> Subject: [PATCH 02/19] hw/i3c: Add bus support
> 
> Adds an I3C bus and a target class.
> The bus supports:
> - I3C data transmission and reception
> - CCCs (including ENTDAA)
> - IBIs
> - legacy I2C transactions
> 
> General usage of the bus is similar to I2C. Users are expected to initialize 
> a bus
> via i3c_init_bus, and use the bus returned from the init function to do
> transactions on the bus.
> 
> In order to handle IBIs, the controller provides callbacks to handle 
> receiving an
> IBI from a target, receiving (optional) additional IBI bytes from a target, 
> and
> handling when a target is done with its IBI.
> 
> Similarly, target creation is done via i3c_target_create_simple and users use
> the provided I3CTarget to handle transactions.
> The target has functions provided that it can use to invoke an IBI and send
> additional bytes.
> 
> Along with the send, recv, and event callbacks that are expected of an I3C
> target, which are similar to I2C, there is a separate callback for CCC 
> handling.
> This is to help encapsulate CCC handling and keep it separate from
> target-specific read/write functionality.
> 
> To avoid repition for required CCCs among I3C targets, there is some 
> class-level
> CCC handling added. The CCC is then passed to the target in case it needs to
> handle it in some way.
> 
> Signed-off-by: Joe Komlodi <[email protected]>
> 
> Reviewed-by: Patrick Venture <[email protected]>
> Reviewed-by: Titus Rwantare <[email protected]>
> ---
>  hw/i3c/core.c        | 652
> +++++++++++++++++++++++++++++++++++++++++++
>  hw/i3c/meson.build   |   1 +
>  hw/i3c/trace-events  |  16 ++
>  include/hw/i3c/i3c.h | 277 ++++++++++++++++++
>  4 files changed, 946 insertions(+)
>  create mode 100644 hw/i3c/core.c
>  create mode 100644 include/hw/i3c/i3c.h
> 
> diff --git a/hw/i3c/core.c b/hw/i3c/core.c new file mode 100644 index
> 0000000000..117d9da7ac
> --- /dev/null
> +++ b/hw/i3c/core.c
> @@ -0,0 +1,652 @@
> +/*
> + * QEMU I3C bus interface.
> + *
> + * Copyright 2025 Google LLC
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later  */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/log.h"
> +#include "qapi/error.h"
> +#include "trace.h"
> +#include "hw/i3c/i3c.h"
> +#include "hw/qdev-properties.h"
> +
> +/*
> + * In test mode (enabled by ENTTM CCC) we're supposed to send a random
> +PID
> + * during ENTDAA, so we'll just send "QEMU".
> + */
> +#define TEST_MODE_PROVISIONED_ID 0x0000554d4551ULL
> +
> +static const Property i3c_props[] = {
> +    DEFINE_PROP_UINT8("static-address", struct I3CTarget, static_address,
> 0),
> +    DEFINE_PROP_UINT8("dcr", struct I3CTarget, dcr, 0),
> +    DEFINE_PROP_UINT8("bcr", struct I3CTarget, bcr, 0),
> +    DEFINE_PROP_UINT64("pid", struct I3CTarget, pid, 0), };
> +
> +static const TypeInfo i3c_bus_info = {
> +    .name = TYPE_I3C_BUS,
> +    .parent = TYPE_BUS,
> +    .instance_size = sizeof(I3CBus),
> +    .class_size = sizeof(I3CBusClass),
> +};
> +
> +I3CBus *i3c_init_bus(DeviceState *parent, const char *name) {
> +    return i3c_init_bus_type(TYPE_I3C_BUS, parent, name); }
> +
> +I3CBus *i3c_init_bus_type(const char *type, DeviceState *parent,
> +                          const char *name) {
> +    I3CBus *bus;
> +
> +    bus = I3C_BUS(qbus_new(type, parent, name));
> +    QLIST_INIT(&bus->current_devs);
> +    bus->broadcast = false;
> +    bus->in_entdaa = false;
> +    bus->in_ccc = false;
> +
> +    /* I2C init. */
> +    g_autofree gchar *i2c_bus_name = g_strdup_printf("%s-legacy-i2c",
> name);
> +    bus->i2c_bus = i2c_init_bus(parent, i2c_bus_name);
> +
> +    return bus;
> +}
> +
> +bool i3c_bus_busy(I3CBus *bus)
> +{
> +    return !QLIST_EMPTY(&bus->current_devs); }
> +
> +static bool i3c_target_match(I3CTarget *candidate, uint8_t address,
> +                             bool is_recv, bool broadcast, bool
> +in_entdaa) {
> +    /* Once a target has a dynamic address, it only responds to that. */
> +    uint8_t targ_addr = candidate->address ? candidate->address :
> +
> candidate->static_address;
> +
> +    if (in_entdaa) {
> +        if (address != I3C_BROADCAST) {
> +            g_autofree char *path =
> +                object_get_canonical_path(OBJECT(candidate));
> +            qemu_log_mask(LOG_GUEST_ERROR, "%s: I3C Address 0x%.2x
> sent during "
> +                          "ENTDAA instead of a broadcast address\n",
> +                          path, address);
> +            return false;
> +        }
> +
> +        /*
> +         * Targets should only ACK ENTDAA broadcasts if they have no
> dynamic
> +         * address.
