DHQ1ECCSECETS1SR1WH View Datasheet(PDF) - Intel

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DHQ1ECCSECETS1SR1WH

Intel® Quark SoC X1000

Intel 

Register Access Methods—Intel® Quark SoC X1000

5.0

Register Access Methods

5.1

Table 40.

There are six different common register access methods:

• Fixed I/O

• Fixed Memory

• I/O Referenced

• Memory Referenced

• PCI Configuration (Indirect - via Memory or I/O registers)

• Message Bus (Indirect - via PCI Configuration Registers)

Fixed I/O Register Access

Fixed I/O registers are accessed by specifying their 16-bit address in a PORT IN and/or

PORT OUT transaction from the CPU core. This allows direct manipulation of the

registers. Fixed I/O registers are unmovable registers in I/O space.

Fixed I/O Register Access Method Example (NSC Register)

Type: I/O Register

(Size: 8 bits)

NSC: 61h

5.2

Table 41.

Fixed Memory Mapped Register Access

Fixed Memory Mapped I/O (MMIO) registers are accessed by specifying their 32-bit

address in a memory transaction from the CPU core. This allows direct manipulation of

the registers. Fixed MMIO registers are unmovable registers in memory space.

Fixed Memory Mapped Register Access Method Example (IDX Register)

Type: Memory Mapped I/O Register

(Size: 32 bits)

IDX: FEC00000h

5.3

I/O Referenced Register Access

I/O referenced registers use programmable base address registers (BARs) to select a

range of I/O addresses that it uses to decode PORT IN and/or PORT OUT transactions

from the CPU to directly access a register. Thus, the I/O BARs act as pointers to blocks

of actual I/O registers. To access an I/O referenced register for a specific I/O base

address, start with that base address and add the register’s offset. Example

pseudocode for an I/O referenced register read is shown below:

Register_Snapshot = IOREAD([IO_BAR]+Register_Offset)

Base address registers are often located in the PCI configuration space and are

programmable by the BIOS/OS. Other base address register types may include fixed

memory registers, fixed I/O registers or message bus registers.

October 2013

Document Number: 329676-001US

Intel® Quark SoC X1000

DS

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