[PULL 4/9] ppc/pnv: Add an I2C controller model

Daniel Henrique Barboza posted 9 patches 1 year ago
Maintainers: Paolo Bonzini <pbonzini@redhat.com>, BALATON Zoltan <balaton@eik.bme.hu>, "Cédric Le Goater" <clg@kaod.org>, Nicholas Piggin <npiggin@gmail.com>, "Frédéric Barrat" <fbarrat@linux.ibm.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Cleber Rosa <crosa@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Wainer dos Santos Moschetta <wainersm@redhat.com>, Beraldo Leal <bleal@redhat.com>
There is a newer version of this series
[PULL 4/9] ppc/pnv: Add an I2C controller model
Posted by Daniel Henrique Barboza 1 year ago
From: Cédric Le Goater <clg@kaod.org>

The more recent IBM power processors have an embedded I2C
controller that is accessible by software via the XSCOM
address space.

Each instance of the I2C controller is capable of controlling
multiple I2C buses (one at a time).  Prior to beginning a
transaction on an I2C bus, the bus must be selected by writing
the port number associated with the bus into the PORT_NUM
field of the MODE register.  Once an I2C bus is selected,
the status of the bus can be determined by reading the
Status and Extended Status registers.

I2C bus transactions can be started by writing a command to
the Command register and reading/writing data from/to the
FIFO register.

Not supported :

 . 10 bit I2C addresses
 . Multimaster
 . Slave

Signed-off-by: Cédric Le Goater <clg@kaod.org>
[milesg: Split wiring to powernv9 into its own commit]
[milesg: Added more detail to commit message]
[milesg: Added SPDX Licensed Identifier to new files]
[milesg: updated copyright dates]
[milesg: Added use of g_autofree]
[milesg: Added NULL check after pnv_i2c_get_bus]
Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Acked-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-ID: <20231016222013.3739530-2-milesg@linux.vnet.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/meson.build         |   1 +
 hw/ppc/pnv_i2c.c           | 697 +++++++++++++++++++++++++++++++++++++
 include/hw/ppc/pnv_i2c.h   |  38 ++
 include/hw/ppc/pnv_xscom.h |   3 +
 4 files changed, 739 insertions(+)
 create mode 100644 hw/ppc/pnv_i2c.c
 create mode 100644 include/hw/ppc/pnv_i2c.h

diff --git a/hw/ppc/meson.build b/hw/ppc/meson.build
index 7338f9432a..ea44856d43 100644
--- a/hw/ppc/meson.build
+++ b/hw/ppc/meson.build
@@ -43,6 +43,7 @@ ppc_ss.add(when: 'CONFIG_POWERNV', if_true: files(
   'pnv.c',
   'pnv_xscom.c',
   'pnv_core.c',
+  'pnv_i2c.c',
   'pnv_lpc.c',
   'pnv_psi.c',
   'pnv_occ.c',
diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
new file mode 100644
index 0000000000..f75e59e709
--- /dev/null
+++ b/hw/ppc/pnv_i2c.c
@@ -0,0 +1,697 @@
+/*
+ * QEMU PowerPC PowerNV Processor I2C model
+ *
+ * Copyright (c) 2019-2023, IBM Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/module.h"
+#include "qemu/log.h"
+#include "sysemu/reset.h"
+
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+
+#include "hw/ppc/pnv.h"
+#include "hw/ppc/pnv_chip.h"
+#include "hw/ppc/pnv_i2c.h"
+#include "hw/ppc/pnv_xscom.h"
+#include "hw/ppc/fdt.h"
+
+#include <libfdt.h>
+
+/* I2C FIFO register */
+#define I2C_FIFO_REG                    0x4
+#define I2C_FIFO                        PPC_BITMASK(0, 7)
+
+/* I2C command register */
+#define I2C_CMD_REG                     0x5
+#define I2C_CMD_WITH_START              PPC_BIT(0)
+#define I2C_CMD_WITH_ADDR               PPC_BIT(1)
+#define I2C_CMD_READ_CONT               PPC_BIT(2)
+#define I2C_CMD_WITH_STOP               PPC_BIT(3)
+#define I2C_CMD_INTR_STEERING           PPC_BITMASK(6, 7) /* P9 */
+#define   I2C_CMD_INTR_STEER_HOST       1
+#define   I2C_CMD_INTR_STEER_OCC        2
+#define I2C_CMD_DEV_ADDR                PPC_BITMASK(8, 14)
+#define I2C_CMD_READ_NOT_WRITE          PPC_BIT(15)
+#define I2C_CMD_LEN_BYTES               PPC_BITMASK(16, 31)
+#define I2C_MAX_TFR_LEN                 0xfff0ull
+
+/* I2C mode register */
+#define I2C_MODE_REG                    0x6
+#define I2C_MODE_BIT_RATE_DIV           PPC_BITMASK(0, 15)
+#define I2C_MODE_PORT_NUM               PPC_BITMASK(16, 21)
+#define I2C_MODE_ENHANCED               PPC_BIT(28)
+#define I2C_MODE_DIAGNOSTIC             PPC_BIT(29)
+#define I2C_MODE_PACING_ALLOW           PPC_BIT(30)
+#define I2C_MODE_WRAP                   PPC_BIT(31)
+
+/* I2C watermark register */
+#define I2C_WATERMARK_REG               0x7
+#define I2C_WATERMARK_HIGH              PPC_BITMASK(16, 19)
+#define I2C_WATERMARK_LOW               PPC_BITMASK(24, 27)
+
+/*
+ * I2C interrupt mask and condition registers
+ *
+ * NB: The function of 0x9 and 0xa changes depending on whether you're reading
+ *     or writing to them. When read they return the interrupt condition bits
+ *     and on writes they update the interrupt mask register.