> +         */
> +        return candidate->address == 0;
> +    }
> +
> +    /* Return if our addresses match, or if it's a broadcast. */
> +    return targ_addr == address || broadcast; }
> +
> +bool i3c_target_match_and_add(I3CBus *bus, I3CTarget *target, uint8_t
> address,
> +                              enum I3CEvent event) {
> +    I3CTargetClass *tc = I3C_TARGET_GET_CLASS(target);
> +    bool matched = tc->target_match(target, address, event ==
> I3C_START_RECV,
> +                                    bus->broadcast, bus->in_entdaa);
> +
> +    if (matched) {
> +        I3CNode *node = g_new(struct I3CNode, 1);
> +        node->target = target;
> +        QLIST_INSERT_HEAD(&bus->current_devs, node, next);
> +    }
> +    return matched;
> +}
> +
> +bool i3c_scan_bus(I3CBus *bus, uint8_t address, enum I3CEvent event) {
> +    BusChild *child;
> +    I3CNode *node, *next;
> +
> +    /* Clear out any devices from a previous (re-)START. */
> +    QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
> +        QLIST_REMOVE(node, next);
> +        g_free(node);
> +    }
> +
> +    QTAILQ_FOREACH(child, &bus->qbus.children, sibling) {
> +        DeviceState *qdev = child->child;
> +        I3CTarget *target = I3C_TARGET(qdev);
> +
> +        if (i3c_target_match_and_add(bus, target, address, event)) {
> +            return true;
> +        }
> +    }
> +
> +    /* No one on the bus could respond. */
> +    return false;
> +}
> +
> +/* Class-level event handling, since we do some CCCs at the class
> +level. */ static int i3c_target_event(I3CTarget *t, enum I3CEvent
> +event) {
> +    I3CTargetClass *tc = I3C_TARGET_GET_CLASS(t);
> +    trace_i3c_target_event(t->address, event);
> +
> +    if (event == I3C_STOP) {
> +        t->curr_ccc = 0;
> +        t->ccc_byte_offset = 0;
> +        t->in_ccc = false;
> +    }
> +    return tc->event(t, event);
> +}
> +
> +/*
> + * Sends a START or repeated START and the address for an I3C transaction.
> + *
> + * This function returns 0 if a device on the bus was able to respond
> +to the
> + * address, and non-zero otherwise.
> + * A non-zero return represents a NACK.
> + */
> +static int i3c_do_start_transfer(I3CBus *bus, uint8_t address,
> +                                 enum I3CEvent event) {
> +    I3CTargetClass *tc;
> +    I3CNode *node;
> +
> +    if (address == I3C_BROADCAST) {
> +        bus->broadcast = true;
> +        /* If we're not in ENTDAA, a broadcast is the start of a new CCC. */
> +        if (!bus->in_entdaa) {
> +            bus->in_ccc = false;
> +        }
> +    } else {
> +        bus->broadcast = false;
> +    }
> +
> +    /* No one responded to the address, NACK it. */
> +    if (!i3c_scan_bus(bus, address, event)) {
> +        return -1;
> +    }
> +
> +    QLIST_FOREACH(node, &bus->current_devs, next) {
> +        I3CTarget *t = node->target;
> +
> +        tc = I3C_TARGET_GET_CLASS(t);
> +        if (tc->event) {
> +            int rv = i3c_target_event(t, event);
> +            if (rv && !bus->broadcast) {
> +                return rv;
> +            }
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +int i3c_start_transfer(I3CBus *bus, uint8_t address, bool is_recv) {
> +    trace_i3c_start_transfer(address, is_recv);
> +    return i3c_do_start_transfer(bus, address, is_recv
> +                                               ? I3C_START_RECV
> +                                               :
> I3C_START_SEND); }
> +
> +int i3c_start_recv(I3CBus *bus, uint8_t address) {
> +    trace_i3c_start_transfer(address, true);
> +    return i3c_do_start_transfer(bus, address, I3C_START_RECV); }
> +
> +int i3c_start_send(I3CBus *bus, uint8_t address) {
> +    trace_i3c_start_transfer(address, false);
> +    return i3c_do_start_transfer(bus, address, I3C_START_SEND); }
> +
> +void i3c_end_transfer(I3CBus *bus)
> +{
> +    I3CTargetClass *tc;
> +    I3CNode *node, *next;
> +
> +    trace_i3c_end_transfer();
> +
> +    /*
> +     * If we're in ENTDAA, we need to notify all devices when ENTDAA is
> done.
> +     * This is because everyone initially participates due to the broadcast,
> +     * but gradually drops out as they get assigned addresses.
> +     * Since the current_devs list only stores who's currently participating,
> +     * and not everyone who previously participated, we send the STOP to
> all
> +     * children.
> +     */
> +    if (bus->in_entdaa) {
> +        BusChild *child;
> +
> +        QTAILQ_FOREACH(child, &bus->qbus.children, sibling) {
> +            DeviceState *qdev = child->child;
> +            I3CTarget *t = I3C_TARGET(qdev);
> +            tc = I3C_TARGET_GET_CLASS(t);
> +            if (tc->event) {
> +                i3c_target_event(t, I3C_STOP);
> +            }
> +        }
> +    } else {
> +        QLIST_FOREACH_SAFE(node, &bus->current_devs, next, next) {
> +            I3CTarget *t = node->target;
> +            tc = I3C_TARGET_GET_CLASS(t);
> +            if (tc->event) {
> +                i3c_target_event(t, I3C_STOP);
> +            }
> +            QLIST_REMOVE(node, next);
> +            g_free(node);
> +        }
> +    }
> +    bus->broadcast = false;
> +    bus->in_entdaa = false;
> +    bus->in_ccc = false;
> +}
> +
> +/*
> + * Any CCCs that are universal across all I3C devices should be handled here.
