Abstract: Techniques are disclosed relating to power management within an integrated circuits. In one embodiment an apparatus is disclosed that includes a circuit and a power management unit. The power management unit is configured to provide, based on a programmable setting, an indication of whether an attempted communication to the circuit is permitted to cause the circuit to exit from a power-managed state. In some embodiments, the apparatus includes a fabric configured to transmit the attempted communication to the circuit from a device. In such an embodiment, the circuit is configured to exit the power-managed state in response to receiving the attempted communication. The fabric is configured to determine whether to transmit the attempted communication based on the indication provided by the power management unit.

Abstract: Various techniques for generating an output clock based on a reference clock. This disclosure relates to generating an output clock signal based on a reference clock signal. In one embodiment, a method includes generating, using information received from a control circuit, an output clock signal using both a first number of edges or an input clock signal and a second, different number of edges of the input clock signal. In this embodiment, the control circuit runs at a frequency that is less than a frequency of the input clock signal. The received information may indicate, for a pulse of the output clock signal, whether the pulse should be generated using the first number of edges or the second number of edges. In some cases, the second number of edges may be the first number of edges plus one. The first and second number of edges may be programmable quantities.

Abstract: A clock divider may provide a lower speed clock to a logic block portion, but during reset, the clock divider may not operate properly, causing the logic block portion to be reset at a clock frequency greater than the frequency for which that logic was designed. However, an extended reset may be employed in which the clock divider is reset normally first before the logic block portion, allowing that logic to be reset according to the divided clock (e.g., rather than a higher speed clock). An asynchronous reset may also be employed in which one or more clock dividers first emerge from reset before being provided with a (synchronized) high speed clock signal, causing the clock dividers to be in phase with each other. This may enable communication between different areas of an IC that might not otherwise be in proper phase with each other.

Abstract: A clock divider may provide a lower speed clock to a logic block portion, but during reset, the clock divider may not operate properly, causing the logic block portion to be reset at a clock frequency greater than the frequency for which that logic was designed. However, an extended reset may be employed in which the clock divider is reset normally first before the logic block portion, allowing that logic to be reset according to the divided clock (e.g., rather than a higher speed clock). An asynchronous reset may also be employed in which one or more clock dividers first emerge from reset before being provided with a (synchronized) high speed clock signal, causing the clock dividers to be in phase with each other. This may enable communication between different areas of an IC that might not otherwise be in proper phase with each other.

Abstract: Due to software bugs, hardware bugs, power fluctuations, cosmic rays, and various other causes, computing systems may from time to time enter various types of error states. This disclosure relates generally to the field of watchdog timers configured to take corrective action when a computing system enters such an error state. In various embodiments, this disclosure provides systems, methods, apparatuses, and computer-readable media for multi-tier watchdog timers. Such multi-tier watchdog timers may be configured to take different levels of corrective action at different times and/or under different conditions.

Abstract: Systems and methods for arbitrating among traffic from a coherence point to a switch fabric. A multi-level arbiter is used to avoid starvation while providing fairness and high bandwidth on the connection path between the coherence point and the switch fabric. A first level of arbitration selects packets with enough available credits for forwarding from the switch fabric on a downstream channel. The second level of arbitration arbitrates among short packets at a first arbiter and arbitrates among long packets at a second arbiter. The selected short packet and the selected long packet are forwarded to a third level of arbitration. The third level of arbitration alternates between long and short packets and forwards the selected packet to the switch fabric.

Abstract: Techniques are disclosed relating to reducing power consumption in integrated circuits. In one embodiment, an apparatus includes a cache having a set of tag structures and a power management unit. The power management unit is configured to power down a duplicate set of tag structures in responsive to the cache being powered down. In one embodiment, the cache is configured to provide, to the power management unit, an indication of whether the cache includes valid data. In such an embodiment, the power management unit is configured to power down the cache in response to the cache indicating that the cache does not include valid data. In some embodiments, the duplicate set of tag structures is located within a coherence point configured to maintain coherency between the cache and a memory.

Abstract: A method and apparatus for interfacing dynamic hardware power managed blocks and software power managed blocks is disclosed. In one embodiment, and integrated circuit (IC) may include a number of power manageable functional units. The functional units maybe power managed through hardware, software, or both. Each of the functional units may be coupled to at least one other functional unit through a direct communications link. A link state machine may monitor each of the communications links between functional units, and may broadcast indications of link availability to the functional units coupled to the link. Responsive to a software request to shut down a given link, or a hardware initiated shutdown of one of the functional units coupled to the link, the link state machine may broadcast and indication that the link is unavailable.

Abstract: A method and apparatus for dynamic clock and power gating and decentralized wakeups is disclosed. In one embodiment, an integrated circuit (IC) includes power-manageable functional units and a power management unit. Each of the power manageable functional units is configured to convey a request to enter a low power state to the power management unit. The power management unit may respond by causing a requesting functional unit to enter the low power state. Should another functional unit initiate a request to communicate with a functional unit currently in the low power state, it may send a request to that functional unit. The receiving functional unit may respond to the request by exiting the low power state and resuming operation in the active state.

Abstract: In an embodiment, a system includes an interrupt controller, one or more CPUs coupled to the interrupt controller, a communication fabric, one or more peripheral devices configured to generate interrupts to be transmitted to the interrupt controller, and one or more interrupt message circuits coupled to the peripheral devices. The interrupt message circuits are configured to generate interrupt messages to convey the interrupts over the fabric to the interrupt controller. Some of the interrupts are level-sensitive interrupts, and the interrupt message circuits are configured to transmit level-sensitive interrupt messages to the interrupt controller. At least one of the interrupts is edge-triggered. The system is configured to convert the edge-triggered interrupt to a level-sensitive interrupt so that interrupts may be handled in the same fashion.

