xref: /qemu/hw/i2c/aspeed_i2c.c (revision 06b40d250ecfa1633209c2e431a7a38acfd03a98)

/*
 * ARM Aspeed I2C controller
 *
 * Copyright (C) 2016 IBM Corp.
 *
 * 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/osdep.h"
#include "hw/sysbus.h"
#include "migration/vmstate.h"
#include "qemu/cutils.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "hw/i2c/aspeed_i2c.h"
#include "hw/irq.h"
#include "hw/qdev-properties.h"
#include "hw/registerfields.h"
#include "trace.h"

/* Enable SLAVE_ADDR_RX_MATCH always */
#define R_I2CD_INTR_STS_ALWAYS_ENABLE  R_I2CD_INTR_STS_SLAVE_ADDR_RX_MATCH_MASK

static inline void aspeed_i2c_bus_raise_interrupt(AspeedI2CBus *bus)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
    uint32_t intr_ctrl_reg = aspeed_i2c_bus_intr_ctrl_offset(bus);
    uint32_t intr_ctrl_mask = bus->regs[intr_ctrl_reg] |
        R_I2CD_INTR_STS_ALWAYS_ENABLE;
    bool raise_irq;

    if (trace_event_get_state_backends(TRACE_ASPEED_I2C_BUS_RAISE_INTERRUPT)) {
        g_autofree char *buf = g_strdup_printf("%s%s%s%s%s%s%s",
               aspeed_i2c_bus_pkt_mode_en(bus) &&
               ARRAY_FIELD_EX32(bus->regs, I2CM_INTR_STS, PKT_CMD_DONE) ?
                                               "pktdone|" : "",
               SHARED_ARRAY_FIELD_EX32(bus->regs, reg_intr_sts, TX_NAK) ?
                                               "nak|" : "",
               SHARED_ARRAY_FIELD_EX32(bus->regs, reg_intr_sts, TX_ACK) ?
                                               "ack|" : "",
               SHARED_ARRAY_FIELD_EX32(bus->regs, reg_intr_sts, RX_DONE) ?
                                               "done|" : "",
               ARRAY_FIELD_EX32(bus->regs, I2CD_INTR_STS, SLAVE_ADDR_RX_MATCH) ?
                                               "slave-match|" : "",
               SHARED_ARRAY_FIELD_EX32(bus->regs, reg_intr_sts, NORMAL_STOP) ?
                                               "stop|" : "",
               SHARED_ARRAY_FIELD_EX32(bus->regs, reg_intr_sts, ABNORMAL) ?
                                               "abnormal"  : "");

           trace_aspeed_i2c_bus_raise_interrupt(bus->regs[reg_intr_sts], buf);
    }

    raise_irq = bus->regs[reg_intr_sts] & intr_ctrl_mask ;

    /* In packet mode we don't mask off INTR_STS */
    if (!aspeed_i2c_bus_pkt_mode_en(bus)) {
        bus->regs[reg_intr_sts] &= intr_ctrl_mask;
    }

    if (raise_irq) {
        bus->controller->intr_status |= 1 << bus->id;
        qemu_irq_raise(aic->bus_get_irq(bus));
    }
}

static inline void aspeed_i2c_bus_raise_slave_interrupt(AspeedI2CBus *bus)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);

    if (!bus->regs[R_I2CS_INTR_STS]) {
        return;
    }

    bus->controller->intr_status |= 1 << bus->id;
    qemu_irq_raise(aic->bus_get_irq(bus));
}

static uint64_t aspeed_i2c_bus_old_read(AspeedI2CBus *bus, hwaddr offset,
                                        unsigned size)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    uint64_t value = bus->regs[offset / sizeof(*bus->regs)];

    switch (offset) {
    case A_I2CD_FUN_CTRL:
    case A_I2CD_AC_TIMING1:
    case A_I2CD_AC_TIMING2:
    case A_I2CD_INTR_CTRL:
    case A_I2CD_INTR_STS:
    case A_I2CD_DEV_ADDR:
    case A_I2CD_POOL_CTRL:
    case A_I2CD_BYTE_BUF:
        /* Value is already set, don't do anything. */
        break;
    case A_I2CD_CMD:
        value = SHARED_FIELD_DP32(value, BUS_BUSY_STS, i2c_bus_busy(bus->bus));
        break;
    case A_I2CD_DMA_ADDR:
        if (!aic->has_dma) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA support\n",  __func__);
            value = -1;
            break;
        }

        value = extract64(bus->dma_dram_offset, 0, 32);
        break;
    case A_I2CD_DMA_LEN:
        if (!aic->has_dma) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA support\n",  __func__);
            value = -1;
        }
        break;

    default:
        qemu_log_mask(LOG_GUEST_ERROR,
                      "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, offset);
        value = -1;
        break;
    }

    trace_aspeed_i2c_bus_read(bus->id, offset, size, value);
    return value;
}

static uint64_t aspeed_i2c_bus_new_read(AspeedI2CBus *bus, hwaddr offset,
                                        unsigned size)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    uint64_t value = bus->regs[offset / sizeof(*bus->regs)];

    switch (offset) {
    case A_I2CC_FUN_CTRL:
    case A_I2CC_AC_TIMING:
    case A_I2CC_POOL_CTRL:
    case A_I2CM_INTR_CTRL:
    case A_I2CM_INTR_STS:
    case A_I2CC_MS_TXRX_BYTE_BUF:
    case A_I2CM_DMA_LEN:
    case A_I2CM_DMA_TX_ADDR:
    case A_I2CM_DMA_RX_ADDR:
    case A_I2CM_DMA_LEN_STS:
    case A_I2CC_DMA_LEN:
    case A_I2CS_DEV_ADDR:
    case A_I2CS_DMA_RX_ADDR:
    case A_I2CS_DMA_LEN:
    case A_I2CS_CMD:
    case A_I2CS_INTR_CTRL:
    case A_I2CS_DMA_LEN_STS:
        /* Value is already set, don't do anything. */
        break;
    case A_I2CC_DMA_ADDR:
        value = extract64(bus->dma_dram_offset, 0, 32);
        break;
    case A_I2CS_INTR_STS:
        break;
    case A_I2CM_CMD:
        value = SHARED_FIELD_DP32(value, BUS_BUSY_STS, i2c_bus_busy(bus->bus));
        break;
    case A_I2CM_DMA_TX_ADDR_HI:
    case A_I2CM_DMA_RX_ADDR_HI:
    case A_I2CS_DMA_TX_ADDR_HI:
    case A_I2CS_DMA_RX_ADDR_HI:
        if (!aic->has_dma64) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA 64 bits support\n",
            __func__);
            value = -1;
        }
        break;
    default:
        qemu_log_mask(LOG_GUEST_ERROR,
                      "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, offset);
        value = -1;
        break;
    }

    trace_aspeed_i2c_bus_read(bus->id, offset, size, value);
    return value;
}

static uint64_t aspeed_i2c_bus_read(void *opaque, hwaddr offset,
                                    unsigned size)
{
    AspeedI2CBus *bus = opaque;
    if (aspeed_i2c_is_new_mode(bus->controller)) {
        return aspeed_i2c_bus_new_read(bus, offset, size);
    }
    return aspeed_i2c_bus_old_read(bus, offset, size);
}

static void aspeed_i2c_set_state(AspeedI2CBus *bus, uint8_t state)
{
    if (aspeed_i2c_is_new_mode(bus->controller)) {
        SHARED_ARRAY_FIELD_DP32(bus->regs, R_I2CC_MS_TXRX_BYTE_BUF, TX_STATE,
                                state);
    } else {
        SHARED_ARRAY_FIELD_DP32(bus->regs, R_I2CD_CMD, TX_STATE, state);
    }
}

static uint8_t aspeed_i2c_get_state(AspeedI2CBus *bus)
{
    if (aspeed_i2c_is_new_mode(bus->controller)) {
        return SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CC_MS_TXRX_BYTE_BUF,
                                       TX_STATE);
    }
    return SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CD_CMD, TX_STATE);
}

