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
35 struct 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
43 static struct eps_cpu_data *eps_cpu[NR_CPUS];
44
45 /* Module parameters */
46 static int freq_failsafe_off;
47 static int voltage_failsafe_off;
48 static int set_max_voltage;
49
50 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
51 static int ignore_acpi_limit;
52
53 static struct acpi_processor_performance *eps_acpi_cpu_perf;
54
55 /* Minimum necessary to get acpi_processor_get_bios_limit() working */
eps_acpi_init(void)56 static int eps_acpi_init(void)
57 {
58 eps_acpi_cpu_perf = kzalloc(sizeof(*eps_acpi_cpu_perf),
59 GFP_KERNEL);
60 if (!eps_acpi_cpu_perf)
61 return -ENOMEM;
62
63 if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
64 GFP_KERNEL)) {
65 kfree(eps_acpi_cpu_perf);
66 eps_acpi_cpu_perf = NULL;
67 return -ENOMEM;
68 }
69
70 if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
71 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
72 kfree(eps_acpi_cpu_perf);
73 eps_acpi_cpu_perf = NULL;
74 return -EIO;
75 }
76 return 0;
77 }
78
eps_acpi_exit(struct cpufreq_policy * policy)79 static int eps_acpi_exit(struct cpufreq_policy *policy)
80 {
81 if (eps_acpi_cpu_perf) {
82 acpi_processor_unregister_performance(0);
83 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
84 kfree(eps_acpi_cpu_perf);
85 eps_acpi_cpu_perf = NULL;
86 }
87 return 0;
88 }
89 #endif
90
eps_get(unsigned int cpu)91 static unsigned int eps_get(unsigned int cpu)
92 {
93 struct eps_cpu_data *centaur;
94 u32 lo, hi;
95
96 if (cpu)
97 return 0;
98 centaur = eps_cpu[cpu];
99 if (centaur == NULL)
100 return 0;
101
102 /* Return current frequency */
103 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
104 return centaur->fsb * ((lo >> 8) & 0xff);
105 }
106
eps_set_state(struct eps_cpu_data * centaur,struct cpufreq_policy * policy,u32 dest_state)107 static int eps_set_state(struct eps_cpu_data *centaur,
108 struct cpufreq_policy *policy,
109 u32 dest_state)
110 {
111 u32 lo, hi;
112 int i;
113
114 /* Wait while CPU is busy */
115 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
116 i = 0;
117 while (lo & ((1 << 16) | (1 << 17))) {
118 udelay(16);
119 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
120 i++;
121 if (unlikely(i > 64)) {
122 return -ENODEV;
123 }
124 }
125 /* Set new multiplier and voltage */
126 wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
127 /* Wait until transition end */
128 i = 0;
129 do {
130 udelay(16);
131 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
132 i++;
133 if (unlikely(i > 64)) {
134 return -ENODEV;
135 }
136 } while (lo & ((1 << 16) | (1 << 17)));
137
138 #ifdef DEBUG
139 {
140 u8 current_multiplier, current_voltage;
141
142 /* Print voltage and multiplier */
143 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
144 current_voltage = lo & 0xff;
145 pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
146 current_multiplier = (lo >> 8) & 0xff;
147 pr_info("Current multiplier = %d\n", current_multiplier);
148 }
149 #endif
150 return 0;
151 }
152
eps_target(struct cpufreq_policy * policy,unsigned int index)153 static int eps_target(struct cpufreq_policy *policy, unsigned int index)
154 {
155 struct eps_cpu_data *centaur;
156 unsigned int cpu = policy->cpu;
157 unsigned int dest_state;
158 int ret;
159
160 if (unlikely(eps_cpu[cpu] == NULL))
161 return -ENODEV;
162 centaur = eps_cpu[cpu];
163
164 /* Make frequency transition */
165 dest_state = centaur->freq_table[index].driver_data & 0xffff;
166 ret = eps_set_state(centaur, policy, dest_state);
167 if (ret)
168 pr_err("Timeout!\n");
169 return ret;
170 }
171
eps_cpu_init(struct cpufreq_policy * policy)172 static int eps_cpu_init(struct cpufreq_policy *policy)
173 {
174 unsigned int i;
175 u32 lo, hi;
176 u64 val;