+ *
+ *  The bit definitions are the same for all the interrupt registers.
+ */
+#define I2C_INTR_MASK_REG               0x8
+
+#define I2C_INTR_RAW_COND_REG           0x9 /* read */
+#define I2C_INTR_MASK_OR_REG            0x9 /* write*/
+
+#define I2C_INTR_COND_REG               0xa /* read */
+#define I2C_INTR_MASK_AND_REG           0xa /* write */
+
+#define I2C_INTR_ALL                    PPC_BITMASK(16, 31)
+#define I2C_INTR_INVALID_CMD            PPC_BIT(16)
+#define I2C_INTR_LBUS_PARITY_ERR        PPC_BIT(17)
+#define I2C_INTR_BKEND_OVERRUN_ERR      PPC_BIT(18)
+#define I2C_INTR_BKEND_ACCESS_ERR       PPC_BIT(19)
+#define I2C_INTR_ARBT_LOST_ERR          PPC_BIT(20)
+#define I2C_INTR_NACK_RCVD_ERR          PPC_BIT(21)
+#define I2C_INTR_DATA_REQ               PPC_BIT(22)
+#define I2C_INTR_CMD_COMP               PPC_BIT(23)
+#define I2C_INTR_STOP_ERR               PPC_BIT(24)
+#define I2C_INTR_I2C_BUSY               PPC_BIT(25)
+#define I2C_INTR_NOT_I2C_BUSY           PPC_BIT(26)
+#define I2C_INTR_SCL_EQ_1               PPC_BIT(28)
+#define I2C_INTR_SCL_EQ_0               PPC_BIT(29)
+#define I2C_INTR_SDA_EQ_1               PPC_BIT(30)
+#define I2C_INTR_SDA_EQ_0               PPC_BIT(31)
+
+/* I2C status register */
+#define I2C_RESET_I2C_REG               0xb /* write */
+#define I2C_RESET_ERRORS                0xc
+#define I2C_STAT_REG                    0xb /* read */
+#define I2C_STAT_INVALID_CMD            PPC_BIT(0)
+#define I2C_STAT_LBUS_PARITY_ERR        PPC_BIT(1)
+#define I2C_STAT_BKEND_OVERRUN_ERR      PPC_BIT(2)
+#define I2C_STAT_BKEND_ACCESS_ERR       PPC_BIT(3)
+#define I2C_STAT_ARBT_LOST_ERR          PPC_BIT(4)
+#define I2C_STAT_NACK_RCVD_ERR          PPC_BIT(5)
+#define I2C_STAT_DATA_REQ               PPC_BIT(6)
+#define I2C_STAT_CMD_COMP               PPC_BIT(7)
+#define I2C_STAT_STOP_ERR               PPC_BIT(8)
+#define I2C_STAT_UPPER_THRS             PPC_BITMASK(9, 15)
+#define I2C_STAT_ANY_I2C_INTR           PPC_BIT(16)
+#define I2C_STAT_PORT_HISTORY_BUSY      PPC_BIT(19)
+#define I2C_STAT_SCL_INPUT_LEVEL        PPC_BIT(20)
+#define I2C_STAT_SDA_INPUT_LEVEL        PPC_BIT(21)
+#define I2C_STAT_PORT_BUSY              PPC_BIT(22)
+#define I2C_STAT_INTERFACE_BUSY         PPC_BIT(23)
+#define I2C_STAT_FIFO_ENTRY_COUNT       PPC_BITMASK(24, 31)
+
+#define I2C_STAT_ANY_ERR (I2C_STAT_INVALID_CMD | I2C_STAT_LBUS_PARITY_ERR | \
+                          I2C_STAT_BKEND_OVERRUN_ERR | \
+                          I2C_STAT_BKEND_ACCESS_ERR | I2C_STAT_ARBT_LOST_ERR | \
+                          I2C_STAT_NACK_RCVD_ERR | I2C_STAT_STOP_ERR)
+
+
+#define I2C_INTR_ACTIVE \
+        ((I2C_STAT_ANY_ERR >> 16) | I2C_INTR_CMD_COMP | I2C_INTR_DATA_REQ)
+
+/* Pseudo-status used for timeouts */
+#define I2C_STAT_PSEUDO_TIMEOUT         PPC_BIT(63)
+
+/* I2C extended status register */
+#define I2C_EXTD_STAT_REG               0xc
+#define I2C_EXTD_STAT_FIFO_SIZE         PPC_BITMASK(0, 7)
+#define I2C_EXTD_STAT_MSM_CURSTATE      PPC_BITMASK(11, 15)
+#define I2C_EXTD_STAT_SCL_IN_SYNC       PPC_BIT(16)
+#define I2C_EXTD_STAT_SDA_IN_SYNC       PPC_BIT(17)
+#define I2C_EXTD_STAT_S_SCL             PPC_BIT(18)
