drivers/cpufreq/longrun.c - kernel/bruno - Git at Google

 /*
  * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
  *
  *  Licensed under the terms of the GNU GPL License version 2.
  *
  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
 #include <linux/timex.h>

 #include <asm/msr.h>
 #include <asm/processor.h>
 #include <asm/cpu_device_id.h>

 static struct cpufreq_driver	longrun_driver;

 /**
  * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
  * values into per cent values. In TMTA microcode, the following is valid:
  * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
  */
 static unsigned int longrun_low_freq, longrun_high_freq;


 /**
  * longrun_get_policy - get the current LongRun policy
  * @policy: struct cpufreq_policy where current policy is written into
  *
  * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
  * and MSR_TMTA_LONGRUN_CTRL
  */
 static void longrun_get_policy(struct cpufreq_policy *policy)
 {
 	u32 msr_lo, msr_hi;

 	rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
 	pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi);
 	if (msr_lo & 0x01)
 		policy->policy = CPUFREQ_POLICY_PERFORMANCE;
 	else
 		policy->policy = CPUFREQ_POLICY_POWERSAVE;

 	rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 	pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
 	msr_lo &= 0x0000007F;
 	msr_hi &= 0x0000007F;

 	if (longrun_high_freq <= longrun_low_freq) {
 		/* Assume degenerate Longrun table */
 		policy->min = policy->max = longrun_high_freq;
 	} else {
 		policy->min = longrun_low_freq + msr_lo *
 			((longrun_high_freq - longrun_low_freq) / 100);
 		policy->max = longrun_low_freq + msr_hi *
 			((longrun_high_freq - longrun_low_freq) / 100);
 	}
 	policy->cpu = 0;
 }


 /**
  * longrun_set_policy - sets a new CPUFreq policy
  * @policy: new policy
  *
  * Sets a new CPUFreq policy on LongRun-capable processors. This function
  * has to be called with cpufreq_driver locked.
  */
 static int longrun_set_policy(struct cpufreq_policy *policy)
 {
 	u32 msr_lo, msr_hi;
 	u32 pctg_lo, pctg_hi;

 	if (!policy)
 		return -EINVAL;

 	if (longrun_high_freq <= longrun_low_freq) {
 		/* Assume degenerate Longrun table */
 		pctg_lo = pctg_hi = 100;
 	} else {
 		pctg_lo = (policy->min - longrun_low_freq) /
 			((longrun_high_freq - longrun_low_freq) / 100);
 		pctg_hi = (policy->max - longrun_low_freq) /
 			((longrun_high_freq - longrun_low_freq) / 100);
 	}

 	if (pctg_hi > 100)
 		pctg_hi = 100;
 	if (pctg_lo > pctg_hi)
 		pctg_lo = pctg_hi;

 	/* performance or economy mode */
 	rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
 	msr_lo &= 0xFFFFFFFE;
 	switch (policy->policy) {
 	case CPUFREQ_POLICY_PERFORMANCE:
 		msr_lo |= 0x00000001;
 		break;
 	case CPUFREQ_POLICY_POWERSAVE:
 		break;
 	}
 	wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);

 	/* lower and upper boundary */
 	rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 	msr_lo &= 0xFFFFFF80;
 	msr_hi &= 0xFFFFFF80;
 	msr_lo |= pctg_lo;
 	msr_hi |= pctg_hi;
 	wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);

 	return 0;
 }


 /**
  * longrun_verify_poliy - verifies a new CPUFreq policy
  * @policy: the policy to verify
  *
  * Validates a new CPUFreq policy. This function has to be called with
  * cpufreq_driver locked.
  */
 static int longrun_verify_policy(struct cpufreq_policy *policy)
 {
 	if (!policy)
 		return -EINVAL;

 	policy->cpu = 0;
 	cpufreq_verify_within_cpu_limits(policy);

 	if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
 	    (policy->policy != CPUFREQ_POLICY_PERFORMANCE))
 		return -EINVAL;

 	return 0;
 }

 static unsigned int longrun_get(unsigned int cpu)
 {
 	u32 eax, ebx, ecx, edx;

 	if (cpu)
 		return 0;

 	cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 	pr_debug("cpuid eax is %u\n", eax);

