2.5.5 SPI Collator clock Q-Channel

The SPI Collator has a clock Q-Channel interface that accepts requests from an external clock gating source, such as the system clock controller.

When signal qactive_clk_col is LOW, it indicates that all SPI toggles and level transitions have been passed to the Distributor, and that the SPI Collator does not require the clock.

If qactive_clk_col is HIGH, the SPI Collator rejects any attempt to enter a low-power mode.

If qreqn_clk_col is LOW and is accepted, the SPI Collator enters low-power mode and no new messages are sent to the Distributor until it enters low-power mode. If any interrupt line changes state, qactive_clk_col is asserted.

Note:

In low-power mode, it is only safe to stop the Collator clock if all edge-triggered interrupts into the SPI Collator are pulse extended to ensure that edges are not missed.
Non-ConfidentialPDF file icon PDF version100336_0104_00_en
Copyright © 2016–2018 Arm Limited or its affiliates. All rights reserved.