Digi NS9215 User Manual

Page 87

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W O R K I N G W I T H T H E C P U

R0: ID code and cache type status registers

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87

You can access the cache type register by reading CP15 register R0 with the

opcode_2

field set to 1. Note this example:

MRC p15, 0, Rd, c0, c0, 1; returns cache details

Cache type
register and field
description

Dsize and Isize
fields

The Dsize and Isize fields in the cache type register have the same format, as
shown:

The field contains these bits:

Field

Description

Ctype

Determines the cache type, and specifies whether the cache supports lockdown and how it is
cleaned. Ctype encoding is shown below; all unused values are reserved.
Value: 0b1110
Method: Writeback
Cache cleaning: Register 7 operations (see “R7:Cache Operations register” on page 94)
Cache lockdown: Format C (see “R9: Cache Lockdown register” on page 98)

S bit

Specifies whether the cache is a unified cache (S=0) or separate ICache and DCache (S=1).
Will always report separate ICache and DCache for this processor.

Dsize

Specifies the size, line length, and associativity of the DCache.

Isize

Species the size, length and associativity of the ICache.

Ctype

0

S

Dsize

31

28

25 24 23

12

0

0

Isize

11 10

9

6 5

3 2 1

0

0

0

Size

M

Assoc

Len

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