From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Make it possible to retrieve the current power state of an ACPI
device from user space via sysfs by adding a new attribute
power_state to the power subdirectory of the sysfs directory
associated with the struct acpi_device representing the device's
ACPI node.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-devices-power | 13 ++++++++
drivers/acpi/scan.c | 41 ++++++++++++++++++++++++++
2 files changed, 54 insertions(+)
Index: linux/drivers/acpi/scan.c
===================================================================
--- linux.orig/drivers/acpi/scan.c
+++ linux/drivers/acpi/scan.c
@@ -184,6 +184,43 @@ err_out:
}
EXPORT_SYMBOL(acpi_bus_hot_remove_device);
+#ifdef CONFIG_PM
+static ssize_t power_state_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct acpi_device *adev = to_acpi_device(dev);
+ int state;
+ int ret;
+
+ ret = acpi_device_get_power(adev, &state);
+ return ret ? ret : sprintf(buf, "%s\n", acpi_power_state_string(state));
+}
+
+static DEVICE_ATTR(power_state, 0444, power_state_show, NULL);
+
+static struct attribute *acpi_dev_pm_attrs[] = {
+ &dev_attr_power_state.attr,
+ NULL,
+};
+static struct attribute_group acpi_dev_pm_attr_group = {
+ .name = power_group_name,
+ .attrs = acpi_dev_pm_attrs,
+};
+
+static void acpi_dev_pm_sysfs_add(struct device *dev)
+{
+ sysfs_merge_group(&dev->kobj, &acpi_dev_pm_attr_group);
+}
+
+static void acpi_dev_pm_sysfs_remove(struct device *dev)
+{
+ sysfs_unmerge_group(&dev->kobj, &acpi_dev_pm_attr_group);
+}
+#else /* !CONFIG_PM */
+static inline void acpi_dev_pm_sysfs_add(struct device *dev) {}
+static inline void acpi_dev_pm_sysfs_remove(struct device *dev) {}
+#endif /* !CONFIG_PM */
+
static ssize_t
acpi_eject_store(struct device *d, struct device_attribute *attr,
const char *buf, size_t count)
@@ -377,6 +414,9 @@ static int acpi_device_setup_files(struc
status = acpi_get_handle(dev->handle, "_EJ0", &temp);
if (ACPI_SUCCESS(status))
result = device_create_file(&dev->dev, &dev_attr_eject);
+
+ acpi_dev_pm_sysfs_add(&dev->dev);
+
end:
return result;
}
@@ -386,6 +426,7 @@ static void acpi_device_remove_files(str
acpi_status status;
acpi_handle temp;
+ acpi_dev_pm_sysfs_remove(&dev->dev);
/*
* If device has _STR, remove 'description' file
*/
Index: linux/Documentation/ABI/testing/sysfs-devices-power
===================================================================
--- linux.orig/Documentation/ABI/testing/sysfs-devices-power
+++ linux/Documentation/ABI/testing/sysfs-devices-power
@@ -235,3 +235,16 @@ Description:
This attribute has no effect on system-wide suspend/resume and
hibernation.
+
+What: /sys/devices/.../power/power_state
+Date: December 2012
+Contact: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
+Description:
+ The /sys/devices/.../power/power_state attribute is only present
+ for ACPI device nodes (i.e. objects of type struct acpi_device).
+
+ If present, it contains the string representation of the current
+ ACPI power state of the device represented by the given ACPI
+ device node.
+
+ This attribute is read-only.
--
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