177 u8 current_multiplier, current_voltage;
178 u8 max_multiplier, max_voltage;
179 u8 min_multiplier, min_voltage;
180 u8 brand = 0;
181 u32 fsb;
182 struct eps_cpu_data *centaur;
183 struct cpuinfo_x86 *c = &cpu_data(0);
184 struct cpufreq_frequency_table *f_table;
185 int k, step, voltage;
186 int states;
187 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
188 unsigned int limit;
189 #endif
190
191 if (policy->cpu != 0)
192 return -ENODEV;
193
194 /* Check brand */
195 pr_info("Detected VIA ");
196
197 switch (c->x86_model) {
198 case 10:
199 rdmsr(0x1153, lo, hi);
200 brand = (((lo >> 2) ^ lo) >> 18) & 3;
201 pr_cont("Model A ");
202 break;
203 case 13:
204 rdmsr(0x1154, lo, hi);
205 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
206 pr_cont("Model D ");
207 break;
208 }
209
210 switch (brand) {
211 case EPS_BRAND_C7M:
212 pr_cont("C7-M\n");
213 break;
214 case EPS_BRAND_C7:
215 pr_cont("C7\n");
216 break;
217 case EPS_BRAND_EDEN:
218 pr_cont("Eden\n");
219 break;
220 case EPS_BRAND_C7D:
221 pr_cont("C7-D\n");
222 break;
223 case EPS_BRAND_C3:
224 pr_cont("C3\n");
225 return -ENODEV;
226 }
227 /* Enable Enhanced PowerSaver */
228 rdmsrl(MSR_IA32_MISC_ENABLE, val);
229 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
230 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
231 wrmsrl(MSR_IA32_MISC_ENABLE, val);
232 /* Can be locked at 0 */
233 rdmsrl(MSR_IA32_MISC_ENABLE, val);
234 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
235 pr_info("Can't enable Enhanced PowerSaver\n");
236 return -ENODEV;
237 }
238 }
239
240 /* Print voltage and multiplier */
241 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
242 current_voltage = lo & 0xff;
243 pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
244 current_multiplier = (lo >> 8) & 0xff;
245 pr_info("Current multiplier = %d\n", current_multiplier);
246
247 /* Print limits */
248 max_voltage = hi & 0xff;
249 pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
250 max_multiplier = (hi >> 8) & 0xff;
251 pr_info("Highest multiplier = %d\n", max_multiplier);
252 min_voltage = (hi >> 16) & 0xff;
253 pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
254 min_multiplier = (hi >> 24) & 0xff;
255 pr_info("Lowest multiplier = %d\n", min_multiplier);
256
257 /* Sanity checks */
258 if (current_multiplier == 0 || max_multiplier == 0
259 || min_multiplier == 0)
260 return -EINVAL;
261 if (current_multiplier > max_multiplier
262 || max_multiplier <= min_multiplier)
263 return -EINVAL;
264 if (current_voltage > 0x1f || max_voltage > 0x1f)
265 return -EINVAL;
266 if (max_voltage < min_voltage
267 || current_voltage < min_voltage
268 || current_voltage > max_voltage)
269 return -EINVAL;
270
271 /* Check for systems using underclocked CPU */
272 if (!freq_failsafe_off && max_multiplier != current_multiplier) {
273 pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
274 pr_info("You can use freq_failsafe_off option to disable this check.\n");
275 return -EINVAL;
276 }
277 if (!voltage_failsafe_off && max_voltage != current_voltage) {
278 pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
279 pr_info("You can use voltage_failsafe_off option to disable this check.\n");
280 return -EINVAL;
281 }
282
283 /* Calc FSB speed */
284 fsb = cpu_khz / current_multiplier;
285
286 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
287 /* Check for ACPI processor speed limit */
288 if (!ignore_acpi_limit && !eps_acpi_init()) {
289 if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
290 pr_info("ACPI limit %u.%uGHz\n",
291 limit/1000000,
292 (limit%1000000)/10000);
293 eps_acpi_exit(policy);
294 /* Check if max_multiplier is in BIOS limits */
295 if (limit && max_multiplier * fsb > limit) {
296 pr_info("Aborting\n");
297 return -EINVAL;
298 }
299 }
300 }
301 #endif
302
