Root/drivers/cpufreq/e_powersaver.c

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/cpu_device_id.h>
20#include <asm/msr.h>
21#include <asm/tsc.h>
22
23#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
24#include <linux/acpi.h>
25#include <acpi/processor.h>
26#endif
27
28#define EPS_BRAND_C7M 0
29#define EPS_BRAND_C7 1
30#define EPS_BRAND_EDEN 2
31#define EPS_BRAND_C3 3
32#define EPS_BRAND_C7D 4
33
34struct eps_cpu_data {
35    u32 fsb;
36#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
37    u32 bios_limit;
38#endif
39    struct cpufreq_frequency_table freq_table[];
40};
41
42static struct eps_cpu_data *eps_cpu[NR_CPUS];
43
44/* Module parameters */
45static int freq_failsafe_off;
46static int voltage_failsafe_off;
47static int set_max_voltage;
48
49#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
50static int ignore_acpi_limit;
51
52static struct acpi_processor_performance *eps_acpi_cpu_perf;
53
54/* Minimum necessary to get acpi_processor_get_bios_limit() working */
55static int eps_acpi_init(void)
56{
57    eps_acpi_cpu_perf = kzalloc(sizeof(struct acpi_processor_performance),
58                      GFP_KERNEL);
59    if (!eps_acpi_cpu_perf)
60        return -ENOMEM;
61
62    if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
63                                GFP_KERNEL)) {
64        kfree(eps_acpi_cpu_perf);
65        eps_acpi_cpu_perf = NULL;
66        return -ENOMEM;
67    }
68
69    if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
70        free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
71        kfree(eps_acpi_cpu_perf);
72        eps_acpi_cpu_perf = NULL;
73        return -EIO;
74    }
75    return 0;
76}
77
78static int eps_acpi_exit(struct cpufreq_policy *policy)
79{
80    if (eps_acpi_cpu_perf) {
81        acpi_processor_unregister_performance(eps_acpi_cpu_perf, 0);
82        free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
83        kfree(eps_acpi_cpu_perf);
84        eps_acpi_cpu_perf = NULL;
85    }
86    return 0;
87}
88#endif
89
90static unsigned int eps_get(unsigned int cpu)
91{
92    struct eps_cpu_data *centaur;
93    u32 lo, hi;
94
95    if (cpu)
96        return 0;
97    centaur = eps_cpu[cpu];
98    if (centaur == NULL)
99        return 0;
100
101    /* Return current frequency */
102    rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
103    return centaur->fsb * ((lo >> 8) & 0xff);
104}
105
106static int eps_set_state(struct eps_cpu_data *centaur,
107             unsigned int cpu,
108             u32 dest_state)
109{
110    struct cpufreq_freqs freqs;
111    u32 lo, hi;
112    int err = 0;
113    int i;
114
115    freqs.old = eps_get(cpu);
116    freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
117    freqs.cpu = cpu;
118    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
119
120    /* Wait while CPU is busy */
121    rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
122    i = 0;
123    while (lo & ((1 << 16) | (1 << 17))) {
124        udelay(16);
125        rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
126        i++;
127        if (unlikely(i > 64)) {
128            err = -ENODEV;
129            goto postchange;
130        }
131    }
132    /* Set new multiplier and voltage */
133    wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
134    /* Wait until transition end */
135    i = 0;
136    do {
137        udelay(16);
138        rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
139        i++;
140        if (unlikely(i > 64)) {
141            err = -ENODEV;
142            goto postchange;
143        }
144    } while (lo & ((1 << 16) | (1 << 17)));
145
146    /* Return current frequency */
147postchange:
148    rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
149    freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
150
151#ifdef DEBUG
152    {
153    u8 current_multiplier, current_voltage;
154
155    /* Print voltage and multiplier */
156    rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
157    current_voltage = lo & 0xff;
158    printk(KERN_INFO "eps: Current voltage = %dmV\n",
159        current_voltage * 16 + 700);
160    current_multiplier = (lo >> 8) & 0xff;
161    printk(KERN_INFO "eps: Current multiplier = %d\n",
162        current_multiplier);
163    }
164#endif
165    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
166    return err;
167}
168
169static int eps_target(struct cpufreq_policy *policy,
170                   unsigned int target_freq,
171                   unsigned int relation)
172{
173    struct eps_cpu_data *centaur;
174    unsigned int newstate = 0;
175    unsigned int cpu = policy->cpu;
176    unsigned int dest_state;
177    int ret;
178
179    if (unlikely(eps_cpu[cpu] == NULL))
180        return -ENODEV;
181    centaur = eps_cpu[cpu];
182
183    if (unlikely(cpufreq_frequency_table_target(policy,
184            &eps_cpu[cpu]->freq_table[0],
185            target_freq,
186            relation,
187            &newstate))) {
188        return -EINVAL;
189    }