+#define I2C_EXTD_STAT_S_SDA             PPC_BIT(19)
+#define I2C_EXTD_STAT_M_SCL             PPC_BIT(20)
+#define I2C_EXTD_STAT_M_SDA             PPC_BIT(21)
+#define I2C_EXTD_STAT_HIGH_WATER        PPC_BIT(22)
+#define I2C_EXTD_STAT_LOW_WATER         PPC_BIT(23)
+#define I2C_EXTD_STAT_I2C_BUSY          PPC_BIT(24)
+#define I2C_EXTD_STAT_SELF_BUSY         PPC_BIT(25)
+#define I2C_EXTD_STAT_I2C_VERSION       PPC_BITMASK(27, 31)
+
+/* I2C residual front end/back end length */
+#define I2C_RESIDUAL_LEN_REG            0xd
+#define I2C_RESIDUAL_FRONT_END          PPC_BITMASK(0, 15)
+#define I2C_RESIDUAL_BACK_END           PPC_BITMASK(16, 31)
+
+/* Port busy register */
+#define I2C_PORT_BUSY_REG               0xe
+#define I2C_SET_S_SCL_REG               0xd
+#define I2C_RESET_S_SCL_REG             0xf
+#define I2C_SET_S_SDA_REG               0x10
+#define I2C_RESET_S_SDA_REG             0x11
+
+#define PNV_I2C_FIFO_SIZE 8
+
+static I2CBus *pnv_i2c_get_bus(PnvI2C *i2c)
+{
+    uint8_t port = GETFIELD(I2C_MODE_PORT_NUM, i2c->regs[I2C_MODE_REG]);
+
+    if (port >= i2c->num_busses) {
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid bus number %d/%d\n", port,
+                      i2c->num_busses);
+        return NULL;
+    }
+    return i2c->busses[port];
+}
+
+static void pnv_i2c_update_irq(PnvI2C *i2c)
+{
+    I2CBus *bus = pnv_i2c_get_bus(i2c);
+    bool recv = !!(i2c->regs[I2C_CMD_REG] & I2C_CMD_READ_NOT_WRITE);
+    uint16_t front_end = GETFIELD(I2C_RESIDUAL_FRONT_END,
+                                  i2c->regs[I2C_RESIDUAL_LEN_REG]);
+    uint16_t back_end = GETFIELD(I2C_RESIDUAL_BACK_END,
+                                 i2c->regs[I2C_RESIDUAL_LEN_REG]);
+    uint8_t fifo_count = GETFIELD(I2C_STAT_FIFO_ENTRY_COUNT,
+                                   i2c->regs[I2C_STAT_REG]);
+    uint8_t fifo_free = PNV_I2C_FIFO_SIZE - fifo_count;
+
+    if (!bus) {
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid port\n");
+        return;
+    }
+
+    if (i2c_bus_busy(bus)) {
+        i2c->regs[I2C_STAT_REG] &= ~I2C_STAT_DATA_REQ;
+
+        if (recv) {
+            if (fifo_count >=
+                GETFIELD(I2C_WATERMARK_HIGH, i2c->regs[I2C_WATERMARK_REG])) {
+                i2c->regs[I2C_EXTD_STAT_REG] |= I2C_EXTD_STAT_HIGH_WATER;
+            } else {
+                i2c->regs[I2C_EXTD_STAT_REG] &= ~I2C_EXTD_STAT_HIGH_WATER;
+            }
+
+            if (((i2c->regs[I2C_EXTD_STAT_REG] & I2C_EXTD_STAT_HIGH_WATER) &&
+                 fifo_count != 0) || front_end == 0) {
+                i2c->regs[I2C_STAT_REG] |= I2C_STAT_DATA_REQ;
+            }
+        } else {
+            if (fifo_count <=
+                GETFIELD(I2C_WATERMARK_LOW, i2c->regs[I2C_WATERMARK_REG])) {
+                i2c->regs[I2C_EXTD_STAT_REG] |= I2C_EXTD_STAT_LOW_WATER;
+            } else {
+                i2c->regs[I2C_EXTD_STAT_REG] &= ~I2C_EXTD_STAT_LOW_WATER;
+            }
+
+            if (back_end > 0 &&
+                (fifo_free >= back_end ||
+                 (i2c->regs[I2C_EXTD_STAT_REG] & I2C_EXTD_STAT_LOW_WATER))) {
+                i2c->regs[I2C_STAT_REG] |= I2C_STAT_DATA_REQ;
