Arm Scmi Archicture

简介

Arm System Control and Management Interface

Discovery and self-description of the interfaces implemented by the platform.
Agent-specific resource isolation interfaces for dynamically configuring an SCMI-compliant agent’s access to devices and protocols.
Power domain management interfaces to place a given device or domain into the various power-saving states that it supports.

Performance management interfaces to control the performance of a domain which, in turn, is composed of compute engines, such as Application Processors (APs), GPUs, or other accelerators.
Clock management interfaces to set and enquire rates on platform-managed clocks.
Sensor management interfaces to read sensor data and be notified of sensor value changes.
Reset management interfaces to reset peripherals or reset domains.

Discovery and self-description of the interfaces it supports
Power domain management, which is the ability to place a given device or domain into the various power-saving states that it supports
Performance management, which is the ability to control the performance of a domain that is composed of compute engines such as application processors (APs), GPUs, or other accelerators.
Clock management, which is the ability to set and inquire rates on platform-managed clocks.
Sensor management, which is the ability to read sensor data, and be notified of sensor value changes.

fast channel support
Power Domain Management pre-notification suppor
Agent-specific Resource Isolation capability as a part of Base protocol.
Reset Management Protocol.
Renamed Mailbox Transport to more appropriate Shared Memory based Transport and made changes to allow SMC/HVC based doorbells.
Added support for notifications to agents on performance level change events triggered by external factors.

部份场景对性能有一定的要求（DVFS）

Hypervisor has access to all channels.
- Each channel has a unique agent-id allocated by System Controller.
  - Discoverable by BASE_DISCOVER_AGENT command
Hypervisor chooses channels to allocate to VMs.
Hypervisor configures access permissions of agents
- BASE_SET_DEVICE_PERMISSIONS
- BASE_SET_PROTOCOL_PERMISSIONS
- BASE_RESET_AGENT_CONFIGURATION
- Only one control channel has permissions to use above commands. Access control imposed at boot by System Controller.
- Control channel identification is done through firmware tables and is not discoverable.

Hypervisors maps configured channels into VM space and starts VM.
VM can use channel mapped to its space.
- Can send commands to access resources allowed by the hypervisor over the channel.