AMD Geode SC2200, Data Book, Page: 270 / 429

282 AMD Geode™ SC2200 Processor Data Book
Core Logic Module - Audio Registers - Function 3 32580B
Offset 28h Audio Bus Master 1 Command Register (R/W) Reset Value: 00h
Audio Bus Master 1: Input from codec; 32-Bit; Left and Right Channels; Slots 3 and 4.
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 1.
0: PCI reads are performed.
1: PCI writes are performed.
This bit must be set to 1 (write) 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 1.
0: Disable.
1: Enable.
Setting this bit to 1 enables the bus master to begin data transfers. When writing this bit to 0, the bus master must be either
paused or reached EOT. Writing this bit to 0 while the bus master is operating results in unpredictable behavior (and may
cause a crash of the bus master state machine). The only recovery from this condition is a PCI reset.
Offset 29h Audio Bus Master 1 SMI Status Register (RC) Reset Value: 00h
Audio Bus Master 1: Input from codec; 32-Bit; Left and Right Channels; Slots 3 and 4.
7:2 Reserved.
1 Bus Master Error. Indicates if hardware encountered a second EOP before software has cleared the first.
0: No.
1: Yes.
If hardware encounters a second EOP (end of page) before software has cleared the first, it causes the bus master to pause
until this register is read to clear the error.
0 End of Page. Indicates if the bus master transferred data which is marked by EOP bit in the PRD table (bit 30).
0: No.
1: Yes.
Offset 2Ah-2Bh Not Used
Offset 2Ch-2Fh Audio Bus Master 1 PRD Table Address (R/W) Reset Value: 00000000h
Audio Bus Master 1: Input from codec; 32-Bit; Left and Right Channels; Slots 3 and 4.
31:2 Pointer to the Physical Region Descriptor Table. This bit field is a PRD table pointer for Audio Bus Master 1.
When written, this register points to the first entry in a PRD table. Once Audio Bus Master 1 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. Memory Offset: Audio Configuration Registers (Continued)
Bit Description