static int aspeed_i2c_dma_read(AspeedI2CBus *bus, uint8_t *data)
{
    MemTxResult result;
    AspeedI2CState *s = bus->controller;
    uint32_t reg_dma_len = aspeed_i2c_bus_dma_len_offset(bus);

    result = address_space_read(&s->dram_as, bus->dma_dram_offset,
                                MEMTXATTRS_UNSPECIFIED, data, 1);
    if (result != MEMTX_OK) {
        qemu_log_mask(LOG_GUEST_ERROR,
                      "%s: DRAM read failed @%" PRIx64 "\n",
                      __func__, bus->dma_dram_offset);
        return -1;
    }

    bus->dma_dram_offset++;
    bus->regs[reg_dma_len]--;
    return 0;
}

static int aspeed_i2c_bus_send(AspeedI2CBus *bus)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    int ret = -1;
    int i;
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
    uint32_t reg_pool_ctrl = aspeed_i2c_bus_pool_ctrl_offset(bus);
    uint32_t reg_byte_buf = aspeed_i2c_bus_byte_buf_offset(bus);
    uint32_t reg_dma_len = aspeed_i2c_bus_dma_len_offset(bus);
    int pool_tx_count = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_pool_ctrl,
                                                TX_COUNT) + 1;

    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN)) {
        for (i = 0; i < pool_tx_count; i++) {
            uint8_t *pool_base = aic->bus_pool_base(bus);

            trace_aspeed_i2c_bus_send("BUF", i + 1, pool_tx_count,
                                      pool_base[i]);
            ret = i2c_send(bus->bus, pool_base[i]);
            if (ret) {
                break;
            }
        }
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, TX_BUFF_EN, 0);
    } else if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN)) {
        /* In new mode, clear how many bytes we TXed */
        if (aspeed_i2c_is_new_mode(bus->controller)) {
            ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN_STS, TX_LEN, 0);
        }
        while (bus->regs[reg_dma_len]) {
            uint8_t data;
            aspeed_i2c_dma_read(bus, &data);
            trace_aspeed_i2c_bus_send("DMA", bus->regs[reg_dma_len],
                                      bus->regs[reg_dma_len], data);
            ret = i2c_send(bus->bus, data);
            if (ret) {
                break;
            }
            /* In new mode, keep track of how many bytes we TXed */
            if (aspeed_i2c_is_new_mode(bus->controller)) {
                ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN_STS, TX_LEN,
                                 ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN_STS,
                                                  TX_LEN) + 1);
            }
        }
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, TX_DMA_EN, 0);
    } else {
        trace_aspeed_i2c_bus_send("BYTE", 0, 1,
                                  bus->regs[reg_byte_buf]);
        ret = i2c_send(bus->bus, bus->regs[reg_byte_buf]);
    }

    return ret;
}

static void aspeed_i2c_bus_recv(AspeedI2CBus *bus)
{
    AspeedI2CState *s = bus->controller;
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(s);
    uint8_t data;
    int i;
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
    uint32_t reg_pool_ctrl = aspeed_i2c_bus_pool_ctrl_offset(bus);
    uint32_t reg_byte_buf = aspeed_i2c_bus_byte_buf_offset(bus);
    uint32_t reg_dma_len = aspeed_i2c_bus_dma_len_offset(bus);
    int pool_rx_count = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_pool_ctrl,
                                                RX_SIZE) + 1;

    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_BUFF_EN)) {
        uint8_t *pool_base = aic->bus_pool_base(bus);
        if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_pool_ctrl,
                                    BUF_ORGANIZATION)) {
            pool_base += 16;
        }

        for (i = 0; i < pool_rx_count; i++) {
            pool_base[i] = i2c_recv(bus->bus);
            trace_aspeed_i2c_bus_recv("BUF", i + 1, pool_rx_count,
                                      pool_base[i]);
        }

        /* Update RX count */
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_pool_ctrl, RX_COUNT, i & 0xff);
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, RX_BUFF_EN, 0);
    } else if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_DMA_EN)) {
        /* In new mode, clear how many bytes we RXed */
        if (aspeed_i2c_is_new_mode(bus->controller)) {
            ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN_STS, RX_LEN, 0);
        }

        while (bus->regs[reg_dma_len]) {
            MemTxResult result;

            data = i2c_recv(bus->bus);
            trace_aspeed_i2c_bus_recv("DMA", bus->regs[reg_dma_len],
                                      bus->regs[reg_dma_len], data);

            result = address_space_write(&s->dram_as, bus->dma_dram_offset,
                                         MEMTXATTRS_UNSPECIFIED, &data, 1);
            if (result != MEMTX_OK) {
                qemu_log_mask(LOG_GUEST_ERROR,
                              "%s: DRAM write failed @%" PRIx64 "\n",
                              __func__, bus->dma_dram_offset);
                return;
            }

            bus->dma_dram_offset++;
            bus->regs[reg_dma_len]--;
            /* In new mode, keep track of how many bytes we RXed */
            if (aspeed_i2c_is_new_mode(bus->controller)) {
                ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN_STS, RX_LEN,
                                 ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN_STS,
                                                  RX_LEN) + 1);
            }
        }
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, RX_DMA_EN, 0);
    } else {
        data = i2c_recv(bus->bus);
        trace_aspeed_i2c_bus_recv("BYTE", 1, 1, bus->regs[reg_byte_buf]);
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_byte_buf, RX_BUF, data);
    }
}

static void aspeed_i2c_handle_rx_cmd(AspeedI2CBus *bus)
{
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
    uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);

    aspeed_i2c_set_state(bus, I2CD_MRXD);
    aspeed_i2c_bus_recv(bus);
    SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, RX_DONE, 1);
    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_S_RX_CMD_LAST)) {
        i2c_nack(bus->bus);
    }
    SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_RX_CMD, 0);
    SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_S_RX_CMD_LAST, 0);
    aspeed_i2c_set_state(bus, I2CD_MACTIVE);
}

static uint8_t aspeed_i2c_get_addr(AspeedI2CBus *bus)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    uint32_t reg_byte_buf = aspeed_i2c_bus_byte_buf_offset(bus);
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);

    if (aspeed_i2c_bus_pkt_mode_en(bus)) {
        return (ARRAY_FIELD_EX32(bus->regs, I2CM_CMD, PKT_DEV_ADDR) << 1) |
                SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_RX_CMD);
    }
    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN)) {
        uint8_t *pool_base = aic->bus_pool_base(bus);

        return pool_base[0];
    } else if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN)) {
        uint8_t data;

        aspeed_i2c_dma_read(bus, &data);
        return data;
    } else {
        return bus->regs[reg_byte_buf];
    }
}

static bool aspeed_i2c_check_sram(AspeedI2CBus *bus)
{
    AspeedI2CState *s = bus->controller;
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(s);
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
    bool dma_en = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_DMA_EN)  ||
                  SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN)  ||
                  SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_BUFF_EN) ||
                  SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN);
    if (!aic->check_sram) {
        return true;
    }

    /*
     * AST2500: SRAM must be enabled before using the Buffer Pool or
     * DMA mode.
     */
    if (!FIELD_EX32(s->ctrl_global, I2C_CTRL_GLOBAL, SRAM_EN) && dma_en) {
        qemu_log_mask(LOG_GUEST_ERROR, "%s: SRAM is not enabled\n", __func__);
        return false;
    }

    return true;
}

static void aspeed_i2c_bus_cmd_dump(AspeedI2CBus *bus)
{
    g_autofree char *cmd_flags = NULL;
    uint32_t count;
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
    uint32_t reg_pool_ctrl = aspeed_i2c_bus_pool_ctrl_offset(bus);
    uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
    uint32_t reg_dma_len = aspeed_i2c_bus_dma_len_offset(bus);
    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_BUFF_EN)) {
        count = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_pool_ctrl, TX_COUNT) + 1;
    } else if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_DMA_EN)) {
        count = bus->regs[reg_dma_len];
    } else { /* BYTE mode */
        count = 1;
    }

    cmd_flags = g_strdup_printf("%s%s%s%s%s%s%s%s%s",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_START_CMD) ? "start|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_DMA_EN) ? "rxdma|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN) ? "txdma|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, RX_BUFF_EN) ? "rxbuf|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN) ? "txbuf|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_TX_CMD) ? "tx|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_RX_CMD) ? "rx|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_S_RX_CMD_LAST) ? "last|" : "",
    SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_STOP_CMD) ? "stop|" : "");

    trace_aspeed_i2c_bus_cmd(bus->regs[reg_cmd], cmd_flags, count,
                             bus->regs[reg_intr_sts]);
}