+            }
+        }
+
+        if (back_end == 0 && front_end == 0) {
+            i2c->regs[I2C_STAT_REG] &= ~I2C_STAT_DATA_REQ;
+            i2c->regs[I2C_STAT_REG] |= I2C_STAT_CMD_COMP;
+
+            if (i2c->regs[I2C_CMD_REG] & I2C_CMD_WITH_STOP) {
+                i2c_end_transfer(bus);
+                i2c->regs[I2C_EXTD_STAT_REG] &=
+                    ~(I2C_EXTD_STAT_I2C_BUSY | I2C_EXTD_STAT_SELF_BUSY);
+            }
+        } else {
+            i2c->regs[I2C_STAT_REG] &= ~I2C_STAT_CMD_COMP;
+        }
+    }
+
+    /*
+     * Status and interrupt registers have nearly the same layout.
+     */
+    i2c->regs[I2C_INTR_RAW_COND_REG] = i2c->regs[I2C_STAT_REG] >> 16;
+    i2c->regs[I2C_INTR_COND_REG] =
+        i2c->regs[I2C_INTR_RAW_COND_REG] & i2c->regs[I2C_INTR_MASK_REG];
+
+    qemu_set_irq(i2c->psi_irq, i2c->regs[I2C_INTR_COND_REG] != 0);
+}
+
+static void pnv_i2c_fifo_update_count(PnvI2C *i2c)
+{
+    uint64_t stat = i2c->regs[I2C_STAT_REG];
+
+    i2c->regs[I2C_STAT_REG] = SETFIELD(I2C_STAT_FIFO_ENTRY_COUNT, stat,
+                                       fifo8_num_used(&i2c->fifo));
+}
+
+static void pnv_i2c_frontend_update(PnvI2C *i2c)
+{
+    uint64_t residual_end = i2c->regs[I2C_RESIDUAL_LEN_REG];
+    uint16_t front_end = GETFIELD(I2C_RESIDUAL_FRONT_END, residual_end);
+
+    i2c->regs[I2C_RESIDUAL_LEN_REG] =
+        SETFIELD(I2C_RESIDUAL_FRONT_END, residual_end, front_end - 1);
+}
+
+static void pnv_i2c_fifo_flush(PnvI2C *i2c)
+{
+    I2CBus *bus = pnv_i2c_get_bus(i2c);
+    uint8_t data;
+    int ret;
+
+    if (!bus) {
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid port\n");
+        return;
+    }
+    if (!i2c_bus_busy(bus)) {
+        return;
+    }
+
+    if (i2c->regs[I2C_CMD_REG] & I2C_CMD_READ_NOT_WRITE) {
+        if (fifo8_is_full(&i2c->fifo)) {
+            return;
+        }
+
+        data = i2c_recv(bus);
+        fifo8_push(&i2c->fifo, data);
+    } else {
+        if (fifo8_is_empty(&i2c->fifo)) {
+            return;
+        }
+
+        data = fifo8_pop(&i2c->fifo);
+        ret = i2c_send(bus, data);
+        if (ret) {
+            i2c->regs[I2C_STAT_REG] |= I2C_STAT_NACK_RCVD_ERR;
+            i2c_end_transfer(bus);
+        }
+    }
+
+    pnv_i2c_fifo_update_count(i2c);
+    pnv_i2c_frontend_update(i2c);
+}
+
+static void pnv_i2c_handle_cmd(PnvI2C *i2c, uint64_t val)
+{
+    I2CBus *bus = pnv_i2c_get_bus(i2c);
+    uint8_t addr = GETFIELD(I2C_CMD_DEV_ADDR, val);
+    int recv = !!(val & I2C_CMD_READ_NOT_WRITE);
+    uint32_t len_bytes = GETFIELD(I2C_CMD_LEN_BYTES, val);
+
+    if (!(val & I2C_CMD_WITH_START) && !(val & I2C_CMD_WITH_ADDR) &&
+        !(val & I2C_CMD_WITH_STOP) && !len_bytes) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid command 0x%"PRIx64"\n",
+                      val);
+        return;
+    }
+
+    if (!(i2c->regs[I2C_STAT_REG] & I2C_STAT_CMD_COMP)) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: command in progress\n");
+        return;
+    }
+
+    if (!bus) {
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid port\n");
+        return;
+    }
+
+    i2c->regs[I2C_RESIDUAL_LEN_REG] =
