Abstract: Error correction code (ECC) checkbits are generated for each write access to a memory address based on both the data to be written (the write data) and the memory address. The ECC checkbits are stored with the data and, in response to a read access at the memory address, are employed to check for errors in both the address and the data provided in response to the read access (the read data). The ECC checkbit generation process can result, for particular memory addresses, in checkbits that can incorrectly indicate whether errors are present in the read data. Accordingly, the checkbits can be selectively inverted based on the memory address so that the checkbit pattern will not result in an incorrect error detection or correction.

Abstract: In a data processing system having a processor, a DMA controller, a peripheral, and a memory, a method includes initiating a DMA transfer between the peripheral and the memory, wherein the DMA transfer comprises N subsets of data to be transferred between the peripheral and the memory, N having a value of two or more; asserting, by the peripheral, an event status indicator each time an event is completed by the peripheral; in response to each assertion of the event status indicator, the peripheral, based on a data request enable signal from the DMA controller, performing one of asserting a data request signal provided to the DMA controller or providing an interrupt request to the processor; and in response to each assertion of the data request signal, the DMA controller initiating transfer of a next subset of data of the N subsets of data between the memory and the peripheral.

Abstract: An electronic system includes multiple data access components (DACs), a semaphores module, and a memory protection unit (MPU). Any of the DACs may issue an access request, which requests access to a shared system resource. A region descriptor associated with the shared system resource specifies default access permissions for the DACs. The semaphores module implements a semaphore for the shared system resource, and produces semaphore signals indicating which one, if any, of the DACs has locked the semaphore for the shared system resource. More particularly, an access evaluation circuit of the MPU receives the default access permissions and the semaphore signals. When the semaphore is properly enabled, as indicated in the region descriptor, the access evaluation circuit produces effective access permissions for the DACs by potentially altering the default access permissions based on the semaphore signals. The MPU grants or denies the access request based on the effective access permissions.

Abstract: A processor begins exception processing in response to an exception event. Exception processing by the processor is halted during exception processing to facilitate debugging. The exception event can be a reset exception event or an interrupt exception event. Normal exception processing by the data processor can be resumed after debugging, or exception processing by the data processor can be aborted to allow the normal execution of instructions by the data processor to resume. An exception event can be selectively treated as an interrupt or a reset.

Abstract: In response to determining an event has occurred, information is stored at a trace buffer of an integrated circuit. When the trace buffer is full, execution of instructions at a CPU is halted to allow the trace buffer information to be accessed at an external interface to the integrated circuit device. The CPU is continually halted as the trace buffer is filled to facilitate retrieving all information written to the trace buffer.

Abstract: Error correction code (ECC) checkbits are generated for each write access to a memory address based on both the data to be written (the write data) and the memory address. The ECC checkbits are stored with the data and, in response to a read access at the memory address, are employed to check for errors in both the address and the data provided in response to the read access (the read data). The ECC checkbit generation process can result, for particular memory addresses, in checkbits that can incorrectly indicate whether errors are present in the read data. Accordingly, the checkbits can be selectively inverted based on the memory address so that the checkbit pattern will not result in an incorrect error detection or correction.

Abstract: A system and method are disclosed for determining whether to allow or deny an access request based upon one or more descriptors at a local memory protection unit and based upon one or more descriptors a system memory protection unit. When multiple descriptors of a memory protection unit apply to a particular request, the least-restrictive descriptor will be selected. System access information is stored at a cache of a local core in response to a cache line being filled. The cached system access information is merged with local access information, wherein the most-restrictive access is selected.

Abstract: A system and method are disclosed for determining whether to allow or deny an access request based upon one or more descriptors at a local memory protection unit and based upon one or more descriptors a system memory protection unit. When multiple descriptors of a memory protection unit apply to a particular request, the least-restrictive descriptor will be selected. System access information is stored at a cache of a local core in response to a cache line being filled. The cached system access information is merged with local access information, wherein the most-restrictive access is selected.

Abstract: In a data processing system having a processor, a DMA controller, a peripheral, and a memory, a method includes initiating a DMA transfer between the peripheral and the memory, wherein the DMA transfer comprises N subsets of data to be transferred between the peripheral and the memory, N having a value of two or more; asserting, by the peripheral, an event status indicator each time an event is completed by the peripheral; in response to each assertion of the event status indicator, the peripheral, based on a data request enable signal from the DMA controller, performing one of asserting a data request signal provided to the DMA controller or providing an interrupt request to the processor; and in response to each assertion of the data request signal, the DMA controller initiating transfer of a next subset of data of the N subsets of data between the memory and the peripheral.

Abstract: A processor begins exception processing in response to an exception event. Exception processing by the processor is halted during exception processing to facilitate debugging. The exception event can be a reset exception event or an interrupt exception event. Normal exception processing by the data processor can be resumed after debugging, or exception processing by the data processor can be aborted to allow the normal execution of instructions by the data processor to resume. An exception event can be selectively treated as an interrupt or a reset.

