Merge branch 'for-linus-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/mason...
[linux-2.6-block.git] / drivers / cpufreq / speedstep-smi.c
1 /*
2  * Intel SpeedStep SMI driver.
3  *
4  * (C) 2003  Hiroshi Miura <miura@da-cha.org>
5  *
6  *  Licensed under the terms of the GNU GPL License version 2.
7  *
8  */
9
10
11 /*********************************************************************
12  *                        SPEEDSTEP - DEFINITIONS                    *
13  *********************************************************************/
14
15 #define pr_fmt(fmt) "cpufreq: " fmt
16
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/init.h>
21 #include <linux/cpufreq.h>
22 #include <linux/delay.h>
23 #include <linux/io.h>
24 #include <asm/ist.h>
25 #include <asm/cpu_device_id.h>
26
27 #include "speedstep-lib.h"
28
29 /* speedstep system management interface port/command.
30  *
31  * These parameters are got from IST-SMI BIOS call.
32  * If user gives it, these are used.
33  *
34  */
35 static int smi_port;
36 static int smi_cmd;
37 static unsigned int smi_sig;
38
39 /* info about the processor */
40 static enum speedstep_processor speedstep_processor;
41
42 /*
43  * There are only two frequency states for each processor. Values
44  * are in kHz for the time being.
45  */
46 static struct cpufreq_frequency_table speedstep_freqs[] = {
47         {0, SPEEDSTEP_HIGH,     0},
48         {0, SPEEDSTEP_LOW,      0},
49         {0, 0,                  CPUFREQ_TABLE_END},
50 };
51
52 #define GET_SPEEDSTEP_OWNER 0
53 #define GET_SPEEDSTEP_STATE 1
54 #define SET_SPEEDSTEP_STATE 2
55 #define GET_SPEEDSTEP_FREQS 4
56
57 /* how often shall the SMI call be tried if it failed, e.g. because
58  * of DMA activity going on? */
59 #define SMI_TRIES 5
60
61 /**
62  * speedstep_smi_ownership
63  */
64 static int speedstep_smi_ownership(void)
65 {
66         u32 command, result, magic, dummy;
67         u32 function = GET_SPEEDSTEP_OWNER;
68         unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
69
70         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
71         magic = virt_to_phys(magic_data);
72
73         pr_debug("trying to obtain ownership with command %x at port %x\n",
74                         command, smi_port);
75
76         __asm__ __volatile__(
77                 "push %%ebp\n"
78                 "out %%al, (%%dx)\n"
79                 "pop %%ebp\n"
80                 : "=D" (result),
81                   "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
82                   "=S" (dummy)
83                 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
84                   "D" (0), "S" (magic)
85                 : "memory"
86         );
87
88         pr_debug("result is %x\n", result);
89
90         return result;
91 }
92
93 /**
94  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
95  * @low: the low frequency value is placed here
96  * @high: the high frequency value is placed here
97  *
98  * Only available on later SpeedStep-enabled systems, returns false results or
99  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
100  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
101  */
102 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
103 {
104         u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
105         u32 state = 0;
106         u32 function = GET_SPEEDSTEP_FREQS;
107
108         if (!(ist_info.event & 0xFFFF)) {
109                 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
110                 return -ENODEV;
111         }
112
113         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
114
115         pr_debug("trying to determine frequencies with command %x at port %x\n",
116                         command, smi_port);
117
118         __asm__ __volatile__(
119                 "push %%ebp\n"
120                 "out %%al, (%%dx)\n"
121                 "pop %%ebp"
122                 : "=a" (result),
123                   "=b" (high_mhz),
124                   "=c" (low_mhz),
125                   "=d" (state), "=D" (edi), "=S" (dummy)
126                 : "a" (command),
127                   "b" (function),
128                   "c" (state),
129                   "d" (smi_port), "S" (0), "D" (0)
130         );
131
132         pr_debug("result %x, low_freq %u, high_freq %u\n",
133                         result, low_mhz, high_mhz);
134
135         /* abort if results are obviously incorrect... */
136         if ((high_mhz + low_mhz) < 600)
137                 return -EINVAL;
138
139         *high = high_mhz * 1000;
140         *low  = low_mhz  * 1000;
141
142         return result;
143 }
144
145 /**
146  * speedstep_set_state - set the SpeedStep state
147  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
148  *
149  */
150 static void speedstep_set_state(unsigned int state)
151 {
152         unsigned int result = 0, command, new_state, dummy;
153         unsigned long flags;
154         unsigned int function = SET_SPEEDSTEP_STATE;
155         unsigned int retry = 0;
156
157         if (state > 0x1)
158                 return;
159
160         /* Disable IRQs */
161         preempt_disable();
162         local_irq_save(flags);
163
164         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
165
166         pr_debug("trying to set frequency to state %u "
167                 "with command %x at port %x\n",
168                 state, command, smi_port);
169
170         do {
171                 if (retry) {
172                         /*
173                          * We need to enable interrupts, otherwise the blockage
174                          * won't resolve.