> + * Once they're handled, we pass the CCC up to the I3C target to do
> +anything
> + * else it may want with the bytes.
> + */
> +static int i3c_target_handle_ccc_write(I3CTarget *t, const uint8_t *data,
> +                                       uint32_t num_to_send,
> uint32_t
> +*num_sent) {
> +    I3CTargetClass *tc = I3C_TARGET_GET_CLASS(t);
> +    *num_sent = 0;
> +
> +    /* Is this the start of a new CCC? */
> +    if (!t->in_ccc) {
> +        t->curr_ccc = *data;
> +        t->in_ccc = true;
> +        *num_sent = 1;
> +        trace_i3c_target_handle_ccc(t->address, t->curr_ccc);
> +    }
> +
> +    switch (t->curr_ccc) {
> +    case I3C_CCC_ENTDAA:
> +        /*
> +         * This is the last byte of ENTDAA, the controller is assigning us an
> +         * address.
> +         */
> +        if (t->ccc_byte_offset == 8) {
> +            t->address = *data;
> +            t->in_ccc = false;
> +            t->curr_ccc = 0;
> +            t->ccc_byte_offset = 0;
> +            *num_sent = 1;
> +        }
> +        break;
> +    case I3C_CCCD_SETDASA:
> +        t->address = t->static_address;
> +        break;
> +    case I3C_CCC_SETAASA:
> +        t->address = t->static_address;
> +        break;
> +    case I3C_CCC_RSTDAA:
> +        t->address = 0;
> +        break;
> +    case I3C_CCCD_SETNEWDA:
> +        /* If this isn't the CCC byte, it's our new address. */
> +        if (*num_sent == 0) {
> +            t->address = *data;
> +            *num_sent = 1;
> +        }
> +        break;
> +    case I3C_CCC_ENTTM:
> +        /*
> +         * If there are still more to look at, the next byte is the test mode
> +         * byte.
> +         */
> +        if (*num_sent != num_to_send) {
> +            /* Enter test mode if the byte is non-zero. Otherwise exit. */
> +            t->in_test_mode = !!data[*num_sent];
> +            ++*num_sent;
> +        }
> +        break;
> +    /* Ignore other CCCs it's better to handle on a device-by-device basis. 
> */
> +    default:
> +        break;
> +    }
> +    return tc->handle_ccc_write(t, data, num_to_send, num_sent); }
> +
> +int i3c_send_byte(I3CBus *bus, uint8_t data) {
> +    /*
> +     * Ignored, the caller can determine how many were sent based on if
> this was
> +     * ACKed/NACKed.
> +     */
> +    uint32_t num_sent;
> +    return i3c_send(bus, &data, 1, &num_sent); }
> +
> +int i3c_send(I3CBus *bus, const uint8_t *data, uint32_t num_to_send,
> +             uint32_t *num_sent)
> +{
> +    I3CTargetClass *tc;
> +    I3CTarget *t;
> +    I3CNode *node;
> +    int ret = 0;
> +
> +    /* If this message is a broadcast and no CCC has been found, grab it. */
> +    if (bus->broadcast && !bus->in_ccc) {
> +        bus->ccc = *data;
> +        bus->in_ccc = true;
> +        /*
> +         * We need to keep track if we're currently in ENTDAA.
> +         * On any other CCC, the CCC is over on a RESTART or STOP, but
> ENTDAA
> +         * is only over on a STOP.
