82NM10 Datasheet, PDF (670/671 Pages) Intel Corporation – Intel® NM10 Family Express Chipset

Serial Peripheral Interface (SPI)
21.1.7
Note:
OPTYPE—Opcode Type Configuration Register
(SPI Memory Mapped Configuration Registers)
Memory Address:SPIBAR + 56h
Attribute:
R/W
Default Value:
0000hSize:16 bits
Entries in this register correspond to the entries in the Opcode Menu Configuration
register.
The definition below only provides write protection for opcodes that have addresses
associated with them. Therefore, any erase or write opcodes that do not use an address
should be avoided (for example, “Chip Erase” and “Auto-Address Increment Byte
Program”)
Bit
Description
15:14 Opcode Type 7 — R/W. See the description for bits 1:0
13:12 Opcode Type 6 — R/W. See the description for bits 1:0
11:10 Opcode Type 5 — R/W. See the description for bits 1:0
9:8 Opcode Type 4 — R/W. See the description for bits 1:0
7:6 Opcode Type 3 — R/W. See the description for bits 1:0
5:4 Opcode Type 2 — R/W. See the description for bits 1:0
3:2 Opcode Type 1 — R/W. See the description for bits 1:0
1:0 Opcode Type 0 — R/W. This field specifies information about the corresponding
Opcode 0. This information allows the hardware to, 1) know whether to use the address
field and, 2) provide BIOS and Shared Flash protection capabilities. The encoding of the
two bits is:
00 = No address associated with this Opcode; Read cycle type
01 = No address associated with this Opcode; Write cycle type
10 = Address required; Read cycle type
11 = Address required; Write cycle type
NOTE: This register is not writable when the SPI Configuration Lock-Down bit (SPIBAR + 00h:15)
is set.
21.1.8
Note:
OPMENU—Opcode Menu Configuration Register
(SPI Memory Mapped Configuration Registers)
Memory Address:SPIBAR + 58h
Attribute:
R/W
Default Value:
0000000000000005hSize:64 bits
Eight entries are available in this register to give BIOS a sufficient set of commands for
communicating with the flash device, while also restricting what malicious software can
do. This keeps the hardware flexible enough to operate with a wide variety of SPI
devices.
It is recommended that BIOS avoid programming Write Enable opcodes in this menu.
Malicious software could then perform writes and erases to the SPI flash without using
the atomic cycle mechanism. This could cause functional failures in a shared flash
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Datasheet