diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt
index 2a5b850847c024e676395320f534c1982c8ae33a..04f6b32993e69ca4185a81bbaadb677aac5056e9 100644
--- a/Documentation/cpu-freq/user-guide.txt
+++ b/Documentation/cpu-freq/user-guide.txt
@@ -203,6 +203,17 @@ scaling_cur_freq : Current frequency of the CPU as determined by
the frequency the kernel thinks the CPU runs
at.
+bios_limit : If the BIOS tells the OS to limit a CPU to
+ lower frequencies, the user can read out the
+ maximum available frequency from this file.
+ This typically can happen through (often not
+ intended) BIOS settings, restrictions
+ triggered through a service processor or other
+ BIOS/HW based implementations.
+ This does not cover thermal ACPI limitations
+ which can be detected through the generic
+ thermal driver.
+
If you have selected the "userspace" governor which allows you to
set the CPU operating frequency to a specific value, you can read out
the current frequency in
diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index 8b581d3905cb47214af854582e24a379fac444f3..d2e7c77c1ea4901a8e3e6b2a70c99b5c991132f3 100644
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -764,14 +764,15 @@ static struct freq_attr *acpi_cpufreq_attr[] = {
};
static struct cpufreq_driver acpi_cpufreq_driver = {
- .verify = acpi_cpufreq_verify,
- .target = acpi_cpufreq_target,
- .init = acpi_cpufreq_cpu_init,
- .exit = acpi_cpufreq_cpu_exit,
- .resume = acpi_cpufreq_resume,
- .name = "acpi-cpufreq",
- .owner = THIS_MODULE,
- .attr = acpi_cpufreq_attr,
+ .verify = acpi_cpufreq_verify,
+ .target = acpi_cpufreq_target,
+ .bios_limit = acpi_processor_get_bios_limit,
+ .init = acpi_cpufreq_cpu_init,
+ .exit = acpi_cpufreq_cpu_exit,
+ .resume = acpi_cpufreq_resume,
+ .name = "acpi-cpufreq",
+ .owner = THIS_MODULE,
+ .attr = acpi_cpufreq_attr,
};
static int __init acpi_cpufreq_init(void)
diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k7.c b/arch/x86/kernel/cpu/cpufreq/powernow-k7.c
index d47c775eb0abce217593a99cd06dba2f87125977..9a97116f89e5ebc4805db1c608c5e79e96d847f5 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k7.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k7.c
@@ -714,14 +714,17 @@ static struct freq_attr *powernow_table_attr[] = {
};
static struct cpufreq_driver powernow_driver = {
- .verify = powernow_verify,
- .target = powernow_target,
- .get = powernow_get,
- .init = powernow_cpu_init,
- .exit = powernow_cpu_exit,
- .name = "powernow-k7",
- .owner = THIS_MODULE,
- .attr = powernow_table_attr,
+ .verify = powernow_verify,
+ .target = powernow_target,
+ .get = powernow_get,
+#ifdef CONFIG_X86_POWERNOW_K7_ACPI
+ .bios_limit = acpi_processor_get_bios_limit,
+#endif
+ .init = powernow_cpu_init,
+ .exit = powernow_cpu_exit,
+ .name = "powernow-k7",
+ .owner = THIS_MODULE,
+ .attr = powernow_table_attr,
};
static int __init powernow_init(void)
diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
index f30d25383940db77458fb41f047e43896eaa75a6..a9df9441a9a240cd138b6492896cc0788a04cf1b 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
@@ -1398,14 +1398,15 @@ static struct freq_attr *powernow_k8_attr[] = {
};
static struct cpufreq_driver cpufreq_amd64_driver = {
- .verify = powernowk8_verify,
- .target = powernowk8_target,
- .init = powernowk8_cpu_init,
- .exit = __devexit_p(powernowk8_cpu_exit),
- .get = powernowk8_get,
- .name = "powernow-k8",
- .owner = THIS_MODULE,
- .attr = powernow_k8_attr,
+ .verify = powernowk8_verify,
+ .target = powernowk8_target,
+ .bios_limit = acpi_processor_get_bios_limit,
+ .init = powernowk8_cpu_init,
+ .exit = __devexit_p(powernowk8_cpu_exit),
+ .get = powernowk8_get,
+ .name = "powernow-k8",
+ .owner = THIS_MODULE,
+ .attr = powernow_k8_attr,
};
/* driver entry point for init */
diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 8ba0ed0b9ddbc912684d398e2eda14357920aed4..01e366d2b6fb14475e0b6074b886fd8b55877348 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -167,6 +167,19 @@ int acpi_processor_ppc_has_changed(struct acpi_processor *pr)
return cpufreq_update_policy(pr->id);
}
+int acpi_processor_get_bios_limit(int cpu, unsigned int *limit)
+{
+ struct acpi_processor *pr;
+
+ pr = per_cpu(processors, cpu);
+ if (!pr || !pr->performance || !pr->performance->state_count)
+ return -ENODEV;
+ *limit = pr->performance->states[pr->performance_platform_limit].
