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 #define pr_fmt(fmt) "cpufreq: " fmt
16
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/init.h>
21 #include <linux/cpufreq.h>
22 #include <linux/delay.h>
23 #include <linux/io.h>
24 #include <asm/ist.h>
25 #include <asm/cpu_device_id.h>
26
27 #include "speedstep-lib.h"
28
29 /* speedstep system management interface port/command.
30 *
31 * These parameters are got from IST-SMI BIOS call.
32 * If user gives it, these are used.
33 *
34 */
35 static int smi_port;
36 static int smi_cmd;
37 static unsigned int smi_sig;
38
39 /* info about the processor */
40 static enum speedstep_processor speedstep_processor;
41
42 /*
43 * There are only two frequency states for each processor. Values
44 * are in kHz for the time being.
45 */
46 static struct cpufreq_frequency_table speedstep_freqs[] = {
47 {0, SPEEDSTEP_HIGH, 0},
48 {0, SPEEDSTEP_LOW, 0},
49 {0, 0, CPUFREQ_TABLE_END},
50 };
51
52 #define GET_SPEEDSTEP_OWNER 0
53 #define GET_SPEEDSTEP_STATE 1
54 #define SET_SPEEDSTEP_STATE 2
55 #define GET_SPEEDSTEP_FREQS 4
56
57 /* how often shall the SMI call be tried if it failed, e.g. because
58 * of DMA activity going on? */
59 #define SMI_TRIES 5
60
61 /**
62 * speedstep_smi_ownership
63 */
speedstep_smi_ownership(void)64 static int speedstep_smi_ownership(void)
65 {
66 u32 command, result, magic, dummy;
67 u32 function = GET_SPEEDSTEP_OWNER;
68 unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
69
70 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
71 magic = virt_to_phys(magic_data);
72
73 pr_debug("trying to obtain ownership with command %x at port %x\n",
74 command, smi_port);
75
76 __asm__ __volatile__(
77 "push %%ebp\n"
78 "out %%al, (%%dx)\n"
79 "pop %%ebp\n"
80 : "=D" (result),
81 "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
82 "=S" (dummy)
83 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
84 "D" (0), "S" (magic)
85 : "memory"
86 );
87
88 pr_debug("result is %x\n", result);
89
90 return result;
91 }
92
93 /**
94 * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
95 * @low: the low frequency value is placed here
96 * @high: the high frequency value is placed here
97 *
98 * Only available on later SpeedStep-enabled systems, returns false results or
99 * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
100 * shows that the latter occurs if !(ist_info.event & 0xFFFF).
101 */
speedstep_smi_get_freqs(unsigned int * low,unsigned int * high)102 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
103 {
104 u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
105 u32 state = 0;
106 u32 function = GET_SPEEDSTEP_FREQS;
107
108 if (!(ist_info.event & 0xFFFF)) {
109 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
110 return -ENODEV;
111 }
112
113 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
114
115 pr_debug("trying to determine frequencies with command %x at port %x\n",
116 command, smi_port);
117
118 __asm__ __volatile__(
119 "push %%ebp\n"
120 "out %%al, (%%dx)\n"
121 "pop %%ebp"
122 : "=a" (result),
123 "=b" (high_mhz),
124 "=c" (low_mhz),
125 "=d" (state), "=D" (edi), "=S" (dummy)
126 : "a" (command),
127 "b" (function),
128 "c" (state),
129 "d" (smi_port), "S" (0), "D" (0)
130 );
131
132 pr_debug("result %x, low_freq %u, high_freq %u\n",
133 result, low_mhz, high_mhz);
134
135 /* abort if results are obviously incorrect... */
136 if ((high_mhz + low_mhz) < 600)
137 return -EINVAL;
138
139 *high = high_mhz * 1000;
140 *low = low_mhz * 1000;
141
142 return result;
143 }
144
145 /**
146 * speedstep_set_state - set the SpeedStep state
147 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
148 *
149 */
speedstep_set_state(unsigned int state)150 static void speedstep_set_state(unsigned int state)
151 {
152 unsigned int result = 0, command, new_state, dummy;
153 unsigned long flags;
154 unsigned int function = SET_SPEEDSTEP_STATE;
155 unsigned int retry = 0;
156
157 if (state > 0x1)
158 return;
159
160 /* Disable IRQs */
161 preempt_disable();
162 local_irq_save(flags);
163
164 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
165
166 pr_debug("trying to set frequency to state %u "
167 "with command %x at port %x\n",
168 state, command, smi_port);
169
170 do {
171 if (retry) {
172 /*
173 * We need to enable interrupts, otherwise the blockage
174 * won't resolve.
