1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
4 *
5 * Library for common functions for Intel SpeedStep v.1 and v.2 support
6 *
7 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
8 */
9
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/moduleparam.h>
15 #include <linux/init.h>
16 #include <linux/cpufreq.h>
17
18 #include <asm/msr.h>
19 #include <asm/tsc.h>
20 #include "speedstep-lib.h"
21
22 #define PFX "speedstep-lib: "
23
24 #ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK
25 static int relaxed_check;
26 #else
27 #define relaxed_check 0
28 #endif
29
30 /*********************************************************************
31 * GET PROCESSOR CORE SPEED IN KHZ *
32 *********************************************************************/
33
pentium3_get_frequency(enum speedstep_processor processor)34 static unsigned int pentium3_get_frequency(enum speedstep_processor processor)
35 {
36 /* See table 14 of p3_ds.pdf and table 22 of 29834003.pdf */
37 static const struct {
38 unsigned int ratio; /* Frequency Multiplier (x10) */
39 u8 bitmap; /* power on configuration bits
40 [27, 25:22] (in MSR 0x2a) */
41 } msr_decode_mult[] = {
42 { 30, 0x01 },
43 { 35, 0x05 },
44 { 40, 0x02 },
45 { 45, 0x06 },
46 { 50, 0x00 },
47 { 55, 0x04 },
48 { 60, 0x0b },
49 { 65, 0x0f },
50 { 70, 0x09 },
51 { 75, 0x0d },
52 { 80, 0x0a },
53 { 85, 0x26 },
54 { 90, 0x20 },
55 { 100, 0x2b },
56 { 0, 0xff } /* error or unknown value */
57 };
58
59 /* PIII(-M) FSB settings: see table b1-b of 24547206.pdf */
60 static const struct {
61 unsigned int value; /* Front Side Bus speed in MHz */
62 u8 bitmap; /* power on configuration bits [18: 19]
63 (in MSR 0x2a) */
64 } msr_decode_fsb[] = {
65 { 66, 0x0 },
66 { 100, 0x2 },
67 { 133, 0x1 },
68 { 0, 0xff}
69 };
70
71 u32 msr_lo, msr_tmp;
72 int i = 0, j = 0;
73
74 /* read MSR 0x2a - we only need the low 32 bits */
75 rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
76 pr_debug("P3 - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
77 msr_tmp = msr_lo;
78
79 /* decode the FSB */
80 msr_tmp &= 0x00c0000;
81 msr_tmp >>= 18;
82 while (msr_tmp != msr_decode_fsb[i].bitmap) {
83 if (msr_decode_fsb[i].bitmap == 0xff)
84 return 0;
85 i++;
86 }
87
88 /* decode the multiplier */
89 if (processor == SPEEDSTEP_CPU_PIII_C_EARLY) {
90 pr_debug("workaround for early PIIIs\n");
91 msr_lo &= 0x03c00000;
92 } else
93 msr_lo &= 0x0bc00000;
94 msr_lo >>= 22;
95 while (msr_lo != msr_decode_mult[j].bitmap) {
96 if (msr_decode_mult[j].bitmap == 0xff)
97 return 0;
98 j++;
99 }
100
101 pr_debug("speed is %u\n",
102 (msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100));
103
104 return msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100;
105 }
106
107
pentiumM_get_frequency(void)108 static unsigned int pentiumM_get_frequency(void)
109 {
110 u32 msr_lo, msr_tmp;
111
112 rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
113 pr_debug("PM - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
114
115 /* see table B-2 of 24547212.pdf */
116 if (msr_lo & 0x00040000) {
117 printk(KERN_DEBUG PFX "PM - invalid FSB: 0x%x 0x%x\n",
118 msr_lo, msr_tmp);
119 return 0;
120 }
121
122 msr_tmp = (msr_lo >> 22) & 0x1f;
123 pr_debug("bits 22-26 are 0x%x, speed is %u\n",
124 msr_tmp, (msr_tmp * 100 * 1000));
125
126 return msr_tmp * 100 * 1000;
127 }
128
pentium_core_get_frequency(void)129 static unsigned int pentium_core_get_frequency(void)
130 {
131 u32 fsb = 0;
132 u32 msr_lo, msr_tmp;
133 int ret;
134
135 rdmsr(MSR_FSB_FREQ, msr_lo, msr_tmp);
136 /* see table B-2 of 25366920.pdf */
137 switch (msr_lo & 0x07) {
138 case 5:
139 fsb = 100000;
140 break;
141 case 1:
142 fsb = 133333;
143 break;
144 case 3:
145 fsb = 166667;
146 break;
147 case 2:
148 fsb = 200000;
149 break;
150 case 0:
151 fsb = 266667;
152 break;
153 case 4:
154 fsb = 333333;
155 break;
156 default:
157 pr_err("PCORE - MSR_FSB_FREQ undefined value\n");
158 }
159
160 rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
161 pr_debug("PCORE - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n",
162 msr_lo, msr_tmp);
163
164 msr_tmp = (msr_lo >> 22) & 0x1f;
165 pr_debug("bits 22-26 are 0x%x, speed is %u\n",
166 msr_tmp, (msr_tmp * fsb));
167
168 ret = (msr_tmp * fsb);
169 return ret;
170 }
171
172
pentium4_get_frequency(void)173 static unsigned int pentium4_get_frequency(void)
174 {
175 struct cpuinfo_x86 *c = &boot_cpu_data;
176 u32 msr_lo, msr_hi, mult;
177 unsigned int fsb = 0;
178 unsigned int ret;
179 u8 fsb_code;
180
181 /* Pentium 4 Model 0 and 1 do not have the Core Clock Frequency
182 * to System Bus Frequency Ratio Field in the Processor Frequency
183 * Configuration Register of the MSR. Therefore the current
184 * frequency cannot be calculated and has to be measured.
185 */
186 if (c->x86_model < 2)
187 return cpu_khz;
188
189 rdmsr(0x2c, msr_lo, msr_hi);
190
191 pr_debug("P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi);
192
193 /* decode the FSB: see IA-32 Intel (C) Architecture Software
194 * Developer's Manual, Volume 3: System Prgramming Guide,
195 * revision #12 in Table B-1: MSRs in the Pentium 4 and
196 * Intel Xeon Processors, on page B-4 and B-5.
197 */
198 fsb_code = (msr_lo >> 16) & 0x7;
199 switch (fsb_code) {
200 case 0:
201 fsb = 100 * 1000;
202 break;
203 case 1:
204 fsb = 13333 * 10;
205 break;
206 case 2:
207 fsb = 200 * 1000;
208 break;
209 }
210
211 if (!fsb)
212 printk(KERN_DEBUG PFX "couldn't detect FSB speed. "
213 "Please send an e-mail to <linux@brodo.de>\n");
214
215 /* Multiplier. */
216 mult = msr_lo >> 24;
217
218 pr_debug("P4 - FSB %u kHz; Multiplier %u; Speed %u kHz\n",
219 fsb, mult, (fsb * mult));
220
221 ret = (fsb * mult);
222 return ret;
223 }
224
225
226 /* Warning: may get called from smp_call_function_single. */
speedstep_get_frequency(enum speedstep_processor processor)227 unsigned int speedstep_get_frequency(enum speedstep_processor processor)
228 {
229 switch (processor) {
230 case SPEEDSTEP_CPU_PCORE:
231 return pentium_core_get_frequency();
232 case SPEEDSTEP_CPU_PM:
233 return pentiumM_get_frequency();
234 case SPEEDSTEP_CPU_P4D:
235 case SPEEDSTEP_CPU_P4M:
236 return pentium4_get_frequency();
237 case SPEEDSTEP_CPU_PIII_T:
238 case SPEEDSTEP_CPU_PIII_C:
239 case SPEEDSTEP_CPU_PIII_C_EARLY:
240 return pentium3_get_frequency(processor);
241 default:
242 return 0;
243 }
244 return 0;
245 }
246 EXPORT_SYMBOL_GPL(speedstep_get_frequency);
247
248
249 /*********************************************************************
250 * DETECT SPEEDSTEP-CAPABLE PROCESSOR *
251 *********************************************************************/
252
253 /* Keep in sync with the x86_cpu_id tables in the different modules */
speedstep_detect_processor(void)254 enum speedstep_processor speedstep_detect_processor(void)
255 {
256 struct cpuinfo_x86 *c = &cpu_data(0);
257 u32 ebx, msr_lo, msr_hi;
258
259 pr_debug("x86: %x, model: %x\n", c->x86, c->x86_model);
260
261 if ((c->x86_vendor != X86_VENDOR_INTEL) ||
262 ((c->x86 != 6) && (c->x86 != 0xF)))
263 return 0;
264
265 if (c->x86 == 0xF) {
266 /* Intel Mobile Pentium 4-M
267 * or Intel Mobile Pentium 4 with 533 MHz FSB */
268 if (c->x86_model != 2)
269 return 0;
270
271 ebx = cpuid_ebx(0x00000001);
272 ebx &= 0x000000FF;
273
274 pr_debug("ebx value is %x, x86_stepping is %x\n", ebx, c->x86_stepping);
275
276 switch (c->x86_stepping) {
277 case 4:
278 /*
279 * B-stepping [M-P4-M]
280 * sample has ebx = 0x0f, production has 0x0e.
281 */
282 if ((ebx == 0x0e) || (ebx == 0x0f))
283 return SPEEDSTEP_CPU_P4M;
284 break;
285 case 7:
286 /*
287 * C-stepping [M-P4-M]
288 * needs to have ebx=0x0e, else it's a celeron:
289 * cf. 25130917.pdf / page 7, footnote 5 even
290 * though 25072120.pdf / page 7 doesn't say
291 * samples are only of B-stepping...
292 */
293 if (ebx == 0x0e)
294 return SPEEDSTEP_CPU_P4M;
295 break;
296 case 9:
297 /*
298 * D-stepping [M-P4-M or M-P4/533]
299 *
300 * this is totally strange: CPUID 0x0F29 is
301 * used by M-P4-M, M-P4/533 and(!) Celeron CPUs.
302 * The latter need to be sorted out as they don't
303 * support speedstep.
304 * Celerons with CPUID 0x0F29 may have either
305 * ebx=0x8 or 0xf -- 25130917.pdf doesn't say anything
306 * specific.
307 * M-P4-Ms may have either ebx=0xe or 0xf [see above]
308 * M-P4/533 have either ebx=0xe or 0xf. [25317607.pdf]
309 * also, M-P4M HTs have ebx=0x8, too
310 * For now, they are distinguished by the model_id
311 * string
312 */
313 if ((ebx == 0x0e) ||
314 (strstr(c->x86_model_id,
315 "Mobile Intel(R) Pentium(R) 4") != NULL))
316 return SPEEDSTEP_CPU_P4M;
317 break;
318 default:
319 break;
320 }
321 return 0;
322 }
323
324 switch (c->x86_model) {
325 case 0x0B: /* Intel PIII [Tualatin] */
326 /* cpuid_ebx(1) is 0x04 for desktop PIII,
327 * 0x06 for mobile PIII-M */
328 ebx = cpuid_ebx(0x00000001);
329 pr_debug("ebx is %x\n", ebx);
330
331 ebx &= 0x000000FF;
332
333 if (ebx != 0x06)
334 return 0;
335
336 /* So far all PIII-M processors support SpeedStep. See
337 * Intel's 24540640.pdf of June 2003
338 */
339 return SPEEDSTEP_CPU_PIII_T;
340
341 case 0x08: /* Intel PIII [Coppermine] */
342
343 /* all mobile PIII Coppermines have FSB 100 MHz
344 * ==> sort out a few desktop PIIIs. */
345 rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_hi);
346 pr_debug("Coppermine: MSR_IA32_EBL_CR_POWERON is 0x%x, 0x%x\n",
347 msr_lo, msr_hi);
348 msr_lo &= 0x00c0000;
349 if (msr_lo != 0x0080000)
350 return 0;
351
352 /*
353 * If the processor is a mobile version,
354 * platform ID has bit 50 set
355 * it has SpeedStep technology if either
356 * bit 56 or 57 is set
357 */
358 rdmsr(MSR_IA32_PLATFORM_ID, msr_lo, msr_hi);
359 pr_debug("Coppermine: MSR_IA32_PLATFORM ID is 0x%x, 0x%x\n",
360 msr_lo, msr_hi);
361 if ((msr_hi & (1<<18)) &&
362 (relaxed_check ? 1 : (msr_hi & (3<<24)))) {
363 if (c->x86_stepping == 0x01) {
364 pr_debug("early PIII version\n");
365 return SPEEDSTEP_CPU_PIII_C_EARLY;
366 } else
367 return SPEEDSTEP_CPU_PIII_C;
368 }
369 fallthrough;
370 default:
371 return 0;
372 }
373 }
374 EXPORT_SYMBOL_GPL(speedstep_detect_processor);
375
376
377 /*********************************************************************
378 * DETECT SPEEDSTEP SPEEDS *
379 *********************************************************************/
380
speedstep_get_freqs(enum speedstep_processor processor,unsigned int * low_speed,unsigned int * high_speed,unsigned int * transition_latency,void (* set_state)(unsigned int state))381 unsigned int speedstep_get_freqs(enum speedstep_processor processor,
382 unsigned int *low_speed,
383 unsigned int *high_speed,
384 unsigned int *transition_latency,
385 void (*set_state) (unsigned int state))
386 {
387 unsigned int prev_speed;
388 unsigned int ret = 0;
389 unsigned long flags;
390 ktime_t tv1, tv2;
391
392 if ((!processor) || (!low_speed) || (!high_speed) || (!set_state))
393 return -EINVAL;
394
395 pr_debug("trying to determine both speeds\n");
396
397 /* get current speed */
398 prev_speed = speedstep_get_frequency(processor);
399 if (!prev_speed)
400 return -EIO;
401
402 pr_debug("previous speed is %u\n", prev_speed);
403
404 preempt_disable();
405 local_irq_save(flags);
406
407 /* switch to low state */
408 set_state(SPEEDSTEP_LOW);
409 *low_speed = speedstep_get_frequency(processor);
410 if (!*low_speed) {
411 ret = -EIO;
412 goto out;
413 }
414
415 pr_debug("low speed is %u\n", *low_speed);
416
417 /* start latency measurement */
418 if (transition_latency)
419 tv1 = ktime_get();
420
421 /* switch to high state */
422 set_state(SPEEDSTEP_HIGH);
423
424 /* end latency measurement */
425 if (transition_latency)
426 tv2 = ktime_get();
427
428 *high_speed = speedstep_get_frequency(processor);
429 if (!*high_speed) {
430 ret = -EIO;
431 goto out;
432 }
433
434 pr_debug("high speed is %u\n", *high_speed);
435
436 if (*low_speed == *high_speed) {
437 ret = -ENODEV;
438 goto out;
439 }
440
441 /* switch to previous state, if necessary */
442 if (*high_speed != prev_speed)
443 set_state(SPEEDSTEP_LOW);
444
445 if (transition_latency) {
446 *transition_latency = ktime_to_us(ktime_sub(tv2, tv1));
447 pr_debug("transition latency is %u uSec\n", *transition_latency);
448
449 /* convert uSec to nSec and add 20% for safety reasons */
450 *transition_latency *= 1200;
451
452 /* check if the latency measurement is too high or too low
453 * and set it to a safe value (500uSec) in that case
454 */
455 if (*transition_latency > 10000000 ||
456 *transition_latency < 50000) {
457 pr_warn("frequency transition measured seems out of range (%u nSec), falling back to a safe one of %u nSec\n",
458 *transition_latency, 500000);
459 *transition_latency = 500000;
460 }
461 }
462
463 out:
464 local_irq_restore(flags);
465 preempt_enable();
466
467 return ret;
468 }
469 EXPORT_SYMBOL_GPL(speedstep_get_freqs);
470
471 #ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK
472 module_param(relaxed_check, int, 0444);
473 MODULE_PARM_DESC(relaxed_check,
474 "Don't do all checks for speedstep capability.");
475 #endif
476
477 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
478 MODULE_DESCRIPTION("Library for Intel SpeedStep 1 or 2 cpufreq drivers.");
479 MODULE_LICENSE("GPL");
480