Abstract: A processor begins exception processing in response to an exception event. Exception processing by the processor is halted during exception processing to facilitate debugging. The exception event can be a reset exception event or an interrupt exception event. Normal exception processing by the data processor can be resumed after debugging, or exception processing by the data processor can be aborted to allow the normal execution of instructions by the data processor to resume. An exception event can be selectively treated as an interrupt or a reset.

Abstract: In response to determining an event has occurred, information is stored at a trace buffer of an integrated circuit. When the trace buffer is full, execution of instructions at a CPU is halted to allow the trace buffer information to be accessed at an external interface to the integrated circuit device. The CPU is continually halted as the trace buffer is filled to facilitate retrieving all information written to the trace buffer.

Abstract: An embodiment of an electronic system includes a processing element, a bus controller, and a peripheral module. The processing element executes machine readable code for performing a data transfer of an x-bit wide data value between the processing element and the peripheral module. Performing the data transfer includes providing a processing element-provided address corresponding to a y-bit wide data register of the peripheral module, where y is less than x. The bus controller receives the processing element-provided address, and in response, performs a series of multiple data transfers with the peripheral module. This includes providing a first peripheral address for a first data transfer of the series, and providing at least one different peripheral address for at least one other data transfer of the series. The peripheral module maps the first peripheral address and the at least one different peripheral address to the y-bit wide data register.

Abstract: A flexible peripheral access protection mechanism within a data processing system (10, 100). In one embodiment, each master (14, 15) within the data processing system (10) includes a corresponding privilege level modifier (70, 74) and corresponding trust attributes (71, 72, 75, 76) for particular bus access types (e.g. read and write accesses). Also, in one embodiment, each peripheral (22, 24) within the data processing system (10) includes a corresponding trust attribute (80, 84), write protect indicator (81, 85), and a privilege protect indicator (82, 86). Therefore, in one embodiment, a bus access by a bus master to a peripheral is allowed when the bus master has the appropriate privilege level and appropriate level of trust required by the peripheral (and the peripheral is not write protected, if the bus access is a write access). Also, through the use of the privilege level modifiers, a the bus master can be forced to a particular privilege level for a particular bus access.

Abstract: A system and method for performance monitoring in processors is provided. The system and method evaluates the performance of the processor by counting selected events during one or more defined periods. The performance monitor provides improved performance characterization by providing highly-configurable start-stop control over the event counting.

Abstract: A method and device for processing direct memory access transfer requests is disclosed. The method includes executing a first transfer request associated with a channel of a DMA device, and determining if the next transfer request is associated with the same channel. If the next transfer request is associated with a different channel, the DMA device executes an arbitration process to determine the priority of the second transfer request relative to other pending transfer requests. If the next transfer request is associated with the same channel as the first transfer request, the DMA device executes the next transfer request without executing the normal arbitration process. By foregoing execution of the arbitration process when two transfer requests are associated with the same channel, the DMA device is able to begin execution of the transfer requests more quickly.

Abstract: A flexible peripheral access protection mechanism within a data processing system (10, 100), as disclosed herein, allows for a more secure operating environment. In one embodiment, each master (14, 15) within the data processing system (10) includes a corresponding privilege level modifier (70, 74) and corresponding trust attributes (71, 72, 75, 76) for particular bus access types (e.g. read and write accesses). Also, in one embodiment, each peripheral (22, 24) within the data processing system (10) includes a corresponding trust attribute (80, 84), write protect indicator (81, 85), and a privilege protect indicator (82, 86). Therefore, in one embodiment, a bus access by a bus master to a peripheral is allowed when the bus master has the appropriate privilege level and appropriate level of trust required by the peripheral (and the peripheral is not write protected, if the bus access is a write access).

Abstract: A system (10) implements user programmable addressing modes in response to control information contained within an input address. Encoded control information stored in a plurality of user programmed address permutation control registers (70-72) is used to determine what bit values are used to replace predetermined bits of the input address to selectively create a corresponding permutated address. Since no modification to a processor's pipeline is required, various permutation addressing modes may be user-defined and implemented using either a general-purpose processor or a specialized processor.

Abstract: A system (10) implements user programmable addressing modes in response to control information contained within an input address. Encoded control information stored in a plurality of user programmed address permutation control registers (70-72) is used to determine what bit values are used to replace predetermined bits of the input address to selectively create a corresponding permutated address. Since no modification to a processor's pipeline is required, various permutation addressing modes may be user-defined and implemented using either a general-purpose processor or a specialized processor.

Abstract: A most recently used bit (25) is used to determine if a data transfer should occur from a fill buffer (20) into a data memory (32) in a cache (15). If the data to be displaced in the data memory (32) has been referenced more recently than the data present in the fill buffer (20), then the transfer should not occur. When a cache miss does occur, a control register (50) is used to determine the conditions for loading the fill buffer (20).