Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Based on documentation provided by Dave Jones. Thanks!
4 *
5 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/cpufreq.h>
14#include <linux/ioport.h>
15#include <linux/slab.h>
16#include <linux/timex.h>
17#include <linux/io.h>
18#include <linux/delay.h>
19
20#include <asm/cpu_device_id.h>
21#include <asm/msr.h>
22#include <asm/tsc.h>
23
24#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
25#include <linux/acpi.h>
26#include <acpi/processor.h>
27#endif
28
29#define EPS_BRAND_C7M 0
30#define EPS_BRAND_C7 1
31#define EPS_BRAND_EDEN 2
32#define EPS_BRAND_C3 3
33#define EPS_BRAND_C7D 4
34
35struct eps_cpu_data {
36 u32 fsb;
37#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
38 u32 bios_limit;
39#endif
40 struct cpufreq_frequency_table freq_table[];
41};
42
43static struct eps_cpu_data *eps_cpu[NR_CPUS];
44
45/* Module parameters */
46static int freq_failsafe_off;
47static int voltage_failsafe_off;
48static int set_max_voltage;
49
50#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
51static int ignore_acpi_limit;
52
53static struct acpi_processor_performance *eps_acpi_cpu_perf;
54
55/* Minimum necessary to get acpi_processor_get_bios_limit() working */
56static int eps_acpi_init(void)
57{
58 eps_acpi_cpu_perf = kzalloc_obj(*eps_acpi_cpu_perf);
59 if (!eps_acpi_cpu_perf)
60 return -ENOMEM;
61
62 if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
63 GFP_KERNEL)) {
64 kfree(eps_acpi_cpu_perf);
65 eps_acpi_cpu_perf = NULL;
66 return -ENOMEM;
67 }
68
69 if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
70 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
71 kfree(eps_acpi_cpu_perf);
72 eps_acpi_cpu_perf = NULL;
73 return -EIO;
74 }
75 return 0;
76}
77
78static int eps_acpi_exit(struct cpufreq_policy *policy)
79{
80 if (eps_acpi_cpu_perf) {
81 acpi_processor_unregister_performance(0);
82 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
83 kfree(eps_acpi_cpu_perf);
84 eps_acpi_cpu_perf = NULL;
85 }
86 return 0;
87}
88#endif
89
90static unsigned int eps_get(unsigned int cpu)
91{
92 struct eps_cpu_data *centaur;
93 u32 lo, hi;
94
95 if (cpu)
96 return 0;
97 centaur = eps_cpu[cpu];
98 if (centaur == NULL)
99 return 0;
100
101 /* Return current frequency */
102 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
103 return centaur->fsb * ((lo >> 8) & 0xff);
104}
105
106static int eps_set_state(struct eps_cpu_data *centaur,
107 struct cpufreq_policy *policy,
108 u32 dest_state)
109{
110 u32 lo, hi;
111 int i;
112
113 /* Wait while CPU is busy */
114 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
115 i = 0;
116 while (lo & ((1 << 16) | (1 << 17))) {
117 udelay(16);
118 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
119 i++;
120 if (unlikely(i > 64)) {
121 return -ENODEV;
122 }
123 }
124 /* Set new multiplier and voltage */
125 wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
126 /* Wait until transition end */
127 i = 0;
128 do {
129 udelay(16);
130 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
131 i++;
132 if (unlikely(i > 64)) {
133 return -ENODEV;
134 }
135 } while (lo & ((1 << 16) | (1 << 17)));
136
137#ifdef DEBUG
138 {
139 u8 current_multiplier, current_voltage;
140
141 /* Print voltage and multiplier */
142 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
143 current_voltage = lo & 0xff;
144 pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
145 current_multiplier = (lo >> 8) & 0xff;
146 pr_info("Current multiplier = %d\n", current_multiplier);
147 }
148#endif
149 return 0;
150}
151
152static int eps_target(struct cpufreq_policy *policy, unsigned int index)
153{
154 struct eps_cpu_data *centaur;
155 unsigned int cpu = policy->cpu;
156 unsigned int dest_state;
157 int ret;
158
159 if (unlikely(eps_cpu[cpu] == NULL))
160 return -ENODEV;
161 centaur = eps_cpu[cpu];
162
163 /* Make frequency transition */
