[CPUFREQ] Remove pointless reinitialisations in acpi-cpufreq
[linux-2.6.git] / arch / i386 / kernel / cpu / cpufreq / acpi-cpufreq.c
1 /*
2  * acpi-cpufreq.c - ACPI Processor P-States Driver ($Revision: 1.3 $)
3  *
4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
6  *  Copyright (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
7  *
8  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9  *
10  *  This program is free software; you can redistribute it and/or modify
11  *  it under the terms of the GNU General Public License as published by
12  *  the Free Software Foundation; either version 2 of the License, or (at
13  *  your option) any later version.
14  *
15  *  This program is distributed in the hope that it will be useful, but
16  *  WITHOUT ANY WARRANTY; without even the implied warranty of
17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  *  General Public License for more details.
19  *
20  *  You should have received a copy of the GNU General Public License along
21  *  with this program; if not, write to the Free Software Foundation, Inc.,
22  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
23  *
24  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
25  */
26
27 #include <linux/config.h>
28 #include <linux/kernel.h>
29 #include <linux/module.h>
30 #include <linux/init.h>
31 #include <linux/cpufreq.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/compiler.h>
35 #include <linux/sched.h>        /* current */
36 #include <asm/io.h>
37 #include <asm/delay.h>
38 #include <asm/uaccess.h>
39
40 #include <linux/acpi.h>
41 #include <acpi/processor.h>
42
43 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "acpi-cpufreq", msg)
44
45 MODULE_AUTHOR("Paul Diefenbaugh, Dominik Brodowski");
46 MODULE_DESCRIPTION("ACPI Processor P-States Driver");
47 MODULE_LICENSE("GPL");
48
49
50 struct cpufreq_acpi_io {
51         struct acpi_processor_performance       acpi_data;
52         struct cpufreq_frequency_table          *freq_table;
53         unsigned int                            resume;
54 };
55
56 static struct cpufreq_acpi_io   *acpi_io_data[NR_CPUS];
57
58 static struct cpufreq_driver acpi_cpufreq_driver;
59
60 static unsigned int acpi_pstate_strict;
61
62 static int
63 acpi_processor_write_port(
64         u16     port,
65         u8      bit_width,
66         u32     value)
67 {
68         if (bit_width <= 8) {
69                 outb(value, port);
70         } else if (bit_width <= 16) {
71                 outw(value, port);
72         } else if (bit_width <= 32) {
73                 outl(value, port);
74         } else {
75                 return -ENODEV;
76         }
77         return 0;
78 }
79
80 static int
81 acpi_processor_read_port(
82         u16     port,
83         u8      bit_width,
84         u32     *ret)
85 {
86         *ret = 0;
87         if (bit_width <= 8) {
88                 *ret = inb(port);
89         } else if (bit_width <= 16) {
90                 *ret = inw(port);
91         } else if (bit_width <= 32) {
92                 *ret = inl(port);
93         } else {
94                 return -ENODEV;
95         }
96         return 0;
97 }
98
99 static int
100 acpi_processor_set_performance (
101         struct cpufreq_acpi_io  *data,
102         unsigned int            cpu,
103         int                     state)
104 {
105         u16                     port = 0;
106         u8                      bit_width = 0;
107         int                     ret;
108         u32                     value = 0;
109         int                     i = 0;
110         struct cpufreq_freqs    cpufreq_freqs;
111         cpumask_t               saved_mask;
112         int                     retval;
113
114         dprintk("acpi_processor_set_performance\n");
115
116         /*
117          * TBD: Use something other than set_cpus_allowed.
118          * As set_cpus_allowed is a bit racy, 
119          * with any other set_cpus_allowed for this process.
