JPH05189363A - Bus controller - Google Patents

Abstract

PURPOSE:To always execute proper bus arbitration by providing a bus arbitration means giving the using right of the bus to a device requiring the using of the bus or an extension bus control means. CONSTITUTION:When both a device 102 and an extension device A 105 (an extension bus control means 109) require the using of the bus 101 at the same time, the bus arbitration means 114 recognizes that the extension device A 105 requires the using of the bus 101 through the extension bus control means 109 with a bus using requiring person signal 111 and gives the using permission of the bus to the extension bus control means 109. When both the device 102 and the extension device B 107 (the extension bus control means 109) requires the using of the bus 101 at the same time, the bus arbitration means 114 recognizes that the extension device B 107 requires the using of the bus 101 through the extension bus control means 109 with the bus using requiring person signal 111 and gives the using permission of the bus to the device 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus control device in an information processing device in which a plurality of devices are connected on a plurality of buses having different data transfer protocols.

[0002]

2. Description of the Related Art In many current information processing apparatuses, a plurality of devices share a plurality of buses for processing, and a device can access another device through a plurality of buses. .. In such an information processing apparatus, controlling the data transfer between devices efficiently through a plurality of buses is one of the important issues in achieving high speed processing. An example of the above-described conventional bus control device will be described below with reference to the drawings.

FIG. 2 is a block diagram showing an example of a bus controller which has been widely used in the past. In FIG. 2, 2
Reference numeral 01 is a bus, 202 is a device connected to the bus 201, 203 is a use request signal of the bus 201 output by the device 202, 204 is an expansion bus having a data transfer protocol different from that of the bus 201, and 205 is an expansion bus 204. The connected expansion device A, 206 is a use request signal of the expansion bus 204 output by the expansion device A 205, 2
Reference numeral 07 is an expansion device B connected to the expansion bus 204, 208 is a use request signal of the expansion bus 204 output from the expansion device B 207, 209 is an expansion bus control means, 2
Reference numeral 10 is a use request signal of the bus 201 output from the extension bus control unit 209, 211 is a use permission signal of the extension bus 204 to the extension device A 205, 212 is a use permission signal of the extension bus 204 to the extension device B 207, 21
Reference numeral 3 is a bus arbitration unit, 214 is a use permission signal of the bus 201 to the device 202, and 215 is an expansion bus control unit 2.
09 is a bus 201 use permission signal. The operation of the bus control device configured as described above will be described below.

The expansion bus control unit 209 permits the expansion device A 205 to use the expansion bus 204 and requests the bus arbitration unit 213 when only the expansion device A 205 requests the use of the expansion bus 204 and the bus 201. Request the use of bus 201. In the expansion bus control means 209, only the expansion device B207 is connected to the expansion bus 2
04 and the use of the bus 201 are requested, the expansion device B 207 is permitted to use the expansion bus 204 and the bus arbitration unit 213 is requested to use the bus 201. Further, when both the expansion device A205 and the expansion device B207 request to use the expansion bus 204 and the bus 201 at the same time, the expansion bus control means 209 determines whether the expansion device A205 or the expansion device B207 is in accordance with a predetermined priority order. To permit the use of the expansion bus 204 and the bus arbitration means 2
13 is requested to use the bus 201. In the bus arbitration unit 213, only the expansion bus control unit 209 is connected to the bus 201.
When the use of the bus 201 is requested, the extension bus control unit 209 is permitted to use the bus 201. Bus arbitration means 2
13 permits the device 202 to use the bus 201 when only the device 202 requests the use of the bus 201. Further, the bus arbitration unit 213 is configured so that both the expansion bus control unit 209 and the device 202 can simultaneously operate on the bus 20.
When the use of the bus 201 is requested, the use of the bus 201 is permitted to either the expansion bus control means 209 or the device 202 according to a predetermined priority (eg, "Nikkei Data Pro Microprocessor", 1990, 8). Mon, Nikkei BP, MC1-813
591-MC1-813-595).

[0005]

However, optimal bus arbitration of the device cannot be performed with the above-mentioned configuration. For example, in the case where the device, the expansion device A, and the expansion device B are used in the descending order of priority in the use of the bus, the expansion bus control unit and the device use the bus in the order of priority. , The bus arbitration unit is designed to increase the priority of the device, and the expansion bus control unit is designed to increase the priority of the expansion device A and the expansion device B in using the bus. At times, the relationship between the device requesting the use of the bus and the device permitted to use the bus is as shown in (Table 1).

