ACPI / PM: Move device power state selection routine to device_pm.c

The ACPI function for choosing device power state is now located
in drivers/acpi/sleep.c, but drivers/acpi/device_pm.c is a more
logical place for it, so move it there.

However, instead of moving the function entirely, move its core only
under a different name and with a different list of arguments, so
that it is more flexible, and leave a wrapper around it in the
original location.

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

1 files changed, 107 insertions, 0 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 2d2e0bc8891b..c017b801171c 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -23,7 +23,9 @@
  */
 
 #include <linux/device.h>
+#include <linux/export.h>
 #include <linux/mutex.h>
+#include <linux/pm_qos.h>
 
 #include <acpi/acpi.h>
 #include <acpi/acpi_bus.h>
@@ -89,3 +91,108 @@ acpi_status acpi_remove_pm_notifier(struct acpi_device *adev,
 	mutex_unlock(&acpi_pm_notifier_lock);
 	return status;
 }
+
+/**
+ * acpi_device_power_state - Get preferred power state of ACPI device.
+ * @dev: Device whose preferred target power state to return.
+ * @adev: ACPI device node corresponding to @dev.
+ * @target_state: System state to match the resultant device state.
+ * @d_max_in: Deepest low-power state to take into consideration.
+ * @d_min_p: Location to store the upper limit of the allowed states range.
+ * Return value: Preferred power state of the device on success, -ENODEV
+ * (if there's no 'struct acpi_device' for @dev) or -EINVAL on failure
+ *
+ * Find the lowest power (highest number) ACPI device power state that the
+ * device can be in while the system is in the state represented by
+ * @target_state.  If @d_min_p is set, the highest power (lowest number) device
+ * power state that @dev can be in for the given system sleep state is stored
+ * at the location pointed to by it.
+ *
+ * Callers must ensure that @dev and @adev are valid pointers and that @adev
+ * actually corresponds to @dev before using this function.
+ */
+int acpi_device_power_state(struct device *dev, struct acpi_device *adev,
+			    u32 target_state, int d_max_in, int *d_min_p)
+{
+	char acpi_method[] = "_SxD";
+	unsigned long long d_min, d_max;
+	bool wakeup = false;
+
+	if (d_max_in < ACPI_STATE_D0 || d_max_in > ACPI_STATE_D3)
+		return -EINVAL;
+
+	if (d_max_in > ACPI_STATE_D3_HOT) {
+		enum pm_qos_flags_status stat;
+
+		stat = dev_pm_qos_flags(dev, PM_QOS_FLAG_NO_POWER_OFF);
+		if (stat == PM_QOS_FLAGS_ALL)
+			d_max_in = ACPI_STATE_D3_HOT;
+	}
+
+	acpi_method[2] = '0' + target_state;
+	/*
+	 * If the sleep state is S0, the lowest limit from ACPI is D3,
+	 * but if the device has _S0W, we will use the value from _S0W
+	 * as the lowest limit from ACPI.  Finally, we will constrain
+	 * the lowest limit with the specified one.
+	 */
+	d_min = ACPI_STATE_D0;
+	d_max = ACPI_STATE_D3;
+
+	/*
+	 * If present, _SxD methods return the minimum D-state (highest power
+	 * state) we can use for the corresponding S-states.  Otherwise, the
+	 * minimum D-state is D0 (ACPI 3.x).
+	 *
+	 * NOTE: We rely on acpi_evaluate_integer() not clobbering the integer
+	 * provided -- that's our fault recovery, we ignore retval.
+	 */
+	if (target_state > ACPI_STATE_S0) {
+		acpi_evaluate_integer(adev->handle, acpi_method, NULL, &d_min);
+		wakeup = device_may_wakeup(dev) && adev->wakeup.flags.valid
+			&& adev->wakeup.sleep_state >= target_state;
+	} else if (dev_pm_qos_flags(dev, PM_QOS_FLAG_REMOTE_WAKEUP) !=
+			PM_QOS_FLAGS_NONE) {
+		wakeup = adev->wakeup.flags.valid;
+	}
+
+	/*
+	 * If _PRW says we can wake up the system from the target sleep state,
+	 * the D-state returned by _SxD is sufficient for that (we assume a
+	 * wakeup-aware driver if wake is set).  Still, if _SxW exists
+	 * (ACPI 3.x), it should return the maximum (lowest power) D-state that
+	 * can wake the system.  _S0W may be valid, too.
+	 */
+	if (wakeup) {
+		acpi_status status;
+
+		acpi_method[3] = 'W';
+		status = acpi_evaluate_integer(adev->handle, acpi_method, NULL,
+						&d_max);
+		if (ACPI_FAILURE(status)) {
+			if (target_state != ACPI_STATE_S0 ||
+			    status != AE_NOT_FOUND)
+				d_max = d_min;
+		} else if (d_max < d_min) {
+			/* Warn the user of the broken DSDT */
+			printk(KERN_WARNING "ACPI: Wrong value from %s\n",
+				acpi_method);
+			/* Sanitize it */
+			d_min = d_max;
+		}
+	}
+
+	if (d_max_in < d_min)
+		return -EINVAL;
+	if (d_min_p)
+		*d_min_p = d_min;
+	/* constrain d_max with specified lowest limit (max number) */
+	if (d_max > d_max_in) {
+		for (d_max = d_max_in; d_max > d_min; d_max--) {
+			if (adev->power.states[d_max].flags.valid)
+				break;
+		}
+	}
+	return d_max;
+}
+EXPORT_SYMBOL_GPL(acpi_device_power_state);