Arm Limited

Sean James Salisbury

Andrew David Tune

Arthur Brian Laughton

Daniel Adam Sara

Peter Andrew Riocreux

Eduard Vardanyan

Chiranjeev Acharya

Jamshed Jalal

Edward Martin McCombs, Jr

Mark David Werkheiser

Rahul Mathur

Alistair Crone Bruce

George Robert Scott Lloyd

Bruce James Mathewson

Tushar P Ringe

Akshay Kumar

Zheng Xu

Antony John Harris

Hsin-Yu Chen

Premkishore Shivakumar

Julian Jose Hilgemberg Pontes

Phani Raja Bhushan Chalasani

Charles Filip Brej

Andrew Brian Thomas Hopkins

Gaurav Kumar

A method for write operations to memory include starting write operations for writing n words in a same row, including loading a first word of the n words during a first clock cycle, where n is an integer greater than 1; loading one or more additional words of the n words, each during a corresponding one or more additional clock cycles; triggering the n words to be stored in the memory; and closing the write operations for the writing of the n words during a final clock cycle, whereby the n words are written in n+1 clock cycles consisting of the first clock cycle, the corresponding one or more additional clock cycles, and the final clock cycle. The write circuitry performing the aforementioned operations can also perform write operations for a single word in two clock cycles.

Increased throughput for writes to memory

Circuitry including cache storage and control circuitry is provided. The cache storage includes an array of random access memory storage elements, and is configured to store data in multiple cache sectors, each cache sector including a number of cache storage data units. The control circuitry is configured to control access to the cache storage including, for example, accessing the cache storage data units in the cache sectors. After accessing a cache storage data unit in a cache sector, the energy requirement and/or latency for the next access to a cache storage data unit in the same sector is lower than the energy requirement and/or latency for the next access to a cache storage data unit in a different same sector.

Circuitry and method

A burst read with flexible burst length for on-chip memory, such as, for example, system cache memory, hierarchical cache memory, system memory, etc. is provided. Advantageously, successive burst reads are performed with less signal toggling and fewer bitline swings.

Burst read with flexible burst length for on-chip memory

The present disclosure advantageously provides a system cache and a method for storing coherent data and non-coherent data in a system cache. A transaction is received from a source in a system, the transaction including at least a memory address, the source having a location in a coherent domain or a non-coherent domain of the system, the coherent domain including shareable data and the non-coherent domain including non-shareable data. Whether the memory address is stored in a cache line is determined, and, when the memory address is not determined to be stored in a cache line, a cache line is allocated to the transaction including setting a state bit of the allocated cache line based on the source location to indicate whether shareable or non-shareable data is stored in the allocated cache line, and the transaction is processed.

Cache for storing coherent and non-coherent data

There is provided an interconnect for transferring requests between ports in which the ports include both source ports destination ports. The interconnect includes storage circuitry for storing the requests. Input circuitry receives the requests from the plurality of source ports, selects at least one selected source port from an allowed set of said plurality of source ports, and transfers a presented request from the at least one selected source port to the storage circuitry. Output circuitry causes a request in said storage circuitry to be output at one of said plurality of destination ports. Counter circuitry maintains counter values for a plurality of tracked ports from amongst said ports, each counter value indicating the number of requests in said storage circuitry associated with a corresponding tracked port that are waiting to be output by said output circuitry and filter circuitry determines whether or not a given source port is in said allowed set in dependence on said counter circuitry.

Apparatus and method for buffered interconnect

Resizing circuitry comprises at least one buffer having buffer entries each corresponding to one of at least two shift registers, each shift register comprising storage circuits connected in a ring to transfer a token bit between storage circuits. Selection circuitry controls, based on the shift registers, writing of data sections of input data units having a first number of data sections to the buffer(s), to form output data units having a second number of data sections. For a given buffer entry corresponding to a given shift register, depending on whether the token bit is stored in a first or second subset of storage circuits, the selection circuitry controls writing of a selected data section of a received input data unit to the given buffer entry or prevents overwriting of the given buffer entry. At least two of the shift registers have different relative arrangements of the first and second subsets of storage circuits.

Resizing circuitry

An on-chip interconnect comprises control circuitry which responds to a burst read request received at an initiating requester interface, to control issuing of at least one read request to at least one target completer device via at least one target completer interface. For a chunking enabled burst read transaction, the control circuitry supports returning the requested data items to the initiating requester device in a number of data transfers, with an order of the data items in the data transfers permitted to differ from a default order and each data transfer specifying chunk identifying information identifying which portion of the data items is represented by returned data for that data transfer. For a data transfer returned to the initiating requester device based on data returned from one of a second subset of completer interfaces, the control circuitry generates the chunk identifying information to be specified by the given data transfer.

Chunking for burst read transactions

An interconnection network is provided for managing data transfer between a plurality of nodes of an integrated circuit. The interconnection network has at least one transmission path originating from an upstream location of the interconnection network, each transmission path being arranged to transmit data blocks from the upstream location to an associated downstream location within that transmission path. Digest generation circuitry is used to generate digests for data blocks, and fault detection circuitry provided in association with the upstream location is arranged to determine presence of a fault condition in the interconnection network. The digest generation circuitry is arranged to generate an upstream digest for a given data block at the upstream location, and to generate a corresponding downstream digest for the given data block at the associated downstream location. The fault detection circuitry is arranged to receive upstream digests from the upstream location and corresponding downstream digests received via a return path from each downstream location, and to determine presence of the fault condition based on a comparison of each upstream digest with its corresponding downstream digest.

