JPH07134686A - Bus switching device and bus control system for hierarchical connection bus - Google Patents

Abstract

PURPOSE:To prevent access speed from being decreased due to bus switching overhead at a bus connection part by providing a means which directly sends out transfer data and a clock signal fetched in from a bus to which the module of an output origin is connected to a bus to which a transfer destination module is connected. CONSTITUTION:The transfer destination module 3 and a connected bus B can be recognized by decoding an access address at a data transfer origin module 2, and it is switched to the transfer speed of the bus B, and data and a clock are sent out. A bus using right of another hierarchy required as a transfer route can be acquired simultaneously with the bus A to which its own module 2 is connected. In a bus switching device 1, supplied data and clock are passed through the inside of the bus switching device in through fashion, and it is permitted to run on the bus B of another hierarchy as it is. Therefore, the transfer destination module 3 can receive the data and the clock as it is even when an access destination is located on the bus of another hierarchy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus used in an information processing device such as a personal computer, a workstation, an office computer or the like.

[0002]

2. Description of the Related Art Conventionally, a bus for an information processing apparatus, which is a method of multiplexing an address and data, is divided into an address transfer transaction and a data transfer transaction, each of which independently completes a read operation. An example of a bus having a split transfer means and a so-called source synchronous transfer means for performing transfer at a timing synchronized with a source clock supplied from an output source at the time of data transfer is, for example, IEE, Draft Standard P896. .1R / D8.5: Future Bus Plus Logical Layer Specifications (1991) pp. 63-104 (IEEE D
rough Standard P896.1R / D8.
5: Futurebus + Logical Layer
r Specifications, IEEE Com
putter Society Press (1991)
The Future Bus Plus described in PP 63-104) is known.

In recent years, buses have become an important technique for improving system performance, and higher performance is required. The source synchronous transfer method is being adopted as one of the effective methods to meet the problem of the high speed bus. The source-synchronous transfer method has advantages that the clock distribution skew is small and the transfer frequency can be easily increased.

On the other hand, a CPU bus, a system bus, an IO bus, etc. are separated via a bus adapter from conflicting requirements of tracking CPU performance and compatibility of existing IOs, multi-line and various IO connection requirements, and the like. , Hierarchical so-called buses are progressing.

[0005]

In a system in which these conventional techniques are combined, that is, in a bus system in which source synchronous buses (including one-to-one paths and channels) are hierarchically connected, modules on the same bus are used. Transfers between them are performed at high speed by the source synchronous transfer method, but transfer across bus layers has the problem that the original advantages of the source synchronous transfer method cannot be fully utilized due to the overhead of bus conversion at the bus connection. there were. An object of the present invention is to prevent a decrease in access speed due to a bus conversion overhead or the like in a bus connection part in an information processing system using hierarchically connected source synchronous buses,
It is to provide a high-speed bus control system and its bus system that can fully utilize the original advantages of the source synchronous transfer system.

[0006]

In order to achieve the above object, the present invention provides a bus system adopting a source synchronous transfer system (including one-to-one paths and channels) in a hierarchically connected bus system, in which: The means (1) to (3) are provided.

(1) In the data transfer source module,
Means are provided for recognizing the transfer destination module and the bus to which it is connected by decoding the access address, converting the transfer speed to the transfer speed of the bus, and transmitting the data and clock.

(2) In the data transfer source module,
In addition to the bus to which the module itself is connected, a means for simultaneously acquiring the bus use right of another layer required as a transfer path is provided.

(3) In the bus converter, there is provided means for allowing the data and the transfer clock signal supplied from the data transfer source module to pass through the inside of the bus converter through and to be flowed on the bus of another layer as they are.

[0010]

According to the above means, even if the access destination is on another hierarchical bus, the slave module can receive the data and the transfer clock signal supplied by the data transfer source module as they are, so that the bus hierarchy can be crossed. Source synchronous transfer method can be applied. That is,
Conventionally, a bus converter temporarily latches data and then
The processing that started the data transfer to the next layer can be realized as the source synchronous transfer similar to the bus in the same layer by only delaying the time corresponding to the internal delay of the bus conversion device, and the transfer speed is improved. Can be made.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing an internal configuration of a bus converter for connecting source-synchronous buses of a bus system according to the present invention and a bus master module connected to each source-synchronous bus. FIG. 2 shows the present invention as a source-synchronous bus. A system configuration diagram showing an application example in which the same is applied to a hierarchically connected bus system, FIG. 3 and FIG. 4 are applications of the present invention applied to a system in which a source synchronous bus and a source synchronous channel (one-to-one) are hierarchically connected. System configuration diagram showing an example,
5 is a system configuration diagram showing an application example in which the present invention is applied to a system in which source synchronous channels are hierarchically connected, FIG. 6 is an access timing chart diagram of a bus system according to the present invention, and FIG. 7 is a bus system according to the present invention. FIG. 8 is a flowchart of an example of the operation, and FIG. 8 is an access time chart for each transfer destination module.