120          */
121         saved_mask = current->cpus_allowed;
122         set_cpus_allowed(current, cpumask_of_cpu(cpu));
123         if (smp_processor_id() != cpu) {
124                 return (-EAGAIN);
125         }
126         
127         if (state == data->acpi_data.state) {
128                 if (unlikely(data->resume)) {
129                         dprintk("Called after resume, resetting to P%d\n", state);
130                         data->resume = 0;
131                 } else {
132                         dprintk("Already at target state (P%d)\n", state);
133                         retval = 0;
134                         goto migrate_end;
135                 }
136         }
137
138         dprintk("Transitioning from P%d to P%d\n",
139                 data->acpi_data.state, state);
140
141         /* cpufreq frequency struct */
142         cpufreq_freqs.cpu = cpu;
143         cpufreq_freqs.old = data->freq_table[data->acpi_data.state].frequency;
144         cpufreq_freqs.new = data->freq_table[state].frequency;
145
146         /* notify cpufreq */
147         cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
148
149         /*
150          * First we write the target state's 'control' value to the
151          * control_register.
152          */
153
154         port = data->acpi_data.control_register.address;
155         bit_width = data->acpi_data.control_register.bit_width;
156         value = (u32) data->acpi_data.states[state].control;
157
158         dprintk("Writing 0x%08x to port 0x%04x\n", value, port);
159
160         ret = acpi_processor_write_port(port, bit_width, value);
161         if (ret) {
162                 dprintk("Invalid port width 0x%04x\n", bit_width);
163                 retval = ret;
164                 goto migrate_end;
165         }
166
167         /*
168          * Assume the write went through when acpi_pstate_strict is not used.
169          * As read status_register is an expensive operation and there 
170          * are no specific error cases where an IO port write will fail.
171          */
172         if (acpi_pstate_strict) {
173                 /* Then we read the 'status_register' and compare the value 
174                  * with the target state's 'status' to make sure the 
175                  * transition was successful.
176                  * Note that we'll poll for up to 1ms (100 cycles of 10us) 
177                  * before giving up.
178                  */
179
180                 port = data->acpi_data.status_register.address;
181                 bit_width = data->acpi_data.status_register.bit_width;
182
183                 dprintk("Looking for 0x%08x from port 0x%04x\n",
184                         (u32) data->acpi_data.states[state].status, port);
185
186                 for (i=0; i<100; i++) {
187                         ret = acpi_processor_read_port(port, bit_width, &value);
188                         if (ret) {      
189                                 dprintk("Invalid port width 0x%04x\n", bit_width);
190                                 retval = ret;
191                                 goto migrate_end;
192                         }
193                         if (value == (u32) data->acpi_data.states[state].status)
194                                 break;
195                         udelay(10);
196                 }
197         } else {
198                 value = (u32) data->acpi_data.states[state].status;
199         }
200
201         /* notify cpufreq */
202         cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
203
204         if (unlikely(value != (u32) data->acpi_data.states[state].status)) {
205                 unsigned int tmp = cpufreq_freqs.new;
206                 cpufreq_freqs.new = cpufreq_freqs.old;
207                 cpufreq_freqs.old = tmp;
208                 cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
209                 cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
210                 printk(KERN_WARNING "acpi-cpufreq: Transition failed\n");
211                 retval = -ENODEV;
212                 goto migrate_end;
213         }
214
215         dprintk("Transition successful after %d microseconds\n", i * 10);
216
217         data->acpi_data.state = state;
218
219         retval = 0;
220 migrate_end:
221         set_cpus_allowed(current, saved_mask);
222         return (retval);
223 }
224
225
226 static int
227 acpi_cpufreq_target (
