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4 .\" Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
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34 .Nd driver for LTC4305 and LTC4306 I2C mux chips
36 To compile this driver into the kernel,
37 place the following line in your
38 kernel configuration file:
39 .Bd -ragged -offset indent
43 Alternatively, to load the driver as a
44 module at boot time, place the following line in
46 .Bd -literal -offset indent
52 driver supports the LTC4305 and LTC4306 I2C bus multiplexer (mux) chips.
53 It automatically connects an upstream I2C bus to one of several downstream
54 buses as needed when slave devices on the downstream buses initiate I/O.
55 More information on the automatic switching behavior is available in
62 device node is defined as a child node of its upstream i2c bus.
65 node are additional i2c buses, which will have their own i2c slave
66 devices described in their child nodes.
70 driver conforms to the standard
72 .Li i2c/i2c-mux-ltc4306.txt
74 bindings document, except that the following optional properties
75 are not currently supported and will be ignored if present:
76 .Bl -bullet -compact -inset -offset indent
84 ltc,downstream-accelerators-enable
86 ltc,upstream-accelerators-enable
88 .Sh HINTS CONFIGURATION
91 based system, these values are configurable for
93 .Bl -tag -width indent
94 .It Va hint.ltc430x.<unit>.at
99 instance is attached to.
102 When configured via hints, the driver automatically adds an iicbus
103 instance for every downstream bus supported by the chip.
104 There is currently no way to indicate used versus unused channels.
111 driver first appeared in