
                        device_delete_child(adapter->dev.parent->bsddev, child);
                        bus_topo_unlock();
                        rv = 0;
                        goto out;
                }
        }
        rv = -EINVAL;
out:
        sx_xunlock(&lkpi_sx_i2c);
        return (rv);
}