Interconnection network for integrated circuit with fault detection circuitry provided locally to an upstream location

A method comprises generating, using a computer, an integrated circuit layout including a plurality of data handling nodes interconnected by routing circuitry defining data packet routes between the plurality of data handling nodes; for a transaction source node configured to generate data packets associated with a data handling translation between that transaction source node and a transaction target node and having one or more routing data fields controlling routing of the data packet, detecting, using the computer, a difference between a first routing controlled by the one or more routing data fields and a selected second routing provided by the integrated circuit layout; and providing, using the computer, one or more data mapping nodes in the integrated circuit layout to map an initial value of one or more of the routing data fields of a data packet generated by the transaction source node to a mapped data value, so that the mapped data value controls routing of the data packet using the selected second routing.

Integrated circuit design and fabrication

Data access routing circuitryis provided for routing data access request to a selected destination node. The data access routing circuitry supports read requests requiring a read response, write requests requiring a write response and at least one type of atomic data access request requiring both a read response and a write response. Resource allocation circuitryis provided to control allocation of resource for handling data access requests which require a read response. The resource allocation circuitryreserves resource for handling the at least one type of atomic data access request and prevents use of the reserved resourcefor handling read requests.

Resource allocation for atomic data access requests

An interconnect, and method of handling supplementary data in an interconnect, are provided. The interconnect has routing circuitry providing a plurality of paths, and routing control circuitry to use the plurality of paths to establish routes through the interconnect between source devices and destination devices coupled to the interconnect, to enable system data to be routed through the interconnect between the source devices and the destination devices. The system data relates to functional operation of a system comprising the interconnect, the source devices and the destination devices. At least a subset of the paths are redundant paths whose use by the routing control circuitry provides the system data with resilience to faults when routing the system data through the interconnect. The routing control circuitry is responsive to supplementary data which is unnecessary to ensure the functional operation of the system, to establish a supplementary data route through the interconnect to a supplementary data receiving circuit, such that the supplementary data route employs at least one of the redundant paths that is not required to provide resilience for the system data at a time the at least one of the redundant paths is used for the supplementary data route. This provides an efficient mechanism for transporting supplementary data, whilst ensuring non-intrusive behaviour.

Interconnect and method of handling supplementary data in an interconnect

An interconnect for providing data access between nodes of an integrated circuit, comprises a predetermined type of ingress port comprising routing circuitry responsive to a read-triggering request received from a requesting node to select from a selected egress port via which signals are to be routed to a destination node to control the destination node to return at least one read response dependent on data read from a target storage location. In response to the read-triggering request, the routing circuitry obtains a relative data width indication specifying whether read responses received at the selected egress port have a narrower data width than read responses to be provided to the requesting node by the predetermined type of ingress port, and controls allocation of resource for handling the read-triggering request or the at least one read response depending on the relative data width indication.

Relative data width indication for read responses routed by an interconnect

Transaction handling apparatus comprises a response buffer; and tracking circuitry to store data defining each transaction issued by one or more transaction master devices and to control routing of a transaction response to a given transaction either to the response buffer or as an output to the transaction master device which issued the given transaction; the response buffer being configured to access an indicator for each buffered transaction response indicating whether a response has been output by the apparatus for a previously issued transaction, on which that buffered transaction response depends, and to output the buffered transaction response to the transaction master device which issued that transaction when the previously issued transaction has already been output by the apparatus.

Transaction handling

A cache coherency controller comprises a directory indicating, for memory addresses cached by one or more of a group of one or more cache memories connectable in a coherent cache structure, which of the cache memories are caching those memory addresses; and control circuitry configured to detect a directory entry relating to a memory address to be accessed so as to coordinate, amongst the cache memories, an access to a memory address by one of the cache memories or a coherent agent in instances when the directory entry indicates that another of the cache memories is caching that memory address; the control circuitry being responsive to status data indicating whether each cache memory in the group is currently subject to cache coherency control so as to take into account, in the detection of the directory entry relating to the memory address to be accessed, only those cache memories in the group which are currently subject to cache coherency control.

Cache coherency

A cache coherency controller comprises a directory indicating, for memory addresses cached by a group of two or more cache memories in a coherent cache structure, which of the cache memories are caching those memory addresses, the directory being associative so that multiple memory addresses map to an associative set of more than one directory entry; and control logic responsive to a memory address to be newly cached, and configured to detect whether one or more of the set of directory entries mapped to that memory address is available for storage of an indication of which of the two or more cache memories are caching that memory address; the control logic being configured so that when all of the set of directory entries mapped to that memory address are occupied, the control logic is configured to select one of the set of directory entries as a directory entry to be overwritten and the corresponding cached information to be invalidated, the control logic being configured to select a directory entry to be overwritten, from the set of directory entries, in dependence upon which of the group of two or more cache memories is indicated by that directory entry, according to a likelihood of selection amongst the two or more cache memories.

Growing community of inventors

Appley Bridge, United Kingdom

Sean James Salisbury