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1.. SPDX-License-Identifier: GPL-2.02 3=====================4Intel North Mux-Agent5=====================6 7Introduction8============9 10North Mux-Agent is a function of the Intel PMC firmware that is supported on11most Intel based platforms that have the PMC microcontroller. It's used for12configuring the various USB Multiplexer/DeMultiplexers on the system. The13platforms that allow the mux-agent to be configured from the operating system14have an ACPI device object (node) with HID "INTC105C" that represents it.15 16The North Mux-Agent (aka. Intel PMC Mux Control, or just mux-agent) driver17communicates with the PMC microcontroller by using the PMC IPC method18(drivers/platform/x86/intel_scu_ipc.c). The driver registers with the USB Type-C19Mux Class which allows the USB Type-C Controller and Interface drivers to20configure the cable plug orientation and mode (with Alternate Modes). The driver21also registers with the USB Role Class in order to support both USB Host and22Device modes. The driver is located here: drivers/usb/typec/mux/intel_pmc_mux.c.23 24Port nodes25==========26 27General28-------29 30For every USB Type-C connector under the mux-agent control on the system, there31is a separate child node under the PMC mux-agent device node. Those nodes do not32represent the actual connectors, but instead the "channels" in the mux-agent33that are associated with the connectors::34 35 Scope (_SB.PCI0.PMC.MUX)36 {37 Device (CH0)38 {39 Name (_ADR, 0)40 }41 42 Device (CH1)43 {44 Name (_ADR, 1)45 }46 }47 48_PLD (Physical Location of Device)49----------------------------------50 51The optional _PLD object can be used with the port (the channel) nodes. If _PLD52is supplied, it should match the connector node _PLD::53 54 Scope (_SB.PCI0.PMC.MUX)55 {56 Device (CH0)57 {58 Name (_ADR, 0)59 Method (_PLD, 0, NotSerialized)60 {61 /* Consider this as pseudocode. */62 Return (\_SB.USBC.CON0._PLD())63 }64 }65 }66 67Mux-agent specific _DSD Device Properties68-----------------------------------------69 70Port Numbers71~~~~~~~~~~~~72 73In order to configure the muxes behind a USB Type-C connector, the PMC firmware74needs to know the USB2 port and the USB3 port that is associated with the75connector. The driver extracts the correct port numbers by reading specific _DSD76device properties named "usb2-port-number" and "usb3-port-number". These77properties have integer value that means the port index. The port index number78is 1's based, and value 0 is illegal. The driver uses the numbers extracted from79these device properties as-is when sending the mux-agent specific messages to80the PMC::81 82 Name (_DSD, Package () {83 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),84 Package() {85 Package () {"usb2-port-number", 6},86 Package () {"usb3-port-number", 3},87 },88 })89 90Orientation91~~~~~~~~~~~92 93Depending on the platform, the data and SBU lines coming from the connector may94be "fixed" from the mux-agent's point of view, which means the mux-agent driver95should not configure them according to the cable plug orientation. This can96happen for example if a retimer on the platform handles the cable plug97orientation. The driver uses a specific device properties "sbu-orientation"98(SBU) and "hsl-orientation" (data) to know if those lines are "fixed", and to99which orientation. The value that these properties have is a string value, and100it can be one that is defined for the USB Type-C connector orientation: "normal"101or "reversed"::102 103 Name (_DSD, Package () {104 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),105 Package() {106 Package () {"sbu-orientation", "normal"},107 Package () {"hsl-orientation", "normal"},108 },109 })110 111Example ASL112===========113 114The following ASL is an example that shows the mux-agent node, and two115connectors under its control::116 117 Scope (_SB.PCI0.PMC)118 {119 Device (MUX)120 {121 Name (_HID, "INTC105C")122 123 Device (CH0)124 {125 Name (_ADR, 0)126 127 Name (_DSD, Package () {128 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),129 Package() {130 Package () {"usb2-port-number", 6},131 Package () {"usb3-port-number", 3},132 Package () {"sbu-orientation", "normal"},133 Package () {"hsl-orientation", "normal"},134 },135 })136 }137 138 Device (CH1)139 {140 Name (_ADR, 1)141 142 Name (_DSD, Package () {143 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),144 Package() {145 Package () {"usb2-port-number", 5},146 Package () {"usb3-port-number", 2},147 Package () {"sbu-orientation", "normal"},148 Package () {"hsl-orientation", "normal"},149 },150 })151 }152 }153 }154