TMPR4937 datasheet(272/552 Pages) TOSHIBA

272 / 552 page

Chapter 10 PCI Controller

10-14

PCI Reset is detected by either using the PCI Bus Reset Signal as the TX4937 overall reset signal or

using the PCI Bus Reset Signal assertion detection device that the system provides. Then, the software

reset the PCI Controller. The software uses a hardware reset (PCICCFG.HRST) of the PCI Controller

Configuration Register to reset the PCI Controller.

10.3.9 Power Management

The TX4937 PCI Controller supports power management functions that are compliant to PCI Bus

Power Management Interface Specifications Version 1.1.

The PCI Host device controls the system status by reporting the power management state to the PCI

Satellite device. Also, the PCI Satellite device uses the PME* signal to report requests for changing the

power management state or to report to the PCI Host device that a power management event has

occurred.

10.3.9.1 Power Management State

In the case of the PCI Bus Power Management Interface Specifications, four power

management states are defined from State D0 to State D3. The TX4937 supports states D0 through

D3. Figure 10.3.7 illustrates the power management state transition.

After Power On Reset, or when transitioning from the D3HOT state to the D0 state, the power

management state becomes uninitialized D0. If initialized by the system software at this point, the

state transitions to D0 Active.

If an external PCI Host device writes 11b (D3HOT) to the PowerState field of the Power

Management Control Status Register (PMCSR) of the Configuration space when in the Satellite

mode, then the Power Management State Change bit (P2GSTATUS.PMSC) of the P2G Status

Change interrupts. The PowerState field value can be read from the PowerState field

(PCISSTATUS.PS) of the Satellite Mode PCI Status Register.

The TX4937 uses the software to change the system status after a status change is detected.

Figure 10.3.7 Transition of the Power Management States

Uninitialized

D0 Active

D3hot

D3cold

PCI RST**

(RESET**)

VCCCut-off

Software Reset

Power On Reset

(RESET**)

Initialization by the

System Software

Change PMCSR

PowerState

TMPR4937 Datasheet(PDF) 272 Page - Toshiba Semiconductor