Add support for the CPUFREQ_FLAG_INFO_ONLY flag. Devices that report this

are not added to the list(s) of available settings.  However, other drivers
can call the CPUFREQ_DRV_SETTINGS() method on those devices directly to
get info about available settings.

Update the acpi_perf(4) driver to use this flag in the presence of
"functional fixed hardware."  Thus, future drivers like Powernow can
query acpi_perf for platform info but perform frequency transitions
themselves.

1 files changed, 8 insertions, 1 deletions

diff --git a/sys/kern/kern_cpu.c b/sys/kern/kern_cpu.c
index c058ead..ff1d006 100644
--- a/sys/kern/kern_cpu.c
+++ b/sys/kern/kern_cpu.c
@@ -348,13 +348,20 @@ cf_levels_method(device_t dev, struct cf_level *levels, int *count)
 
 	/* Get settings from all cpufreq drivers. */
 	for (i = 0; i < numdevs; i++) {
+		/* Skip devices that aren't ready. */
 		if (!device_is_attached(devs[i]))
 			continue;
+
+		/*
+		 * Get settings, skipping drivers that offer no settings or
+		 * provide settings for informational purposes only.
+		 */
 		set_count = MAX_SETTINGS;
 		error = CPUFREQ_DRV_SETTINGS(devs[i], sets, &set_count, &type);
-		if (error || set_count == 0)
+		if (error || set_count == 0 || (type & CPUFREQ_FLAG_INFO_ONLY))
 			continue;
 
+		/* Add the settings to our absolute/relative lists. */
 		switch (type & CPUFREQ_TYPE_MASK) {
 		case CPUFREQ_TYPE_ABSOLUTE:
 			error = cpufreq_insert_abs(sc, sets, set_count);