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 {0, SPEEDSTEP_HIGH, 0},
46 {0, SPEEDSTEP_LOW, 0},
47 {0, 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 */
speedstep_smi_ownership(void)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 */
speedstep_smi_get_freqs(unsigned int * low,unsigned int * high)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_set_state - set the SpeedStep state
145 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
146 *
147 */
speedstep_set_state(unsigned int state)148 static void speedstep_set_state(unsigned int state)
149 {
150 unsigned int result = 0, command, new_state, dummy;
151 unsigned long flags;
152 unsigned int function = SET_SPEEDSTEP_STATE;
153 unsigned int retry = 0;
154
155 if (state > 0x1)
156 return;
157
158 /* Disable IRQs */
159 preempt_disable();
160 local_irq_save(flags);
161
162 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
163
164 pr_debug("trying to set frequency to state %u "
165 "with command %x at port %x\n",
166 state, command, smi_port);
167
168 do {
169 if (retry) {
170 /*
171 * We need to enable interrupts, otherwise the blockage
172 * won't resolve.
173 *
174 * We disable preemption so that other processes don't
175 * run. If other processes were running, they could
176 * submit more DMA requests, making the blockage worse.
177 */
178 pr_debug("retry %u, previous result %u, waiting...\n",
179 retry, result);
180 local_irq_enable();
181 mdelay(retry * 50);
182 local_irq_disable();
183 }
184 retry++;
185 __asm__ __volatile__(
186 "push %%ebp\n"
187 "out %%al, (%%dx)\n"
188 "pop %%ebp"
189 : "=b" (new_state), "=D" (result),
190 "=c" (dummy), "=a" (dummy),
191 "=d" (dummy), "=S" (dummy)
192 : "a" (command), "b" (function), "c" (state),
193 "d" (smi_port), "S" (0), "D" (0)
194 );
195 } while ((new_state != state) && (retry <= SMI_TRIES));
196
197 /* enable IRQs */
198 local_irq_restore(flags);
199 preempt_enable();
200
201 if (new_state == state)
202 pr_debug("change to %u MHz succeeded after %u tries "
203 "with result %u\n",
204 (speedstep_freqs[new_state].frequency / 1000),
205 retry, result);
206 else
207 printk(KERN_ERR "cpufreq: change to state %u "
208 "failed with new_state %u and result %u\n",
209 state, new_state, result);
210
211 return;
212 }
213
214
215 /**
216 * speedstep_target - set a new CPUFreq policy
217 * @policy: new policy
218 * @index: index of new freq
219 *
220 * Sets a new CPUFreq policy/freq.
221 */
speedstep_target(struct cpufreq_policy * policy,unsigned int index)222 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
223 {
224 speedstep_set_state(index);
225
226 return 0;
227 }
228
229
speedstep_cpu_init(struct cpufreq_policy * policy)230 static int speedstep_cpu_init(struct cpufreq_policy *policy)
231 {
232 int result;
233 unsigned int *low, *high;
234
235 /* capability check */
236 if (policy->cpu != 0)
237 return -ENODEV;
238
239 result = speedstep_smi_ownership();
240 if (result) {
241 pr_debug("fails in acquiring ownership of a SMI interface.\n");
242 return -EINVAL;
243 }
244
245 /* detect low and high frequency */
246 low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
247 high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
248
249 result = speedstep_smi_get_freqs(low, high);
250 if (result) {
251 /* fall back to speedstep_lib.c dection mechanism:
252 * try both states out */
253 pr_debug("could not detect low and high frequencies "
254 "by SMI call.\n");
255 result = speedstep_get_freqs(speedstep_processor,
256 low, high,
257 NULL,
258 &speedstep_set_state);
259
260 if (result) {
261 pr_debug("could not detect two different speeds"
262 " -- aborting.\n");
263 return result;
264 } else