> +         */
> +        if (bus->ccc == I3C_CCC_ENTDAA) {
> +            bus->in_entdaa = true;
> +        }
> +    }
> +
> +    QLIST_FOREACH(node, &bus->current_devs, next) {
> +        t = node->target;
> +        tc = I3C_TARGET_GET_CLASS(t);
> +        if (bus->in_ccc) {
> +            if (!tc->handle_ccc_write) {
> +                ret = -1;
> +                continue;
> +            }
> +            ret = i3c_target_handle_ccc_write(t, data, num_to_send,
> num_sent);
> +            /* Targets should only NACK on a direct CCC. */
> +            if (ret && !CCC_IS_DIRECT(bus->ccc)) {
> +                ret = 0;
> +            }
> +        } else {
> +            if (tc->send) {
> +                ret = ret || tc->send(t, data, num_to_send, num_sent);
> +            } else {
> +                ret = -1;
> +            }
> +        }
> +    }
> +
> +    trace_i3c_send(*num_sent, num_to_send, ret == 0);
> +
> +    return ret ? -1 : 0;
> +}
> +
> +static int i3c_target_handle_ccc_read(I3CTarget *t, uint8_t *data,
> +                                      uint32_t num_to_read,
> uint32_t
> +*num_read) {
> +    I3CTargetClass *tc = I3C_TARGET_GET_CLASS(t);
> +    uint8_t read_count = 0;
> +    uint64_t pid;
> +
> +    switch (t->curr_ccc) {
> +    case I3C_CCC_ENTDAA:
> +        if (t->in_test_mode) {
> +            pid = TEST_MODE_PROVISIONED_ID;
> +        } else {
> +            pid = t->pid;
> +        }
> +        /* Return the 6-byte PID, followed by BCR then DCR. */
> +        while (t->ccc_byte_offset < 6) {
> +            if (read_count >= num_to_read) {
> +                break;
> +            }
> +            data[read_count] = (pid >> (t->ccc_byte_offset * 8)) & 0xff;
> +            t->ccc_byte_offset++;
> +            read_count++;
> +        }
> +        if (read_count < num_to_read) {
> +            data[read_count] = t->bcr;
> +            t->ccc_byte_offset++;
> +            read_count++;
> +        }
> +        if (read_count < num_to_read) {
> +            data[read_count] = t->dcr;
> +            t->ccc_byte_offset++;
> +            read_count++;
> +        }
> +        *num_read = read_count;
> +        break;
> +    case I3C_CCCD_GETPID:
> +        while (t->ccc_byte_offset < 6) {
> +            if (read_count >= num_to_read) {
> +                break;
> +            }
> +            data[read_count] = (t->pid >> (t->ccc_byte_offset * 8)) & 0xff;
> +            t->ccc_byte_offset++;
> +            read_count++;
> +        }
> +        *num_read = read_count;
> +        break;
> +    case I3C_CCCD_GETBCR:
> +        *data = t->bcr;
> +        *num_read = 1;
> +        break;
> +    case I3C_CCCD_GETDCR:
> +        *data = t->dcr;
> +        *num_read = 1;
> +        break;
> +    default:
> +        /* Unhandled on the I3CTarget class level. */
> +        break;
> +    }
> +
> +    return tc->handle_ccc_read(t, data, num_to_read, num_read); }
> +
> +int i3c_recv_byte(I3CBus *bus, uint8_t *data) {
> +     /*
> +      * Ignored, the caller can determine how many bytes were read based
> on if
> +      * this is ACKed/NACKed.
> +      */
> +    uint32_t num_read;
> +    return i3c_recv(bus, data, 1, &num_read); }
> +
> +int i3c_recv(I3CBus *bus, uint8_t *data, uint32_t num_to_read,
> +             uint32_t *num_read)
> +{
> +    int ret = 0;
> +    I3CTargetClass *tc;
> +    I3CTarget *t;
> +
> +    *data = 0xff;
> +    if (!QLIST_EMPTY(&bus->current_devs)) {
> +        tc =
> I3C_TARGET_GET_CLASS(QLIST_FIRST(&bus->current_devs)->target);
> +        t = QLIST_FIRST(&bus->current_devs)->target;
> +        if (bus->in_ccc) {
> +            if (!tc->handle_ccc_read) {
> +                return -1;
> +            }
> +            ret = i3c_target_handle_ccc_read(t, data, num_to_read,
> num_read);
> +        } else {
> +            if (tc->recv) {
> +                /*
> +                 * Targets cannot NACK on a direct transfer, so the data
> +                 * is returned directly.
> +                 */
> +                *num_read = tc->recv(t, data, num_to_read);
> +            }
> +        }
> +    }
> +
> +    trace_i3c_recv(*num_read, num_to_read, ret == 0);
> +
> +    return ret;
> +}
> +
> +void i3c_nack(I3CBus *bus)
> +{
> +    I3CTargetClass *tc;
> +    I3CNode *node;
> +
> +    if (QLIST_EMPTY(&bus->current_devs)) {
> +        return;
> +    }
> +
> +    QLIST_FOREACH(node, &bus->current_devs, next) {
