MSC8144E Reference Manual, Rev. 3
26-18
Freescale
Semiconductor
Security Engine (SEC)
26.2.4 Controller Interrupts
All interrupt outputs from other blocks in the SEC feed to the controller as interrupt conditions.
In addition, the controller can detect some interrupt independently. The controller maintains an
Interrupt Status Register (ISR) with bits corresponding to all of possible interrupt conditions. If
an interrupt condition occurs and it is enabled by corresponding bit of the Interrupt Enable
Register (IER), then the associated ISR bit is set, indicating the presence of a pending interrupt.
Whenever bits are set in the ISR, the controller asserts its interrupt output line to the core
processor. In addition to the main interrupt (that includes all the interrupt conditions), there are
five additional interrupts, one for each channel to indicate a DONE state and a general interrupt.
To handle an interrupt, the core processor must read the ISR to determine the interrupt source. It
may need to perform further reads of Interrupt Status Registers in other blocks to obtain more
detailed information about the cause. In some cases, the core processor may need to take action to
clear the root cause of the interrupt. After that, the core processor can clear the desired bit of the
ISR by writing a 1 to the corresponding bit of the Interrupt Clear Register (ICR). If the cause of
the interrupt condition is not cleared, or if there is another interrupt condition from the same
source, then the Interrupt Status Register bit clears for a cycle and then sets again, keeping the
interrupt output line to the core processor active. If the ISR bit is successfully cleared and no
other interrupt conditions are present, the controller deasserts its interrupt output. If any interrupts
are still pending in the ISR, the interrupt output remains asserted.
The EU interrupt conditions can be blocked at two different levels. There is an Interrupt Mask
Register in each EU that can block particular interrupt conditions before they reach the EU ISR.
In addition, interrupt conditions from EUs can be individually blocked by bits of the controller
IER before they reach the controller ISR. For normal operation, interrupt conditions from EUs
are disabled in the controller IER, but they still reach the channel, and the channel produces Done
or Error interrupts to the core processor as needed. Interrupt conditions from the channels and
controller can only be blocked through the controller IER.
A channel can generate frequent interrupts, especially if it is configured to interrupt at the
completion of each descriptor. To make sure that the core processor receives the right number of
interrupts, each channel Done interrupt has a special queuing feature. If multiple Channel Done
interrupts are generated before the first is cleared, then the additional interrupts are queued by the
controller. When the core processor clears a channel interrupt, if there are no other interrupts
queued from that channel, then the channel Done interrupt is deasserted. If other interrupts
remain in the queue, the controller deasserts the interrupt for one cycle and then reasserts it again.
Interrupts are queued separately for each channel.
The SEC generates a single interrupt to the device embedded programmable interrupt controller
(EPIC). See the MSC8144 SC3400 DSP Core Subsystem Reference Manual for additional
information on the EPIC. The user allows SEC interrupts to be reported to the core processor by
clearing the mask bit in the associated vector/priority register of the EPIC.
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...