6.10.14 PCIESS
Peripheral Component Interconnect Express (PCIE) controllers provide a high-speed glueless serial interconnect to peripherals utilizing high bandwidth applications.
PCIe module is a multi-lane I/O interconnect that provides low pin-count, high reliability, and high-speed data transfer at rates of up to 5.0 Gbps per lane, per direction, for serial links on backplanes and printed curcuit boards. It is a 2nd generation I/O interconnect technology succeeding PCI and ISA bus designed to be used as a general-purpose serial I/O interconnect. It is also used as a bridge to other interconnects such as SATA, USB2/3.0, GbE MAC, and so forth.
The PCI Express standard's predecessor - PCI, is a parallel bus architecture that is increasingly difficult to scale-up in bandwidth, which is usually performed by increasing the number of data signal lines. The PCIe architecture was developed to help minimize I/O bus bottlenecks within systems and to provide the necessary bandwidth for high-speed, chip-to-chip, and board-to-board communications within a system. It is designed to replace the PCI-based shared, parallel bus signaling technology that is approaching its practical performance limits while simplifying the interface design.
PCIe module supports the following features:
- Dual operation mode: Root Complex (RC) or End Point (EP)
- Supports a single bidirectional link interface (a single input port and a single output port) with one lane
- Operated at a raw speed of 2.5 Gbps or 5.0 Gbps per lane per direction
- Maximum outbound payload size of 128 bytes
- Maximum inbound payload size of 256 bytes
- Maximum remote read request size of 256 bytes
- Ultra-low transmit and receive latency
- Support for dynamic-width conversion
- Automatic lane reversal
- Polarity inversion on receive
- Single virtual channel (VC)
- Single traffic class (TC)
- Single function in End Point (EP) mode
- Automatic credit management
- ECRC generation and checking
- PCI device power management with the exception of D3cold with Vaux
- PCI Express active state power management (ASPM) state L0s and L1
- PCI Express link power management states, except L2 state
- PCI Express advanced error reporting
- PCI Express messages for both transmit and receive
- Filtering for posted, non-posted, and completion traffic
- Configurable BAR filtering, I/O filtering, configuration filtering, and completion lookup/timeout
- Access to configuration space registers and external application memory-mapped registers through BAR0 and through configuration access
- Legacy interrupts reception (in RC) and generation (in EP)
- MSI generation and reception
- PHY loopback in RC mode
PCIe module does not support the following features:
- No support for multiple lanes
- No support for multiple VCs
- No support for multiple TCs
- No support for function-level reset
- No support for PCI Express beacon for in-band wake
- No built-in hardware support for hot-plug
- No support for vendor messaging
- No support for I/O access in inbound direction in RC or EP mode
- No support for addressing modes other than incremental for burst transactions. Thus, the PCIe addresses cannot be in cacheable memory space
- No auxiliary power to maintain controller context when rezuming from D3cold state
- No support for L2 link state
For more information, see section Peripheral Component Interconnect Express Subsystem (PCIe SS) in chapter Peripherals of the Device TRM.