190
191    /* Make frequency transition */
192    dest_state = centaur->freq_table[newstate].index & 0xffff;
193    ret = eps_set_state(centaur, cpu, dest_state);
194    if (ret)
195        printk(KERN_ERR "eps: Timeout!\n");
196    return ret;
197}
198
199static int eps_verify(struct cpufreq_policy *policy)
200{
201    return cpufreq_frequency_table_verify(policy,
202            &eps_cpu[policy->cpu]->freq_table[0]);
203}
204
205static int eps_cpu_init(struct cpufreq_policy *policy)
206{
207    unsigned int i;
208    u32 lo, hi;
209    u64 val;
210    u8 current_multiplier, current_voltage;
211    u8 max_multiplier, max_voltage;
212    u8 min_multiplier, min_voltage;
213    u8 brand = 0;
214    u32 fsb;
215    struct eps_cpu_data *centaur;
216    struct cpuinfo_x86 *c = &cpu_data(0);
217    struct cpufreq_frequency_table *f_table;
218    int k, step, voltage;
219    int ret;
220    int states;
221#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
222    unsigned int limit;
223#endif
224
225    if (policy->cpu != 0)
226        return -ENODEV;
227
228    /* Check brand */
229    printk(KERN_INFO "eps: Detected VIA ");
230
231    switch (c->x86_model) {
232    case 10:
233        rdmsr(0x1153, lo, hi);
234        brand = (((lo >> 2) ^ lo) >> 18) & 3;
235        printk(KERN_CONT "Model A ");
236        break;
237    case 13:
238        rdmsr(0x1154, lo, hi);
239        brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
240        printk(KERN_CONT "Model D ");
241        break;
242    }
243
244    switch (brand) {
245    case EPS_BRAND_C7M:
246        printk(KERN_CONT "C7-M\n");
247        break;
248    case EPS_BRAND_C7:
249        printk(KERN_CONT "C7\n");
250        break;
251    case EPS_BRAND_EDEN:
252        printk(KERN_CONT "Eden\n");
253        break;
254    case EPS_BRAND_C7D:
255        printk(KERN_CONT "C7-D\n");
256        break;
257    case EPS_BRAND_C3:
258        printk(KERN_CONT "C3\n");
259        return -ENODEV;
260        break;
261    }
262    /* Enable Enhanced PowerSaver */
263    rdmsrl(MSR_IA32_MISC_ENABLE, val);
264    if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
265        val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
266        wrmsrl(MSR_IA32_MISC_ENABLE, val);
267        /* Can be locked at 0 */
268        rdmsrl(MSR_IA32_MISC_ENABLE, val);
269        if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
270            printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
271            return -ENODEV;
272        }
273    }
274
275    /* Print voltage and multiplier */
276    rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
277    current_voltage = lo & 0xff;
278    printk(KERN_INFO "eps: Current voltage = %dmV\n",
279            current_voltage * 16 + 700);
280    current_multiplier = (lo >> 8) & 0xff;
281    printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
282
283    /* Print limits */
284    max_voltage = hi & 0xff;
285    printk(KERN_INFO "eps: Highest voltage = %dmV\n",
286            max_voltage * 16 + 700);
287    max_multiplier = (hi >> 8) & 0xff;
288    printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
289    min_voltage = (hi >> 16) & 0xff;
290    printk(KERN_INFO "eps: Lowest voltage = %dmV\n",
291            min_voltage * 16 + 700);
292    min_multiplier = (hi >> 24) & 0xff;
293    printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
294
295    /* Sanity checks */
296    if (current_multiplier == 0 || max_multiplier == 0
297        || min_multiplier == 0)
298        return -EINVAL;
299    if (current_multiplier > max_multiplier
300        || max_multiplier <= min_multiplier)
301        return -EINVAL;
302    if (current_voltage > 0x1f || max_voltage > 0x1f)
303        return -EINVAL;
304    if (max_voltage < min_voltage
305        || current_voltage < min_voltage
306        || current_voltage > max_voltage)
307        return -EINVAL;
308
309    /* Check for systems using underclocked CPU */
310    if (!freq_failsafe_off && max_multiplier != current_multiplier) {
311        printk(KERN_INFO "eps: Your processor is running at different "
312            "frequency then its maximum. Aborting.\n");
313        printk(KERN_INFO "eps: You can use freq_failsafe_off option "
314            "to disable this check.\n");
315        return -EINVAL;
316    }
317    if (!voltage_failsafe_off && max_voltage != current_voltage) {
318        printk(KERN_INFO "eps: Your processor is running at different "
319            "voltage then its maximum. Aborting.\n");
320        printk(KERN_INFO "eps: You can use voltage_failsafe_off "
321            "option to disable this check.\n");
322        return -EINVAL;
323    }
324
325    /* Calc FSB speed */
326    fsb = cpu_khz / current_multiplier;
327
328#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
329    /* Check for ACPI processor speed limit */
330    if (!ignore_acpi_limit && !eps_acpi_init()) {
331        if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
