Freescale Semiconductor POWERPC MPC860T - Manual (Page 32)

5-2 MPC860T (Rev. D) Fast Ethernet Controller Supplement MOTOROLA
PRELIMINARYÑSUBJECT TO CHANGE WITHOUT NOTICE
5.2.1 SDMA ConÞguration Register (SDCR)
The SDMA conÞguration register (SDCR), shown in Figure 5-2, is used to conÞgure all 16
SDMA channels. It is always read/write in supervisor mode, although writing to the SDCR
is not recommended unless the CPM is disabled. SDCR interacts with the DMA controllers
in the FEC. Refer to the MPC860 PowerQUICC UserÕs Manual for more information.
Table 5-1 describes SDCR Þelds.
Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Field Ñ
Reset 0000_0000_0000_0000
R/W R/W
Address (IMMR & 0xFFFF0000) + 0x030
Bit 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Field Ñ FRZ Ñ FAID RAID
Reset 0 0 00_0000_0000 00 00
R/W R R/W R R/W R/W
Address (IMMR & 0xFFFF0000) + 0x030
Figure 5-2. SDMA Configuration Register (SDCR)
Table 5-1. SDCR Field Descriptions
Bits Name Description
0Р16 С Reserved. These bits are reserved and should be cleared.
17 FRZ Freeze. Determines the action to be taken when the FRZ signal is asserted. The SDMA negates
BR and keeps it that way until the FRZ signal is negated or reset occurs.
0
The SDMA channels ignore the FRZ signal.
1 The SDMA channels freeze on the next bus cycle.
19Р27 С Reserved, should be cleared for typical applications.
28Ð29 FAID FEC arbitration ID. Determines FEC arbitration priority for the U bus; 00 for typical applications.
00 Priority 6 (highest)
01 Priority 5
10 Priority 2
11 Priority 1 (lowest)
30Ð31 RAID RISC controller arbitration ID. Determines the SDMA channel arbitration ID, which establishes the
priority level of bus arbitration among modules that can become master of the U bus (01 for
typical applications). The instruction cache, data cache, SIU, and SDMAs compete for bus
mastership. Arbitration IDs for all other bus masters are internally Þxed.
00 Priority 6 (highest)
01 Priority 5
10 Priority 2
11 Priority 1 (lowest)
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