Juno: Support entry into a standby state
This patch adds support on the Juno platform for entering a wfi in
response to a PSCI CPU_SUSPEND call where the state type is a
standby state.
Change-Id: I0a102dee1f8d2ad936c63ad1d1d3ad001a4a4768
diff --git a/plat/juno/plat_pm.c b/plat/juno/plat_pm.c
index 74ce89f..a3f6bdd 100644
--- a/plat/juno/plat_pm.c
+++ b/plat/juno/plat_pm.c
@@ -275,12 +275,47 @@
}
/*******************************************************************************
+ * Handler called when an affinity instance is about to enter standby.
+ ******************************************************************************/
+int32_t juno_affinst_standby(unsigned int power_state)
+{
+ unsigned int target_afflvl;
+ unsigned int scr;
+
+ /* Sanity check the requested state */
+ target_afflvl = psci_get_pstate_afflvl(power_state);
+
+ /*
+ * It's possible to enter standby only on affinity level 0 i.e. a cpu
+ * on the Juno. Ignore any other affinity level.
+ */
+ if (target_afflvl != MPIDR_AFFLVL0)
+ return PSCI_E_INVALID_PARAMS;
+
+ scr = read_scr_el3();
+ /* Enable PhysicalIRQ bit for NS world to wake the CPU */
+ write_scr_el3(scr | SCR_IRQ_BIT);
+ isb();
+ dsb();
+ wfi();
+
+ /*
+ * Restore SCR to the original value, synchronisation of scr_el3 is
+ * done by eret while el3_exit to save some execution cycles.
+ */
+ write_scr_el3(scr);
+
+ return PSCI_E_SUCCESS;
+}
+
+/*******************************************************************************
* Export the platform handlers to enable psci to invoke them
******************************************************************************/
static const plat_pm_ops_t juno_ops = {
.affinst_on = juno_affinst_on,
.affinst_on_finish = juno_affinst_on_finish,
.affinst_off = juno_affinst_off,
+ .affinst_standby = juno_affinst_standby,
.affinst_suspend = juno_affinst_suspend,
.affinst_suspend_finish = juno_affinst_suspend_finish,
.system_off = juno_system_off,