175 *
176 * We disable preemption so that other processes don't
177 * run. If other processes were running, they could
178 * submit more DMA requests, making the blockage worse.
179 */
180 pr_debug("retry %u, previous result %u, waiting...\n",
181 retry, result);
182 local_irq_enable();
183 mdelay(retry * 50);
184 local_irq_disable();
185 }
186 retry++;
187 __asm__ __volatile__(
188 "push %%ebp\n"
189 "out %%al, (%%dx)\n"
190 "pop %%ebp"
191 : "=b" (new_state), "=D" (result),
192 "=c" (dummy), "=a" (dummy),
193 "=d" (dummy), "=S" (dummy)
194 : "a" (command), "b" (function), "c" (state),
195 "d" (smi_port), "S" (0), "D" (0)
196 );
197 } while ((new_state != state) && (retry <= SMI_TRIES));
198
199 /* enable IRQs */
200 local_irq_restore(flags);
201 preempt_enable();
202
203 if (new_state == state)
204 pr_debug("change to %u MHz succeeded after %u tries "
205 "with result %u\n",
206 (speedstep_freqs[new_state].frequency / 1000),
207 retry, result);
208 else
209 pr_err("change to state %u failed with new_state %u and result %u\n",
210 state, new_state, result);
211
212 return;
213 }
214
215
216 /**
217 * speedstep_target - set a new CPUFreq policy
218 * @policy: new policy
219 * @index: index of new freq
220 *
221 * Sets a new CPUFreq policy/freq.
222 */
speedstep_target(struct cpufreq_policy * policy,unsigned int index)223 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
224 {
225 speedstep_set_state(index);
226
227 return 0;
228 }
229
230
speedstep_cpu_init(struct cpufreq_policy * policy)231 static int speedstep_cpu_init(struct cpufreq_policy *policy)
232 {
233 int result;
234 unsigned int *low, *high;
235
236 /* capability check */
237 if (policy->cpu != 0)
238 return -ENODEV;
239
240 result = speedstep_smi_ownership();
241 if (result) {
242 pr_debug("fails in acquiring ownership of a SMI interface.\n");
243 return -EINVAL;
244 }
245
246 /* detect low and high frequency */
247 low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
248 high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
249
250 result = speedstep_smi_get_freqs(low, high);
251 if (result) {
252 /* fall back to speedstep_lib.c dection mechanism:
253 * try both states out */
254 pr_debug("could not detect low and high frequencies "
255 "by SMI call.\n");
256 result = speedstep_get_freqs(speedstep_processor,
257 low, high,
258 NULL,
259 &speedstep_set_state);
260
261 if (result) {
262 pr_debug("could not detect two different speeds"
263 " -- aborting.\n");
264 return result;
265 } else
266 pr_debug("workaround worked.\n");
267 }
268
269 policy->freq_table = speedstep_freqs;
270
271 return 0;
272 }
273
speedstep_get(unsigned int cpu)274 static unsigned int speedstep_get(unsigned int cpu)
275 {
276 if (cpu)
277 return -ENODEV;
278 return speedstep_get_frequency(speedstep_processor);
279 }
280
281
speedstep_resume(struct cpufreq_policy * policy)282 static int speedstep_resume(struct cpufreq_policy *policy)
283 {
284 int result = speedstep_smi_ownership();
285
286 if (result)
287 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
288
289 return result;
290 }
291
