vhost-device/i2c
Viresh Kumar 677b897576 i2c: Move i2c to top folder
The workspace section in Rust documentation suggests adding new crates
in the top level directory itself instead of the src folder. Remove the
top level src folder.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2022-01-05 11:09:33 +05:30
..
src i2c: Move i2c to top folder 2022-01-05 11:09:33 +05:30
Cargo.toml i2c: Move i2c to top folder 2022-01-05 11:09:33 +05:30
README.md i2c: Move i2c to top folder 2022-01-05 11:09:33 +05:30

vhost-device-i2c - I2C emulation backend daemon

Description

This program is a vhost-user backend that emulates a VirtIO I2C bus. This program takes the layout of the i2c bus and its devices on the host OS and then talks to them via the /dev/i2c-X interface when a request comes from the guest OS for an I2C or SMBUS device.

This program is tested with QEMU's -device vhost-user-i2c-pci but should work with any virtual machine monitor (VMM) that supports vhost-user. See the Examples section below.

Synopsis

vhost-device-i2c [OPTIONS]

Options

.. program:: vhost-device-i2c

.. option:: -h, --help

Print help.

.. option:: -s, --socket-path=PATH

Location of vhost-user Unix domain sockets, this path will be suffixed with 0,1,2..socket_count-1.

.. option:: -c, --socket-count=INT

Number of guests (sockets) to attach to, default set to 1.

.. option:: -l, --device-list=I2C-DEVICES

I2c device list at the host OS in the format: :<client_addr>[:<client_addr>],[:<client_addr>[:<client_addr>]]

  Example: --device-list "2:32:21,3:10:23"

Here, bus (decimal): adatper bus number. e.g. 2 for /dev/i2c-2, 3 for /dev/i2c-3. client_addr (decimal): address for client device, 32 == 0x20.

Examples

The daemon should be started first:

::

host# vhost-device-i2c --socket-path=vi2c.sock --socket-count=1 --device-list 0:32

The QEMU invocation needs to create a chardev socket the device can use to communicate as well as share the guests memory over a memfd.

::

host# qemu-system
-chardev socket,path=vi2c.sock,id=vi2c
-device vhost-user-i2c-pci,chardev=vi2c,id=i2c
-m 4096
-object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on
-numa node,memdev=mem
...