228         struct cpufreq_policy   *policy,
229         unsigned int target_freq,
230         unsigned int relation)
231 {
232         struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
233         unsigned int next_state = 0;
234         unsigned int result = 0;
235
236         dprintk("acpi_cpufreq_setpolicy\n");
237
238         result = cpufreq_frequency_table_target(policy,
239                         data->freq_table,
240                         target_freq,
241                         relation,
242                         &next_state);
243         if (result)
244                 return (result);
245
246         result = acpi_processor_set_performance (data, policy->cpu, next_state);
247
248         return (result);
249 }
250
251
252 static int
253 acpi_cpufreq_verify (
254         struct cpufreq_policy   *policy)
255 {
256         unsigned int result = 0;
257         struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
258
259         dprintk("acpi_cpufreq_verify\n");
260
261         result = cpufreq_frequency_table_verify(policy, 
262                         data->freq_table);
263
264         return (result);
265 }
266
267
268 static unsigned long
269 acpi_cpufreq_guess_freq (
270         struct cpufreq_acpi_io  *data,
271         unsigned int            cpu)
272 {
273         if (cpu_khz) {
274                 /* search the closest match to cpu_khz */
275                 unsigned int i;
276                 unsigned long freq;
277                 unsigned long freqn = data->acpi_data.states[0].core_frequency * 1000;
278
279                 for (i=0; i < (data->acpi_data.state_count - 1); i++) {
280                         freq = freqn;
281                         freqn = data->acpi_data.states[i+1].core_frequency * 1000;
282                         if ((2 * cpu_khz) > (freqn + freq)) {
283                                 data->acpi_data.state = i;
284                                 return (freq);
285                         }
286                 }
287                 data->acpi_data.state = data->acpi_data.state_count - 1;
288                 return (freqn);
289         } else
290                 /* assume CPU is at P0... */
291                 data->acpi_data.state = 0;
292                 return data->acpi_data.states[0].core_frequency * 1000;
293         
294 }
295
296
297 static int
298 acpi_cpufreq_cpu_init (
299         struct cpufreq_policy   *policy)
300 {
301         unsigned int            i;
302         unsigned int            cpu = policy->cpu;
303         struct cpufreq_acpi_io  *data;
304         unsigned int            result = 0;
305         struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
306
307         dprintk("acpi_cpufreq_cpu_init\n");
308
309         data = kzalloc(sizeof(struct cpufreq_acpi_io), GFP_KERNEL);
310         if (!data)
311                 return (-ENOMEM);
312
313         acpi_io_data[cpu] = data;
314
315         result = acpi_processor_register_performance(&data->acpi_data, cpu);
316
317         if (result)
318                 goto err_free;
319
320         if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {
321                 acpi_cpufreq_driver.flags |= CPUFREQ_CONST_LOOPS;
322         }
323
324         /* capability check */
325         if (data->acpi_data.state_count <= 1) {
326                 dprintk("No P-States\n");
327                 result = -ENODEV;
328                 goto err_unreg;
329         }
330         if ((data->acpi_data.control_register.space_id != ACPI_ADR_SPACE_SYSTEM_IO) ||
331             (data->acpi_data.status_register.space_id != ACPI_ADR_SPACE_SYSTEM_IO)) {
332                 dprintk("Unsupported address space [%d, %d]\n",
333                         (u32) (data->acpi_data.control_register.space_id),
334                         (u32) (data->acpi_data.status_register.space_id));
335                 result = -ENODEV;
336                 goto err_unreg;
337         }
338
339         /* alloc freq_table */
340         data->freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) * (data->acpi_data.state_count + 1), GFP_KERNEL);
341         if (!data->freq_table) {
342                 result = -ENOMEM;
343                 goto err_unreg;
344         }
345
346         /* detect transition latency */
347         policy->cpuinfo.transition_latency = 0;
348         for (i=0; i<data->acpi_data.state_count; i++) {
349                 if ((data->acpi_data.states[i].transition_latency * 1000) > policy->cpuinfo.transition_latency)
