ACPI: sysfs: Update device object sysfs documentation

Add documentation for two attributes, status and hrv, in
Documentation/ABI/testing/sysfs-bus-acpi.

Compiled from git logs and the ACPI specification.

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
[ rjw: Minor changes ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-acpi b/Documentation/ABI/testing/sysfs-bus-acpi
index 7fa9cbc75344..e7898cfe5fb1 100644
--- a/Documentation/ABI/testing/sysfs-bus-acpi
+++ b/Documentation/ABI/testing/sysfs-bus-acpi
@@ -56,3 +56,40 @@ Description:
                 Writing 1 to this attribute will trigger hot removal of
                 this device object.  This file exists for every device
                 object that has _EJ0 method.
+
+What:           /sys/bus/acpi/devices/.../status
+Date:           Jan, 2014
+Contact:        Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+                (RO) Returns the ACPI device status: enabled, disabled or
+                functioning or present, if the method _STA is present.
+
+                The return value is a decimal integer representing the device's
+                status bitmap:
+
+                Bit [0] –  Set if the device is present.
+                Bit [1] –  Set if the device is enabled and decoding its
+                           resources.
+                Bit [2] –  Set if the device should be shown in the UI.
+                Bit [3] –  Set if the device is functioning properly (cleared if
+                           device failed its diagnostics).
+                Bit [4] –  Set if the battery is present.
+                Bits [31:5] –  Reserved (must be cleared)
+
+                If bit [0] is clear, then bit 1 must also be clear (a device
+                that is not present cannot be enabled).
+
+                Bit 0 can be clear (not present) with bit [3] set (device is
+                functional).  This case is used to indicate a valid device for
+                which no device driver should be loaded.
+
+                More special cases are covered in the ACPI specification.
+
+What:           /sys/bus/acpi/devices/.../hrv
+Date:           Apr, 2016
+Contact:        Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+                (RO) Allows users to read the hardware version of non-PCI
+                hardware, if the _HRV control method is present.  It is mostly
+                useful for non-PCI devices because lspci can list the hardware
+                version for PCI devices.