[Qemu-devel] [PULL 10/28] i2c: add aspeed i2c controller

[Peter Maydell <peter.maydell@linaro.org>]

From: Cédric Le Goater <clg@kaod.org>

The Aspeed AST2400 integrates a set of 14 I2C/SMBus bus controllers
directly connected to the APB bus. They can be programmed as master or
slave but the propopsed model only supports the master mode.

On the TODO list, we also have :

 - improve and harden the state machine.
 - bus recovery support (used by the Linux driver).
 - transfer mode state machine bits. this is not strictly necessary as
   it is mostly used for debug. The bus busy bit is deducted from the
   I2C core engine of qemu.
 - support of the pool buffer: 2048 bytes of internal SRAM (not used
   by the Linux driver).

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Message-id: 1464704307-25178-1-git-send-email-clg@kaod.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm/ast2400.c            |  16 ++
 hw/i2c/Makefile.objs        |   1 +
 hw/i2c/aspeed_i2c.c         | 450 ++++++++++++++++++++++++++++++++++++++++++++
 include/hw/arm/ast2400.h    |   2 +
 include/hw/i2c/aspeed_i2c.h |  62 ++++++
 5 files changed, 531 insertions(+)
 create mode 100644 hw/i2c/aspeed_i2c.c
 create mode 100644 include/hw/i2c/aspeed_i2c.h

diff --git a/hw/arm/ast2400.c b/hw/arm/ast2400.c
index 5510a8a..4a9de0e 100644
--- a/hw/arm/ast2400.c
+++ b/hw/arm/ast2400.c
@@ -18,12 +18,14 @@
 #include "hw/arm/ast2400.h"
 #include "hw/char/serial.h"
 #include "qemu/log.h"
+#include "hw/i2c/aspeed_i2c.h"
 
 #define AST2400_UART_5_BASE      0x00184000
 #define AST2400_IOMEM_SIZE       0x00200000
 #define AST2400_IOMEM_BASE       0x1E600000
 #define AST2400_VIC_BASE         0x1E6C0000
 #define AST2400_TIMER_BASE       0x1E782000
+#define AST2400_I2C_BASE         0x1E78A000
 
 static const int uart_irqs[] = { 9, 32, 33, 34, 10 };
 static const int timer_irqs[] = { 16, 17, 18, 35, 36, 37, 38, 39, };
@@ -66,6 +68,10 @@ static void ast2400_init(Object *obj)
     object_initialize(&s->timerctrl, sizeof(s->timerctrl), TYPE_ASPEED_TIMER);
     object_property_add_child(obj, "timerctrl", OBJECT(&s->timerctrl), NULL);
     qdev_set_parent_bus(DEVICE(&s->timerctrl), sysbus_get_default());
+
+    object_initialize(&s->i2c, sizeof(s->i2c), TYPE_ASPEED_I2C);
+    object_property_add_child(obj, "i2c", OBJECT(&s->i2c), NULL);
+    qdev_set_parent_bus(DEVICE(&s->i2c), sysbus_get_default());
 }
 
 static void ast2400_realize(DeviceState *dev, Error **errp)
@@ -110,6 +116,16 @@ static void ast2400_realize(DeviceState *dev, Error **errp)
         serial_mm_init(&s->iomem, AST2400_UART_5_BASE, 2,
                        uart5, 38400, serial_hds[0], DEVICE_LITTLE_ENDIAN);
     }
+
+    /* I2C */
+    object_property_set_bool(OBJECT(&s->i2c), true, "realized", &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+    sysbus_mmio_map(SYS_BUS_DEVICE(&s->i2c), 0, AST2400_I2C_BASE);
+    sysbus_connect_irq(SYS_BUS_DEVICE(&s->i2c), 0,
+                       qdev_get_gpio_in(DEVICE(&s->vic), 12));
 }
 
