2 * Intel SpeedStep SMI driver.
4 * (C) 2003 Hiroshi Miura <miura@da-cha.org>
6 * Licensed under the terms of the GNU GPL License version 2.
11 /*********************************************************************
12 * SPEEDSTEP - DEFINITIONS *
13 *********************************************************************/
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>
23 #include <asm/cpu_device_id.h>
25 #include "speedstep-lib.h"
27 /* speedstep system management interface port/command.
29 * These parameters are got from IST-SMI BIOS call.
30 * If user gives it, these are used.
35 static unsigned int smi_sig
;
37 /* info about the processor */
38 static enum speedstep_processor speedstep_processor
;
41 * There are only two frequency states for each processor. Values
42 * are in kHz for the time being.
44 static struct cpufreq_frequency_table speedstep_freqs
[] = {
47 {0, CPUFREQ_TABLE_END
},
50 #define GET_SPEEDSTEP_OWNER 0
51 #define GET_SPEEDSTEP_STATE 1
52 #define SET_SPEEDSTEP_STATE 2
53 #define GET_SPEEDSTEP_FREQS 4
55 /* how often shall the SMI call be tried if it failed, e.g. because
56 * of DMA activity going on? */
60 * speedstep_smi_ownership
62 static int speedstep_smi_ownership(void)
64 u32 command
, result
, magic
, dummy
;
65 u32 function
= GET_SPEEDSTEP_OWNER
;
66 unsigned char magic_data
[] = "Copyright (c) 1999 Intel Corporation";
68 command
= (smi_sig
& 0xffffff00) | (smi_cmd
& 0xff);
69 magic
= virt_to_phys(magic_data
);
71 pr_debug("trying to obtain ownership with command %x at port %x\n",
79 "=a" (dummy
), "=b" (dummy
), "=c" (dummy
), "=d" (dummy
),
81 : "a" (command
), "b" (function
), "c" (0), "d" (smi_port
),
86 pr_debug("result is %x\n", result
);
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
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).
100 static int speedstep_smi_get_freqs(unsigned int *low
, unsigned int *high
)
102 u32 command
, result
= 0, edi
, high_mhz
, low_mhz
, dummy
;
104 u32 function
= GET_SPEEDSTEP_FREQS
;
106 if (!(ist_info
.event
& 0xFFFF)) {
107 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
111 command
= (smi_sig
& 0xffffff00) | (smi_cmd
& 0xff);
113 pr_debug("trying to determine frequencies with command %x at port %x\n",
116 __asm__
__volatile__(
123 "=d" (state
), "=D" (edi
), "=S" (dummy
)
127 "d" (smi_port
), "S" (0), "D" (0)
130 pr_debug("result %x, low_freq %u, high_freq %u\n",
131 result
, low_mhz
, high_mhz
);
133 /* abort if results are obviously incorrect... */
134 if ((high_mhz
+ low_mhz
) < 600)
137 *high
= high_mhz
* 1000;
138 *low
= low_mhz
* 1000;
144 * speedstep_get_state - set the SpeedStep state
145 * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
148 static int speedstep_get_state(void)
150 u32 function
= GET_SPEEDSTEP_STATE
;
151 u32 result
, state
, edi
, command
, dummy
;
153 command
= (smi_sig
& 0xffffff00) | (smi_cmd
& 0xff);
155 pr_debug("trying to determine current setting with command %x "
156 "at port %x\n", command
, smi_port
);
158 __asm__
__volatile__(
163 "=b" (state
), "=D" (edi
),
164 "=c" (dummy
), "=d" (dummy
), "=S" (dummy
)
165 : "a" (command
), "b" (function
), "c" (0),
166 "d" (smi_port
), "S" (0), "D" (0)
169 pr_debug("state is %x, result is %x\n", state
, result
);
176 * speedstep_set_state - set the SpeedStep state
177 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
180 static void speedstep_set_state(unsigned int state
)
182 unsigned int result
= 0, command
, new_state
, dummy
;
184 unsigned int function
= SET_SPEEDSTEP_STATE
;
185 unsigned int retry
= 0;
191 local_irq_save(flags
);
193 command
= (smi_sig
& 0xffffff00) | (smi_cmd
& 0xff);
195 pr_debug("trying to set frequency to state %u "
196 "with command %x at port %x\n",
197 state
, command
, smi_port
);
201 pr_debug("retry %u, previous result %u, waiting...\n",
206 __asm__
__volatile__(
210 : "=b" (new_state
), "=D" (result
),
211 "=c" (dummy
), "=a" (dummy
),
212 "=d" (dummy
), "=S" (dummy
)
213 : "a" (command
), "b" (function
), "c" (state
),
214 "d" (smi_port
), "S" (0), "D" (0)
216 } while ((new_state
!= state
) && (retry
<= SMI_TRIES
));
219 local_irq_restore(flags
);
221 if (new_state
== state
)
222 pr_debug("change to %u MHz succeeded after %u tries "
224 (speedstep_freqs
[new_state
].frequency
/ 1000),
227 printk(KERN_ERR
"cpufreq: change to state %u "
228 "failed with new_state %u and result %u\n",
229 state
, new_state
, result
);
236 * speedstep_target - set a new CPUFreq policy
237 * @policy: new policy
238 * @index: index of new freq
240 * Sets a new CPUFreq policy/freq.
