2 * Based on documentation provided by Dave Jones. Thanks!
4 * Licensed under the terms of the GNU GPL License version 2.
6 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
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>
17 #include <linux/delay.h>
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
30 struct cpufreq_frequency_table freq_table[];
33 static struct eps_cpu_data *eps_cpu[NR_CPUS];
35 /* Module parameters */
36 static int freq_failsafe_off;
37 static int voltage_failsafe_off;
40 static unsigned int eps_get(unsigned int cpu)
42 struct eps_cpu_data *centaur;
47 centaur = eps_cpu[cpu];
51 /* Return current frequency */
52 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
53 return centaur->fsb * ((lo >> 8) & 0xff);
56 static int eps_set_state(struct eps_cpu_data *centaur,
60 struct cpufreq_freqs freqs;
65 freqs.old = eps_get(cpu);
66 freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
68 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
70 /* Wait while CPU is busy */
71 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
73 while (lo & ((1 << 16) | (1 << 17))) {
75 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
77 if (unlikely(i > 64)) {
82 /* Set new multiplier and voltage */
83 wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
84 /* Wait until transition end */
88 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
90 if (unlikely(i > 64)) {
94 } while (lo & ((1 << 16) | (1 << 17)));
96 /* Return current frequency */
98 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
99 freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
103 u8 current_multiplier, current_voltage;
105 /* Print voltage and multiplier */
106 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
107 current_voltage = lo & 0xff;
108 printk(KERN_INFO "eps: Current voltage = %dmV\n",
109 current_voltage * 16 + 700);
110 current_multiplier = (lo >> 8) & 0xff;
111 printk(KERN_INFO "eps: Current multiplier = %d\n",
115 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
119 static int eps_target(struct cpufreq_policy *policy,
120 unsigned int target_freq,
121 unsigned int relation)
123 struct eps_cpu_data *centaur;
124 unsigned int newstate = 0;
125 unsigned int cpu = policy->cpu;
126 unsigned int dest_state;
129 if (unlikely(eps_cpu[cpu] == NULL))
131 centaur = eps_cpu[cpu];
133 if (unlikely(cpufreq_frequency_table_target(policy,
134 &eps_cpu[cpu]->freq_table[0],
141 /* Make frequency transition */
142 dest_state = centaur->freq_table[newstate].index & 0xffff;
143 ret = eps_set_state(centaur, cpu, dest_state);
145 printk(KERN_ERR "eps: Timeout!\n");
149 static int eps_verify(struct cpufreq_policy *policy)
151 return cpufreq_frequency_table_verify(policy,
152 &eps_cpu[policy->cpu]->freq_table[0]);
155 static int eps_cpu_init(struct cpufreq_policy *policy)
160 u8 current_multiplier, current_voltage;
161 u8 max_multiplier, max_voltage;
162 u8 min_multiplier, min_voltage;
165 struct eps_cpu_data *centaur;
166 struct cpuinfo_x86 *c = &cpu_data(0);
167 struct cpufreq_frequency_table *f_table;
168 int k, step, voltage;
172 if (policy->cpu != 0)
176 printk(KERN_INFO "eps: Detected VIA ");
178 switch (c->x86_model) {
180 rdmsr(0x1153, lo, hi);
181 brand = (((lo >> 2) ^ lo) >> 18) & 3;
182 printk(KERN_CONT "Model A ");
185 rdmsr(0x1154, lo, hi);
186 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
187 printk(KERN_CONT "Model D ");
193 printk(KERN_CONT "C7-M\n");
196 printk(KERN_CONT "C7\n");
199 printk(KERN_CONT "Eden\n");
202 printk(KERN_CONT "C7-D\n");
205 printk(KERN_CONT "C3\n");
209 /* Enable Enhanced PowerSaver */
210 rdmsrl(MSR_IA32_MISC_ENABLE, val);
211 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
212 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
213 wrmsrl(MSR_IA32_MISC_ENABLE, val);
214 /* Can be locked at 0 */
215 rdmsrl(MSR_IA32_MISC_ENABLE, val);
216 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
217 printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
222 /* Print voltage and multiplier */
223 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
224 current_voltage = lo & 0xff;
225 printk(KERN_INFO "eps: Current voltage = %dmV\n",
226 current_voltage * 16 + 700);