> +        tc = I3C_TARGET_GET_CLASS(node->target);
> +        if (tc->event) {
> +            i3c_target_event(node->target, I3C_NACK);
> +        }
> +    }
> +}
> +
> +int i3c_target_send_ibi(I3CTarget *t, uint8_t addr, bool is_recv) {
> +    I3CBus *bus = I3C_BUS(t->qdev.parent_bus);
> +    I3CBusClass *bc = I3C_BUS_GET_CLASS(bus);
> +    trace_i3c_target_send_ibi(addr, is_recv);
> +    return bc->ibi_handle(bus, addr, is_recv); }
> +
> +int i3c_target_send_ibi_bytes(I3CTarget *t, uint8_t data) {
> +    I3CBus *bus = I3C_BUS(t->qdev.parent_bus);
> +    I3CBusClass *bc = I3C_BUS_GET_CLASS(bus);
> +    trace_i3c_target_send_ibi_bytes(data);
> +    return bc->ibi_recv(bus, data);
> +}
> +
> +int i3c_target_ibi_finish(I3CTarget *t, uint8_t data) {
> +    I3CBus *bus = I3C_BUS(t->qdev.parent_bus);
> +    I3CBusClass *bc = I3C_BUS_GET_CLASS(bus);
> +    trace_i3c_target_ibi_finish();
> +    return bc->ibi_finish(bus);
> +}
> +
> +static bool i3c_addr_is_rsvd(uint8_t addr) {
> +    const bool is_rsvd[255] = {
> +        [0x00] = true,
> +        [0x01] = true,
> +        [0x02] = true,
> +        [0x3e] = true,
> +        [0x5e] = true,
> +        [0x6e] = true,
> +        [0x76] = true,
> +        [0x7a] = true,
> +        [0x7c] = true,
> +        [0x7e] = true,
> +        [0x7f] = true,
> +    };
> +
> +    return is_rsvd[addr];
> +}
> +
> +I3CTarget *i3c_target_new(const char *name, uint8_t addr, uint8_t dcr,
> +                          uint8_t bcr, uint64_t pid) {
> +    DeviceState *dev;
> +
> +    dev = qdev_new(name);
> +    qdev_prop_set_uint8(dev, "static-address", addr);
> +    qdev_prop_set_uint8(dev, "dcr", dcr);
> +    qdev_prop_set_uint8(dev, "bcr", bcr);
> +    qdev_prop_set_uint64(dev, "pid", pid);
> +
> +    if (i3c_addr_is_rsvd(addr)) {
> +        g_autofree char *path = object_get_canonical_path(OBJECT(dev));
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: I3C target created with
> reserved "
> +                      "address 0x%.2x\n", path, addr);
> +    }
> +    return I3C_TARGET(dev);
> +}
> +
> +bool i3c_target_realize_and_unref(I3CTarget *dev, I3CBus *bus, Error
> +**errp) {
> +    return qdev_realize_and_unref(&dev->qdev, &bus->qbus, errp); }
> +
> +I3CTarget *i3c_target_create_simple(I3CBus *bus, const char *name, uint8_t
> addr,
> +                                    uint8_t dcr, uint8_t bcr, uint64_t
> +pid) {
> +    I3CTarget *dev = i3c_target_new(name, addr, dcr, bcr, pid);
> +    dev->address = 0;
> +    i3c_target_realize_and_unref(dev, bus, &error_abort);
> +
> +    return dev;
> +}
> +
> +/* Legacy I2C functions. */
> +void legacy_i2c_nack(I3CBus *bus)
> +{
> +    trace_legacy_i2c_nack();
> +    i2c_nack(bus->i2c_bus);
> +}
> +
> +uint8_t legacy_i2c_recv(I3CBus *bus)
> +{
> +    uint8_t byte = i2c_recv(bus->i2c_bus);
> +    trace_legacy_i2c_recv(byte);
> +    return byte;
> +}
> +
> +int legacy_i2c_send(I3CBus *bus, uint8_t data) {
> +    trace_legacy_i2c_send(data);
> +    return i2c_send(bus->i2c_bus, data); }
> +
> +int legacy_i2c_start_transfer(I3CBus *bus, uint8_t address, bool
> +is_recv) {
> +    trace_legacy_i2c_start_transfer(address, is_recv);
> +    return i2c_start_transfer(bus->i2c_bus, address, is_recv); }
> +
> +int legacy_i2c_start_recv(I3CBus *bus, uint8_t address) {
> +    trace_legacy_i2c_start_transfer(address, true);
> +    return i2c_start_transfer(bus->i2c_bus, address, /*is_recv=*/true);
> +}
> +
> +int legacy_i2c_start_send(I3CBus *bus, uint8_t address) {
> +    trace_legacy_i2c_start_transfer(address, false);
> +    return i2c_start_transfer(bus->i2c_bus, address,
> +/*is_recv=*/false); }
> +
> +void legacy_i2c_end_transfer(I3CBus *bus) {
> +    trace_legacy_i2c_end_transfer();
> +    i2c_end_transfer(bus->i2c_bus);
> +}
> +
> +I2CSlave *legacy_i2c_device_create_simple(I3CBus *bus, const char *name,
> +                                          uint8_t addr) {
> +    I2CSlave *dev = i2c_slave_new(name, addr);
> +
> +    i2c_slave_realize_and_unref(dev, bus->i2c_bus, &error_abort);
> +    return dev;
> +}
> +
> +static void i3c_target_class_init(ObjectClass *klass, const void *data)
> +{
> +    DeviceClass *k = DEVICE_CLASS(klass);
> +    I3CTargetClass *sc = I3C_TARGET_CLASS(klass);
> +    set_bit(DEVICE_CATEGORY_MISC, k->categories);
> +    k->bus_type = TYPE_I3C_BUS;
> +    device_class_set_props(k, i3c_props);
> +    sc->target_match = i3c_target_match; }
> +
