Freescale Semiconductor MPC8260 - Manual (Page 390)

PCI Bridge
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
9-84 Freescale Semiconductor
9.12.3.4.8 Queue Base Address Register (QBAR)
This register specifies the beginning of the circular queue structure in local memory. The following QBAR
should be accessed only from the 60x bus and only in agent mode. Accesses while in host mode or from
the PCI bus have undefined results.
Figure 9-80. Queue Base Address Register (QBAR)
Table 9-65 describes QBAR fields.
5–1 CQS RW Circular queue size. CQS refers to each individual queue, not the total size of all four
queues together.
00001 4K entries (16 Kbytes)
00010 8K entries (32 Kbytes)
00100 16K entries (64 Kbytes)
01000 32K entries (128 Kbytes)
10000 64K entries (256 Kbytes)
All others reserved.
0 CQE RW Circular queue enable. When set will allow PCI masters to access the inbound and
outbound queue ports. Writes are ignored and reads will return 0xFFFF_FFFF when
this bit is cleared. Normally, this bit is set only if software has initialized all pointers and
configuration registers.
31 20 19 16
Field QBA —
Reset 0000_0000_0000_0000
R/W R/W
Addr 0x104F2
15 0
Field —
Reset 0000_0000_0000_0000
R/W R/W
Addr 0x104F0
Table 9-65. QBAR Field Descriptions
Bits Name Access Description
31–20 QBA RW Queue base address. Base address of circular queue in local memory. It must be
aligned to a 1Mbyte boundary.
19–0 — R Reserved, should be cleared.
Table 9-64. MUCR Field Descriptions
Bits Name Access Description