 	return eax * 1000;
 }

 /**
  * longrun_determine_freqs - determines the lowest and highest possible core frequency
  * @low_freq: an int to put the lowest frequency into
  * @high_freq: an int to put the highest frequency into
  *
  * Determines the lowest and highest possible core frequencies on this CPU.
  * This is necessary to calculate the performance percentage according to
  * TMTA rules:
  * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
  */
 static int longrun_determine_freqs(unsigned int *low_freq,
 						      unsigned int *high_freq)
 {
 	u32 msr_lo, msr_hi;
 	u32 save_lo, save_hi;
 	u32 eax, ebx, ecx, edx;
 	u32 try_hi;
 	struct cpuinfo_x86 *c = &cpu_data(0);

 	if (!low_freq || !high_freq)
 		return -EINVAL;

 	if (cpu_has(c, X86_FEATURE_LRTI)) {
 		/* if the LongRun Table Interface is present, the
 		 * detection is a bit easier:
 		 * For minimum frequency, read out the maximum
 		 * level (msr_hi), write that into "currently
 		 * selected level", and read out the frequency.
 		 * For maximum frequency, read out level zero.
 		 */
 		/* minimum */
 		rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
 		wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
 		rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
 		*low_freq = msr_lo * 1000; /* to kHz */

 		/* maximum */
 		wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
 		rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
 		*high_freq = msr_lo * 1000; /* to kHz */

 		pr_debug("longrun table interface told %u - %u kHz\n",
 				*low_freq, *high_freq);

 		if (*low_freq > *high_freq)
 			*low_freq = *high_freq;
 		return 0;
 	}

 	/* set the upper border to the value determined during TSC init */
 	*high_freq = (cpu_khz / 1000);
 	*high_freq = *high_freq * 1000;
 	pr_debug("high frequency is %u kHz\n", *high_freq);

 	/* get current borders */
 	rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
 	save_lo = msr_lo & 0x0000007F;
 	save_hi = msr_hi & 0x0000007F;

 	/* if current perf_pctg is larger than 90%, we need to decrease the
 	 * upper limit to make the calculation more accurate.
 	 */
 	cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
 	/* try decreasing in 10% steps, some processors react only
 	 * on some barrier values */
 	for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
 		/* set to 0 to try_hi perf_pctg */
 		msr_lo &= 0xFFFFFF80;
 		msr_hi &= 0xFFFFFF80;
 		msr_hi |= try_hi;
 		wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);

 		/* read out current core MHz and current perf_pctg */
 		cpuid(0x80860007, &eax, &ebx, &ecx, &edx);

 		/* restore values */
 		wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
 	}
 	pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);

 	/* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
 	 * eqals
 	 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
 	 *
 	 * high_freq * perf_pctg is stored tempoarily into "ebx".
 	 */
 	ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */

 	if ((ecx > 95) || (ecx == 0) || (eax < ebx))
 		return -EIO;

 	edx = ((eax - ebx) * 100) / (100 - ecx);
 	*low_freq = edx * 1000; /* back to kHz */

 	pr_debug("low frequency is %u kHz\n", *low_freq);

 	if (*low_freq > *high_freq)
 		*low_freq = *high_freq;

 	return 0;
 }


 static int longrun_cpu_init(struct cpufreq_policy *policy)
 {
 	int result = 0;

 	/* capability check */
 	if (policy->cpu != 0)
 		return -ENODEV;

 	/* detect low and high frequency */
 	result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
 	if (result)
 		return result;

 	/* cpuinfo and default policy values */
 	policy->cpuinfo.min_freq = longrun_low_freq;
 	policy->cpuinfo.max_freq = longrun_high_freq;
 	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 	longrun_get_policy(policy);

 	return 0;
 }


 static struct cpufreq_driver longrun_driver = {
 	.flags		= CPUFREQ_CONST_LOOPS,
 	.verify		= longrun_verify_policy,
 	.setpolicy	= longrun_set_policy,
 	.get		= longrun_get,
 	.init		= longrun_cpu_init,
 	.name		= "longrun",
 };

 static const struct x86_cpu_id longrun_ids[] = {
 	{ X86_VENDOR_TRANSMETA, X86_FAMILY_ANY, X86_MODEL_ANY,
 	  X86_FEATURE_LONGRUN },
 	{}
 };
 MODULE_DEVICE_TABLE(x86cpu, longrun_ids);

 /**
  * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
  *
  * Initializes the LongRun support.
  */
 static int __init longrun_init(void)
 {
 	if (!x86_match_cpu(longrun_ids))
 		return -ENODEV;
 	return cpufreq_register_driver(&longrun_driver);
 }


 /**
  * longrun_exit - unregisters LongRun support
  */
 static void __exit longrun_exit(void)
 {
 	cpufreq_unregister_driver(&longrun_driver);
 }


