Abstract: In a data processing apparatus 1 having registers 6, when a state saving trigger event occurs while a result value of a data processing operation is still to be written to a destination register then saving and restoring control circuitry 12 selects a state saving sequence defining a temporal order for saving register values to a backup data store 10. The sequence is selected to provide the destination register with a position within the sequence corresponding to a time after the result value has been written to the destination register. The register values are then saved to the backup data store 10 in the order of the selected state saving sequence. A similar technique can be used when a state restoring trigger event triggers loading of the data values from the backup data store 10 to the registers 6.

Abstract: A data processing system is provided with a programmable memory protection unit 10 defining a plurality of programmable memory regions 2, 4, 6, 8 each with associated programmable memory attributes. A default memory protection unit 22 is provided and defines a plurality of default memory regions a, b, c, d, e each with associated default memory attributes. If a miss occurs in the programmable memory protection unit 10, and the memory access is a privileged level memory access, then the default memory protection unit 22 will return default memory attributes for that memory request.

Abstract: A data processing apparatus includes a processor for processing data and having memory interface logic for controlling transfer of data to a memory. Also included is a memory for storing data processed by said processor. The processor is powered in a first domain and the memory is powered in a second domain. A system bus is coupled to the processor and the memory to transfer data therebetween in response to memory transfer requests. The processor is responsive to a low power request to enter a low power mode to control transfer of state data indicating a current state of the processor to the memory via the system bus using memory interface logic. The state data is sufficient to restore the processor to an equivalent program state following exit from the low power mode, store the state data in memory; and power down the first domain.

Abstract: In a data processing apparatus 1 having registers 6, when a state saving trigger event occurs while a result value of a data processing operation is still to be written to a destination register then saving and restoring control circuitry 12 selects a state saving sequence defining a temporal order for saving register values to a backup data store 10. The sequence is selected to provide the destination register with a position within the sequence corresponding to a time after the result value has been written to the destination register. The register values are then saved to the backup data store 10 in the order of the selected state saving sequence. A similar technique can be used when a state restoring trigger event triggers loading of the data values from the backup data store 10 to the registers 6.

Abstract: An interrupt controller and method are provided for handling interrupt requests generated by a plurality of interrupt sources. The interrupt controller comprises pend logic for receiving interrupt requests generated by the plurality of interrupt sources, and for each interrupt request, determining whether to accept that interrupt request for handling by the interrupt controller. Interrupt handling logic then selects an interrupt request from amongst those interrupt requests accepted by the pend logic, and generates an indication of the interrupt routine to be executed by a processor to process that interrupt request. The pend logic is arranged, for each of the interrupt sources, to detect a transition of the associated interrupt request from an unset state to a set state, and to accept the interrupt request upon such detection.

Abstract: An interrupt controller for managing interrupt requests comprises interrupt control circuitry in a first domain, the first domain being switchable to a low-power mode, and interrupt request monitoring circuitry in a second domain. The interrupt control circuitry is responsive to a low power request signal received by the interrupt controller to communicate interrupt select information to the interrupt request monitoring circuitry prior to the first domain being switched to a low power mode, the interrupt select information identifying interrupt requests which indicate exit from the low power mode. The interrupt request monitoring circuitry comprises a select information store configured to store the select information communicated to the interrupt request monitoring circuitry by the interrupt control circuitry.

Abstract: A data processing apparatus comprising: a processor for processing data, said processor comprising memory interface logic for controlling transfer of data to a memory, said processor being powered in a first power domain; a memory for storing data processed by said processor said memory being powered in a second power domain; a system bus coupled to said processor and said memory and operable to transfer data between said processor and said memory in response to memory transfer requests issued upon said system bus by said memory interface logic during normal processing operation of said processor and said memory; wherein said processor is responsive to a low power request indicating said data processing apparatus should enter a low power mode to: control transfer of state data indicating a current state of said processor to said memory via said system bus using said memory interface logic, said state data being sufficient data to restore said processor to an equivalent program state following exit from said l

Abstract: An interrupt controller for managing interrupt requests comprises interrupt control circuitry in a first domain, the first domain being switchable to a low-power mode, and interrupt request monitoring circuitry in a second domain. The interrupt control circuitry comprises interrupt inputs for receiving interrupt requests and is configured to selectively output a received interrupt request to data processing logic. The interrupt control circuitry is responsive to a low power request signal received by the interrupt controller to communicate interrupt select information to the interrupt request monitoring circuitry prior to the first domain being switched to a low power mode, the interrupt select information identifying interrupt requests which indicate exit from the low power mode. The interrupt request monitoring circuitry comprises a select information store configured to store the select information communicated to the interrupt request monitoring circuitry by the interrupt control circuitry.

Abstract: A data processing system is provided with a programmable memory protection unit 10 defining a plurality of programmable memory regions 2, 4, 6, 8 each with associated programmable memory attributes. A default memory protection unit 22 is provided and defines a plurality of default memory regions a, b, c, d, e each with associated default memory attributes. If a miss occurs in the programmable memory protection unit 10, and the memory access is a privileged level memory access, then the default memory protection unit 22 will return default memory attributes for that memory request.

Abstract: An interrupt controller and method are provided for handling interrupt requests generated by a plurality of interrupt sources. Th interrupt controller comprises pend logic for receiving interrupt requests generated by the plurality of interrupt sources, and for each interrupt request determining whether to accept that interrupt request for handling by the interrupt controller. Interrupt handling logic then selects an interrupt request from amongst those interrupt requests accepted by the pend logic, and generates an indication of the interrupt routine to be executed by a processor to process that interrupt request. The pend logic is arranged, for each of the interrupt sources, to detect a transition of the associated interrupt request from an unset state to a set state, and to accept the interrupt request upon such detection.