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After an abort occurs, the action of the DMAC depends on the thread type:
• DMA channel thread—The thread immediately moves to the Faulting completing state. In this state, the
DMAC performs the following operations:
• Sets the
irq_abort
signal high.
• Stops executing instructions for the DMA channel.
• Invalidates all cache entries for the DMA channel updates the
CPC n
register to contain the address
of the aborted instruction provided that the abort is precise.
• Does not generate AXI accesses for any instructions remaining in the read queue and write queue.
• Permits currently active AXI transactions to complete.
After the transactions for the DMA channel finish, the thread moves to the Faulting state.
Note:
• DMA manager thread—The thread immediately moves to the Faulting state and the DMAC sets the
irq_abort
signal high.
The external agent can respond to the assertion of the
irq_abort
signal by all of the following:
• Reading the status of the
FSRD
register to determine if the DMA manager is Faulting. In the Faulting
state, the
FSRD
register provides the cause of the abort.
• Reading the status of the
FSRC
register to determine if a DMA channel is Faulting. In the Faulting
state, the
FSRC
register provides the cause of the abort.
To enable a thread in the Faulting state to move to the Stopped state, the external agent must:
• Program the
DBGINST0
register with the encoding for the
DMAKILL
instruction.
• Write to the
DBGCMD
register.
If the aborted thread is secure, you must use the secure slave interface to update these registers.
Note:
After a thread in the Faulting state executes
DMAKILL
, it moves to the Stopped state.
Security Usage
When the DMAC exits from reset, the status of the configuration signals configures the security for:
• DMA manager thread—The
DNS
bit in the DSR register returns the security state of the DMA manager
thread.
• Events and interrupts—The
INS
bit in the
CR3
register returns the security state of the event-interrupt
resources.
• Peripheral request interfaces—The
PNS
bit in the
CR4
register returns the security state of these interfaces.
Additionally, each DMA channel thread contains a dynamic non-secure bit,
CNS
, that is valid when the
channel is not in the Stopped state.
DMA Controller
Altera Corporation
cv_54016
Security Usage
16-18
2013.12.30