Functional Description

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Revision History
Introduction
PCH Controller Device IDs
- Revision IDs
- Device IDs
Memory Mapping
- Functional Description
- Memory Map
Audio Voice and Speech
Ballout Definition
Connectivity Integrated (CNVi)
Controller Link
Direct Enhanced Serial Peripheral Interface (Direct eSPI)
Direct Media Interface (DMI)
Enhanced Serial Peripheral Interface (eSPI)
Gigabit Ethernet Controller
Host System Management Bus (SMBus) Controller
Integrated Sensor Hub (ISH)
Intel® Serial I/O Improved Inter-Integrated Circuit (I3C) Controllers
Intel® Serial I/O Inter-Integrated Circuit (I2C) Controllers
Intel® Serial I/O Universal Asynchronous Receiver/Transmitter (UART) Controllers
Intel® Serial IO Generic SPI (GSPI) Controllers
PCI Express* (PCIe*)
Real Time Clock (RTC)
- Signal Description
- I/O Signal Planes and States
Serial ATA (SATA)
Serial Peripheral Interface (SPI)
System Clocks
- Integrated Clock Controller (ICC)
  - Signal Descriptions
- I/O Signal Pin States
System Management Interface and SMLink
Touch Host Controller (THC)
Universal Serial Bus (USB)
General Purpose Input and Output
- Functional Description
- Signal Description
GPIO Serial Expander
Private Configuration Space Port ID
Security Firmware Engines
- Intel® Converged Security and Management Engine (Intel® CSME)
- Intel® Silicon Security Engine
System Management
- Theory of Operation
  - TCO Modes
Testability and Monitoring
- Signal Description
- I/O Signal Planes and States
Miscellaneous Signals
Processor Sideband Signals
- Signal Description
- I/O Signal Planes and States
Power Delivery
- Power and Ground Signals
Power Management
Thermal Sensor
Electrical Characteristics

GPIO Serial Expander (GSX) uses serial-to-parallel or parallel-to-serial shift register discrete components to increase number of the GPIO pins for system use. It expands in the multiples of 8 for input or output with 8 pins per expander. The total shift register component supported is 8, which can expand the GPIOs by up to 64.

The below figure illustrates a GPIO expansion topology with 16 GPIs and 16 GPOs.

GSX Topology - Example

Coming out of system reset, GSX is in reset with the following behaviors:

GSXSRESET# asserted by default. The signal remains asserted until BIOS/SW initialization has been completed and CxCMD.ST set to 1.
GSXSLOAD is 0 by default until CxCMD.ST is set to 1.
GSXSCLK is not toggling until CxCMD.ST is set to 1.

Private Configuration Space Port ID

Integrated Pull-ups and Pull-downs Private Configuration Space Port ID