+        SETFIELD(I2C_RESIDUAL_FRONT_END, 0ull, len_bytes) |
+        SETFIELD(I2C_RESIDUAL_BACK_END, 0ull, len_bytes);
+
+    if (val & I2C_CMD_WITH_START) {
+        if (i2c_start_transfer(bus, addr, recv)) {
+            i2c->regs[I2C_STAT_REG] |= I2C_STAT_NACK_RCVD_ERR;
+        } else {
+            i2c->regs[I2C_EXTD_STAT_REG] |=
+                (I2C_EXTD_STAT_I2C_BUSY | I2C_EXTD_STAT_SELF_BUSY);
+            pnv_i2c_fifo_flush(i2c);
+        }
+    }
+}
+
+static void pnv_i2c_backend_update(PnvI2C *i2c)
+{
+    uint64_t residual_end = i2c->regs[I2C_RESIDUAL_LEN_REG];
+    uint16_t back_end = GETFIELD(I2C_RESIDUAL_BACK_END, residual_end);
+
+    if (!back_end) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_BKEND_ACCESS_ERR;
+        return;
+    }
+
+    i2c->regs[I2C_RESIDUAL_LEN_REG] =
+        SETFIELD(I2C_RESIDUAL_BACK_END, residual_end, back_end - 1);
+}
+
+static void pnv_i2c_fifo_in(PnvI2C *i2c)
+{
+    uint8_t data = GETFIELD(I2C_FIFO, i2c->regs[I2C_FIFO_REG]);
+    I2CBus *bus = pnv_i2c_get_bus(i2c);
+
+    if (!bus) {
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid port\n");
+        return;
+    }
+
+    if (!i2c_bus_busy(bus)) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: no command in progress\n");
+        return;
+    }
+
+    if (i2c->regs[I2C_CMD_REG] & I2C_CMD_READ_NOT_WRITE) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: read command in progress\n");
+        return;
+    }
+
+    if (fifo8_is_full(&i2c->fifo)) {
+        if (!(i2c->regs[I2C_MODE_REG] & I2C_MODE_PACING_ALLOW)) {
+            i2c->regs[I2C_STAT_REG] |= I2C_STAT_BKEND_OVERRUN_ERR;
+        }
+        return;
+    }
+
+    fifo8_push(&i2c->fifo, data);
+    pnv_i2c_fifo_update_count(i2c);
+    pnv_i2c_backend_update(i2c);
+    pnv_i2c_fifo_flush(i2c);
+}
+
+static void pnv_i2c_fifo_out(PnvI2C *i2c)
+{
+    uint8_t data;
+    I2CBus *bus = pnv_i2c_get_bus(i2c);
+
+    if (!bus) {
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid port\n");
+        return;
+    }
+
+    if (!i2c_bus_busy(bus)) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: no command in progress\n");
+        return;
+    }
+
+    if (!(i2c->regs[I2C_CMD_REG] & I2C_CMD_READ_NOT_WRITE)) {
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: write command in progress\n");
+        return;
+    }
+
+    if (fifo8_is_empty(&i2c->fifo)) {
+        if (!(i2c->regs[I2C_MODE_REG] & I2C_MODE_PACING_ALLOW)) {
+            i2c->regs[I2C_STAT_REG] |= I2C_STAT_BKEND_OVERRUN_ERR;
+        }
+        return;
+    }
+
+    data = fifo8_pop(&i2c->fifo);
+
+    i2c->regs[I2C_FIFO_REG] = SETFIELD(I2C_FIFO, 0ull, data);
+    pnv_i2c_fifo_update_count(i2c);
+    pnv_i2c_backend_update(i2c);
+}
+
+static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
+                                   unsigned size)
+{
+    PnvI2C *i2c = PNV_I2C(opaque);
+    uint32_t offset = addr >> 3;
+    uint64_t val = -1;
+    int i;
+
+    switch (offset) {
+    case I2C_STAT_REG:
+        val = i2c->regs[offset];
+        break;
+
+    case I2C_FIFO_REG:
+        pnv_i2c_fifo_out(i2c);
+        val = i2c->regs[offset];
