Index: usr.sbin/powerd/powerd.8
diff -u usr.sbin/powerd/powerd.8.orig usr.sbin/powerd/powerd.8
--- usr.sbin/powerd/powerd.8.orig	Fri Jun 17 05:01:43 2005
+++ usr.sbin/powerd/powerd.8	Tue Jun 21 03:55:55 2005
@@ -34,10 +34,12 @@
 .Nm
 .Op Fl a Ar mode
 .Op Fl b Ar mode
+.Op Fl c Ar ival
 .Op Fl i Ar percent
 .Op Fl n Ar mode
 .Op Fl p Ar ival
 .Op Fl r Ar percent
+.Op Fl t
 .Op Fl v
 .Sh DESCRIPTION
 The
@@ -69,6 +71,9 @@
 Selects the
 .Ar mode
 to use while on battery power.
+.It Fl c Ar ival
+Specifies a different polling interval (in milliseconds) for cooling down.
+The default is 10000 ms.
 .It Fl i Ar percent
 Specifies the CPU idle percent level when
 adaptive
@@ -87,6 +92,10 @@
 adaptive
 mode should consider the CPU running and increase performance.
 The default is 65% or lower.
+.It Fl t
+When the temperature is too high, the
+.Nm
+decrease the frequency for cooling down.
 .It Fl v
 Verbose mode.
 Messages about power changes will be printed to stdout and
Index: usr.sbin/powerd/powerd.c
diff -u -p usr.sbin/powerd/powerd.c.orig usr.sbin/powerd/powerd.c
--- usr.sbin/powerd/powerd.c.orig	Mon Apr 11 05:42:55 2005
+++ usr.sbin/powerd/powerd.c	Tue Jun 21 05:32:58 2005
@@ -47,6 +47,7 @@ __FBSDID("$FreeBSD: src/usr.sbin/powerd/
 #define DEFAULT_ACTIVE_PERCENT	65
 #define DEFAULT_IDLE_PERCENT	90
 #define DEFAULT_POLL_INTERVAL	500	/* Poll interval in milliseconds */
+#define DEFAULT_COOL_INTERVAL	10000
 
 enum modes_t {
 	MODE_MIN,
@@ -83,11 +84,14 @@ static int	cp_time_mib[2];
 static int	freq_mib[4];
 static int	levels_mib[4];
 static int	acline_mib[3];
+static int	thermal_mib[5];
+static int	temperature_mib[5];
 
 /* Configuration */
 static int	cpu_running_mark;
 static int	cpu_idle_mark;
 static int	poll_ival;
+static int	cool_ival;
 
 static int	apm_fd;
 static int	exit_requested;
@@ -219,6 +223,53 @@ acline_read()
 	return (acline);
 }
 
+static int
+cooling_down(int curfreq, int *freqs, int numfreqs, int vflag)
+{
+	static int temperature = 0;		/* in kelvin */
+	static int count = 0;
+	int thermal_flags, curtemp, len, i = -1;
+
+	len = sizeof(thermal_flags);
+	if (sysctl(thermal_mib, 5, &thermal_flags, &len, NULL, 0) ||
+	    !thermal_flags) {
+		temperature = 0;
+		count = 0;
+		return (0);
+	}
+	if (count > 0) {
+		count--;
+		return (1);
+	}
+	count = cool_ival / poll_ival;
+	len = sizeof(curtemp);
+	if (sysctl(temperature_mib, 5, &curtemp, &len, NULL, 0)) {
+		/* Switch to the lowest frequency for safety. */
+		i = numfreqs - 1;
+		temperature = 0;
+	} else if (curtemp >= temperature) {
+		for (i = 0; i < numfreqs - 1; i++)
+			if (freqs[i] <= curfreq)
+				break;
+		if (i < numfreqs - 1)
+			i++;
+		temperature = curtemp;
+	}
+	if (i < 0)
+		return (1);	/* Goes well, we don't need to do. */
+	if (curfreq == freqs[i])
+		return (1);	/* We can nothing to do. */
+	if (vflag) {
+		printf("temperature %d.%dC; "
+		    "decreasing clock speed from %d MHz to %d MHz\n",
+		    (temperature - 2732) / 10, (temperature - 2732) % 10,
+		    curfreq, freqs[i]);
+	}
+	if (set_freq(freqs[i]))
+		err(1, "error setting CPU freq %d", freqs[i]);
+	return (1);
+}
+
 static void
 parse_mode(char *arg, int *mode, int ch)
 {
@@ -244,7 +295,8 @@ usage(void)
 {
 
