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