Set levels on all CPUs and attach a cpufreq device to each one. Sysctl

on dev.cpu.0 will affect all of the CPUs together.  In the future,
independent control will be supported but this is good enough for now.
Check that the timecounter isn't TSC before switching (from Colin Percival.)

1 files changed, 62 insertions, 22 deletions

diff --git a/sys/kern/kern_cpu.c b/sys/kern/kern_cpu.c
index 67345a5a7015..c058ead38d4b 100644
--- a/sys/kern/kern_cpu.c
+++ b/sys/kern/kern_cpu.c
@@ -40,6 +40,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 #include <sys/systm.h>
 #include <sys/sbuf.h>
+#include <sys/timetc.h>
 
 #include "cpufreq_if.h"
 
@@ -171,14 +172,33 @@ cf_set_method(device_t dev, const struct cf_level *level, int priority)
 {
 	struct cpufreq_softc *sc;
 	const struct cf_setting *set;
-	int error, i;
+	struct pcpu *pc;
+	int cpu_id, error, i;
 
 	sc = device_get_softc(dev);
 
+	/*
+	 * Check that the TSC isn't being used as a timecounter.
+	 * If it is, then return EBUSY and refuse to change the
+	 * clock speed.
+	 */
+	if (strcmp(timecounter->tc_name, "TSC") == 0)
+		return (EBUSY);
+
 	/* If already at this level, just return. */
 	if (CPUFREQ_CMP(sc->curr_level.total_set.freq, level->total_set.freq))
 		return (0);
 
+	/* If the setting is for a different CPU, switch to it. */
+	cpu_id = PCPU_GET(cpuid);
+	pc = cpu_get_pcpu(dev);
+	KASSERT(pc, ("NULL pcpu for dev %p", dev));
+	if (cpu_id != pc->pc_cpuid) {
+		mtx_lock_spin(&sched_lock);
+		sched_bind(curthread, pc->pc_cpuid);
+		mtx_unlock_spin(&sched_lock);
+	}
+
 	/* First, set the absolute frequency via its driver. */
 	set = &level->abs_set;
 	if (set->dev) {
@@ -212,6 +232,12 @@ cf_set_method(device_t dev, const struct cf_level *level, int priority)
 	error = 0;
 
 out:
+	/* If we switched to another CPU, switch back before exiting. */
+	if (cpu_id != pc->pc_cpuid) {
+		mtx_lock_spin(&sched_lock);
+		sched_unbind(curthread);
+		mtx_unlock_spin(&sched_lock);
+	}
 	if (error)
 		device_printf(set->dev, "set freq failed, err %d\n", error);
 	return (error);
@@ -329,7 +355,7 @@ cf_levels_method(device_t dev, struct cf_level *levels, int *count)
 		if (error || set_count == 0)
 			continue;
 
-		switch (type) {
+		switch (type & CPUFREQ_TYPE_MASK) {
 		case CPUFREQ_TYPE_ABSOLUTE:
 			error = cpufreq_insert_abs(sc, sets, set_count);
 			break;
@@ -567,11 +593,12 @@ cpufreq_curr_sysctl(SYSCTL_HANDLER_ARGS)
 {
 	struct cpufreq_softc *sc;
 	struct cf_level *levels;
-	int count, error, freq, i;
+	int count, devcount, error, freq, i, n;
+	device_t *devs;
 
+	devs = NULL;
 	sc = oidp->oid_arg1;
-	count = CF_MAX_LEVELS;
-	levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
+	levels = malloc(CF_MAX_LEVELS * sizeof(*levels), M_TEMP, M_NOWAIT);
 	if (levels == NULL)
 		return (ENOMEM);
 
@@ -583,20 +610,35 @@ cpufreq_curr_sysctl(SYSCTL_HANDLER_ARGS)
 	if (error != 0 || req->newptr == NULL)
 		goto out;
 
-	error = CPUFREQ_LEVELS(sc->dev, levels, &count);
+	/*
+	 * While we only call cpufreq_get() on one device (assuming all
+	 * CPUs have equal levels), we call cpufreq_set() on all CPUs.
+	 * This is needed for some MP systems.
+	 */
+	error = devclass_get_devices(cpufreq_dc, &devs, &devcount);
 	if (error)
 		goto out;
-	for (i = 0; i < count; i++) {
-		if (CPUFREQ_CMP(levels[i].total_set.freq, freq)) {
-			error = CPUFREQ_SET(sc->dev, &levels[i],
-			    CPUFREQ_PRIO_USER);
+	for (n = 0; n < devcount; n++) {
+		count = CF_MAX_LEVELS;
+		error = CPUFREQ_LEVELS(devs[n], levels, &count);
+		if (error)
+			break;
+		for (i = 0; i < count; i++) {
+			if (CPUFREQ_CMP(levels[i].total_set.freq, freq)) {
+				error = CPUFREQ_SET(devs[n], &levels[i],
+				    CPUFREQ_PRIO_USER);
+				break;
+			}
+		}
+		if (i == count) {
+			error = EINVAL;
 			break;
 		}
 	}
-	if (i == count)
-		error = EINVAL;
 
 out:
+	if (devs)
+		free(devs, M_TEMP);
 	if (levels)
 		free(levels, M_TEMP);
 	return (error);
@@ -645,17 +687,16 @@ cpufreq_register(device_t dev)
 	device_t cf_dev, cpu_dev;
 
 	/*
-	 * Only add one cpufreq device (on cpu0) for all control.  Once
-	 * independent multi-cpu control appears, we can assign one cpufreq
-	 * device per cpu.
+	 * Add only one cpufreq device to each CPU.  Currently, all CPUs
+	 * must offer the same levels and be switched at the same time.
 	 */
-	cf_dev = devclass_get_device(cpufreq_dc, 0);
-	if (cf_dev)
+	cpu_dev = device_get_parent(dev);
+	KASSERT(cpu_dev != NULL, ("no parent for %p", dev));
+	if (device_find_child(cpu_dev, "cpufreq", -1))
 		return (0);
 
-	/* Add the child device and sysctls. */
-	cpu_dev = devclass_get_device(devclass_find("cpu"), 0);
-	cf_dev = BUS_ADD_CHILD(cpu_dev, 0, "cpufreq", 0);
+	/* Add the child device and possibly sysctls. */
+	cf_dev = BUS_ADD_CHILD(cpu_dev, 0, "cpufreq", -1);
 	if (cf_dev == NULL)
 		return (ENOMEM);
 	device_quiet(cf_dev);
@@ -688,9 +729,8 @@ cpufreq_unregister(device_t dev)
 		if (CPUFREQ_DRV_SETTINGS(devs[i], &set, &count, &type) == 0)
 			cfcount++;
 	}
-	if (cfcount <= 1) {
+	if (cfcount <= 1)
 		device_delete_child(device_get_parent(cf_dev), cf_dev);
-	}
 	free(devs, M_TEMP);
 
 	return (0);