int irq_reenable = clockevent_state_periodic(evt);
/*
- * Any write to CTRL reg ACks the interrupt, we rewrite the
- * Count when [N]ot [H]alted bit.
- * And re-arm it if perioid by [I]nterrupt [E]nable bit
+ * 1. ACK the interrupt
+ * - For ARC700, any write to CTRL reg ACKs it, so just rewrite
+ * Count when [N]ot [H]alted bit.
+ * - For HS3x, it is a bit subtle. On taken count-down interrupt,
+ * IP bit [3] is set, which needs to be cleared for ACK'ing.
+ * The write below can only update the other two bits, hence
+ * explicitly clears IP bit
+ * 2. Re-arm interrupt if periodic by writing to IE bit [0]
*/
write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);