We have implemented I2C and the first GPIO device in Rust for QEMU.
Additionally, in the respective patches, we have shared our insights and
experiences regarding the use of Rust for device modeling within QEMU.

1. The first patch implements the BusState for the I2CBus infrastructure.
2. The second patch implements the I2CBus and I2CSlave infrastructure, along
   with a discussion of the challenges encountered during the implementation.
3. The third patch moves the struct definition of the PCF8574 to the
   corresponding header file.
4. The fourth patch provides a set of necessary helper functions for the PCF8574
   GPIO device.
5. The fifth patch implements the PCF8574 GPIO device, along with a discussion
   of the issues and considerations addressed during the implementation.

Regarding this series of patches, we have found that Rust for QEMU is indeed
still not mature enough and requires continuous iteration. Additionally, the
lack of basic documentation also needs to be addressed. In this regard, I hope
our team(HUST OpenAtom Open Source Club) can contribute to the documentation
efforts for Rust for QEMU.

Link: https://groups.google.com/g/hust-os-kernel-patches/c/z7vHWg3xvDc

Signed-off-by: Chao Liu <chao.liu@openatom.club>
Signed-off-by: Chen Miao <chenmiao@openatom.club>

---
Changes in V2:
  - According to Zhao's suggestions, some modifications were made to the first
    and second patches respectively, such as changing some bus names, adding
    some Safety comments, and adding callbacks for I2CSlave.
  - While we were making changes to the first PATCH, Chao Liu pointed out that
    the realize function was unnecessary in the bus. After discussion, we
    removed the bus::realize function. Since no other components are currently
    using the bus, we added a TODO comment for clarification.

chenmiao (5):
  rust/hw/core: Add the BusState of rust version
  rust/hw/core: Add rust bindings/funcs for i2c bus
  hw/gpio: Move the pcf8574 struct to header
  rust/hw/core: Provide some interfaces for the GPIO device
  rust/hw/gpio: Add the the first gpio device pcf8574

 hw/gpio/Kconfig                      |   5 +
 hw/gpio/meson.build                  |   2 +-
 hw/gpio/pcf8574.c                    |  32 --
 include/hw/gpio/pcf8574.h            |  36 +++
 rust/Cargo.lock                      |  21 +-
 rust/Cargo.toml                      |   1 +
 rust/hw/Kconfig                      |   1 +
 rust/hw/core/meson.build             |   2 +
 rust/hw/core/src/bus.rs              |  44 +++
 rust/hw/core/src/i2c.rs              | 421 +++++++++++++++++++++++++++
 rust/hw/core/src/irq.rs              |   6 +-
 rust/hw/core/src/lib.rs              |   6 +
 rust/hw/core/src/qdev.rs             |  12 +-
 rust/hw/core/wrapper.h               |   1 +
 rust/hw/gpio/Kconfig                 |   2 +
 rust/hw/gpio/meson.build             |   1 +
 rust/hw/gpio/pcf8574/Cargo.toml      |  31 ++
 rust/hw/gpio/pcf8574/build.rs        |   1 +
 rust/hw/gpio/pcf8574/meson.build     |  50 ++++
 rust/hw/gpio/pcf8574/src/bindings.rs |  29 ++
 rust/hw/gpio/pcf8574/src/device.rs   | 180 ++++++++++++
 rust/hw/gpio/pcf8574/src/lib.rs      |   4 +
 rust/hw/gpio/pcf8574/wrapper.h       |  51 ++++
 rust/hw/meson.build                  |   1 +
 24 files changed, 902 insertions(+), 38 deletions(-)
 create mode 100644 rust/hw/core/src/bus.rs
 create mode 100644 rust/hw/core/src/i2c.rs
 create mode 100644 rust/hw/gpio/Kconfig
 create mode 100644 rust/hw/gpio/meson.build
 create mode 100644 rust/hw/gpio/pcf8574/Cargo.toml
 create mode 120000 rust/hw/gpio/pcf8574/build.rs
 create mode 100644 rust/hw/gpio/pcf8574/meson.build
 create mode 100644 rust/hw/gpio/pcf8574/src/bindings.rs
 create mode 100644 rust/hw/gpio/pcf8574/src/device.rs
 create mode 100644 rust/hw/gpio/pcf8574/src/lib.rs
 create mode 100644 rust/hw/gpio/pcf8574/wrapper.h

-- 
2.43.0