Abstract:
Systems-on-chip are designed with different IPs that use different data protection schemes. Modules are used between the IPs, and the modules convert between protection schemes. Protection schemes can be per-byte, word, packet, flit, or burst. Conversion can involve splitting, merging, encapsulation, conversion, and generation of redundant information. Encoding of redundancy according to protection schemes can occur directly at an IP interface or within an interconnect, such as within a packet-based NoC. Designs include SoCs, hardware description language code describing functions within SoCs, and non-transient computer readable media that store such source code.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention is in the field of system-on-chip and, more specifically, schemes for data error protection. 
       BACKGROUND 
       [0002]    Protection schemes involve encoding redundant information with data for transmission or storage, and later checking that the data and redundant information are consistent. Numerous protection schemes are well known, including triplication, parity, error correction codes (ECC), and 8b10b encoding. Protection schemes apply to any of source data, addresses, packet headers, and other useful transferred information, all of which are data in the context of adding redundant information. 
         [0003]    Different protection schemes have different amounts of redundant information, such as two bits per bit of data for triplication, one bit per byte of data for per-byte parity, one bit per multi-byte word of data for per-word parity, four bits per byte of data for per-byte ECC providing a protection level of single error correction (SEC), or five bits per byte of data for per-byte ECC providing a protection level of single error correction and double error detection (SECDED). A byte is eight bits.  FIG. 1  shows a table of the number of bits of redundant information needed to provide SEC ECC and SECDED ECC for ranges of numbers of data bits. 
         [0004]    Systems-on-chips (SoCs) are designed with hardware description language (HDL) code. Verilog, SystemVerilog, very high-speed integrated circuit hardware description language (VHDL), and SystemC are HDLs. 
         [0005]    Some applications of SoCs, such as automobile safety systems, industrial automation equipment, and data centers require that on-chip data, processing, storage, and communication functions are error resilient. That means that they if their physical structures wear out over time or they have manufacturing defects or they are impacted by alpha particle radiation that causes data to become corrupted, that corruption will be detected or detected and corrected. 
         [0006]    Modern SoCs include semiconductor intellectual property (IP) cores, integrated in communication with each other, to perform different useful functions. Some common IPs are central processing units (CPU)s, dynamic random access memory (DRAM) controllers, static random access memory (SRAM) buffers, graphics processing units (GPU)s, and direct memory access (DMA) engines. Most modern SoCs connect the IPs using an interconnect IP. Some common types of interconnects are crossbars, networks-on-chip (NoC)s, and meshes. SoC designers often procure such IPs from third-party IP vendors who provide HDL source code. 
         [0007]    IPs designed for SoCs for error resilient applications use parity or ECC or other types of protection schemes. However, different IPs use different protection schemes. For example a CPU master IP, such as the 32-bit ARM R5 CPU, can uses 32-bit SECDED ECC scheme and a 128-bit Flash memory controller can use a 128-bit SECDED ECC scheme. What is needed is a way for the two to be properly connected in an SoC. Furthermore, what is needed is a way to make an interconnect IP configurable as HDL code in order to provide for connecting IPs with inherently incompatible protection schemes. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention pertains to chips, systems, method, and HDL code that perform conversion between protection schemes. Embodiments of the invention enable IPs that use different protections schemes to communicate. An encoder unit accomplishes this by receiving redundant information according to one scheme and encoding either the same or different redundant information according to another scheme. This is useful in interconnects within SoCs. In some embodiments the interconnect uses a protection scheme that is the same as one of the IPs but in other embodiments the interconnect uses a unique protection scheme. 
         [0009]    The invention also encompasses the challenge of data changing within the interconnect, such as due to a change in serialization due to a decrease in data bus width, or a firewall that modifies a packet header. In either case, in each of some protection schemes, correctness must be checked and redundant information recalculated within the interconnect. 