[0006]

[Table 1]

In this case, when both the device and the expansion device A, that is, both the device and the expansion bus control means simultaneously request the use of the bus, the device is expanded device A.
As a result, the bus will be used with priority over that of, and optimal bus arbitration will not be performed. On the contrary, if the bus arbitration means is designed so that the priority of the bus usage of the expansion bus control means and the device is high, the device requesting the use of the bus and the bus usage of the bus are designed. The relationship of allowed devices is as shown in (Table 2),

[0008]

[Table 2]

When both the device and the expansion device B request the use of the bus at the same time, that is, both the device and the expansion bus control means, the expansion device B preferentially uses the bus over the device. Not done.

That is, in the configuration shown in FIG. 2, the expansion device A and the expansion device B for the device are used.
Appropriate bus arbitration is performed only when the priorities in using the buses are high or low.

In order to solve the above-mentioned problems, the present invention is always optimized by dynamically changing the priority order of the device and the expansion bus control means according to the device requesting the use of the bus and the expansion device. It is an object of the present invention to provide a bus control device that guarantees that a proper bus arbitration is performed.

[0012]

In order to achieve the above object, a bus control device of the present invention comprises at least one device connected to a bus and at least one extension having a data transfer protocol different from that of the bus. A bus, a plurality of expansion devices connected to the expansion bus, a use request signal of the bus and the expansion when the expansion device is connected to both the bus and the expansion bus and the expansion device requests the use of the bus At least one extension bus control means for outputting a bus use requester signal indicating which one of the devices requests the use of the bus; and the device or the extension bus control means requests the use of the bus The bus use right to one of the device requesting the use of the bus or the expansion bus control means. Those having a structure of bus arbitration means for arbitrating as.

[0013]

According to the present invention, according to the above configuration, the expansion bus control means requests the bus use to the bus arbitration means when the expansion device requests the use of the bus, and which expansion device requests the use of the bus. The bus arbitration means is notified of a bus use requester signal indicating whether the bus is being used. Then, the bus arbitration unit determines the priority of the device requesting the use of the bus and the expansion bus control unit based on the bus use requester signal, and gives the bus use right to the device having the higher priority.

As a result, if the priority of the use of the expansion device requesting the use of the bus through the expansion bus control means is higher than that of the device, the bus arbitration means instructs the expansion bus control means to use the device. If the priority of the use of the bus of the expansion device requesting the use of the bus through the expansion bus control means is lower than that of the device,
Since the bus arbitration unit can give the device permission to use the bus in preference to the expansion bus control unit, optimum bus arbitration is always performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bus controller according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a bus controller according to an embodiment of the present invention. In FIG. 1, 101 is a bus, 102 is a device connected to the bus 101,
Reference numeral 103 is a use request signal of the bus 101 output by the device 102, 104 is an expansion bus having a data transfer protocol different from that of the bus 101, 105 is an expansion device A connected to the expansion bus 104, and 106 is an expansion device A10.
5 outputs a request signal for using the expansion bus 104, 107 is an expansion device B connected to the expansion bus 104, 10
8 is a use request signal of the expansion bus 104 output from the expansion device B 107, 109 is an expansion bus control unit, 110 is a use request signal of the bus 101 output from the expansion bus control unit 109, 111 is a bus use requester signal, and 112 is A use permission signal of the expansion bus 104 to the expansion device A105,
113 is an expansion bus 104 for the expansion device B107
Use permission signal, 114 is bus arbitration means, 115 is a use permission signal of the bus 101 to the device 102, 116
Is a use permission signal of the bus 101 to the expansion bus control means 109.

The operation of the bus control device configured as described above will be described below with reference to FIG.

