
W O R K I N G W I T H T H E C P U
R7:Cache Operations register
94
Hardware Reference NS9215
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
R 7 : C a c h e O p e r a t i o n s r e g i s t e r
Register R7 controls the caches and write buffer. The function of each cache
operation is selected by the
opcode_2
and
CRm
fields in the
MCR
instruction that
writes to CP15 R7. Writing other
opcode_2
or
CRm
values is
UNPREDICTABLE.
Reading from R7 is
UNPREDICTABLE
, with the exception of the two test and clean
operations (see “Cache operation functions” on page 95 and “Test and clean
DCache instructions” on page 96).
Write instruction
Use this instruction to write to the Cache Operations register:
MCR p15, opcode_1, Rd, CRn, CRm, opcode_2
Cache functions
This table describes the cache functions provided by register R7.
Function
Description
Invalidate cache
Invalidates all cache data, including any dirty data.
Invalidate single entry using either index or
modified virtual address
Invalidates a single cache line, discarding any dirty data.
Clean single data entry using either index or
modified virtual address
Writes the specified DCache line to main memory if the
line is marked valid and dirty. The line is marked as not
dirty, and the valid bit is unchanged.
Clean and invalidate single data entry using
wither index or modified virtual address.
Writes the specified DCache line to main memory if the
line is marked valid and dirty. The line is marked not valid.
Test and clean DCache
Tests a number of cache lines, and cleans one of them if
any are dirty. Returns the overall dirty state of the cache in
bit 30. (See “Test and clean DCache instructions” on
page 96).
Test, clean, and invalidate DCache
Tests a number of cache lines, and cleans one of them if
any are dirty. When the entire cache has been tested and
cleaned, it is invalidated. (See “Test and clean DCache
instructions” on page 96).
Prefetch ICache line
Performs an ICache lookup of the specified modified
virtual address. If the cache misses and the region is
cachable, a linefill is performed.
Summary of Contents for NS9215
Page 1: ...NS9215 Hardware Reference 90000847_C Release date 10 April 2008...
Page 3: ......
Page 4: ......
Page 26: ...26 Hardware Reference NS9215...
Page 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Page 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Page 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
Page 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
Page 202: ...S Y S T E M C O N T RO L M OD U L E RTC Module Control register 202 Hardware Reference NS9215...
Page 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Page 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Page 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Page 515: ...PA CKA GING Processor Dimensions www digiembedded com 515...
Page 516: ...PA CKA GING Processor Dimensions 516 Hardware Reference NS9215...