ACPI / PM: Add function for updating device power state consistently

Add function acpi_bus_update_power() for reading the actual power
state of an ACPI device and updating its device->power.state field
in such a way that its power resources' reference counters will
remain consistent with that field.

For this purpose introduce __acpi_bus_set_power() setting the
power state of an ACPI device without updating its
device->power.state field and make acpi_bus_set_power() and
acpi_bus_update_power() use it (acpi_bus_set_power() retains the
current behavior for now).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 61 insertions, 29 deletions

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 453451090502..19decee72e92 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -255,44 +255,17 @@ int acpi_bus_get_power(acpi_handle handle, int *state)
 EXPORT_SYMBOL(acpi_bus_get_power);
 
 
-int acpi_bus_set_power(acpi_handle handle, int state)
+static int __acpi_bus_set_power(struct acpi_device *device, int state)
 {
         int result = 0;
         acpi_status status = AE_OK;
-        struct acpi_device *device = NULL;
         char object_name[5] = { '_', 'P', 'S', '0' + state, '\0' };
 
-
-        result = acpi_bus_get_device(handle, &device);
-        if (result)
-                return result;
-
-        if ((state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
+        if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
                 return -EINVAL;
 
         /* Make sure this is a valid target state */
 
-        if (!device->flags.power_manageable) {
-                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device `[%s]' is not power manageable\n",
-                                kobject_name(&device->dev.kobj)));
-                return -ENODEV;
-        }
-        /*
-         * Get device's current power state
-         */
-        if (!acpi_power_nocheck) {
-                /*
-                 * Maybe the incorrect power state is returned on the bogus
-                 * bios, which is different with the real power state.
-                 * For example: the bios returns D0 state and the real power
-                 * state is D3. OS expects to set the device to D0 state. In
-                 * such case if OS uses the power state returned by the BIOS,
-                 * the device can't be transisted to the correct power state.
-                 * So if the acpi_power_nocheck is set, it is unnecessary to
-                 * get the power state by calling acpi_bus_get_power.
-                 */
-                acpi_bus_get_power(device->handle, &device->power.state);
-        }
         if ((state == device->power.state) && !device->flags.force_power_state) {
                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device is already at D%d\n",
                                   state));
@@ -362,6 +335,42 @@ int acpi_bus_set_power(acpi_handle handle, int state)
         return result;
 }
 
+
+int acpi_bus_set_power(acpi_handle handle, int state)
+{
+        struct acpi_device *device;
+        int result;
+
+        result = acpi_bus_get_device(handle, &device);
+        if (result)
+                return result;
+
+        if (!device->flags.power_manageable) {
+                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+                                "Device [%s] is not power manageable\n",
+                                dev_name(&device->dev)));
+                return -ENODEV;
+        }
+
+        /*
+         * Get device's current power state
+         */
+        if (!acpi_power_nocheck) {
+                /*
+                 * Maybe the incorrect power state is returned on the bogus
+                 * bios, which is different with the real power state.
+                 * For example: the bios returns D0 state and the real power
+                 * state is D3. OS expects to set the device to D0 state. In
+                 * such case if OS uses the power state returned by the BIOS,
+                 * the device can't be transisted to the correct power state.
+                 * So if the acpi_power_nocheck is set, it is unnecessary to
+                 * get the power state by calling acpi_bus_get_power.
+                 */
+                __acpi_bus_get_power(device, &device->power.state);
+        }
+
+        return __acpi_bus_set_power(device, state);
+}
 EXPORT_SYMBOL(acpi_bus_set_power);
 
 
@@ -389,6 +398,29 @@ int acpi_bus_init_power(struct acpi_device *device)
 }
 
 
+int acpi_bus_update_power(acpi_handle handle, int *state_p)
+{
+        struct acpi_device *device;
+        int state;
+        int result;
+
+        result = acpi_bus_get_device(handle, &device);
+        if (result)
+                return result;
+
+        result = __acpi_bus_get_power(device, &state);
+        if (result)
+                return result;
+
+        result = __acpi_bus_set_power(device, state);
+        if (!result && state_p)
+                *state_p = state;
+
+        return result;
+}
+EXPORT_SYMBOL_GPL(acpi_bus_update_power);
+
+
 bool acpi_bus_power_manageable(acpi_handle handle)
 {
         struct acpi_device *device;