[RFC PATCH 1/1] soc: qcom: rpmh-rsc: Register s2idle_ops to indicate s2ram behavior in s2idle

[Manivannan Sadhasivam]

RPMh in some Qcom SoCs like Makena (SC8280XP) implement deeper low power
state similar to that of Suspend to RAM (S2RAM) despite PSCI firmware only
supporting s2idle. So the OS never knows the platform will be transitioning
to deeper low power state and the device drivers do not prepare for the
possible power loss during system suspend.

So register the s2idle_ops for this platform and invoke
pm_set_{suspend/resume}_via_firmware() APIs in the callbacks to let the
drivers know that the firmware is going to get involved in the suspend
process and they need to be prepared for that by taking actions such as
shutting down or resetting the devices.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>
---
 drivers/soc/qcom/rpmh-rsc.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index c6f7d5c9c493..a7a03b50c289 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -25,6 +25,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/suspend.h>
 #include <linux/wait.h>
 
 #include <clocksource/arm_arch_timer.h>
@@ -1028,6 +1029,25 @@ static int rpmh_probe_tcs_config(struct platform_device *pdev, struct rsc_drv *d
 	return 0;
 }
 
+static int rpmh_rsc_s2idle_begin(void)
+{
+	pm_set_suspend_via_firmware();
+
+	return 0;
+}
+
+static int rpmh_rsc_s2idle_prepare_late(void)
+{
+	pm_set_resume_via_firmware();
+
+	return 0;
+}
+
+static const struct platform_s2idle_ops rpmh_rsc_s2idle_ops = {
+	.begin = rpmh_rsc_s2idle_begin,
+	.prepare_late = rpmh_rsc_s2idle_prepare_late,
+};
+
 static int rpmh_rsc_probe(struct platform_device *pdev)
 {
 	struct device_node *dn = pdev->dev.of_node;
@@ -1122,6 +1142,9 @@ static int rpmh_rsc_probe(struct platform_device *pdev)
 	dev_set_drvdata(&pdev->dev, drv);
 	drv->dev = &pdev->dev;
 
+	if (of_machine_is_compatible("qcom,sc8280xp"))
+		s2idle_set_ops(&rpmh_rsc_s2idle_ops);
+
 	ret = devm_of_platform_populate(&pdev->dev);
 	if (ret && pdev->dev.pm_domain) {
 		dev_pm_genpd_remove_notifier(&pdev->dev);
-- 
2.48.1