+        break;
+
+    case I2C_PORT_BUSY_REG: /* compute busy bit for each port  */
+        val = 0;
+        for (i = 0; i < i2c->num_busses; i++) {
+            val |= i2c_bus_busy(i2c->busses[i]) << i;
+        }
+        break;
+
+    case I2C_CMD_REG:
+    case I2C_MODE_REG:
+    case I2C_WATERMARK_REG:
+    case I2C_INTR_MASK_REG:
+    case I2C_INTR_RAW_COND_REG:
+    case I2C_INTR_COND_REG:
+    case I2C_EXTD_STAT_REG:
+    case I2C_RESIDUAL_LEN_REG:
+        val = i2c->regs[offset];
+        break;
+    default:
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: read at register: 0x%"
+                      HWADDR_PRIx "\n", addr >> 3);
+    }
+
+    pnv_i2c_update_irq(i2c);
+
+    return val;
+}
+
+static void pnv_i2c_xscom_write(void *opaque, hwaddr addr,
+                                uint64_t val, unsigned size)
+{
+    PnvI2C *i2c = PNV_I2C(opaque);
+    uint32_t offset = addr >> 3;
+
+    switch (offset) {
+    case I2C_MODE_REG:
+        {
+            i2c->regs[offset] = val;
+            I2CBus *bus = pnv_i2c_get_bus(i2c);
+            if (!bus) {
+                qemu_log_mask(LOG_GUEST_ERROR, "I2C: invalid port\n");
+                return;
+            }
+            if (i2c_bus_busy(bus)) {
+                i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+                qemu_log_mask(LOG_GUEST_ERROR, "I2C: command in progress\n");
+            }
+        }
+        break;
+
+    case I2C_CMD_REG:
+        i2c->regs[offset] = val;
+        pnv_i2c_handle_cmd(i2c, val);
+        break;
+
+    case I2C_FIFO_REG:
+        i2c->regs[offset] = val;
+        pnv_i2c_fifo_in(i2c);
+        break;
+
+    case I2C_WATERMARK_REG:
+        i2c->regs[offset] = val;
+        break;
+
+    case I2C_RESET_I2C_REG:
+        i2c->regs[I2C_MODE_REG] = 0;
+        i2c->regs[I2C_CMD_REG] = 0;
+        i2c->regs[I2C_WATERMARK_REG] = 0;
+        i2c->regs[I2C_INTR_MASK_REG] = 0;
+        i2c->regs[I2C_INTR_COND_REG] = 0;
+        i2c->regs[I2C_INTR_RAW_COND_REG] = 0;
+        i2c->regs[I2C_STAT_REG] = 0;
+        i2c->regs[I2C_RESIDUAL_LEN_REG] = 0;
+        i2c->regs[I2C_EXTD_STAT_REG] &=
+            (I2C_EXTD_STAT_FIFO_SIZE | I2C_EXTD_STAT_I2C_VERSION);
+        break;
+
+    case I2C_RESET_ERRORS:
+        i2c->regs[I2C_STAT_REG] &= ~I2C_STAT_ANY_ERR;
+        i2c->regs[I2C_RESIDUAL_LEN_REG] = 0;
+        i2c->regs[I2C_EXTD_STAT_REG] &=
+            (I2C_EXTD_STAT_FIFO_SIZE | I2C_EXTD_STAT_I2C_VERSION);
+        fifo8_reset(&i2c->fifo);
+        break;
+
+    case I2C_INTR_MASK_REG:
+        i2c->regs[offset] = val;
+        break;
+
+    case I2C_INTR_MASK_OR_REG:
+        i2c->regs[I2C_INTR_MASK_REG] |= val;
+        break;
+
+    case I2C_INTR_MASK_AND_REG:
+        i2c->regs[I2C_INTR_MASK_REG] &= val;
+        break;
+
+    case I2C_PORT_BUSY_REG:
+    case I2C_SET_S_SCL_REG:
+    case I2C_RESET_S_SCL_REG:
+    case I2C_SET_S_SDA_REG:
+    case I2C_RESET_S_SDA_REG:
+        i2c->regs[offset] = val;
+        break;
+    default:
+        i2c->regs[I2C_STAT_REG] |= I2C_STAT_INVALID_CMD;
+        qemu_log_mask(LOG_GUEST_ERROR, "I2C: write at register: 0x%"
