vi
EPC User
’
s Manual Revision 1.05
Copyright 1997-2000, V3 Semiconductor Inc.
9.1.2
9.1.3
9.1.4
9.1.5
Controlling Target IDSEL Lines.................................................................................... 83
Generating Configuration Reads and Writes................................................................ 84
Using Configuration Information................................................................................... 84
Determining the Presence of Target Devices During Configuration............................. 85
9.2
Configuration as a Target Bridge............................................................................................... 85
9.2.1
EPC Base Register Response to Configuration Inquiries ............................................ 85
9.2.2
EPC Expansion ROM Base Register Response to Configuration Inquiries ................. 87
Chapter 10 PC Compatibility
89
10.1 Real Mode DOS Compatibility Aperture.................................................................................... 89
10.2 Example: VGA Peripheral.......................................................................................................... 91
Chapter 11 Mailbox Registers
93
11.1 Overview.................................................................................................................................... 93
11.1.1 Accessing the Mailbox Registers.................................................................................. 93
11.1.2 Doorbell Interrupts........................................................................................................ 94
11.2 Programming the Mailbox Registers ......................................................................................... 95
11.2.1 Enabling Doorbell Interrupt Requests........................................................................... 95
11.2.2 Clearing Doorbell Interrupt Requests ........................................................................... 95
Chapter 12 Interrupt Control
97
12.1 Local Interrupt Control Unit........................................................................................................ 97
12.1.1 Overview....................................................................................................................... 97
12.1.2 Local Interrupt Requests .............................................................................................. 98
12.1.3 Masking Local Interrupt Requests................................................................................ 98
12.1.4 Local Interrupt Event Signal ......................................................................................... 98
12.2 PCI Interrupt Control Unit (PICU).............................................................................................. 99
12.2.1 Overview....................................................................................................................... 99
12.2.2 PCI Interrupt Pins (INTA through INTD)..................................................................... 100
12.2.2.1 Configuring a PCI Interrupt Pin as an Interrupt Request Output................ 100
12.2.2.2 Configuring a PCI Interrupt Pin as an Interrupt Request Input................... 100
12.2.2.3 Crosspoint Interrupt Routing Mechanism................................................... 100
12.2.3 Internal PCI Interrupt Requests.................................................................................. 101
12.2.3.1 Mailbox and DMA PCI Interrupt Requests ................................................. 101
12.2.3.2 Local Direct Interrupt Request.................................................................... 102
12.2.3.3 Routing the Internal PCI Interrupt Requests to an INTx Pin....................... 102
12.2.4 PICU Configuration Example...................................................................................... 102
12.3 Generating PCI Interrupt Acknowledge Cycles....................................................................... 103