In FIG. 1, 1 is a bus converter for connecting the source-synchronous buses of this embodiment, 2 is a bus master module connected to one of the layered source-synchronous buses (A bus), and 3 is a bus master module. Bus master modules 4 to 8 connected to the other layered source synchronous bus (B bus) are components of the bus master module 2,
4 is an input data buffer, 5 is an output data buffer, 6
Is a transmission clock control unit, 7 is a transmission control unit, 8 is a bus arbiter for arbitrating the A bus, 9 and 10 are bidirectional input / output drivers, 11 to 24 are components inside the bus converter 1, and 11 is an input. A data buffer, 12 is an input data buffer, 13 is a transmission clock control unit, 14 is a bus right control unit for the A bus, 15 is a transmission / reception control unit, 16 is a bus arbiter for arbitrating the B bus, 17, 18, 19 , And 20 are bidirectional input / output drivers, 21, 22, 23 and 24 are selectors, 25 to 31 are constituent elements of the bus master module 3, 25 is an input data buffer, and 26 is an input data buffer.
Is an output data buffer, 27 is a transmission clock controller, 2
Reference numeral 8 is a transmission control unit, 29 is a bus right control unit for the B bus, 30 and 31 are bidirectional input / output drivers, 32 is a clock line of the A bus which is a source synchronous bus, and 33 is a data line of the A bus (also address). Included), 34 is a clock line of B bus which is a source synchronous bus, 35 is a data line of B bus (including address), 36 is an arbitration control signal of A bus, 37 is an arbitration control signal of B bus, 38
Is a source crossover source synchronous transfer request signal for which the bus master module 2 is the master, 37 is an arbitration control signal for the B bus, 39 is a hierarchical crossover source synchronous transfer request signal for which the bus master module 3 is the master, and 40 is inside the bus converter 1. Control register, 41 is a hierarchy crossover source synchronous transfer permission signal in which the bus master module 2 is a master, 42 is a hierarchy crossover source synchronous transfer permission signal in which the bus master module 3 is a master, 43 is an access address decoder, 44 corresponds to an access destination module A clock speed converter, 45 is an address-specific module table for associating an access address with an access destination module, 46 is an access address decoder, 47 is a clock speed converter corresponding to an access destination module, 48
Is an address-specific module table that associates access addresses with access destination modules. In FIG. 2, 101 is a processor, 102 is a processor / main memory interface device, 103 is a main memory, 1
Reference numeral 04 is a system bus which is a source synchronous bus, 105 and 106 are IO buses which are source synchronous bus, 111
Is a bus converter for connecting the system bus 104 and the IO bus 105, 112 is a bus converter for connecting the system bus 104 and the IO bus 106, 10
Reference numerals 7, 108, 109 and 110 are IO adapter devices. In FIG. 3, reference numeral 113 is a channel for transferring between the processor and the main memory device interface device 102 and the IO bus 105, 114 is a channel for transferring between the processor and main memory device interface device 102 and the IO bus 106, and 115 is a channel. A bus conversion device for connecting the channel 113 and the IO bus 105, and a bus conversion device 116 for connecting the channel 114 and the IO bus 106. In FIG. 4, 117 is the system bus 10.
