1 /*
2 * Based on documentation provided by Dave Jones. Thanks!
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/ioport.h>
14 #include <linux/slab.h>
15 #include <linux/timex.h>
16 #include <linux/io.h>
17 #include <linux/delay.h>
18
19 #include <asm/msr.h>
20 #include <asm/tsc.h>
21
22 #define EPS_BRAND_C7M 0
23 #define EPS_BRAND_C7 1
24 #define EPS_BRAND_EDEN 2
25 #define EPS_BRAND_C3 3
26 #define EPS_BRAND_C7D 4
27
28 struct eps_cpu_data {
29 u32 fsb;
30 struct cpufreq_frequency_table freq_table[];
31 };
32
33 static struct eps_cpu_data *eps_cpu[NR_CPUS];
34
35
36 static unsigned int eps_get(unsigned int cpu)
37 {
38 struct eps_cpu_data *centaur;
39 u32 lo, hi;
40
41 if (cpu)
42 return 0;
43 centaur = eps_cpu[cpu];
44 if (centaur == NULL)
45 return 0;
46
47 /* Return current frequency */
48 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
49 return centaur->fsb * ((lo >> 8) & 0xff);
50 }
51
52 static int eps_set_state(struct eps_cpu_data *centaur,
53 unsigned int cpu,
54 u32 dest_state)
55 {
56 struct cpufreq_freqs freqs;
57 u32 lo, hi;
58 int err = 0;
59 int i;
60
61 freqs.old = eps_get(cpu);
62 freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
63 freqs.cpu = cpu;
64 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
65
66 /* Wait while CPU is busy */
67 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
68 i = 0;
69 while (lo & ((1 << 16) | (1 << 17))) {
70 udelay(16);
71 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
72 i++;
73 if (unlikely(i > 64)) {
74 err = -ENODEV;
75 goto postchange;
76 }
77 }
78 /* Set new multiplier and voltage */
79 wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
80 /* Wait until transition end */
81 i = 0;
82 do {
83 udelay(16);
84 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
85 i++;
86 if (unlikely(i > 64)) {
87 err = -ENODEV;
88 goto postchange;
89 }
90 } while (lo & ((1 << 16) | (1 << 17)));
91
92 /* Return current frequency */
93 postchange:
94 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
95 freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
96
97 #ifdef DEBUG
98 {
99 u8 current_multiplier, current_voltage;
100
101 /* Print voltage and multiplier */
102 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
103 current_voltage = lo & 0xff;
104 printk(KERN_INFO "eps: Current voltage = %dmV\n",
105 current_voltage * 16 + 700);
106 current_multiplier = (lo >> 8) & 0xff;
107 printk(KERN_INFO "eps: Current multiplier = %d\n",
108 current_multiplier);
109 }
110 #endif
111 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
112 return err;
113 }
114
115 static int eps_target(struct cpufreq_policy *policy,
116 unsigned int target_freq,
117 unsigned int relation)
118 {
119 struct eps_cpu_data *centaur;
120 unsigned int newstate = 0;
121 unsigned int cpu = policy->cpu;
122 unsigned int dest_state;
123 int ret;
124
125 if (unlikely(eps_cpu[cpu] == NULL))
126 return -ENODEV;
127 centaur = eps_cpu[cpu];
128
129 if (unlikely(cpufreq_frequency_table_target(policy,
130 &eps_cpu[cpu]->freq_table[0],
131 target_freq,
132 relation,
133 &newstate))) {
134 return -EINVAL;
135 }
136
137 /* Make frequency transition */
138 dest_state = centaur->freq_table[newstate].index & 0xffff;
139 ret = eps_set_state(centaur, cpu, dest_state);
140 if (ret)
141 printk(KERN_ERR "eps: Timeout!\n");
142 return ret;
143 }
144
145 static int eps_verify(struct cpufreq_policy *policy)
146 {
147 return cpufreq_frequency_table_verify(policy,
148 &eps_cpu[policy->cpu]->freq_table[0]);
149 }
150
151 static int eps_cpu_init(struct cpufreq_policy *policy)
152 {
153 unsigned int i;
154 u32 lo, hi;
155 u64 val;
156 u8 current_multiplier, current_voltage;
157 u8 max_multiplier, max_voltage;
158 u8 min_multiplier, min_voltage;
159 u8 brand = 0;
160 u32 fsb;
161 struct eps_cpu_data *centaur;
162 struct cpuinfo_x86 *c = &cpu_data(0);
163 struct cpufreq_frequency_table *f_table;
164 int k, step, voltage;
165 int ret;
166 int states;
167
168 if (policy->cpu != 0)
169 return -ENODEV;
170
171 /* Check brand */
172 printk(KERN_INFO "eps: Detected VIA ");
173
174 switch (c->x86_model) {
175 case 10:
176 rdmsr(0x1153, lo, hi);
177 brand = (((lo >> 2) ^ lo) >> 18) & 3;
178 printk(KERN_CONT "Model A ");
179 break;
180 case 13:
181 rdmsr(0x1154, lo, hi);
182 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
183 printk(KERN_CONT "Model D ");
184 break;
185 }
186
187 switch (brand) {
188 case EPS_BRAND_C7M:
189 printk(KERN_CONT "C7-M\n");
190 break;
191 case EPS_BRAND_C7:
192 printk(KERN_CONT "C7\n");
193 break;
194 case EPS_BRAND_EDEN:
195 printk(KERN_CONT "Eden\n");
196 break;
197 case EPS_BRAND_C7D:
198 printk(KERN_CONT "C7-D\n");
199 break;
200 case EPS_BRAND_C3:
201 printk(KERN_CONT "C3\n");
202 return -ENODEV;
203 break;
204 }
205 /* Enable Enhanced PowerSaver */
206 rdmsrl(MSR_IA32_MISC_ENABLE, val);
