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/slab.h>
21 #include <linux/delay.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.
33 static int smi_port = 0;
34 static int smi_cmd = 0;
35 static unsigned int smi_sig = 0;
37 /* info about the processor */
38 static unsigned int speedstep_processor = 0;
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? */
59 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "speedstep-smi", msg)
62 * speedstep_smi_ownership
64 static int speedstep_smi_ownership (void)
66 u32 command, result, magic;
67 u32 function = GET_SPEEDSTEP_OWNER;
68 unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
70 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
71 magic = virt_to_phys(magic_data);
73 dprintk("trying to obtain ownership with command %x at port %x\n", command, smi_port);
78 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
83 dprintk("result is %x\n", result);
89 * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
90 * @low: the low frequency value is placed here
91 * @high: the high frequency value is placed here
93 * Only available on later SpeedStep-enabled systems, returns false results or
94 * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
95 * shows that the latter occurs if !(ist_info.event & 0xFFFF).
97 static int speedstep_smi_get_freqs (unsigned int *low, unsigned int *high)
99 u32 command, result = 0, edi, high_mhz, low_mhz;
101 u32 function = GET_SPEEDSTEP_FREQS;
103 if (!(ist_info.event & 0xFFFF)) {
104 dprintk("bug #1422 -- can't read freqs from BIOS\n");
108 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
110 dprintk("trying to determine frequencies with command %x at port %x\n", command, smi_port);
112 __asm__ __volatile__("movl $0, %%edi\n"
114 : "=a" (result), "=b" (high_mhz), "=c" (low_mhz), "=d" (state), "=D" (edi)
115 : "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
118 dprintk("result %x, low_freq %u, high_freq %u\n", result, low_mhz, high_mhz);
120 /* abort if results are obviously incorrect... */
121 if ((high_mhz + low_mhz) < 600)
124 *high = high_mhz * 1000;
125 *low = low_mhz * 1000;
131 * speedstep_get_state - set the SpeedStep state
132 * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
135 static int speedstep_get_state (void)
137 u32 function=GET_SPEEDSTEP_STATE;
138 u32 result, state, edi, command;
140 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
142 dprintk("trying to determine current setting with command %x at port %x\n", command, smi_port);
144 __asm__ __volatile__("movl $0, %%edi\n"
146 : "=a" (result), "=b" (state), "=D" (edi)
147 : "a" (command), "b" (function), "c" (0), "d" (smi_port), "S" (0)
150 dprintk("state is %x, result is %x\n", state, result);
157 * speedstep_set_state - set the SpeedStep state
158 * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
161 static void speedstep_set_state (unsigned int state)
163 unsigned int result = 0, command, new_state;
165 unsigned int function=SET_SPEEDSTEP_STATE;
166 unsigned int retry = 0;
172 local_irq_save(flags);
174 command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
176 dprintk("trying to set frequency to state %u with command %x at port %x\n", state, command, smi_port);
180 dprintk("retry %u, previous result %u, waiting...\n", retry, result);
184 __asm__ __volatile__(
187 : "=b" (new_state), "=D" (result)
188 : "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
190 } while ((new_state != state) && (retry <= SMI_TRIES));
193 local_irq_restore(flags);
195 if (new_state == state) {
196 dprintk("change to %u MHz succeeded after %u tries with result %u\n", (speedstep_freqs[new_state].frequency / 1000), retry, result);
198 printk(KERN_ERR "cpufreq: change failed with new_state %u and result %u\n", new_state, result);
206 * speedstep_target - set a new CPUFreq policy
207 * @policy: new policy
208 * @target_freq: new freq
211 * Sets a new CPUFreq policy/freq.