A channel for transferring data between 4 and the IO adapter 107, 11
8 is a channel for transferring between the system bus 104 and the IO adapter 108, 119 is a channel for transferring between the system bus 104 and the IO adapter 109, 120 is a channel for transferring between the system bus 104 and the IO adapter 110, and 121 is A conversion device connecting the system bus 104 and the channels 117 and 118, and a conversion device 122 connecting the system bus 104 and the channels 119 and 120. In FIG. 5, 123 and 124 are channels,
125 is a channel for transferring data between the channel 123 and the IO adapter 107, 126 is a channel for transferring data between the channel 123 and the IO adapter 108, and 127 is channel 1
24, a channel for transferring between the IO adapter 109 and 24
28 is a channel for transferring between the channel 124 and the IO adapter 110, and 129 is a channel 123 and a channel 12.
A converter connecting 5 and 126, and a converter connecting 130 to the channels 124 and 127 and 128. In FIG. 6, 601 to 608 are time charts at the time of data transfer from the bus master module 2 to the bus master module 3, 601 is data of the A bus observed at the terminal of the master module 2, and 602 is observed at the terminal of the master module 2. A bus clock, 603
Is the data of the A bus observed at the terminal of the bus converter 1, 6
04 is the A bus clock observed at the terminal of the bus converter 1, 605 is B bus data observed at the terminal of the bus converter 1, 606 is the B bus clock observed at the terminal of the bus converter 1, and 607 is Is the data of the B bus observed at the terminal of the master module 3, 608 is the master module 3
This is the clock of the B bus observed at the terminal. In FIG. 8, 801, 802, 803 and 804 are transfer time charts from the processor / main memory interface 102 to the IO adapter 107, which is a module on the IO bus 105, and 801 is observed at the terminals of the processor / main memory interface 102. Data waveform, 802, a clock waveform observed at a terminal of the processor / main memory interface 102, 803, a data waveform observed at a terminal of the IO adapter 107, 804: IO adapter 107
Waveforms of clocks observed at the terminals of 805, 806, 8
Reference numerals 07 and 808 are transfer time charts from the processor / main memory interface 102 to the IO adapter 109, which is a module on the IO bus 106, 805 is a waveform of data observed at the terminals of the processor / main memory interface 102, and 806 is a processor.・ Clock waveform observed at the main memory interface 102 terminal, 80
7 is a waveform of data observed at the terminal of the IO adapter 109, and 808 is a waveform of clock observed at the terminal of the IO adapter 109. First, consider a system configuration in which the source-synchronous buses of FIG. 2 are hierarchically connected. When the processor 101 performs processor IO access (PIO) and direct memory access (DMA), the source synchronous bus passes through a hierarchically connected path. Here, the processor and main memory device interface device 102 which are the components of FIG. 2, the system bus 104 which is a source synchronous bus, the bus converter 111 for connecting the system bus 104 and the IO bus 105, and the source synchronous IO. Each of the bus 105 and the IO adapter 107 has a structure such as the bus master module 2, the source synchronous bus (A bus), the bus converter 1, the source synchronous bus (B bus), and the bus master module 3 in FIG.

