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/delay.h>
21 #include <linux/io.h>
22 #include <asm/ist.h>
23 #include <asm/cpu_device_id.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 enum speedstep_processor 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 /**
60  * speedstep_smi_ownership
61  */
62 static int speedstep_smi_ownership(void)
63 {
64 	u32 command, result, magic, dummy;
65 	u32 function = GET_SPEEDSTEP_OWNER;
66 	unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
67 
68 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
69 	magic = virt_to_phys(magic_data);
70 
71 	pr_debug("trying to obtain ownership with command %x at port %x\n",
72 			command, smi_port);
73 
74 	__asm__ __volatile__(
75 		"push %%ebp\n"
76 		"out %%al, (%%dx)\n"
77 		"pop %%ebp\n"
78 		: "=D" (result),
79 		  "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
80 		  "=S" (dummy)
81 		: "a" (command), "b" (function), "c" (0), "d" (smi_port),
82 		  "D" (0), "S" (magic)
83 		: "memory"
84 	);
85 
86 	pr_debug("result is %x\n", result);
87 
88 	return result;
89 }
90 
91 /**
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
95  *
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).
99  */
100 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
101 {
102 	u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
103 	u32 state = 0;
104 	u32 function = GET_SPEEDSTEP_FREQS;
105 
106 	if (!(ist_info.event & 0xFFFF)) {
107 		pr_debug("bug #1422 -- can't read freqs from BIOS\n");
108 		return -ENODEV;
109 	}
110 
111 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
112 
113 	pr_debug("trying to determine frequencies with command %x at port %x\n",
114 			command, smi_port);
115 
116 	__asm__ __volatile__(
117 		"push %%ebp\n"
118 		"out %%al, (%%dx)\n"
119 		"pop %%ebp"
120 		: "=a" (result),
121 		  "=b" (high_mhz),
122 		  "=c" (low_mhz),
123 		  "=d" (state), "=D" (edi), "=S" (dummy)
124 		: "a" (command),
125 		  "b" (function),
126 		  "c" (state),
127 		  "d" (smi_port), "S" (0), "D" (0)
128 	);
129 
130 	pr_debug("result %x, low_freq %u, high_freq %u\n",
131 			result, low_mhz, high_mhz);
132 
133 	/* abort if results are obviously incorrect... */
134 	if ((high_mhz + low_mhz) < 600)
135 		return -EINVAL;
136 
137 	*high = high_mhz * 1000;
138 	*low  = low_mhz  * 1000;
139 
140 	return result;
141 }
142 
143 /**
144  * speedstep_get_state - set the SpeedStep state
145  * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
146  *
147  */
148 static int speedstep_get_state(void)
149 {
150 	u32 function = GET_SPEEDSTEP_STATE;
151 	u32 result, state, edi, command, dummy;
152 
153 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
154 
155 	pr_debug("trying to determine current setting with command %x "
156 		"at port %x\n", command, smi_port);
157 
158 	__asm__ __volatile__(
159 		"push %%ebp\n"
160 		"out %%al, (%%dx)\n"
161 		"pop %%ebp\n"
162 		: "=a" (result),
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)
167 	);
168 
169 	pr_debug("state is %x, result is %x\n", state, result);
170 
171 	return state & 1;
172 }
173 
174 
175 /**
176  * speedstep_set_state - set the SpeedStep state
177  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
178  *
179  */
180 static void speedstep_set_state(unsigned int state)
181 {
182 	unsigned int result = 0, command, new_state, dummy;
183 	unsigned long flags;
184 	unsigned int function = SET_SPEEDSTEP_STATE;
185 	unsigned int retry = 0;
186 
187 	if (state > 0x1)
188 		return;
189 
190 	/* Disable IRQs */
191 	local_irq_save(flags);
192 
193 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
194 
195 	pr_debug("trying to set frequency to state %u "
196 		"with command %x at port %x\n",
197 		state, command, smi_port);
198 
199 	do {
200 		if (retry) {
201 			pr_debug("retry %u, previous result %u, waiting...\n",
202 					retry, result);
203 			mdelay(retry * 50);
204 		}
205 		retry++;
206 		__asm__ __volatile__(
207 			"push %%ebp\n"
208 			"out %%al, (%%dx)\n"
209 			"pop %%ebp"
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)
215 			);
216 	} while ((new_state != state) && (retry <= SMI_TRIES));
217 
218 	/* enable IRQs */
219 	local_irq_restore(flags);
220 
221 	if (new_state == state)
222 		pr_debug("change to %u MHz succeeded after %u tries "
223 			"with result %u\n",
224 			(speedstep_freqs[new_state].frequency / 1000),
225 			retry, result);
226 	else
227 		printk(KERN_ERR "cpufreq: change to state %u "
228 			"failed with new_state %u and result %u\n",
229 			state, new_state, result);
230 
231 	return;
232 }
233 
234 
235 /**
236  * speedstep_target - set a new CPUFreq policy
237  * @policy: new policy
238  * @target_freq: new freq
239  * @relation:
240  *
241  * Sets a new CPUFreq policy/freq.
