Enter power-saving mode on POWER9 (ISA v3)

When opal(4) attaches, look in the device tree for a psscr value.  In
cpu_idle_cycle(), use this psscr value and the stop instruction to
wait for the next interrupt.  In mp kernels, cpu_unidle() now sends an
interrupt.  In "sysctl hw.sensors", the power and temperature sensors
from opalsens(4) may show lower values.

The cpu may exit stop at the system reset vector after losing user
registers.  If so, restore some registers.  For now, ignore deeper
stop states that would lose hypervisor registers.

Our mp kernel uses only the first hardware thread of each core.  Take
the extra threads from the firmware and stop them forever; this may
switch the core from SMT4 to single-thread mode and increase
performance.

partly by kettenis@, ok kettenis@

2 files changed, 19 insertions, 2 deletions

diff --git a/sys/dev/ofw/fdt.c b/sys/dev/ofw/fdt.c
index 9646d74eeb8..62ca7392c45 100644
--- a/sys/dev/ofw/fdt.c
+++ b/sys/dev/ofw/fdt.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fdt.c,v 1.25 2020/07/18 09:44:59 kettenis Exp $	*/
+/*	$OpenBSD: fdt.c,v 1.26 2020/12/30 06:06:31 gkoehler Exp $	*/
 
 /*
  * Copyright (c) 2009 Dariusz Swiderski <sfires@sfires.net>
@@ -1005,6 +1005,22 @@ OF_getpropint64(int handle, char *prop, uint64_t defval)
 }
 
 int
+OF_getpropint64array(int handle, char *prop, uint64_t *buf, int buflen)
+{
+	int len;
+	int i;
+
+	len = OF_getprop(handle, prop, buf, buflen);
+	if (len < 0 || (len % sizeof(uint64_t)))
+		return -1;
+
+	for (i = 0; i < len / sizeof(uint64_t); i++)
+		buf[i] = betoh64(buf[i]);
+
+	return len;
+}
+
+int
 OF_nextprop(int handle, char *prop, void *nextprop)
 {
 	void *node = (char *)tree.header + handle;
diff --git a/sys/dev/ofw/openfirm.h b/sys/dev/ofw/openfirm.h
index 57022b05c85..ea631c2f0e4 100644
--- a/sys/dev/ofw/openfirm.h
+++ b/sys/dev/ofw/openfirm.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: openfirm.h,v 1.16 2020/07/06 15:18:03 kettenis Exp $	*/
+/*	$OpenBSD: openfirm.h,v 1.17 2020/12/30 06:06:31 gkoehler Exp $	*/
 /*	$NetBSD: openfirm.h,v 1.1 1996/09/30 16:35:10 ws Exp $	*/
 
 /*
@@ -53,6 +53,7 @@ int OF_getprop(int handle, char *prop, void *buf, int buflen);
 uint32_t OF_getpropint(int handle, char *, uint32_t);
 int OF_getpropintarray(int, char *, uint32_t *, int);
 uint64_t OF_getpropint64(int handle, char *, uint64_t);
+int OF_getpropint64array(int, char *, uint64_t *, int);
 int OF_setprop(int, char *, const void *, int);
 int OF_nextprop(int, char *, void *);
 int OF_finddevice(char *name);