303 /* Allow user to set lower maximum voltage then that reported
304 * by processor */
305 if (brand == EPS_BRAND_C7M && set_max_voltage) {
306 u32 v;
307
308 /* Change mV to something hardware can use */
309 v = (set_max_voltage - 700) / 16;
310 /* Check if voltage is within limits */
311 if (v >= min_voltage && v <= max_voltage) {
312 pr_info("Setting %dmV as maximum\n", v * 16 + 700);
313 max_voltage = v;
314 }
315 }
316
317 /* Calc number of p-states supported */
318 if (brand == EPS_BRAND_C7M)
319 states = max_multiplier - min_multiplier + 1;
320 else
321 states = 2;
322
323 /* Allocate private data and frequency table for current cpu */
324 centaur = kzalloc(struct_size(centaur, freq_table, states + 1),
325 GFP_KERNEL);
326 if (!centaur)
327 return -ENOMEM;
328 eps_cpu[0] = centaur;
329
330 /* Copy basic values */
331 centaur->fsb = fsb;
332 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
333 centaur->bios_limit = limit;
334 #endif
335
336 /* Fill frequency and MSR value table */
337 f_table = ¢aur->freq_table[0];
338 if (brand != EPS_BRAND_C7M) {
339 f_table[0].frequency = fsb * min_multiplier;
340 f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
341 f_table[1].frequency = fsb * max_multiplier;
342 f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
343 f_table[2].frequency = CPUFREQ_TABLE_END;
344 } else {
345 k = 0;
346 step = ((max_voltage - min_voltage) * 256)
347 / (max_multiplier - min_multiplier);
348 for (i = min_multiplier; i <= max_multiplier; i++) {
349 voltage = (k * step) / 256 + min_voltage;
350 f_table[k].frequency = fsb * i;
351 f_table[k].driver_data = (i << 8) | voltage;
352 k++;
353 }
354 f_table[k].frequency = CPUFREQ_TABLE_END;
355 }
356
357 policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
358 policy->freq_table = ¢aur->freq_table[0];
359
360 return 0;
361 }
362
eps_cpu_exit(struct cpufreq_policy * policy)363 static int eps_cpu_exit(struct cpufreq_policy *policy)
364 {
365 unsigned int cpu = policy->cpu;
366
367 /* Bye */
368 kfree(eps_cpu[cpu]);
369 eps_cpu[cpu] = NULL;
370 return 0;
371 }
372
373 static struct cpufreq_driver eps_driver = {
374 .verify = cpufreq_generic_frequency_table_verify,
375 .target_index = eps_target,
376 .init = eps_cpu_init,
377 .exit = eps_cpu_exit,
378 .get = eps_get,
379 .name = "e_powersaver",
380 .attr = cpufreq_generic_attr,
381 };
382
383
384 /* This driver will work only on Centaur C7 processors with
385 * Enhanced SpeedStep/PowerSaver registers */
386 static const struct x86_cpu_id eps_cpu_id[] = {
387 X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_EST, NULL),
388 {}
389 };
390 MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
391
eps_init(void)392 static int __init eps_init(void)
393 {
394 if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
395 return -ENODEV;
396 if (cpufreq_register_driver(&eps_driver))
397 return -EINVAL;
398 return 0;
399 }
400
eps_exit(void)401 static void __exit eps_exit(void)
402 {
403 cpufreq_unregister_driver(&eps_driver);
404 }
405
406 /* Allow user to overclock his machine or to change frequency to higher after
407 * unloading module */
408 module_param(freq_failsafe_off, int, 0644);
409 MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
410 module_param(voltage_failsafe_off, int, 0644);
411 MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
412 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
413 module_param(ignore_acpi_limit, int, 0644);
414 MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
415 #endif
416 module_param(set_max_voltage, int, 0644);
417 MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
418
419 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
420 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
421 MODULE_LICENSE("GPL");
422
423 module_init(eps_init);
424 module_exit(eps_exit);
425