speedstep.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

		{  66, 0x0 },
		{ 100, 0x2 },
		{ 133, 0x1 },
		{   0, 0xff}
	};
	u32     msr_lo, msr_tmp;
	int     i = 0, j = 0;
	struct  cpuinfo_x86 *c = cpu_data;

	/* read MSR 0x2a - we only need the low 32 bits */
	rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
	dprintk(KERN_DEBUG "cpufreq: P3 - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
	msr_tmp = msr_lo;

	/* decode the FSB */
	msr_tmp &= 0x00c0000;
	msr_tmp >>= 18;
	while (msr_tmp != msr_decode_fsb[i].bitmap) {
		if (msr_decode_fsb[i].bitmap == 0xff)
			return -EINVAL;
		i++;
	}

	/* decode the multiplier */
	if ((c->x86_model == 0x08) && (c->x86_mask == 0x01)) 
                /* different on early Coppermine PIII */
		msr_lo &= 0x03c00000;
	else
		msr_lo &= 0x0bc00000;
	msr_lo >>= 22;
	while (msr_lo != msr_decode_mult[j].bitmap) {
		if (msr_decode_mult[j].bitmap == 0xff)
			return -EINVAL;
		j++;
	}

	return (msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100);
}


/**
 * pentium4_get_frequency - get the core frequency for P4-Ms
 *
 *   Should return the core frequency (in kHz) for P4-Ms. 
 */
static unsigned int pentium4_get_frequency(void)
{
	u32 msr_lo, msr_hi;

	rdmsr(0x2c, msr_lo, msr_hi);

	dprintk(KERN_DEBUG "cpufreq: P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi);

	/* First 12 bits seem to change a lot (0x511, 0x410 and 0x30f seen 
	 * yet). Next 12 bits always seem to be 0x300. If this is not true 
	 * on this CPU, complain. Last 8 bits are frequency (in 100MHz).
	 */
	if (msr_hi || ((msr_lo & 0x00FFF000) != 0x300000)) {
		printk(KERN_DEBUG "cpufreq: P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi);
		printk(KERN_INFO "cpufreq: problem in initialization. Please contact Dominik Brodowski\n");
		printk(KERN_INFO "cpufreq: <[e-mail]> and attach this dmesg. Thanks in advance\n");
		return 0;
	}

	msr_lo >>= 24;
	return (msr_lo * 100000);
}


/** 
 * speedstep_detect_processor - detect Intel SpeedStep-capable processors.
 *
 *   Returns the SPEEDSTEP_PROCESSOR_-number for the detected processor, 
 * or zero on failure.
 */
static unsigned int speedstep_detect_processor (void)
{
	struct cpuinfo_x86 *c = cpu_data;
	u32                     ebx;

	if ((c->x86_vendor != X86_VENDOR_INTEL) || 
	    ((c->x86 != 6) && (c->x86 != 0xF)))
		return 0;

	if (c->x86 == 0xF) {
		/* Intel Pentium 4 Mobile P4-M */
		if (c->x86_model != 2)
			return 0;

		if ((c->x86_mask != 4) && (c->x86_mask != 7))
			return 0;

		ebx = cpuid_ebx(0x00000001);
		ebx &= 0x000000FF;
		if ((ebx != 0x0e) && (ebx != 0x0f))
			return 0;

		return SPEEDSTEP_PROCESSOR_P4M;
	}

	switch (c->x86_model) {
	case 0x0B: /* Intel PIII [Tualatin] */
		/* cpuid_ebx(1) is 0x04 for desktop PIII, 
		                   0x06 for mobile PIII-M */
		ebx = cpuid_ebx(0x00000001);

		ebx &= 0x000000FF;
		if (ebx != 0x06)
			return 0;

		/* So far all PIII-M processors support SpeedStep. See
		 * Intel's 24540633.pdf of August 2002 
		 */

		return SPEEDSTEP_PROCESSOR_PIII_T;

	case 0x08: /* Intel PIII [Coppermine] */
 	        {
			u32     msr_lo, msr_hi;

