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(*eps_acpi_cpu_perf),
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			 struct cpufreq_policy *policy,
108			 u32 dest_state)
109{
110	u32 lo, hi;
111	int i;
112
113	/* Wait while CPU is busy */
114	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
115	i = 0;
116	while (lo & ((1 << 16) | (1 << 17))) {
117		udelay(16);
118		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
119		i++;
120		if (unlikely(i > 64)) {
121			return -ENODEV;
122		}
123	}
124	/* Set new multiplier and voltage */
125	wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
126	/* Wait until transition end */
127	i = 0;
128	do {
129		udelay(16);
130		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
131		i++;
132		if (unlikely(i > 64)) {
133			return -ENODEV;
134		}
135	} while (lo & ((1 << 16) | (1 << 17)));
136
137#ifdef DEBUG
138	{
139	u8 current_multiplier, current_voltage;
140
141	/* Print voltage and multiplier */
142	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
143	current_voltage = lo & 0xff;
144	printk(KERN_INFO "eps: Current voltage = %dmV\n",
145		current_voltage * 16 + 700);
146	current_multiplier = (lo >> 8) & 0xff;
147	printk(KERN_INFO "eps: Current multiplier = %d\n",
148		current_multiplier);
149	}
150#endif
151	return 0;
152}
153
154static int eps_target(struct cpufreq_policy *policy, unsigned int index)
155{
156	struct eps_cpu_data *centaur;
157	unsigned int cpu = policy->cpu;
158	unsigned int dest_state;
159	int ret;
160
161	if (unlikely(eps_cpu[cpu] == NULL))
162		return -ENODEV;
163	centaur = eps_cpu[cpu];
164
165	/* Make frequency transition */
166	dest_state = centaur->freq_table[index].driver_data & 0xffff;
167	ret = eps_set_state(centaur, policy, dest_state);
168	if (ret)
169		printk(KERN_ERR "eps: Timeout!\n");
170	return ret;
171}
172
173static int eps_cpu_init(struct cpufreq_policy *policy)
174{
175	unsigned int i;
176	u32 lo, hi;
177	u64 val;
178	u8 current_multiplier, current_voltage;
179	u8 max_multiplier, max_voltage;
180	u8 min_multiplier, min_voltage;
181	u8 brand = 0;
182	u32 fsb;
183	struct eps_cpu_data *centaur;
184	struct cpuinfo_x86 *c = &cpu_data(0);
185	struct cpufreq_frequency_table *f_table;
186	int k, step, voltage;
187	int ret;
188	int states;
189#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
190	unsigned int limit;
191#endif
192
193	if (policy->cpu != 0)
194		return -ENODEV;
195
196	/* Check brand */
197	printk(KERN_INFO "eps: Detected VIA ");
198
199	switch (c->x86_model) {
200	case 10:
201		rdmsr(0x1153, lo, hi);
202		brand = (((lo >> 2) ^ lo) >> 18) & 3;
203		printk(KERN_CONT "Model A ");
204		break;
205	case 13:
206		rdmsr(0x1154, lo, hi);
207		brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
208		printk(KERN_CONT "Model D ");
209		break;
210	}
211
212	switch (brand) {
213	case EPS_BRAND_C7M:
214		printk(KERN_CONT "C7-M\n");
215		break;
216	case EPS_BRAND_C7:
217		printk(KERN_CONT "C7\n");
218		break;
219	case EPS_BRAND_EDEN:
220		printk(KERN_CONT "Eden\n");
221		break;
222	case EPS_BRAND_C7D:
223		printk(KERN_CONT "C7-D\n");
224		break;
225	case EPS_BRAND_C3:
226		printk(KERN_CONT "C3\n");
227		return -ENODEV;
228		break;
229	}
230	/* Enable Enhanced PowerSaver */
231	rdmsrl(MSR_IA32_MISC_ENABLE, val);
232	if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
233		val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
234		wrmsrl(MSR_IA32_MISC_ENABLE, val);
235		/* Can be locked at 0 */
236		rdmsrl(MSR_IA32_MISC_ENABLE, val);
237		if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
238			printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
239			return -ENODEV;
240		}
241	}
242
243	/* Print voltage and multiplier */
244	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
245	current_voltage = lo & 0xff;
246	printk(KERN_INFO "eps: Current voltage = %dmV\n",
247			current_voltage * 16 + 700);
248	current_multiplier = (lo >> 8) & 0xff;
249	printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
250
251	/* Print limits */
252	max_voltage = hi & 0xff;
253	printk(KERN_INFO "eps: Highest voltage = %dmV\n",
254			max_voltage * 16 + 700);
255	max_multiplier = (hi >> 8) & 0xff;
256	printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
257	min_voltage = (hi >> 16) & 0xff;
258	printk(KERN_INFO "eps: Lowest voltage = %dmV\n",
259			min_voltage * 16 + 700);
260	min_multiplier = (hi >> 24) & 0xff;
261	printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
262
263	/* Sanity checks */
264	if (current_multiplier == 0 || max_multiplier == 0
265	    || min_multiplier == 0)
266		return -EINVAL;
267	if (current_multiplier > max_multiplier
268	    || max_multiplier <= min_multiplier)
269		return -EINVAL;
270	if (current_voltage > 0x1f || max_voltage > 0x1f)
271		return -EINVAL;
272	if (max_voltage < min_voltage
273	    || current_voltage < min_voltage
274	    || current_voltage > max_voltage)
275		return -EINVAL;
276
277	/* Check for systems using underclocked CPU */
278	if (!freq_failsafe_off && max_multiplier != current_multiplier) {
279		printk(KERN_INFO "eps: Your processor is running at different "
