> Subject: [PATCH 17/19] hw/i3c: Add Mock target
> 
> Adds a simple i3c device to be used for testing in lieu of a real device.
> 
> The mock target supports the following features:
> - A buffer that users can read and write to.
> - CCC support for commonly used CCCs when probing devices on an I3C bus.
> - IBI sending upon receiving a user-defined byte.
> 
> Signed-off-by: Joe Komlodi <[email protected]>
> 
> Reviewed-by: Titus Rwantare <[email protected]>
> Reviewed-by: Patrick Venture <[email protected]>
> ---
>  hw/i3c/Kconfig                   |  10 +
>  hw/i3c/meson.build               |   1 +
>  hw/i3c/mock-i3c-target.c         | 311
> +++++++++++++++++++++++++++++++
>  hw/i3c/trace-events              |   9 +
>  include/hw/i3c/mock-i3c-target.h |  52 ++++++
>  5 files changed, 383 insertions(+)
>  create mode 100644 hw/i3c/mock-i3c-target.c  create mode 100644
> include/hw/i3c/mock-i3c-target.h
> 
> diff --git a/hw/i3c/Kconfig b/hw/i3c/Kconfig index ecec77d6fc..d5c6d4049b
> 100644
> --- a/hw/i3c/Kconfig
> +++ b/hw/i3c/Kconfig
> @@ -3,3 +3,13 @@ config I3C
> 
>  config DW_I3C
>      bool
> +
> +config I3C_DEVICES
> +    # Device group for i3c devices which can reasonably be user-plugged to
> any
> +    # board's i3c bus.
> +    bool
> +
> +config MOCK_I3C_TARGET
> +    bool
> +    select I3C
> +    default y if I3C_DEVICES
> diff --git a/hw/i3c/meson.build b/hw/i3c/meson.build index
> 83d75e7d5c..e614b18712 100644
> --- a/hw/i3c/meson.build
> +++ b/hw/i3c/meson.build
> @@ -2,4 +2,5 @@ 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'))
>  i3c_ss.add(when: 'CONFIG_DW_I3C', if_true: files('dw-i3c.c'))
> +i3c_ss.add(when: 'CONFIG_MOCK_I3C_TARGET', if_true:
> +files('mock-i3c-target.c'))
>  system_ss.add_all(when: 'CONFIG_I3C', if_true: i3c_ss) diff --git
> a/hw/i3c/mock-i3c-target.c b/hw/i3c/mock-i3c-target.c new file mode 100644
> index 0000000000..8d42776ece
> --- /dev/null
> +++ b/hw/i3c/mock-i3c-target.c
> @@ -0,0 +1,311 @@
> +/*
> + * Mock I3C Device
> + *
> + * Copyright (c) 2025 Google LLC
> + *
> + * The mock I3C device can be thought of as a simple EEPROM. It has a
> +buffer,
> + * and the pointer in the buffer is reset to 0 on an I3C STOP.
> + * To write to the buffer, issue a private write and send data.
> + * To read from the buffer, issue a private read.
> + *
> + * The mock target also supports sending target interrupt IBIs.
> + * To issue an IBI, set the 'ibi-magic-num' property to a non-zero
> +number, and
> + * send that number in a private transaction. The mock target will
> +issue an IBI
> + * after 1 second.
