ATM Exceptions
MPC885 PowerQUICC Family Reference Manual, Rev. 2
41-2
Freescale Semiconductor
GINT, the host processes each valid queue entry in turn, clearing each V bit and all flagged event bits so
that the entry can be reused by the CP. The host continues servicing entries until it reaches an invalid entry
(whose V bit is already cleared).
41.1
ATM Event Registers
The ATM event registers generate interrupts to the host and report on events that are common to all
channels of a controller. The global interrupt (GINT) bit indicates that at least one channel-specific
interrupt has been added to the interrupt queue. In UTOPIA mode, the IDSR1 register is used as an
exception event register; in serial ATM mode the SCC event registers (SCCE) are used for events.
41.1.1
UTOPIA Event Register (IDSR1)
The IDSR1 register is the ATM event register when operating in UTOPIA mode. IDSR1 is used to report
events and generate interrupt requests for the UTOPIA interface. Note that in UTOPIA mode, interrupts
from the ATM port are reported with an IDMA1 vector in the CIVR, and the IDMA1 bit is set in the CIPR.
Setting the corresponding bit in the mask register IDMR1 enables the actual generation of the interrupt
request. Event bits are cleared by writing ones; writing zeros has no effect. The UTOPIA event and mask
registers are shown in
Figure 41-2
.
Table 41-1
describes the UTOPIA event register fields.
0
1
2
3
4
5
6
7
Field
—
UTERR
SYNC
IQOV
GINT
GUN
GOV
Figure 41-2. UTOPIA Event Register (IDSR1) and Mask Register (IDMR1)
Table 41-1. UTOPIA Event Register (IDSR1) Field Descriptions
Bits
Name
Description
0–1
—
Reserved
2
UTER
R
UTOPIA error. When set, indicates that a serious UTOPIA receiver protocol state machine error has
occurred. Note that during the initialization phase of the UTOPIA interface, this indication could be
set if the setup is not synchronized well to activity on the UTOPIA. If it occurs while the system is
active it signifies a serious UTOPIA protocol error on the receiver side like a missing or misplaced
SOC signal or receiver FIFO overruns due to lack of microcode service.
3
SYNC
Cell synchronization lost. When set, indicates that the UTOPIA receiver has lost the start of cell
(SOC) indication. When this occurs the receiver stops receiving cells until it regains SOC
synchronization. SRSTATE[SNC] indicates that the receiver is waiting for resynchronization.
Note:
The SYNC interrupt can be issued multiple times during the synchronization process until full
synchronization is achieved.
4
IQOV
Interrupt queue overflow. Set by the CP whenever an overflow condition in the interrupt queue
occurs. This condition occurs if the CP attempts to write a new interrupt entry into a valid entry (V =
1) not yet handled by the host.
5
GINT
Global interrupt. Indicates that at least one new entry has been added to the interrupt queue. After
clearing the GINT event flag, the host begins processing the entries using the service pointer. The
host returns from the interrupt handler when it reaches an invalid queue entry (V = 0).
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