242 static int speedstep_target(struct cpufreq_policy
*policy
, unsigned int index
)
244 speedstep_set_state(index
);
250 static int speedstep_cpu_init(struct cpufreq_policy
*policy
)
253 unsigned int *low
, *high
;
255 /* capability check */
256 if (policy
->cpu
!= 0)
259 result
= speedstep_smi_ownership();
261 pr_debug("fails in acquiring ownership of a SMI interface.\n");
265 /* detect low and high frequency */
266 low
= &speedstep_freqs
[SPEEDSTEP_LOW
].frequency
;
267 high
= &speedstep_freqs
[SPEEDSTEP_HIGH
].frequency
;
269 result
= speedstep_smi_get_freqs(low
, high
);
271 /* fall back to speedstep_lib.c dection mechanism:
272 * try both states out */
273 pr_debug("could not detect low and high frequencies "
275 result
= speedstep_get_freqs(speedstep_processor
,
278 &speedstep_set_state
);
281 pr_debug("could not detect two different speeds"
285 pr_debug("workaround worked.\n");
288 policy
->cpuinfo
.transition_latency
= CPUFREQ_ETERNAL
;
289 return cpufreq_table_validate_and_show(policy
, speedstep_freqs
);
292 static unsigned int speedstep_get(unsigned int cpu
)
296 return speedstep_get_frequency(speedstep_processor
);
300 static int speedstep_resume(struct cpufreq_policy
*policy
)
302 int result
= speedstep_smi_ownership();
305 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
310 static struct cpufreq_driver speedstep_driver
= {
311 .name
= "speedstep-smi",
312 .verify
= cpufreq_generic_frequency_table_verify
,
313 .target_index
= speedstep_target
,
314 .init
= speedstep_cpu_init
,
315 .exit
= cpufreq_generic_exit
,
316 .get
= speedstep_get
,
317 .resume
= speedstep_resume
,
318 .attr
= cpufreq_generic_attr
,
321 static const struct x86_cpu_id ss_smi_ids
[] = {
322 { X86_VENDOR_INTEL
, 6, 0xb, },
323 { X86_VENDOR_INTEL
, 6, 0x8, },
324 { X86_VENDOR_INTEL
, 15, 2 },
328 /* Not auto loaded currently */
329 MODULE_DEVICE_TABLE(x86cpu
, ss_smi_ids
);
333 * speedstep_init - initializes the SpeedStep CPUFreq driver
335 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
336 * BIOS, -EINVAL on problems during initiatization, and zero on
339 static int __init
speedstep_init(void)
341 if (!x86_match_cpu(ss_smi_ids
))
344 speedstep_processor
= speedstep_detect_processor();
346 switch (speedstep_processor
) {
347 case SPEEDSTEP_CPU_PIII_T
:
348 case SPEEDSTEP_CPU_PIII_C
:
349 case SPEEDSTEP_CPU_PIII_C_EARLY
:
352 speedstep_processor
= 0;
355 if (!speedstep_processor
) {
356 pr_debug("No supported Intel CPU detected.\n");
360 pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
361 "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
362 ist_info
.signature
, ist_info
.command
,
363 ist_info
.event
, ist_info
.perf_level
);
365 /* Error if no IST-SMI BIOS or no PARM
366 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
367 if ((ist_info
.signature
!= 0x47534943) && (
368 (smi_port
== 0) || (smi_cmd
== 0)))
372 smi_sig
= 0x47534943;
374 smi_sig
= ist_info
.signature
;
376 /* setup smi_port from MODLULE_PARM or BIOS */
377 if ((smi_port
> 0xff) || (smi_port
< 0))
379 else if (smi_port
== 0)
380 smi_port
= ist_info
.command
& 0xff;
382 if ((smi_cmd
> 0xff) || (smi_cmd
< 0))
384 else if (smi_cmd
== 0)
385 smi_cmd
= (ist_info
.command
>> 16) & 0xff;
387 return cpufreq_register_driver(&speedstep_driver
);
392 * speedstep_exit - unregisters SpeedStep support
394 * Unregisters SpeedStep support.
396 static void __exit
speedstep_exit(void)
398 cpufreq_unregister_driver(&speedstep_driver
);
401 module_param(smi_port
, int, 0444);
402 module_param(smi_cmd
, int, 0444);
403 module_param(smi_sig
, uint
, 0444);
405 MODULE_PARM_DESC(smi_port
, "Override the BIOS-given IST port with this value "
406 "-- Intel's default setting is 0xb2");
407 MODULE_PARM_DESC(smi_cmd
, "Override the BIOS-given IST command with this value "
408 "-- Intel's default setting is 0x82");
409 MODULE_PARM_DESC(smi_sig
, "Set to 1 to fake the IST signature when using the "
412 MODULE_AUTHOR("Hiroshi Miura");
413 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
414 MODULE_LICENSE("GPL");
416 module_init(speedstep_init
);
417 module_exit(speedstep_exit
);