PowerOP 3/3: Intel Centrino cpufreq integration

PowerOP 3/3: Intel Centrino cpufreq integration

[Todd Poynor]

A minimal example of modifying cpufreq to use PowerOP for reading and
writing power parameters on Intel Centrino platforms.  It would be
possible to move voltage table lookups to the PowerOP layer.


Index: linux-2.6.12/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
===================================================================
--- linux-2.6.12.orig/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c	2005-08-04 19:49:29.000000000 +0000
+++ linux-2.6.12/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c	2005-08-05 01:21:45.000000000 +0000
@@ -24,6 +24,7 @@
 #include <linux/config.h>
 #include <linux/delay.h>
 #include <linux/compiler.h>
+#include <linux/powerop.h>
 
 #ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI
 #include <linux/acpi.h>
@@ -322,29 +323,21 @@
 /* Return the current CPU frequency in kHz */
 static unsigned int get_cur_freq(unsigned int cpu)
 {
-	unsigned l, h;
-	unsigned clock_freq;
+	struct powerop_point point;
+	unsigned clock_freq = 0;
 	cpumask_t saved_mask;
	
 	saved_mask = current->cpus_allowed;
 	set_cpus_allowed(current, cpumask_of_cpu(cpu));
 	if (smp_processor_id() != cpu)
 		return 0;
 
-	rdmsr(MSR_IA32_PERF_STATUS, l, h);
-	clock_freq = extract_clock(l, cpu, 0);
+	if (powerop_get_point(&point))
+		goto out;
 
-	if (unlikely(clock_freq == 0)) {
-		/*
-		 * On some CPUs, we can see transient MSR values (which are
-		 * not present in _PSS), while CPU is doing some automatic
-		 * P-state transition (like TM2). Get the last freq set 
-		 * in PERF_CTL.
-		 */
-		rdmsr(MSR_IA32_PERF_CTL, l, h);
-		clock_freq = extract_clock(l, cpu, 1);
-	}
+	clock_freq = point.param[POWEROP_CPU + cpu] * 1000;
 
+out:
 	set_cpus_allowed(current, saved_mask);
 	return clock_freq;
 }
@@ -610,6 +603,7 @@
 	unsigned int	msr, oldmsr, h, cpu = policy->cpu;
 	struct cpufreq_freqs	freqs;
 	cpumask_t		saved_mask;
+	struct powerop_point	point;
 	int			retval;
 
 	if (centrino_model[cpu] == NULL)
@@ -650,14 +644,9 @@
 
 	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 
-	/* all but 16 LSB are "reserved", so treat them with
-	   care */
-	oldmsr &= ~0xffff;
-	msr &= 0xffff;
-	oldmsr |= msr;
-
-	wrmsr(MSR_IA32_PERF_CTL, oldmsr, h);
-
+	point.param[POWEROP_CPU + cpu] = ((msr >> 8) & 0xff) * 100;
+	point.param[POWEROP_V + cpu] = ((msr & 0xff) * 16) + 700;
+	powerop_set_point(&point);
 	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 
 	retval = 0;

Re: PowerOP 3/3: Intel Centrino cpufreq integration

[Pavel Machek]

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Hi!

> A minimal example of modifying cpufreq to use PowerOP for reading and
> writing power parameters on Intel Centrino platforms.  It would be
> possible to move voltage table lookups to the PowerOP layer.

Aha, ok, sorry for my previous comment. It looks like powerop
framework can cleanup speedstep-centrino a tiny bit. Where else is it
used?

								Pavel

-- 
if you have sharp zaurus hardware you don't need... you know my address

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