mirror of
https://github.com/torvalds/linux.git
synced 2024-11-11 06:31:49 +00:00
usb: typec: Add firmware documentation for the Intel PMC mux control
Adding documentation that describes how the PMC mux-agent function is described in the ACPI tables. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Link: https://lore.kernel.org/r/20200507150900.12102-4-heikki.krogerus@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Heikki Krogerus
Greg Kroah-Hartman
parent
ff4a30d5e2
commit
1f478dc2a1
153
Documentation/firmware-guide/acpi/intel-pmc-mux.rst
Normal file
153
Documentation/firmware-guide/acpi/intel-pmc-mux.rst
Normal file
@ -0,0 +1,153 @@
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
=====================
|
||||
Intel North Mux-Agent
|
||||
=====================
|
||||
|
||||
Introduction
|
||||
============
|
||||
|
||||
North Mux-Agent is a function of the Intel PMC firmware that is supported on
|
||||
most Intel based platforms that have the PMC microcontroller. It's used for
|
||||
configuring the various USB Multiplexer/DeMultiplexers on the system. The
|
||||
platforms that allow the mux-agent to be configured from the operating system
|
||||
have an ACPI device object (node) with HID "INTC105C" that represents it.
|
||||
|
||||
The North Mux-Agent (aka. Intel PMC Mux Control, or just mux-agent) driver
|
||||
communicates with the PMC microcontroller by using the PMC IPC method
|
||||
(drivers/platform/x86/intel_scu_ipc.c). The driver registers with the USB Type-C
|
||||
Mux Class which allows the USB Type-C Controller and Interface drivers to
|
||||
configure the cable plug orientation and mode (with Alternate Modes). The driver
|
||||
also registers with the USB Role Class in order to support both USB Host and
|
||||
Device modes. The driver is located here: drivers/usb/typec/mux/intel_pmc_mux.c.
|
||||
|
||||
Port nodes
|
||||
==========
|
||||
|
||||
General
|
||||
-------
|
||||
|
||||
For every USB Type-C connector under the mux-agent control on the system, there
|
||||
is a separate child node under the PMC mux-agent device node. Those nodes do not
|
||||
represent the actual connectors, but instead the "channels" in the mux-agent
|
||||
that are associated with the connectors::
|
||||
|
||||
Scope (_SB.PCI0.PMC.MUX)
|
||||
{
|
||||
Device (CH0)
|
||||
{
|
||||
Name (_ADR, 0)
|
||||
}
|
||||
|
||||
Device (CH1)
|
||||
{
|
||||
Name (_ADR, 1)
|
||||
}
|
||||
}
|
||||
|
||||
_PLD (Physical Location of Device)
|
||||
----------------------------------
|
||||
|
||||
The optional _PLD object can be used with the port (the channel) nodes. If _PLD
|
||||
is supplied, it should match the connector node _PLD::
|
||||
|
||||
Scope (_SB.PCI0.PMC.MUX)
|
||||
{
|
||||
Device (CH0)
|
||||
{
|
||||
Name (_ADR, 0)
|
||||
Method (_PLD, 0, NotSerialized)
|
||||
{
|
||||
/* Consider this as pseudocode. */
|
||||
Return (\_SB.USBC.CON0._PLD())
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Mux-agent specific _DSD Device Properties
|
||||
-----------------------------------------
|
||||
|
||||
Port Numbers
|
||||
~~~~~~~~~~~~
|
||||
|
||||
In order to configure the muxes behind a USB Type-C connector, the PMC firmware
|
||||
needs to know the USB2 port and the USB3 port that is associated with the
|
||||
connector. The driver extracts the correct port numbers by reading specific _DSD
|
||||
device properties named "usb2-port-number" and "usb3-port-number". These
|
||||
properties have integer value that means the port index. The port index number
|
||||
is 1's based, and value 0 is illegal. The driver uses the numbers extracted from
|
||||
these device properties as-is when sending the mux-agent specific messages to
|
||||
the PMC::
|
||||
|
||||
Name (_DSD, Package () {
|
||||
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||||
Package() {
|
||||
Package () {"usb2-port-number", 6},
|
||||
Package () {"usb3-port-number", 3},
|
||||
},
|
||||
})
|
||||
|
||||
Orientation
|
||||
~~~~~~~~~~~
|
||||
|
||||
Depending on the platform, the data and SBU lines coming from the connector may
|
||||
be "fixed" from the mux-agent's point of view, which means the mux-agent driver
|
||||
should not configure them according to the cable plug orientation. This can
|
||||
happen for example if a retimer on the platform handles the cable plug
|
||||
orientation. The driver uses a specific device properties "sbu-orientation"
|
||||
(SBU) and "hsl-orientation" (data) to know if those lines are "fixed", and to
|
||||
which orientation. The value that these properties have is a string value, and
|
||||
it can be one that is defined for the USB Type-C connector orientation: "normal"
|
||||
or "reversed"::
|
||||
|
||||
Name (_DSD, Package () {
|
||||
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||||
Package() {
|
||||
Package () {"sbu-orientation", "normal"},
|
||||
Package () {"hsl-orientation", "normal"},
|
||||
},
|
||||
})
|
||||
|
||||
Example ASL
|
||||
===========
|
||||
|
||||
The following ASL is an example that shows the mux-agent node, and two
|
||||
connectors under its control::
|
||||
|
||||
Scope (_SB.PCI0.PMC)
|
||||
{
|
||||
Device (MUX)
|
||||
{
|
||||
Name (_HID, "INTC105C")
|
||||
|
||||
Device (CH0)
|
||||
{
|
||||
Name (_ADR, 0)
|
||||
|
||||
Name (_DSD, Package () {
|
||||
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||||
Package() {
|
||||
Package () {"usb2-port-number", 6},
|
||||
Package () {"usb3-port-number", 3},
|
||||
Package () {"sbu-orientation", "normal"},
|
||||
Package () {"hsl-orientation", "normal"},
|
||||
},
|
||||
})
|
||||
}
|
||||
|
||||
Device (CH1)
|
||||
{
|
||||
Name (_ADR, 1)
|
||||
|
||||
Name (_DSD, Package () {
|
||||
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||||
Package() {
|
||||
Package () {"usb2-port-number", 5},
|
||||
Package () {"usb3-port-number", 2},
|
||||
Package () {"sbu-orientation", "normal"},
|
||||
Package () {"hsl-orientation", "normal"},
|
||||
},
|
||||
})
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user