/*
 * The state machine needs some refinement. It is only used to track
 * invalid STOP commands for the moment.
 */
static void aspeed_i2c_bus_handle_cmd(AspeedI2CBus *bus, uint64_t value)
{
    uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
    uint32_t reg_cmd = aspeed_i2c_bus_cmd_offset(bus);
    uint32_t reg_dma_len = aspeed_i2c_bus_dma_len_offset(bus);

    if (!aspeed_i2c_check_sram(bus)) {
        return;
    }

    if (trace_event_get_state_backends(TRACE_ASPEED_I2C_BUS_CMD)) {
        aspeed_i2c_bus_cmd_dump(bus);
    }

    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_START_CMD)) {
        uint8_t state = aspeed_i2c_get_state(bus) & I2CD_MACTIVE ?
            I2CD_MSTARTR : I2CD_MSTART;
        uint8_t addr;

        aspeed_i2c_set_state(bus, state);

        addr = aspeed_i2c_get_addr(bus);
        if (i2c_start_transfer(bus->bus, extract32(addr, 1, 7),
                               extract32(addr, 0, 1))) {
            SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, TX_NAK, 1);
            if (aspeed_i2c_bus_pkt_mode_en(bus)) {
                ARRAY_FIELD_DP32(bus->regs, I2CM_INTR_STS, PKT_CMD_FAIL, 1);
            }
        } else {
            /* START doesn't set TX_ACK in packet mode */
            if (!aspeed_i2c_bus_pkt_mode_en(bus)) {
                SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, TX_ACK, 1);
            }
        }

        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_START_CMD, 0);

        if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_DMA_EN)) {
            if (bus->regs[reg_dma_len] == 0) {
                SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_TX_CMD, 0);
            }
        } else if (!SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, TX_BUFF_EN)) {
            SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_TX_CMD, 0);
        }

        /* No slave found */
        if (!i2c_bus_busy(bus->bus)) {
            if (aspeed_i2c_bus_pkt_mode_en(bus)) {
                ARRAY_FIELD_DP32(bus->regs, I2CM_INTR_STS, PKT_CMD_FAIL, 1);
                ARRAY_FIELD_DP32(bus->regs, I2CM_INTR_STS, PKT_CMD_DONE, 1);
            }
            return;
        }
        aspeed_i2c_set_state(bus, I2CD_MACTIVE);
    }

    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_TX_CMD)) {
        aspeed_i2c_set_state(bus, I2CD_MTXD);
        if (aspeed_i2c_bus_send(bus)) {
            SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, TX_NAK, 1);
            i2c_end_transfer(bus->bus);
        } else {
            SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, TX_ACK, 1);
        }
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_TX_CMD, 0);
        aspeed_i2c_set_state(bus, I2CD_MACTIVE);
    }

    if ((SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_RX_CMD) ||
         SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_S_RX_CMD_LAST)) &&
        !SHARED_ARRAY_FIELD_EX32(bus->regs, reg_intr_sts, RX_DONE)) {
        aspeed_i2c_handle_rx_cmd(bus);
    }

    if (SHARED_ARRAY_FIELD_EX32(bus->regs, reg_cmd, M_STOP_CMD)) {
        if (!(aspeed_i2c_get_state(bus) & I2CD_MACTIVE)) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: abnormal stop\n", __func__);
            SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, ABNORMAL, 1);
            if (aspeed_i2c_bus_pkt_mode_en(bus)) {
                ARRAY_FIELD_DP32(bus->regs, I2CM_INTR_STS, PKT_CMD_FAIL, 1);
            }
        } else {
            aspeed_i2c_set_state(bus, I2CD_MSTOP);
            i2c_end_transfer(bus->bus);
            SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, NORMAL_STOP, 1);
        }
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_cmd, M_STOP_CMD, 0);
        aspeed_i2c_set_state(bus, I2CD_IDLE);

        i2c_schedule_pending_master(bus->bus);
    }

    if (aspeed_i2c_bus_pkt_mode_en(bus)) {
        ARRAY_FIELD_DP32(bus->regs, I2CM_INTR_STS, PKT_CMD_DONE, 1);
    }
}

static void aspeed_i2c_bus_new_write(AspeedI2CBus *bus, hwaddr offset,
                                     uint64_t value, unsigned size)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    bool handle_rx;
    bool w1t;

    trace_aspeed_i2c_bus_write(bus->id, offset, size, value);

    switch (offset) {
    case A_I2CC_FUN_CTRL:
        bus->regs[R_I2CC_FUN_CTRL] = value;
        break;
    case A_I2CC_AC_TIMING:
        bus->regs[R_I2CC_AC_TIMING] = value & 0x1ffff0ff;
        break;
    case A_I2CC_MS_TXRX_BYTE_BUF:
        SHARED_ARRAY_FIELD_DP32(bus->regs, R_I2CC_MS_TXRX_BYTE_BUF, TX_BUF,
                                value);
        break;
    case A_I2CC_POOL_CTRL:
        bus->regs[R_I2CC_POOL_CTRL] &= ~0xffffff;
        bus->regs[R_I2CC_POOL_CTRL] |= (value & 0xffffff);
        break;
    case A_I2CM_INTR_CTRL:
        bus->regs[R_I2CM_INTR_CTRL] = value & 0x0007f07f;
        break;
    case A_I2CM_INTR_STS:
        handle_rx = SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CM_INTR_STS, RX_DONE)
                    && SHARED_FIELD_EX32(value, RX_DONE);

        /* In packet mode, clearing PKT_CMD_DONE clears other interrupts. */
        if (aspeed_i2c_bus_pkt_mode_en(bus) &&
           FIELD_EX32(value, I2CM_INTR_STS, PKT_CMD_DONE)) {
            bus->regs[R_I2CM_INTR_STS] &= 0xf0001000;
            if (!bus->regs[R_I2CM_INTR_STS]) {
                bus->controller->intr_status &= ~(1 << bus->id);
                qemu_irq_lower(aic->bus_get_irq(bus));
            }
            aspeed_i2c_bus_raise_slave_interrupt(bus);
            break;
        }
        bus->regs[R_I2CM_INTR_STS] &= ~(value & 0xf007f07f);
        if (!bus->regs[R_I2CM_INTR_STS]) {
            bus->controller->intr_status &= ~(1 << bus->id);
            qemu_irq_lower(aic->bus_get_irq(bus));
        }
        if (handle_rx && (SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CM_CMD,
                                                  M_RX_CMD) ||
                          SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CM_CMD,
                                                  M_S_RX_CMD_LAST))) {
            aspeed_i2c_handle_rx_cmd(bus);
            aspeed_i2c_bus_raise_interrupt(bus);
        }
        break;
    case A_I2CM_CMD:
        if (!aspeed_i2c_bus_is_enabled(bus)) {
            break;
        }

        if (!aspeed_i2c_bus_is_master(bus)) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: Master mode is not enabled\n",
                          __func__);
            break;
        }

        if (!aic->has_dma &&
            (SHARED_FIELD_EX32(value, RX_DMA_EN) ||
             SHARED_FIELD_EX32(value, TX_DMA_EN))) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA support\n",  __func__);
            break;
        }

        if (bus->regs[R_I2CM_INTR_STS] & 0xffff0000) {
            qemu_log_mask(LOG_UNIMP, "%s: Packet mode is not implemented\n",
                          __func__);
            break;
        }

