/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2008-2009 Semihalf, Michal Hajduk
 * 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 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 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/kernel.h>
#include <sys/module.h>
#include <sys/resource.h>

#include <machine/bus.h>
#include <machine/resource.h>
#include <sys/rman.h>

#include <sys/lock.h>
#include <sys/mutex.h>

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

#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>

#define I2C_ADDR_REG            0x00 /* I2C slave address register */
#define I2C_FDR_REG             0x04 /* I2C frequency divider register */
#define I2C_CONTROL_REG         0x08 /* I2C control register */
#define I2C_STATUS_REG          0x0C /* I2C status register */
#define I2C_DATA_REG            0x10 /* I2C data register */
#define I2C_DFSRR_REG           0x14 /* I2C Digital Filter Sampling rate */
#define I2C_ENABLE              0x80 /* Module enable - interrupt disable */
#define I2CSR_RXAK              0x01 /* Received acknowledge */
#define I2CSR_MCF               (1<<7) /* Data transfer */
#define I2CSR_MASS              (1<<6) /* Addressed as a slave */
#define I2CSR_MBB               (1<<5) /* Bus busy */
#define I2CSR_MAL               (1<<4) /* Arbitration lost */
#define I2CSR_SRW               (1<<2) /* Slave read/write */
#define I2CSR_MIF               (1<<1) /* Module interrupt */
#define I2CCR_MEN               (1<<7) /* Module enable */
#define I2CCR_MSTA              (1<<5) /* Master/slave mode */
#define I2CCR_MTX               (1<<4) /* Transmit/receive mode */
#define I2CCR_TXAK              (1<<3) /* Transfer acknowledge */
#define I2CCR_RSTA              (1<<2) /* Repeated START */

#define I2C_BAUD_RATE_FAST      0x31
#define I2C_BAUD_RATE_DEF       0x3F
#define I2C_DFSSR_DIV           0x10

#ifdef  DEBUG
#define debugf(fmt, args...) do { printf("%s(): ", __func__); printf(fmt,##args); } while (0)
#else
#define debugf(fmt, args...)
#endif

struct i2c_softc {
        device_t                dev;
        device_t                iicbus;
        struct resource         *res;
        struct mtx              mutex;
        int                     rid;
        bus_space_handle_t      bsh;
        bus_space_tag_t         bst;
};

static int i2c_probe(device_t);
static int i2c_attach(device_t);

static int i2c_repeated_start(device_t dev, u_char slave, int timeout);
static int i2c_start(device_t dev, u_char slave, int timeout);
static int i2c_stop(device_t dev);
static int i2c_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr);
static int i2c_read(device_t dev, char *buf, int len, int *read, int last, int delay);
static int i2c_write(device_t dev, const char *buf, int len, int *sent, int timeout);
static phandle_t i2c_get_node(device_t bus, device_t dev);

static device_method_t i2c_methods[] = {
        DEVMETHOD(device_probe,                 i2c_probe),
        DEVMETHOD(device_attach,                i2c_attach),

        DEVMETHOD(iicbus_callback,              iicbus_null_callback),
        DEVMETHOD(iicbus_repeated_start,        i2c_repeated_start),
        DEVMETHOD(iicbus_start,                 i2c_start),
        DEVMETHOD(iicbus_stop,                  i2c_stop),
        DEVMETHOD(iicbus_reset,                 i2c_reset),
        DEVMETHOD(iicbus_read,                  i2c_read),
        DEVMETHOD(iicbus_write,                 i2c_write),
        DEVMETHOD(iicbus_transfer,              iicbus_transfer_gen),
        DEVMETHOD(ofw_bus_get_node,             i2c_get_node),
        { 0, 0 }
};

static driver_t i2c_driver = {
        "iichb",
        i2c_methods,
        sizeof(struct i2c_softc),
};