         [0010]    The hardware design and the method of operation of SoCs can embody the invention. Furthermore, HDL code can embody the invention and one or more non-transient computer readable media that store such HDL code can embody the invention. HDL code that is a parity conversion placeholder embodies the invention, as it provides another designer the interfaces that enable communication between heterogeneous IPs that use different protection schemes. Some third-party interconnect configuration tools generate such HDL code in order to enable chip designers to implement application-specific protection scheme conversion. 
         [0011]    Some embodiments encapsulate the redundant information receive from a receiving interface within the information sent on the sending interface. Some embodiments convert the form of the same redundant information received on the receiving interface as the information sent on the sending interface. Some embodiments receive redundant information, perform a consistency check, encode different redundant information, and send that. 
         [0012]    Some embodiments assert a signal, such as in the form of a pulse, when a checker detects an error. Some embodiments check consistency and count errors detected. Some embodiments that use ECC count errors corrected, and separately count uncorrected errors. 
         [0013]    Encoders embody the invention if the convert from any one to any other protection scheme. This includes conversion from or to any of parity, ECC, a different form of parity, a different form of ECC, SEC ECC, and SECDED ECC. Furthermore, some embodiments apply a protection scheme per-byte, some per-word, some per flow control unit (flit), some per packet, and some per burst. 
         [0014]    Some embodiments apply protection schemes per multi-byte word, but split the redundant information and transport each portion with a different byte. This is helpful if word size and re-serialization changes are present in the interconnect. Some embodiments encode other sideband information that relates to the data transfer, but is no part of the protection scheme with the received or sent data. Some such sideband information is status, control commands, and credits. 
         [0015]    Some encoders according to the invention receive data of one word size and send data of another word size. Accommodating such data width conversion necessitates protection scheme conversion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  a table of the number of bits of redundant information needed for SEC ECC and for SECDED ECC for ranges of data bits. 
           [0017]      FIG. 2  illustrates a master and a slave IP core, each with different protection schemes. 
           [0018]      FIG. 3A  illustrates two IP cores coupled through an encoder. 
           [0019]      FIG. 3B  illustrates an encoder with a receiving interface and a sending interface. 
           [0020]      FIG. 4A  illustrates a non-transient computer-readable medium. 
           [0021]      FIG. 4B  illustrates source code for a placeholder for an encoder. 
           [0022]      FIG. 5A  illustrates a non-transient computer-readable medium. 
           [0023]      FIG. 5B  illustrates source code for a placeholder for a checker. 
           [0024]      FIG. 6  illustrates IPs and a NoC within an SoC, the NoC performing encoding, packetizing, transport, depacketizing, and checking. 
           [0025]      FIG. 7  illustrates a NoC that performs packetizing, encoding, transport, checking, further transport, checking, and depacketizing. 
           [0026]      FIG. 8  illustrates units of a NoC that perform packetizing, encoding, transport, checking, modification, encoding, further transport, checking, and depacketizing. 
           [0027]      FIG. 9  illustrates a checker/encoder that receives per-byte parity and sends per-word SECDED ECC. 
           [0028]      FIG. 10  illustrates a checker/encoder that receives per-word SEC ECC and sends per-word SECDED ECC. 
           [0029]      FIG. 11  illustrates a checker/encoder that receives per-word SECDED ECC and control information, and sends per-byte SECDED ECC, control word parity, and counts of detected and corrected errors. 
           [0030]      FIG. 12  illustrates an encoder that receives per-nibble parity and encapsulates it as per-byte information. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    The invention is described in accordance with the aspects and embodiments in the following description with reference to the FIGs., in which like numbers represent the same or similar elements. Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” “in certain embodiments,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. It is noted that, as used in this description, the singular forms “a,” “an” and “the” include plural referents, unless the context clearly dictates otherwise. 
         [0032]    The described features, structures, or characteristics of the invention may be combined in any suitable manner in accordance with the aspects and one or more embodiments of the invention. In the following description, numerous specific details are recited to provide an understanding of various embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the aspects of the invention. 
         [0033]    All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or system in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed. 