			/* all mobile PIII Coppermines have FSB 100 MHz
			 * ==> sort out a few desktop PIIIs. */
			rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_hi);
			dprintk(KERN_DEBUG "cpufreq: Coppermine: MSR_IA32_EBL_Cr_POWERON is 0x%x, 0x%x\n", msr_lo, msr_hi);
			msr_lo &= 0x00c0000;
			if (msr_lo != 0x0080000)
				return 0;

			if (speedstep_coppermine)
				return SPEEDSTEP_PROCESSOR_PIII_C;

			printk(KERN_INFO "cpufreq: in case this is a SpeedStep-capable Intel Pentium III Coppermine\n");
			printk(KERN_INFO "cpufreq: processor, please pass the boot option or module parameter\n");
			printk(KERN_INFO "cpufreq: `speedstep_coppermine=1` to the kernel. Thanks!\n");
			return 0;
		}

	default:
		return 0;
	}
}



/*********************************************************************
 *                        HIGH LEVEL FUNCTIONS                       *
 *********************************************************************/

/**
 * speedstep_detect_speeds - detects low and high CPU frequencies.
 *
 *   Detects the low and high CPU frequencies in kHz. Returns 0 on
 * success or -EINVAL / -EIO on problems. 
 */
static int speedstep_detect_speeds (void)
{
	unsigned long   flags;
	unsigned int    state;
	int             i, result;

	/* Disable irqs for entire detection process */
	local_irq_save(flags);

	for (i=0; i<2; i++) {
		/* read the current state */
		result = speedstep_get_state(&state);
		if (result)
			return result;

		/* save the correct value, and switch to other */
		if (state == SPEEDSTEP_LOW) {
			switch (speedstep_processor) {
			case SPEEDSTEP_PROCESSOR_PIII_C:
			case SPEEDSTEP_PROCESSOR_PIII_T:
				speedstep_low_freq = pentium3_get_frequency();
				break;
			case SPEEDSTEP_PROCESSOR_P4M:
				speedstep_low_freq = pentium4_get_frequency();
			}
			speedstep_set_state(SPEEDSTEP_HIGH, 0);
		} else {
			switch (speedstep_processor) {
			case SPEEDSTEP_PROCESSOR_PIII_C:
			case SPEEDSTEP_PROCESSOR_PIII_T:
				speedstep_high_freq = pentium3_get_frequency();
				break;
			case SPEEDSTEP_PROCESSOR_P4M:
				speedstep_high_freq = pentium4_get_frequency();
			}
			speedstep_set_state(SPEEDSTEP_LOW, 0);
		}
	}

	local_irq_restore(flags);

	if (!speedstep_low_freq || !speedstep_high_freq || 
	    (speedstep_low_freq == speedstep_high_freq))
		return -EIO;

	return 0;
}


/**
 * speedstep_setpolicy - set a new CPUFreq policy
 * @policy: new policy
 *
 * Sets a new CPUFreq policy.
 */
static int speedstep_setpolicy (struct cpufreq_policy *policy)
{
	unsigned int    newstate = 0;

	if (cpufreq_frequency_table_setpolicy(policy, &speedstep_freqs[0], &newstate))
		return -EINVAL;

	speedstep_set_state(newstate, 1);

	return 0;
}


/**
 * speedstep_verify - verifies a new CPUFreq policy
 * @freq: new policy
 *
 * Limit must be within speedstep_low_freq and speedstep_high_freq, with
 * at least one border included.
 */
static int speedstep_verify (struct cpufreq_policy *policy)
{
	return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
}