> + *
> + * It also supports a handful of CCCs that are typically used when
> +probing I3C
> + * devices.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later  */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/log.h"
> +#include "trace.h"
> +#include "hw/i3c/i3c.h"
> +#include "hw/i3c/mock-i3c-target.h"
> +#include "hw/irq.h"
> +#include "hw/qdev-properties.h"
> +#include "qapi/error.h"
> +#include "qemu/module.h"
> +
> +#ifndef MOCK_I3C_TARGET_DEBUG
> +#define MOCK_I3C_TARGET_DEBUG 0
> +#endif
> +
> +#define DB_PRINTF(...) do { \
> +        if (MOCK_I3C_TARGET_DEBUG) { \
> +            qemu_log("%s: ", __func__); \
> +            qemu_log(__VA_ARGS__); \
> +        } \
> +    } while (0)
> +
> +#define IBI_DELAY_NS (1 * 1000 * 1000)
> +
> +static uint32_t mock_i3c_target_rx(I3CTarget *i3c, uint8_t *data,
> +                                   uint32_t num_to_read) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(i3c);
> +    uint32_t i;
> +
> +    /* Bounds check. */
> +    if (s->p_buf == s->cfg.buf_size) {
> +        return 0;
> +    }
> +
> +    for (i = 0; i < num_to_read; i++) {
> +        data[i] = s->buf[s->p_buf];
> +        trace_mock_i3c_target_rx(data[i]);
> +        s->p_buf++;
> +        if (s->p_buf == s->cfg.buf_size) {
> +            break;
> +        }
> +    }
> +
> +    /* Return the number of bytes we're sending to the controller. */
> +    return i;
> +}
> +
> +static void mock_i3c_target_ibi_timer_start(MockI3cTargetState *s) {
> +    int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> +    timer_mod(&s->qtimer, now + IBI_DELAY_NS); }
> +
> +static int mock_i3c_target_tx(I3CTarget *i3c, const uint8_t *data,
> +                              uint32_t num_to_send, uint32_t
> *num_sent)
> +{
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(i3c);
> +    int ret;
> +    uint32_t to_write;
> +
> +    if (s->cfg.ibi_magic && num_to_send == 1 && s->cfg.ibi_magic == *data)
> {
> +        mock_i3c_target_ibi_timer_start(s);
> +        return 0;
> +    }
> +
> +    /* Bounds check. */
> +    if (num_to_send + s->p_buf > s->cfg.buf_size) {
> +        to_write = s->cfg.buf_size - s->p_buf;
> +        ret = -1;
> +    } else {
> +        to_write = num_to_send;
> +        ret = 0;
> +    }
> +    for (uint32_t i = 0; i < to_write; i++) {
> +        trace_mock_i3c_target_tx(data[i]);
> +        s->buf[s->p_buf] = data[i];
> +        s->p_buf++;
> +    }
> +    return ret;
> +}
> +
> +static int mock_i3c_target_event(I3CTarget *i3c, enum I3CEvent event) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(i3c);
> +
> +    trace_mock_i3c_target_event(event);
> +    if (event == I3C_STOP) {
> +        s->in_ccc = false;
> +        s->curr_ccc = 0;
> +        s->ccc_byte_offset = 0;
> +        s->p_buf = 0;
> +    }
> +
> +    return 0;
> +}
> +
> +static int mock_i3c_target_handle_ccc_read(I3CTarget *i3c, uint8_t *data,
> +                                           uint32_t num_to_read,
> +                                           uint32_t *num_read) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(i3c);
> +
> +    switch (s->curr_ccc) {
> +    case I3C_CCCD_GETMXDS:
> +        /* Default data rate for I3C. */
> +        while (s->ccc_byte_offset < num_to_read) {
> +            if (s->ccc_byte_offset >= 2) {
> +                break;
> +            }
> +            data[s->ccc_byte_offset] = 0;
> +            *num_read = s->ccc_byte_offset;
> +            s->ccc_byte_offset++;
> +        }
> +        break;
> +    case I3C_CCCD_GETCAPS:
> +        /* Support I3C version 1.1.x, no other features. */
> +        while (s->ccc_byte_offset < num_to_read) {
> +            if (s->ccc_byte_offset >= 2) {
> +                break;
> +            }
> +            if (s->ccc_byte_offset == 0) {
> +                data[s->ccc_byte_offset] = 0;
> +            } else {
> +                data[s->ccc_byte_offset] = 0x01;
> +            }
> +            *num_read = s->ccc_byte_offset;
> +            s->ccc_byte_offset++;
> +        }
> +        break;