+                      HWADDR_PRIx " val=0x%"PRIx64"\n", addr >> 3, val);
+    }
+
+    pnv_i2c_update_irq(i2c);
+}
+
+static const MemoryRegionOps pnv_i2c_xscom_ops = {
+    .read = pnv_i2c_xscom_read,
+    .write = pnv_i2c_xscom_write,
+    .valid.min_access_size = 8,
+    .valid.max_access_size = 8,
+    .impl.min_access_size = 8,
+    .impl.max_access_size = 8,
+    .endianness = DEVICE_BIG_ENDIAN,
+};
+
+static int pnv_i2c_bus_dt_xscom(PnvI2C *i2c, void *fdt,
+                                int offset, int index)
+{
+    int i2c_bus_offset;
+    const char i2c_compat[] =
+        "ibm,opal-i2c\0ibm,power8-i2c-port\0ibm,power9-i2c-port";
+    g_autofree char *i2c_port_name = NULL;
+    g_autofree char *name = g_strdup_printf("i2c-bus@%x", index);
+
+    i2c_bus_offset = fdt_add_subnode(fdt, offset, name);
+    _FDT(i2c_bus_offset);
+
+    _FDT((fdt_setprop_cell(fdt, i2c_bus_offset, "reg", index)));
+    _FDT((fdt_setprop_cell(fdt, i2c_bus_offset, "#address-cells", 1)));
+    _FDT((fdt_setprop_cell(fdt, i2c_bus_offset, "#size-cells", 0)));
+    _FDT(fdt_setprop(fdt, i2c_bus_offset, "compatible", i2c_compat,
+                     sizeof(i2c_compat)));
+    _FDT((fdt_setprop_cell(fdt, i2c_bus_offset, "bus-frequency", 400000)));
+
+    i2c_port_name = g_strdup_printf("p8_%08x_e%dp%d", i2c->chip->chip_id,
+                                    i2c->engine, index);
+    _FDT(fdt_setprop_string(fdt, i2c_bus_offset, "ibm,port-name",
+                            i2c_port_name));
+    return 0;
+}
+
+#define XSCOM_BUS_FREQUENCY 466500000
+#define I2C_CLOCK_FREQUENCY (XSCOM_BUS_FREQUENCY / 4)
+
+static int pnv_i2c_dt_xscom(PnvXScomInterface *dev, void *fdt,
+                            int offset)
+{
+    PnvI2C *i2c = PNV_I2C(dev);
+    int i2c_offset;
+    const char i2c_compat[] = "ibm,power8-i2cm\0ibm,power9-i2cm";
+    uint32_t i2c_pcba = PNV9_XSCOM_I2CM_BASE +
+        i2c->engine * PNV9_XSCOM_I2CM_SIZE;
+    uint32_t reg[2] = {
+        cpu_to_be32(i2c_pcba),
+        cpu_to_be32(PNV9_XSCOM_I2CM_SIZE)
+    };
+    int i;
+    g_autofree char *name = g_strdup_printf("i2cm@%x", i2c_pcba);
+
+    i2c_offset = fdt_add_subnode(fdt, offset, name);
+    _FDT(i2c_offset);
+
+    _FDT(fdt_setprop(fdt, i2c_offset, "reg", reg, sizeof(reg)));
+
+    _FDT((fdt_setprop_cell(fdt, i2c_offset, "#address-cells", 1)));
+    _FDT((fdt_setprop_cell(fdt, i2c_offset, "#size-cells", 0)));
+    _FDT(fdt_setprop(fdt, i2c_offset, "compatible", i2c_compat,
+                     sizeof(i2c_compat)));
+    _FDT((fdt_setprop_cell(fdt, i2c_offset, "chip-engine#", i2c->engine)));
+    _FDT((fdt_setprop_cell(fdt, i2c_offset, "clock-frequency",
+                           I2C_CLOCK_FREQUENCY)));
+
+    for (i = 0; i < i2c->num_busses; i++) {
+        pnv_i2c_bus_dt_xscom(i2c, fdt, i2c_offset, i);
+    }
+    return 0;
+}
+
+static void pnv_i2c_reset(void *dev)
+{
+    PnvI2C *i2c = PNV_I2C(dev);
+
+    memset(i2c->regs, 0, sizeof(i2c->regs));
+
+    i2c->regs[I2C_STAT_REG] = I2C_STAT_CMD_COMP;
+    i2c->regs[I2C_EXTD_STAT_REG] =
+        SETFIELD(I2C_EXTD_STAT_FIFO_SIZE, 0ull, PNV_I2C_FIFO_SIZE) |
+        SETFIELD(I2C_EXTD_STAT_I2C_VERSION, 0ull, 23); /* last version */
