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When the adapter name is used as a parameter, some adapters share the same name. For instance, both /dev/i2c-0 and /dev/i2c-1 have the bus name "xxxx". This leads to only the first found I2C adapter being opened. To increase flexibility, accept both the I2C master's name and number as parameters and parse accordingly. Signed-off-by: Wei Liu <quic_wliu8@quicinc.com>
86 lines
2.4 KiB
Markdown
86 lines
2.4 KiB
Markdown
# vhost-device-i2c - I2C emulation backend daemon
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## Description
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This program is a vhost-user backend that emulates a VirtIO I2C bus.
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This program takes the layout of the i2c bus and its devices on the host
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OS and then talks to them via the /dev/i2c-X interface when a request
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comes from the guest OS for an I2C or SMBUS device.
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This program is tested with QEMU's `-device vhost-user-i2c-pci` but should
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work with any virtual machine monitor (VMM) that supports vhost-user. See the
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Examples section below.
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## Synopsis
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**vhost-device-i2c** [*OPTIONS*]
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## Options
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.. program:: vhost-device-i2c
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.. option:: -h, --help
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Print help.
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.. option:: -s, --socket-path=PATH
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Location of vhost-user Unix domain sockets, this path will be suffixed with
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0,1,2..socket_count-1.
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.. option:: -c, --socket-count=INT
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Number of guests (sockets) to attach to, default set to 1.
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.. option:: -l, --device-list=I2C-DEVICES
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I2c device list at the host OS can be in two different format, name and number:
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- format by name:
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\<bus-name>:<client_addr>[:<client_addr>],[\<bus-name>:<client_addr>[:<client_addr>]]
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```
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Example: --device-list "i915 gmbus dpd:32:21,DPDDC-D:10:23"
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```
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Here,
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bus-name: is adatper's name. e.g. value of /sys/bus/i2c/devices/i2c-0/name.
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client_addr (decimal): address for client device, 32 == 0x20.
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- format by number:
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\<bus>:<client_addr>[:<client_addr>],[\<bus>:<client_addr>[:<client_addr>]]
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```
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Example: --device-list "2:32:21,3:10:23"
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```
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Here,
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bus (decimal): adatper bus number. e.g. 2 for /dev/i2c-2, 3 for /dev/i2c-3.
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client_addr (decimal): address for client device, 32 == 0x20.
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## Examples
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The daemon should be started first:
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::
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host# vhost-device-i2c --socket-path=vi2c.sock --socket-count=1 --device-list "i915 gmbus dpd:32"
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host# vhost-device-i2c --socket-path=vi2c.sock --socket-count=1 --device-list "0:32"
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The QEMU invocation needs to create a chardev socket the device can
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use to communicate as well as share the guests memory over a memfd.
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::
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host# qemu-system \
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-chardev socket,path=vi2c.sock,id=vi2c \
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-device vhost-user-i2c-pci,chardev=vi2c,id=i2c \
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-m 4096 \
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-object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on \
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-numa node,memdev=mem \
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...
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## License
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This project is licensed under either of
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- [Apache License](http://www.apache.org/licenses/LICENSE-2.0), Version 2.0
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- [BSD-3-Clause License](https://opensource.org/licenses/BSD-3-Clause)
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