
SD Host Controller Programming Model
222
September 2005
SCPS110
12.13 Interrupt Pin Register
This register decodes the interrupt select inputs and returns the proper interrupt value based on Table 128,
indicating that the SD host controller uses an interrupt. If one of the USE_INTx terminals is asserted, the
interrupt select bits are ignored, and this register returns the interrupt value for the highest priority USE_INTx
terminal that is asserted. If bit 28, the tie-all bit (TIEALL), in the system control register (PCI offset 80h, see
Section 4.29) is set to 1b, then the controller asserts the USE_INTA input to the SD host controller core. If bit
28 (TIEALL) in the system control register (PCI offset 80h, see Section 4.29) is set to 0b, then none of the
USE_INTx inputs are asserted and the interrupt for the SD host controller function is selected by the INT_SEL
bits in the SD host general control register.
Function 3 register offset: 3Dh
Register type:
Read-only
Default value:
0Xh
BIT NUMBER
7
6
5
4
3
2
1
0
RESET STATE
0
X
Table 128. PCI Interrupt Pin Register
INT_SEL BITS
USE_INTA
INTPIN
00
0
01h (INTA)
01
0
02h (INTB)
10
0
03h (INTC)
11
0
04h (INTD)
XX
1
01h (INTA)
12.14 Minimum Grant Register
The minimum grant register contains the minimum grant value for the SD host controller core.
Function 3 register offset: 3Eh
Register type:
Read/Update
Default value:
07h
BIT NUMBER
7
6
5
4
3
2
1
0
RESET STATE
0
1
Table 129. Minimum Grant Register Description
BIT
FIELD NAME
TYPE
DESCRIPTION
70
MIN_GNT
RU
Minimum grant. The contents of this field may be used by host BIOS to assign a latency timer register value
to the SD host controller. The default for this register indicates that the SD host controller may need to
sustain burst transfers for nearly 64
s and thus request a large value be programmed in bits 158 of the
latency timer and class cache line size register at offset 0Ch in the PCI configuration space (see
Section 12.6).