When the PIO access is activated from the bus master module 2 side, the bus master module 2
Determines which module the transfer address is accessed by using the decoder 43 and the address-specific module table 45. Here, the contents of the address-specific module table 45 are set by PIO access. As a result, it is possible to transfer the source synchronously across layers.
When it is determined to be for a module on the bus, the control signal 38 is used to make a source synchronous transfer request across the layers to the bus conversion device 1. Receiving this, the bus conversion device 1 acquires the bus right of the B bus, and then transmits the layer crossing source synchronous transfer permission to the bus master module 2 using the control signal 41. The master module 2 which has received the layer-to-layer source synchronous transfer permission,
Thus, the transfer operation matching the speed of the B bus connected to the module 3 is started. The output data sent from the output data buffer 5 is output from the bidirectional input / output buffers 9 and 10 onto the A bus together with the source clock generated by the transmission clock controller 6. The bus conversion device 1 takes in transfer data and a clock from the bidirectional input / output buffers 17 and 18. In the layer-to-layer source synchronous transfer mode, unlike the normal access, the bus conversion device 1 does not store the data in the internal input data buffer 11 but directly transmits it to the B bus through the selector 21 and the bidirectional input / output buffer 19. . Similarly, for the clock, the B bus 3 is passed through the selector 23 and the bidirectional input / output buffer 20.
4 is output. The master module 3 uses the clock fetched from the bidirectional input / output buffer 31 for the data fetched from the bidirectional input / output buffer 31 regardless of whether the mode is the source-to-hierarchical source synchronous transfer mode. , And completes a series of operations from the master module 2 to the master module 3. In this case, the transfer pitch of the source-synchronous transfer across layers is different depending on the performance of the IO bus. FIG. 8 shows the difference between the transfer using the system bus 104 and the IO bus 105 and the transfer using the system bus 104 and the IO bus 106. During hierarchical source-to-layer synchronous transfer using the system bus 104 and the IO bus 105, transfer between IO adapters on the IO bus 105 is possible. On the other hand, system bus 104 and IO bus 1
During the source synchronous transfer across layers using 06, IO bus 1
The transfer of IO adapters on 05 is possible. This operation is shown in a flowchart in FIG. (After the start, 701: an access request is generated in module 2, 70
2: Demand source synchronous transfer across layers to the bus conversion device 1; 703: Bus conversion device 1 requests bus right from B bus arbiter; 704: Waits until B bus bus right is acquired 705: From bus conversion device 1 Sending a layer-over-source synchronization transfer permission signal to module 2, 706: module 2 sends out transmission data and clock, 707: bus conversion device 1 causes data and clock sent by module 2 to simply pass through B bus, 708 : The module 3 takes in the clock and data on the B bus internally, latches the data, and ends) Conversely, when performing the DMA access that is activated from the bus master module 3 side, the bus master module 3
Decoder 46 and address-specific module table 48
It is determined by which module the transfer address is accessed. As a result, the control signal 39 is used to issue a layer-to-layer source synchronous transfer request to the bus conversion device 1 when it is determined that the module is on a module on the B bus capable of layer-to-layer source synchronous transfer. The bus conversion device 1 having received the request acquires the bus right of the A bus by using the arbitration control signal 36 of the A bus, and then transmits the hierarchy crossing source synchronous transfer permission to the bus master module 3 by using the control signal 42. The master module 3 which has received the source-to-tier source synchronous transfer permission starts the transfer operation according to the speed of the A bus to which the module 2 is connected, by the clock speed converter 47. Output data buffer 2
The output data sent from 6 is the transmission clock control unit 2
It is output from the bidirectional input / output buffers 30 and 31 on the B bus together with the source clock generated in 8. The bus conversion device 1 takes in transfer data and a clock from the bidirectional input / output buffers 19 and 20. In the layer-to-layer source synchronous transfer mode, unlike the normal access, the bus conversion device 1 does not store the data in the internal input data buffer 12 but directly transmits it to the A bus through the selector 22 and the bidirectional input / output buffer 17. . Similarly, the clock is output to the A bus 32 via the selector 24 and the bidirectional input / output buffer 18. The master module 2 uses the clock taken in from the bidirectional input / output buffer 10 for the data taken in from the bidirectional input / output buffer 9 regardless of whether the mode is the source synchronous transfer mode across layers.
Latches to the input data buffer 4, and the master module 3
To the master module 2 is completed.
In both PIO and DMA, read access is based on split transfer in which a read activation cycle and a response data cycle can be divided by bus arbitration. Therefore, the PIO read response is an access activated from the bus master module 3, and the DMA read response is an access activated from the bus master module 2. A time chart of access from the bus master module 2 to the bus master module 3 is shown in FIG. The waveforms of the data and clock signals observed at the terminals of the bus master module 3 of the B bus are the same as those of the waveforms observed at the terminals of the master module 2 of the A bus, showing the A bus propagation delay, the internal delay of the bus converter, and the B bus propagation delay. It is reported with a total time delay. In the present embodiment, an application example of two layers is shown, but it does not matter even if the layer crossing source synchronization method of the present invention is applied to three or more layers. As for the system configuration, when the upper side is a channel and the lower side is a bus as shown in FIG. 3, or when the upper side is a bus and the lower side is a channel as shown in FIG. 4, both the upper side and the lower side are as shown in FIG. It may be a channel, but each operation omits the processing to acquire the bus right in advance when the other side of the activation bus master module is the channel across the bus conversion device among the above controls. Becomes