 static void ast2400_class_init(ObjectClass *oc, void *data)
diff --git a/hw/i2c/Makefile.objs b/hw/i2c/Makefile.objs
index aeb8f38..1fd54ed 100644
--- a/hw/i2c/Makefile.objs
+++ b/hw/i2c/Makefile.objs
@@ -5,4 +5,5 @@ common-obj-$(CONFIG_APM) += pm_smbus.o
 common-obj-$(CONFIG_BITBANG_I2C) += bitbang_i2c.o
 common-obj-$(CONFIG_EXYNOS4) += exynos4210_i2c.o
 common-obj-$(CONFIG_IMX_I2C) += imx_i2c.o
+common-obj-$(CONFIG_ASPEED_SOC) += aspeed_i2c.o
 obj-$(CONFIG_OMAP) += omap_i2c.o
diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
new file mode 100644
index 0000000..457af1a
--- /dev/null
+++ b/hw/i2c/aspeed_i2c.c
@@ -0,0 +1,450 @@
+/*
+ * 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 "qemu/log.h"
+#include "hw/i2c/aspeed_i2c.h"
+
+/* I2C Global Register */
+
+#define I2C_CTRL_STATUS         0x00        /* Device Interrupt Status */
+#define I2C_CTRL_ASSIGN         0x08        /* Device Interrupt Target
+                                               Assignment */
+
+/* I2C Device (Bus) Register */
+
+#define I2CD_FUN_CTRL_REG       0x00       /* I2CD Function Control  */
+#define   I2CD_BUFF_SEL_MASK               (0x7 << 20)
+#define   I2CD_BUFF_SEL(x)                 (x << 20)
+#define   I2CD_M_SDA_LOCK_EN               (0x1 << 16)
+#define   I2CD_MULTI_MASTER_DIS            (0x1 << 15)
+#define   I2CD_M_SCL_DRIVE_EN              (0x1 << 14)
+#define   I2CD_MSB_STS                     (0x1 << 9)
+#define   I2CD_SDA_DRIVE_1T_EN             (0x1 << 8)
+#define   I2CD_M_SDA_DRIVE_1T_EN           (0x1 << 7)
+#define   I2CD_M_HIGH_SPEED_EN             (0x1 << 6)
+#define   I2CD_DEF_ADDR_EN                 (0x1 << 5)
+#define   I2CD_DEF_ALERT_EN                (0x1 << 4)
+#define   I2CD_DEF_ARP_EN                  (0x1 << 3)
+#define   I2CD_DEF_GCALL_EN                (0x1 << 2)
+#define   I2CD_SLAVE_EN                    (0x1 << 1)
+#define   I2CD_MASTER_EN                   (0x1)
+
+#define I2CD_AC_TIMING_REG1     0x04       /* Clock and AC Timing Control #1 */
+#define I2CD_AC_TIMING_REG2     0x08       /* Clock and AC Timing Control #1 */
+#define I2CD_INTR_CTRL_REG      0x0c       /* I2CD Interrupt Control */
+#define I2CD_INTR_STS_REG       0x10       /* I2CD Interrupt Status */
+#define   I2CD_INTR_SDA_DL_TIMEOUT         (0x1 << 14)
+#define   I2CD_INTR_BUS_RECOVER_DONE       (0x1 << 13)
+#define   I2CD_INTR_SMBUS_ALERT            (0x1 << 12) /* Bus [0-3] only */
+#define   I2CD_INTR_SMBUS_ARP_ADDR         (0x1 << 11) /* Removed */
+#define   I2CD_INTR_SMBUS_DEV_ALERT_ADDR   (0x1 << 10) /* Removed */
+#define   I2CD_INTR_SMBUS_DEF_ADDR         (0x1 << 9)  /* Removed */
+#define   I2CD_INTR_GCALL_ADDR             (0x1 << 8)  /* Removed */
+#define   I2CD_INTR_SLAVE_MATCH            (0x1 << 7)  /* use RX_DONE */
+#define   I2CD_INTR_SCL_TIMEOUT            (0x1 << 6)
+#define   I2CD_INTR_ABNORMAL               (0x1 << 5)
+#define   I2CD_INTR_NORMAL_STOP            (0x1 << 4)
+#define   I2CD_INTR_ARBIT_LOSS             (0x1 << 3)
+#define   I2CD_INTR_RX_DONE                (0x1 << 2)
+#define   I2CD_INTR_TX_NAK                 (0x1 << 1)
+#define   I2CD_INTR_TX_ACK                 (0x1 << 0)
+
+#define I2CD_CMD_REG            0x14       /* I2CD Command/Status */
+#define   I2CD_SDA_OE                      (0x1 << 28)
+#define   I2CD_SDA_O                       (0x1 << 27)
+#define   I2CD_SCL_OE                      (0x1 << 26)
+#define   I2CD_SCL_O                       (0x1 << 25)
+#define   I2CD_TX_TIMING                   (0x1 << 24)
+#define   I2CD_TX_STATUS                   (0x1 << 23)
