ACPI: Add acpi_pm_device_sleep_state helper routine
Based on the David Brownell's patch at
http://marc.info/?l=linux-acpi&m=117873972806360&w=2
updated by: Rafael J. Wysocki <rjw@sisk.pl>
Add a helper routine returning the lowest power (highest number) ACPI device
power state that given device can be in while the system is in the sleep state
indicated by acpi_target_sleep_state .
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c
index 19f8557..55eca6e 100644
--- a/drivers/acpi/sleep/main.c
+++ b/drivers/acpi/sleep/main.c
@@ -260,6 +260,81 @@
};
#endif /* CONFIG_SOFTWARE_SUSPEND */
+/**
+ * acpi_pm_device_sleep_state - return preferred power state of ACPI device
+ * in the system sleep state given by %acpi_target_sleep_state
+ * @dev: device to examine
+ * @wake: if set, the device should be able to wake up the system
+ * @d_min_p: used to store the upper limit of allowed states range
+ * Return value: preferred power state of the device on success, -ENODEV on
+ * failure (ie. if there's no 'struct acpi_device' for @dev)
+ *
+ * Find the lowest power (highest number) ACPI device power state that
+ * device @dev can be in while the system is in the sleep state represented
+ * by %acpi_target_sleep_state. If @wake is nonzero, the device should be
+ * able to wake up the system from this sleep state. If @d_min_p is set,
+ * the highest power (lowest number) device power state of @dev allowed
+ * in this system sleep state is stored at the location pointed to by it.
+ *
+ * The caller must ensure that @dev is valid before using this function.
+ * The caller is also responsible for figuring out if the device is
+ * supposed to be able to wake up the system and passing this information
+ * via @wake.
+ */
+
+int acpi_pm_device_sleep_state(struct device *dev, int wake, int *d_min_p)
+{
+ acpi_handle handle = DEVICE_ACPI_HANDLE(dev);
+ struct acpi_device *adev;
+ char acpi_method[] = "_SxD";
+ unsigned long d_min, d_max;
+
+ if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev))) {
+ printk(KERN_ERR "ACPI handle has no context!\n");
+ return -ENODEV;
+ }
+
+ acpi_method[2] = '0' + acpi_target_sleep_state;
+ /*
+ * If the sleep state is S0, we will return D3, but if the device has
+ * _S0W, we will use the value from _S0W
+ */
+ 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 (acpi_target_sleep_state > ACPI_STATE_S0)
+ acpi_evaluate_integer(handle, acpi_method, NULL, &d_min);
+
+ /*
+ * 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 (acpi_target_sleep_state == ACPI_STATE_S0 ||
+ (wake && adev->wakeup.state.enabled &&
+ adev->wakeup.sleep_state <= acpi_target_sleep_state)) {
+ acpi_method[3] = 'W';
+ acpi_evaluate_integer(handle, acpi_method, NULL, &d_max);
+ /* Sanity check */
+ if (d_max < d_min)
+ d_min = d_max;
+ }
+
+ if (d_min_p)
+ *d_min_p = d_min;
+ return d_max;
+}
+
/*
* Toshiba fails to preserve interrupts over S1, reinitialization
* of 8259 is needed after S1 resume.