From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Subject: ACPI / PM: Export power states of ACPI devices via sysfs
Make it possible to retrieve the current power state of a device with
ACPI power management from user space via sysfs by adding a new
attribute power_state to the sysfs directory associated with the
struct acpi_device object representing the device's ACPI node.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
I've changed my mind here. It looks like it's more convenient to put the
power_state attribute directly into the ACPI device node's directory in sysfs
rather than into its power subdirectory.
Thanks,
Rafael
---
Documentation/ABI/testing/sysfs-devices-power | 13 +++++++++++++
drivers/acpi/scan.c | 25 ++++++++++++++++++++++++-
2 files changed, 37 insertions(+), 1 deletion(-)
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -184,6 +184,19 @@ err_out:
}
EXPORT_SYMBOL(acpi_bus_hot_remove_device);
+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 ssize_t
acpi_eject_store(struct device *d, struct device_attribute *attr,
const char *buf, size_t count)
@@ -375,8 +388,15 @@ static int acpi_device_setup_files(struc
* hot-removal function from userland.
*/
status = acpi_get_handle(dev->handle, "_EJ0", &temp);
- if (ACPI_SUCCESS(status))
+ if (ACPI_SUCCESS(status)) {
result = device_create_file(&dev->dev, &dev_attr_eject);
+ if (result)
+ goto end;
+ }
+
+ if (dev->flags.power_manageable)
+ result = device_create_file(&dev->dev, &dev_attr_power_state);
+
end:
return result;
}
@@ -386,6 +406,9 @@ static void acpi_device_remove_files(str
acpi_status status;
acpi_handle temp;
+ if (dev->flags.power_manageable)
+ device_remove_file(&dev->dev, &dev_attr_power_state);
+
/*
* If device has _STR, remove 'description' file
*/
--
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