> +static const TypeInfo i3c_target_type_info = {
> +    .name = TYPE_I3C_TARGET,
> +    .parent = TYPE_DEVICE,
> +    .instance_size = sizeof(I3CTarget),
> +    .abstract = true,
> +    .class_size = sizeof(I3CTargetClass),
> +    .class_init = i3c_target_class_init, };
> +
> +static void i3c_register_types(void)
> +{
> +    type_register_static(&i3c_bus_info);
> +    type_register_static(&i3c_target_type_info);
> +}
> +
> +type_init(i3c_register_types)
> diff --git a/hw/i3c/meson.build b/hw/i3c/meson.build index
> ebf20325cb..fb127613fe 100644
> --- a/hw/i3c/meson.build
> +++ b/hw/i3c/meson.build
> @@ -1,3 +1,4 @@
>  i3c_ss = ss.source_set()
> +i3c_ss.add(when: 'CONFIG_I3C', if_true: files('core.c'))
>  i3c_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files('aspeed_i3c.c'))
>  system_ss.add_all(when: 'CONFIG_I3C', if_true: i3c_ss) diff --git
> a/hw/i3c/trace-events b/hw/i3c/trace-events index 3ead84eb45..cdf7cb07f6
> 100644
> --- a/hw/i3c/trace-events
> +++ b/hw/i3c/trace-events
> @@ -5,3 +5,19 @@ aspeed_i3c_read(uint64_t offset, uint64_t data) "I3C read:
> offset 0x%" PRIx64 "
>  aspeed_i3c_write(uint64_t offset, uint64_t data) "I3C write: offset 0x%"
> PRIx64 " data 0x%" PRIx64  aspeed_i3c_device_read(uint32_t deviceid,
> uint64_t offset, uint64_t data) "I3C Dev[%u] read: offset 0x%" PRIx64 " data
> 0x%" PRIx64  aspeed_i3c_device_write(uint32_t deviceid, uint64_t offset,
> uint64_t data) "I3C Dev[%u] write: offset 0x%" PRIx64 " data 0x%" PRIx64
> +
> +# core.c
> +i3c_target_event(uint8_t address, uint8_t event) "I3C target 0x%" PRIx8
> +" event 0x%" PRIx8 i3c_target_handle_ccc(uint8_t address, uint8_t ccc)
> +"I3C target 0x%" PRIx8 " handling CCC 0x%" PRIx8 i3c_target_send_ibi(uint8_t
> address, bool is_recv) "I3C target IBI address 0x%" PRIx8 " RnW=%d"
> +i3c_target_send_ibi_bytes(uint8_t byte) "I3C target IBI byte 0x%" PRIx8
> +i3c_target_ibi_finish(void) "I3C target IBI finish"
> +i3c_start_transfer(uint8_t address, bool is_recv) "I3C START with address 
> 0x%"
> PRIx8 " is_recv=%d"
> +i3c_end_transfer(void) "I3C transfer done"
> +i3c_send(uint32_t num_sent, uint32_t num_to_send, bool ack) "I3C send %"
> PRId32 "/%" PRId32 " bytes, ack=%d"
> +i3c_recv(uint32_t num_read, uint32_t num_to_read, bool ack) "I3C recv %"
> PRId32 "/%" PRId32 " bytes, ack=%d"
> +legacy_i2c_nack(void) "Legacy I2C NACK"
> +legacy_i2c_recv(uint8_t byte) "Legacy I2C recv 0x%" PRIx8
> +legacy_i2c_send(uint8_t byte) "Legacy I2C send 0x%" PRIx8
> +legacy_i2c_start_transfer(uint8_t address, bool is_recv) "Legacy I2C START
> with address 0x%" PRIx8 " is_recv=%d"
> +legacy_i2c_end_transfer(void) "Legacy I2C STOP"
> diff --git a/include/hw/i3c/i3c.h b/include/hw/i3c/i3c.h new file mode 100644
> index 0000000000..cd54223845
> --- /dev/null
> +++ b/include/hw/i3c/i3c.h
> @@ -0,0 +1,277 @@
> +/*
> + * QEMU I3C bus interface.
> + *
> + * Copyright 2025 Google LLC
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later  */
> +
> +#ifndef QEMU_INCLUDE_HW_I3C_I3C_H_
> +#define QEMU_INCLUDE_HW_I3C_I3C_H_
> +
> +#include "hw/qdev-core.h"
> +#include "qom/object.h"
> +#include "hw/i2c/i2c.h"
> +
> +#define TYPE_I3C_TARGET "i3c-target"
> +OBJECT_DECLARE_TYPE(I3CTarget, I3CTargetClass, I3C_TARGET)
> +
> +typedef enum I3CEvent {
> +    I3C_START_RECV,
> +    I3C_START_SEND,
> +    I3C_STOP,
> +    I3C_NACK,
> +} I3CEvent;
> +
> +typedef enum I3CCCC {
> +    /* Broadcast CCCs */
> +    I3C_CCC_ENEC      = 0x00,
> +    I3C_CCC_DISEC     = 0x01,
> +    I3C_CCC_ENTAS0    = 0x02,
> +    I3C_CCC_ENTAS1    = 0x03,
> +    I3C_CCC_ENTAS2    = 0x04,
> +    I3C_CCC_ENTAS3    = 0x05,
> +    I3C_CCC_RSTDAA    = 0x06,
> +    I3C_CCC_ENTDAA    = 0x07,
> +    I3C_CCC_DEFTGTS   = 0x08,
> +    I3C_CCC_SETMWL    = 0x09,
> +    I3C_CCC_SETMRL    = 0x0a,
> +    I3C_CCC_ENTTM     = 0x0b,
> +    I3C_CCC_SETBUSCON = 0x0c,
> +    I3C_CCC_ENDXFER   = 0x12,
> +    I3C_CCC_ENTHDR0   = 0x20,
> +    I3C_CCC_ENTHDR1   = 0x21,
> +    I3C_CCC_ENTHDR2   = 0x22,
> +    I3C_CCC_ENTHDR3   = 0x23,
> +    I3C_CCC_ENTHDR4   = 0x24,
> +    I3C_CCC_ENTHDR5   = 0x25,
> +    I3C_CCC_ENTHDR6   = 0x26,
> +    I3C_CCC_ENTHDR7   = 0x27,
> +    I3C_CCC_SETXTIME  = 0x28,
> +    I3C_CCC_SETAASA   = 0x29,
> +    I3C_CCC_RSTACT    = 0x2a,
> +    I3C_CCC_DEFGRPA   = 0x2b,
> +    I3C_CCC_RSTGRPA   = 0x2c,
> +    I3C_CCC_MLANE     = 0x2d,
> +    /* Direct CCCs */
> +    I3C_CCCD_ENEC       = 0x80,
> +    I3C_CCCD_DISEC      = 0x81,
