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Diffstat (limited to 'arch/i386/kernel/cpu/cpufreq/e_powersaver.c')
-rw-r--r--arch/i386/kernel/cpu/cpufreq/e_powersaver.c334
1 files changed, 334 insertions, 0 deletions
diff --git a/arch/i386/kernel/cpu/cpufreq/e_powersaver.c b/arch/i386/kernel/cpu/cpufreq/e_powersaver.c
new file mode 100644
index 00000000000..3243725f80c
--- /dev/null
+++ b/arch/i386/kernel/cpu/cpufreq/e_powersaver.c
@@ -0,0 +1,334 @@
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
16#include <asm/msr.h>
17#include <asm/tsc.h>
18#include <asm/timex.h>
19#include <asm/io.h>
20#include <asm/delay.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
27struct eps_cpu_data {
28 u32 fsb;
29 struct cpufreq_frequency_table freq_table[];
30};
31
32static struct eps_cpu_data *eps_cpu[NR_CPUS];
33
34
35static unsigned int eps_get(unsigned int cpu)
36{
37 struct eps_cpu_data *centaur;
38 u32 lo, hi;
39
40 if (cpu)
41 return 0;
42 centaur = eps_cpu[cpu];
43 if (centaur == NULL)
44 return 0;
45
46 /* Return current frequency */
47 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
48 return centaur->fsb * ((lo >> 8) & 0xff);
49}
50
51static int eps_set_state(struct eps_cpu_data *centaur,
52 unsigned int cpu,
53 u32 dest_state)
54{
55 struct cpufreq_freqs freqs;
56 u32 lo, hi;
57 int err = 0;
58 int i;
59
60 freqs.old = eps_get(cpu);
61 freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
62 freqs.cpu = cpu;
63 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
64
65 /* Wait while CPU is busy */
66 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
67 i = 0;
68 while (lo & ((1 << 16) | (1 << 17))) {
69 udelay(16);
70 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
71 i++;
72 if (unlikely(i > 64)) {
73 err = -ENODEV;
74 goto postchange;
75 }
76 }
77 /* Set new multiplier and voltage */
78 wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
79 /* Wait until transition end */
80 i = 0;
81 do {
82 udelay(16);
83 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
84 i++;
85 if (unlikely(i > 64)) {
86 err = -ENODEV;
87 goto postchange;
88 }
89 } while (lo & ((1 << 16) | (1 << 17)));
90
91 /* Return current frequency */
92postchange:
93 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
94 freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
95
96 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
97 return err;
98}
99
100static int eps_target(struct cpufreq_policy *policy,
101 unsigned int target_freq,
102 unsigned int relation)
103{
104 struct eps_cpu_data *centaur;
105 unsigned int newstate = 0;
106 unsigned int cpu = policy->cpu;
107 unsigned int dest_state;
108 int ret;
109
110 if (unlikely(eps_cpu[cpu] == NULL))
111 return -ENODEV;
112 centaur = eps_cpu[cpu];
113
114 if (unlikely(cpufreq_frequency_table_target(policy,
115 &eps_cpu[cpu]->freq_table[0],
116 target_freq,
117 relation,
118 &newstate))) {
119 return -EINVAL;
120 }
121
122 /* Make frequency transition */
123 dest_state = centaur->freq_table[newstate].index & 0xffff;
124 ret = eps_set_state(centaur, cpu, dest_state);
125 if (ret)
126 printk(KERN_ERR "eps: Timeout!\n");
127 return ret;
128}
129
130static int eps_verify(struct cpufreq_policy *policy)
131{
132 return cpufreq_frequency_table_verify(policy,
133 &eps_cpu[policy->cpu]->freq_table[0]);
134}
135
136static int eps_cpu_init(struct cpufreq_policy *policy)
137{
138 unsigned int i;
139 u32 lo, hi;
140 u64 val;
141 u8 current_multiplier, current_voltage;
142 u8 max_multiplier, max_voltage;
143 u8 min_multiplier, min_voltage;
144 u8 brand;
145 u32 fsb;
146 struct eps_cpu_data *centaur;
147 struct cpufreq_frequency_table *f_table;
148 int k, step, voltage;
149 int ret;
150 int states;
151
152 if (policy->cpu != 0)
153 return -ENODEV;
154
155 /* Check brand */
156 printk("eps: Detected VIA ");
157 rdmsr(0x1153, lo, hi);
158 brand = (((lo >> 2) ^ lo) >> 18) & 3;
159 switch(brand) {
160 case EPS_BRAND_C7M:
161 printk("C7-M\n");
162 break;
163 case EPS_BRAND_C7:
164 printk("C7\n");
165 break;
166 case EPS_BRAND_EDEN:
167 printk("Eden\n");
168 break;
169 case EPS_BRAND_C3:
170 printk("C3\n");
171 return -ENODEV;
172 break;
173 }
174 /* Enable Enhanced PowerSaver */
175 rdmsrl(MSR_IA32_MISC_ENABLE, val);
176 if (!(val & 1 << 16)) {
177 val |= 1 << 16;
178 wrmsrl(MSR_IA32_MISC_ENABLE, val);
179 /* Can be locked at 0 */
180 rdmsrl(MSR_IA32_MISC_ENABLE, val);
181 if (!(val & 1 << 16)) {
182 printk("eps: Can't enable Enhanced PowerSaver\n");
183 return -ENODEV;
184 }
185 }
186
