[PATCH v2 10/13] cpuidle: psci: Prepare to use OS initiated suspend mode via PM domains

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

The per CPU variable psci_power_state, contains an array of fixed values,
which reflects the corresponding arm,psci-suspend-param parsed from DT, for
each of the available CPU idle states.

This isn't sufficient when using the hierarchical CPU topology in DT, in
combination with having PSCI OS initiated (OSI) mode enabled. More
precisely, in OSI mode, Linux is responsible of telling the PSCI FW what
idle state the cluster (a group of CPUs) should enter, while in PSCI
Platform Coordinated (PC) mode, each CPU independently votes for an idle
state of the cluster.

For this reason, introduce a per CPU variable called domain_state and
implement two helper functions to read/write its value. Then let the
domain_state take precedence over the regular selected state, when entering
and idle state.

Finally, let's also avoid sprinkling the existing non-OSI path with
operations being specific for OSI.

Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v2:
	- Rebased.

---
 drivers/cpuidle/cpuidle-psci.c | 47 +++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index 167249d0493f..4b0183d010e0 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -29,14 +29,55 @@ struct psci_cpuidle_data {
 };
 
 static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
+static DEFINE_PER_CPU(u32, domain_state);
+
+static inline void psci_set_domain_state(u32 state)
+{
+	__this_cpu_write(domain_state, state);
+}
+
+static inline u32 psci_get_domain_state(void)
+{
+	return __this_cpu_read(domain_state);
+}
+
+static inline int _psci_enter_state(int idx, u32 state)
+{
+	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
+}
+
+static int psci_enter_domain_state(int idx, struct psci_cpuidle_data *data)
+{
+	int ret;
+	u32 *states = data->psci_states;
+	u32 state = psci_get_domain_state();
+
+	if (!state)
+		state = states[idx];
+
+	ret = _psci_enter_state(idx, state);
+
+	/* Clear the domain state to start fresh when back from idle. */
+	psci_set_domain_state(0);
+	return ret;
+}
+
+static int psci_enter_state(int idx, struct psci_cpuidle_data *data)
+{
+	u32 *states = data->psci_states;
+
+	return _psci_enter_state(idx, states[idx]);
+}
 
 static int psci_enter_idle_state(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int idx)
 {
-	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
+	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
+
+	if (!data->dev)
+		return psci_enter_state(idx, data);
 
-	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
-					   idx, state[idx]);
+	return psci_enter_domain_state(idx, data);
 }
 
 static struct cpuidle_driver psci_idle_driver __initdata = {
-- 
2.17.1