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>
24 #include "speedstep-lib.h"
26 /* speedstep system management interface port/command.
28 * These parameters are got from IST-SMI BIOS call.
29 * If user gives it, these are used.
34 static unsigned int smi_sig;
36 /* info about the processor */
37 static enum speedstep_processor speedstep_processor;
40 * There are only two frequency states for each processor. Values
41 * are in kHz for the time being.
43 static struct cpufreq_frequency_table speedstep_freqs[] = {
46 {0, CPUFREQ_TABLE_END},
49 #define GET_SPEEDSTEP_OWNER 0
50 #define GET_SPEEDSTEP_STATE 1
51 #define SET_SPEEDSTEP_STATE 2
52 #define GET_SPEEDSTEP_FREQS 4
54 /* how often shall the SMI call be tried if it failed, e.g. because
55 * of DMA activity going on? */
59 * speedstep_smi_ownership
61 static int speedstep_smi_ownership(void)
63 u32 command, result, magic, dummy;
64 u32 function = GET_SPEEDSTEP_OWNER;
65 unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
67 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
68 magic = virt_to_phys(magic_data);
70 pr_debug("trying to obtain ownership with command %x at port %x\n",
78 "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
80 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
85 pr_debug("result is %x\n", result);
91 * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
92 * @low: the low frequency value is placed here
93 * @high: the high frequency value is placed here
95 * Only available on later SpeedStep-enabled systems, returns false results or
96 * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
97 * shows that the latter occurs if !(ist_info.event & 0xFFFF).
99 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
101 u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
103 u32 function = GET_SPEEDSTEP_FREQS;
105 if (!(ist_info.event & 0xFFFF)) {
106 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
110 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
112 pr_debug("trying to determine frequencies with command %x at port %x\n",
115 __asm__ __volatile__(
122 "=d" (state), "=D" (edi), "=S" (dummy)
126 "d" (smi_port), "S" (0), "D" (0)
129 pr_debug("result %x, low_freq %u, high_freq %u\n",
130 result, low_mhz, high_mhz);
132 /* abort if results are obviously incorrect... */
133 if ((high_mhz + low_mhz) < 600)
136 *high = high_mhz * 1000;
137 *low = low_mhz * 1000;
143 * speedstep_get_state - set the SpeedStep state
144 * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
147 static int speedstep_get_state(void)
149 u32 function = GET_SPEEDSTEP_STATE;
150 u32 result, state, edi, command, dummy;
152 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
154 pr_debug("trying to determine current setting with command %x "
155 "at port %x\n", command, smi_port);
157 __asm__ __volatile__(
162 "=b" (state), "=D" (edi),
163 "=c" (dummy), "=d" (dummy), "=S" (dummy)
164 : "a" (command), "b" (function), "c" (0),
165 "d" (smi_port), "S" (0), "D" (0)
168 pr_debug("state is %x, result is %x\n", state, result);
175 * speedstep_set_state - set the SpeedStep state
176 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
179 static void speedstep_set_state(unsigned int state)
181 unsigned int result = 0, command, new_state, dummy;
183 unsigned int function = SET_SPEEDSTEP_STATE;
184 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);
202 * We need to enable interrupts, otherwise the blockage
205 * We disable preemption so that other processes don't
206 * run. If other processes were running, they could
207 * submit more DMA requests, making the blockage worse.
209 pr_debug("retry %u, previous result %u, waiting...\n",
216 __asm__ __volatile__(
220 : "=b" (new_state), "=D" (result),
221 "=c" (dummy), "=a" (dummy),
222 "=d" (dummy), "=S" (dummy)
223 : "a" (command), "b" (function), "c" (state),
224 "d" (smi_port), "S" (0), "D" (0)
226 } while ((new_state != state) && (retry <= SMI_TRIES));
229 local_irq_restore(flags);
232 if (new_state == state)
233 pr_debug("change to %u MHz succeeded after %u tries "
235 (speedstep_freqs[new_state].frequency / 1000),
238 printk(KERN_ERR "cpufreq: change to state %u "
239 "failed with new_state %u and result %u\n",
240 state, new_state, result);
247 * speedstep_target - set a new CPUFreq policy
248 * @policy: new policy
249 * @target_freq: new freq
252 * Sets a new CPUFreq policy/freq.
254 static int speedstep_target(struct cpufreq_policy *policy,
255 unsigned int target_freq, unsigned int relation)
257 unsigned int newstate = 0;
258 struct cpufreq_freqs freqs;
260 if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
261 target_freq, relation, &newstate))
264 freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
265 freqs.new = speedstep_freqs[newstate].frequency;
266 freqs.cpu = 0; /* speedstep.c is UP only driver */
268 if (freqs.old == freqs.new)
271 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
272 speedstep_set_state(newstate);
273 cpufreq_notify_transition(&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,
395 * speedstep_init - initializes the SpeedStep CPUFreq driver
397 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
398 * BIOS, -EINVAL on problems during initiatization, and zero on
401 static int __init speedstep_init(void)
403 speedstep_processor = speedstep_detect_processor();
405 switch (speedstep_processor) {
406 case SPEEDSTEP_CPU_PIII_T:
407 case SPEEDSTEP_CPU_PIII_C:
408 case SPEEDSTEP_CPU_PIII_C_EARLY:
411 speedstep_processor = 0;
414 if (!speedstep_processor) {
415 pr_debug("No supported Intel CPU detected.\n");
419 pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
420 "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
421 ist_info.signature, ist_info.command,
422 ist_info.event, ist_info.perf_level);
424 /* Error if no IST-SMI BIOS or no PARM
425 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
426 if ((ist_info.signature != 0x47534943) && (
427 (smi_port == 0) || (smi_cmd == 0)))
431 smi_sig = 0x47534943;
433 smi_sig = ist_info.signature;
435 /* setup smi_port from MODLULE_PARM or BIOS */
436 if ((smi_port > 0xff) || (smi_port < 0))
438 else if (smi_port == 0)
439 smi_port = ist_info.command & 0xff;
441 if ((smi_cmd > 0xff) || (smi_cmd < 0))
443 else if (smi_cmd == 0)
444 smi_cmd = (ist_info.command >> 16) & 0xff;
446 return cpufreq_register_driver(&speedstep_driver);
451 * speedstep_exit - unregisters SpeedStep support
453 * Unregisters SpeedStep support.
455 static void __exit speedstep_exit(void)
457 cpufreq_unregister_driver(&speedstep_driver);
460 module_param(smi_port, int, 0444);
461 module_param(smi_cmd, int, 0444);
462 module_param(smi_sig, uint, 0444);
464 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
465 "-- Intel's default setting is 0xb2");
466 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
467 "-- Intel's default setting is 0x82");
468 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
471 MODULE_AUTHOR("Hiroshi Miura");
472 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
473 MODULE_LICENSE("GPL");
475 module_init(speedstep_init);
476 module_exit(speedstep_exit);