+
+#define   I2CD_TX_STATE_SHIFT              19 /* Tx State Machine */
+#define   I2CD_TX_STATE_MASK                  0xf
+#define     I2CD_IDLE                         0x0
+#define     I2CD_MACTIVE                      0x8
+#define     I2CD_MSTART                       0x9
+#define     I2CD_MSTARTR                      0xa
+#define     I2CD_MSTOP                        0xb
+#define     I2CD_MTXD                         0xc
+#define     I2CD_MRXACK                       0xd
+#define     I2CD_MRXD                         0xe
+#define     I2CD_MTXACK                       0xf
+#define     I2CD_SWAIT                        0x1
+#define     I2CD_SRXD                         0x4
+#define     I2CD_STXACK                       0x5
+#define     I2CD_STXD                         0x6
+#define     I2CD_SRXACK                       0x7
+#define     I2CD_RECOVER                      0x3
+
+#define   I2CD_SCL_LINE_STS                (0x1 << 18)
+#define   I2CD_SDA_LINE_STS                (0x1 << 17)
+#define   I2CD_BUS_BUSY_STS                (0x1 << 16)
+#define   I2CD_SDA_OE_OUT_DIR              (0x1 << 15)
+#define   I2CD_SDA_O_OUT_DIR               (0x1 << 14)
+#define   I2CD_SCL_OE_OUT_DIR              (0x1 << 13)
+#define   I2CD_SCL_O_OUT_DIR               (0x1 << 12)
+#define   I2CD_BUS_RECOVER_CMD_EN          (0x1 << 11)
+#define   I2CD_S_ALT_EN                    (0x1 << 10)
+#define   I2CD_RX_DMA_ENABLE               (0x1 << 9)
+#define   I2CD_TX_DMA_ENABLE               (0x1 << 8)
+
+/* Command Bit */
+#define   I2CD_M_STOP_CMD                  (0x1 << 5)
+#define   I2CD_M_S_RX_CMD_LAST             (0x1 << 4)
+#define   I2CD_M_RX_CMD                    (0x1 << 3)
+#define   I2CD_S_TX_CMD                    (0x1 << 2)
+#define   I2CD_M_TX_CMD                    (0x1 << 1)
+#define   I2CD_M_START_CMD                 (0x1)
+
+#define I2CD_DEV_ADDR_REG       0x18       /* Slave Device Address */
+#define I2CD_BUF_CTRL_REG       0x1c       /* Pool Buffer Control */
+#define I2CD_BYTE_BUF_REG       0x20       /* Transmit/Receive Byte Buffer */
+#define   I2CD_BYTE_BUF_TX_SHIFT           0
+#define   I2CD_BYTE_BUF_TX_MASK            0xff
+#define   I2CD_BYTE_BUF_RX_SHIFT           8
+#define   I2CD_BYTE_BUF_RX_MASK            0xff
+
+
+static inline bool aspeed_i2c_bus_is_master(AspeedI2CBus *bus)
+{
+    return bus->ctrl & I2CD_MASTER_EN;
+}
+
+static inline bool aspeed_i2c_bus_is_enabled(AspeedI2CBus *bus)
+{
+    return bus->ctrl & (I2CD_MASTER_EN | I2CD_SLAVE_EN);
+}
+
+static inline void aspeed_i2c_bus_raise_interrupt(AspeedI2CBus *bus)
+{
+    bus->intr_status &= bus->intr_ctrl;
+    if (bus->intr_status) {
+        bus->controller->intr_status |= 1 << bus->id;
+        qemu_irq_raise(bus->controller->irq);
+    }
+}
+
+static uint64_t aspeed_i2c_bus_read(void *opaque, hwaddr offset,
+                                    unsigned size)
+{
+    AspeedI2CBus *bus = opaque;
+
+    switch (offset) {
+    case I2CD_FUN_CTRL_REG:
+        return bus->ctrl;
+    case I2CD_AC_TIMING_REG1:
+        return bus->timing[0];
+    case I2CD_AC_TIMING_REG2:
+        return bus->timing[1];
+    case I2CD_INTR_CTRL_REG:
+        return bus->intr_ctrl;
+    case I2CD_INTR_STS_REG:
+        return bus->intr_status;
+    case I2CD_BYTE_BUF_REG:
+        return bus->buf;
+    case I2CD_CMD_REG:
+        return bus->cmd | (i2c_bus_busy(bus->bus) << 16);
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, offset);
+        return -1;
+    }
+}
+
+static inline uint64_t aspeed_i2c_bus_get_state(AspeedI2CBus *bus)
+{