242  */
243 static int speedstep_target(struct cpufreq_policy *policy,
244 			unsigned int target_freq, unsigned int relation)
245 {
246 	unsigned int newstate = 0;
247 	struct cpufreq_freqs freqs;
248 
249 	if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
250 				target_freq, relation, &newstate))
251 		return -EINVAL;
252 
253 	freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
254 	freqs.new = speedstep_freqs[newstate].frequency;
255 
256 	if (freqs.old == freqs.new)
257 		return 0;
258 
259 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
260 	speedstep_set_state(newstate);
261 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
262 
263 	return 0;
264 }
265 
266 
267 /**
268  * speedstep_verify - verifies a new CPUFreq policy
269  * @policy: new policy
270  *
271  * Limit must be within speedstep_low_freq and speedstep_high_freq, with
272  * at least one border included.
273  */
274 static int speedstep_verify(struct cpufreq_policy *policy)
275 {
276 	return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
277 }
278 
279 
280 static int speedstep_cpu_init(struct cpufreq_policy *policy)
281 {
282 	int result;
283 	unsigned int speed, state;
284 	unsigned int *low, *high;
285 
286 	/* capability check */
287 	if (policy->cpu != 0)
288 		return -ENODEV;
289 
290 	result = speedstep_smi_ownership();
291 	if (result) {
292 		pr_debug("fails in acquiring ownership of a SMI interface.\n");
293 		return -EINVAL;
294 	}
295 
296 	/* detect low and high frequency */
297 	low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
298 	high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
299 
300 	result = speedstep_smi_get_freqs(low, high);
301 	if (result) {
302 		/* fall back to speedstep_lib.c dection mechanism:
303 		 * try both states out */
304 		pr_debug("could not detect low and high frequencies "
305 				"by SMI call.\n");
306 		result = speedstep_get_freqs(speedstep_processor,
307 				low, high,
308 				NULL,
309 				&speedstep_set_state);
310 
311 		if (result) {
312 			pr_debug("could not detect two different speeds"
313 					" -- aborting.\n");
314 			return result;
315 		} else
316 			pr_debug("workaround worked.\n");
317 	}
318 
319 	/* get current speed setting */
320 	state = speedstep_get_state();
321 	speed = speedstep_freqs[state].frequency;
322 
323 	pr_debug("currently at %s speed setting - %i MHz\n",
324 		(speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
325 		? "low" : "high",
326 		(speed / 1000));
327 
328 	/* cpuinfo and default policy values */
329 	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
330 	policy->cur = speed;
331 
332 	result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
333 	if (result)
334 		return result;
335 
336 	cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
337 
338 	return 0;
339 }
340 
341 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
342 {
343 	cpufreq_frequency_table_put_attr(policy->cpu);
344 	return 0;
345 }
346 
347 static unsigned int speedstep_get(unsigned int cpu)
348 {
349 	if (cpu)
350 		return -ENODEV;
351 	return speedstep_get_frequency(speedstep_processor);
352 }
353 
354 
355 static int speedstep_resume(struct cpufreq_policy *policy)
356 {
357 	int result = speedstep_smi_ownership();
358 
359 	if (result)
360 		pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
