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;
192 local_irq_save(flags);
194 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
196 pr_debug("trying to set frequency to state %u "
197 "with command %x at port %x\n",
198 state, command, smi_port);
203 * We need to enable interrupts, otherwise the blockage
206 * We disable preemption so that other processes don't
207 * run. If other processes were running, they could
208 * submit more DMA requests, making the blockage worse.
210 pr_debug("retry %u, previous result %u, waiting...\n",
217 __asm__ __volatile__(
221 : "=b" (new_state), "=D" (result),
222 "=c" (dummy), "=a" (dummy),
223 "=d" (dummy), "=S" (dummy)
224 : "a" (command), "b" (function), "c" (state),
225 "d" (smi_port), "S" (0), "D" (0)
227 } while ((new_state != state) && (retry <= SMI_TRIES));
230 local_irq_restore(flags);
233 if (new_state == state)
234 pr_debug("change to %u MHz succeeded after %u tries "
236 (speedstep_freqs[new_state].frequency / 1000),
239 printk(KERN_ERR "cpufreq: change to state %u "
240 "failed with new_state %u and result %u\n",
241 state, new_state, result);
248 * speedstep_target - set a new CPUFreq policy
249 * @policy: new policy
250 * @target_freq: new freq
253 * Sets a new CPUFreq policy/freq.
255 static int speedstep_target(struct cpufreq_policy *policy,
256 unsigned int target_freq, unsigned int relation)
258 unsigned int newstate = 0;
259 struct cpufreq_freqs freqs;
261 if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
262 target_freq, relation, &newstate))
265 freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
266 freqs.new = speedstep_freqs[newstate].frequency;
268 if (freqs.old == freqs.new)
271 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
272 speedstep_set_state(newstate);
273 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
280 * speedstep_verify - verifies a new CPUFreq policy
281 * @policy: new policy
283 * Limit must be within speedstep_low_freq and speedstep_high_freq, with
284 * at least one border included.
286 static int speedstep_verify(struct cpufreq_policy *policy)
288 return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
292 static int speedstep_cpu_init(struct cpufreq_policy *policy)
295 unsigned int speed, state;
296 unsigned int *low, *high;
298 /* capability check */
299 if (policy->cpu != 0)
302 result = speedstep_smi_ownership();
304 pr_debug("fails in acquiring ownership of a SMI interface.\n");
308 /* detect low and high frequency */
309 low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
310 high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
312 result = speedstep_smi_get_freqs(low, high);
314 /* fall back to speedstep_lib.c dection mechanism:
315 * try both states out */
316 pr_debug("could not detect low and high frequencies "
318 result = speedstep_get_freqs(speedstep_processor,
321 &speedstep_set_state);
324 pr_debug("could not detect two different speeds"
328 pr_debug("workaround worked.\n");
331 /* get current speed setting */
332 state = speedstep_get_state();
333 speed = speedstep_freqs[state].frequency;
335 pr_debug("currently at %s speed setting - %i MHz\n",
336 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
340 /* cpuinfo and default policy values */
341 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
344 result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
348 cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
353 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
355 cpufreq_frequency_table_put_attr(policy->cpu);
359 static unsigned int speedstep_get(unsigned int cpu)
363 return speedstep_get_frequency(speedstep_processor);
367 static int speedstep_resume(struct cpufreq_policy *policy)
369 int result = speedstep_smi_ownership();
372 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
377 static struct freq_attr *speedstep_attr[] = {
378 &cpufreq_freq_attr_scaling_available_freqs,
382 static struct cpufreq_driver speedstep_driver = {
383 .name = "speedstep-smi",
384 .verify = speedstep_verify,
385 .target = speedstep_target,
386 .init = speedstep_cpu_init,
387 .exit = speedstep_cpu_exit,
388 .get = speedstep_get,
389 .resume = speedstep_resume,
390 .owner = THIS_MODULE,
391 .attr = speedstep_attr,
394 static const struct x86_cpu_id ss_smi_ids[] = {
395 { X86_VENDOR_INTEL, 6, 0xb, },
396 { X86_VENDOR_INTEL, 6, 0x8, },
397 { X86_VENDOR_INTEL, 15, 2 },
401 /* Not auto loaded currently */
402 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
406 * speedstep_init - initializes the SpeedStep CPUFreq driver
408 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
409 * BIOS, -EINVAL on problems during initiatization, and zero on
412 static int __init speedstep_init(void)
414 if (!x86_match_cpu(ss_smi_ids))
417 speedstep_processor = speedstep_detect_processor();
419 switch (speedstep_processor) {
420 case SPEEDSTEP_CPU_PIII_T:
421 case SPEEDSTEP_CPU_PIII_C:
422 case SPEEDSTEP_CPU_PIII_C_EARLY:
425 speedstep_processor = 0;
428 if (!speedstep_processor) {
429 pr_debug("No supported Intel CPU detected.\n");
433 pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
434 "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
435 ist_info.signature, ist_info.command,
436 ist_info.event, ist_info.perf_level);
438 /* Error if no IST-SMI BIOS or no PARM
439 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
440 if ((ist_info.signature != 0x47534943) && (
441 (smi_port == 0) || (smi_cmd == 0)))
445 smi_sig = 0x47534943;
447 smi_sig = ist_info.signature;
449 /* setup smi_port from MODLULE_PARM or BIOS */
450 if ((smi_port > 0xff) || (smi_port < 0))
452 else if (smi_port == 0)
453 smi_port = ist_info.command & 0xff;
455 if ((smi_cmd > 0xff) || (smi_cmd < 0))
457 else if (smi_cmd == 0)
458 smi_cmd = (ist_info.command >> 16) & 0xff;
460 return cpufreq_register_driver(&speedstep_driver);
465 * speedstep_exit - unregisters SpeedStep support
467 * Unregisters SpeedStep support.
469 static void __exit speedstep_exit(void)
471 cpufreq_unregister_driver(&speedstep_driver);
474 module_param(smi_port, int, 0444);
475 module_param(smi_cmd, int, 0444);
476 module_param(smi_sig, uint, 0444);
478 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
479 "-- Intel's default setting is 0xb2");
480 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
481 "-- Intel's default setting is 0x82");
482 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
485 MODULE_AUTHOR("Hiroshi Miura");
486 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
487 MODULE_LICENSE("GPL");
489 module_init(speedstep_init);
490 module_exit(speedstep_exit);