> +    case I3C_CCCD_GETMWL:
> +    case I3C_CCCD_GETMRL:
> +        /* MWL/MRL is MSB first. */
> +        while (s->ccc_byte_offset < num_to_read) {
> +            if (s->ccc_byte_offset >= 2) {
> +                break;
> +            }
> +            data[s->ccc_byte_offset] = (s->cfg.buf_size &
> +                                        (0xff00 >>
> (s->ccc_byte_offset * 8))) >>
> +                                        (8 - (s->ccc_byte_offset *
> 8));
> +            s->ccc_byte_offset++;
> +            *num_read = num_to_read;
> +        }
> +        break;
> +    case I3C_CCC_ENTDAA:
> +    case I3C_CCCD_GETPID:
> +    case I3C_CCCD_GETBCR:
> +    case I3C_CCCD_GETDCR:
> +        /* Nothing to do. */
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "Unhandled CCC 0x%.2x\n",
> s->curr_ccc);
> +        return -1;
> +    }
> +
> +    trace_mock_i3c_target_handle_ccc_read(*num_read, num_to_read);
> +    return 0;
> +}
> +
> +static int mock_i3c_target_handle_ccc_write(I3CTarget *i3c, const uint8_t
> *data,
> +                                            uint32_t num_to_send,
> +                                            uint32_t *num_sent) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(i3c);
> +
> +    if (!s->curr_ccc) {
> +        s->in_ccc = true;
> +        s->curr_ccc = *data;
> +        trace_mock_i3c_target_new_ccc(s->curr_ccc);
> +    }
> +
> +    *num_sent = 1;
> +    switch (s->curr_ccc) {
> +    case I3C_CCC_ENEC:
> +    case I3C_CCCD_ENEC:
> +        s->can_ibi = true;
> +        break;
> +    case I3C_CCC_DISEC:
> +    case I3C_CCCD_DISEC:
> +        s->can_ibi = false;
> +        break;
> +    case I3C_CCC_ENTDAA:
> +    case I3C_CCC_SETAASA:
> +    case I3C_CCC_RSTDAA:
> +    case I3C_CCCD_SETDASA:
> +    case I3C_CCCD_GETPID:
> +    case I3C_CCCD_GETBCR:
> +    case I3C_CCCD_GETDCR:
> +    case I3C_CCCD_GETMWL:
> +    case I3C_CCCD_GETMRL:
> +    case I3C_CCCD_GETMXDS:
> +    case I3C_CCCD_GETCAPS:
> +        /* Nothing to do. */
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "Unhandled CCC 0x%.2x\n",
> s->curr_ccc);
> +        return -1;
> +    }
> +
> +    trace_mock_i3c_target_handle_ccc_write(*num_sent, num_to_send);
> +    return 0;
> +}
> +
> +static void mock_i3c_target_do_ibi(MockI3cTargetState *s) {
> +    if (!s->can_ibi) {
> +        DB_PRINTF("IBIs disabled by controller");
> +        return;
> +    }
> +
> +    trace_mock_i3c_target_do_ibi(s->i3c.address, true);
> +    int nack = i3c_target_send_ibi(&s->i3c, s->i3c.address, 
> /*is_recv=*/true);
> +    /* Getting NACKed isn't necessarily an error, just print it out. */
> +    if (nack) {
> +        DB_PRINTF("NACKed from controller when sending target
> interrupt.\n");
> +    }
> +    nack = i3c_target_ibi_finish(&s->i3c, 0x00);
> +    if (nack) {
> +        DB_PRINTF("NACKed from controller when finishing target
> interrupt.\n");
> +    }
> +}
> +
> +static void mock_i3c_target_timer_elapsed(void *opaque) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(opaque);
> +    timer_del(&s->qtimer);
> +    mock_i3c_target_do_ibi(s);
> +}
> +
> +static void mock_i3c_target_reset(I3CTarget *i3c) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(i3c);
> +    s->can_ibi = false;
> +}
> +
> +static void mock_i3c_target_realize(DeviceState *dev, Error **errp) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(dev);
> +    s->buf = g_new0(uint8_t, s->cfg.buf_size);
> +    mock_i3c_target_reset(&s->i3c);
> +}
> +
> +static void mock_i3c_target_init(Object *obj) {
> +    MockI3cTargetState *s = MOCK_I3C_TARGET(obj);
> +    s->can_ibi = false;
> +
> +    /* For IBIs. */
> +    timer_init_ns(&s->qtimer, QEMU_CLOCK_VIRTUAL,
> mock_i3c_target_timer_elapsed,
> +                  s);
> +}
> +
> +static const Property remote_i3c_props[] = {
> +    /* The size of the internal buffer. */
> +    DEFINE_PROP_UINT32("buf-size", MockI3cTargetState, cfg.buf_size,
> 0x100),
> +    /*
> +     * If the mock target receives this number, it will issue an IBI after
> +     * 1 second. Disabled if the IBI magic number is 0.