164 dest_state = centaur->freq_table[index].driver_data & 0xffff;
165 ret = eps_set_state(centaur, policy, dest_state);
166 if (ret)
167 pr_err("Timeout!\n");
168 return ret;
169}
170
171static int eps_cpu_init(struct cpufreq_policy *policy)
172{
173 unsigned int i;
174 u32 lo, hi;
175 u64 val;
176 u8 current_multiplier, current_voltage;
177 u8 max_multiplier, max_voltage;
178 u8 min_multiplier, min_voltage;
179 u8 brand = 0;
180 u32 fsb;
181 struct eps_cpu_data *centaur;
182 struct cpuinfo_x86 *c = &cpu_data(0);
183 struct cpufreq_frequency_table *f_table;
184 int k, step, voltage;
185 int states;
186#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
187 unsigned int limit;
188#endif
189
190 if (policy->cpu != 0)
191 return -ENODEV;
192
193 /* Check brand */
194 pr_info("Detected VIA ");
195
196 switch (c->x86_model) {
197 case 10:
198 rdmsr(0x1153, lo, hi);
199 brand = (((lo >> 2) ^ lo) >> 18) & 3;
200 pr_cont("Model A ");
201 break;
202 case 13:
203 rdmsr(0x1154, lo, hi);
204 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
205 pr_cont("Model D ");
206 break;
207 }
208
209 switch (brand) {
210 case EPS_BRAND_C7M:
211 pr_cont("C7-M\n");
212 break;
213 case EPS_BRAND_C7:
214 pr_cont("C7\n");
215 break;
216 case EPS_BRAND_EDEN:
217 pr_cont("Eden\n");
218 break;
219 case EPS_BRAND_C7D:
220 pr_cont("C7-D\n");
221 break;
222 case EPS_BRAND_C3:
223 pr_cont("C3\n");
224 return -ENODEV;
225 }
226 /* Enable Enhanced PowerSaver */
227 rdmsrq(MSR_IA32_MISC_ENABLE, val);
228 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
229 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
230 wrmsrq(MSR_IA32_MISC_ENABLE, val);
231 /* Can be locked at 0 */
232 rdmsrq(MSR_IA32_MISC_ENABLE, val);
233 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
234 pr_info("Can't enable Enhanced PowerSaver\n");
235 return -ENODEV;
236 }
237 }
238
239 /* Print voltage and multiplier */
240 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
241 current_voltage = lo & 0xff;
242 pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
243 current_multiplier = (lo >> 8) & 0xff;
244 pr_info("Current multiplier = %d\n", current_multiplier);
245
246 /* Print limits */
247 max_voltage = hi & 0xff;
248 pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
249 max_multiplier = (hi >> 8) & 0xff;
250 pr_info("Highest multiplier = %d\n", max_multiplier);
251 min_voltage = (hi >> 16) & 0xff;
252 pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
253 min_multiplier = (hi >> 24) & 0xff;
254 pr_info("Lowest multiplier = %d\n", min_multiplier);
255
256 /* Sanity checks */
257 if (current_multiplier == 0 || max_multiplier == 0
258 || min_multiplier == 0)
259 return -EINVAL;
260 if (current_multiplier > max_multiplier
261 || max_multiplier <= min_multiplier)
262 return -EINVAL;
263 if (current_voltage > 0x1f || max_voltage > 0x1f)
264 return -EINVAL;
265 if (max_voltage < min_voltage
266 || current_voltage < min_voltage
267 || current_voltage > max_voltage)
268 return -EINVAL;
269
270 /* Check for systems using underclocked CPU */
271 if (!freq_failsafe_off && max_multiplier != current_multiplier) {
272 pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
273 pr_info("You can use freq_failsafe_off option to disable this check.\n");
274 return -EINVAL;
275 }
276 if (!voltage_failsafe_off && max_voltage != current_voltage) {
277 pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
278 pr_info("You can use voltage_failsafe_off option to disable this check.\n");
279 return -EINVAL;
280 }
281
282 /* Calc FSB speed */
283 fsb = cpu_khz / current_multiplier;
284
285#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
286 /* Check for ACPI processor speed limit */
287 if (!ignore_acpi_limit && !eps_acpi_init()) {
288 if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
289 pr_info("ACPI limit %u.%uGHz\n",
290 limit/1000000,