        value &= 0xff0ffbfb;
        if (ARRAY_FIELD_EX32(bus->regs, I2CM_CMD, W1_CTRL)) {
            bus->regs[R_I2CM_CMD] |= value;
        } else {
            bus->regs[R_I2CM_CMD] = value;
        }

        aspeed_i2c_bus_handle_cmd(bus, value);
        aspeed_i2c_bus_raise_interrupt(bus);
        break;
    case A_I2CM_DMA_TX_ADDR:
        bus->regs[R_I2CM_DMA_TX_ADDR] = FIELD_EX32(value, I2CM_DMA_TX_ADDR,
                                                   ADDR);
        bus->dma_dram_offset =
            deposit64(bus->dma_dram_offset, 0, 32,
                      FIELD_EX32(value, I2CM_DMA_TX_ADDR, ADDR));
        bus->regs[R_I2CC_DMA_LEN] = ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN,
                                                     TX_BUF_LEN) + 1;
        break;
    case A_I2CM_DMA_RX_ADDR:
        bus->regs[R_I2CM_DMA_RX_ADDR] = FIELD_EX32(value, I2CM_DMA_RX_ADDR,
                                                   ADDR);
        bus->dma_dram_offset =
            deposit64(bus->dma_dram_offset, 0, 32,
                      FIELD_EX32(value, I2CM_DMA_RX_ADDR, ADDR));
        bus->regs[R_I2CC_DMA_LEN] = ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN,
                                                     RX_BUF_LEN) + 1;
        break;
    case A_I2CM_DMA_LEN:
        w1t = FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN_W1T) ||
              FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN_W1T);
        /* If none of the w1t bits are set, just write to the reg as normal. */
        if (!w1t) {
            bus->regs[R_I2CM_DMA_LEN] = value;
            break;
        }
        if (FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN_W1T)) {
            ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN, RX_BUF_LEN,
                             FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN));
        }
        if (FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN_W1T)) {
            ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN, TX_BUF_LEN,
                             FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN));
        }
        break;
    case A_I2CM_DMA_LEN_STS:
        /* Writes clear to 0 */
        bus->regs[R_I2CM_DMA_LEN_STS] = 0;
        break;
    case A_I2CC_DMA_ADDR:
    case A_I2CC_DMA_LEN:
        /* RO */
        break;
    case A_I2CS_DEV_ADDR:
        bus->regs[R_I2CS_DEV_ADDR] = value;
        break;
    case A_I2CS_DMA_RX_ADDR:
        bus->regs[R_I2CS_DMA_RX_ADDR] = value;
        break;
    case A_I2CS_DMA_LEN:
        assert(FIELD_EX32(value, I2CS_DMA_LEN, TX_BUF_LEN) == 0);
        if (FIELD_EX32(value, I2CS_DMA_LEN, RX_BUF_LEN_W1T)) {
            ARRAY_FIELD_DP32(bus->regs, I2CS_DMA_LEN, RX_BUF_LEN,
                             FIELD_EX32(value, I2CS_DMA_LEN, RX_BUF_LEN));
        } else {
            bus->regs[R_I2CS_DMA_LEN] = value;
        }
        break;
    case A_I2CS_CMD:
        if (FIELD_EX32(value, I2CS_CMD, W1_CTRL)) {
            bus->regs[R_I2CS_CMD] |= value;
        } else {
            bus->regs[R_I2CS_CMD] = value;
        }
        i2c_slave_set_address(bus->slave, bus->regs[R_I2CS_DEV_ADDR]);
        break;
    case A_I2CS_INTR_CTRL:
        bus->regs[R_I2CS_INTR_CTRL] = value;
        break;

    case A_I2CS_INTR_STS:
        if (ARRAY_FIELD_EX32(bus->regs, I2CS_INTR_CTRL, PKT_CMD_DONE)) {
            if (ARRAY_FIELD_EX32(bus->regs, I2CS_INTR_STS, PKT_CMD_DONE) &&
                FIELD_EX32(value, I2CS_INTR_STS, PKT_CMD_DONE)) {
                bus->regs[R_I2CS_INTR_STS] &= 0xfffc0000;
            }
        } else {
            bus->regs[R_I2CS_INTR_STS] &= ~value;
        }
        if (!bus->regs[R_I2CS_INTR_STS]) {
            bus->controller->intr_status &= ~(1 << bus->id);
            qemu_irq_lower(aic->bus_get_irq(bus));
        }
        aspeed_i2c_bus_raise_interrupt(bus);
        break;
    case A_I2CS_DMA_LEN_STS:
        bus->regs[R_I2CS_DMA_LEN_STS] = 0;
        break;
    case A_I2CS_DMA_TX_ADDR:
        qemu_log_mask(LOG_UNIMP, "%s: Slave mode DMA TX is not implemented\n",
                      __func__);
        break;

    /*
     * The AST2700 support the maximum DRAM size is 8 GB.
     * The DRAM offset range is from 0x0_0000_0000 to
     * 0x1_FFFF_FFFF and it is enough to use bits [33:0]
     * saving the dram offset.
     * Therefore, save the high part physical address bit[1:0]
     * of Tx/Rx buffer address as dma_dram_offset bit[33:32].
     */
    case A_I2CM_DMA_TX_ADDR_HI:
        if (!aic->has_dma64) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA 64 bits support\n",
                          __func__);
            break;
        }
        bus->regs[R_I2CM_DMA_TX_ADDR_HI] = FIELD_EX32(value,
                                                      I2CM_DMA_TX_ADDR_HI,
                                                      ADDR_HI);
        bus->dma_dram_offset = deposit64(bus->dma_dram_offset, 32, 32,
                                         extract32(value, 0, 2));
        break;
    case A_I2CM_DMA_RX_ADDR_HI:
        if (!aic->has_dma64) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA 64 bits support\n",
                          __func__);
            break;
        }
        bus->regs[R_I2CM_DMA_RX_ADDR_HI] = FIELD_EX32(value,
                                                      I2CM_DMA_RX_ADDR_HI,
                                                      ADDR_HI);
        bus->dma_dram_offset = deposit64(bus->dma_dram_offset, 32, 32,
                                         extract32(value, 0, 2));
        break;
    case A_I2CS_DMA_TX_ADDR_HI:
        qemu_log_mask(LOG_UNIMP,
                      "%s: Slave mode DMA TX Addr high is not implemented\n",
                      __func__);
        break;
    case A_I2CS_DMA_RX_ADDR_HI:
        if (!aic->has_dma64) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA 64 bits support\n",
                          __func__);
            break;
        }
        bus->regs[R_I2CS_DMA_RX_ADDR_HI] = FIELD_EX32(value,
                                                      I2CS_DMA_RX_ADDR_HI,
                                                      ADDR_HI);
        bus->dma_dram_offset = deposit64(bus->dma_dram_offset, 32, 32,
                                         extract32(value, 0, 2));
        break;
    default:
        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
                      __func__, offset);
    }
}

static void aspeed_i2c_bus_old_write(AspeedI2CBus *bus, hwaddr offset,
                                     uint64_t value, unsigned size)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(bus->controller);
    bool handle_rx;

    trace_aspeed_i2c_bus_write(bus->id, offset, size, value);