         [0034]    Many SoCs include IPs with interfaces for sending and receiving data. As shown in  FIG. 2 , each interface is either a master type or a slave type, each of which is designed to be coupled to the other. Interfaces include various signals, as prescribed by protocols, and data is normally one of the signals. Other signals, which are involved in controlling the exchange of data between masters and slaves, are omitted from interfaces depicted in the figures of this patent. 
         [0035]    Each data signal has an inherent number of bits, also known as the width or the size of the signal. Bits of signals are conventionally indexed starting at zero. Therefore, a 32-bit signal has bits  0  to  31 , which are notated, as in  FIG. 2 , [31:0]. Data protection is part of some interface protocols. Some protocols encode the redundant information within the data signal, but many protocols transfer redundant information as separate signals. In  FIG. 2 , IP A has a 32-bit data bus and a 4-bit parity protection scheme whereas IP B has a 32-bit data bus and a 7-bit ECC protection scheme. Naturally, the interface protocols of IP A and IP B are incompatible and so the master and slave interfaces cannot be directly connected. 
         [0036]      FIG. 3( a )  shows an embodiment of the invention in which IP A and IP B are coupled through an encoder  300 . IP A sends, and encoder  300  receives, data and 7-bit ECC through interface  302 . The encoder  300  calculates a 4-bit party signal. Furthermore, encoder  300  sends, and IP B receives, data and 4-bit party through interface  304 . 
         [0037]      FIG. 3( b )  shows encoder  300 , which includes a receiving interface and a sending interface. The receiving interface includes a 32-bit data signal and a 4-bit parity signal. The sending interface includes a 32-bit data signal and a 7-bit ECC signal. The sending interface sends the same data values as received on the receiving interface. Different embodiments of the invention have different internal design of the encoder  300  that may use different parity encoding functions, may perform an ECC checking function, will have varying amounts of delay, and have varying other attributes of protection scheme encoding. 
         [0038]      FIG. 4( a )  depicts a negative-and (NAND) flash memory chip  400 . This is a type of non-transient computer readable medium on which source code is stored according to some embodiments of the invention. Some other embodiments use other types of computer readable media such as hard disk drives, compact disk read-only memory (CD-ROM), and punch cards. 
         [0039]      FIG. 4( b )  depicts a source code file  410  that is in accordance with some aspects of the invention. It is a module, written in the SystemVerilog HDL language. It includes inputs of a receiving interface with a 32-bit data signal and a 4-bit parity signal and it includes outputs of a sending interface with a 32-bit data signal and a 7-bit ECC signal. The aspects of the invention as embodied in this is particular embodiment of the invention is a placeholder module. It enables a designer to add code that describes the function of an encoder. 
         [0040]    A vendor of third-party interconnect IP provides such a module to chip designers so that they are able to effectively customize the interconnect IP according to their desired error protection scheme. That way the interconnect IP provider need not learn the chip designers requirements to customize the interconnect IP and the chip designers need not redesign the interconnect IP for their requirements. 
         [0041]      FIG. 5( a )  depicts the non-transient computer readable NAND flash memory  500 , arranged to store the source code file  510 , as shown in  FIG. 5( b ) . The source code of file  510  is a SystemVerilog checker placeholder according to an aspect and embodiment of the invention. It includes a receiving interface with a 32-bit data input signal and a 7-bit ECC signal. The module further includes output signal, err_pulse, which produces a pulse when the checker detects an error. Such a pulse is useful to interrupt a CPU so that it can handle such an error condition. The module further includes output 10-bit signals err_cor and err_unc. Those signals are driven by counter registers, corrected_errors and uncorrected_errors. The placeholder code allows a chip designer to count the number of errors detected through the ECC protection scheme and count the number of errors that corrected over time. 
