[PATCH] e_powersaver: Check BIOS limit for CPU frequency

From: RafaÅ Bilski
Date: Thu Jul 21 2011 - 17:08:50 EST


Call ACPI function to get BIOS limit for CPU frequency.
Fail if processor would like to run at higher frequency.
Allow user to ignore BIOS limit.

eps: Detected VIA Model D C7-M
eps: Current voltage = 1084mV
eps: Current multiplier = 16
eps: Highest voltage = 1084mV
eps: Highest multiplier = 16
eps: Lowest voltage = 844mV
eps: Lowest multiplier = 4
eps: ACPI limit 1.60GHz

Signed-off-by: RafaÅ Bilski <rafalbilski@xxxxxxxxxx>
---
drivers/cpufreq/e_powersaver.c | 76 ++++++++++++++++++++++++++++++++++++++++
1 files changed, 76 insertions(+), 0 deletions(-)

diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
index cab543b..7638f5d 100644
--- a/drivers/cpufreq/e_powersaver.c
+++ b/drivers/cpufreq/e_powersaver.c
@@ -19,6 +19,11 @@
#include <asm/msr.h>
#include <asm/tsc.h>

+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+#include <linux/acpi.h>
+#include <acpi/processor.h>
+#endif
+
#define EPS_BRAND_C7M 0
#define EPS_BRAND_C7 1
#define EPS_BRAND_EDEN 2
@@ -27,6 +32,9 @@

struct eps_cpu_data {
u32 fsb;
+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+ u32 bios_limit;
+#endif
struct cpufreq_frequency_table freq_table[];
};

@@ -36,6 +44,46 @@ static struct eps_cpu_data *eps_cpu[NR_CPUS];
static int freq_failsafe_off;
static int voltage_failsafe_off;

+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+static int ignore_acpi_limit;
+
+static struct acpi_processor_performance *eps_acpi_cpu_perf;
+
+/* Minimum necessary to get acpi_processor_get_bios_limit() working */
+static int eps_acpi_init(void)
+{
+ eps_acpi_cpu_perf = kzalloc(sizeof(struct acpi_processor_performance),
+ GFP_KERNEL);
+ if (!eps_acpi_cpu_perf)
+ return -ENOMEM;
+
+ if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
+ GFP_KERNEL)) {
+ kfree(eps_acpi_cpu_perf);
+ eps_acpi_cpu_perf = NULL;
+ return -ENOMEM;
+ }
+
+ if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
+ free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
+ kfree(eps_acpi_cpu_perf);
+ eps_acpi_cpu_perf = NULL;
+ return -EIO;
+ }
+ return 0;
+}
+
+static int eps_acpi_exit(struct cpufreq_policy *policy)
+{
+ if (eps_acpi_cpu_perf) {
+ acpi_processor_unregister_performance(eps_acpi_cpu_perf, 0);
+ free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
+ kfree(eps_acpi_cpu_perf);
+ eps_acpi_cpu_perf = NULL;
+ }
+ return 0;
+}
+#endif

static unsigned int eps_get(unsigned int cpu)
{
@@ -168,6 +216,9 @@ static int eps_cpu_init(struct cpufreq_policy *policy)
int k, step, voltage;
int ret;
int states;
+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+ unsigned int limit;
+#endif

if (policy->cpu != 0)
return -ENODEV;
@@ -280,6 +331,24 @@ static int eps_cpu_init(struct cpufreq_policy *policy)

/* Calc FSB speed */
fsb = cpu_khz / current_multiplier;
+
+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+ /* Check for ACPI processor speed limit */
+ if (!ignore_acpi_limit && !eps_acpi_init()) {
+ if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
+ printk(KERN_INFO "eps: ACPI limit %u.%uGHz\n",
+ limit/1000000,
+ (limit%1000000)/10000);
+ eps_acpi_exit(policy);
+ /* Check if max_multiplier is in BIOS limits */
+ if (limit && max_multiplier * fsb > limit) {
+ printk(KERN_INFO "eps: Aborting.\n");
+ return -EINVAL;
+ }
+ }
+ }
+#endif
+
/* Calc number of p-states supported */
if (brand == EPS_BRAND_C7M)
states = max_multiplier - min_multiplier + 1;
@@ -296,6 +365,9 @@ static int eps_cpu_init(struct cpufreq_policy *policy)

/* Copy basic values */
centaur->fsb = fsb;
+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+ centaur->bios_limit = limit;
+#endif

/* Fill frequency and MSR value table */
f_table = &centaur->freq_table[0];
@@ -386,6 +458,10 @@ module_param(freq_failsafe_off, int, 0644);
MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
module_param(voltage_failsafe_off, int, 0644);
MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
+#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
+module_param(ignore_acpi_limit, int, 0644);
+MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
+#endif

MODULE_AUTHOR("Rafal Bilski <rafalbilski@xxxxxxxxxx>");
MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
--
1.7.6


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