227 current_multiplier = (lo >> 8) & 0xff;
228 printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
231 max_voltage = hi & 0xff;
232 printk(KERN_INFO "eps: Highest voltage = %dmV\n",
233 max_voltage * 16 + 700);
234 max_multiplier = (hi >> 8) & 0xff;
235 printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
236 min_voltage = (hi >> 16) & 0xff;
237 printk(KERN_INFO "eps: Lowest voltage = %dmV\n",
238 min_voltage * 16 + 700);
239 min_multiplier = (hi >> 24) & 0xff;
240 printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
243 if (current_multiplier == 0 || max_multiplier == 0
244 || min_multiplier == 0)
246 if (current_multiplier > max_multiplier
247 || max_multiplier <= min_multiplier)
249 if (current_voltage > 0x1f || max_voltage > 0x1f)
251 if (max_voltage < min_voltage
252 || current_voltage < min_voltage
253 || current_voltage > max_voltage)
256 /* Check for systems using underclocked CPU */
257 if (!freq_failsafe_off && max_multiplier != current_multiplier) {
258 printk(KERN_INFO "eps: Your processor is running at different "
259 "frequency then its maximum. Aborting.\n");
260 printk(KERN_INFO "eps: You can use freq_failsafe_off option "
261 "to disable this check.\n");
264 if (!voltage_failsafe_off && max_voltage != current_voltage) {
265 printk(KERN_INFO "eps: Your processor is running at different "
266 "voltage then its maximum. Aborting.\n");
267 printk(KERN_INFO "eps: You can use voltage_failsafe_off "
268 "option to disable this check.\n");
273 fsb = cpu_khz / current_multiplier;
274 /* Calc number of p-states supported */
275 if (brand == EPS_BRAND_C7M)
276 states = max_multiplier - min_multiplier + 1;
280 /* Allocate private data and frequency table for current cpu */
281 centaur = kzalloc(sizeof(struct eps_cpu_data)
282 + (states + 1) * sizeof(struct cpufreq_frequency_table),
286 eps_cpu[0] = centaur;
288 /* Copy basic values */
291 /* Fill frequency and MSR value table */
292 f_table = ¢aur->freq_table[0];
293 if (brand != EPS_BRAND_C7M) {
294 f_table[0].frequency = fsb * min_multiplier;
295 f_table[0].index = (min_multiplier << 8) | min_voltage;
296 f_table[1].frequency = fsb * max_multiplier;
297 f_table[1].index = (max_multiplier << 8) | max_voltage;
298 f_table[2].frequency = CPUFREQ_TABLE_END;
301 step = ((max_voltage - min_voltage) * 256)
302 / (max_multiplier - min_multiplier);
303 for (i = min_multiplier; i <= max_multiplier; i++) {
304 voltage = (k * step) / 256 + min_voltage;
305 f_table[k].frequency = fsb * i;
306 f_table[k].index = (i << 8) | voltage;
309 f_table[k].frequency = CPUFREQ_TABLE_END;
312 policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
313 policy->cur = fsb * current_multiplier;
315 ret = cpufreq_frequency_table_cpuinfo(policy, ¢aur->freq_table[0]);
321 cpufreq_frequency_table_get_attr(¢aur->freq_table[0], policy->cpu);
325 static int eps_cpu_exit(struct cpufreq_policy *policy)
327 unsigned int cpu = policy->cpu;
330 cpufreq_frequency_table_put_attr(policy->cpu);
336 static struct freq_attr *eps_attr[] = {
337 &cpufreq_freq_attr_scaling_available_freqs,
341 static struct cpufreq_driver eps_driver = {
342 .verify = eps_verify,
343 .target = eps_target,
344 .init = eps_cpu_init,
345 .exit = eps_cpu_exit,
347 .name = "e_powersaver",
348 .owner = THIS_MODULE,
352 static int __init eps_init(void)
354 struct cpuinfo_x86 *c = &cpu_data(0);
356 /* This driver will work only on Centaur C7 processors with
357 * Enhanced SpeedStep/PowerSaver registers */
358 if (c->x86_vendor != X86_VENDOR_CENTAUR
359 || c->x86 != 6 || c->x86_model < 10)
361 if (!cpu_has(c, X86_FEATURE_EST))
364 if (cpufreq_register_driver(&eps_driver))
369 static void __exit eps_exit(void)
371 cpufreq_unregister_driver(&eps_driver);
374 /* Allow user to overclock his machine or to change frequency to higher after
375 * unloading module */
376 module_param(freq_failsafe_off, int, 0644);
377 MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
378 module_param(voltage_failsafe_off, int, 0644);
379 MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
381 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
382 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
383 MODULE_LICENSE("GPL");
385 module_init(eps_init);
386 module_exit(eps_exit);