         [0042]      FIG. 6  shows IPs within a SoC according to various aspects in an embodiment of the invention. IP A is coupled to IP B through a NoC interconnect IP  600 . NoC  600  facilitates and performs error resilient packet-based communication. For that, NoC  600  includes various units that operate on information sent from IP A to IP B. In sequence, encoder unit  602  generates redundant information according to a protection scheme as shown in  FIG. 4 . Packetizing unit  604  encodes data and redundant information in packets that include headers, and for some packets, payloads. Network  606  transports packets between IPs, and in some embodiments serves to transport packets between many IPs other than IP A and IP B. Depacketizing unit  608  receives packets from network  606  and presents the data and redundant information to checking unit  610 . Checking unit  610  checks the data and redundant information for consistency, and indicates errors as shown in  FIG. 6 . 
         [0043]    Whereas NoC  600  performs encoding before packetizing and checking after depacketizing,  FIG. 7  shows a NoC  700  in which packetizing unit  702  packetizes data for transport. Encoding unit  704  calculates redundant information according to a protection scheme. Network  706  transports protected packets to checking unit  708 , which checks consistency and reports errors. Network  710  transports unmodified packets to checker  712 , which checks consistency and reports errors. In accordance with the aspects of the invention, different embodiments have various numbers of checkers through which packets pass within a NoC. According to the embodiment of  FIG. 7 , checked packets proceed through depacketizing unit  714 . 
         [0044]      FIG. 8  shows the units of a NoC according to aspects of invention as shown in another embodiment. Packetizing unit  802  packetizes data. Encoder unit  804  calculates redundant information and encodes protected packets. Network  806  transports packets to checker unit  808 , which check consistency and reports errors. Modification unit  810  modifies the packet format. In some embodiments, modification involves changing the payload data, such as by changing the serialization and in some embodiments modification involves changing the packet header, which for the purposes of protection schemes is data from which redundant information is calculated. Encoder unit  812  calculates redundant information for the modified packet, according to a protection scheme. In some embodiments, the protection scheme used by encoding unit  804  and the protection scheme used by encoder unit  812  are the same scheme, but in some embodiments, they are different schemes. Network  814  transports packets to checking unit  816 , which checks consistency and reports errors. Depacketizing unit  818  depacketizes the packets and presents the data to a connected IP. 
         [0045]    In some embodiments, depacketizing unit  818  is a widening serialization adapter. It concatenates a multiplicity of incoming data words into a wider outgoing data word. For such, encoder unit  812  concatenates the bits of the incoming parity of multiple data words into a parity signal for the wider outgoing data word. 
         [0046]    In some embodiments, depacketizing unit  818  is a narrowing serialization adapter. It splits incoming data words into a multiplicity of narrower outgoing data words. For such, encoder unit  812  checks a certain number of ECC bits for the wide incoming data words and encoder unit  812  encodes a smaller number of ECC bits for each narrower outgoing data word. 
         [0047]    In some embodiments, depacketizing unit  818  is a firewall unit. It checks software-defined security bits in packet headers, and in some cases changes the state of a packet header bit. For such, encoder unit  812  encodes outgoing ECC bit values that may differ from the incoming ECC bit values, though using the same ECC protection scheme. 
         [0048]      FIG. 9  shows a checker/encoder  900  according to an embodiment of the invention. It receives and sends 32-bit data words. Its receive interface uses a per-byte parity scheme, with one parity bit per byte of each 32-bit (4-byte) data word. The sending interface of checker/encoder  900  uses a 7-bit SECDED ECC protection scheme. SECDED ECC is calculated per 32-bit data word. Checker/encoder  900  outputs an error signal that pulses for detected errors. 
         [0049]      FIG. 10  shows a checker/encoder  1000  according to an embodiment of the invention. It receives and sends 32-bit data words. Its receive interface uses a per-word SEC ECC scheme, with 6 bits per 32-bit data word. The sending interface of checker/encoder  1000  uses a 7-bit SECDED ECC protection scheme. SECDED ECC is calculated per 32-bit data word. Checker/encoder  1000  outputs an error signal that pulses for detected errors. 