350                         policy->cpuinfo.transition_latency = data->acpi_data.states[i].transition_latency * 1000;
351         }
352         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
353
354         /* The current speed is unknown and not detectable by ACPI...  */
355         policy->cur = acpi_cpufreq_guess_freq(data, policy->cpu);
356
357         /* table init */
358         for (i=0; i<=data->acpi_data.state_count; i++)
359         {
360                 data->freq_table[i].index = i;
361                 if (i<data->acpi_data.state_count)
362                         data->freq_table[i].frequency = data->acpi_data.states[i].core_frequency * 1000;
363                 else
364                         data->freq_table[i].frequency = CPUFREQ_TABLE_END;
365         }
366
367         result = cpufreq_frequency_table_cpuinfo(policy, data->freq_table);
368         if (result) {
369                 goto err_freqfree;
370         }
371
372         /* notify BIOS that we exist */
373         acpi_processor_notify_smm(THIS_MODULE);
374
375         printk(KERN_INFO "acpi-cpufreq: CPU%u - ACPI performance management activated.\n",
376                cpu);
377         for (i = 0; i < data->acpi_data.state_count; i++)
378                 dprintk("     %cP%d: %d MHz, %d mW, %d uS\n",
379                         (i == data->acpi_data.state?'*':' '), i,
380                         (u32) data->acpi_data.states[i].core_frequency,
381                         (u32) data->acpi_data.states[i].power,
382                         (u32) data->acpi_data.states[i].transition_latency);
383
384         cpufreq_frequency_table_get_attr(data->freq_table, policy->cpu);
385         
386         /*
387          * the first call to ->target() should result in us actually
388          * writing something to the appropriate registers.
389          */
390         data->resume = 1;
391         
392         return (result);
393
394  err_freqfree:
395         kfree(data->freq_table);
396  err_unreg:
397         acpi_processor_unregister_performance(&data->acpi_data, cpu);
398  err_free:
399         kfree(data);
400         acpi_io_data[cpu] = NULL;
401
402         return (result);
403 }
404
405
406 static int
407 acpi_cpufreq_cpu_exit (
408         struct cpufreq_policy   *policy)
409 {
410         struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
411
412
413         dprintk("acpi_cpufreq_cpu_exit\n");
414
415         if (data) {
416                 cpufreq_frequency_table_put_attr(policy->cpu);
417                 acpi_io_data[policy->cpu] = NULL;
418                 acpi_processor_unregister_performance(&data->acpi_data, policy->cpu);
419                 kfree(data);
420         }
421
422         return (0);
423 }
424
425 static int
426 acpi_cpufreq_resume (
427         struct cpufreq_policy   *policy)
428 {
429         struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
430
431
432         dprintk("acpi_cpufreq_resume\n");
433
434         data->resume = 1;
435
436         return (0);
437 }
438
439
440 static struct freq_attr* acpi_cpufreq_attr[] = {
441         &cpufreq_freq_attr_scaling_available_freqs,
442         NULL,
443 };
444
445 static struct cpufreq_driver acpi_cpufreq_driver = {
446         .verify         = acpi_cpufreq_verify,
447         .target         = acpi_cpufreq_target,
448         .init           = acpi_cpufreq_cpu_init,
449         .exit           = acpi_cpufreq_cpu_exit,
450         .resume         = acpi_cpufreq_resume,
451         .name           = "acpi-cpufreq",
452         .owner          = THIS_MODULE,
453         .attr           = acpi_cpufreq_attr,
454 };
455
456
457 static int __init
458 acpi_cpufreq_init (void)
459 {
460         int                     result = 0;
461
462         dprintk("acpi_cpufreq_init\n");
463
464         result = cpufreq_register_driver(&acpi_cpufreq_driver);
465         
466         return (result);
467 }
468
469
470 static void __exit
471 acpi_cpufreq_exit (void)
472 {
473         dprintk("acpi_cpufreq_exit\n");
474
475         cpufreq_unregister_driver(&acpi_cpufreq_driver);
476
477         return;
478 }
479
480 module_param(acpi_pstate_strict, uint, 0644);
481 MODULE_PARM_DESC(acpi_pstate_strict, "value 0 or non-zero. non-zero -> strict ACPI checks are performed during frequency changes.");
482
483 late_initcall(acpi_cpufreq_init);
484 module_exit(acpi_cpufreq_exit);
485
486 MODULE_ALIAS("acpi");