acpi-cpufreq: Add compatibility for legacy AMD cpb sysfs knob
The powernow-k8 driver supported a sysfs knob called "cpb", which was
instantiated per CPU, but actually acted globally for the whole
system. To keep some compatibility with this feature, we re-introduce
this behavior here, but:
a) only enable it on AMD CPUs and
b) protect it with a Kconfig switch
I'd like to consider this feature obsolete. Lets keep it around for
some kernel versions and then phase it out.
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
index b36ca1f..934854a 100644
--- a/drivers/cpufreq/Kconfig.x86
+++ b/drivers/cpufreq/Kconfig.x86
@@ -33,6 +33,18 @@
If in doubt, say N.
+config X86_ACPI_CPUFREQ_CPB
+ default y
+ bool "Legacy cpb sysfs knob support for AMD CPUs"
+ depends on X86_ACPI_CPUFREQ && CPU_SUP_AMD
+ help
+ The powernow-k8 driver used to provide a sysfs knob called "cpb"
+ to disable the Core Performance Boosting feature of AMD CPUs. This
+ file has now been superseeded by the more generic "boost" entry.
+
+ By enabling this option the acpi_cpufreq driver provides the old
+ entry in addition to the new boost ones, for compatibility reasons.
+
config ELAN_CPUFREQ
tristate "AMD Elan SC400 and SC410"
select CPU_FREQ_TABLE
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index dffa7af..0d048f6 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -133,8 +133,7 @@
wrmsr_on_cpus(cpumask, msr_addr, msrs);
}
-static ssize_t store_global_boost(struct kobject *kobj, struct attribute *attr,
- const char *buf, size_t count)
+static ssize_t _store_boost(const char *buf, size_t count)
{
int ret;
unsigned long val = 0;
@@ -161,6 +160,12 @@
return count;
}
+static ssize_t store_global_boost(struct kobject *kobj, struct attribute *attr,
+ const char *buf, size_t count)
+{
+ return _store_boost(buf, count);
+}
+
static ssize_t show_global_boost(struct kobject *kobj,
struct attribute *attr, char *buf)
{
@@ -171,6 +176,21 @@
show_global_boost,
store_global_boost);
+#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
+static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
+ size_t count)
+{
+ return _store_boost(buf, count);
+}
+
+static ssize_t show_cpb(struct cpufreq_policy *policy, char *buf)
+{
+ return sprintf(buf, "%u\n", boost_enabled);
+}
+
+static struct freq_attr cpb = __ATTR(cpb, 0644, show_cpb, store_cpb);
+#endif
+
static int check_est_cpu(unsigned int cpuid)
{
struct cpuinfo_x86 *cpu = &cpu_data(cpuid);
@@ -889,6 +909,7 @@
static struct freq_attr *acpi_cpufreq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
+ NULL, /* this is a placeholder for cpb, do not remove */
NULL,
};
@@ -960,6 +981,27 @@
if (ret)
return ret;
+#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
+ /* this is a sysfs file with a strange name and an even stranger
+ * semantic - per CPU instantiation, but system global effect.
+ * Lets enable it only on AMD CPUs for compatibility reasons and
+ * only if configured. This is considered legacy code, which
+ * will probably be removed at some point in the future.
+ */
+ if (check_amd_hwpstate_cpu(0)) {
+ struct freq_attr **iter;
+
+ pr_debug("adding sysfs entry for cpb\n");
+
+ for (iter = acpi_cpufreq_attr; *iter != NULL; iter++)
+ ;
+
+ /* make sure there is a terminator behind it */
+ if (iter[1] == NULL)
+ *iter = &cpb;
+ }
+#endif
+
ret = cpufreq_register_driver(&acpi_cpufreq_driver);
if (ret)
free_acpi_perf_data();