ARM1136JF-S™ and ARM1136J-S™ Technical Reference Manual 3.3.20. c9, Data TCM Region Register

3.3.20. c9, Data TCM Region Register

The purpose of the Data TCM Region Register is to describe the physical base address and size of the Data TCM region and to provide a mechanism to enable it.

The Data TCM Region Register is:

in CP15 c9
a 32-bit read/write register
accessible in privileged mode only.

Note

ARM1136JF-S processors have a single TCM on each side, Data and Instruction. See c9, Instruction TCM Region Register for details of configuring the Instruction TCM region.

Figure 3.46 shows the arrangement of bits in the Data TCM Region Register.

Figure 3.46. Data TCM Region Register format

Table 3.93 shows the bit functions of the Data TCM Region Register.

Table 3.93. Data TCM Region Register bit functions

Bit range	Field name	Function
[31:12]	Base address	The physical base address of the TCM. The base address must be aligned to the size of the TCM. Any bits in the range [(log₂(RAMSize)-1):12] are ignored. The base address is 0 at Reset.
[11:7]	-	UNP/SBZ.
[6:2]	Size	On reads, the Size field indicates the size of the TCM, see Table 3.94.^[1]
[1]	SC	Indicates if the TCM is enabled as SmartCache: 0 = Local RAM. This is the reset value. 1 = SmartCache.
[0]	En	The En bit indicates if the TCM is enabled: 0 = TCM disabled. This is the reset value. 1 = TCM enabled.
^[1]On writes this field is ignored. For more details see Tightly-coupled memory.

Table 3.94 shows the Size field encoding value for each memory size. All other values are reserved.

Table 3.94. Size field encoding for Data TCM Region Register

Size field	Memory size
b00000	0KB
b00011	4KB
b00100	8KB
b00101	16KB
b00110	32KB
b00111	64KB

Accessing the Data TCM Region Register

Table 3.95 shows the results of attempted accesses to the Data TCM Region Register for each mode.

Table 3.95. Results of accesses to the Data TCM Region Register

Privileged read	Privileged write	User read or write
Data read	Data write	Undefined exception

To access the Data TCM Region Register you read or write CP15 with:

Opcode_1 set to 0
CRn set to c9
CRm set to c1
Opcode_2 set to 0.

For example:

MRC p15, 0, <Rd>, c9, c1, 0            ; Read Data TCM Region Register

MCR p15, 0, <Rd>, c9, c1, 0            ; Write Data TCM Region Register

Changing the Data TCM Region Register while a Prefetch Range or DMA operation is running has Unpredictable effects.

Copyright © 2002-2006 ARM Limited. All rights reserved.	ARM DDI 0211I
PDF version