187 /* Print voltage and multiplier */
188 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
189 current_voltage = lo & 0xff;
190 printk("eps: Current voltage = %dmV\n", current_voltage * 16 + 700);
191 current_multiplier = (lo >> 8) & 0xff;
192 printk("eps: Current multiplier = %d\n", current_multiplier);
193
194 /* Print limits */
195 max_voltage = hi & 0xff;
196 printk("eps: Highest voltage = %dmV\n", max_voltage * 16 + 700);
197 max_multiplier = (hi >> 8) & 0xff;
198 printk("eps: Highest multiplier = %d\n", max_multiplier);
199 min_voltage = (hi >> 16) & 0xff;
200 printk("eps: Lowest voltage = %dmV\n", min_voltage * 16 + 700);
201 min_multiplier = (hi >> 24) & 0xff;
202 printk("eps: Lowest multiplier = %d\n", min_multiplier);
203
204 /* Sanity checks */
205 if (current_multiplier == 0 || max_multiplier == 0
206 || min_multiplier == 0)
207 return -EINVAL;
208 if (current_multiplier > max_multiplier
209 || max_multiplier <= min_multiplier)
210 return -EINVAL;
211 if (current_voltage > 0x1c || max_voltage > 0x1c)
212 return -EINVAL;
213 if (max_voltage < min_voltage)
214 return -EINVAL;
215
216 /* Calc FSB speed */
217 fsb = cpu_khz / current_multiplier;
218 /* Calc number of p-states supported */
219 if (brand == EPS_BRAND_C7M)
220 states = max_multiplier - min_multiplier + 1;
221 else
222 states = 2;
223
224 /* Allocate private data and frequency table for current cpu */
225 centaur = kzalloc(sizeof(struct eps_cpu_data)
226 + (states + 1) * sizeof(struct cpufreq_frequency_table),
227 GFP_KERNEL);
228 if (!centaur)
229 return -ENOMEM;
230 eps_cpu[0] = centaur;
231
232 /* Copy basic values */
233 centaur->fsb = fsb;
234
235 /* Fill frequency and MSR value table */
236 f_table = &centaur->freq_table[0];
237 if (brand == EPS_BRAND_EDEN) {
238 f_table[0].frequency = fsb * min_multiplier;
239 f_table[0].index = (min_multiplier << 8) | min_voltage;
240 f_table[1].frequency = fsb * max_multiplier;
241 f_table[1].index = (max_multiplier << 8) | max_voltage;
242 f_table[2].frequency = CPUFREQ_TABLE_END;
243 } else {
244 k = 0;
245 step = ((max_voltage - min_voltage) * 256)
246 / (max_multiplier - min_multiplier);
247 for (i = min_multiplier; i <= max_multiplier; i++) {
248 voltage = (k * step) / 256 + min_voltage;
249 f_table[k].frequency = fsb * i;
250 f_table[k].index = (i << 8) | voltage;
251 k++;
252 }
253 f_table[k].frequency = CPUFREQ_TABLE_END;
254 }
255
256 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
257 policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
258 policy->cur = fsb * current_multiplier;
259
260 ret = cpufreq_frequency_table_cpuinfo(policy, &centaur->freq_table[0]);
261 if (ret) {
262 kfree(centaur);
263 return ret;
264 }
265
266 cpufreq_frequency_table_get_attr(&centaur->freq_table[0], policy->cpu);
267 return 0;
268}
269
270static int eps_cpu_exit(struct cpufreq_policy *policy)
271{
272 unsigned int cpu = policy->cpu;
273 struct eps_cpu_data *centaur;
274 u32 lo, hi;
275
276 if (eps_cpu[cpu] == NULL)
277 return -ENODEV;
278 centaur = eps_cpu[cpu];
279
280 /* Get max frequency */
281 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
282 /* Set max frequency */
283 eps_set_state(centaur, cpu, hi & 0xffff);
284 /* Bye */
285 cpufreq_frequency_table_put_attr(policy->cpu);
286 kfree(eps_cpu[cpu]);
287 eps_cpu[cpu] = NULL;
288 return 0;
289}
290
291static struct freq_attr* eps_attr[] = {
292 &cpufreq_freq_attr_scaling_available_freqs,
293 NULL,
294};
295
296static struct cpufreq_driver eps_driver = {
297 .verify = eps_verify,
298 .target = eps_target,
299 .init = eps_cpu_init,
300 .exit = eps_cpu_exit,
301 .get = eps_get,
302 .name = "e_powersaver",
303 .owner = THIS_MODULE,
304 .attr = eps_attr,
305};
306
307static int __init eps_init(void)
308{
309 struct cpuinfo_x86 *c = cpu_data;
310
311 /* This driver will work only on Centaur C7 processors with
312 * Enhanced SpeedStep/PowerSaver registers */
313 if (c->x86_vendor != X86_VENDOR_CENTAUR
314 || c->x86 != 6 || c->x86_model != 10)
315 return -ENODEV;
316 if (!cpu_has(c, X86_FEATURE_EST))
317 return -ENODEV;
318
319 if (cpufreq_register_driver(&eps_driver))
320 return -EINVAL;
321 return 0;
322}
323
324static void __exit eps_exit(void)
325{
326 cpufreq_unregister_driver(&eps_driver);
327}
328
329MODULE_AUTHOR("Rafał Bilski <rafalbilski@interia.pl>");
330MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
331MODULE_LICENSE("GPL");
332
333module_init(eps_init);
334module_exit(eps_exit);
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