291 (limit%1000000)/10000);
292 eps_acpi_exit(policy);
293 /* Check if max_multiplier is in BIOS limits */
294 if (limit && max_multiplier * fsb > limit) {
295 pr_info("Aborting\n");
296 return -EINVAL;
297 }
298 }
299 }
300#endif
301
302 /* Allow user to set lower maximum voltage then that reported
303 * by processor */
304 if (brand == EPS_BRAND_C7M && set_max_voltage) {
305 u32 v;
306
307 /* Change mV to something hardware can use */
308 v = (set_max_voltage - 700) / 16;
309 /* Check if voltage is within limits */
310 if (v >= min_voltage && v <= max_voltage) {
311 pr_info("Setting %dmV as maximum\n", v * 16 + 700);
312 max_voltage = v;
313 }
314 }
315
316 /* Calc number of p-states supported */
317 if (brand == EPS_BRAND_C7M)
318 states = max_multiplier - min_multiplier + 1;
319 else
320 states = 2;
321
322 /* Allocate private data and frequency table for current cpu */
323 centaur = kzalloc_flex(*centaur, freq_table, states + 1);
324 if (!centaur)
325 return -ENOMEM;
326 eps_cpu[0] = centaur;
327
328 /* Copy basic values */
329 centaur->fsb = fsb;
330#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
331 centaur->bios_limit = limit;
332#endif
333
334 /* Fill frequency and MSR value table */
335 f_table = ¢aur->freq_table[0];
336 if (brand != EPS_BRAND_C7M) {
337 f_table[0].frequency = fsb * min_multiplier;
338 f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
339 f_table[1].frequency = fsb * max_multiplier;
340 f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
341 f_table[2].frequency = CPUFREQ_TABLE_END;
342 } else {
343 k = 0;
344 step = ((max_voltage - min_voltage) * 256)
345 / (max_multiplier - min_multiplier);
346 for (i = min_multiplier; i <= max_multiplier; i++) {
347 voltage = (k * step) / 256 + min_voltage;
348 f_table[k].frequency = fsb * i;
349 f_table[k].driver_data = (i << 8) | voltage;
350 k++;
351 }
352 f_table[k].frequency = CPUFREQ_TABLE_END;
353 }
354
355 policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
356 policy->freq_table = ¢aur->freq_table[0];
357
358 return 0;
359}
360
361static void eps_cpu_exit(struct cpufreq_policy *policy)
362{
363 unsigned int cpu = policy->cpu;
364
365 /* Bye */
366 kfree(eps_cpu[cpu]);
367 eps_cpu[cpu] = NULL;
368}
369
370static struct cpufreq_driver eps_driver = {
371 .verify = cpufreq_generic_frequency_table_verify,
372 .target_index = eps_target,
373 .init = eps_cpu_init,
374 .exit = eps_cpu_exit,
375 .get = eps_get,
376 .name = "e_powersaver",
377};
378
379
380/* This driver will work only on Centaur C7 processors with
381 * Enhanced SpeedStep/PowerSaver registers */
382static const struct x86_cpu_id eps_cpu_id[] = {
383 X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_EST, NULL),
384 {}
385};
386MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
387
388static int __init eps_init(void)
389{
390 if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
391 return -ENODEV;
392 if (cpufreq_register_driver(&eps_driver))
393 return -EINVAL;
394 return 0;
395}
396
397static void __exit eps_exit(void)
398{
399 cpufreq_unregister_driver(&eps_driver);
400}
401
402/* Allow user to overclock his machine or to change frequency to higher after
403 * unloading module */
404module_param(freq_failsafe_off, int, 0644);
405MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
406module_param(voltage_failsafe_off, int, 0644);
407MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
408#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
409module_param(ignore_acpi_limit, int, 0644);
410MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
411#endif
412module_param(set_max_voltage, int, 0644);
413MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
414
415MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
416MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
417MODULE_LICENSE("GPL");
418
419module_init(eps_init);
420module_exit(eps_exit);