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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * (C) 2002 - 2003 Dominik Brodowski <[email protected]>
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#include <asm/cpuid/api.h>
18
19static struct cpufreq_driver longrun_driver;
20
21/**
22 * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
23 * values into per cent values. In TMTA microcode, the following is valid:
24 * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
25 */
26static unsigned int longrun_low_freq, longrun_high_freq;
27
28
29/**
30 * longrun_get_policy - get the current LongRun policy
31 * @policy: struct cpufreq_policy where current policy is written into
32 *
33 * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
34 * and MSR_TMTA_LONGRUN_CTRL
35 */
36static void longrun_get_policy(struct cpufreq_policy *policy)
37{
38 struct msr msr;
39
40 rdmsrq(MSR_TMTA_LONGRUN_FLAGS, msr.q);
41 pr_debug("longrun flags are %x - %x\n", msr.l, msr.h);
42 if (msr.l & 0x01)
43 policy->policy = CPUFREQ_POLICY_PERFORMANCE;
44 else
45 policy->policy = CPUFREQ_POLICY_POWERSAVE;
46
47 rdmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q);
48 pr_debug("longrun ctrl is %x - %x\n", msr.l, msr.h);
49 msr.l &= 0x0000007F;
50 msr.h &= 0x0000007F;
51
52 if (longrun_high_freq <= longrun_low_freq) {
53 /* Assume degenerate Longrun table */
54 policy->min = policy->max = longrun_high_freq;
55 } else {
56 policy->min = longrun_low_freq + msr.l *
57 ((longrun_high_freq - longrun_low_freq) / 100);
58 policy->max = longrun_low_freq + msr.h *
59 ((longrun_high_freq - longrun_low_freq) / 100);
60 }
61 policy->cpu = 0;
62}
63
64
65/**
66 * longrun_set_policy - sets a new CPUFreq policy
67 * @policy: new policy
68 *
69 * Sets a new CPUFreq policy on LongRun-capable processors. This function
70 * has to be called with cpufreq_driver locked.
71 */
72static int longrun_set_policy(struct cpufreq_policy *policy)
73{
74 struct msr msr;
75 u32 pctg_lo, pctg_hi;
76
77 if (!policy)
78 return -EINVAL;
79
80 if (longrun_high_freq <= longrun_low_freq) {
81 /* Assume degenerate Longrun table */
82 pctg_lo = pctg_hi = 100;
83 } else {
84 pctg_lo = (policy->min - longrun_low_freq) /
85 ((longrun_high_freq - longrun_low_freq) / 100);
86 pctg_hi = (policy->max - longrun_low_freq) /
87 ((longrun_high_freq - longrun_low_freq) / 100);
88 }
89
90 if (pctg_hi > 100)
91 pctg_hi = 100;
92 if (pctg_lo > pctg_hi)
93 pctg_lo = pctg_hi;
94
95 /* performance or economy mode */
96 rdmsrq(MSR_TMTA_LONGRUN_FLAGS, msr.q);
97 msr.l &= 0xFFFFFFFE;
98 switch (policy->policy) {
99 case CPUFREQ_POLICY_PERFORMANCE:
100 msr.l |= 0x00000001;
101 break;
102 case CPUFREQ_POLICY_POWERSAVE:
103 break;
104 }
105 wrmsrq(MSR_TMTA_LONGRUN_FLAGS, msr.q);
106
107 /* lower and upper boundary */
108 rdmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q);
109 msr.l &= 0xFFFFFF80;
110 msr.h &= 0xFFFFFF80;
111 msr.l |= pctg_lo;
112 msr.h |= pctg_hi;
113 wrmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q);
114
115 return 0;
116}
117
118
119/**
120 * longrun_verify_poliy - verifies a new CPUFreq policy
121 * @policy: the policy to verify
122 *
123 * Validates a new CPUFreq policy. This function has to be called with
124 * cpufreq_driver locked.
125 */
126static int longrun_verify_policy(struct cpufreq_policy_data *policy)
127{
128 if (!policy)
129 return -EINVAL;
130
131 policy->cpu = 0;
132 cpufreq_verify_within_cpu_limits(policy);
133
134 return 0;
135}
136
137static unsigned int longrun_get(unsigned int cpu)
138{
139 u32 eax, ebx, ecx, edx;
140
141 if (cpu)
142 return 0;
143
144 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
145 pr_debug("cpuid eax is %u\n", eax);
146
147 return eax * 1000;
148}
149
150/**
151 * longrun_determine_freqs - determines the lowest and highest possible core frequency
152 * @low_freq: an int to put the lowest frequency into
153 * @high_freq: an int to put the highest frequency into
154 *
155 * Determines the lowest and highest possible core frequencies on this CPU.