175                          *
176                          * We disable preemption so that other processes don't
177                          * run. If other processes were running, they could
178                          * submit more DMA requests, making the blockage worse.
179                          */
180                         pr_debug("retry %u, previous result %u, waiting...\n",
181                                         retry, result);
182                         local_irq_enable();
183                         mdelay(retry * 50);
184                         local_irq_disable();
185                 }
186                 retry++;
187                 __asm__ __volatile__(
188                         "push %%ebp\n"
189                         "out %%al, (%%dx)\n"
190                         "pop %%ebp"
191                         : "=b" (new_state), "=D" (result),
192                           "=c" (dummy), "=a" (dummy),
193                           "=d" (dummy), "=S" (dummy)
194                         : "a" (command), "b" (function), "c" (state),
195                           "d" (smi_port), "S" (0), "D" (0)
196                         );
197         } while ((new_state != state) && (retry <= SMI_TRIES));
198
199         /* enable IRQs */
200         local_irq_restore(flags);
201         preempt_enable();
202
203         if (new_state == state)
204                 pr_debug("change to %u MHz succeeded after %u tries "
205                         "with result %u\n",
206                         (speedstep_freqs[new_state].frequency / 1000),
207                         retry, result);
208         else
209                 pr_err("change to state %u failed with new_state %u and result %u\n",
210                        state, new_state, result);
211
212         return;
213 }
214
215
216 /**
217  * speedstep_target - set a new CPUFreq policy
218  * @policy: new policy
219  * @index: index of new freq
220  *
221  * Sets a new CPUFreq policy/freq.
222  */
223 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
224 {
225         speedstep_set_state(index);
226
227         return 0;
228 }
229
230
231 static int speedstep_cpu_init(struct cpufreq_policy *policy)
232 {
233         int result;
234         unsigned int *low, *high;
235
236         /* capability check */
237         if (policy->cpu != 0)
238                 return -ENODEV;
239
240         result = speedstep_smi_ownership();
241         if (result) {
242                 pr_debug("fails in acquiring ownership of a SMI interface.\n");
243                 return -EINVAL;
244         }
245
246         /* detect low and high frequency */
247         low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
248         high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
249
250         result = speedstep_smi_get_freqs(low, high);
251         if (result) {
252                 /* fall back to speedstep_lib.c dection mechanism:
253                  * try both states out */
254                 pr_debug("could not detect low and high frequencies "
255                                 "by SMI call.\n");
256                 result = speedstep_get_freqs(speedstep_processor,
257                                 low, high,
258                                 NULL,
259                                 &speedstep_set_state);
260
261                 if (result) {
262                         pr_debug("could not detect two different speeds"
263                                         " -- aborting.\n");
264                         return result;
265                 } else
266                         pr_debug("workaround worked.\n");
267         }
268
269         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
270         return cpufreq_table_validate_and_show(policy, speedstep_freqs);
271 }
272
273 static unsigned int speedstep_get(unsigned int cpu)
274 {
275         if (cpu)
276                 return -ENODEV;
277         return speedstep_get_frequency(speedstep_processor);
