PM / Domains: Add dev_pm_domain_attach_by_id() to manage multi PM domains

The existing dev_pm_domain_attach() function, allows a single PM domain to
be attached per device. To be able to support devices that are partitioned
across multiple PM domains, let's introduce a new interface,
dev_pm_domain_attach_by_id().

The dev_pm_domain_attach_by_id() returns a new allocated struct device with
the corresponding attached PM domain. This enables for example a driver to
operate on the new device from a power management point of view. The driver
may then also benefit from using the received device, to set up so called
device-links towards its original device. Depending on the situation, these
links may then be dynamically changed.

The new interface is typically called by drivers during their probe phase,
in case they manages devices which uses multiple PM domains. If that is the
case, the driver also becomes responsible of managing the detaching of the
PM domains, which typically should be done at the remove phase. Detaching
is done by calling the existing dev_pm_domain_detach() function and for
each of the received devices from dev_pm_domain_attach_by_id().

Note, currently its only genpd that supports multiple PM domains per
device, but dev_pm_domain_attach_by_id() can easily by extended to cover
other PM domain types, if/when needed.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 82458e8e2e01..9206a4fef9ac 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -299,6 +299,8 @@ struct generic_pm_domain *of_genpd_remove_last(struct device_node *np)
 
 #ifdef CONFIG_PM
 int dev_pm_domain_attach(struct device *dev, bool power_on);
+struct device *dev_pm_domain_attach_by_id(struct device *dev,
+					  unsigned int index);
 void dev_pm_domain_detach(struct device *dev, bool power_off);
 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd);
 #else
@@ -306,6 +308,11 @@ static inline int dev_pm_domain_attach(struct device *dev, bool power_on)
 {
 	return 0;
 }
+static inline struct device *dev_pm_domain_attach_by_id(struct device *dev,
+							unsigned int index)
+{
+	return NULL;
+}
 static inline void dev_pm_domain_detach(struct device *dev, bool power_off) {}
 static inline void dev_pm_domain_set(struct device *dev,
 				     struct dev_pm_domain *pd) {}