DRIVER_MODULE(i2c, simplebus, i2c_driver, 0, 0);
DRIVER_MODULE(iicbus, i2c, iicbus_driver, 0, 0);

static __inline void
i2c_write_reg(struct i2c_softc *sc, bus_size_t off, uint8_t val)
{

        bus_space_write_1(sc->bst, sc->bsh, off, val);
}

static __inline uint8_t
i2c_read_reg(struct i2c_softc *sc, bus_size_t off)
{

        return (bus_space_read_1(sc->bst, sc->bsh, off));
}

static __inline void
i2c_flag_set(struct i2c_softc *sc, bus_size_t off, uint8_t mask)
{
        uint8_t status;

        status = i2c_read_reg(sc, off);
        status |= mask;
        i2c_write_reg(sc, off, status);
}

static int
i2c_do_wait(device_t dev, struct i2c_softc *sc, int write, int start)
{
        int err;
        uint8_t status;

        status = i2c_read_reg(sc, I2C_STATUS_REG);
        if (status & I2CSR_MIF) {
                if (write && start && (status & I2CSR_RXAK)) {
                        debugf("no ack %s", start ?
                            "after sending slave address" : "");
                        err = IIC_ENOACK;
                        goto error;
                }
                if (status & I2CSR_MAL) {
                        debugf("arbitration lost");
                        err = IIC_EBUSERR;
                        goto error;
                }
                if (!write && !(status & I2CSR_MCF)) {
                        debugf("transfer unfinished");
                        err = IIC_EBUSERR;
                        goto error;
                }
        }

        return (IIC_NOERR);

error:
        i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
        i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN | I2CCR_TXAK);
        return (err);
}

static int
i2c_probe(device_t dev)
{
        struct i2c_softc *sc;

        if (!ofw_bus_is_compatible(dev, "fsl-i2c"))
                return (ENXIO);

        sc = device_get_softc(dev);
        sc->rid = 0;

        sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid,
            RF_ACTIVE);
        if (sc->res == NULL) {
                device_printf(dev, "could not allocate resources\n");
                return (ENXIO);
        }

        sc->bst = rman_get_bustag(sc->res);
        sc->bsh = rman_get_bushandle(sc->res);

        /* Enable I2C */
        i2c_write_reg(sc, I2C_CONTROL_REG, I2C_ENABLE);
        bus_release_resource(dev, SYS_RES_MEMORY, sc->rid, sc->res);
        device_set_desc(dev, "I2C bus controller");

        return (BUS_PROBE_DEFAULT);
}

static int
i2c_attach(device_t dev)
{
        struct i2c_softc *sc;
        sc = device_get_softc(dev);

        sc->dev = dev;
        sc->rid = 0;

        mtx_init(&sc->mutex, device_get_nameunit(dev), "I2C", MTX_DEF);

        sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid,
            RF_ACTIVE);
        if (sc->res == NULL) {
                device_printf(dev, "could not allocate resources");
                mtx_destroy(&sc->mutex);
                return (ENXIO);
        }

        sc->bst = rman_get_bustag(sc->res);
        sc->bsh = rman_get_bushandle(sc->res);

        sc->iicbus = device_add_child(dev, "iicbus", DEVICE_UNIT_ANY);
        if (sc->iicbus == NULL) {
                device_printf(dev, "could not add iicbus child");
                mtx_destroy(&sc->mutex);
                return (ENXIO);
        }

        bus_attach_children(dev);
        return (IIC_NOERR);
}
static int
i2c_repeated_start(device_t dev, u_char slave, int timeout)
{
        struct i2c_softc *sc;
        int error;

        sc = device_get_softc(dev);

        mtx_lock(&sc->mutex);
        /* Set repeated start condition */
        i2c_flag_set(sc, I2C_CONTROL_REG ,I2CCR_RSTA);
        /* Write target address - LSB is R/W bit */
        i2c_write_reg(sc, I2C_DATA_REG, slave);
        DELAY(1250);

        error = i2c_do_wait(dev, sc, 1, 1);
        mtx_unlock(&sc->mutex);

        if (error)
                return (error);

        return (IIC_NOERR);
}

static int
i2c_start(device_t dev, u_char slave, int timeout)
{
        struct i2c_softc *sc;
        uint8_t status;
        int error;

        sc = device_get_softc(dev);
        DELAY(1000);

        mtx_lock(&sc->mutex);
        status = i2c_read_reg(sc, I2C_STATUS_REG);
        /* Check if bus is idle or busy */
        if (status & I2CSR_MBB) {
                debugf("bus busy");
                mtx_unlock(&sc->mutex);
                i2c_stop(dev);
                return (IIC_EBUSERR);
        }