156 * This is necessary to calculate the performance percentage according to
157 * TMTA rules:
158 * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
159 */
160static int longrun_determine_freqs(unsigned int *low_freq,
161 unsigned int *high_freq)
162{
163 struct msr msr, save;
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 rdmsrq(MSR_TMTA_LRTI_READOUT, msr.q);
181 msr.l = msr.h;
182 wrmsrq(MSR_TMTA_LRTI_READOUT, msr.q);
183 rdmsrq(MSR_TMTA_LRTI_VOLT_MHZ, msr.q);
184 *low_freq = msr.l * 1000; /* to kHz */
185
186 /* maximum */
187 msr.l = 0;
188 wrmsrq(MSR_TMTA_LRTI_READOUT, msr.q);
189 rdmsrq(MSR_TMTA_LRTI_VOLT_MHZ, msr.q);
190 *high_freq = msr.l * 1000; /* to kHz */
191
192 pr_debug("longrun table interface told %u - %u kHz\n",
193 *low_freq, *high_freq);
194
195 if (*low_freq > *high_freq)
196 *low_freq = *high_freq;
197 return 0;
198 }
199
200 /* set the upper border to the value determined during TSC init */
201 *high_freq = (cpu_khz / 1000);
202 *high_freq = *high_freq * 1000;
203 pr_debug("high frequency is %u kHz\n", *high_freq);
204
205 /* get current borders */
206 rdmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q);
207 save.l = msr.l & 0x0000007F;
208 save.h = msr.h & 0x0000007F;
209
210 /* if current perf_pctg is larger than 90%, we need to decrease the
211 * upper limit to make the calculation more accurate.
212 */
213 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
214 /* try decreasing in 10% steps, some processors react only
215 * on some barrier values */
216 for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
217 /* set to 0 to try_hi perf_pctg */
218 msr.l &= 0xFFFFFF80;
219 msr.h &= 0xFFFFFF80;
220 msr.h |= try_hi;
221 wrmsrq(MSR_TMTA_LONGRUN_CTRL, msr.q);
222
223 /* read out current core MHz and current perf_pctg */
224 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
225
226 /* restore values */
227 wrmsrq(MSR_TMTA_LONGRUN_CTRL, save.q);
228 }
229 pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);
230
231 /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
232 * eqals
233 * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
234 *
235 * high_freq * perf_pctg is stored tempoarily into "ebx".
236 */
237 ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
238
239 if ((ecx > 95) || (ecx == 0) || (eax < ebx))
240 return -EIO;
241
242 edx = ((eax - ebx) * 100) / (100 - ecx);
243 *low_freq = edx * 1000; /* back to kHz */
244
245 pr_debug("low frequency is %u kHz\n", *low_freq);
246
247 if (*low_freq > *high_freq)
248 *low_freq = *high_freq;
249
250 return 0;
251}
252
253
254static int longrun_cpu_init(struct cpufreq_policy *policy)
255{
256 int result = 0;
257
258 /* capability check */
259 if (policy->cpu != 0)
260 return -ENODEV;
261
262 /* detect low and high frequency */
263 result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
264 if (result)
265 return result;
266
267 /* cpuinfo and default policy values */
268 policy->cpuinfo.min_freq = longrun_low_freq;
269 policy->cpuinfo.max_freq = longrun_high_freq;
270 longrun_get_policy(policy);
271
272 return 0;
273}
274
275
276static struct cpufreq_driver longrun_driver = {
277 .flags = CPUFREQ_CONST_LOOPS,
278 .verify = longrun_verify_policy,
279 .setpolicy = longrun_set_policy,
280 .get = longrun_get,
281 .init = longrun_cpu_init,
282 .name = "longrun",
283};
284
285static const struct x86_cpu_id longrun_ids[] = {
286 X86_MATCH_VENDOR_FEATURE(TRANSMETA, X86_FEATURE_LONGRUN, NULL),
287 {}
288};
289MODULE_DEVICE_TABLE(x86cpu, longrun_ids);
290
291/**
292 * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
293 *
294 * Initializes the LongRun support.
295 */
296static int __init longrun_init(void)
297{
298 if (!x86_match_cpu(longrun_ids))
299 return -ENODEV;
300 return cpufreq_register_driver(&longrun_driver);
301}
302
303
304/**
305 * longrun_exit - unregisters LongRun support
306 */
307static void __exit longrun_exit(void)
308{
309 cpufreq_unregister_driver(&longrun_driver);
310}
311
312
313MODULE_AUTHOR("Dominik Brodowski <[email protected]>");
314MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
315 "Efficeon processors.");
316MODULE_LICENSE("GPL");
317
318module_init(longrun_init);
319module_exit(longrun_exit);