 	fprintf(stderr,
-"usage: powerd [-v] [-a mode] [-b mode] [-i %%] [-n mode] [-p ival] [-r %%]\n");
+"usage: powerd [-v] [-a mode] [-b mode] [-i %%] [-n mode] [-p ival] [-r %%]\n"
+"              [-t] [-c ival]\n");
 	exit(1);
 }
 
@@ -253,7 +305,7 @@ main(int argc, char * argv[])
 {
 	long idle, total;
 	int curfreq, *freqs, i, *mwatts, numfreqs;
-	int ch, mode_ac, mode_battery, mode_none, acline, mode, vflag;
+	int ch, mode_ac, mode_battery, mode_none, acline, mode, tflag, vflag;
 	uint64_t mjoules_used;
 	size_t len;
 
@@ -262,11 +314,13 @@ main(int argc, char * argv[])
 	cpu_running_mark = DEFAULT_ACTIVE_PERCENT;
 	cpu_idle_mark = DEFAULT_IDLE_PERCENT;
 	poll_ival = DEFAULT_POLL_INTERVAL;
+	cool_ival = DEFAULT_COOL_INTERVAL;
 	mjoules_used = 0;
+	tflag = 0;
 	vflag = 0;
 	apm_fd = -1;
 
-	while ((ch = getopt(argc, argv, "a:b:i:n:p:r:v")) != EOF)
+	while ((ch = getopt(argc, argv, "a:b:c:i:n:p:r:tv")) != EOF)
 		switch (ch) {
 		case 'a':
 			parse_mode(optarg, &mode_ac, ch);
@@ -274,6 +328,13 @@ main(int argc, char * argv[])
 		case 'b':
 			parse_mode(optarg, &mode_battery, ch);
 			break;
+		case 'c':
+			cool_ival = atoi(optarg);
+			if (cool_ival < 0) {
+				warnx("cooling interval is in units of ms");
+				usage();
+			}
+			break;
 		case 'i':
 			cpu_idle_mark = atoi(optarg);
 			if (cpu_idle_mark < 0 || cpu_idle_mark > 100) {
@@ -300,6 +361,9 @@ main(int argc, char * argv[])
 				usage();
 			}
 			break;
+		case 't':
+			tflag = 1;
+			break;
 		case 'v':
 			vflag = 1;
 			break;
@@ -309,6 +373,7 @@ main(int argc, char * argv[])
 
 	/* Poll interval is in units of ms. */
 	poll_ival *= 1000;
+	cool_ival *= 1000;
 
 	/* Look up various sysctl MIBs. */
 	len = 2;
@@ -320,6 +385,16 @@ main(int argc, char * argv[])
 	len = 4;
 	if (sysctlnametomib("dev.cpu.0.freq_levels", levels_mib, &len))
 		err(1, "lookup freq_levels");
+	if (tflag) {
+		len = 5;
+		if (sysctlnametomib("hw.acpi.thermal.tz0.thermal_flags",
+		    thermal_mib, &len))
+			err(1, "lookup thermal_flags");
+		len = 5;
+		if (sysctlnametomib("hw.acpi.thermal.tz0.temperature",
+		    temperature_mib, &len))
+			err(1, "lookup temperature");
+	}
 
 	/* Check if we can read the idle time and supported freqs. */
 	if (read_usage_times(NULL, NULL))
@@ -382,6 +457,9 @@ main(int argc, char * argv[])
 				mjoules_used +=
 				    (mwatts[i] * (poll_ival / 1000)) / 1000;
 		}
+
+		if (tflag && cooling_down(curfreq, freqs, numfreqs, vflag))
+			continue;
 
 		/* Always switch to the lowest frequency in min mode. */
 		if (mode == MODE_MIN) {