332            printk(KERN_INFO "eps: ACPI limit %u.%uGHz\n",
333                limit/1000000,
334                (limit%1000000)/10000);
335            eps_acpi_exit(policy);
336            /* Check if max_multiplier is in BIOS limits */
337            if (limit && max_multiplier * fsb > limit) {
338                printk(KERN_INFO "eps: Aborting.\n");
339                return -EINVAL;
340            }
341        }
342    }
343#endif
344
345    /* Allow user to set lower maximum voltage then that reported
346     * by processor */
347    if (brand == EPS_BRAND_C7M && set_max_voltage) {
348        u32 v;
349
350        /* Change mV to something hardware can use */
351        v = (set_max_voltage - 700) / 16;
352        /* Check if voltage is within limits */
353        if (v >= min_voltage && v <= max_voltage) {
354            printk(KERN_INFO "eps: Setting %dmV as maximum.\n",
355                v * 16 + 700);
356            max_voltage = v;
357        }
358    }
359
360    /* Calc number of p-states supported */
361    if (brand == EPS_BRAND_C7M)
362        states = max_multiplier - min_multiplier + 1;
363    else
364        states = 2;
365
366    /* Allocate private data and frequency table for current cpu */
367    centaur = kzalloc(sizeof(struct eps_cpu_data)
368            + (states + 1) * sizeof(struct cpufreq_frequency_table),
369            GFP_KERNEL);
370    if (!centaur)
371        return -ENOMEM;
372    eps_cpu[0] = centaur;
373
374    /* Copy basic values */
375    centaur->fsb = fsb;
376#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
377    centaur->bios_limit = limit;
378#endif
379
380    /* Fill frequency and MSR value table */
381    f_table = &centaur->freq_table[0];
382    if (brand != EPS_BRAND_C7M) {
383        f_table[0].frequency = fsb * min_multiplier;
384        f_table[0].index = (min_multiplier << 8) | min_voltage;
385        f_table[1].frequency = fsb * max_multiplier;
386        f_table[1].index = (max_multiplier << 8) | max_voltage;
387        f_table[2].frequency = CPUFREQ_TABLE_END;
388    } else {
389        k = 0;
390        step = ((max_voltage - min_voltage) * 256)
391            / (max_multiplier - min_multiplier);
392        for (i = min_multiplier; i <= max_multiplier; i++) {
393            voltage = (k * step) / 256 + min_voltage;
394            f_table[k].frequency = fsb * i;
395            f_table[k].index = (i << 8) | voltage;
396            k++;
397        }
398        f_table[k].frequency = CPUFREQ_TABLE_END;
399    }
400
401    policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
402    policy->cur = fsb * current_multiplier;
403
404    ret = cpufreq_frequency_table_cpuinfo(policy, &centaur->freq_table[0]);
405    if (ret) {
406        kfree(centaur);
407        return ret;
408    }
409
410    cpufreq_frequency_table_get_attr(&centaur->freq_table[0], policy->cpu);
411    return 0;
412}
413
414static int eps_cpu_exit(struct cpufreq_policy *policy)
415{
416    unsigned int cpu = policy->cpu;
417
418    /* Bye */
419    cpufreq_frequency_table_put_attr(policy->cpu);
420    kfree(eps_cpu[cpu]);
421    eps_cpu[cpu] = NULL;
422    return 0;
423}
424
425static struct freq_attr *eps_attr[] = {
426    &cpufreq_freq_attr_scaling_available_freqs,
427    NULL,
428};
429
430static struct cpufreq_driver eps_driver = {
431    .verify = eps_verify,
432    .target = eps_target,
433    .init = eps_cpu_init,
434    .exit = eps_cpu_exit,
435    .get = eps_get,
436    .name = "e_powersaver",
437    .owner = THIS_MODULE,
438    .attr = eps_attr,
439};
440
441
442/* This driver will work only on Centaur C7 processors with
443 * Enhanced SpeedStep/PowerSaver registers */
444static const struct x86_cpu_id eps_cpu_id[] = {
445    { X86_VENDOR_CENTAUR, 6, X86_MODEL_ANY, X86_FEATURE_EST },
446    {}
447};
448MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
449
450static int __init eps_init(void)
451{
452    if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
453        return -ENODEV;
454    if (cpufreq_register_driver(&eps_driver))
455        return -EINVAL;
456    return 0;
457}
458
459static void __exit eps_exit(void)
460{
461    cpufreq_unregister_driver(&eps_driver);
462}
463
464/* Allow user to overclock his machine or to change frequency to higher after
465 * unloading module */
466module_param(freq_failsafe_off, int, 0644);
467MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
468module_param(voltage_failsafe_off, int, 0644);
469MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
470#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
471module_param(ignore_acpi_limit, int, 0644);
472MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
473#endif
474module_param(set_max_voltage, int, 0644);
475MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
476
477MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
478MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
479MODULE_LICENSE("GPL");
480
481module_init(eps_init);
482module_exit(eps_exit);
483

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