 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
 		"Efficeon processors.");
 MODULE_LICENSE("GPL");

 module_init(longrun_init);
 module_exit(longrun_exit);
	/*
	* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
	*
	* Licensed under the terms of the GNU GPL License version 2.
	*
	* BIG FAT DISCLAIMER: Work in progress code. Possibly dangerous
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/cpufreq.h>
	#include <linux/timex.h>

	#include <asm/msr.h>
	#include <asm/processor.h>
	#include <asm/cpu_device_id.h>

	static struct cpufreq_driver longrun_driver;

	/**
	* longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
	* values into per cent values. In TMTA microcode, the following is valid:
	* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
	*/
	static unsigned int longrun_low_freq, longrun_high_freq;


	/**
	* longrun_get_policy - get the current LongRun policy
	* @policy: struct cpufreq_policy where current policy is written into
	*
	* Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
	* and MSR_TMTA_LONGRUN_CTRL
	*/
	static void longrun_get_policy(struct cpufreq_policy *policy)
	{
	u32 msr_lo, msr_hi;

	rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
	pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi);
	if (msr_lo & 0x01)
	policy->policy = CPUFREQ_POLICY_PERFORMANCE;
	else
	policy->policy = CPUFREQ_POLICY_POWERSAVE;

	rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
	pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
	msr_lo &= 0x0000007F;
	msr_hi &= 0x0000007F;

	if (longrun_high_freq <= longrun_low_freq) {
	/* Assume degenerate Longrun table */
	policy->min = policy->max = longrun_high_freq;
	} else {
	policy->min = longrun_low_freq + msr_lo *
	((longrun_high_freq - longrun_low_freq) / 100);
	policy->max = longrun_low_freq + msr_hi *
	((longrun_high_freq - longrun_low_freq) / 100);
	}
	policy->cpu = 0;
	}


	/**
	* longrun_set_policy - sets a new CPUFreq policy
	* @policy: new policy
	*
	* Sets a new CPUFreq policy on LongRun-capable processors. This function
	* has to be called with cpufreq_driver locked.
	*/
	static int longrun_set_policy(struct cpufreq_policy *policy)
	{
	u32 msr_lo, msr_hi;
	u32 pctg_lo, pctg_hi;

	if (!policy)
	return -EINVAL;

	if (longrun_high_freq <= longrun_low_freq) {
	/* Assume degenerate Longrun table */
	pctg_lo = pctg_hi = 100;
	} else {
	pctg_lo = (policy->min - longrun_low_freq) /
	((longrun_high_freq - longrun_low_freq) / 100);
	pctg_hi = (policy->max - longrun_low_freq) /
	((longrun_high_freq - longrun_low_freq) / 100);
	}

	if (pctg_hi > 100)
	pctg_hi = 100;
	if (pctg_lo > pctg_hi)
	pctg_lo = pctg_hi;

	/* performance or economy mode */
	rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
	msr_lo &= 0xFFFFFFFE;
	switch (policy->policy) {
	case CPUFREQ_POLICY_PERFORMANCE:
	msr_lo \|= 0x00000001;
	break;
	case CPUFREQ_POLICY_POWERSAVE:
	break;
	}
	wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);

	/* lower and upper boundary */
	rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
	msr_lo &= 0xFFFFFF80;
	msr_hi &= 0xFFFFFF80;
	msr_lo \|= pctg_lo;
	msr_hi \|= pctg_hi;
	wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);

	return 0;
	}


	/**
	* longrun_verify_poliy - verifies a new CPUFreq policy
	* @policy: the policy to verify
	*
	* Validates a new CPUFreq policy. This function has to be called with
	* cpufreq_driver locked.
	*/
	static int longrun_verify_policy(struct cpufreq_policy *policy)
	{
	if (!policy)
	return -EINVAL;

	policy->cpu = 0;
	cpufreq_verify_within_cpu_limits(policy);

	if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
	(policy->policy != CPUFREQ_POLICY_PERFORMANCE))
	return -EINVAL;

	return 0;
	}

	static unsigned int longrun_get(unsigned int cpu)
	{
	u32 eax, ebx, ecx, edx;

	if (cpu)
	return 0;

	cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
	pr_debug("cpuid eax is %u\n", eax);

