GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / cpufreq / e_powersaver.c
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 */
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
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
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
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
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
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 = &centaur->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 = &centaur->freq_table[0];
359
360         return 0;
361 }
362
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
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
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);