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/*

 *  Exynos4210 I2C Bus Serial Interface Emulation

 *

 *  Copyright (C) 2012 Samsung Electronics Co Ltd.

 *    Maksim Kozlov, <m.kozlov@samsung.com>

 *    Igor Mitsyanko, <i.mitsyanko@samsung.com>

 *

 *  This program is free software; you can redistribute it and/or modify it

 *  under the terms of the GNU General Public License as published by the

 *  Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful, but WITHOUT

 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 *  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License

 *  for more details.

 *

 *  You should have received a copy of the GNU General Public License along

 *  with this program; if not, see <http://www.gnu.org/licenses/>.

 *

 */

#include "qemu/timer.h"

#include "sysbus.h"

#include "i2c.h"

#ifndef EXYNOS4_I2C_DEBUG

#define EXYNOS4_I2C_DEBUG                 0

#endif

#define TYPE_EXYNOS4_I2C                  "exynos4210.i2c"

#define EXYNOS4_I2C(obj)                  \

    OBJECT_CHECK(Exynos4210I2CState, (obj), TYPE_EXYNOS4_I2C)

/* Exynos4210 I2C memory map */

#define EXYNOS4_I2C_MEM_SIZE              0x14

#define I2CCON_ADDR                       0x00  /* control register */

#define I2CSTAT_ADDR                      0x04  /* control/status register */

#define I2CADD_ADDR                       0x08  /* address register */

#define I2CDS_ADDR                        0x0c  /* data shift register */

#define I2CLC_ADDR                        0x10  /* line control register */

#define I2CCON_ACK_GEN                    (1 << 7)

#define I2CCON_INTRS_EN                   (1 << 5)

#define I2CCON_INT_PEND                   (1 << 4)

#define EXYNOS4_I2C_MODE(reg)             (((reg) >> 6) & 3)

#define I2C_IN_MASTER_MODE(reg)           (((reg) >> 6) & 2)

#define I2CMODE_MASTER_Rx                 0x2

#define I2CMODE_MASTER_Tx                 0x3

#define I2CSTAT_LAST_BIT                  (1 << 0)

#define I2CSTAT_OUTPUT_EN                 (1 << 4)

#define I2CSTAT_START_BUSY                (1 << 5)

#if EXYNOS4_I2C_DEBUG

#define DPRINT(fmt, args...)              \

    do { fprintf(stderr, "QEMU I2C: "fmt, ## args); } while (0)

static const char *exynos4_i2c_get_regname(unsigned offset)

{

    switch (offset) {

    case I2CCON_ADDR:

        return "I2CCON";

    case I2CSTAT_ADDR:

        return "I2CSTAT";

    case I2CADD_ADDR:

        return "I2CADD";

    case I2CDS_ADDR:

        return "I2CDS";

    case I2CLC_ADDR:

        return "I2CLC";

    default:

        return "[?]";

    }

}

#else

#define DPRINT(fmt, args...)              do { } while (0)

#endif

typedef struct Exynos4210I2CState {

    SysBusDevice busdev;

    MemoryRegion iomem;

    i2c_bus *bus;

    qemu_irq irq;

    uint8_t i2ccon;

    uint8_t i2cstat;

    uint8_t i2cadd;

    uint8_t i2cds;

    uint8_t i2clc;

    bool scl_free;

} Exynos4210I2CState;

static inline void exynos4210_i2c_raise_interrupt(Exynos4210I2CState *s)

{

    if (s->i2ccon & I2CCON_INTRS_EN) {

        s->i2ccon |= I2CCON_INT_PEND;

        qemu_irq_raise(s->irq);

    }

}

static void exynos4210_i2c_data_receive(void *opaque)

{

    Exynos4210I2CState *s = (Exynos4210I2CState *)opaque;

    int ret;

    s->i2cstat &= ~I2CSTAT_LAST_BIT;

    s->scl_free = false;

    ret = i2c_recv(s->bus);

    if (ret < 0 && (s->i2ccon & I2CCON_ACK_GEN)) {

        s->i2cstat |= I2CSTAT_LAST_BIT;  /* Data is not acknowledged */

    } else {

        s->i2cds = ret;

    }

    exynos4210_i2c_raise_interrupt(s);