207 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
208 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
209 wrmsrl(MSR_IA32_MISC_ENABLE, val);
210 /* Can be locked at 0 */
211 rdmsrl(MSR_IA32_MISC_ENABLE, val);
212 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
213 printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
214 return -ENODEV;
215 }
216 }
217
218 /* Print voltage and multiplier */
219 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
220 current_voltage = lo & 0xff;
221 printk(KERN_INFO "eps: Current voltage = %dmV\n",
222 current_voltage * 16 + 700);
223 current_multiplier = (lo >> 8) & 0xff;
224 printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
225
226 /* Print limits */
227 max_voltage = hi & 0xff;
228 printk(KERN_INFO "eps: Highest voltage = %dmV\n",
229 max_voltage * 16 + 700);
230 max_multiplier = (hi >> 8) & 0xff;
231 printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
232 min_voltage = (hi >> 16) & 0xff;
233 printk(KERN_INFO "eps: Lowest voltage = %dmV\n",
234 min_voltage * 16 + 700);
235 min_multiplier = (hi >> 24) & 0xff;
236 printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
237
238 /* Sanity checks */
239 if (current_multiplier == 0 || max_multiplier == 0
240 || min_multiplier == 0)
241 return -EINVAL;
242 if (current_multiplier > max_multiplier
243 || max_multiplier <= min_multiplier)
244 return -EINVAL;
245 if (current_voltage > 0x1f || max_voltage > 0x1f)
246 return -EINVAL;
247 if (max_voltage < min_voltage)
248 return -EINVAL;
249
250 /* Calc FSB speed */
251 fsb = cpu_khz / current_multiplier;
252 /* Calc number of p-states supported */
253 if (brand == EPS_BRAND_C7M)
254 states = max_multiplier - min_multiplier + 1;
255 else
256 states = 2;
257
258 /* Allocate private data and frequency table for current cpu */
259 centaur = kzalloc(sizeof(struct eps_cpu_data)
260 + (states + 1) * sizeof(struct cpufreq_frequency_table),
261 GFP_KERNEL);
262 if (!centaur)
263 return -ENOMEM;
264 eps_cpu[0] = centaur;
265
266 /* Copy basic values */
267 centaur->fsb = fsb;
268
269 /* Fill frequency and MSR value table */
270 f_table = ¢aur->freq_table[0];
271 if (brand != EPS_BRAND_C7M) {
272 f_table[0].frequency = fsb * min_multiplier;
273 f_table[0].index = (min_multiplier << 8) | min_voltage;
274 f_table[1].frequency = fsb * max_multiplier;
275 f_table[1].index = (max_multiplier << 8) | max_voltage;
276 f_table[2].frequency = CPUFREQ_TABLE_END;
277 } else {
278 k = 0;
279 step = ((max_voltage - min_voltage) * 256)
280 / (max_multiplier - min_multiplier);
281 for (i = min_multiplier; i <= max_multiplier; i++) {
282 voltage = (k * step) / 256 + min_voltage;
283 f_table[k].frequency = fsb * i;
284 f_table[k].index = (i << 8) | voltage;
285 k++;
286 }
287 f_table[k].frequency = CPUFREQ_TABLE_END;
288 }
289
290 policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
291 policy->cur = fsb * current_multiplier;
292
293 ret = cpufreq_frequency_table_cpuinfo(policy, ¢aur->freq_table[0]);
294 if (ret) {
295 kfree(centaur);
296 return ret;
297 }
298
299 cpufreq_frequency_table_get_attr(¢aur->freq_table[0], policy->cpu);
300 return 0;
301 }
302
303 static int eps_cpu_exit(struct cpufreq_policy *policy)
304 {
305 unsigned int cpu = policy->cpu;
306 struct eps_cpu_data *centaur;
307 u32 lo, hi;
308
309 if (eps_cpu[cpu] == NULL)
310 return -ENODEV;
311 centaur = eps_cpu[cpu];
312
313 /* Get max frequency */
314 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
315 /* Set max frequency */
316 eps_set_state(centaur, cpu, hi & 0xffff);
317 /* Bye */
318 cpufreq_frequency_table_put_attr(policy->cpu);
319 kfree(eps_cpu[cpu]);
320 eps_cpu[cpu] = NULL;
321 return 0;
322 }
323
324 static struct freq_attr *eps_attr[] = {
325 &cpufreq_freq_attr_scaling_available_freqs,
326 NULL,
327 };
328
329 static struct cpufreq_driver eps_driver = {
330 .verify = eps_verify,
331 .target = eps_target,
332 .init = eps_cpu_init,
333 .exit = eps_cpu_exit,
334 .get = eps_get,
335 .name = "e_powersaver",
336 .owner = THIS_MODULE,
337 .attr = eps_attr,
338 };
339
340 static int __init eps_init(void)
341 {
342 struct cpuinfo_x86 *c = &cpu_data(0);
343
344 /* This driver will work only on Centaur C7 processors with
345 * Enhanced SpeedStep/PowerSaver registers */
346 if (c->x86_vendor != X86_VENDOR_CENTAUR
347 || c->x86 != 6 || c->x86_model < 10)
348 return -ENODEV;
349 if (!cpu_has(c, X86_FEATURE_EST))
350 return -ENODEV;
351
352 if (cpufreq_register_driver(&eps_driver))
353 return -EINVAL;
354 return 0;
355 }
356
357 static void __exit eps_exit(void)
358 {
359 cpufreq_unregister_driver(&eps_driver);
360 }
361
362 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
363 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
364 MODULE_LICENSE("GPL");
365
366 module_init(eps_init);
367 module_exit(eps_exit);
368
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