+ core_frequency * 1000;
+ return 0;
+}
+EXPORT_SYMBOL(acpi_processor_get_bios_limit);
+
void acpi_processor_ppc_init(void)
{
if (!cpufreq_register_notifier
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 5b9b1c8c495000f5c8c071aac1e4a76d83728952..f20668c09ce0611d3da1fa8582514ccfec949347 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -647,6 +647,21 @@ static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
return policy->governor->show_setspeed(policy, buf);
}
+/**
+ * show_scaling_driver - show the current cpufreq HW/BIOS limitation
+ */
+static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
+{
+ unsigned int limit;
+ int ret;
+ if (cpufreq_driver->bios_limit) {
+ ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
+ if (!ret)
+ return sprintf(buf, "%u\n", limit);
+ }
+ return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
+}
+
#define define_one_ro(_name) \
static struct freq_attr _name = \
__ATTR(_name, 0444, show_##_name, NULL)
@@ -666,6 +681,7 @@ define_one_ro(cpuinfo_transition_latency);
define_one_ro(scaling_available_governors);
define_one_ro(scaling_driver);
define_one_ro(scaling_cur_freq);
+define_one_ro(bios_limit);
define_one_ro(related_cpus);
define_one_ro(affected_cpus);
define_one_rw(scaling_min_freq);
@@ -905,6 +921,11 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
if (ret)
goto err_out_kobj_put;
}
+ if (cpufreq_driver->bios_limit) {
+ ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
+ if (ret)
+ goto err_out_kobj_put;
+ }
spin_lock_irqsave(&cpufreq_driver_lock, flags);
for_each_cpu(j, policy->cpus) {
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 740ac3ad8fd06fc61b8e2dacc10054ec27469439..8b668ead6d6e84a55f7cd9c743524cbeace28e1a 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -295,6 +295,7 @@ static inline void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx
void acpi_processor_ppc_init(void);
void acpi_processor_ppc_exit(void);
int acpi_processor_ppc_has_changed(struct acpi_processor *pr);
+extern int acpi_processor_get_bios_limit(int cpu, unsigned int *limit);
#else
static inline void acpi_processor_ppc_init(void)
{
@@ -316,6 +317,11 @@ static inline int acpi_processor_ppc_has_changed(struct acpi_processor *pr)
}
return 0;
}
+static inline int acpi_processor_get_bios_limit(int cpu, unsigned int *limit)
+{
+ return -ENODEV;
+}
+
#endif /* CONFIG_CPU_FREQ */
/* in processor_throttling.c */
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 79a2340d83cda45c88138841fe4b2a8a3892bcad..4de02b10007ff4258ce6be681687d263239e1c12 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -232,6 +232,7 @@ struct cpufreq_driver {
/* optional */
unsigned int (*getavg) (struct cpufreq_policy *policy,
unsigned int cpu);
+ int (*bios_limit) (int cpu, unsigned int *limit);
int (*exit) (struct cpufreq_policy *policy);
int (*suspend) (struct cpufreq_policy *policy, pm_message_t pmsg);