    switch (offset) {
    case A_I2CD_FUN_CTRL:
        if (SHARED_FIELD_EX32(value, SLAVE_EN)) {
            i2c_slave_set_address(bus->slave, bus->regs[R_I2CD_DEV_ADDR]);
        }
        bus->regs[R_I2CD_FUN_CTRL] = value & 0x0071C3FF;
        break;
    case A_I2CD_AC_TIMING1:
        bus->regs[R_I2CD_AC_TIMING1] = value & 0xFFFFF0F;
        break;
    case A_I2CD_AC_TIMING2:
        bus->regs[R_I2CD_AC_TIMING2] = value & 0x7;
        break;
    case A_I2CD_INTR_CTRL:
        bus->regs[R_I2CD_INTR_CTRL] = value & 0x7FFF;
        break;
    case A_I2CD_INTR_STS:
        handle_rx = SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CD_INTR_STS, RX_DONE)
                    && SHARED_FIELD_EX32(value, RX_DONE);
        bus->regs[R_I2CD_INTR_STS] &= ~(value & 0x7FFF);
        if (!bus->regs[R_I2CD_INTR_STS]) {
            bus->controller->intr_status &= ~(1 << bus->id);
            qemu_irq_lower(aic->bus_get_irq(bus));
        }
        if (handle_rx) {
            if (SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CD_CMD, M_RX_CMD) ||
                SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CD_CMD,
                                        M_S_RX_CMD_LAST)) {
                aspeed_i2c_handle_rx_cmd(bus);
                aspeed_i2c_bus_raise_interrupt(bus);
            } else if (aspeed_i2c_get_state(bus) == I2CD_STXD) {
                i2c_ack(bus->bus);
            }
        }
        break;
    case A_I2CD_DEV_ADDR:
        bus->regs[R_I2CD_DEV_ADDR] = value;
        break;
    case A_I2CD_POOL_CTRL:
        bus->regs[R_I2CD_POOL_CTRL] &= ~0xffffff;
        bus->regs[R_I2CD_POOL_CTRL] |= (value & 0xffffff);
        break;

    case A_I2CD_BYTE_BUF:
        SHARED_ARRAY_FIELD_DP32(bus->regs, R_I2CD_BYTE_BUF, TX_BUF, value);
        break;
    case A_I2CD_CMD:
        if (!aspeed_i2c_bus_is_enabled(bus)) {
            break;
        }

        if (!aspeed_i2c_bus_is_master(bus)) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: Master mode is not enabled\n",
                          __func__);
            break;
        }

        if (!aic->has_dma &&
            (SHARED_FIELD_EX32(value, RX_DMA_EN) ||
             SHARED_FIELD_EX32(value, TX_DMA_EN))) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA support\n",  __func__);
            break;
        }

        bus->regs[R_I2CD_CMD] &= ~0xFFFF;
        bus->regs[R_I2CD_CMD] |= value & 0xFFFF;

        aspeed_i2c_bus_handle_cmd(bus, value);
        aspeed_i2c_bus_raise_interrupt(bus);
        break;
    case A_I2CD_DMA_ADDR:
        if (!aic->has_dma) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA support\n",  __func__);
            break;
        }

        bus->dma_dram_offset = deposit64(bus->dma_dram_offset, 0, 32,
                                         value & 0x3ffffffc);
        break;

    case A_I2CD_DMA_LEN:
        if (!aic->has_dma) {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: No DMA support\n",  __func__);
            break;
        }

        bus->regs[R_I2CD_DMA_LEN] = value & 0xfff;
        if (!bus->regs[R_I2CD_DMA_LEN]) {
            qemu_log_mask(LOG_UNIMP, "%s: invalid DMA length\n",  __func__);
        }
        break;

    default:
        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
                      __func__, offset);
    }
}

static void aspeed_i2c_bus_write(void *opaque, hwaddr offset,
                                     uint64_t value, unsigned size)
{
    AspeedI2CBus *bus = opaque;
    if (aspeed_i2c_is_new_mode(bus->controller)) {
        aspeed_i2c_bus_new_write(bus, offset, value, size);
    } else {
        aspeed_i2c_bus_old_write(bus, offset, value, size);
    }
}

static uint64_t aspeed_i2c_ctrl_read(void *opaque, hwaddr offset,
                                   unsigned size)
{
    AspeedI2CState *s = opaque;

    switch (offset) {
    case A_I2C_CTRL_STATUS:
        return s->intr_status;
    case A_I2C_CTRL_GLOBAL:
        return s->ctrl_global;
    case A_I2C_CTRL_NEW_CLK_DIVIDER:
        if (aspeed_i2c_is_new_mode(s)) {
            return s->new_clk_divider;
        }
        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
                      __func__, offset);
        break;
    default:
        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
                      __func__, offset);
        break;
    }

    return -1;
}

static void aspeed_i2c_ctrl_write(void *opaque, hwaddr offset,
                                  uint64_t value, unsigned size)
{
    AspeedI2CState *s = opaque;

    switch (offset) {
    case A_I2C_CTRL_GLOBAL:
        s->ctrl_global = value;
        break;
    case A_I2C_CTRL_NEW_CLK_DIVIDER:
        if (aspeed_i2c_is_new_mode(s)) {
            s->new_clk_divider = value;
        } else {
            qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx
                          "\n", __func__, offset);
        }
        break;
    case A_I2C_CTRL_STATUS:
    default:
        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
                      __func__, offset);
        break;
    }
}

static const MemoryRegionOps aspeed_i2c_bus_ops = {
    .read = aspeed_i2c_bus_read,
    .write = aspeed_i2c_bus_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
};

static const MemoryRegionOps aspeed_i2c_ctrl_ops = {
    .read = aspeed_i2c_ctrl_read,
    .write = aspeed_i2c_ctrl_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
};

static uint64_t aspeed_i2c_share_pool_read(void *opaque, hwaddr offset,
                                     unsigned size)
{
    AspeedI2CState *s = opaque;
    uint64_t ret = 0;
    int i;

    for (i = 0; i < size; i++) {
        ret |= (uint64_t) s->share_pool[offset + i] << (8 * i);
    }

    return ret;
}

static void aspeed_i2c_share_pool_write(void *opaque, hwaddr offset,
                                  uint64_t value, unsigned size)
{
    AspeedI2CState *s = opaque;
    int i;

    for (i = 0; i < size; i++) {
        s->share_pool[offset + i] = (value >> (8 * i)) & 0xFF;
    }
}

static const MemoryRegionOps aspeed_i2c_share_pool_ops = {
    .read = aspeed_i2c_share_pool_read,
    .write = aspeed_i2c_share_pool_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
    .valid = {
        .min_access_size = 1,
        .max_access_size = 4,
    },
};

static uint64_t aspeed_i2c_bus_pool_read(void *opaque, hwaddr offset,
                                     unsigned size)
{
    AspeedI2CBus *s = opaque;
    uint64_t ret = 0;
    int i;

    for (i = 0; i < size; i++) {
        ret |= (uint64_t) s->pool[offset + i] << (8 * i);
    }

    return ret;
}

static void aspeed_i2c_bus_pool_write(void *opaque, hwaddr offset,
                                  uint64_t value, unsigned size)
{
    AspeedI2CBus *s = opaque;
    int i;

    for (i = 0; i < size; i++) {
        s->pool[offset + i] = (value >> (8 * i)) & 0xFF;
    }
}

static const MemoryRegionOps aspeed_i2c_bus_pool_ops = {
    .read = aspeed_i2c_bus_pool_read,
    .write = aspeed_i2c_bus_pool_write,
    .endianness = DEVICE_LITTLE_ENDIAN,
    .valid = {
        .min_access_size = 1,
        .max_access_size = 4,
    },
};

static const VMStateDescription aspeed_i2c_bus_vmstate = {
    .name = TYPE_ASPEED_I2C,
    .version_id = 6,
    .minimum_version_id = 6,
    .fields = (const VMStateField[]) {
        VMSTATE_UINT32_ARRAY(regs, AspeedI2CBus, ASPEED_I2C_NEW_NUM_REG),
        VMSTATE_UINT8_ARRAY(pool, AspeedI2CBus, ASPEED_I2C_BUS_POOL_SIZE),
        VMSTATE_UINT64(dma_dram_offset, AspeedI2CBus),
        VMSTATE_END_OF_LIST()
    }
};

static const VMStateDescription aspeed_i2c_vmstate = {
    .name = TYPE_ASPEED_I2C,
    .version_id = 3,
    .minimum_version_id = 3,
    .fields = (const VMStateField[]) {
        VMSTATE_UINT32(intr_status, AspeedI2CState),
        VMSTATE_STRUCT_ARRAY(busses, AspeedI2CState,
                             ASPEED_I2C_NR_BUSSES, 1, aspeed_i2c_bus_vmstate,
                             AspeedI2CBus),
        VMSTATE_UINT8_ARRAY(share_pool, AspeedI2CState,
                            ASPEED_I2C_SHARE_POOL_SIZE),
        VMSTATE_END_OF_LIST()
    }
};

static void aspeed_i2c_reset(DeviceState *dev)
{
    AspeedI2CState *s = ASPEED_I2C(dev);

    s->intr_status = 0;
}

static void aspeed_i2c_instance_init(Object *obj)
{
    AspeedI2CState *s = ASPEED_I2C(obj);
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(s);
    int i;

    for (i = 0; i < aic->num_busses; i++) {
        object_initialize_child(obj, "bus[*]", &s->busses[i],
                                TYPE_ASPEED_I2C_BUS);
    }
}

