2 * Intel SpeedStep SMI driver.
4 * (C) 2003 Hiroshi Miura <miura@da-cha.org>
6 * Licensed under the terms of the GNU GPL License version 2.
11 /*********************************************************************
12 * SPEEDSTEP - DEFINITIONS *
13 *********************************************************************/
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/init.h>
19 #include <linux/cpufreq.h>
20 #include <linux/delay.h>
23 #include <asm/cpu_device_id.h>
25 #include "speedstep-lib.h"
27 /* speedstep system management interface port/command.
29 * These parameters are got from IST-SMI BIOS call.
30 * If user gives it, these are used.
35 static unsigned int smi_sig;
37 /* info about the processor */
38 static enum speedstep_processor speedstep_processor;
41 * There are only two frequency states for each processor. Values
42 * are in kHz for the time being.
44 static struct cpufreq_frequency_table speedstep_freqs[] = {
47 {0, CPUFREQ_TABLE_END},
50 #define GET_SPEEDSTEP_OWNER 0
51 #define GET_SPEEDSTEP_STATE 1
52 #define SET_SPEEDSTEP_STATE 2
53 #define GET_SPEEDSTEP_FREQS 4
55 /* how often shall the SMI call be tried if it failed, e.g. because
56 * of DMA activity going on? */
60 * speedstep_smi_ownership
62 static int speedstep_smi_ownership(void)
64 u32 command, result, magic, dummy;
65 u32 function = GET_SPEEDSTEP_OWNER;
66 unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
68 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
69 magic = virt_to_phys(magic_data);
71 pr_debug("trying to obtain ownership with command %x at port %x\n",
79 "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
81 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
86 pr_debug("result is %x\n", result);
92 * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
93 * @low: the low frequency value is placed here
94 * @high: the high frequency value is placed here
96 * Only available on later SpeedStep-enabled systems, returns false results or
97 * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
98 * shows that the latter occurs if !(ist_info.event & 0xFFFF).
100 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
102 u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
104 u32 function = GET_SPEEDSTEP_FREQS;
106 if (!(ist_info.event & 0xFFFF)) {
107 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
111 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
113 pr_debug("trying to determine frequencies with command %x at port %x\n",
116 __asm__ __volatile__(
123 "=d" (state), "=D" (edi), "=S" (dummy)
127 "d" (smi_port), "S" (0), "D" (0)
130 pr_debug("result %x, low_freq %u, high_freq %u\n",
131 result, low_mhz, high_mhz);
133 /* abort if results are obviously incorrect... */
134 if ((high_mhz + low_mhz) < 600)
137 *high = high_mhz * 1000;
138 *low = low_mhz * 1000;
144 * speedstep_get_state - set the SpeedStep state
145 * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
148 static int speedstep_get_state(void)
150 u32 function = GET_SPEEDSTEP_STATE;
151 u32 result, state, edi, command, dummy;
153 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
155 pr_debug("trying to determine current setting with command %x "
156 "at port %x\n", command, smi_port);
158 __asm__ __volatile__(
163 "=b" (state), "=D" (edi),
164 "=c" (dummy), "=d" (dummy), "=S" (dummy)
165 : "a" (command), "b" (function), "c" (0),
166 "d" (smi_port), "S" (0), "D" (0)
169 pr_debug("state is %x, result is %x\n", state, result);
176 * speedstep_set_state - set the SpeedStep state
177 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
180 static void speedstep_set_state(unsigned int state)
182 unsigned int result = 0, command, new_state, dummy;
184 unsigned int function = SET_SPEEDSTEP_STATE;
185 unsigned int retry = 0;
191 local_irq_save(flags);
193 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
195 pr_debug("trying to set frequency to state %u "
196 "with command %x at port %x\n",
197 state, command, smi_port);
201 pr_debug("retry %u, previous result %u, waiting...\n",
206 __asm__ __volatile__(
210 : "=b" (new_state), "=D" (result),
211 "=c" (dummy), "=a" (dummy),
212 "=d" (dummy), "=S" (dummy)
213 : "a" (command), "b" (function), "c" (state),
214 "d" (smi_port), "S" (0), "D" (0)
216 } while ((new_state != state) && (retry <= SMI_TRIES));
219 local_irq_restore(flags);
221 if (new_state == state)
222 pr_debug("change to %u MHz succeeded after %u tries "
224 (speedstep_freqs[new_state].frequency / 1000),
227 printk(KERN_ERR "cpufreq: change to state %u "
228 "failed with new_state %u and result %u\n",
229 state, new_state, result);
236 * speedstep_target - set a new CPUFreq policy
237 * @policy: new policy
238 * @target_freq: new freq
241 * Sets a new CPUFreq policy/freq.