}

static void exynos4210_i2c_data_send(void *opaque)

{

    Exynos4210I2CState *s = (Exynos4210I2CState *)opaque;

    s->i2cstat &= ~I2CSTAT_LAST_BIT;

    s->scl_free = false;

    if (i2c_send(s->bus, s->i2cds) < 0 && (s->i2ccon & I2CCON_ACK_GEN)) {

        s->i2cstat |= I2CSTAT_LAST_BIT;

    }

    exynos4210_i2c_raise_interrupt(s);

}

static uint64_t exynos4210_i2c_read(void *opaque, hwaddr offset,

                                 unsigned size)

{

    Exynos4210I2CState *s = (Exynos4210I2CState *)opaque;

    uint8_t value;

    switch (offset) {

    case I2CCON_ADDR:

        value = s->i2ccon;

        break;

    case I2CSTAT_ADDR:

        value = s->i2cstat;

        break;

    case I2CADD_ADDR:

        value = s->i2cadd;

        break;

    case I2CDS_ADDR:

        value = s->i2cds;

        s->scl_free = true;

        if (EXYNOS4_I2C_MODE(s->i2cstat) == I2CMODE_MASTER_Rx &&

               (s->i2cstat & I2CSTAT_START_BUSY) &&

               !(s->i2ccon & I2CCON_INT_PEND)) {

            exynos4210_i2c_data_receive(s);

        }

        break;

    case I2CLC_ADDR:

        value = s->i2clc;

        break;

    default:

        value = 0;

        DPRINT("ERROR: Bad read offset 0x%x\n", (unsigned int)offset);

        break;

    }

    DPRINT("read %s [0x%02x] -> 0x%02x\n", exynos4_i2c_get_regname(offset),

            (unsigned int)offset, value);

    return value;

}

static void exynos4210_i2c_write(void *opaque, hwaddr offset,

                              uint64_t value, unsigned size)

{

    Exynos4210I2CState *s = (Exynos4210I2CState *)opaque;

    uint8_t v = value & 0xff;

    DPRINT("write %s [0x%02x] <- 0x%02x\n", exynos4_i2c_get_regname(offset),

            (unsigned int)offset, v);

    switch (offset) {

    case I2CCON_ADDR:

        s->i2ccon = (v & ~I2CCON_INT_PEND) | (s->i2ccon & I2CCON_INT_PEND);

        if ((s->i2ccon & I2CCON_INT_PEND) && !(v & I2CCON_INT_PEND)) {

            s->i2ccon &= ~I2CCON_INT_PEND;

            qemu_irq_lower(s->irq);

            if (!(s->i2ccon & I2CCON_INTRS_EN)) {

                s->i2cstat &= ~I2CSTAT_START_BUSY;

            }

            if (s->i2cstat & I2CSTAT_START_BUSY) {

                if (s->scl_free) {

                    if (EXYNOS4_I2C_MODE(s->i2cstat) == I2CMODE_MASTER_Tx) {

                        exynos4210_i2c_data_send(s);

                    } else if (EXYNOS4_I2C_MODE(s->i2cstat) ==

                            I2CMODE_MASTER_Rx) {

                        exynos4210_i2c_data_receive(s);

                    }

                } else {

                    s->i2ccon |= I2CCON_INT_PEND;

                    qemu_irq_raise(s->irq);

                }

            }

        }

        break;

    case I2CSTAT_ADDR:

        s->i2cstat =

                (s->i2cstat & I2CSTAT_START_BUSY) | (v & ~I2CSTAT_START_BUSY);

        if (!(s->i2cstat & I2CSTAT_OUTPUT_EN)) {

            s->i2cstat &= ~I2CSTAT_START_BUSY;

            s->scl_free = true;

            qemu_irq_lower(s->irq);

            break;

        }

        /* Nothing to do if in i2c slave mode */

        if (!I2C_IN_MASTER_MODE(s->i2cstat)) {

            break;

        }

        if (v & I2CSTAT_START_BUSY) {

            s->i2cstat &= ~I2CSTAT_LAST_BIT;

            s->i2cstat |= I2CSTAT_START_BUSY;    /* Line is busy */

            s->scl_free = false;

