[PATCH v8 23/26] drivers: firmware: psci: Try to attach CPU devices to their PM domains

[Ulf Hansson <ulf.hansson@linaro.org>]

In case the OS initiated CPU suspend mode have been enabled, the PM domain
topology for CPUs have earlier been created by PSCI. Let's use this
information in psci_dt_cpu_init_idle() as a condition for when it makes
sense to try to attach the CPU to its corresponding PM domain, via calling
of_genpd_attach_cpu().

If the CPU is attached successfully to its PM domain, idle management is
now fully prepared to be controlled through runtime PM for the CPU.

Cc: Lina Iyer <ilina@codeaurora.org>
Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/firmware/psci/psci.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 80c286d83369..700e0e995871 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -20,6 +20,7 @@
 #include <linux/linkage.h>
 #include <linux/of.h>
 #include <linux/pm.h>
+#include <linux/pm_domain.h>
 #include <linux/printk.h>
 #include <linux/psci.h>
 #include <linux/reboot.h>
@@ -91,6 +92,7 @@ static u32 psci_function_id[PSCI_FN_MAX];
 
 static DEFINE_PER_CPU(u32, domain_state);
 static u32 psci_cpu_suspend_feature;
+static bool psci_osi_mode_enabled;
 
 u32 psci_get_domain_state(void)
 {
@@ -339,6 +341,14 @@ static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
 
 	/* Idle states parsed correctly, initialize per-cpu pointer */
 	per_cpu(psci_power_state, cpu) = psci_states;
+
+	/* If running OSI mode, attach the CPU device to its PM domain. */
+	if (psci_osi_mode_enabled) {
+		ret = of_genpd_attach_cpu(cpu);
+		if (ret)
+			goto free_mem;
+	}
+
 	return 0;
 
 free_mem:
@@ -753,6 +763,7 @@ int __init psci_dt_topology_init(void)
 		goto out;
 	}
 
+	psci_osi_mode_enabled = true;
 	pr_info("OSI mode enabled.\n");
 out:
 	of_node_put(np);
-- 
2.17.1