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* Intel SpeedStep SMI driver.
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* (C) 2003 Hiroshi Miura <miura@da-cha.org>
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* Licensed under the terms of the GNU GPL License version 2.
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/*********************************************************************
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* SPEEDSTEP - DEFINITIONS *
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*********************************************************************/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/cpufreq.h>
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#include <linux/delay.h>
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#include "speedstep-lib.h"
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/* speedstep system management interface port/command.
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* These parameters are got from IST-SMI BIOS call.
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* If user gives it, these are used.
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static unsigned int smi_sig;
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/* info about the processor */
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static enum speedstep_processor speedstep_processor;
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* There are only two frequency states for each processor. Values
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* are in kHz for the time being.
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static struct cpufreq_frequency_table speedstep_freqs[] = {
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{0, CPUFREQ_TABLE_END},
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#define GET_SPEEDSTEP_OWNER 0
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#define GET_SPEEDSTEP_STATE 1
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#define SET_SPEEDSTEP_STATE 2
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#define GET_SPEEDSTEP_FREQS 4
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/* how often shall the SMI call be tried if it failed, e.g. because
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* of DMA activity going on? */
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* speedstep_smi_ownership
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static int speedstep_smi_ownership(void)
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u32 command, result, magic, dummy;
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u32 function = GET_SPEEDSTEP_OWNER;
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unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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magic = virt_to_phys(magic_data);
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pr_debug("trying to obtain ownership with command %x at port %x\n",
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"=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
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: "a" (command), "b" (function), "c" (0), "d" (smi_port),
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pr_debug("result is %x\n", result);
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* speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
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* @low: the low frequency value is placed here
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* @high: the high frequency value is placed here
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* Only available on later SpeedStep-enabled systems, returns false results or
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* even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
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* shows that the latter occurs if !(ist_info.event & 0xFFFF).
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static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
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u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
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u32 function = GET_SPEEDSTEP_FREQS;
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if (!(ist_info.event & 0xFFFF)) {
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pr_debug("bug #1422 -- can't read freqs from BIOS\n");
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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pr_debug("trying to determine frequencies with command %x at port %x\n",
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__asm__ __volatile__(
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"=d" (state), "=D" (edi), "=S" (dummy)
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"d" (smi_port), "S" (0), "D" (0)
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pr_debug("result %x, low_freq %u, high_freq %u\n",
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result, low_mhz, high_mhz);
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/* abort if results are obviously incorrect... */
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if ((high_mhz + low_mhz) < 600)
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*high = high_mhz * 1000;
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*low = low_mhz * 1000;
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* speedstep_get_state - set the SpeedStep state
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* @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
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static int speedstep_get_state(void)
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u32 function = GET_SPEEDSTEP_STATE;
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u32 result, state, edi, command, dummy;
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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pr_debug("trying to determine current setting with command %x "
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"at port %x\n", command, smi_port);
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__asm__ __volatile__(
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"=b" (state), "=D" (edi),
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"=c" (dummy), "=d" (dummy), "=S" (dummy)
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: "a" (command), "b" (function), "c" (0),
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"d" (smi_port), "S" (0), "D" (0)
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pr_debug("state is %x, result is %x\n", state, result);
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* speedstep_set_state - set the SpeedStep state
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* @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
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static void speedstep_set_state(unsigned int state)
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unsigned int result = 0, command, new_state, dummy;
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unsigned int function = SET_SPEEDSTEP_STATE;
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unsigned int retry = 0;
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local_irq_save(flags);
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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pr_debug("trying to set frequency to state %u "
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"with command %x at port %x\n",
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state, command, smi_port);
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pr_debug("retry %u, previous result %u, waiting...\n",
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__asm__ __volatile__(
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: "=b" (new_state), "=D" (result),
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"=c" (dummy), "=a" (dummy),
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"=d" (dummy), "=S" (dummy)
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: "a" (command), "b" (function), "c" (state),
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"d" (smi_port), "S" (0), "D" (0)
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} while ((new_state != state) && (retry <= SMI_TRIES));
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local_irq_restore(flags);
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if (new_state == state)
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pr_debug("change to %u MHz succeeded after %u tries "
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(speedstep_freqs[new_state].frequency / 1000),
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printk(KERN_ERR "cpufreq: change to state %u "
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"failed with new_state %u and result %u\n",
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state, new_state, result);
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* speedstep_target - set a new CPUFreq policy
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* @policy: new policy
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* @target_freq: new freq
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* Sets a new CPUFreq policy/freq.
