ACPI / PM: Introduce os_accessible flag for power_state

Currently we have valid flag to represent if this ACPI device power
state is valid. A device power state is valid does not necessarily
mean we, as OSPM, has a mean to put the device into that power state,
e.g. D3 cold is always a valid power state for any ACPI device, but if
there is no _PS3 or _PRx for this device, we can't really put that
device into D3 cold power state. The same is true for D0 power state.

So here comes the os_accessible flag, which is only set if the device
has provided us the required means to put it into that power state,
e.g. if we have _PS3 or _PRx, we can put the device into D3 cold state
and thus, D3 cold power state's os_accessible flag will be set in this
case.

And a new wrapper inline function is added to be used to check if
firmware has provided us a way to power off the device during runtime.

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 1fcb8678665c..da1416af0c8b 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -965,8 +965,10 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
                  * D3hot is only valid if _PR3 present.
                  */
                 if (ps->resources.count ||
-                    (ps->flags.explicit_set && i < ACPI_STATE_D3_HOT))
+                    (ps->flags.explicit_set && i < ACPI_STATE_D3_HOT)) {
                         ps->flags.valid = 1;
+                        ps->flags.os_accessible = 1;
+                }
 
                 ps->power = -1; /* Unknown - driver assigned */
                 ps->latency = -1;       /* Unknown - driver assigned */
@@ -982,6 +984,11 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
         if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set)
                 device->power.states[ACPI_STATE_D3_COLD].flags.explicit_set = 1;
 
+        /* Presence of _PS3 or _PRx means we can put the device into D3 cold */
+        if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set ||
+                        device->power.flags.power_resources)
+                device->power.states[ACPI_STATE_D3_COLD].flags.os_accessible = 1;
+
         acpi_bus_init_power(device);
 
         return 0;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 80155fda517f..c3bc4511e0c0 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -201,6 +201,7 @@ struct acpi_device_power_flags {
 struct acpi_device_power_state {
         struct {
                 u8 valid:1;
+                u8 os_accessible:1;
                 u8 explicit_set:1;      /* _PSx present? */
                 u8 reserved:6;
         } flags;
@@ -500,6 +501,11 @@ static inline bool acpi_device_can_wakeup(struct acpi_device *adev)
         return adev->wakeup.flags.valid;
 }
 
+static inline bool acpi_device_can_poweroff(struct acpi_device *adev)
+{
+        return adev->power.states[ACPI_STATE_D3_COLD].flags.os_accessible;
+}
+
 #else   /* CONFIG_ACPI */
 
 static inline int register_acpi_bus_type(void *bus) { return 0; }