GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / cpufreq / longrun.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
4  *
5  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
6  */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/cpufreq.h>
12 #include <linux/timex.h>
13
14 #include <asm/msr.h>
15 #include <asm/processor.h>
16 #include <asm/cpu_device_id.h>
17
18 static struct cpufreq_driver    longrun_driver;
19
20 /**
21  * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
22  * values into per cent values. In TMTA microcode, the following is valid:
23  * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
24  */
25 static unsigned int longrun_low_freq, longrun_high_freq;
26
27
28 /**
29  * longrun_get_policy - get the current LongRun policy
30  * @policy: struct cpufreq_policy where current policy is written into
31  *
32  * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
33  * and MSR_TMTA_LONGRUN_CTRL
34  */
35 static void longrun_get_policy(struct cpufreq_policy *policy)
36 {
37         u32 msr_lo, msr_hi;
38
39         rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
40         pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi);
41         if (msr_lo & 0x01)
42                 policy->policy = CPUFREQ_POLICY_PERFORMANCE;
43         else
44                 policy->policy = CPUFREQ_POLICY_POWERSAVE;
45
46         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
47         pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
48         msr_lo &= 0x0000007F;
49         msr_hi &= 0x0000007F;
50
51         if (longrun_high_freq <= longrun_low_freq) {
52                 /* Assume degenerate Longrun table */
53                 policy->min = policy->max = longrun_high_freq;
54         } else {
55                 policy->min = longrun_low_freq + msr_lo *
56                         ((longrun_high_freq - longrun_low_freq) / 100);
57                 policy->max = longrun_low_freq + msr_hi *
58                         ((longrun_high_freq - longrun_low_freq) / 100);
59         }
60         policy->cpu = 0;
61 }
62
63
64 /**
65  * longrun_set_policy - sets a new CPUFreq policy
66  * @policy: new policy
67  *
68  * Sets a new CPUFreq policy on LongRun-capable processors. This function
69  * has to be called with cpufreq_driver locked.
70  */
71 static int longrun_set_policy(struct cpufreq_policy *policy)
72 {
73         u32 msr_lo, msr_hi;
74         u32 pctg_lo, pctg_hi;
75
76         if (!policy)
77                 return -EINVAL;
78
79         if (longrun_high_freq <= longrun_low_freq) {
80                 /* Assume degenerate Longrun table */
81                 pctg_lo = pctg_hi = 100;
82         } else {
83                 pctg_lo = (policy->min - longrun_low_freq) /
84                         ((longrun_high_freq - longrun_low_freq) / 100);
85                 pctg_hi = (policy->max - longrun_low_freq) /
86                         ((longrun_high_freq - longrun_low_freq) / 100);
87         }
88
89         if (pctg_hi > 100)
90                 pctg_hi = 100;
91         if (pctg_lo > pctg_hi)
92                 pctg_lo = pctg_hi;
93
94         /* performance or economy mode */
95         rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
96         msr_lo &= 0xFFFFFFFE;
97         switch (policy->policy) {
98         case CPUFREQ_POLICY_PERFORMANCE:
99                 msr_lo |= 0x00000001;
100                 break;
101         case CPUFREQ_POLICY_POWERSAVE:
102                 break;
103         }
104         wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
105
106         /* lower and upper boundary */
107         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
108         msr_lo &= 0xFFFFFF80;
109         msr_hi &= 0xFFFFFF80;
110         msr_lo |= pctg_lo;
111         msr_hi |= pctg_hi;
112         wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
113
114         return 0;
115 }
116
117
118 /**
119  * longrun_verify_poliy - verifies a new CPUFreq policy
120  * @policy: the policy to verify
121  *
122  * Validates a new CPUFreq policy. This function has to be called with
123  * cpufreq_driver locked.
124  */
125 static int longrun_verify_policy(struct cpufreq_policy_data *policy)
126 {
127         if (!policy)
128                 return -EINVAL;
129
130         policy->cpu = 0;
131         cpufreq_verify_within_cpu_limits(policy);
132
133         return 0;
134 }
135
136 static unsigned int longrun_get(unsigned int cpu)
137 {
138         u32 eax, ebx, ecx, edx;
139
140         if (cpu)
141                 return 0;
142
143         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
144         pr_debug("cpuid eax is %u\n", eax);
145
146         return eax * 1000;
147 }
148
149 /**
150  * longrun_determine_freqs - determines the lowest and highest possible core frequency
151  * @low_freq: an int to put the lowest frequency into
152  * @high_freq: an int to put the highest frequency into
153  *
154  * Determines the lowest and highest possible core frequencies on this CPU.
