Texas Instruments TMS320DM646x Mdio Module Interrupt Events and Requests, Link Change Interrupt

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Architecture

2.16.2MDIO Module Interrupt Events and Requests

The MDIO module generates two interrupt events:

∙LINKINT: Serial interface link change interrupt. Indicates a change in the state of the PHY link

∙USERINT: Serial interface user command event complete interrupt

2.16.2.1Link Change Interrupt

The MDIO module asserts a link change interrupt (LINKINT) if there is a change in the link state of the PHY corresponding to the address in the PHYADRMON bit in the MDIO user PHY select register n (USERPHYSELn), and if the LINKINTENB bit is also set in USERPHYSELn. This interrupt event is also captured in the LINKINTRAW bit in the MDIO link status change interrupt register (LINKINTRAW). LINKINTRAW bits 0 and 1 correspond to USERPHYSEL0 and USERPHYSEL1, respectively.

When the interrupt is enabled and generated, the corresponding LINKINTMASKED bit is also set in the MDIO link status change interrupt register (LINKINTMASKED). The interrupt is cleared by writing back the same bit to LINKINTMASKED (write to clear).

2.16.2.2User Access Completion Interrupt

When the GO bit in one of the MDIO user access registers (USERACCESSn) transitions from 1 to 0 (indicating completion of a user access) and the corresponding USERINTMASKSET bit in the MDIO user command complete interrupt mask set register (USERINTMASKSET) corresponding to USERACCESS0 or USERACCESS1 is set, a user access completion interrupt (USERINT) is asserted. This interrupt event is also captured in the USERINTRAW bit in the MDIO user command complete interrupt register (USERINTRAW). USERINTRAW bits 0 and bit 1 correspond to USERACCESS0 and USERACCESS1, respectively.

When the interrupt is enabled and generated, the corresponding USERINTMASKED bit is also set in the MDIO user command complete interrupt register (USERINTMASKED). The interrupt is cleared by writing back the same bit to USERINTMASKED (write to clear).

2.16.3Proper Interrupt Processing

All the interrupts signaled from the EMAC and MDIO modules are level driven, so if they remain active, their level remains constant; the CPU core requires edge-triggered interrupts. In order to properly convert the level-driven interrupt signal to an edge-triggered signal, the application software must make use of the interrupt control logic contained in the EMAC control module.

Section 2.6.3 discusses the interrupt control contained in the EMAC control module. For safe interrupt processing, upon entry to the ISR, the software application should disable interrupts using the EMAC control module interrupt control registers (CMRXTHRESHINTEN, CMRXINTEN, CMTXINTEN, and CMMISCINTEN), and then reenable them upon leaving the ISR. If any interrupt signals are active at that time, this creates another rising edge on the interrupt signal going to the CPU interrupt controller, thus triggering another interrupt. The EMAC control module also implements the optional interrupt pacing.

2.16.4Interrupt Multiplexing

The EMAC control module combines all the different interrupt signals from both the EMAC and MDIO modules and generates four separate interrupt signals (Table 5) that are wired to the ARM interrupt controller (AINTC), as seen in Figure 12. Once this interrupt is generated, the reason for the interrupt can be read from the MAC input vector register (MACINVECTOR) located in the EMAC memory map. MACINVECTOR combines the status of the following 28 interrupt signals: TXPENDn, RXPENDn, RXTHRESHPENDn, STATPEND, HOSTPEND, LINKINT, and USERINT.

For more details on the ARM interrupt controller (AINTC), see the TMS320DM646x DMSoC ARM Subsystem Reference Guide (SPRUEP9).

SPRUEQ6–December 2007 Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO) 59

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