# HG changeset patch
# User Robert Ransom <rransom.8774@gmail.com>
# Date 1578147960 18000
# Node ID 48a158c0731b26c142a404cc3fdd04e679a3bca1
# Parent  939ab197463703d4835622103bde410bd0a2acd7
Add minimal CPU frequency support for AMD family 10h and later

This uses the 'hardware P-state control' present through the
current family 17h processors.  Family 10h also has the registers
for the older software COF/VID control mechanism required by family
0fh (and earlier?), so this really ought to be generalized to
support more than one type of CPU frequency control on the same
system.

diff --git a/sys/src/9/pc/cpufreq.c b/sys/src/9/pc/cpufreq.c
new file mode 100644
--- /dev/null
+++ b/sys/src/9/pc/cpufreq.c
@@ -0,0 +1,97 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "io.h"
+#include "../port/error.h"
+
+enum {
+	CMpowersave,
+};
+
+static Cmdtab amdpstatectlmsg[] = {
+	CMpowersave,	"powersave",	1,
+};
+
+static int
+amdpstatecpufreqok(void)
+{
+	ulong regs[4];
+
+	if(strcmp(m->cpuidid, "AuthenticAMD") == 0){
+		cpuid(0x80000007, regs);
+		return (regs[3] & (1 << 7)) != 0;
+	}
+	return 0;
+}
+
+static void
+amdpstateset(ulong pst)
+{
+	vlong cmdmsr;
+	long i;
+	Mach *w;
+
+	w = up->wired;
+	cmdmsr = pst & 15;
+	for(i = 0; i < conf.nmach; ++i){
+		procwired(up, i);
+		sched();
+		if(wrmsr(0xC0010062, cmdmsr) < 0)
+			print("error setting P-state %uld on mach %ld\n", pst, i);
+	}
+	up->wired = w;
+	sched();
+}
+
+static void
+amdpstatectl(Cmdbuf *cb)
+{
+	Cmdtab *ct;
+	vlong limmsr;
+	ulong PstateMaxVal;
+
+	ct = lookupcmd(cb, amdpstatectlmsg, nelem(amdpstatectlmsg));
+	switch(ct->index){
+	case CMpowersave:
+		if(rdmsr(0xC0010061, &limmsr) < 0){
+			cmderror(cb, "MSRC001_0061 unsupported?!");
+			return;
+		}
+		PstateMaxVal = (limmsr >> 4) & 15;
+		print("PStateMaxVal: %uld\n", PstateMaxVal);
+
+		amdpstateset(PstateMaxVal);
+
+		return;
+	}
+
+	cmderror(cb, "bad cpufreq control message");
+}
+
+static long
+amdpstatectlwrite(Chan *c, void *a, long n, vlong off)
+{
+	Cmdbuf *cb;
+
+	if(off || n >= READSTR)
+		error(Ebadarg);
+
+	cb = parsecmd(a, n);
+	if(waserror()){
+		free(cb);
+		nexterror();
+	}
+	amdpstatectl(cb);
+	poperror();
+	free(cb);
+	return n;
+}
+
+void
+cpufreqlink(void)
+{
+	if(amdpstatecpufreqok())
+		addarchfile("cpufreqctl", 0664, nil, amdpstatectlwrite);
+}
diff --git a/sys/src/9/pc/pc b/sys/src/9/pc/pc
--- a/sys/src/9/pc/pc
+++ b/sys/src/9/pc/pc
@@ -48,6 +48,7 @@
 	devpccard
 	devi82365
 	cputemp
+	cpufreq
 	apm		apmjump
 	ether2000	ether8390
 	ether2114x	pci
diff --git a/sys/src/9/pc64/pc64 b/sys/src/9/pc64/pc64
--- a/sys/src/9/pc64/pc64
+++ b/sys/src/9/pc64/pc64
@@ -47,6 +47,7 @@
 #	devpccard
 #	devi82365
 	cputemp
+	cpufreq
 #	ether2000	ether8390
 #	ether2114x	pci
 #	ether589	etherelnk3