155  * This is necessary to calculate the performance percentage according to
156  * TMTA rules:
157  * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
158  */
159 static int longrun_determine_freqs(unsigned int *low_freq,
160                                                       unsigned int *high_freq)
161 {
162         u32 msr_lo, msr_hi;
163         u32 save_lo, save_hi;
164         u32 eax, ebx, ecx, edx;
165         u32 try_hi;
166         struct cpuinfo_x86 *c = &cpu_data(0);
167
168         if (!low_freq || !high_freq)
169                 return -EINVAL;
170
171         if (cpu_has(c, X86_FEATURE_LRTI)) {
172                 /* if the LongRun Table Interface is present, the
173                  * detection is a bit easier:
174                  * For minimum frequency, read out the maximum
175                  * level (msr_hi), write that into "currently
176                  * selected level", and read out the frequency.
177                  * For maximum frequency, read out level zero.
178                  */
179                 /* minimum */
180                 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
181                 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
182                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
183                 *low_freq = msr_lo * 1000; /* to kHz */
184
185                 /* maximum */
186                 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
187                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
188                 *high_freq = msr_lo * 1000; /* to kHz */
189
190                 pr_debug("longrun table interface told %u - %u kHz\n",
191                                 *low_freq, *high_freq);
192
193                 if (*low_freq > *high_freq)
194                         *low_freq = *high_freq;
195                 return 0;
196         }
197
198         /* set the upper border to the value determined during TSC init */
199         *high_freq = (cpu_khz / 1000);
200         *high_freq = *high_freq * 1000;
201         pr_debug("high frequency is %u kHz\n", *high_freq);
202
203         /* get current borders */
204         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
205         save_lo = msr_lo & 0x0000007F;
206         save_hi = msr_hi & 0x0000007F;
207
208         /* if current perf_pctg is larger than 90%, we need to decrease the
209          * upper limit to make the calculation more accurate.
210          */
211         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
212         /* try decreasing in 10% steps, some processors react only
213          * on some barrier values */
214         for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
215                 /* set to 0 to try_hi perf_pctg */
216                 msr_lo &= 0xFFFFFF80;
217                 msr_hi &= 0xFFFFFF80;
218                 msr_hi |= try_hi;
219                 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
220
221                 /* read out current core MHz and current perf_pctg */
222                 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
223
224                 /* restore values */
225                 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
226         }
227         pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);
228
229         /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
230          * eqals
231          * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
232          *
233          * high_freq * perf_pctg is stored tempoarily into "ebx".
234          */
235         ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
236
237         if ((ecx > 95) || (ecx == 0) || (eax < ebx))
238                 return -EIO;
239
240         edx = ((eax - ebx) * 100) / (100 - ecx);
241         *low_freq = edx * 1000; /* back to kHz */
242
243         pr_debug("low frequency is %u kHz\n", *low_freq);
244
245         if (*low_freq > *high_freq)
246                 *low_freq = *high_freq;
247
248         return 0;
249 }
250
251
252 static int longrun_cpu_init(struct cpufreq_policy *policy)
253 {
254         int result = 0;
255
256         /* capability check */
257         if (policy->cpu != 0)
258                 return -ENODEV;
259
260         /* detect low and high frequency */
261         result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
262         if (result)
263                 return result;
264
265         /* cpuinfo and default policy values */
266         policy->cpuinfo.min_freq = longrun_low_freq;
267         policy->cpuinfo.max_freq = longrun_high_freq;
268         longrun_get_policy(policy);
269
270         return 0;
271 }
272
273
274 static struct cpufreq_driver longrun_driver = {
275         .flags          = CPUFREQ_CONST_LOOPS,
276         .verify         = longrun_verify_policy,
277         .setpolicy      = longrun_set_policy,
278         .get            = longrun_get,
279         .init           = longrun_cpu_init,
280         .name           = "longrun",
281 };
282
283 static const struct x86_cpu_id longrun_ids[] = {
284         X86_MATCH_VENDOR_FEATURE(TRANSMETA, X86_FEATURE_LONGRUN, NULL),
285         {}
286 };
287 MODULE_DEVICE_TABLE(x86cpu, longrun_ids);
288
289 /**
290  * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
291  *
292  * Initializes the LongRun support.
293  */
294 static int __init longrun_init(void)
295 {
296         if (!x86_match_cpu(longrun_ids))
297                 return -ENODEV;
298         return cpufreq_register_driver(&longrun_driver);
299 }
300
301
302 /**
303  * longrun_exit - unregisters LongRun support
304  */
305 static void __exit longrun_exit(void)
306 {
307         cpufreq_unregister_driver(&longrun_driver);
308 }
309
310
311 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
312 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
313                 "Efficeon processors.");
314 MODULE_LICENSE("GPL");
315
316 module_init(longrun_init);
317 module_exit(longrun_exit);