/*
 * Address Definitions (AST2400 and AST2500)
 *
 *   0x000 ... 0x03F: Global Register
 *   0x040 ... 0x07F: Device 1
 *   0x080 ... 0x0BF: Device 2
 *   0x0C0 ... 0x0FF: Device 3
 *   0x100 ... 0x13F: Device 4
 *   0x140 ... 0x17F: Device 5
 *   0x180 ... 0x1BF: Device 6
 *   0x1C0 ... 0x1FF: Device 7
 *   0x200 ... 0x20F: Device 1 buffer (AST2500 unused in linux driver)
 *   0x210 ... 0x21F: Device 2 buffer
 *   0x220 ... 0x22F: Device 3 buffer
 *   0x230 ... 0x23F: Device 4 buffer
 *   0x240 ... 0x24F: Device 5 buffer
 *   0x250 ... 0x25F: Device 6 buffer
 *   0x260 ... 0x26F: Device 7 buffer
 *   0x270 ... 0x27F: Device 8 buffer
 *   0x280 ... 0x28F: Device 9 buffer
 *   0x290 ... 0x29F: Device 10 buffer
 *   0x2A0 ... 0x2AF: Device 11 buffer
 *   0x2B0 ... 0x2BF: Device 12 buffer
 *   0x2C0 ... 0x2CF: Device 13 buffer
 *   0x2D0 ... 0x2DF: Device 14 buffer
 *   0x2E0 ... 0x2FF: Reserved
 *   0x300 ... 0x33F: Device 8
 *   0x340 ... 0x37F: Device 9
 *   0x380 ... 0x3BF: Device 10
 *   0x3C0 ... 0x3FF: Device 11
 *   0x400 ... 0x43F: Device 12
 *   0x440 ... 0x47F: Device 13
 *   0x480 ... 0x4BF: Device 14
 *   0x800 ... 0xFFF: Buffer Pool (AST2400 unused in linux driver)
 *
 * Address Definitions (AST2600 and AST1030)
 *   0x000 ... 0x07F: Global Register
 *   0x080 ... 0x0FF: Device 1
 *   0x100 ... 0x17F: Device 2
 *   0x180 ... 0x1FF: Device 3
 *   0x200 ... 0x27F: Device 4
 *   0x280 ... 0x2FF: Device 5
 *   0x300 ... 0x37F: Device 6
 *   0x380 ... 0x3FF: Device 7
 *   0x400 ... 0x47F: Device 8
 *   0x480 ... 0x4FF: Device 9
 *   0x500 ... 0x57F: Device 10
 *   0x580 ... 0x5FF: Device 11
 *   0x600 ... 0x67F: Device 12
 *   0x680 ... 0x6FF: Device 13
 *   0x700 ... 0x77F: Device 14
 *   0x780 ... 0x7FF: Device 15 (15 and 16 unused in AST1030)
 *   0x800 ... 0x87F: Device 16
 *   0xC00 ... 0xC1F: Device 1 buffer
 *   0xC20 ... 0xC3F: Device 2 buffer
 *   0xC40 ... 0xC5F: Device 3 buffer
 *   0xC60 ... 0xC7F: Device 4 buffer
 *   0xC80 ... 0xC9F: Device 5 buffer
 *   0xCA0 ... 0xCBF: Device 6 buffer
 *   0xCC0 ... 0xCDF: Device 7 buffer
 *   0xCE0 ... 0xCFF: Device 8 buffer
 *   0xD00 ... 0xD1F: Device 9 buffer
 *   0xD20 ... 0xD3F: Device 10 buffer
 *   0xD40 ... 0xD5F: Device 11 buffer
 *   0xD60 ... 0xD7F: Device 12 buffer
 *   0xD80 ... 0xD9F: Device 13 buffer
 *   0xDA0 ... 0xDBF: Device 14 buffer
 *   0xDC0 ... 0xDDF: Device 15 buffer (15 and 16 unused in AST1030)
 *   0xDE0 ... 0xDFF: Device 16 buffer
 *
 * Address Definitions (AST2700)
 *   0x000 ... 0x0FF: Global Register
 *   0x100 ... 0x17F: Device 0
 *   0x1A0 ... 0x1BF: Device 0 buffer
 *   0x200 ... 0x27F: Device 1
 *   0x2A0 ... 0x2BF: Device 1 buffer
 *   0x300 ... 0x37F: Device 2
 *   0x3A0 ... 0x3BF: Device 2 buffer
 *   0x400 ... 0x47F: Device 3
 *   0x4A0 ... 0x4BF: Device 3 buffer
 *   0x500 ... 0x57F: Device 4
 *   0x5A0 ... 0x5BF: Device 4 buffer
 *   0x600 ... 0x67F: Device 5
 *   0x6A0 ... 0x6BF: Device 5 buffer
 *   0x700 ... 0x77F: Device 6
 *   0x7A0 ... 0x7BF: Device 6 buffer
 *   0x800 ... 0x87F: Device 7
 *   0x8A0 ... 0x8BF: Device 7 buffer
 *   0x900 ... 0x97F: Device 8
 *   0x9A0 ... 0x9BF: Device 8 buffer
 *   0xA00 ... 0xA7F: Device 9
 *   0xAA0 ... 0xABF: Device 9 buffer
 *   0xB00 ... 0xB7F: Device 10
 *   0xBA0 ... 0xBBF: Device 10 buffer
 *   0xC00 ... 0xC7F: Device 11
 *   0xCA0 ... 0xCBF: Device 11 buffer
 *   0xD00 ... 0xD7F: Device 12
 *   0xDA0 ... 0xDBF: Device 12 buffer
 *   0xE00 ... 0xE7F: Device 13
 *   0xEA0 ... 0xEBF: Device 13 buffer
 *   0xF00 ... 0xF7F: Device 14
 *   0xFA0 ... 0xFBF: Device 14 buffer
 *   0x1000 ... 0x107F: Device 15
 *   0x10A0 ... 0x10BF: Device 15 buffer
 */
static void aspeed_i2c_realize(DeviceState *dev, Error **errp)
{
    int i;
    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
    AspeedI2CState *s = ASPEED_I2C(dev);
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(s);
    uint32_t reg_offset = aic->reg_size + aic->reg_gap_size;
    uint32_t pool_offset = aic->pool_size + aic->pool_gap_size;

    sysbus_init_irq(sbd, &s->irq);
    memory_region_init_io(&s->iomem, OBJECT(s), &aspeed_i2c_ctrl_ops, s,
                          "aspeed.i2c", aic->mem_size);
    sysbus_init_mmio(sbd, &s->iomem);

    for (i = 0; i < aic->num_busses; i++) {
        Object *bus = OBJECT(&s->busses[i]);
        int offset = i < aic->gap ? 1 : 5;

        if (!object_property_set_link(bus, "controller", OBJECT(s), errp)) {
            return;
        }

        if (!object_property_set_uint(bus, "bus-id", i, errp)) {
            return;
        }

        if (!sysbus_realize(SYS_BUS_DEVICE(bus), errp)) {
            return;
        }

        memory_region_add_subregion(&s->iomem, reg_offset * (i + offset),
                                    &s->busses[i].mr);
    }

