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 | */ |
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(address: 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_set_state - set the SpeedStep state |
145 | * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH) |
146 | * |
147 | */ |
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 | */ |
221 | static int speedstep_target(struct cpufreq_policy *policy, unsigned int index) |
222 | { |
223 | speedstep_set_state(state: index); |
224 | |
225 | return 0; |
226 | } |
227 | |
228 | |
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(processor: speedstep_processor, |
255 | low_speed: low, high_speed: high, |
256 | NULL, |
257 | set_state: &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 | |
272 | static unsigned int speedstep_get(unsigned int cpu) |
273 | { |
274 | if (cpu) |
275 | return -ENODEV; |
276 | return speedstep_get_frequency(processor: speedstep_processor); |
277 | } |
278 | |
279 | |
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 | */ |
315 | static int __init speedstep_init(void) |
316 | { |
317 | if (!x86_match_cpu(match: 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(driver_data: &speedstep_driver); |
364 | } |
365 | |
366 | |
367 | /** |
368 | * speedstep_exit - unregisters SpeedStep support |
369 | * |
370 | * Unregisters SpeedStep support. |
371 | */ |
372 | static void __exit speedstep_exit(void) |
373 | { |
374 | cpufreq_unregister_driver(driver_data: &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 | |