+
+    fifo8_reset(&i2c->fifo);
+}
+
+static void pnv_i2c_realize(DeviceState *dev, Error **errp)
+{
+    PnvI2C *i2c = PNV_I2C(dev);
+    int i;
+
+    assert(i2c->chip);
+
+    pnv_xscom_region_init(&i2c->xscom_regs, OBJECT(i2c), &pnv_i2c_xscom_ops,
+                          i2c, "xscom-i2c", PNV9_XSCOM_I2CM_SIZE);
+
+    i2c->busses = g_new(I2CBus *, i2c->num_busses);
+    for (i = 0; i < i2c->num_busses; i++) {
+        char name[32];
+
+        snprintf(name, sizeof(name), TYPE_PNV_I2C ".%d", i);
+        i2c->busses[i] = i2c_init_bus(dev, name);
+    }
+
+    fifo8_create(&i2c->fifo, PNV_I2C_FIFO_SIZE);
+
+    qemu_register_reset(pnv_i2c_reset, dev);
+
+    qdev_init_gpio_out(DEVICE(dev), &i2c->psi_irq, 1);
+}
+
+static Property pnv_i2c_properties[] = {
+    DEFINE_PROP_LINK("chip", PnvI2C, chip, TYPE_PNV_CHIP, PnvChip *),
+    DEFINE_PROP_UINT32("engine", PnvI2C, engine, 1),
+    DEFINE_PROP_UINT32("num-busses", PnvI2C, num_busses, 1),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void pnv_i2c_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    PnvXScomInterfaceClass *xscomc = PNV_XSCOM_INTERFACE_CLASS(klass);
+
+    xscomc->dt_xscom = pnv_i2c_dt_xscom;
+
+    dc->desc = "PowerNV I2C";
+    dc->realize = pnv_i2c_realize;
+    device_class_set_props(dc, pnv_i2c_properties);
+}
+
+static const TypeInfo pnv_i2c_info = {
+    .name          = TYPE_PNV_I2C,
+    .parent        = TYPE_DEVICE,
+    .instance_size = sizeof(PnvI2C),
+    .class_init    = pnv_i2c_class_init,
+    .interfaces    = (InterfaceInfo[]) {
+        { TYPE_PNV_XSCOM_INTERFACE },
+        { }
+    }
+};
+
+static void pnv_i2c_register_types(void)
+{
+    type_register_static(&pnv_i2c_info);
+}
+
+type_init(pnv_i2c_register_types);
diff --git a/include/hw/ppc/pnv_i2c.h b/include/hw/ppc/pnv_i2c.h
new file mode 100644
index 0000000000..1a37730f1e
--- /dev/null
+++ b/include/hw/ppc/pnv_i2c.h
@@ -0,0 +1,38 @@
+/*
+ * QEMU PowerPC PowerNV Processor I2C model
+ *
+ * Copyright (c) 2019-2023, IBM Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef PPC_PNV_I2C_H
+#define PPC_PNV_I2C_H
+
+#include "hw/ppc/pnv.h"
+#include "hw/i2c/i2c.h"
+#include "qemu/fifo8.h"
+
+#define TYPE_PNV_I2C "pnv-i2c"
+#define PNV_I2C(obj) OBJECT_CHECK(PnvI2C, (obj), TYPE_PNV_I2C)
+
+#define PNV_I2C_REGS 0x20
+
+typedef struct PnvI2C {
+    DeviceState parent;
+
+    struct PnvChip *chip;
+
+    qemu_irq psi_irq;
+
+    uint64_t regs[PNV_I2C_REGS];
+    uint32_t engine;
+    uint32_t num_busses;
+    I2CBus **busses;
+
+    MemoryRegion xscom_regs;
+
+    Fifo8 fifo;
+} PnvI2C;
+
+#endif /* PPC_PNV_I2C_H */
diff --git a/include/hw/ppc/pnv_xscom.h b/include/hw/ppc/pnv_xscom.h
index 35b19610f7..056392ab60 100644
--- a/include/hw/ppc/pnv_xscom.h
+++ b/include/hw/ppc/pnv_xscom.h
@@ -90,6 +90,9 @@ struct PnvXScomInterfaceClass {
     ((uint64_t)(((core) & 0x1C) + 0x40) << 22)
 #define PNV9_XSCOM_EQ_SIZE        0x100000
 
+#define PNV9_XSCOM_I2CM_BASE      0xa0000
+#define PNV9_XSCOM_I2CM_SIZE      0x1000
+
 #define PNV9_XSCOM_OCC_BASE       PNV_XSCOM_OCC_BASE
 #define PNV9_XSCOM_OCC_SIZE       0x8000
 
-- 
2.41.0