    if (aic->has_share_pool) {
        memory_region_init_io(&s->pool_iomem, OBJECT(s),
                              &aspeed_i2c_share_pool_ops, s,
                              "aspeed.i2c-share-pool", aic->pool_size);
        memory_region_add_subregion(&s->iomem, aic->pool_base,
                                    &s->pool_iomem);
    } else {
        for (i = 0; i < aic->num_busses; i++) {
            memory_region_add_subregion(&s->iomem,
                                        aic->pool_base + (pool_offset * i),
                                        &s->busses[i].mr_pool);
        }
    }

    if (aic->has_dma) {
        if (!s->dram_mr) {
            error_setg(errp, TYPE_ASPEED_I2C ": 'dram' link not set");
            return;
        }

        address_space_init(&s->dram_as, s->dram_mr,
                           TYPE_ASPEED_I2C "-dma-dram");
    }
}

static const Property aspeed_i2c_properties[] = {
    DEFINE_PROP_LINK("dram", AspeedI2CState, dram_mr,
                     TYPE_MEMORY_REGION, MemoryRegion *),
};

static void aspeed_i2c_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);

    dc->vmsd = &aspeed_i2c_vmstate;
    device_class_set_legacy_reset(dc, aspeed_i2c_reset);
    device_class_set_props(dc, aspeed_i2c_properties);
    dc->realize = aspeed_i2c_realize;
    dc->desc = "Aspeed I2C Controller";
}

static const TypeInfo aspeed_i2c_info = {
    .name          = TYPE_ASPEED_I2C,
    .parent        = TYPE_SYS_BUS_DEVICE,
    .instance_init = aspeed_i2c_instance_init,
    .instance_size = sizeof(AspeedI2CState),
    .class_init    = aspeed_i2c_class_init,
    .class_size = sizeof(AspeedI2CClass),
    .abstract   = true,
};

static int aspeed_i2c_bus_new_slave_event(AspeedI2CBus *bus,
                                          enum i2c_event event)
{
    switch (event) {
    case I2C_START_SEND_ASYNC:
        if (!SHARED_ARRAY_FIELD_EX32(bus->regs, R_I2CS_CMD, RX_DMA_EN)) {
            qemu_log_mask(LOG_GUEST_ERROR,
                          "%s: Slave mode RX DMA is not enabled\n", __func__);
            return -1;
        }
        ARRAY_FIELD_DP32(bus->regs, I2CS_DMA_LEN_STS, RX_LEN, 0);
        bus->dma_dram_offset =
            deposit64(bus->dma_dram_offset, 0, 32,
                      ARRAY_FIELD_EX32(bus->regs, I2CS_DMA_RX_ADDR, ADDR));
        bus->regs[R_I2CC_DMA_LEN] =
            ARRAY_FIELD_EX32(bus->regs, I2CS_DMA_LEN, RX_BUF_LEN) + 1;
        i2c_ack(bus->bus);
        break;
    case I2C_FINISH:
        ARRAY_FIELD_DP32(bus->regs, I2CS_INTR_STS, PKT_CMD_DONE, 1);
        ARRAY_FIELD_DP32(bus->regs, I2CS_INTR_STS, SLAVE_ADDR_RX_MATCH, 1);
        SHARED_ARRAY_FIELD_DP32(bus->regs, R_I2CS_INTR_STS, NORMAL_STOP, 1);
        SHARED_ARRAY_FIELD_DP32(bus->regs, R_I2CS_INTR_STS, RX_DONE, 1);
        aspeed_i2c_bus_raise_slave_interrupt(bus);
        break;
    default:
        qemu_log_mask(LOG_UNIMP, "%s: i2c event %d unimplemented\n",
                      __func__, event);
        return -1;
    }

    return 0;
}

static int aspeed_i2c_bus_slave_event(I2CSlave *slave, enum i2c_event event)
{
    BusState *qbus = qdev_get_parent_bus(DEVICE(slave));
    AspeedI2CBus *bus = ASPEED_I2C_BUS(qbus->parent);
    uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
    uint32_t reg_byte_buf = aspeed_i2c_bus_byte_buf_offset(bus);
    uint32_t reg_dev_addr = aspeed_i2c_bus_dev_addr_offset(bus);
    uint32_t dev_addr = SHARED_ARRAY_FIELD_EX32(bus->regs, reg_dev_addr,
                                                SLAVE_DEV_ADDR1);

    if (aspeed_i2c_is_new_mode(bus->controller)) {
        return aspeed_i2c_bus_new_slave_event(bus, event);
    }

    switch (event) {
    case I2C_START_SEND_ASYNC:
        /* Bit[0] == 0 indicates "send". */
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_byte_buf, RX_BUF, dev_addr << 1);

        ARRAY_FIELD_DP32(bus->regs, I2CD_INTR_STS, SLAVE_ADDR_RX_MATCH, 1);
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, RX_DONE, 1);

        aspeed_i2c_set_state(bus, I2CD_STXD);

        break;

    case I2C_FINISH:
        SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, NORMAL_STOP, 1);

        aspeed_i2c_set_state(bus, I2CD_IDLE);

        break;

    default:
        return -1;
    }

    aspeed_i2c_bus_raise_interrupt(bus);

    return 0;
}

static void aspeed_i2c_bus_new_slave_send_async(AspeedI2CBus *bus, uint8_t data)
{
    assert(address_space_write(&bus->controller->dram_as,
                               bus->dma_dram_offset,
                               MEMTXATTRS_UNSPECIFIED, &data, 1) == MEMTX_OK);

    bus->dma_dram_offset++;
    bus->regs[R_I2CC_DMA_LEN]--;
    ARRAY_FIELD_DP32(bus->regs, I2CS_DMA_LEN_STS, RX_LEN,
                     ARRAY_FIELD_EX32(bus->regs, I2CS_DMA_LEN_STS, RX_LEN) + 1);
    i2c_ack(bus->bus);
}

static void aspeed_i2c_bus_slave_send_async(I2CSlave *slave, uint8_t data)
{
    BusState *qbus = qdev_get_parent_bus(DEVICE(slave));
    AspeedI2CBus *bus = ASPEED_I2C_BUS(qbus->parent);
    uint32_t reg_intr_sts = aspeed_i2c_bus_intr_sts_offset(bus);
    uint32_t reg_byte_buf = aspeed_i2c_bus_byte_buf_offset(bus);

    if (aspeed_i2c_is_new_mode(bus->controller)) {
        return aspeed_i2c_bus_new_slave_send_async(bus, data);
    }

    SHARED_ARRAY_FIELD_DP32(bus->regs, reg_byte_buf, RX_BUF, data);
    SHARED_ARRAY_FIELD_DP32(bus->regs, reg_intr_sts, RX_DONE, 1);

    aspeed_i2c_bus_raise_interrupt(bus);
}

static void aspeed_i2c_bus_slave_class_init(ObjectClass *klass,
                                            const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);

    dc->desc = "Aspeed I2C Bus Slave";

    sc->event = aspeed_i2c_bus_slave_event;
    sc->send_async = aspeed_i2c_bus_slave_send_async;
}

static const TypeInfo aspeed_i2c_bus_slave_info = {
    .name           = TYPE_ASPEED_I2C_BUS_SLAVE,
    .parent         = TYPE_I2C_SLAVE,
    .instance_size  = sizeof(AspeedI2CBusSlave),
    .class_init     = aspeed_i2c_bus_slave_class_init,
};

static void aspeed_i2c_bus_reset(DeviceState *dev)
{
    AspeedI2CBus *s = ASPEED_I2C_BUS(dev);

    memset(s->regs, 0, sizeof(s->regs));
    i2c_end_transfer(s->bus);
}

static void aspeed_i2c_bus_realize(DeviceState *dev, Error **errp)
{
    AspeedI2CBus *s = ASPEED_I2C_BUS(dev);
    AspeedI2CClass *aic;
    g_autofree char *name = g_strdup_printf(TYPE_ASPEED_I2C_BUS ".%d", s->id);
    g_autofree char *pool_name = g_strdup_printf("%s.pool", name);

