Since two new sysfs interface files are created for umwait control, add
an ABI document entry for the files:
        /sys/devices/system/cpu/umwait_control/enable_c02
        /sys/devices/system/cpu/umwait_control/max_time

Signed-off-by: Fenghua Yu <fenghua...@intel.com>
Reviewed-by: Ashok Raj <ashok....@intel.com>
---
 .../ABI/testing/sysfs-devices-system-cpu      | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu 
b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 1528239f69b2..d22cdadd3161 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -538,3 +538,24 @@ Description:       Intel Energy and Performance Bias Hint 
(EPB)
 
                This attribute is present for all online CPUs supporting the
                Intel EPB feature.
+
+What:          /sys/devices/system/cpu/umwait_control
+               /sys/devices/system/cpu/umwait_control/enable_c02
+               /sys/devices/system/cpu/umwait_control/max_time
+Date:          May 2019
+Contact:       Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:   Umwait control
+
+               enable_c02: Read/write interface to control umwait C0.2 state
+                       Read returns C0.2 state status:
+                               0: C0.2 is disabled
+                               1: C0.2 is enabled
+
+                       Write 'Yy1' or [oO][nN] for on to enable C0.2 state.
+                       Write 'Nn0' or [oO][fF] for off to disable C0.2 state.
+
+               max_time: Read/write interface to control umwait maximum time
+                         in TSC-quanta that the CPU can reside in either C0.1
+                         or C0.2 state. The time is an unsigned 32-bit number.
+                         Note that a value of zero means there is no limit.
+                         Low order two bits must be zero.
-- 
2.19.1

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