> +    I3C_CCCD_ENTAS0     = 0x82,
> +    I3C_CCCD_ENTAS1     = 0x83,
> +    I3C_CCCD_ENTAS2     = 0x84,
> +    I3C_CCCD_ENTAS3     = 0x85,
> +    I3C_CCCD_SETDASA    = 0x87,
> +    I3C_CCCD_SETNEWDA   = 0x88,
> +    I3C_CCCD_SETMWL     = 0x89,
> +    I3C_CCCD_SETMRL     = 0x8a,
> +    I3C_CCCD_GETMWL     = 0x8b,
> +    I3C_CCCD_GETMRL     = 0x8c,
> +    I3C_CCCD_GETPID     = 0x8d,
> +    I3C_CCCD_GETBCR     = 0x8e,
> +    I3C_CCCD_GETDCR     = 0x8f,
> +    I3C_CCCD_GETSTATUS  = 0x90,
> +    I3C_CCCD_GETACCCR   = 0x91,
> +    I3C_CCCD_ENDXFER    = 0x92,
> +    I3C_CCCD_SETBRGTGT  = 0x93,
> +    I3C_CCCD_GETMXDS    = 0x94,
> +    I3C_CCCD_GETCAPS    = 0x95,
> +    I3C_CCCD_SETROUTE   = 0x96,
> +    I3C_CCCD_SETXTIME   = 0x98,
> +    I3C_CCCD_GETXTIME   = 0x99,
> +    I3C_CCCD_RSTACT     = 0x9a,
> +    I3C_CCCD_SETGRPA    = 0x9b,
> +    I3C_CCCD_RSTGRPA    = 0x9c,
> +    I3C_CCCD_MLANE      = 0x9d,
> +} I3CCCC;
> +
> +#define CCC_IS_DIRECT(_ccc) (_ccc & 0x80)
> +
> +#define I3C_BROADCAST 0x7e
> +#define I3C_HJ_ADDR 0x02
> +#define I3C_ENTDAA_SIZE 8
> +
> +struct I3CTargetClass {
> +    DeviceClass parent;
> +
> +    /*
> +     * Controller to target. Returns 0 for success, non-zero for NAK or other
> +     * error.
> +     */
> +    int (*send)(I3CTarget *s, const uint8_t *data, uint32_t num_to_send,
> +                uint32_t *num_sent);
> +    /*
> +     * Target to controller. I3C targets are able to terminate reads early, 
> so
> +     * this returns the number of bytes read from the target.
> +     */
> +    uint32_t (*recv)(I3CTarget *s, uint8_t *data, uint32_t num_to_read);
> +    /* Notify the target of a bus state change. */
> +    int (*event)(I3CTarget *s, enum I3CEvent event);
> +    /*
> +     * Handle a read CCC transmitted from a controller.
> +     * CCCs are I3C commands that I3C targets support.
> +     * The target can NACK the CCC if it does not support it.
> +     */
> +    int (*handle_ccc_read)(I3CTarget *s, uint8_t *data, uint32_t
> num_to_read,
> +                           uint32_t *num_read);
> +    /*
> +     * Handle a write CCC transmitted from a controller.
> +     * CCCs are I3C commands that I3C targets support.
> +     * The target can NACK the CCC if it does not support it.
> +     */
> +    int (*handle_ccc_write)(I3CTarget *s, const uint8_t *data,
> +                            uint32_t num_to_send, uint32_t
> *num_sent);
> +
> +    /*
> +     * Matches and adds the candidate if the address matches the
> candidate's
> +     * address.
> +     * Returns true if the address matched, or if this was a broadcast, and
> +     * updates the device list. Otherwise returns false.
> +     */
> +    bool (*target_match)(I3CTarget *candidate, uint8_t address, bool
> is_read,
> +                         bool broadcast, bool in_entdaa); };
> +
> +struct I3CTarget {
> +    DeviceState qdev;
> +
> +    uint8_t address;
> +    uint8_t static_address;
> +    uint8_t dcr;
> +    uint8_t bcr;
> +    uint64_t pid;
> +
> +    /* CCC State tracking. */
> +    I3CCCC curr_ccc;
> +    uint8_t ccc_byte_offset;
> +    bool in_ccc;
> +    bool in_test_mode;
> +};
> +
> +struct I3CNode {
> +    I3CTarget *target;
> +    QLIST_ENTRY(I3CNode) next;
> +};
> +
> +typedef struct I3CNode I3CNode;
> +
> +typedef QLIST_HEAD(I3CNodeList, I3CNode) I3CNodeList;
> +
> +#define TYPE_I3C_BUS "i3c-bus"
> +OBJECT_DECLARE_TYPE(I3CBus, I3CBusClass, I3C_BUS)
> +
> +struct I3CBus {
> +    BusState qbus;
> +
> +    /* Legacy I2C. */
> +    I2CBus *i2c_bus;
> +
> +    I3CNodeList current_devs;
> +    bool broadcast;
> +    uint8_t ccc;
> +    bool in_ccc;
> +    bool in_entdaa;
> +    uint8_t saved_address;
> +};
> +
> +struct I3CBusClass {
> +    DeviceClass parent;
> +
> +    /* Handle an incoming IBI request from a target */
> +    int (*ibi_handle) (I3CBus *bus, uint8_t addr, bool is_recv);
> +    /* Receive data from an IBI request */
> +    int (*ibi_recv) (I3CBus *bus, uint8_t data);
> +    /* Do anything that needs to be done, since the IBI is finished. */
> +    int (*ibi_finish) (I3CBus *bus);
> +};
> +
> +I3CBus *i3c_init_bus(DeviceState *parent, const char *name); I3CBus
> +*i3c_init_bus_type(const char *type, DeviceState *parent,
> +                          const char *name); void
> +i3c_set_target_address(I3CTarget *dev, uint8_t address); bool
> +i3c_bus_busy(I3CBus *bus);
> +
> +/*
> + * Start a transfer on an I3C bus.