	return eax * 1000;
	}

	/**
	* longrun_determine_freqs - determines the lowest and highest possible core frequency
	* @low_freq: an int to put the lowest frequency into
	* @high_freq: an int to put the highest frequency into
	*
	* Determines the lowest and highest possible core frequencies on this CPU.
	* This is necessary to calculate the performance percentage according to
	* TMTA rules:
	* performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
	*/
	static int longrun_determine_freqs(unsigned int *low_freq,
	unsigned int *high_freq)
	{
	u32 msr_lo, msr_hi;
	u32 save_lo, save_hi;
	u32 eax, ebx, ecx, edx;
	u32 try_hi;
	struct cpuinfo_x86 *c = &cpu_data(0);

	if (!low_freq \|\| !high_freq)
	return -EINVAL;

	if (cpu_has(c, X86_FEATURE_LRTI)) {
	/* if the LongRun Table Interface is present, the
	* detection is a bit easier:
	* For minimum frequency, read out the maximum
	* level (msr_hi), write that into "currently
	* selected level", and read out the frequency.
	* For maximum frequency, read out level zero.
	*/
	/* minimum */
	rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
	wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
	rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
	low_freq = msr_lo 1000; /* to kHz */

	/* maximum */
	wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
	rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
	high_freq = msr_lo 1000; /* to kHz */

	pr_debug("longrun table interface told %u - %u kHz\n",
	low_freq, high_freq);

	if (low_freq > high_freq)
	low_freq = high_freq;
	return 0;
	}

	/* set the upper border to the value determined during TSC init */
	*high_freq = (cpu_khz / 1000);
	high_freq = high_freq * 1000;
	pr_debug("high frequency is %u kHz\n", *high_freq);

	/* get current borders */
	rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
	save_lo = msr_lo & 0x0000007F;
	save_hi = msr_hi & 0x0000007F;

	/* if current perf_pctg is larger than 90%, we need to decrease the
	* upper limit to make the calculation more accurate.
	*/
	cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
	/* try decreasing in 10% steps, some processors react only
	* on some barrier values */
	for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
	/* set to 0 to try_hi perf_pctg */
	msr_lo &= 0xFFFFFF80;
	msr_hi &= 0xFFFFFF80;
	msr_hi \|= try_hi;
	wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);

	/* read out current core MHz and current perf_pctg */
	cpuid(0x80860007, &eax, &ebx, &ecx, &edx);

	/* restore values */
	wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
	}
	pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);

	/* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
	* eqals
	* low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
	*
	* high_freq * perf_pctg is stored tempoarily into "ebx".
	*/
	ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */

	if ((ecx > 95) \|\| (ecx == 0) \|\| (eax < ebx))
	return -EIO;

	edx = ((eax - ebx) * 100) / (100 - ecx);
	low_freq = edx 1000; /* back to kHz */

	pr_debug("low frequency is %u kHz\n", *low_freq);

	if (low_freq > high_freq)
	low_freq = high_freq;

	return 0;
	}


	static int longrun_cpu_init(struct cpufreq_policy *policy)
	{
	int result = 0;

	/* capability check */
	if (policy->cpu != 0)
	return -ENODEV;

	/* detect low and high frequency */
	result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
	if (result)
	return result;

	/* cpuinfo and default policy values */
	policy->cpuinfo.min_freq = longrun_low_freq;
	policy->cpuinfo.max_freq = longrun_high_freq;
	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
	longrun_get_policy(policy);

	return 0;
	}


	static struct cpufreq_driver longrun_driver = {
	.flags = CPUFREQ_CONST_LOOPS,
	.verify = longrun_verify_policy,
	.setpolicy = longrun_set_policy,
	.get = longrun_get,
	.init = longrun_cpu_init,
	.name = "longrun",
	};

	static const struct x86_cpu_id longrun_ids[] = {
	{ X86_VENDOR_TRANSMETA, X86_FAMILY_ANY, X86_MODEL_ANY,
	X86_FEATURE_LONGRUN },
	{}
	};
	MODULE_DEVICE_TABLE(x86cpu, longrun_ids);

	/**
	* longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
	*
	* Initializes the LongRun support.
	*/
	static int __init longrun_init(void)
	{
	if (!x86_match_cpu(longrun_ids))
	return -ENODEV;
	return cpufreq_register_driver(&longrun_driver);
	}


	/**
	* longrun_exit - unregisters LongRun support
	*/
	static void __exit longrun_exit(void)
	{
	cpufreq_unregister_driver(&longrun_driver);
	}


	MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
	MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
	"Efficeon processors.");
	MODULE_LICENSE("GPL");

	module_init(longrun_init);
	module_exit(longrun_exit);