Electronic device and method for selective enabling of access to configuration registers used by a memory controller
First Claim
1. An electronic device having a first plurality of terminals for external connection to a memory and a second plurality of terminals for external connection to a system bus, comprising:
- a memory controller circuit coupled to said first plurality of terminals;
configuration registers for storing configuration information for use by said memory controller circuit in performing accesses to memory via said first plurality of terminals;
a bus bridge circuit coupled to said second plurality of terminals for transferring addresses and data, and comprising;
a request logic circuit for generating, responsive to at least one of the addresses, a write request signal to said memory controller circuit signaling an impending access to at least one of said configuration registers; and
an enable circuit for enabling a write access to at least one of said configuration registers responsive to receiving a reply signal;
wherein said memory controller circuit includes a reply logic circuit for generating the reply signal responsive to the combination of the write request signal from said request logic circuit and a signal in the memory controller indicating the absence of a pending memory operation utilizing current information in at least one of said configuration registers.
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Accused Products
Abstract
An electronic device and a method of operating the same to control access to configuration registers used by a memory controller, are disclosed. The disclosed device includes a single integrated circuit microprocessor unit that includes a microprocessor core, a memory controller circuit, a bus bridge circuit, and configuration registers. The microprocessor unit is connected to external dynamic random access memory (DRAM). The memory controller circuit is operable to perform an operation utilizing current information in one or more of the configuration registers. The bus bridge circuit includes a request logic circuit for supplying a request output signaling an impending access to one or more of the configuration registers. The memory controller circuit includes a reply logic circuit for supplying a reply output back to the request logic circuit after the operation utilizing current configuration register information is completed. The request logic includes an enable circuit responsive to the reply output to then enable the impending access to the configuration registers. The device is also disclosed as in a computer system that further includes integrated circuit devices, such as a direct memory access (DMA) circuit. The microprocessor unit may also include a first level write-through cache in combination with a significantly smaller second level write-back cache. The disclosed microprocessor unit also includes circuitry for determining memory bank size and memory address type, as stored in the configuration registers.
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Citations
20 Claims
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1. An electronic device having a first plurality of terminals for external connection to a memory and a second plurality of terminals for external connection to a system bus, comprising:
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a memory controller circuit coupled to said first plurality of terminals; configuration registers for storing configuration information for use by said memory controller circuit in performing accesses to memory via said first plurality of terminals; a bus bridge circuit coupled to said second plurality of terminals for transferring addresses and data, and comprising; a request logic circuit for generating, responsive to at least one of the addresses, a write request signal to said memory controller circuit signaling an impending access to at least one of said configuration registers; and an enable circuit for enabling a write access to at least one of said configuration registers responsive to receiving a reply signal; wherein said memory controller circuit includes a reply logic circuit for generating the reply signal responsive to the combination of the write request signal from said request logic circuit and a signal in the memory controller indicating the absence of a pending memory operation utilizing current information in at least one of said configuration registers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operating an electronic device having a microprocessor, a memory controller for controlling access to a memory, and having configuration registers storing configuration information for use by the memory controller in accessing memory, comprising the steps of:
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requesting a write access to one of the configuration registers; monitoring the operation of the memory controller to detect whether a memory access is pending; after the requesting step, and responsive to the monitoring step detecting a pending memory access utilizing current information in at least one of said configuration registers blocking write access to the configuration registers; and after the requesting step, and responsive to the monitoring step detecting no pending memory access utilizing current information in at least one of said configuration registers, enabling write access to said configuration registers. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification