The application needs to call XPm_RequestNode(). to request usage of peripheral/device. For example:
XStatus XPm_RequestNode (const u32 DeviceId, const u32 Capabilities, const u32 QoS, const u32 Ack);The arguments are as follows:
- Device ID
- Device ID of the PM device to be requested.
- Capabilities
- Device-specific capabilities are required, and can be combined.
The capabilities include:
- PM_CAP_ACCESS: Full access / functionality
- PM_CAP_CONTEXT: Preserve context
- PM_CAP_WAKEUP: Emit wake interrupts
- PM_CAP_UNUSABLE: Runtime suspend (Device is requested for a subsystem but the device is clock disabled)
- PM_CAP_SECURE: Secure access type (non-secure/secure)
- PM_CAP_COHERENT: Device coherency
- PM_CAP_VIRTUALIZED: Device virtualization
For more information, see OS and Libraries Document Collection (UG643).
- QoS
- Quality of Service (0-100) is required. Note: Currently QoS is only used for AI Engine clock frequency scaling and represents the divider value for the AI Engine clock. See AI Engine Clock Frequency Scaling.
- Ack
- Requested acknowledge type. Note: This argument is used only for Zynq UltraScale+ MPSoCs. For Versal devices, this argument value is always set to blocking.
If a device is already requested by a subsystem, you can call XPm_SetRequirement() to change its requirement. For
example:
XStatus XPm_SetRequirement (const u32 DeviceId, const u32 Capabilities, const u32 QoS, const u32 Ack);The application must release the device when it is no longer required. To
release the device, call XPm_ReleaseNode(). For
example:
XStatus XPm_ReleaseNode (const u32 DeviceId);