AMD Geode SC1201 User Manual
Page 275
AMD Geode™ SC1200/SC1201 Processor Data Book
275
Core Logic Module - Audio Registers - Function 3
32579B
Offset 40h
Audio Bus Master 4 Command Register (R/W)
Reset Value: 00h
Audio Bus Master 4: Output to codec; 16-Bit; Slot 6 or 11 (F3BAR0+Memory Offset 08h[19] selects slot).
7:4
Reserved. Must be set to 0. Must return 0 on reads.
3
Read or Write Control. Set the transfer direction of Audio Bus Master 4.
0: PCI reads are performed.
1: PCI writes are performed.
This bit must be set to 0 (read) and should not be changed when the bus master is active.
2:1
Reserved. Must be set to 0. Must return 0 on reads.
0
Bus Master Control. Controls the state of the Audio Bus Master 4.
0: Disable.
1: Enable.
Setting this bit to 1 enables the bus master to begin data transfers. When writing 0 to this bit, the bus master must be either
paused or have reached EOT. Writing 0 to this bit while the bus master is operating, results in unpredictable behavior (and
may crash the bus master state machine). The only recovery from this condition is a PCI reset.
Offset 41h
Audio Bus Master 4 SMI Status Register (RC)
Reset Value: 00h
Audio Bus Master 4: Output to codec; 16-Bit; Slot 6 or 11 (F3BAR0+Memory Offset 08h[19] selects slot).
7:2
Reserved.
1
Bus Master Error. Indicates if hardware encountered a second EOP before software cleared the first.
0: No.
1: Yes.
If hardware encounters a second EOP (end of page) before software cleared the first, it causes the bus master to pause
until this register is read to clear the error.
0
End of Page. Bus master transferred data which is marked by the EOP bit in the PRD table (bit 30).
0: No.
1: Yes.
Offset 42h-43h
Not Used
Offset 44h-47h
Audio Bus Master 4 PRD Table Address (R/W)
Reset Value: 00000000h
Audio Bus Master 4: Output to codec; 16-Bit; Slot 6 or 11 (F3BAR0+Memory Offset 08h[19] selects slot).
31:2
Pointer to the Physical Region Descriptor Table. This register is a PRD table pointer for Audio Bus Master 4.
When written, this register points to the first entry in a PRD table. Once Audio Bus Master 4 is enabled (Command Register
bit 0 = 1), it loads the pointer and updates this register (by adding 08h) so that it points to the next PRD.
When read, this register points to the next PRD.
1:0
Reserved. Must be set to 0.
Note:
The Physical Region Descriptor (PRD) table consists of one or more entries - each describing a memory region to or from
which data is to be transferred. Each entry consists of two DWORDs.
DWORD 0:
[31:0]
= Memory Region Physical Base Address
DWORD 1:
31
= End of Table Flag
30
= End of Page Flag
29
= Loop Flag (JMP)
[28:16]
= Reserved (0)
[15:0]
= Byte Count of the Region (Size)
Table 6-38. F3BAR0+Memory Offset: Audio Configuration Registers (Continued)
Bit
Description