Abstract: In an embodiment, a system includes at least one peripheral device, an interrupt controller, a memory controller, at least one CPU, and an interrupt message circuit coupled to the peripheral device. The interrupt message circuit may be coupled to receive the interrupt signal from the peripheral device, and may be configured to generate an interrupt message for transmission on a communication fabric. In some embodiments, there may be multiple peripherals which have independent paths through the fabric for memory operations to the memory controller. Each such peripheral may be coupled to an instance of the interrupt message circuit. In an embodiment, the interrupt is level sensitive. The interrupt message circuit may be configured to transmit interrupt set messages an interrupt clear messages to the interrupt controller, to indicate the levels.

Abstract: A system and method for maintaining accurate interrupt timestamps. A semiconductor chip includes an interrupt controller (IC) with an interface to multiple sources of interrupts. In response to receiving an interrupt, the IC copies and records the value stored in a main time base counter used for maintaining a global elapsed time. The IC sends an indication of the interrupt to a corresponding processor. Either an interrupt service routine (ISR) or a device driver requests a timestamp associated with the interrupt. Rather than send a request to the operating system to obtain a current value stored in the main time base counter, the processor requests the recorded timestamp from the IC. The IC identifies the stored timestamp associated with the interrupt and returns it to the processor.

Abstract: An SOC implements a security enclave processor (SEP). The SEP may include a processor and one or more security peripherals. The SEP may be isolated from the rest of the SOC (e.g. one or more central processing units (CPUs) in the SOC, or application processors (APs) in the SOC). Access to the SEP may be strictly controlled by hardware. For example, a mechanism in which the CPUs/APs can only access a mailbox location in the SEP is described. The CPU/AP may write a message to the mailbox, which the SEP may read and respond to. The SEP may include one or more of the following in some embodiments: secure key management using wrapping keys, SEP control of boot and/or power management, and separate trust zones in memory.

Abstract: A size and retry programmable multi-synchronous FIFO. In one embodiment, a multi-synchronous FIFO memory generally comprises a selectable number of addressable memory locations for storing information; read control means synchronized by a read clock for controlling pop transactions configured to read from one or more of the selected number of addressable memory locations; write control means synchronized by a write clock asynchronous to the read clock for controlling push transactions to write to one or more of the selected number of addressable memory locations; and selectable transaction retry control means configured to cause read control means to repeat selected pop transactions and/or cause write control means to repeat selected push transactions.

Abstract: An efficient delay locked loop (DLL) training protocol during a frequency change includes an integrated circuit with a memory physical layer (PHY) unit that includes a master DLL and a slave DLL. The master DLL may delay a first reference clock by an amount, and provide a reference delay value corresponding to the delay amount. The slave DLL may delay a second reference clock by a second amount based upon a received configuration delay value. An interface unit may generate the configuration delay value based upon the reference delay value. A power management unit may provide an indication that the frequency of the second reference clock is changing. In response to receiving the indication, the interface unit may generate a new configuration delay value that corresponds to the new frequency using a predetermined scaling value and provide the new configuration delay value to the memory PHY unit.

Abstract: A direct memory access (DMA) engine schedules data transfer requests of a data processing system according to both an assigned transfer priority and the deadline for completing a transfer.

Abstract: In one embodiment, an SOC includes multiple components including a CPU complex and one or more non-CPU components such as peripheral interface controllers, memory controllers, media components, etc. The SOC also includes an SOC debug control unit, which is coupled to receive detected debug events from the components. Each component may include a local debug control unit that is configured to monitor for various debug events within that component. The debug events may be specific to the component. The local debug control units may transmit detected events to the SOC debug control unit. The SOC debug control unit may detect one or more events from one or more components, and may halt the components of the SOC responsive to detecting the selected events.

Abstract: In an embodiment, an integrated circuit such may require that a full reset of the integrated circuit occur before the integrated circuit enters either a test mode or a functional mode. The integrated circuit may include a reset detector to detect that the reset has occurred, and the integrated circuit may not progress to the test mode or the functional mode unless the reset detector detects that the reset has occurred. Accordingly, if test mode is being entered, any user data that may have been stored in the integrated circuit during a preceding functional mode may have been cleared via the reset. Similarly, if normal mode is being entered, any test data that may have been stored in the integrated circuit in a preceding test mode may have been cleared via the reset.

Abstract: Systems and methods for coordinating performance parameters in multiple domains are described. In an embodiment, a method includes receiving a request to change a state of an electronic circuit, where the circuit includes a first domain and a second domain, causing a first parameter of a first circuit serving the first domain to be modified to a first modified parameter based on the request, and causing a second parameter of a second circuit serving the second domain to be modified to a second modified parameter based on the request. In some cases, a parameter may include a clock frequency. In other cases, a parameter may include a voltage. In some embodiments, a system may be implemented as a logic circuit and/or as a system-on-a-chip (SoC). Devices suitable for using these systems include, for example, desktop and laptop computers, tablets, network appliances, mobile phones, personal digital assistants, e-book readers, televisions, and game consoles.

Abstract: Adjusting a clock source of a device clock to reduce wireless communication (e.g., radio frequency (RF)) interference within a device. The device clock may be derived from an input clock to a serial interface, e.g., coupled to a display, and may be initially driven by a first clock. Later, it may be determined that the serial interface clock is or will interfere with wireless communication. Accordingly, temporary clock signals may be provided to the device clock while the first clock is modified. Once modified, the modified clock signals may be provided to the device clock to reduce wireless communication interference.