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Linux/arch/x86/kernel/cpu/cpufreq/speedstep-smi.c

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  1 /*
  2  * Intel SpeedStep SMI driver.
  3  *
  4  * (C) 2003  Hiroshi Miura <miura@da-cha.org>
  5  *
  6  *  Licensed under the terms of the GNU GPL License version 2.
  7  *
  8  */
  9 
 10 
 11 /*********************************************************************
 12  *                        SPEEDSTEP - DEFINITIONS                    *
 13  *********************************************************************/
 14 
 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/slab.h>
 21 #include <linux/delay.h>
 22 #include <linux/io.h>
 23 #include <asm/ist.h>
 24 
 25 #include "speedstep-lib.h"
 26 
 27 /* speedstep system management interface port/command.
 28  *
 29  * These parameters are got from IST-SMI BIOS call.
 30  * If user gives it, these are used.
 31  *
 32  */
 33 static int smi_port;
 34 static int smi_cmd;
 35 static unsigned int smi_sig;
 36 
 37 /* info about the processor */
 38 static unsigned int speedstep_processor;
 39 
 40 /*
 41  * There are only two frequency states for each processor. Values
 42  * are in kHz for the time being.
 43  */
 44 static struct cpufreq_frequency_table speedstep_freqs[] = {
 45         {SPEEDSTEP_HIGH,        0},
 46         {SPEEDSTEP_LOW,         0},
 47         {0,                     CPUFREQ_TABLE_END},
 48 };
 49 
 50 #define GET_SPEEDSTEP_OWNER 0
 51 #define GET_SPEEDSTEP_STATE 1
 52 #define SET_SPEEDSTEP_STATE 2
 53 #define GET_SPEEDSTEP_FREQS 4
 54 
 55 /* how often shall the SMI call be tried if it failed, e.g. because
 56  * of DMA activity going on? */
 57 #define SMI_TRIES 5
 58 
 59 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
 60                 "speedstep-smi", msg)
 61 
 62 /**
 63  * speedstep_smi_ownership
 64  */
 65 static int speedstep_smi_ownership(void)
 66 {
 67         u32 command, result, magic, dummy;
 68         u32 function = GET_SPEEDSTEP_OWNER;
 69         unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
 70 
 71         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 72         magic = virt_to_phys(magic_data);
 73 
 74         dprintk("trying to obtain ownership with command %x at port %x\n",
 75                         command, smi_port);
 76 
 77         __asm__ __volatile__(
 78                 "push %%ebp\n"
 79                 "out %%al, (%%dx)\n"
 80                 "pop %%ebp\n"
 81                 : "=D" (result),
 82                   "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
 83                   "=S" (dummy)
 84                 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
 85                   "D" (0), "S" (magic)
 86                 : "memory"
 87         );
 88 
 89         dprintk("result is %x\n", result);
 90 
 91         return result;
 92 }
 93 
 94 /**
 95  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
 96  * @low: the low frequency value is placed here
 97  * @high: the high frequency value is placed here
 98  *
 99  * Only available on later SpeedStep-enabled systems, returns false results or
100  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
101  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
102  */
103 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
104 {
105         u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
106         u32 state = 0;
107         u32 function = GET_SPEEDSTEP_FREQS;
108 
109         if (!(ist_info.event & 0xFFFF)) {
110                 dprintk("bug #1422 -- can't read freqs from BIOS\n");
111                 return -ENODEV;
112         }
113 
114         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
115 
116         dprintk("trying to determine frequencies with command %x at port %x\n",
117                         command, smi_port);
118 
119         __asm__ __volatile__(
120                 "push %%ebp\n"
121                 "out %%al, (%%dx)\n"
122                 "pop %%ebp"
123                 : "=a" (result),
124                   "=b" (high_mhz),
125                   "=c" (low_mhz),
126                   "=d" (state), "=D" (edi), "=S" (dummy)
127                 : "a" (command),
128                   "b" (function),
129                   "c" (state),
130                   "d" (smi_port), "S" (0), "D" (0)
131         );
132 
133         dprintk("result %x, low_freq %u, high_freq %u\n",
134                         result, low_mhz, high_mhz);
135 
136         /* abort if results are obviously incorrect... */
137         if ((high_mhz + low_mhz) < 600)
138                 return -EINVAL;
139 
140         *high = high_mhz * 1000;
141         *low  = low_mhz  * 1000;
142 
143         return result;
144 }
145 
146 /**
147  * speedstep_get_state - set the SpeedStep state
148  * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
149  *
150  */
151 static int speedstep_get_state(void)
152 {
153         u32 function = GET_SPEEDSTEP_STATE;
154         u32 result, state, edi, command, dummy;
155 
156         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
157 
158         dprintk("trying to determine current setting with command %x "
159                 "at port %x\n", command, smi_port);
160 
161         __asm__ __volatile__(
162                 "push %%ebp\n"
163                 "out %%al, (%%dx)\n"
164                 "pop %%ebp\n"
165                 : "=a" (result),
166                   "=b" (state), "=D" (edi),
167                   "=c" (dummy), "=d" (dummy), "=S" (dummy)
168                 : "a" (command), "b" (function), "c" (0),
169                   "d" (smi_port), "S" (0), "D" (0)
170         );
171 
172         dprintk("state is %x, result is %x\n", state, result);
173 
174         return state & 1;
175 }
176 
177 
178 /**
179  * speedstep_set_state - set the SpeedStep state
180  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
181  *
182  */
183 static void speedstep_set_state(unsigned int state)
184 {
185         unsigned int result = 0, command, new_state, dummy;
186         unsigned long flags;
187         unsigned int function = SET_SPEEDSTEP_STATE;
188         unsigned int retry = 0;
189 
190         if (state > 0x1)
191                 return;
192 
193         /* Disable IRQs */
194         local_irq_save(flags);
195 
196         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
197 
198         dprintk("trying to set frequency to state %u "
199                 "with command %x at port %x\n",
200                 state, command, smi_port);
201 
202         do {
203                 if (retry) {
204                         dprintk("retry %u, previous result %u, waiting...\n",
205                                         retry, result);
206                         mdelay(retry * 50);
207                 }
208                 retry++;
209                 __asm__ __volatile__(
210                         "push %%ebp\n"
211                         "out %%al, (%%dx)\n"
212                         "pop %%ebp"
213                         : "=b" (new_state), "=D" (result),
214                           "=c" (dummy), "=a" (dummy),
215                           "=d" (dummy), "=S" (dummy)
216                         : "a" (command), "b" (function), "c" (state),
217                           "d" (smi_port), "S" (0), "D" (0)
218                         );
219         } while ((new_state != state) && (retry <= SMI_TRIES));
220 
221         /* enable IRQs */
222         local_irq_restore(flags);
223 
224         if (new_state == state)
225                 dprintk("change to %u MHz succeeded after %u tries "
226                         "with result %u\n",
227                         (speedstep_freqs[new_state].frequency / 1000),
228                         retry, result);
229         else
230                 printk(KERN_ERR "cpufreq: change to state %u "
231                         "failed with new_state %u and result %u\n",
232                         state, new_state, result);
233 
234         return;
235 }
236 
237 
238 /**
239  * speedstep_target - set a new CPUFreq policy
240  * @policy: new policy
241  * @target_freq: new freq
242  * @relation:
243  *
244  * Sets a new CPUFreq policy/freq.
245  */
246 static int speedstep_target(struct cpufreq_policy *policy,
247                         unsigned int target_freq, unsigned int relation)
248 {
249         unsigned int newstate = 0;
250         struct cpufreq_freqs freqs;
251 
252         if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
253                                 target_freq, relation, &newstate))
254                 return -EINVAL;
255 
256         freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
257         freqs.new = speedstep_freqs[newstate].frequency;
258         freqs.cpu = 0; /* speedstep.c is UP only driver */
259 
260         if (freqs.old == freqs.new)
261                 return 0;
262 
263         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
264         speedstep_set_state(newstate);
265         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
266 
267         return 0;
268 }
269 
270 
271 /**
272  * speedstep_verify - verifies a new CPUFreq policy
273  * @policy: new policy
274  *
275  * Limit must be within speedstep_low_freq and speedstep_high_freq, with
276  * at least one border included.