         [0050]      FIG. 11  shows a checker/encoder  1100  according to an embodiment of the invention. It receives and 32-bit data words and sends four data bytes. The receive interface of checker/encoder  1100  uses a 7-bit per-word ECC scheme for the data, and includes a 60-bit unprotected control signal. The sending interface of checker/encoder  1100  uses a 5-bit SECDED ECC protection scheme per data byte. The sending interface also sends a 4-bit parity signal per control word. The checker/encoder  1100  also outputs a 10-bit count signal for detected errors and another 10-bit count signal for corrected errors. 
         [0051]      FIG. 12  shows an encoder  1200  according to an embodiment of the invention. It receives 32-bit data words and sends 4 separate data bytes. Its receive interface uses a per-word party scheme, with 8 bits per 32-bit data word. The sending interface of encoder  1200  uses a 2-bit parity per byte protection scheme. The encoding of parity bits on the sending interface is an interleaved mapping of the bits of the incoming data word parity. Encoder  1200  does not check for errors. 
         [0052]    Some embodiments of physical machines described and claimed herein are programmable in numerous variables, combinations of which provide essentially an infinite variety of operating behaviors. Some embodiments of hardware description language representations described and claimed herein are configured by software tools that provide numerous parameters, combinations of which provide for essentially an infinite variety of physical machine embodiments of the invention described and claimed. Methods of using such software tools to configure hardware description language representations embody the invention described and claimed. Physical machines, such as semiconductor chips; hardware description language representations of the logical or functional behavior of machines according to the invention described and claimed; and one or more non-transitory computer readable media arranged to store such hardware description language representations all can embody machines described and claimed herein. 
         [0053]    The behavior of either or a combination of humans and machines; instructions that, if executed by one or more computers, would cause the one or more computers to perform methods according to the invention described and claimed; and one or more non-transitory computer readable media arranged to store such instructions embody methods described and claimed herein. Each of more than one non-transitory computer readable medium needed to practice the invention described and claimed herein alone embodies the invention. 
         [0054]    Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. 
         [0055]    In accordance with the teachings of the invention, a computer and a computing device are articles of manufacture. Other examples of an article of manufacture include: an electronic component residing on a mother board, a server, a mainframe computer, or other special purpose computer each having one or more processors (e.g., a Central Processing Unit, a Graphical Processing Unit, or a microprocessor) that is configured to execute a computer readable program code (e.g., an algorithm, hardware, firmware, and/or software) to receive data, transmit data, store data, or perform methods. 
         [0056]    The article of manufacture (e.g., computer or computing device) includes a non-transitory computer readable medium or storage that may include a series of instructions, such as computer readable program steps or code encoded therein. In certain aspects of the invention, the non-transitory computer readable medium includes one or more data repositories. Thus, in certain embodiments that are in accordance with any aspect of the invention, computer readable program code (or code) is encoded in a non-transitory computer readable medium of the computing device. The processor or a module, in turn, executes the computer readable program code to create or amend an existing computer-aided design using a tool. The term “module” as used herein may refer to one or more circuits, components, registers, processors, software subroutines, or any combination thereof. In other aspects of the embodiments, the creation or amendment of the computer-aided design is implemented as a web-based software application in which portions of the data related to the computer-aided design or the tool or the computer readable program code are received or transmitted to a computing device of a host. 
         [0057]    An article of manufacture or system, in accordance with various aspects of the invention, is implemented in a variety of ways: with one or more distinct processors or microprocessors, volatile and/or non-volatile memory and peripherals or peripheral controllers; with an integrated microcontroller, which has a processor, local volatile and non-volatile memory, peripherals and input/output pins; discrete logic which implements a fixed version of the article of manufacture or system; and programmable logic which implements a version of the article of manufacture or system which can be reprogrammed either through a local or remote interface. Such logic could implement a control system either in logic or via a set of commands executed by a processor. 
         [0058]    Accordingly, the preceding merely illustrates the various aspects and principles as incorporated in various embodiments of the invention. It will be appreciated that those of ordinary skill in the art will be able to devise various arrangements, which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. 
         [0059]    Therefore, the scope of the invention, therefore, is not intended to be limited to the various aspects and embodiments discussed and described herein. Rather, the scope and spirit of invention is embodied by the appended claims.