265 pr_debug("workaround worked.\n");
266 }
267
268 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
269 return cpufreq_table_validate_and_show(policy, speedstep_freqs);
270 }
271
speedstep_get(unsigned int cpu)272 static unsigned int speedstep_get(unsigned int cpu)
273 {
274 if (cpu)
275 return -ENODEV;
276 return speedstep_get_frequency(speedstep_processor);
277 }
278
279
speedstep_resume(struct cpufreq_policy * policy)280 static int speedstep_resume(struct cpufreq_policy *policy)
281 {
282 int result = speedstep_smi_ownership();
283
284 if (result)
285 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
286
287 return result;
288 }
289
290 static struct cpufreq_driver speedstep_driver = {
291 .name = "speedstep-smi",
292 .verify = cpufreq_generic_frequency_table_verify,
293 .target_index = speedstep_target,
294 .init = speedstep_cpu_init,
295 .get = speedstep_get,
296 .resume = speedstep_resume,
297 .attr = cpufreq_generic_attr,
298 };
299
300 static const struct x86_cpu_id ss_smi_ids[] = {
301 { X86_VENDOR_INTEL, 6, 0xb, },
302 { X86_VENDOR_INTEL, 6, 0x8, },
303 { X86_VENDOR_INTEL, 15, 2 },
304 {}
305 };
306 #if 0
307 /* Not auto loaded currently */
308 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
309 #endif
310
311 /**
312 * speedstep_init - initializes the SpeedStep CPUFreq driver
313 *
314 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
315 * BIOS, -EINVAL on problems during initiatization, and zero on
316 * success.
317 */
speedstep_init(void)318 static int __init speedstep_init(void)
319 {
320 if (!x86_match_cpu(ss_smi_ids))
321 return -ENODEV;
322
323 speedstep_processor = speedstep_detect_processor();
324
325 switch (speedstep_processor) {
326 case SPEEDSTEP_CPU_PIII_T:
327 case SPEEDSTEP_CPU_PIII_C:
328 case SPEEDSTEP_CPU_PIII_C_EARLY:
329 break;
330 default:
331 speedstep_processor = 0;
332 }
333
334 if (!speedstep_processor) {
335 pr_debug("No supported Intel CPU detected.\n");
336 return -ENODEV;
337 }
338
339 pr_debug("signature:0x%.8x, command:0x%.8x, "
340 "event:0x%.8x, perf_level:0x%.8x.\n",
341 ist_info.signature, ist_info.command,
342 ist_info.event, ist_info.perf_level);
343
344 /* Error if no IST-SMI BIOS or no PARM
345 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
346 if ((ist_info.signature != 0x47534943) && (
347 (smi_port == 0) || (smi_cmd == 0)))
348 return -ENODEV;
349
350 if (smi_sig == 1)
351 smi_sig = 0x47534943;
352 else
353 smi_sig = ist_info.signature;
354
355 /* setup smi_port from MODLULE_PARM or BIOS */
356 if ((smi_port > 0xff) || (smi_port < 0))
357 return -EINVAL;
358 else if (smi_port == 0)
359 smi_port = ist_info.command & 0xff;
360
361 if ((smi_cmd > 0xff) || (smi_cmd < 0))
362 return -EINVAL;
363 else if (smi_cmd == 0)
364 smi_cmd = (ist_info.command >> 16) & 0xff;
365
366 return cpufreq_register_driver(&speedstep_driver);
367 }
368
369
370 /**
371 * speedstep_exit - unregisters SpeedStep support
372 *
373 * Unregisters SpeedStep support.
374 */
speedstep_exit(void)375 static void __exit speedstep_exit(void)
376 {
377 cpufreq_unregister_driver(&speedstep_driver);
378 }
379
380 module_param(smi_port, int, 0444);
381 module_param(smi_cmd, int, 0444);
382 module_param(smi_sig, uint, 0444);
383
384 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
385 "-- Intel's default setting is 0xb2");
386 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
387 "-- Intel's default setting is 0x82");
388 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
389 "SMI interface.");
390
391 MODULE_AUTHOR("Hiroshi Miura");
392 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
393 MODULE_LICENSE("GPL");
394
395 module_init(speedstep_init);
396 module_exit(speedstep_exit);
397