#ifndef MODULE
/**
 * speedstep_setup  speedstep command line parameter parsing
 *
 * speedstep command line parameter.  Use:
 *  speedstep_coppermine=1
 * if the CPU in your notebook is a SpeedStep-capable Intel
 * Pentium III Coppermine. These processors cannot be detected
 * automatically, as Intel continues to consider the detection 
 * alogrithm as proprietary material.
 */
static int __init speedstep_setup(char *str)
{
	speedstep_coppermine = simple_strtoul(str, &str, 0);
	return 1;
}
__setup("speedstep_coppermine=", speedstep_setup);
#endif

/**
 * speedstep_init - initializes the SpeedStep CPUFreq driver
 *
 *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 * devices, -EINVAL on problems during initiatization, and zero on
 * success.
 */
static int __init speedstep_init(void)
{
	int                     result;
	unsigned int            speed;
	struct cpufreq_driver   *driver;


	/* detect chipset */
	speedstep_chipset = speedstep_detect_chipset(); 

	/* detect chipset */
	if (speedstep_chipset)
		speedstep_processor = speedstep_detect_processor();

	if ((!speedstep_chipset) || (!speedstep_processor)) {
		printk(KERN_INFO "cpufreq: Intel(R) SpeedStep(TM) for this %s not (yet) available.\n", speedstep_chipset ? "processor" : "chipset");
		return -ENODEV;
	}

	dprintk(KERN_INFO "cpufreq: Intel(R) SpeedStep(TM) support $Revision: 1.64 $\n");
	dprintk(KERN_DEBUG "cpufreq: chipset 0x%x - processor 0x%x\n", 
	       speedstep_chipset, speedstep_processor);

	/* activate speedstep support */
	result = speedstep_activate();
	if (result)
		return result;

	/* detect low and high frequency */
	result = speedstep_detect_speeds();
	if (result)
		return result;

	/* get current speed setting */
	result = speedstep_get_state(&speed);
	if (result)
		return result;

	speed = (speed == SPEEDSTEP_LOW) ? speedstep_low_freq : speedstep_high_freq;

	dprintk(KERN_INFO "cpufreq: currently at %s speed setting - %i MHz\n", 
	       (speed == speedstep_low_freq) ? "low" : "high",
	       (speed / 1000));

	/* initialization of main "cpufreq" code*/
	driver = kmalloc(sizeof(struct cpufreq_driver) + 
			 NR_CPUS * sizeof(struct cpufreq_policy), GFP_KERNEL);
	if (!driver)
		return -ENOMEM;

	driver->policy = (struct cpufreq_policy *) (driver + 1);

	driver->policy[0].cpu    = 0;
	result = cpufreq_frequency_table_cpuinfo(&driver->policy[0], &speedstep_freqs[0]);
	if (result) {
		kfree(driver);
		return result;
	}

#ifdef CONFIG_CPU_FREQ_24_API
	driver->cpu_cur_freq[0] = speed;
#endif

	driver->verify      = &speedstep_verify;
	driver->setpolicy   = &speedstep_setpolicy;

	driver->policy[0].cpuinfo.transition_latency = CPUFREQ_ETERNAL;

	driver->policy[0].policy = (speed == speedstep_low_freq) ? 
	    CPUFREQ_POLICY_POWERSAVE : CPUFREQ_POLICY_PERFORMANCE;

	speedstep_driver = driver;

	result = cpufreq_register(driver);
	if (result) {
		speedstep_driver = NULL;
		kfree(driver);
	}

	return result;
}


/**
 * speedstep_exit - unregisters SpeedStep support
 *
 *   Unregisters SpeedStep support.
 */
static void __exit speedstep_exit(void)
{
	if (speedstep_driver) {
		cpufreq_unregister();
		kfree(speedstep_driver);
	}
}


MODULE_AUTHOR ("Dave Jones <[e-mail]>, Dominik Brodowski <[e-mail]>");
MODULE_DESCRIPTION ("Speedstep driver for Intel mobile processors.");
MODULE_LICENSE ("GPL");
module_init(speedstep_init);
module_exit(speedstep_exit);

MODULE_PARM (speedstep_coppermine, "i");