+    return bus->cmd >> 19 & 0xF;
+}
+
+static inline void aspeed_i2c_bus_set_state(AspeedI2CBus *bus, uint64_t value)
+{
+    bus->cmd |= (value & 0xF) << 19;
+}
+
+static void aspeed_i2c_bus_handle_cmd(AspeedI2CBus *bus, uint64_t value)
+{
+    bus->cmd |= value & 0xFFFF;
+    bus->intr_status = 0;
+
+    if (bus->cmd & I2CD_M_START_CMD) {
+        if (i2c_start_transfer(bus->bus, extract32(bus->buf, 1, 7),
+                               extract32(bus->buf, 0, 1))) {
+            bus->intr_status |= I2CD_INTR_TX_NAK;
+        } else {
+            bus->intr_status |= I2CD_INTR_TX_ACK;
+        }
+
+    } else if (bus->cmd & I2CD_M_TX_CMD) {
+        if (i2c_send(bus->bus, bus->buf)) {
+            bus->intr_status |= (I2CD_INTR_TX_NAK | I2CD_INTR_ABNORMAL);
+            i2c_end_transfer(bus->bus);
+        } else {
+            bus->intr_status |= I2CD_INTR_TX_ACK;
+        }
+
+    } else if (bus->cmd & I2CD_M_RX_CMD) {
+        int ret = i2c_recv(bus->bus);
+        if (ret < 0) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: read failed\n", __func__);
+            ret = 0xff;
+        } else {
+            bus->intr_status |= I2CD_INTR_RX_DONE;
+        }
+        bus->buf = (ret & I2CD_BYTE_BUF_RX_MASK) << I2CD_BYTE_BUF_RX_SHIFT;
+    }
+
+    if (bus->cmd & (I2CD_M_STOP_CMD | I2CD_M_S_RX_CMD_LAST)) {
+        if (!i2c_bus_busy(bus->bus)) {
+            bus->intr_status |= I2CD_INTR_ABNORMAL;
+        } else {
+            i2c_end_transfer(bus->bus);
+            bus->intr_status |= I2CD_INTR_NORMAL_STOP;
+        }
+    }
+
+    /* command is handled, reset it and check for interrupts  */
+    bus->cmd &= ~0xFFFF;
+    aspeed_i2c_bus_raise_interrupt(bus);
+}
+
+static void aspeed_i2c_bus_write(void *opaque, hwaddr offset,
+                                 uint64_t value, unsigned size)
+{
+    AspeedI2CBus *bus = opaque;
+
+    switch (offset) {
+    case I2CD_FUN_CTRL_REG:
+        if (value & I2CD_SLAVE_EN) {
+            qemu_log_mask(LOG_UNIMP, "%s: slave mode not implemented\n",
+                          __func__);
+            break;
+        }
+        bus->ctrl = value & 0x0071C3FF;
+        break;
+    case I2CD_AC_TIMING_REG1:
+        bus->timing[0] = value & 0xFFFFF0F;
+        break;
+    case I2CD_AC_TIMING_REG2:
+        bus->timing[1] = value & 0x7;
+        break;
+    case I2CD_INTR_CTRL_REG:
+        bus->intr_ctrl = value & 0x7FFF;
+        break;
+    case I2CD_INTR_STS_REG:
+        bus->intr_status &= ~(value & 0x7FFF);
+        bus->controller->intr_status &= ~(1 << bus->id);
+        qemu_irq_lower(bus->controller->irq);
+        break;
+    case I2CD_DEV_ADDR_REG:
+        qemu_log_mask(LOG_UNIMP, "%s: slave mode not implemented\n",
+                      __func__);
+        break;
+    case I2CD_BYTE_BUF_REG:
+        bus->buf = (value & I2CD_BYTE_BUF_TX_MASK) << I2CD_BYTE_BUF_TX_SHIFT;
+        break;
+    case I2CD_CMD_REG:
+        if (!aspeed_i2c_bus_is_enabled(bus)) {
+            break;
+        }
+
+        if (!aspeed_i2c_bus_is_master(bus)) {
+            qemu_log_mask(LOG_UNIMP, "%s: slave mode not implemented\n",
+                          __func__);
+            break;
+        }
+
+        aspeed_i2c_bus_handle_cmd(bus, value);
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
+                      __func__, offset);
+    }
+}
+
+static uint64_t aspeed_i2c_ctrl_read(void *opaque, hwaddr offset,
+                                   unsigned size)
+{
+    AspeedI2CState *s = opaque;
+
+    switch (offset) {
+    case I2C_CTRL_STATUS:
+        return s->intr_status;
+    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)
+{
+    switch (offset) {
+    case 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 const VMStateDescription aspeed_i2c_bus_vmstate = {
+    .name = TYPE_ASPEED_I2C,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(id, AspeedI2CBus),
+        VMSTATE_UINT32(ctrl, AspeedI2CBus),
+        VMSTATE_UINT32_ARRAY(timing, AspeedI2CBus, 2),
+        VMSTATE_UINT32(intr_ctrl, AspeedI2CBus),
+        VMSTATE_UINT32(intr_status, AspeedI2CBus),
+        VMSTATE_UINT32(cmd, AspeedI2CBus),
+        VMSTATE_UINT32(buf, AspeedI2CBus),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription aspeed_i2c_vmstate = {
+    .name = TYPE_ASPEED_I2C,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(intr_status, AspeedI2CState),
+        VMSTATE_STRUCT_ARRAY(busses, AspeedI2CState,
+                             ASPEED_I2C_NR_BUSSES, 1, aspeed_i2c_bus_vmstate,
+                             AspeedI2CBus),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void aspeed_i2c_reset(DeviceState *dev)
+{
+    int i;
+    AspeedI2CState *s = ASPEED_I2C(dev);
+
+    s->intr_status = 0;
+
+    for (i = 0; i < ASPEED_I2C_NR_BUSSES; i++) {
+        s->busses[i].intr_ctrl = 0;
+        s->busses[i].intr_status = 0;
+        s->busses[i].cmd = 0;
+        s->busses[i].buf = 0;
+        i2c_end_transfer(s->busses[i].bus);
+    }
+}
+
+/*
+ * Address Definitions
+ *
+ *   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 ... 0x2FF: Buffer Pool  (unused in linux driver)
+ *   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  (unused in linux driver)
+ */
+static void aspeed_i2c_realize(DeviceState *dev, Error **errp)
+{
+    int i;
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    AspeedI2CState *s = ASPEED_I2C(dev);
+
+    sysbus_init_irq(sbd, &s->irq);
+    memory_region_init_io(&s->iomem, OBJECT(s), &aspeed_i2c_ctrl_ops, s,
+                          "aspeed.i2c", 0x1000);
+    sysbus_init_mmio(sbd, &s->iomem);
+
+    for (i = 0; i < ASPEED_I2C_NR_BUSSES; i++) {
+        char name[16];
+        int offset = i < 7 ? 1 : 5;
+        snprintf(name, sizeof(name), "aspeed.i2c.%d", i);
+        s->busses[i].controller = s;
+        s->busses[i].id = i;
+        s->busses[i].bus = i2c_init_bus(dev, name);
+        memory_region_init_io(&s->busses[i].mr, OBJECT(dev),
+                              &aspeed_i2c_bus_ops, &s->busses[i], name, 0x40);
+        memory_region_add_subregion(&s->iomem, 0x40 * (i + offset),
+                                    &s->busses[i].mr);
+    }
+}
+
+static void aspeed_i2c_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->vmsd = &aspeed_i2c_vmstate;
+    dc->reset = aspeed_i2c_reset;
+    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_size = sizeof(AspeedI2CState),
+    .class_init    = aspeed_i2c_class_init,
+};
+
+static void aspeed_i2c_register_types(void)
+{
+    type_register_static(&aspeed_i2c_info);
+}
+
+type_init(aspeed_i2c_register_types)
+
+
+I2CBus *aspeed_i2c_get_bus(DeviceState *dev, int busnr)
+{
+    AspeedI2CState *s = ASPEED_I2C(dev);
+    I2CBus *bus = NULL;
+
+    if (busnr >= 0 && busnr < ASPEED_I2C_NR_BUSSES) {
+        bus = s->busses[busnr].bus;
+    }
+
+    return bus;
+}
diff --git a/include/hw/arm/ast2400.h b/include/hw/arm/ast2400.h
index f16a1ed..c05ed53 100644
--- a/include/hw/arm/ast2400.h
+++ b/include/hw/arm/ast2400.h
@@ -15,6 +15,7 @@
 #include "hw/arm/arm.h"
 #include "hw/intc/aspeed_vic.h"
 #include "hw/timer/aspeed_timer.h"
+#include "hw/i2c/aspeed_i2c.h"
 
