The #UCIe specification primarily focus on the technical specifications of UCIe, including link initialization, #training, physical layer details, and management architecture. However, they do not explicitly detail a specific device enumeration process like that found in protocols like #PCIe. Let's analyze the available information and infer potential aspects of device enumeration in the context of UCIe.
- Software View of UCIe: The sources describe a high-level software view of UCIe, emphasizing compatibility with existing software investments for PCIe and #CXL. This suggests that UCIe leverages the #software paradigms of these #protocols, potentially including their enumeration models.
- UCIe Link DVSEC: UCIe devices utilize a Designated Vendor-Specific Extended Capability (DVSEC) to expose UCIe-specific capabilities. This mechanism, commonly used in PCIe, indicates that device discovery and capability identification could follow similar principles.
- Register-Based Configuration: UCIe relies heavily on register-based configuration for link management, parameter negotiation, and other functions. This implies that device enumeration might involve accessing and configuring specific registers to identify the device, its capabilities, and its resources.
- Management Capability Structures: The UCIe specification discuss Management Capability Structures, which are accessed through the UCIe #Memory Access Protocol (UMAP). These structures could hold information relevant to device identification and enumeration, such as Vendor ID and Device ID.
Based on the available information, a plausible UCIe device enumeration process could involve the following steps:
- Link Initialization and Training: Establish a functional UCIe link between the host and the device using the procedures outlined in the sources. This includes sideband initialization, mainband training, and parameter exchange.
- UCIe DVSEC Discovery: The host software identifies the presence of the UCIe Link DVSEC in the device's configuration space, confirming it as a UCIe device.
- Capability and Resource Discovery: The host software reads the UCIe Link DVSEC and other relevant registers to determine the device's capabilities, supported protocols (PCIe, CXL, streaming), and available resources.
- Management Structure Access: Using the UCIe Memory Access Protocol, the host software accesses the Management Capability Structures to retrieve detailed information about the device, potentially including its Vendor ID, Device ID, and specific functionalities.
- Protocol-Specific Enumeration: Depending on the negotiated protocol (PCIe, CXL), further enumeration might follow the established procedures of that protocol. For instance, if PCIe is used, the host would enumerate the device as a standard PCIe endpoint, utilizing the discovered capabilities.
- Multi-Protocol Support: The enumeration process might need to account for UCIe's multi-protocol capability. This could involve protocol negotiation and branching to appropriate enumeration routines based on the selected protocol.
- Shared Links: The UCIe specification mention the concept of shared UCIe links. The enumeration process would need to handle the complexity of multiple devices potentially sharing a single link.
It's crucial to emphasize that the detailed steps of the enumeration process are not explicitly described in the specification. The above is an inference based on the available information and general knowledge of device enumeration in similar protocols. Independent verification and consultation with UCIe specification documents might be necessary to confirm the accuracy of the proposed process.
VeriFast is semiconductor services and solution provider. We have good experience on working with UCIe 1.0/1.1 based verification. Our team has worked on UCIe Verification IP development and UCIe PHY Design IP Verification. If you are looking for engineering resources with UCIe expertise, do contact us.