            /* Generate start bit and send slave address */

            if (i2c_start_transfer(s->bus, s->i2cds >> 1, s->i2cds & 0x1) &&

                    (s->i2ccon & I2CCON_ACK_GEN)) {

                s->i2cstat |= I2CSTAT_LAST_BIT;

            } else if (EXYNOS4_I2C_MODE(s->i2cstat) == I2CMODE_MASTER_Rx) {

                exynos4210_i2c_data_receive(s);

            }

            exynos4210_i2c_raise_interrupt(s);

        } else {

            i2c_end_transfer(s->bus);

            if (!(s->i2ccon & I2CCON_INT_PEND)) {

                s->i2cstat &= ~I2CSTAT_START_BUSY;

            }

            s->scl_free = true;

        }

        break;

    case I2CADD_ADDR:

        if ((s->i2cstat & I2CSTAT_OUTPUT_EN) == 0) {

            s->i2cadd = v;

        }

        break;

    case I2CDS_ADDR:

        if (s->i2cstat & I2CSTAT_OUTPUT_EN) {

            s->i2cds = v;

            s->scl_free = true;

            if (EXYNOS4_I2C_MODE(s->i2cstat) == I2CMODE_MASTER_Tx &&

                    (s->i2cstat & I2CSTAT_START_BUSY) &&

                    !(s->i2ccon & I2CCON_INT_PEND)) {

                exynos4210_i2c_data_send(s);

            }

        }

        break;

    case I2CLC_ADDR:

        s->i2clc = v;

        break;

    default:

        DPRINT("ERROR: Bad write offset 0x%x\n", (unsigned int)offset);

        break;

    }

}

static const MemoryRegionOps exynos4210_i2c_ops = {

    .read = exynos4210_i2c_read,

    .write = exynos4210_i2c_write,

    .endianness = DEVICE_NATIVE_ENDIAN,

};

static const VMStateDescription exynos4210_i2c_vmstate = {

    .name = TYPE_EXYNOS4_I2C,

    .version_id = 1,

    .minimum_version_id = 1,

    .fields = (VMStateField[]) {

        VMSTATE_UINT8(i2ccon, Exynos4210I2CState),

        VMSTATE_UINT8(i2cstat, Exynos4210I2CState),

        VMSTATE_UINT8(i2cds, Exynos4210I2CState),

        VMSTATE_UINT8(i2cadd, Exynos4210I2CState),

        VMSTATE_UINT8(i2clc, Exynos4210I2CState),

        VMSTATE_BOOL(scl_free, Exynos4210I2CState),

        VMSTATE_END_OF_LIST()

    }

};

static void exynos4210_i2c_reset(DeviceState *d)

{

    Exynos4210I2CState *s = EXYNOS4_I2C(d);

    s->i2ccon  = 0x00;

    s->i2cstat = 0x00;

    s->i2cds   = 0xFF;

    s->i2clc   = 0x00;

    s->i2cadd  = 0xFF;

    s->scl_free = true;

}

static int exynos4210_i2c_realize(SysBusDevice *dev)

{

    Exynos4210I2CState *s = EXYNOS4_I2C(dev);

    memory_region_init_io(&s->iomem, &exynos4210_i2c_ops, s, TYPE_EXYNOS4_I2C,

                          EXYNOS4_I2C_MEM_SIZE);

    sysbus_init_mmio(dev, &s->iomem);

    sysbus_init_irq(dev, &s->irq);

    s->bus = i2c_init_bus(&dev->qdev, "i2c");

    return 0;

}

static void exynos4210_i2c_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    SysBusDeviceClass *sbdc = SYS_BUS_DEVICE_CLASS(klass);

    dc->vmsd = &exynos4210_i2c_vmstate;

    dc->reset = exynos4210_i2c_reset;

    sbdc->init = exynos4210_i2c_realize;

}

static const TypeInfo exynos4210_i2c_type_info = {

    .name = TYPE_EXYNOS4_I2C,

    .parent = TYPE_SYS_BUS_DEVICE,

    .instance_size = sizeof(Exynos4210I2CState),

    .class_init = exynos4210_i2c_class_init,

};

static void exynos4210_i2c_register_types(void)

{

    type_register_static(&exynos4210_i2c_type_info);

}

type_init(exynos4210_i2c_register_types)