278 }
279
280
281 static int speedstep_resume(struct cpufreq_policy *policy)
282 {
283         int result = speedstep_smi_ownership();
284
285         if (result)
286                 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
287
288         return result;
289 }
290
291 static struct cpufreq_driver speedstep_driver = {
292         .name           = "speedstep-smi",
293         .verify         = cpufreq_generic_frequency_table_verify,
294         .target_index   = speedstep_target,
295         .init           = speedstep_cpu_init,
296         .get            = speedstep_get,
297         .resume         = speedstep_resume,
298         .attr           = cpufreq_generic_attr,
299 };
300
301 static const struct x86_cpu_id ss_smi_ids[] = {
302         { X86_VENDOR_INTEL, 6, 0xb, },
303         { X86_VENDOR_INTEL, 6, 0x8, },
304         { X86_VENDOR_INTEL, 15, 2 },
305         {}
306 };
307 #if 0
308 /* Not auto loaded currently */
309 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
310 #endif
311
312 /**
313  * speedstep_init - initializes the SpeedStep CPUFreq driver
314  *
315  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
316  * BIOS, -EINVAL on problems during initiatization, and zero on
317  * success.
318  */
319 static int __init speedstep_init(void)
320 {
321         if (!x86_match_cpu(ss_smi_ids))
322                 return -ENODEV;
323
324         speedstep_processor = speedstep_detect_processor();
325
326         switch (speedstep_processor) {
327         case SPEEDSTEP_CPU_PIII_T:
328         case SPEEDSTEP_CPU_PIII_C:
329         case SPEEDSTEP_CPU_PIII_C_EARLY:
330                 break;
331         default:
332                 speedstep_processor = 0;
333         }
334
335         if (!speedstep_processor) {
336                 pr_debug("No supported Intel CPU detected.\n");
337                 return -ENODEV;
338         }
339
340         pr_debug("signature:0x%.8x, command:0x%.8x, "
341                 "event:0x%.8x, perf_level:0x%.8x.\n",
342                 ist_info.signature, ist_info.command,
343                 ist_info.event, ist_info.perf_level);
344
345         /* Error if no IST-SMI BIOS or no PARM
346                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
347         if ((ist_info.signature !=  0x47534943) && (
348             (smi_port == 0) || (smi_cmd == 0)))
349                 return -ENODEV;
350
351         if (smi_sig == 1)
352                 smi_sig = 0x47534943;
353         else
354                 smi_sig = ist_info.signature;
355
356         /* setup smi_port from MODLULE_PARM or BIOS */
357         if ((smi_port > 0xff) || (smi_port < 0))
358                 return -EINVAL;
359         else if (smi_port == 0)
360                 smi_port = ist_info.command & 0xff;
361
362         if ((smi_cmd > 0xff) || (smi_cmd < 0))
363                 return -EINVAL;
364         else if (smi_cmd == 0)
365                 smi_cmd = (ist_info.command >> 16) & 0xff;
366
367         return cpufreq_register_driver(&speedstep_driver);
368 }
369
370
371 /**
372  * speedstep_exit - unregisters SpeedStep support
373  *
374  *   Unregisters SpeedStep support.
375  */
376 static void __exit speedstep_exit(void)
377 {
378         cpufreq_unregister_driver(&speedstep_driver);
379 }
380
381 module_param(smi_port, int, 0444);
382 module_param(smi_cmd,  int, 0444);
383 module_param(smi_sig, uint, 0444);
384
385 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
386                 "-- Intel's default setting is 0xb2");
387 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
388                 "-- Intel's default setting is 0x82");
389 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
390                 "SMI interface.");
391
392 MODULE_AUTHOR("Hiroshi Miura");
393 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
394 MODULE_LICENSE("GPL");
395
396 module_init(speedstep_init);
397 module_exit(speedstep_exit);