[PATCH 12/18] drivers: firmware: psci: Add a helper to attach a CPU to its PM domain

[Ulf Hansson]

Introduce a new PSCI DT helper function, psci_dt_attach_cpu(), which takes
a CPU number as an in-parameter and tries to attach the CPU's struct device
to its corresponding PM domain. Let's use dev_pm_domain_attach_by_name(),
as to be able to specify "psci" as the required "power-domain-names".

Additionally, let the helper prepare the CPU to be power managed via
runtime PM.

Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---

Changes:
	- Take into account whether the CPU is online/offline.
	- Convert from dev_pm_domain_attach() into using the more future proof
	  dev_pm_domain_attach_by_name().

---
 drivers/firmware/psci/psci.h           |  3 +++
 drivers/firmware/psci/psci_pm_domain.c | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/firmware/psci/psci.h b/drivers/firmware/psci/psci.h
index c36e0e6649e9..b4254405b8ef 100644
--- a/drivers/firmware/psci/psci.h
+++ b/drivers/firmware/psci/psci.h
@@ -4,6 +4,7 @@
 #define __PSCI_H
 
 struct cpuidle_driver;
+struct device;
 struct device_node;
 
 int psci_set_osi_mode(void);
@@ -16,10 +17,12 @@ int psci_dt_parse_state_node(struct device_node *np, u32 *state);
 int psci_dt_init_pm_domains(struct device_node *np);
 int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
 		struct device_node *cpu_node, u32 *psci_states);
+struct device *psci_dt_attach_cpu(int cpu);
 #else
 static inline int psci_dt_init_pm_domains(struct device_node *np) { return 0; }
 static inline int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
 		struct device_node *cpu_node, u32 *psci_states) { return 0; }
+static inline struct device *psci_dt_attach_cpu(int cpu) { return NULL; }
 #endif
 #endif
 
diff --git a/drivers/firmware/psci/psci_pm_domain.c b/drivers/firmware/psci/psci_pm_domain.c
index 3aa645dba81b..1cbe745ee001 100644
--- a/drivers/firmware/psci/psci_pm_domain.c
+++ b/drivers/firmware/psci/psci_pm_domain.c
@@ -12,8 +12,10 @@
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/cpu.h>
 #include <linux/cpuidle.h>
 #include <linux/cpu_pm.h>
 
@@ -383,4 +385,19 @@ int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
 
 	return 0;
 }
+
+struct device *psci_dt_attach_cpu(int cpu)
+{
+	struct device *dev, *cpu_dev = get_cpu_device(cpu);
+
+	dev = dev_pm_domain_attach_by_name(cpu_dev, "psci");
+	if (IS_ERR_OR_NULL(dev))
+		return dev;
+
+	pm_runtime_irq_safe(dev);
+	if (cpu_online(cpu))
+		pm_runtime_get_sync(dev);
+
+	return dev;
+}
 #endif
-- 
2.17.1