280			"frequency then its maximum. Aborting.\n");
281		printk(KERN_INFO "eps: You can use freq_failsafe_off option "
282			"to disable this check.\n");
283		return -EINVAL;
284	}
285	if (!voltage_failsafe_off && max_voltage != current_voltage) {
286		printk(KERN_INFO "eps: Your processor is running at different "
287			"voltage then its maximum. Aborting.\n");
288		printk(KERN_INFO "eps: You can use voltage_failsafe_off "
289			"option to disable this check.\n");
290		return -EINVAL;
291	}
292
293	/* Calc FSB speed */
294	fsb = cpu_khz / current_multiplier;
295
296#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
297	/* Check for ACPI processor speed limit */
298	if (!ignore_acpi_limit && !eps_acpi_init()) {
299		if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
300			printk(KERN_INFO "eps: ACPI limit %u.%uGHz\n",
301				limit/1000000,
302				(limit%1000000)/10000);
303			eps_acpi_exit(policy);
304			/* Check if max_multiplier is in BIOS limits */
305			if (limit && max_multiplier * fsb > limit) {
306				printk(KERN_INFO "eps: Aborting.\n");
307				return -EINVAL;
308			}
309		}
310	}
311#endif
312
313	/* Allow user to set lower maximum voltage then that reported
314	 * by processor */
315	if (brand == EPS_BRAND_C7M && set_max_voltage) {
316		u32 v;
317
318		/* Change mV to something hardware can use */
319		v = (set_max_voltage - 700) / 16;
320		/* Check if voltage is within limits */
321		if (v >= min_voltage && v <= max_voltage) {
322			printk(KERN_INFO "eps: Setting %dmV as maximum.\n",
323				v * 16 + 700);
324			max_voltage = v;
325		}
326	}
327
328	/* Calc number of p-states supported */
329	if (brand == EPS_BRAND_C7M)
330		states = max_multiplier - min_multiplier + 1;
331	else
332		states = 2;
333
334	/* Allocate private data and frequency table for current cpu */
335	centaur = kzalloc(sizeof(*centaur)
336		    + (states + 1) * sizeof(struct cpufreq_frequency_table),
337		    GFP_KERNEL);
338	if (!centaur)
339		return -ENOMEM;
340	eps_cpu[0] = centaur;
341
342	/* Copy basic values */
343	centaur->fsb = fsb;
344#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
345	centaur->bios_limit = limit;
346#endif
347
348	/* Fill frequency and MSR value table */
349	f_table = &centaur->freq_table[0];
350	if (brand != EPS_BRAND_C7M) {
351		f_table[0].frequency = fsb * min_multiplier;
352		f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
353		f_table[1].frequency = fsb * max_multiplier;
354		f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
355		f_table[2].frequency = CPUFREQ_TABLE_END;
356	} else {
357		k = 0;
358		step = ((max_voltage - min_voltage) * 256)
359			/ (max_multiplier - min_multiplier);
360		for (i = min_multiplier; i <= max_multiplier; i++) {
361			voltage = (k * step) / 256 + min_voltage;
362			f_table[k].frequency = fsb * i;
363			f_table[k].driver_data = (i << 8) | voltage;
364			k++;
365		}
366		f_table[k].frequency = CPUFREQ_TABLE_END;
367	}
368
369	policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
370
371	ret = cpufreq_table_validate_and_show(policy, &centaur->freq_table[0]);
372	if (ret) {
373		kfree(centaur);
374		return ret;
375	}
376
377	return 0;
378}
379
380static int eps_cpu_exit(struct cpufreq_policy *policy)
381{
382	unsigned int cpu = policy->cpu;
383
384	/* Bye */
385	kfree(eps_cpu[cpu]);
386	eps_cpu[cpu] = NULL;
387	return 0;
388}
389
390static struct cpufreq_driver eps_driver = {
391	.verify		= cpufreq_generic_frequency_table_verify,
392	.target_index	= eps_target,
393	.init		= eps_cpu_init,
394	.exit		= eps_cpu_exit,
395	.get		= eps_get,
396	.name		= "e_powersaver",
397	.attr		= cpufreq_generic_attr,
398};
399
400
401/* This driver will work only on Centaur C7 processors with
402 * Enhanced SpeedStep/PowerSaver registers */
403static const struct x86_cpu_id eps_cpu_id[] = {
404	{ X86_VENDOR_CENTAUR, 6, X86_MODEL_ANY, X86_FEATURE_EST },
405	{}
406};
407MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
408
409static int __init eps_init(void)
410{
411	if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
412		return -ENODEV;
413	if (cpufreq_register_driver(&eps_driver))
414		return -EINVAL;
415	return 0;
416}
417
418static void __exit eps_exit(void)
419{
420	cpufreq_unregister_driver(&eps_driver);
421}
422
423/* Allow user to overclock his machine or to change frequency to higher after
424 * unloading module */
425module_param(freq_failsafe_off, int, 0644);
426MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
427module_param(voltage_failsafe_off, int, 0644);
428MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
429#if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
430module_param(ignore_acpi_limit, int, 0644);
431MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
432#endif
433module_param(set_max_voltage, int, 0644);
434MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
435
436MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
437MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
438MODULE_LICENSE("GPL");
439
440module_init(eps_init);
441module_exit(eps_exit);
442