The expansion bus control means 109 permits the expansion device A 105 to use the expansion bus 104 when only the expansion device A 105 requests the use of the expansion bus 104 and the bus 101, and the bus arbitration means 114. Requesting the use of the bus 101 and using the bus use requester signal 111 to notify that the expansion device A 105 requests the use of the bus. Further, in the expansion bus control means 109, only the expansion device B107 has the expansion bus 1
04 and the use of the bus 101 are requested, the use of the extension bus 104 is permitted to the extension device B107, the use of the bus 101 is requested to the bus arbitration means 114, and the bus use requester signal 111 is used. Then, the expansion device B107 notifies that the use of the bus is requested. Further, when both the expansion device A105 and the expansion device B107 request the use of the expansion bus 104 and the bus 101 at the same time, the expansion bus control means 109 determines whether the expansion device A105 or the expansion device B107 is in accordance with a predetermined priority order. To the bus arbitration unit 114 and request the bus arbitration unit 114 to use the bus 101, and the bus use requester signal 111 is used to request either the expansion device A 105 or the expansion device B 107 to use the bus. Notify if you are doing. The bus arbitration unit 114, when only the expansion bus control unit 109 requests the use of the bus 101,
The extension bus control unit 109 is permitted to use the bus 101. Further, the bus arbitration unit 114, when only the device 102 requests the use of the bus 101, the device 10
2 is permitted to use the bus 101. Further, the bus arbitration unit 114 includes the expansion bus control unit 109 and the device 1.
02 simultaneously requests the use of the bus 101, the bus use requester signal 11 indicates the priority of use of the bus between the device 102 and the expansion bus control means 109.
Bus 101 is decided based on 1 and has a higher priority.
Allow the use of.

As described above, according to the present embodiment, for example, when the device 102, the expansion device A105, and the expansion device B107 have the highest priority in use of the bus, the expansion device A105, the device 102, and the expansion device B107 are in descending order. For the optimum bus arbitration, the expansion bus control means 109 is designed to give priority to the expansion device A 105, and the bus arbitration means 114 is designed to perform bus arbitration based on (Table 3). Is guaranteed.

[0020]

[Table 3]

As a result, when both the device 102 and the expansion device A 105, that is, both the device 102 and the expansion bus control means 109 simultaneously request the use of the bus 101, the bus arbitration means 114 expands by the bus use requester signal 111. Since the device A 105 recognizes that the use of the bus 101 is requested through the extension bus control unit 109, the use permission of the bus can be given to the extension bus control unit 109, and optimal bus arbitration is performed. Further, both the device 102 and the expansion device B 107, that is, the device 102 and the expansion bus control means 109.
When both of them request the use of the bus 101 at the same time, the bus arbitration unit 114 recognizes that the expansion device B 107 requests the use of the bus 101 through the expansion bus control unit 109 by the bus use requester signal 111. , The use of the bus can be given to the device 102, and optimal bus arbitration is performed.

In this embodiment, the number of devices and the number of expansion bus control means are each one, but there may be a plurality of each. Further, in this embodiment, the expansion bus control means 10
9 is a bus use request signal 110 and a bus use requester signal 1
11 is used to notify the bus arbitration means 114 which of the expansion device A and the expansion device B is requesting the use of the bus, but instead of the bus use request signal 110 and the bus use requester signal 111. Using the expansion device A bus use request signal indicating that the expansion device A requests the use of the bus and the expansion device B bus use request signal indicating that the expansion device B requests the use of the bus, The bus arbitration unit 114 may be notified which of the expansion device A and the expansion device B requests the use of the bus.

[0023]

As described above, according to the present invention, when the expansion device is connected to both the bus and the expansion bus and requests the use of the bus, either the bus use request signal or the expansion device requests the use of the bus. At least one expansion bus control means for outputting a bus usage requestor signal indicating whether the bus usage requester signal is obtained from the expansion bus control means when the device or the expansion bus control means requests the use of the bus. The optimum bus arbitration can always be performed by providing the bus arbitration unit that arbitrates to give the right to use the bus to one of the device requesting the use of the bus or the expansion bus control unit. ..

[Brief description of drawings]

FIG. 1 is a configuration diagram of a bus control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional bus control device.

[Explanation of symbols]

 101 bus 102 device 103 bus use request signal 104 expansion bus 105 expansion device A 106 bus use request signal 107 expansion device B 109 expansion bus control means 110 bus use request signal 111 bus use requester signal 112 bus use permission signal 113 bus use permission Signal 115 Bus use permission signal 116 Bus use permission signal

Claims (1)

[Claims] 1. At least one device connected to the bus, at least one expansion bus having a data transfer protocol different from that of the bus, a plurality of expansion devices connected to the expansion bus, and the bus. And a bus use request which is connected to both the extension bus and which indicates which of the bus use request signal and the extension device requests the use of the bus when the extension device requests the use of the bus. At least one expansion bus control means for outputting a user signal, and requesting the use of the bus based on the bus use requester signal when the device or the expansion bus control means requests the use of the bus Device or one of the expansion bus control means
A bus control device, comprising bus arbitration means for arbitrating the right to use the bus.