ARM ARM1176JZF-S User Manual

System Control Coprocessor
ARM DDI 0301H Copyright © 2004-2009 ARM Limited. All rights reserved. 3-85
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Table 3-80 lists the results of attempted access for each mode.
To use the Data Memory Barrier operation write CP15 with <Rd> SBZ and:
• Opcode_1 set to 0
• CRn set to c7
• CRm set to c10
• Opcode_2 set to 5.
For example:
MCR p15,0,<Rd>,c7,c10,5 ; Data Memory Barrier Operation.
For more details, see Explicit Memory Barriers on page 6-25.
Wait For Interrupt operation
The purpose of the Wait For Interrupt operation is to put the processor in to a low power state,
see Standby mode on page 10-3.
The Wait For Interrupt operation is:
•in CP15 c7
• 32-bit write only access, common to Secure and Non-secure worlds
• accessible in privileged modes only.
Table 3-81 lists the results of attempted access for each mode.
To use the Wait For Interrupt operation write CP15 with <Rd> SBZ and:
• Opcode_1 set to 0
• CRn set to c7
• CRm set to c0
• Opcode_2 set to 4.
For example:
MCR p15,0,<Rd>,c7,c0,4 ; Wait For Interrupt.
This puts the processor into a low-power state and stops it executing following instructions until
an interrupt, an imprecise external abort, or a debug request occurs, regardless of whether the
interrupts or external imprecise aborts are disabled by the masks in the CPSR. When an interrupt
does occur, the MCR instruction completes. If interrupts are enabled, the IRQ or FIQ handler is
entered as normal. The return link in R14_irq or R14_fiq contains the address of the MCR
instruction plus 8, so that the normal instruction used for interrupt return (
SUBS PC,R14,#4 )
returns to the instruction following the MCR.
Table 3-80 Results of access to the Data Memory Barrier operation
Read Write
Undefined exception Data
Table 3-81 Results of access to the Wait For Interrupt operation
Secure Privileged Non-secure Privileged
User
Read Write Read Write
Undefined exception Wait For Interrupt Undefined exception Wait For Interrupt Undefined exception

ARM ARM1176JZF-S Specifications

General

Brand	ARM
Model	ARM1176JZF-S
Category	Computer Hardware
Language	English