1.. SPDX-License-Identifier: GPL-2.0 2 3===================== 4Intel North Mux-Agent 5===================== 6 7Introduction 8============ 9 10North Mux-Agent is a function of the Intel PMC firmware that is supported on 11most Intel based platforms that have the PMC microcontroller. It's used for 12configuring the various USB Multiplexer/DeMultiplexers on the system. The 13platforms that allow the mux-agent to be configured from the operating system 14have 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) driver 17communicates with the PMC microcontroller by using the PMC IPC method 18(drivers/platform/x86/intel_scu_ipc.c). The driver registers with the USB Type-C 19Mux Class which allows the USB Type-C Controller and Interface drivers to 20configure the cable plug orientation and mode (with Alternate Modes). The driver 21also registers with the USB Role Class in order to support both USB Host and 22Device modes. The driver is located here: drivers/usb/typec/mux/intel_pmc_mux.c. 23 24Port nodes 25========== 26 27General 28------- 29 30For every USB Type-C connector under the mux-agent control on the system, there 31is a separate child node under the PMC mux-agent device node. Those nodes do not 32represent the actual connectors, but instead the "channels" in the mux-agent 33that 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 _PLD 52is 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 Properties 68----------------------------------------- 69 70Port Numbers 71~~~~~~~~~~~~ 72 73In order to configure the muxes behind a USB Type-C connector, the PMC firmware 74needs to know the USB2 port and the USB3 port that is associated with the 75connector. The driver extracts the correct port numbers by reading specific _DSD 76device properties named "usb2-port-number" and "usb3-port-number". These 77properties have integer value that means the port index. The port index number 78is 1's based, and value 0 is illegal. The driver uses the numbers extracted from 79these device properties as-is when sending the mux-agent specific messages to 80the 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 90Orientation 91~~~~~~~~~~~ 92 93Depending on the platform, the data and SBU lines coming from the connector may 94be "fixed" from the mux-agent's point of view, which means the mux-agent driver 95should not configure them according to the cable plug orientation. This can 96happen for example if a retimer on the platform handles the cable plug 97orientation. The driver uses a specific device properties "sbu-orientation" 98(SBU) and "hsl-orientation" (data) to know if those lines are "fixed", and to 99which orientation. The value that these properties have is a string value, and 100it 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 ASL 112=========== 113 114The following ASL is an example that shows the mux-agent node, and two 115connectors 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