Method and system for direct access to a non-memory mapped device memory
View Patent ↗A processing system that interacts with external devices has a processor, a memory, and a controller. The memory stores templates that provide access protocol information about the external devices. When an external device is to be accessed, the operating system, which is stored in the memory, instructs the processor to perform the access to the external device. The processor puts the information about the external device on the address portion of the system bus where it is received and interpreted by the controller. The controller in turn retrieves the template for the external device as indicated by the information that was received. After retrieving the template, the controller outputs the information, in the manner indicated by the template, on an external interface bus where the external device is also coupled. The external device then responds according to the information that the controller put on the external interface bus.
1. In a processing system having a host processor coupled to a system bus, a method of operating a non-memory mapped device memory with respect to the host processor, comprising:
instructing the host processor to operate with the non-memory mapped device memory;
putting information on the system bus, wherein the information comprises both a command and an address embedded in a data stream;
retrieving the information with a memory map controller interface, wherein responsive to the information, the memory map controller interface
(i) selects the non-memory mapped device memory for a memory access if there are more than one,
(ii) downloads an appropriate access protocol template of the selected non-memory mapped device memory and performs a series of transactions to setup communication with the selected non-memory mapped device memory, wherein the appropriate access protocol template comprises a previously programmed template for each specific access type,
(iii) inserts device information into an appropriate field of a message structure on an external interface bus for transfer to the non-memory mapped device memory according to the information and the template; and
operating an actual data transfer with the non-memory mapped device memory according to the device information, wherein the information comprises a mode of operation, chip select, access type, and an address.
2. The method of claim 1 , wherein the non-memory mapped device memory comprises a memory of an LCD controller, co-processor, peripheral device, graphic accelerator, imaging device or simply any peripheral with addressable registers or memory.
3. The method of claim 1 , wherein the system bus contains an address bus.
4. The method of claim 1 , wherein the information comprises a method of operation of the device.
5. The method of claim 4 , wherein the method of operation is selected from a group consisting of read and write.