361 
362 	return result;
363 }
364 
365 static struct freq_attr *speedstep_attr[] = {
366 	&cpufreq_freq_attr_scaling_available_freqs,
367 	NULL,
368 };
369 
370 static struct cpufreq_driver speedstep_driver = {
371 	.name		= "speedstep-smi",
372 	.verify		= speedstep_verify,
373 	.target		= speedstep_target,
374 	.init		= speedstep_cpu_init,
375 	.exit		= speedstep_cpu_exit,
376 	.get		= speedstep_get,
377 	.resume		= speedstep_resume,
378 	.owner		= THIS_MODULE,
379 	.attr		= speedstep_attr,
380 };
381 
382 static const struct x86_cpu_id ss_smi_ids[] = {
383 	{ X86_VENDOR_INTEL, 6, 0xb, },
384 	{ X86_VENDOR_INTEL, 6, 0x8, },
385 	{ X86_VENDOR_INTEL, 15, 2 },
386 	{}
387 };
388 #if 0
389 /* Not auto loaded currently */
390 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
391 #endif
392 
393 /**
394  * speedstep_init - initializes the SpeedStep CPUFreq driver
395  *
396  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
397  * BIOS, -EINVAL on problems during initiatization, and zero on
398  * success.
399  */
400 static int __init speedstep_init(void)
401 {
402 	if (!x86_match_cpu(ss_smi_ids))
403 		return -ENODEV;
404 
405 	speedstep_processor = speedstep_detect_processor();
406 
407 	switch (speedstep_processor) {
408 	case SPEEDSTEP_CPU_PIII_T:
409 	case SPEEDSTEP_CPU_PIII_C:
410 	case SPEEDSTEP_CPU_PIII_C_EARLY:
411 		break;
412 	default:
413 		speedstep_processor = 0;
414 	}
415 
416 	if (!speedstep_processor) {
417 		pr_debug("No supported Intel CPU detected.\n");
418 		return -ENODEV;
419 	}
420 
421 	pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
422 		"event:0x%.8ulx, perf_level:0x%.8ulx.\n",
423 		ist_info.signature, ist_info.command,
424 		ist_info.event, ist_info.perf_level);
425 
426 	/* Error if no IST-SMI BIOS or no PARM
427 		 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
428 	if ((ist_info.signature !=  0x47534943) && (
429 	    (smi_port == 0) || (smi_cmd == 0)))
430 		return -ENODEV;
431 
432 	if (smi_sig == 1)
433 		smi_sig = 0x47534943;
434 	else
435 		smi_sig = ist_info.signature;
436 
437 	/* setup smi_port from MODLULE_PARM or BIOS */
438 	if ((smi_port > 0xff) || (smi_port < 0))
439 		return -EINVAL;
440 	else if (smi_port == 0)
441 		smi_port = ist_info.command & 0xff;
442 
443 	if ((smi_cmd > 0xff) || (smi_cmd < 0))
444 		return -EINVAL;
445 	else if (smi_cmd == 0)
446 		smi_cmd = (ist_info.command >> 16) & 0xff;
447 
448 	return cpufreq_register_driver(&speedstep_driver);
449 }
450 
451 
452 /**
453  * speedstep_exit - unregisters SpeedStep support
454  *
455  *   Unregisters SpeedStep support.
456  */
457 static void __exit speedstep_exit(void)
458 {
459 	cpufreq_unregister_driver(&speedstep_driver);
460 }
461 
462 module_param(smi_port, int, 0444);
463 module_param(smi_cmd,  int, 0444);
464 module_param(smi_sig, uint, 0444);
465 
466 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
467 		"-- Intel's default setting is 0xb2");
468 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
469 		"-- Intel's default setting is 0x82");
470 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
471 		"SMI interface.");
472 
473 MODULE_AUTHOR("Hiroshi Miura");
474 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
475 MODULE_LICENSE("GPL");
476 
477 module_init(speedstep_init);
478 module_exit(speedstep_exit);
479