243 static int speedstep_target(struct cpufreq_policy *policy,
244 unsigned int target_freq, unsigned int relation)
246 unsigned int newstate = 0;
247 struct cpufreq_freqs freqs;
249 if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
250 target_freq, relation, &newstate))
253 freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
254 freqs.new = speedstep_freqs[newstate].frequency;
256 if (freqs.old == freqs.new)
259 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
260 speedstep_set_state(newstate);
261 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
267 static int speedstep_cpu_init(struct cpufreq_policy *policy)
270 unsigned int speed, state;
271 unsigned int *low, *high;
273 /* capability check */
274 if (policy->cpu != 0)
277 result = speedstep_smi_ownership();
279 pr_debug("fails in acquiring ownership of a SMI interface.\n");
283 /* detect low and high frequency */
284 low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
285 high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
287 result = speedstep_smi_get_freqs(low, high);
289 /* fall back to speedstep_lib.c dection mechanism:
290 * try both states out */
291 pr_debug("could not detect low and high frequencies "
293 result = speedstep_get_freqs(speedstep_processor,
296 &speedstep_set_state);
299 pr_debug("could not detect two different speeds"
303 pr_debug("workaround worked.\n");
306 /* get current speed setting */
307 state = speedstep_get_state();
308 speed = speedstep_freqs[state].frequency;
310 pr_debug("currently at %s speed setting - %i MHz\n",
311 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
315 /* cpuinfo and default policy values */
316 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
319 return cpufreq_table_validate_and_show(policy, speedstep_freqs);
322 static unsigned int speedstep_get(unsigned int cpu)
326 return speedstep_get_frequency(speedstep_processor);
330 static int speedstep_resume(struct cpufreq_policy *policy)
332 int result = speedstep_smi_ownership();
335 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
340 static struct cpufreq_driver speedstep_driver = {
341 .name = "speedstep-smi",
342 .verify = cpufreq_generic_frequency_table_verify,
343 .target = speedstep_target,
344 .init = speedstep_cpu_init,
345 .exit = cpufreq_generic_exit,
346 .get = speedstep_get,
347 .resume = speedstep_resume,
348 .attr = cpufreq_generic_attr,
351 static const struct x86_cpu_id ss_smi_ids[] = {
352 { X86_VENDOR_INTEL, 6, 0xb, },
353 { X86_VENDOR_INTEL, 6, 0x8, },
354 { X86_VENDOR_INTEL, 15, 2 },
358 /* Not auto loaded currently */
359 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
363 * speedstep_init - initializes the SpeedStep CPUFreq driver
365 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
366 * BIOS, -EINVAL on problems during initiatization, and zero on
369 static int __init speedstep_init(void)
371 if (!x86_match_cpu(ss_smi_ids))
374 speedstep_processor = speedstep_detect_processor();
376 switch (speedstep_processor) {
377 case SPEEDSTEP_CPU_PIII_T:
378 case SPEEDSTEP_CPU_PIII_C:
379 case SPEEDSTEP_CPU_PIII_C_EARLY:
382 speedstep_processor = 0;
385 if (!speedstep_processor) {
386 pr_debug("No supported Intel CPU detected.\n");
390 pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
391 "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
392 ist_info.signature, ist_info.command,
393 ist_info.event, ist_info.perf_level);
395 /* Error if no IST-SMI BIOS or no PARM
396 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
397 if ((ist_info.signature != 0x47534943) && (
398 (smi_port == 0) || (smi_cmd == 0)))
402 smi_sig = 0x47534943;
404 smi_sig = ist_info.signature;
406 /* setup smi_port from MODLULE_PARM or BIOS */
407 if ((smi_port > 0xff) || (smi_port < 0))
409 else if (smi_port == 0)
410 smi_port = ist_info.command & 0xff;
412 if ((smi_cmd > 0xff) || (smi_cmd < 0))
414 else if (smi_cmd == 0)
415 smi_cmd = (ist_info.command >> 16) & 0xff;
417 return cpufreq_register_driver(&speedstep_driver);
422 * speedstep_exit - unregisters SpeedStep support
424 * Unregisters SpeedStep support.
426 static void __exit speedstep_exit(void)
428 cpufreq_unregister_driver(&speedstep_driver);
431 module_param(smi_port, int, 0444);
432 module_param(smi_cmd, int, 0444);
433 module_param(smi_sig, uint, 0444);
435 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
436 "-- Intel's default setting is 0xb2");
437 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
438 "-- Intel's default setting is 0x82");
439 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
442 MODULE_AUTHOR("Hiroshi Miura");
443 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
444 MODULE_LICENSE("GPL");
446 module_init(speedstep_init);
447 module_exit(speedstep_exit);