    if (!s->controller) {
        error_setg(errp, TYPE_ASPEED_I2C_BUS ": 'controller' link not set");
        return;
    }

    aic = ASPEED_I2C_GET_CLASS(s->controller);

    sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq);

    s->bus = i2c_init_bus(dev, name);
    s->slave = i2c_slave_create_simple(s->bus, TYPE_ASPEED_I2C_BUS_SLAVE,
                                       0xff);

    memory_region_init_io(&s->mr, OBJECT(s), &aspeed_i2c_bus_ops,
                          s, name, aic->reg_size);
    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mr);

    memory_region_init_io(&s->mr_pool, OBJECT(s), &aspeed_i2c_bus_pool_ops,
                          s, pool_name, aic->pool_size);
    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mr_pool);
}

static const Property aspeed_i2c_bus_properties[] = {
    DEFINE_PROP_UINT8("bus-id", AspeedI2CBus, id, 0),
    DEFINE_PROP_LINK("controller", AspeedI2CBus, controller, TYPE_ASPEED_I2C,
                     AspeedI2CState *),
};

static void aspeed_i2c_bus_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);

    dc->desc = "Aspeed I2C Bus";
    dc->realize = aspeed_i2c_bus_realize;
    device_class_set_legacy_reset(dc, aspeed_i2c_bus_reset);
    device_class_set_props(dc, aspeed_i2c_bus_properties);
}

static const TypeInfo aspeed_i2c_bus_info = {
    .name           = TYPE_ASPEED_I2C_BUS,
    .parent         = TYPE_SYS_BUS_DEVICE,
    .instance_size  = sizeof(AspeedI2CBus),
    .class_init     = aspeed_i2c_bus_class_init,
};

static qemu_irq aspeed_2400_i2c_bus_get_irq(AspeedI2CBus *bus)
{
    return bus->controller->irq;
}

static uint8_t *aspeed_2400_i2c_bus_pool_base(AspeedI2CBus *bus)
{
    uint8_t *pool_page =
        &bus->controller->share_pool[ARRAY_FIELD_EX32(bus->regs,
                                                      I2CD_FUN_CTRL,
                                                      POOL_PAGE_SEL) * 0x100];

    return &pool_page[ARRAY_FIELD_EX32(bus->regs, I2CD_POOL_CTRL, OFFSET)];
}

static void aspeed_2400_i2c_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    AspeedI2CClass *aic = ASPEED_I2C_CLASS(klass);

    dc->desc = "ASPEED 2400 I2C Controller";

    aic->num_busses = 14;
    aic->reg_size = 0x40;
    aic->gap = 7;
    aic->bus_get_irq = aspeed_2400_i2c_bus_get_irq;
    aic->has_share_pool = true;
    aic->pool_size = 0x800;
    aic->pool_base = 0x800;
    aic->bus_pool_base = aspeed_2400_i2c_bus_pool_base;
    aic->mem_size = 0x1000;
}

static const TypeInfo aspeed_2400_i2c_info = {
    .name = TYPE_ASPEED_2400_I2C,
    .parent = TYPE_ASPEED_I2C,
    .class_init = aspeed_2400_i2c_class_init,
};

static qemu_irq aspeed_2500_i2c_bus_get_irq(AspeedI2CBus *bus)
{
    return bus->controller->irq;
}

static uint8_t *aspeed_2500_i2c_bus_pool_base(AspeedI2CBus *bus)
{
    return bus->pool;
}

static void aspeed_2500_i2c_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    AspeedI2CClass *aic = ASPEED_I2C_CLASS(klass);

    dc->desc = "ASPEED 2500 I2C Controller";

    aic->num_busses = 14;
    aic->reg_size = 0x40;
    aic->gap = 7;
    aic->bus_get_irq = aspeed_2500_i2c_bus_get_irq;
    aic->pool_size = 0x10;
    aic->pool_base = 0x200;
    aic->bus_pool_base = aspeed_2500_i2c_bus_pool_base;
    aic->check_sram = true;
    aic->has_dma = true;
    aic->mem_size = 0x1000;
}

static const TypeInfo aspeed_2500_i2c_info = {
    .name = TYPE_ASPEED_2500_I2C,
    .parent = TYPE_ASPEED_I2C,
    .class_init = aspeed_2500_i2c_class_init,
};

static qemu_irq aspeed_2600_i2c_bus_get_irq(AspeedI2CBus *bus)
{
    return bus->irq;
}

static void aspeed_2600_i2c_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    AspeedI2CClass *aic = ASPEED_I2C_CLASS(klass);

    dc->desc = "ASPEED 2600 I2C Controller";

    aic->num_busses = 16;
    aic->reg_size = 0x80;
    aic->gap = -1; /* no gap */
    aic->bus_get_irq = aspeed_2600_i2c_bus_get_irq;
    aic->pool_size = 0x20;
    aic->pool_base = 0xC00;
    aic->bus_pool_base = aspeed_2500_i2c_bus_pool_base;
    aic->has_dma = true;
    aic->mem_size = 0x1000;
}

static const TypeInfo aspeed_2600_i2c_info = {
    .name = TYPE_ASPEED_2600_I2C,
    .parent = TYPE_ASPEED_I2C,
    .class_init = aspeed_2600_i2c_class_init,
};

static void aspeed_1030_i2c_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    AspeedI2CClass *aic = ASPEED_I2C_CLASS(klass);

    dc->desc = "ASPEED 1030 I2C Controller";

    aic->num_busses = 14;
    aic->reg_size = 0x80;
    aic->gap = -1; /* no gap */
    aic->bus_get_irq = aspeed_2600_i2c_bus_get_irq;
    aic->pool_size = 0x20;
    aic->pool_base = 0xC00;
    aic->bus_pool_base = aspeed_2500_i2c_bus_pool_base;
    aic->has_dma = true;
    aic->mem_size = 0x10000;
}

static const TypeInfo aspeed_1030_i2c_info = {
    .name = TYPE_ASPEED_1030_I2C,
    .parent = TYPE_ASPEED_I2C,
    .class_init = aspeed_1030_i2c_class_init,
};

static void aspeed_2700_i2c_class_init(ObjectClass *klass, const void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    AspeedI2CClass *aic = ASPEED_I2C_CLASS(klass);

    dc->desc = "ASPEED 2700 I2C Controller";

    aic->num_busses = 16;
    aic->reg_size = 0x80;
    aic->reg_gap_size = 0x80;
    aic->gap = -1; /* no gap */
    aic->bus_get_irq = aspeed_2600_i2c_bus_get_irq;
    aic->pool_size = 0x20;
    aic->pool_gap_size = 0xe0;
    aic->pool_base = 0x1a0;
    aic->bus_pool_base = aspeed_2500_i2c_bus_pool_base;
    aic->has_dma = true;
    aic->mem_size = 0x2000;
    aic->has_dma64 = true;
}

static const TypeInfo aspeed_2700_i2c_info = {
    .name = TYPE_ASPEED_2700_I2C,
    .parent = TYPE_ASPEED_I2C,
    .class_init = aspeed_2700_i2c_class_init,
};

static void aspeed_i2c_register_types(void)
{
    type_register_static(&aspeed_i2c_bus_info);
    type_register_static(&aspeed_i2c_bus_slave_info);
    type_register_static(&aspeed_i2c_info);
    type_register_static(&aspeed_2400_i2c_info);
    type_register_static(&aspeed_2500_i2c_info);
    type_register_static(&aspeed_2600_i2c_info);
    type_register_static(&aspeed_1030_i2c_info);
    type_register_static(&aspeed_2700_i2c_info);
}

type_init(aspeed_i2c_register_types)


I2CBus *aspeed_i2c_get_bus(AspeedI2CState *s, int busnr)
{
    AspeedI2CClass *aic = ASPEED_I2C_GET_CLASS(s);
    I2CBus *bus = NULL;

    if (busnr >= 0 && busnr < aic->num_busses) {
        bus = s->busses[busnr].bus;
    }

    return bus;
}