> +     */
> +    DEFINE_PROP_UINT8("ibi-magic-num", MockI3cTargetState,
> +cfg.ibi_magic, 0x00), };
> +
> +static void mock_i3c_target_class_init(ObjectClass *klass, const void
> +*data) {
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    I3CTargetClass *k = I3C_TARGET_CLASS(klass);
> +
> +    dc->realize = mock_i3c_target_realize;
> +    k->event = mock_i3c_target_event;
> +    k->recv = mock_i3c_target_rx;
> +    k->send = mock_i3c_target_tx;
> +    k->handle_ccc_read = mock_i3c_target_handle_ccc_read;
> +    k->handle_ccc_write = mock_i3c_target_handle_ccc_write;
> +
> +    device_class_set_props(dc, remote_i3c_props); }
> +
> +static const TypeInfo mock_i3c_target_info = {
> +    .name          = TYPE_MOCK_I3C_TARGET,
> +    .parent        = TYPE_I3C_TARGET,
> +    .instance_size = sizeof(MockI3cTargetState),
> +    .instance_init = mock_i3c_target_init,
> +    .class_init    = mock_i3c_target_class_init,
> +};
> +
> +static void mock_i3c_target_register_types(void)
> +{
> +    type_register_static(&mock_i3c_target_info);
> +}
> +
> +type_init(mock_i3c_target_register_types)
> diff --git a/hw/i3c/trace-events b/hw/i3c/trace-events index
> 39f33d9a50..3d6dd4f7dd 100644
> --- a/hw/i3c/trace-events
> +++ b/hw/i3c/trace-events
> @@ -36,3 +36,12 @@ 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"
> +
> +# mock-target.c
> +mock_i3c_target_rx(uint8_t byte) "I3C mock target read 0x%" PRIx8
> +mock_i3c_target_tx(uint8_t byte) "I3C mock target write 0x%" PRIx8
> +mock_i3c_target_event(uint8_t event) "I3C mock target event 0x%" PRIx8
> +mock_i3c_target_handle_ccc_read(uint32_t num_read, uint32_t
> num_to_read) "I3C mock target read %" PRId32 "/%" PRId32 " bytes"
> +mock_i3c_target_new_ccc(uint8_t ccc) "I3C mock target handle CCC 0x%"
> +PRIx8 mock_i3c_target_handle_ccc_write(uint32_t num_sent, uint32_t
> num_to_send) "I3C mock target send %" PRId32 "/%" PRId32 " bytes"
> +mock_i3c_target_do_ibi(uint8_t address, bool is_recv) "I3C mock target IBI
> with address 0x%" PRIx8 " RnW=%d"
> diff --git a/include/hw/i3c/mock-i3c-target.h
> b/include/hw/i3c/mock-i3c-target.h
> new file mode 100644
> index 0000000000..7ac55a3179
> --- /dev/null
> +++ b/include/hw/i3c/mock-i3c-target.h
> @@ -0,0 +1,52 @@
> +#ifndef MOCK_I3C_TARGET_H_
> +#define MOCK_I3C_TARGET_H_
> +
> +/*
> + * Mock I3C Device
> + *
> + * Copyright (c) 2025 Google LLC
> + *
> + * The mock I3C device can be thought of as a simple EEPROM. It has a
> +buffer,
> + * and the pointer in the buffer is reset to 0 on an I3C STOP.
> + * To write to the buffer, issue a private write and send data.
> + * To read from the buffer, issue a private read.
> + *
> + * The mock target also supports sending target interrupt IBIs.
> + * To issue an IBI, set the 'ibi-magic-num' property to a non-zero
> +number, and
> + * send that number in a private transaction. The mock target will
> +issue an IBI
> + * after 1 second.
> + *
> + * It also supports a handful of CCCs that are typically used when
> +probing I3C
> + * devices.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later  */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/timer.h"
> +#include "hw/i3c/i3c.h"
> +
> +#define TYPE_MOCK_I3C_TARGET "mock-i3c-target"
> +OBJECT_DECLARE_SIMPLE_TYPE(MockI3cTargetState, MOCK_I3C_TARGET)
> +
> +struct MockI3cTargetState {
> +    I3CTarget i3c;
> +
> +    /* General device state */
> +    bool can_ibi;
> +    QEMUTimer qtimer;
> +    size_t p_buf;
> +    uint8_t *buf;
> +
> +    /* For Handing CCCs. */
> +    bool in_ccc;
> +    I3CCCC curr_ccc;
> +    uint8_t ccc_byte_offset;
> +
> +    struct {
> +        uint32_t buf_size;
> +        uint8_t ibi_magic;
> +    } cfg;
> +};
> +
> +#endif
> --
> 2.50.0.rc1.591.g9c95f17f64-goog

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

Thanks,
Jamin


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