292 static struct cpufreq_driver speedstep_driver = {
293 .name = "speedstep-smi",
294 .flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
295 .verify = cpufreq_generic_frequency_table_verify,
296 .target_index = speedstep_target,
297 .init = speedstep_cpu_init,
298 .get = speedstep_get,
299 .resume = speedstep_resume,
300 .attr = cpufreq_generic_attr,
301 };
302
303 static const struct x86_cpu_id ss_smi_ids[] = {
304 { X86_VENDOR_INTEL, 6, 0xb, },
305 { X86_VENDOR_INTEL, 6, 0x8, },
306 { X86_VENDOR_INTEL, 15, 2 },
307 {}
308 };
309 #if 0
310 /* Not auto loaded currently */
311 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
312 #endif
313
314 /**
315 * speedstep_init - initializes the SpeedStep CPUFreq driver
316 *
317 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
318 * BIOS, -EINVAL on problems during initiatization, and zero on
319 * success.
320 */
speedstep_init(void)321 static int __init speedstep_init(void)
322 {
323 if (!x86_match_cpu(ss_smi_ids))
324 return -ENODEV;
325
326 speedstep_processor = speedstep_detect_processor();
327
328 switch (speedstep_processor) {
329 case SPEEDSTEP_CPU_PIII_T:
330 case SPEEDSTEP_CPU_PIII_C:
331 case SPEEDSTEP_CPU_PIII_C_EARLY:
332 break;
333 default:
334 speedstep_processor = 0;
335 }
336
337 if (!speedstep_processor) {
338 pr_debug("No supported Intel CPU detected.\n");
339 return -ENODEV;
340 }
341
342 pr_debug("signature:0x%.8x, command:0x%.8x, "
343 "event:0x%.8x, perf_level:0x%.8x.\n",
344 ist_info.signature, ist_info.command,
345 ist_info.event, ist_info.perf_level);
346
347 /* Error if no IST-SMI BIOS or no PARM
348 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
349 if ((ist_info.signature != 0x47534943) && (
350 (smi_port == 0) || (smi_cmd == 0)))
351 return -ENODEV;
352
353 if (smi_sig == 1)
354 smi_sig = 0x47534943;
355 else
356 smi_sig = ist_info.signature;
357
358 /* setup smi_port from MODLULE_PARM or BIOS */
359 if ((smi_port > 0xff) || (smi_port < 0))
360 return -EINVAL;
361 else if (smi_port == 0)
362 smi_port = ist_info.command & 0xff;
363
364 if ((smi_cmd > 0xff) || (smi_cmd < 0))
365 return -EINVAL;
366 else if (smi_cmd == 0)
367 smi_cmd = (ist_info.command >> 16) & 0xff;
368
369 return cpufreq_register_driver(&speedstep_driver);
370 }
371
372
373 /**
374 * speedstep_exit - unregisters SpeedStep support
375 *
376 * Unregisters SpeedStep support.
377 */
speedstep_exit(void)378 static void __exit speedstep_exit(void)
379 {
380 cpufreq_unregister_driver(&speedstep_driver);
381 }
382
383 module_param_hw(smi_port, int, ioport, 0444);
384 module_param(smi_cmd, int, 0444);
385 module_param(smi_sig, uint, 0444);
386
387 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
388 "-- Intel's default setting is 0xb2");
389 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
390 "-- Intel's default setting is 0x82");
391 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
392 "SMI interface.");
393
394 MODULE_AUTHOR("Hiroshi Miura");
395 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
396 MODULE_LICENSE("GPL");
397
398 module_init(speedstep_init);
399 module_exit(speedstep_exit);
400