> + * If is_recv is known at compile-time (i.e. a device will always be
> +sending or
> + * will always be receiving at a certain point), prefer to use
> +i3c_start_recv or
> + * i3c_start_send instead.
> + *
> + * Returns 0 on success, non-zero on an error.
> + */
> +int i3c_start_transfer(I3CBus *bus, uint8_t address, bool is_recv);
> +
> +/*
> + * Start a receive transfer on an I3C bus.
> + *
> + * Returns 0 on success, non-zero on an error  */ int
> +i3c_start_recv(I3CBus *bus, uint8_t address);
> +
> +/*
> + * Start a send transfer on an I3C bus.
> + *
> + * Returns 0 on success, non-zero on an error  */ int
> +i3c_start_send(I3CBus *bus, uint8_t address);
> +
> +void i3c_end_transfer(I3CBus *bus);
> +void i3c_nack(I3CBus *bus);
> +int i3c_send_byte(I3CBus *bus, uint8_t data); int i3c_send(I3CBus *bus,
> +const uint8_t *data, uint32_t num_to_send,
> +             uint32_t *num_sent);
> +/*
> + * I3C receives can only NACK on a CCC. The target should NACK a CCC it
> +does not
> + * support.
> + */
> +int i3c_recv_byte(I3CBus *bus, uint8_t *data); int i3c_recv(I3CBus
> +*bus, uint8_t *data, uint32_t num_to_read,
> +             uint32_t *num_read);
> +bool i3c_scan_bus(I3CBus *bus, uint8_t address, enum I3CEvent event);
> +int i3c_do_entdaa(I3CBus *bus, uint8_t address, uint64_t *pid, uint8_t *bcr,
> +                  uint8_t *dcr);
> +int i3c_start_device_transfer(I3CTarget *dev, int send_length); bool
> +i3c_target_match_and_add(I3CBus *bus, I3CTarget *target, uint8_t address,
> +                             enum I3CEvent event); int
> +i3c_target_send_ibi(I3CTarget *t, uint8_t addr, bool is_recv); int
> +i3c_target_send_ibi_bytes(I3CTarget *t, uint8_t data); int
> +i3c_target_ibi_finish(I3CTarget *t, uint8_t data);
> +
> +/*
> + * Legacy I2C functions.
> + *
> + * These are wrapper for I2C functions that take in an I3C bus instead
> +of an I2C
> + * bus. Internally they use the I2C bus (and devices attached to it)
> +that's a
> + * part of the I3C bus
> + */
> +void legacy_i2c_nack(I3CBus *bus);
> +uint8_t legacy_i2c_recv(I3CBus *bus);
> +int legacy_i2c_send(I3CBus *bus, uint8_t data); int
> +legacy_i2c_start_transfer(I3CBus *bus, uint8_t address, bool is_recv);
> +int legacy_i2c_start_recv(I3CBus *bus, uint8_t address); int
> +legacy_i2c_start_send(I3CBus *bus, uint8_t address); void
> +legacy_i2c_end_transfer(I3CBus *bus); I2CSlave
> +*legacy_i2c_device_create_simple(I3CBus *bus, const char *name,
> +                                          uint8_t addr);
> +
> +/**
> + * Create an I3C Target.
> + *
> + * The target returned from this function still needs to be realized.
> + */
> +I3CTarget *i3c_target_new(const char *name, uint8_t addr, uint8_t dcr,
> +                          uint8_t bcr, uint64_t pid);
> +
> +/**
> + * Create and realize an I3C target.
> + *
> + * Create the target, initialize it, put it on the specified I3C bus,
> +and
> + * realize it.
> + */
> +I3CTarget *i3c_target_create_simple(I3CBus *bus, const char *name,
> +                                    uint8_t addr, uint8_t dcr, uint8_t
> bcr,
> +                                    uint64_t pid);
> +
> +/* Realize and drop the reference count on an I3C target. */ bool
> +i3c_target_realize_and_unref(I3CTarget *dev, I3CBus *bus, Error
> +**errp);
> +
> +#endif  /* QEMU_INCLUDE_HW_I3C_I3C_H_ */
> --
> 2.50.0.rc1.591.g9c95f17f64-goog

Reviewed-by: Jamin Lin <[email protected]>

Thanks,
Jamin

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