277  */
278 static int speedstep_verify(struct cpufreq_policy *policy)
279 {
280         return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
281 }
282 
283 
284 static int speedstep_cpu_init(struct cpufreq_policy *policy)
285 {
286         int result;
287         unsigned int speed, state;
288         unsigned int *low, *high;
289 
290         /* capability check */
291         if (policy->cpu != 0)
292                 return -ENODEV;
293 
294         result = speedstep_smi_ownership();
295         if (result) {
296                 dprintk("fails in aquiring ownership of a SMI interface.\n");
297                 return -EINVAL;
298         }
299 
300         /* detect low and high frequency */
301         low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
302         high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
303 
304         result = speedstep_smi_get_freqs(low, high);
305         if (result) {
306                 /* fall back to speedstep_lib.c dection mechanism:
307                  * try both states out */
308                 dprintk("could not detect low and high frequencies "
309                                 "by SMI call.\n");
310                 result = speedstep_get_freqs(speedstep_processor,
311                                 low, high,
312                                 NULL,
313                                 &speedstep_set_state);
314 
315                 if (result) {
316                         dprintk("could not detect two different speeds"
317                                         " -- aborting.\n");
318                         return result;
319                 } else
320                         dprintk("workaround worked.\n");
321         }
322 
323         /* get current speed setting */
324         state = speedstep_get_state();
325         speed = speedstep_freqs[state].frequency;
326 
327         dprintk("currently at %s speed setting - %i MHz\n",
328                 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
329                 ? "low" : "high",
330                 (speed / 1000));
331 
332         /* cpuinfo and default policy values */
333         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
334         policy->cur = speed;
335 
336         result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
337         if (result)
338                 return result;
339 
340         cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
341 
342         return 0;
343 }
344 
345 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
346 {
347         cpufreq_frequency_table_put_attr(policy->cpu);
348         return 0;
349 }
350 
351 static unsigned int speedstep_get(unsigned int cpu)
352 {
353         if (cpu)
354                 return -ENODEV;
355         return speedstep_get_frequency(speedstep_processor);
356 }
357 
358 
359 static int speedstep_resume(struct cpufreq_policy *policy)
360 {
361         int result = speedstep_smi_ownership();
362 
363         if (result)
364                 dprintk("fails in re-aquiring ownership of a SMI interface.\n");
365 
366         return result;
367 }
368 
369 static struct freq_attr *speedstep_attr[] = {
370         &cpufreq_freq_attr_scaling_available_freqs,
371         NULL,
372 };
373 
374 static struct cpufreq_driver speedstep_driver = {
375         .name           = "speedstep-smi",
376         .verify         = speedstep_verify,
377         .target         = speedstep_target,
378         .init           = speedstep_cpu_init,
379         .exit           = speedstep_cpu_exit,
380         .get            = speedstep_get,
381         .resume         = speedstep_resume,
382         .owner          = THIS_MODULE,
383         .attr           = speedstep_attr,
384 };
385 
386 /**
387  * speedstep_init - initializes the SpeedStep CPUFreq driver
388  *
389  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
390  * BIOS, -EINVAL on problems during initiatization, and zero on
391  * success.
392  */
393 static int __init speedstep_init(void)
394 {
395         speedstep_processor = speedstep_detect_processor();
396 
397         switch (speedstep_processor) {
398         case SPEEDSTEP_CPU_PIII_T:
399         case SPEEDSTEP_CPU_PIII_C:
400         case SPEEDSTEP_CPU_PIII_C_EARLY:
401                 break;
402         default:
403                 speedstep_processor = 0;
404         }
405 
406         if (!speedstep_processor) {
407                 dprintk("No supported Intel CPU detected.\n");
408                 return -ENODEV;
409         }
410 
411         dprintk("signature:0x%.8lx, command:0x%.8lx, "
412                 "event:0x%.8lx, perf_level:0x%.8lx.\n",
413                 ist_info.signature, ist_info.command,
414                 ist_info.event, ist_info.perf_level);
415 
416         /* Error if no IST-SMI BIOS or no PARM
417                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
418         if ((ist_info.signature !=  0x47534943) && (
419             (smi_port == 0) || (smi_cmd == 0)))
420                 return -ENODEV;
421 
422         if (smi_sig == 1)
423                 smi_sig = 0x47534943;
424         else
425                 smi_sig = ist_info.signature;
426 
427         /* setup smi_port from MODLULE_PARM or BIOS */
428         if ((smi_port > 0xff) || (smi_port < 0))
429                 return -EINVAL;
430         else if (smi_port == 0)
431                 smi_port = ist_info.command & 0xff;
432 
433         if ((smi_cmd > 0xff) || (smi_cmd < 0))
434                 return -EINVAL;
435         else if (smi_cmd == 0)
436                 smi_cmd = (ist_info.command >> 16) & 0xff;
437 
438         return cpufreq_register_driver(&speedstep_driver);
439 }
440 
441 
442 /**
443  * speedstep_exit - unregisters SpeedStep support
444  *
445  *   Unregisters SpeedStep support.
446  */
447 static void __exit speedstep_exit(void)
448 {
449         cpufreq_unregister_driver(&speedstep_driver);
450 }
451 
452 module_param(smi_port, int, 0444);
453 module_param(smi_cmd,  int, 0444);
454 module_param(smi_sig, uint, 0444);
455 
456 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
457                 "-- Intel's default setting is 0xb2");
458 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
459                 "-- Intel's default setting is 0x82");
460 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
461                 "SMI interface.");
462 
463 MODULE_AUTHOR("Hiroshi Miura");
464 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
465 MODULE_LICENSE("GPL");
466 
467 module_init(speedstep_init);
468 module_exit(speedstep_exit);
469 

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