Method and apparatus for providing an interface between a host device and a plurality of storage devices

• US 9,514,080 B1
• Filed: 03/17/2014
• Issued: 12/06/2016
• Est. Priority Date: 01/10/2003
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Chang, Po-Chien
• Primary Examiner(s): Dang, Khanh
• Application Number:
  US14/215,919
• Time in Patent Office: 995 Days
• Field of Search: 710/62, 710/71, 710/74, 710/302, 710/311
• US Class Current: 1/1
• CPC Class Codes: G06F 13/36 for access to common bus or bus system
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0634 by changing the state or mode of one or more devices
• CPC Class Codes: G06F 3/0661 Format or protocol conversion arrangements
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0674 Disk device

Abstract

An emulation circuit configured to emulate each of a master mode and a slave mode to provide an interface between a host device and a plurality of storage devices. The emulation circuit includes a first bus and a second bus. The emulation circuit includes a plurality of bridge circuits each configured to communicate with the host device over the first bus, communicate with a respective storage device of a plurality of storage devices over the second bus, and receive a mode select signal configured to set the bridge circuit to one of a host mode and a device mode. The bridge circuit is further configured to, if the mode select signal sets the bridge circuit to the host mode, select, based on an emulation select signal, between the master mode and the slave mode.

Claims

1. An emulation circuit configured to emulate, at different times, each of a master mode and a slave mode to provide an interface between a host device and a plurality of storage devices, the emulation circuit comprising:

a first bus configured to carry information that is formatted in accordance with a first standard;

a second bus configured to carry information that is formatted in accordance with a second standard, wherein the second standard is different from the first standard; and

a plurality of bridge circuits, each of the plurality of bridge circuits configured to

communicate, over the first bus, the information that is formatted in accordance with the first standard to the host device,

communicate, over the second bus, the information that is formatted in accordance with the second standard to a respective storage device of the plurality of storage devices,

receive a mode select signal configured to set the bridge circuit to either a host mode or a device mode, wherein when in the host mode, the bridge circuit is configured to operate as a host with respect to the respective storage device of the plurality of storage devices, and wherein when in the device mode, the bridge circuit is configured to operate as a device with respect to the host device, and

if the mode select signal sets the bridge circuit to the host mode, select, based on an emulation select signal that is independent of the mode select signal, between the master mode and the slave mode such that, while set to the host mode, the bridge circuit is further configurable between the master mode and the slave mode, wherein

in the master mode, the bridge circuit is configured to emulate a storage device configured to operate in the master mode, and

in the slave mode, the bridge circuit is configured to emulate a storage device configured to operate in the slave mode.

2. The emulation circuit of claim 1, wherein the bridge circuit is further configured to select a master/slave mode based on the emulation select signal, and wherein, in the master/slave mode, the bridge circuit is configured to emulate a storage device configured to operate in each of the master mode and the slave mode.

3. The emulation circuit of claim 1, wherein the first bus corresponds to a parallel advanced technology attachment bus and the second bus corresponds to a serial advanced technology attachment bus.

4. The emulation circuit of claim 1, wherein

when in the host mode, the bridge circuit is configured to convert serial information received via the second bus to parallel information to be provided to the first bus, and

when in the device mode, the bridge circuit is configured to convert parallel information received via the first bus to serial information to be provided to the second bus.

5. The emulation circuit of claim 1, wherein the bridge circuit includes a mode select pin configured to receive the mode select signal.

6. The emulation circuit of claim 1, wherein the mode select signal corresponds to a single digital input.

7. The emulation circuit of claim 1, wherein

the bridge circuit is configured to selectively operate in a hot plug mode in response to a hot plug signal, and

when the bridge circuit is operating in the hot plug mode, the bridge circuit is configured to determine whether the second bus has been connected to or disconnected from the bridge circuit.

8. A system comprising the emulation circuit of claim 1, and further comprising:

a second bridge circuit, external to the emulation circuit, connected between one of the plurality of bridge circuits and one of the plurality of storage devices.

9. A method of operating an emulation circuit including a plurality of bridge circuits, the emulation circuit configured to emulate, at different times, each of a master mode and a slave mode to provide an interface between a host device and a plurality of storage devices, the method comprising:

using each of the plurality of bridge circuits,

communicating, over a first bus, information that is formatted in accordance with a first standard to the host device,

communicating, over a second bus, information that is formatted in accordance with a second standard to a respective storage device of the plurality of storage devices, wherein the second standard is different from the first standard,

receiving a mode select signal configured to set the bridge circuit to either a host mode or a device mode,

when in the host mode, operating the bridge circuit as a host with respect to the respective storage device of the plurality of storage devices,

when in the device mode, operating the bridge circuit as a device with respect to the host device,

if the mode select signal sets the bridge circuit to the host mode, selecting, based on an emulation select signal that is independent of the mode select signal, between the master mode and the slave mode, such that, while set to the host mode, the bridge circuit is further configurable between the master mode and the slave mode,

in the master mode, emulating a storage device configured to operate in the master mode, and

in the slave mode, emulating a storage device configured to operate in the slave mode.

10. The method of claim 9, further comprising, using the bridge circuit:

selecting a master/slave mode based on the emulation select signal; and

in the master/slave mode, emulating a storage device configured to operate in each of the master mode and the slave mode.

11. The method of claim 9, wherein the first bus corresponds to a parallel advanced technology attachment bus and the second bus corresponds to a serial advanced technology attachment bus.

12. The method of claim 9, further comprising, using the bridge circuit:

when in the host mode, converting serial information received via the second bus to parallel information to be provided to the first bus, and

when in the device mode, converting parallel information received via the first bus to serial information to be provided to the second bus.

13. The method of claim 9, further comprising receiving the mode select signal at a mode select pin of the bridge circuit.

14. The method of claim 9, wherein the mode select signal corresponds to a single digital input.

15. The method of claim 9, further comprising, using the bridge circuit:

selectively operating in a hot plug mode in response to a hot plug signal; and

when in the hot plug mode, determining whether the second bus has been connected to or disconnected from the bridge circuit.

16. The method of claim 9, and further comprising:

connecting a second bridge circuit, external to the emulation circuit, between one of the plurality of bridge circuits and one of the plurality of storage devices.