Merge branch 'core-iommu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6.git] / drivers / cpufreq / longrun.c
1 /*
2  * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
3  *
4  *  Licensed under the terms of the GNU GPL License version 2.
5  *
6  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
7  */
8
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/cpufreq.h>
13 #include <linux/timex.h>
14
15 #include <asm/msr.h>
16 #include <asm/processor.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 __cpuinit 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 *policy)
126 {
127         if (!policy)
128                 return -EINVAL;
129
130         policy->cpu = 0;
131         cpufreq_verify_within_limits(policy,
132                 policy->cpuinfo.min_freq,
133                 policy->cpuinfo.max_freq);
134
135         if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
136             (policy->policy != CPUFREQ_POLICY_PERFORMANCE))
137                 return -EINVAL;
138
139         return 0;
140 }
141
142 static unsigned int longrun_get(unsigned int cpu)
143 {
144         u32 eax, ebx, ecx, edx;
145
146         if (cpu)
147                 return 0;
148
149         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
150         pr_debug("cpuid eax is %u\n", eax);
151
152         return eax * 1000;
153 }
154
155 /**
156  * longrun_determine_freqs - determines the lowest and highest possible core frequency
157  * @low_freq: an int to put the lowest frequency into
158  * @high_freq: an int to put the highest frequency into
159  *
160  * Determines the lowest and highest possible core frequencies on this CPU.
161  * This is necessary to calculate the performance percentage according to
162  * TMTA rules:
163  * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
164  */
165 static int __cpuinit longrun_determine_freqs(unsigned int *low_freq,
166                                                       unsigned int *high_freq)
167 {
168         u32 msr_lo, msr_hi;
169         u32 save_lo, save_hi;
170         u32 eax, ebx, ecx, edx;
171         u32 try_hi;
172         struct cpuinfo_x86 *c = &cpu_data(0);
173
174         if (!low_freq || !high_freq)
175                 return -EINVAL;
176
177         if (cpu_has(c, X86_FEATURE_LRTI)) {
178                 /* if the LongRun Table Interface is present, the
179                  * detection is a bit easier:
180                  * For minimum frequency, read out the maximum
181                  * level (msr_hi), write that into "currently
182                  * selected level", and read out the frequency.
183                  * For maximum frequency, read out level zero.
184                  */
185                 /* minimum */
186                 rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
187                 wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
188                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
189                 *low_freq = msr_lo * 1000; /* to kHz */
190
191                 /* maximum */
192                 wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
193                 rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
194                 *high_freq = msr_lo * 1000; /* to kHz */
195
196                 pr_debug("longrun table interface told %u - %u kHz\n",
197                                 *low_freq, *high_freq);
198
199                 if (*low_freq > *high_freq)
200                         *low_freq = *high_freq;
201                 return 0;
202         }
203
204         /* set the upper border to the value determined during TSC init */
205         *high_freq = (cpu_khz / 1000);
206         *high_freq = *high_freq * 1000;
207         pr_debug("high frequency is %u kHz\n", *high_freq);
208
209         /* get current borders */
210         rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
211         save_lo = msr_lo & 0x0000007F;
212         save_hi = msr_hi & 0x0000007F;
213
214         /* if current perf_pctg is larger than 90%, we need to decrease the
215          * upper limit to make the calculation more accurate.
216          */
217         cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
218         /* try decreasing in 10% steps, some processors react only
219          * on some barrier values */
220         for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
221                 /* set to 0 to try_hi perf_pctg */
222                 msr_lo &= 0xFFFFFF80;
223                 msr_hi &= 0xFFFFFF80;
224                 msr_hi |= try_hi;
225                 wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
226
227                 /* read out current core MHz and current perf_pctg */
228                 cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
229
230                 /* restore values */
231                 wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
232         }
233         pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);
234
235         /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
236          * eqals
237          * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
238          *
239          * high_freq * perf_pctg is stored tempoarily into "ebx".
240          */
241         ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
242
243         if ((ecx > 95) || (ecx == 0) || (eax < ebx))
244                 return -EIO;
245
246         edx = ((eax - ebx) * 100) / (100 - ecx);
247         *low_freq = edx * 1000; /* back to kHz */
248
249         pr_debug("low frequency is %u kHz\n", *low_freq);
250
251         if (*low_freq > *high_freq)
252                 *low_freq = *high_freq;
253
254         return 0;
255 }
256
257
258 static int __cpuinit longrun_cpu_init(struct cpufreq_policy *policy)
259 {
260         int result = 0;
261
262         /* capability check */
263         if (policy->cpu != 0)
264                 return -ENODEV;
265
266         /* detect low and high frequency */
267         result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
268         if (result)
269                 return result;
270
271         /* cpuinfo and default policy values */
272         policy->cpuinfo.min_freq = longrun_low_freq;
273         policy->cpuinfo.max_freq = longrun_high_freq;
274         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
275         longrun_get_policy(policy);
276
277         return 0;
278 }
279
280
281 static struct cpufreq_driver longrun_driver = {
282         .flags          = CPUFREQ_CONST_LOOPS,
283         .verify         = longrun_verify_policy,
284         .setpolicy      = longrun_set_policy,
285         .get            = longrun_get,
286         .init           = longrun_cpu_init,
287         .name           = "longrun",
288         .owner          = THIS_MODULE,
289 };
290
291
292 /**
293  * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
294  *
295  * Initializes the LongRun support.
296  */
297 static int __init longrun_init(void)
298 {
299         struct cpuinfo_x86 *c = &cpu_data(0);
300
301         if (c->x86_vendor != X86_VENDOR_TRANSMETA ||
302             !cpu_has(c, X86_FEATURE_LONGRUN))
303                 return -ENODEV;
304
305         return cpufreq_register_driver(&longrun_driver);
306 }
307
308
309 /**
310  * longrun_exit - unregisters LongRun support
311  */
312 static void __exit longrun_exit(void)
313 {
314         cpufreq_unregister_driver(&longrun_driver);
315 }
316
317
318 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
319 MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
320                 "Efficeon processors.");
321 MODULE_LICENSE("GPL");
322
323 module_init(longrun_init);
324 module_exit(longrun_exit);