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static int speedstep_target(struct cpufreq_policy *policy,
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unsigned int target_freq, unsigned int relation)
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unsigned int newstate = 0;
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struct cpufreq_freqs freqs;
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if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
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target_freq, relation, &newstate))
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freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
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freqs.new = speedstep_freqs[newstate].frequency;
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freqs.cpu = 0; /* speedstep.c is UP only driver */
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if (freqs.old == freqs.new)
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cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
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speedstep_set_state(newstate);
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cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
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* speedstep_verify - verifies a new CPUFreq policy
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* @policy: new policy
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* Limit must be within speedstep_low_freq and speedstep_high_freq, with
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* at least one border included.
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static int speedstep_verify(struct cpufreq_policy *policy)
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return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
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static int speedstep_cpu_init(struct cpufreq_policy *policy)
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unsigned int speed, state;
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unsigned int *low, *high;
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/* capability check */
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if (policy->cpu != 0)
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result = speedstep_smi_ownership();
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pr_debug("fails in acquiring ownership of a SMI interface.\n");
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/* detect low and high frequency */
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low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
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high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
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result = speedstep_smi_get_freqs(low, high);
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/* fall back to speedstep_lib.c dection mechanism:
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* try both states out */
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pr_debug("could not detect low and high frequencies "
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result = speedstep_get_freqs(speedstep_processor,
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&speedstep_set_state);
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pr_debug("could not detect two different speeds"
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pr_debug("workaround worked.\n");
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/* get current speed setting */
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state = speedstep_get_state();
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speed = speedstep_freqs[state].frequency;
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pr_debug("currently at %s speed setting - %i MHz\n",
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(speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
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/* cpuinfo and default policy values */
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
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cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
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static int speedstep_cpu_exit(struct cpufreq_policy *policy)
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cpufreq_frequency_table_put_attr(policy->cpu);
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static unsigned int speedstep_get(unsigned int cpu)
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return speedstep_get_frequency(speedstep_processor);
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static int speedstep_resume(struct cpufreq_policy *policy)
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int result = speedstep_smi_ownership();
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pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
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static struct freq_attr *speedstep_attr[] = {
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&cpufreq_freq_attr_scaling_available_freqs,
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static struct cpufreq_driver speedstep_driver = {
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.name = "speedstep-smi",
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.verify = speedstep_verify,
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.target = speedstep_target,
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.init = speedstep_cpu_init,
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.exit = speedstep_cpu_exit,
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.get = speedstep_get,
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.resume = speedstep_resume,
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.owner = THIS_MODULE,
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.attr = speedstep_attr,
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* speedstep_init - initializes the SpeedStep CPUFreq driver
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* Initializes the SpeedStep support. Returns -ENODEV on unsupported
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* BIOS, -EINVAL on problems during initiatization, and zero on
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static int __init speedstep_init(void)
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speedstep_processor = speedstep_detect_processor();
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switch (speedstep_processor) {
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case SPEEDSTEP_CPU_PIII_T:
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case SPEEDSTEP_CPU_PIII_C:
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case SPEEDSTEP_CPU_PIII_C_EARLY:
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speedstep_processor = 0;
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if (!speedstep_processor) {
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pr_debug("No supported Intel CPU detected.\n");
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pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
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"event:0x%.8ulx, perf_level:0x%.8ulx.\n",
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ist_info.signature, ist_info.command,
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ist_info.event, ist_info.perf_level);
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/* Error if no IST-SMI BIOS or no PARM
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sig= 'ISGE' aka 'Intel Speedstep Gate E' */
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if ((ist_info.signature != 0x47534943) && (
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(smi_port == 0) || (smi_cmd == 0)))
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smi_sig = 0x47534943;
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smi_sig = ist_info.signature;
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/* setup smi_port from MODLULE_PARM or BIOS */
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if ((smi_port > 0xff) || (smi_port < 0))
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else if (smi_port == 0)
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smi_port = ist_info.command & 0xff;
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if ((smi_cmd > 0xff) || (smi_cmd < 0))
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else if (smi_cmd == 0)
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smi_cmd = (ist_info.command >> 16) & 0xff;
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return cpufreq_register_driver(&speedstep_driver);
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* speedstep_exit - unregisters SpeedStep support
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* Unregisters SpeedStep support.
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static void __exit speedstep_exit(void)
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cpufreq_unregister_driver(&speedstep_driver);
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module_param(smi_port, int, 0444);
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module_param(smi_cmd, int, 0444);
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module_param(smi_sig, uint, 0444);
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MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
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"-- Intel's default setting is 0xb2");
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MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
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"-- Intel's default setting is 0x82");
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MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
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MODULE_AUTHOR("Hiroshi Miura");
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MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
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MODULE_LICENSE("GPL");
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module_init(speedstep_init);
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module_exit(speedstep_exit);
added
removed
arch/x86/kernel/cpu/cpufreq/speedstep-smi.c