        /* Set start condition */
        i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN | I2CCR_MSTA | I2CCR_MTX);
        /* Write target address - LSB is R/W bit */
        i2c_write_reg(sc, I2C_DATA_REG, slave);
        DELAY(1250);

        error = i2c_do_wait(dev, sc, 1, 1);

        mtx_unlock(&sc->mutex);
        if (error)
                return (error);

        return (IIC_NOERR);
}

static int
i2c_stop(device_t dev)
{
        struct i2c_softc *sc;

        sc = device_get_softc(dev);
        mtx_lock(&sc->mutex);
        i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN | I2CCR_TXAK);
        DELAY(1000);
        mtx_unlock(&sc->mutex);

        return (IIC_NOERR);
}

static int
i2c_reset(device_t dev, u_char speed, u_char addr, u_char *oldadr)
{
        struct i2c_softc *sc;
        uint8_t baud_rate;

        sc = device_get_softc(dev);

        switch (speed) {
        case IIC_FAST:
                baud_rate = I2C_BAUD_RATE_FAST;
                break;
        case IIC_SLOW:
        case IIC_UNKNOWN:
        case IIC_FASTEST:
        default:
                baud_rate = I2C_BAUD_RATE_DEF;
                break;
        }

        mtx_lock(&sc->mutex);
        i2c_write_reg(sc, I2C_CONTROL_REG, 0x0);
        i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
        DELAY(1000);
        i2c_write_reg(sc, I2C_FDR_REG, baud_rate);
        i2c_write_reg(sc, I2C_DFSRR_REG, I2C_DFSSR_DIV);
        i2c_write_reg(sc, I2C_CONTROL_REG, I2C_ENABLE);
        DELAY(1000);
        mtx_unlock(&sc->mutex);

        return (IIC_NOERR);
}

static int
i2c_read(device_t dev, char *buf, int len, int *read, int last, int delay)
{
        struct i2c_softc *sc;
        int error;

        sc = device_get_softc(dev);
        *read = 0;

        mtx_lock(&sc->mutex);
        if (len) {
                if (len == 1)
                        i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
                            I2CCR_MSTA | I2CCR_TXAK);

                else
                        i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
                            I2CCR_MSTA);

                /* dummy read */
                i2c_read_reg(sc, I2C_DATA_REG);
                DELAY(1000);
        }

        while (*read < len) {
                DELAY(1000);
                error = i2c_do_wait(dev, sc, 0, 0);
                if (error) {
                        mtx_unlock(&sc->mutex);
                        return (error);
                }
                if ((*read == len - 2) && last) {
                        i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
                            I2CCR_MSTA | I2CCR_TXAK);
                }

                if ((*read == len - 1) && last) {
                        i2c_write_reg(sc, I2C_CONTROL_REG,  I2CCR_MEN |
                            I2CCR_TXAK);
                }

                *buf++ = i2c_read_reg(sc, I2C_DATA_REG);
                (*read)++;
                DELAY(1250);
        }
        mtx_unlock(&sc->mutex);

        return (IIC_NOERR);
}

static int
i2c_write(device_t dev, const char *buf, int len, int *sent, int timeout)
{
        struct i2c_softc *sc;
        int error;

        sc = device_get_softc(dev);
        *sent = 0;

        mtx_lock(&sc->mutex);
        while (*sent < len) {
                i2c_write_reg(sc, I2C_DATA_REG, *buf++);
                DELAY(1250);

                error = i2c_do_wait(dev, sc, 1, 0);
                if (error) {
                        mtx_unlock(&sc->mutex);
                        return (error);
                }

                (*sent)++;
        }
        mtx_unlock(&sc->mutex);

        return (IIC_NOERR);
}

static phandle_t
i2c_get_node(device_t bus, device_t dev)
{

        /* Share controller node with iibus device. */
        return (ofw_bus_get_node(bus));
}