Document the hw.battery sysctls.

ok benno@, jmc@, schwarze@

diff --git a/lib/libc/sys/sysctl.2 b/lib/libc/sys/sysctl.2
index 31bef7d..78c69ff 100644 (file)
--- a/lib/libc/sys/sysctl.2
+++ b/lib/libc/sys/sysctl.2
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: sysctl.2,v 1.56 2023/10/12 12:56:26 schwarze Exp $
+.\"    $OpenBSD: sysctl.2,v 1.57 2023/10/14 19:02:16 kettenis Exp $
 .\"
 .\" Copyright (c) 1993
 .\"    The Regents of the University of California.  All rights reserved.
@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: October 12 2023 $
+.Dd $Mdocdate: October 14 2023 $
 .Dt SYSCTL 2
 .Os
 .Sh NAME
@@ -277,6 +277,7 @@ privileges may change the value.
 .Bl -column "Second level name" "integer" "Changeable" -offset indent
 .It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable"
 .It Dv HW_ALLOWPOWERDOWN Ta "integer" Ta "yes"
+.It Dv HW_BATTERY Ta "node" Ta "not applicable"
 .It Dv HW_BYTEORDER Ta "integer" Ta "no"
 .It Dv HW_CPUSPEED Ta "integer" Ta "no"
 .It Dv HW_DISKCOUNT Ta "integer" Ta "no"
@@ -313,6 +314,42 @@ When running with a
 .Xr securelevel 7
 greater than 0,
 this variable may not be changed.
+.It Dv HW_BATTERY Pq Va hw.battery
+Control battery charging.
+These are only available on hardware that supports battery charging control.
+There are three subnodes:
+.Bl -column "HW_BATTERY_CHARGESTART" "integer" "Changeable" -offset indent
+.It Sy "Third level name" Ta Sy "Type" Ta Sy "Changeable"
+.It Dv HW_BATTERY_CHARGEMODE Ta "integer" Ta "yes"
+.It Dv HW_BATTERY_CHARGESTART Ta "integer" Ta "maybe"
+.It Dv HW_BATTERY_CHARGESTOP Ta "integer" Ta "yes"
+.El
+.Pp
+Their meanings are as follows:
+.Bl -tag -width "123456"
+.It Dv HW_BATTERY_CHARGEMODE Pq Va hw.battery.chargemode
+Control if the battery is charged or discharged.
+A value of -1 means to (forcibly) discharge the battery.
+A value of 0 means to inhibit charging the battery.
+A value of 1 means to charge the battery, subject to the configured limits.
+.It Dv HW_BATTERY_CHARGESTART Pq Va hw.battery.chargestart
+The percentage below which the battery will start charging.
+Not all hardware allows setting this value.
+On hardware that does not allow setting this value the battery will typically
+start charging at a fixed percentage point below the value configured through
+.Dv HW_BATTERY_CHARGESTOP .
+.It Dv HW_BATTERY_CHARGESTOP Pq Va hw.battery.chargestop
+The percentage above which the battery will stop charging.
+Setting the value to 100 will fully charge the battery.
+.El
+.Pp
+By setting
+.Dv HW_BATTERY_CHARGEMODE
+to 1, and setting both
+.Dv HW_BATTERY_CHARGESTART
+and
+.Dv HW_BATTERY_CHARGESTOP ,
+the battery will be kept charged at a percentage between the configured limits.
 .It Dv HW_BYTEORDER Pq Va hw.byteorder
 The byteorder (4321 or 1234).
 .It Dv HW_CPUSPEED Pq Va hw.cpuspeed