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System Control Coprocessor
ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 4-58
ID013010 Non-Confidential, Unrestricted Access
Figure 4-41 BTCM Region Registers
Table 4-39 shows how the bit values correspond with the BTCM Region Register.
To access the BTCM Region Register, read or write CP15 with:
MRC p15, 0, <Rd>, c9, c1, 0 ; Read BTCM Region Register
MCR p15, 0, <Rd>, c9, c1, 0 ; Write BTCM Region Register
4.2.22 c9, ATCM Region Register
The ATCM Region Register holds the base address and size of the ATCM. It also determines if
the ATCM is enabled.
The ATCM Region Register is:
• a read/write register
• accessible in Privileged mode only.
Figure 4-42 on page 4-59 shows the arrangement of bits in the register.
Base address
31 12 11 7 6 2 1 0
Reserved Size
Reserved
Enable
Table 4-39 BTCM Region Register bit functions
Bits Field Function
[31:12] Base
address
Base address. Defines the base address of the BTCM. The base address must be aligned to the
size of the BTCM. Any bits in the range [(log
2
(RAMSize)-1):12] are ignored.
At reset, if LOCZRAMA is set to:
0 =The initial base address is
0x0
.
1 =The initial base address is implementation-defined. See Configurable options on page 1-13.
[11:7] Reserved UNP on reads, SBZ on writes.
[6:2] Size Size. Indicates the size of the BTCM on reads. On writes this field is ignored. See About the
TCMs on page 8-13.
b00000 = 0KB
b00011 = 4KB
b00100 = 8KB
b00101 = 16KB
b00110 = 32KB
b00111 = 64KB
b01000 = 128KB
b01001 = 256KB
b01010 = 512kB
b01011 = 1MB
b01100 = 2MB
b01101 = 4MB
b01110 = 8MB
[1] Reserved SBZ.
[0] Enable Enables or disables the BTCM.
0 = Disabled
1 = Enabled. The reset value of this field is determined by the INITRAMB input pin.