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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>
This commit is contained in:
Andre Przywara 2012-09-04 08:28:08 +00:00 committed by Rafael J. Wysocki
parent 615b730071
commit 11269ff506
2 changed files with 56 additions and 2 deletions
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12
drivers/cpufreq/Kconfig.x86
View File

@ -33,6 +33,18 @@ config X86_ACPI_CPUFREQ
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

46
drivers/cpufreq/acpi-cpufreq.c
View File

@ -133,8 +133,7 @@ static void boost_set_msrs(bool enable, const struct cpumask *cpumask)
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 @@ static ssize_t store_global_boost(struct kobject *kobj, struct attribute *attr,
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 @@ static struct global_attr global_boost = __ATTR(boost, 0644,
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 int acpi_cpufreq_resume(struct cpufreq_policy *policy)
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 @@ static int __init acpi_cpufreq_init(void)
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();