1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Intel SpeedStep SMI driver.
4 *
5 * (C) 2003 Hiroshi Miura <miura@da-cha.org>
6 */
7
8
9 /*********************************************************************
10 * SPEEDSTEP - DEFINITIONS *
11 *********************************************************************/
12
13 #define pr_fmt(fmt) "cpufreq: " fmt
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 pr_err("change to state %u failed with new_state %u and result %u\n",
208 state, new_state, result);
209
210 return;
211 }
212
213
214 /**
215 * speedstep_target - set a new CPUFreq policy
216 * @policy: new policy
217 * @index: index of new freq
218 *
219 * Sets a new CPUFreq policy/freq.
220 */
speedstep_target(struct cpufreq_policy * policy,unsigned int index)221 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
222 {
223 speedstep_set_state(index);
224
225 return 0;
226 }
227
228
speedstep_cpu_init(struct cpufreq_policy * policy)229 static int speedstep_cpu_init(struct cpufreq_policy *policy)
230 {
231 int result;
232 unsigned int *low, *high;
233
234 /* capability check */
235 if (policy->cpu != 0)
236 return -ENODEV;
237
238 result = speedstep_smi_ownership();
239 if (result) {
240 pr_debug("fails in acquiring ownership of a SMI interface.\n");
241 return -EINVAL;
242 }
243
244 /* detect low and high frequency */
245 low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
246 high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
247
248 result = speedstep_smi_get_freqs(low, high);
249 if (result) {
250 /* fall back to speedstep_lib.c dection mechanism:
251 * try both states out */
252 pr_debug("could not detect low and high frequencies "
253 "by SMI call.\n");
254 result = speedstep_get_freqs(speedstep_processor,
255 low, high,
256 NULL,
257 &speedstep_set_state);
258
259 if (result) {
260 pr_debug("could not detect two different speeds"
261 " -- aborting.\n");
262 return result;
263 } else
264 pr_debug("workaround worked.\n");
265 }
266
267 policy->freq_table = speedstep_freqs;
268
269 return 0;
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 .flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
293 .verify = cpufreq_generic_frequency_table_verify,
294 .target_index = speedstep_target,
295 .init = speedstep_cpu_init,
296 .get = speedstep_get,
297 .resume = speedstep_resume,
298 .attr = cpufreq_generic_attr,
299 };
300
301 static const struct x86_cpu_id ss_smi_ids[] = {
302 X86_MATCH_VENDOR_FAM_MODEL(INTEL, 6, 0x8, 0),
303 X86_MATCH_VENDOR_FAM_MODEL(INTEL, 6, 0xb, 0),
304 X86_MATCH_VENDOR_FAM_MODEL(INTEL, 15, 0x2, 0),
305 {}
306 };
307
308 /**
309 * speedstep_init - initializes the SpeedStep CPUFreq driver
310 *
311 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
312 * BIOS, -EINVAL on problems during initiatization, and zero on
313 * success.
314 */
speedstep_init(void)315 static int __init speedstep_init(void)
316 {
317 if (!x86_match_cpu(ss_smi_ids))
318 return -ENODEV;
319
320 speedstep_processor = speedstep_detect_processor();
321
322 switch (speedstep_processor) {
323 case SPEEDSTEP_CPU_PIII_T:
324 case SPEEDSTEP_CPU_PIII_C:
325 case SPEEDSTEP_CPU_PIII_C_EARLY:
326 break;
327 default:
328 speedstep_processor = 0;
329 }
330
331 if (!speedstep_processor) {
332 pr_debug("No supported Intel CPU detected.\n");
333 return -ENODEV;
334 }
335
336 pr_debug("signature:0x%.8x, command:0x%.8x, "
337 "event:0x%.8x, perf_level:0x%.8x.\n",
338 ist_info.signature, ist_info.command,
339 ist_info.event, ist_info.perf_level);
340
341 /* Error if no IST-SMI BIOS or no PARM
342 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
343 if ((ist_info.signature != 0x47534943) && (
344 (smi_port == 0) || (smi_cmd == 0)))
345 return -ENODEV;
346
347 if (smi_sig == 1)
348 smi_sig = 0x47534943;
349 else
350 smi_sig = ist_info.signature;
351
352 /* setup smi_port from MODLULE_PARM or BIOS */
353 if ((smi_port > 0xff) || (smi_port < 0))
354 return -EINVAL;
355 else if (smi_port == 0)
356 smi_port = ist_info.command & 0xff;
357
358 if ((smi_cmd > 0xff) || (smi_cmd < 0))
359 return -EINVAL;
360 else if (smi_cmd == 0)
361 smi_cmd = (ist_info.command >> 16) & 0xff;
362
363 return cpufreq_register_driver(&speedstep_driver);
364 }
365
366
367 /**
368 * speedstep_exit - unregisters SpeedStep support
369 *
370 * Unregisters SpeedStep support.
371 */
speedstep_exit(void)372 static void __exit speedstep_exit(void)
373 {
374 cpufreq_unregister_driver(&speedstep_driver);
375 }
376
377 module_param_hw(smi_port, int, ioport, 0444);
378 module_param(smi_cmd, int, 0444);
379 module_param(smi_sig, uint, 0444);
380
381 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
382 "-- Intel's default setting is 0xb2");
383 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
384 "-- Intel's default setting is 0x82");
385 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
386 "SMI interface.");
387
388 MODULE_AUTHOR("Hiroshi Miura");
389 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
390 MODULE_LICENSE("GPL");
391
392 module_init(speedstep_init);
393 module_exit(speedstep_exit);
394