 typedef struct AST2400State {
     /*< private >*/
@@ -25,6 +26,7 @@ typedef struct AST2400State {
     MemoryRegion iomem;
     AspeedVICState vic;
     AspeedTimerCtrlState timerctrl;
+    AspeedI2CState i2c;
 } AST2400State;
 
 #define TYPE_AST2400 "ast2400"
diff --git a/include/hw/i2c/aspeed_i2c.h b/include/hw/i2c/aspeed_i2c.h
new file mode 100644
index 0000000..f9020ac
--- /dev/null
+++ b/include/hw/i2c/aspeed_i2c.h
@@ -0,0 +1,62 @@
+/*
+ *  ASPEED AST2400 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, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef ASPEED_I2C_H
+#define ASPEED_I2C_H
+
+#include "hw/i2c/i2c.h"
+
+#define TYPE_ASPEED_I2C "aspeed.i2c"
+#define ASPEED_I2C(obj) \
+    OBJECT_CHECK(AspeedI2CState, (obj), TYPE_ASPEED_I2C)
+
+#define ASPEED_I2C_NR_BUSSES 14
+
+struct AspeedI2CState;
+
+typedef struct AspeedI2CBus {
+    struct AspeedI2CState *controller;
+
+    MemoryRegion mr;
+
+    I2CBus *bus;
+    uint8_t id;
+
+    uint32_t ctrl;
+    uint32_t timing[2];
+    uint32_t intr_ctrl;
+    uint32_t intr_status;
+    uint32_t cmd;
+    uint32_t buf;
+} AspeedI2CBus;
+
+typedef struct AspeedI2CState {
+    SysBusDevice parent_obj;
+
+    MemoryRegion iomem;
+    qemu_irq irq;
+
+    uint32_t intr_status;
+
+    AspeedI2CBus busses[ASPEED_I2C_NR_BUSSES];
+} AspeedI2CState;
+
+I2CBus *aspeed_i2c_get_bus(DeviceState *dev, int busnr);
+
+#endif /* ASPEED_I2C_H */
-- 
1.9.1