diff options
Diffstat (limited to 'drivers/acpi')
| -rw-r--r-- | drivers/acpi/sleep/main.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c index 19f8557c711..55eca6eabcd 100644 --- a/drivers/acpi/sleep/main.c +++ b/drivers/acpi/sleep/main.c @@ -260,6 +260,81 @@ static struct hibernation_ops acpi_hibernation_ops = { }; #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. |