US 7,257,654 B1Granted

PCI bridge device configured for using JTAG scan for writing internal control registers and outputting debug state

AssigneeAdvanced Micro Devices, Inc.

InventorsRichard W. Reeves, Austen John Hypher

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Abstract

An integrated device (e.g., an integrated PCI bridge device), having configuration registers for storing configuration values, device logic for generating internal state values based on the configuration values, and a JTAG interface configured for receiving a serial input stream and outputting a serial output stream, further includes write logic and debug read logic. The write logic is configured for writing selected portions of the serial input stream into respective selected ones of the configuration registers, based on a detected input indicating a JTAG-based override. The debug read logic is configured, in response to a detected debug mode, for outputting selected internal state values for the serial output stream, based on selection values from the serial input stream and having been stored in a prescribed at least one of the selected configuration registers.

Claims18

Dependent claims

A method in an integrated device having a JTAG interface, the method comprising:

detecting by the integrated device a prescribed device input for a JTAG-based override identifying transfer of configuration values via the JTAG interface, the integrated device further comprising a PCI bus interface, a host interface, and configuration registers storing respective stored configuration values for controlling operations of at least one of the PCI bus interface or the host interface, the host interface configured for providing access by a host device to the configuration registers;
receiving by the JTAG interface of the integrated device a JTAG clock and a serial input stream according to the JTAG clock;
detecting within the serial input stream a prescribed instruction for writing of configuration values into respective prescribed selected configuration registers;
and
selectively overwriting, based on detecting the prescribed device input and the prescribed instruction, the respective stored configuration values in the prescribed selected configuration registers of the integrated device with the configuration values from within the serial input stream for modification of the at least one of the operations of the PCI bus interface or the host interface.

2 more elements

An integrated device comprising:

a PCI bus interface;
configuration registers configured for storing respective configuration values;
a host interface configured for providing access by a host device to the configuration registers, the stored configuration values controlling operations of at least one of the PCI bus interface or the host interface;
a JTAG interface configured for receiving a JTAG clock and a serial input stream according to the JTAG clock;
and
write logic configured for detecting within the serial input stream a prescribed instruction for writing of configuration values into respective prescribed selected configuration registers, the write logic configured for selectively overwriting, based on the prescribed instruction and detection of a prescribed device input specifying a JTAG-based override identifying transfer of configuration values via the JTAG interface, selected portions of the serial input stream into the respective prescribed selected configuration registers for modification of the at least one of the operations of the PCI bus interface or the host interface.

3 more elements

Dependencies are inferred from the claim text.