As described above, according to the method of this embodiment, when the buses or channels adopting the source synchronization method are hierarchically connected, even if the access destination is on another hierarchical bus, the data transfer source module Since the slave side module can receive the data and the transfer clock signal supplied by the device as they are, the source synchronous transfer method can be applied across the bus hierarchy. That is, the conventional process in which data is temporarily latched in the bus conversion device and then data transfer is started to the next hierarchical bus is delayed by the internal delay of the bus conversion device, and the same processing as in the bus in the same hierarchy is performed. This can be realized as source synchronous transfer, and has the effect of improving the transfer speed.

[0015]

According to the present invention, even if the access destination is on another hierarchical bus, the slave module can receive the data and the transfer clock signal supplied by the data transfer source module as they are. Source synchronous transfer method can be applied across layers. That is, the conventional process in which data is temporarily latched in the bus conversion device and then data transfer is started to the next hierarchical bus is delayed by the internal delay of the bus conversion device, and the same processing as in the bus in the same hierarchy is performed. This can be realized as source synchronous transfer, and has the effect of improving the transfer speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an internal configuration of a bus conversion device for connecting source-synchronous buses of a bus system according to the present invention and a bus master module connected to each source-synchronous bus.

FIG. 2 is a system configuration diagram showing a configuration example in which the present invention is applied to a bus system in which source synchronous buses are hierarchically connected.

FIG. 3 is a system configuration diagram showing a configuration example in which the present invention is applied to a system in which a source synchronization bus and a source synchronization channel are hierarchically connected.

FIG. 4 is a system configuration diagram showing a configuration example in which the present invention is applied to a system in which a source synchronization bus and a source synchronization channel are hierarchically connected.

FIG. 5 is a system configuration diagram showing a configuration example in which the present invention is applied to a system in which source synchronization channels are hierarchically connected.

FIG. 6 is an access timing chart of the bus system according to the present invention.

FIG. 7 is a flowchart of an example of operation of the bus system according to the present invention.

FIG. 8 is an access time chart for each transfer destination module according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bus conversion device for connecting source-synchronous buses, 2 ... Bus master module connected to one layered source-synchronous bus (A bus), 3 ... Other layered source-synchronous bus Bus master module connected to (B bus), 4 ... Input data buffer, 5 ... Output data buffer, 6 ... Transmission clock control unit, 7 ... Transmission control unit, 8 ... Bus arbiter for performing bus arbitration for A bus, 9, 10 ... bidirectional input / output driver, 11 ... input data buffer, 12 ... input data buffer, 13 ... transmission clock control unit, 14 ... A bus bus right control unit, 15 ... transmission / reception control unit, 16 ... B bus bus Bus arbiter for arbitration, 17, 18, 19, 20 ... Bidirectional input / output driver, 21, 22, 23, 24 ... Selector, 25 ... Input data buffer, 2 Output data buffer, 27 ... Transmission clock control unit, 28 ... Transmission control unit, 29 ... Bus right control unit of B bus, 30, 31 ... Bidirectional input / output driver, 32 ... Clock of A bus which is a source synchronous bus Line, 33 ... A bus data line (including address), 34 ... B bus clock line that is a source-synchronous bus, 35 ... B bus data line (including address), 36 ... A bus arbitration control signal , 37 ... B bus arbitration control signal, 38 ... Hierarchical source transfer request and permission signal for which bus master module 2 is a master, 37 ... B bus arbitration control signal, 39 ... Hierarchical source for which bus master module 3 is a master Synchronous transfer request and permission signal, 40 ... Control inside bus converter 1.

Claims (7)

[Claims] 1. A bus for an information processing apparatus, wherein a plurality of buses of a source synchronous transfer system for performing data transfer at a timing synchronized with a clock signal supplied from a data output source are connected via a bus converter (bus adapter). In a hierarchically connected bus system, the transfer data and clock signals fetched from the first bus to which the transfer data output source module is connected are transferred to the bus converter on the second bus to which the transfer destination module is connected. A bus conversion device for a hierarchical connection bus, characterized in that it comprises means for sending directly to the bus. 2. A bus system in which a plurality of buses of a source synchronous transfer system are hierarchically connected via the bus converter of claim 1, wherein the data and clock supplied by a transfer data output source module are converted to the bus. A bus control method, wherein a device takes in from the first bus, sends it directly to the second bus, and transmits it to a transfer destination module to perform a source synchronous transfer method across the bus hierarchy. 3. The bus system according to claim 2, wherein the module of the transfer data output source is provided with means for simultaneously acquiring the bus use right of the first bus and the second bus. After taking the bus right of the second level,
A bus control method characterized by performing source synchronous transfer across layers. 4. The bus system according to claim 2, wherein the transfer data output source module decodes the access destination address to recognize the access destination module and the bus to which the access destination module is connected. ,
A bus interface device for a source synchronous bus, which is provided with means for converting a transfer rate of data and a clock according to a speed of a bus connected to an access destination module. 5. A bus system comprising the bus interface device according to claim 4 on the first bus according to claim 2 or 3, wherein a module of a transfer data output source on the first bus is a transfer destination. A bus control method, wherein data and clock are transmitted according to the speed of the second bus connected to the module, and the source synchronous transfer method is performed across the bus hierarchy. 6. A hierarchical cross-source synchronous transfer system, wherein the bus control system of claim 2, claim 3, or claim 5 is applied to buses of three or more layers. 7. The bus system according to claim 2, claim 4, claim 5, or claim 6, wherein at least one or more of the hierarchical buses are connected in a one-to-one relationship. Bus system characterized by