cpuidle: PSCI: Improve support for suspend-to-RAM for PSCI OSI mode

[ Upstream commit 171b66e2e2e9d80b93c8cff799e6175074b22297 ]

When PSCI OSI mode is supported the syscore flag is set for the CPU devices
that becomes attached to their PM domains (genpds). In the suspend-to-idle
case, we call dev_pm_genpd_suspend|resume() to allow genpd to properly
manage the power-off/on operations (pick an idlestate and manage the on/off
notifications).

For suspend-to-ram, dev_pm_genpd_suspend|resume() is currently not being
called, which causes a problem that the genpd on/off notifiers do not get
sent as expected. This prevents the platform-specific operations from being
executed, typically needed just before/after the boot CPU is being turned
off/on.

To deal with this problem, let's register a syscore ops for cpuidle-psci
when PSCI OSI mode is being used and call dev_pm_genpd_suspend|resume()
from them. In this way, genpd regains control of the PM domain topology and
then sends the on/off notifications when it's appropriate.

Reported-by: Maulik Shah <quic_mkshah@quicinc.com>
Suggested-by: Maulik Shah <quic_mkshah@quicinc.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Maulik Shah <quic_mkshah@quicinc.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index b51b5df..540105c 100644 (file)
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -23,6 +23,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/cpuidle.h>
 
@@ -131,6 +132,49 @@ static int psci_idle_cpuhp_down(unsigned int cpu)
        return 0;
 }
 
+static void psci_idle_syscore_switch(bool suspend)
+{
+       bool cleared = false;
+       struct device *dev;
+       int cpu;
+
+       for_each_possible_cpu(cpu) {
+               dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;
+
+               if (dev && suspend) {
+                       dev_pm_genpd_suspend(dev);
+               } else if (dev) {
+                       dev_pm_genpd_resume(dev);
+
+                       /* Account for userspace having offlined a CPU. */
+                       if (pm_runtime_status_suspended(dev))
+                               pm_runtime_set_active(dev);
+
+                       /* Clear domain state to re-start fresh. */
+                       if (!cleared) {
+                               psci_set_domain_state(0);
+                               cleared = true;
+                       }
+               }
+       }
+}
+
+static int psci_idle_syscore_suspend(void)
+{
+       psci_idle_syscore_switch(true);
+       return 0;
+}
+
+static void psci_idle_syscore_resume(void)
+{
+       psci_idle_syscore_switch(false);
+}
+
+static struct syscore_ops psci_idle_syscore_ops = {
+       .suspend = psci_idle_syscore_suspend,
+       .resume = psci_idle_syscore_resume,
+};
+
 static void psci_idle_init_cpuhp(void)
 {
        int err;
@@ -138,6 +182,8 @@ static void psci_idle_init_cpuhp(void)
        if (!psci_cpuidle_use_cpuhp)
                return;
 
+       register_syscore_ops(&psci_idle_syscore_ops);
+
        err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
                                        "cpuidle/psci:online",
                                        psci_idle_cpuhp_up,