213 static int speedstep_target (struct cpufreq_policy *policy,
214 unsigned int target_freq, unsigned int relation)
216 unsigned int newstate = 0;
217 struct cpufreq_freqs freqs;
219 if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0], target_freq, relation, &newstate))
222 freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
223 freqs.new = speedstep_freqs[newstate].frequency;
224 freqs.cpu = 0; /* speedstep.c is UP only driver */
226 if (freqs.old == freqs.new)
229 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
230 speedstep_set_state(newstate);
231 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
238 * speedstep_verify - verifies a new CPUFreq policy
239 * @policy: new policy
241 * Limit must be within speedstep_low_freq and speedstep_high_freq, with
242 * at least one border included.
244 static int speedstep_verify (struct cpufreq_policy *policy)
246 return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
250 static int speedstep_cpu_init(struct cpufreq_policy *policy)
253 unsigned int speed,state;
255 /* capability check */
256 if (policy->cpu != 0)
259 result = speedstep_smi_ownership();
261 dprintk("fails in aquiring ownership of a SMI interface.\n");
265 /* detect low and high frequency */
266 result = speedstep_smi_get_freqs(&speedstep_freqs[SPEEDSTEP_LOW].frequency,
267 &speedstep_freqs[SPEEDSTEP_HIGH].frequency);
269 /* fall back to speedstep_lib.c dection mechanism: try both states out */
270 dprintk("could not detect low and high frequencies by SMI call.\n");
271 result = speedstep_get_freqs(speedstep_processor,
272 &speedstep_freqs[SPEEDSTEP_LOW].frequency,
273 &speedstep_freqs[SPEEDSTEP_HIGH].frequency,
275 &speedstep_set_state);
278 dprintk("could not detect two different speeds -- aborting.\n");
281 dprintk("workaround worked.\n");
284 /* get current speed setting */
285 state = speedstep_get_state();
286 speed = speedstep_freqs[state].frequency;
288 dprintk("currently at %s speed setting - %i MHz\n",
289 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency) ? "low" : "high",
292 /* cpuinfo and default policy values */
293 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
296 result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
300 cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
305 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
307 cpufreq_frequency_table_put_attr(policy->cpu);
311 static unsigned int speedstep_get(unsigned int cpu)
315 return speedstep_get_processor_frequency(speedstep_processor);
319 static int speedstep_resume(struct cpufreq_policy *policy)
321 int result = speedstep_smi_ownership();
324 dprintk("fails in re-aquiring ownership of a SMI interface.\n");
329 static struct freq_attr* speedstep_attr[] = {
330 &cpufreq_freq_attr_scaling_available_freqs,
334 static struct cpufreq_driver speedstep_driver = {
335 .name = "speedstep-smi",
336 .verify = speedstep_verify,
337 .target = speedstep_target,
338 .init = speedstep_cpu_init,
339 .exit = speedstep_cpu_exit,
340 .get = speedstep_get,
341 .resume = speedstep_resume,
342 .owner = THIS_MODULE,
343 .attr = speedstep_attr,
347 * speedstep_init - initializes the SpeedStep CPUFreq driver
349 * Initializes the SpeedStep support. Returns -ENODEV on unsupported
350 * BIOS, -EINVAL on problems during initiatization, and zero on
353 static int __init speedstep_init(void)
355 speedstep_processor = speedstep_detect_processor();
357 switch (speedstep_processor) {
358 case SPEEDSTEP_PROCESSOR_PIII_T:
359 case SPEEDSTEP_PROCESSOR_PIII_C:
360 case SPEEDSTEP_PROCESSOR_PIII_C_EARLY:
363 speedstep_processor = 0;
366 if (!speedstep_processor) {
367 dprintk ("No supported Intel CPU detected.\n");
371 dprintk("signature:0x%.8lx, command:0x%.8lx, event:0x%.8lx, perf_level:0x%.8lx.\n",
372 ist_info.signature, ist_info.command, ist_info.event, ist_info.perf_level);
374 /* Error if no IST-SMI BIOS or no PARM
375 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
376 if ((ist_info.signature != 0x47534943) && (
377 (smi_port == 0) || (smi_cmd == 0)))
381 smi_sig = 0x47534943;
383 smi_sig = ist_info.signature;
385 /* setup smi_port from MODLULE_PARM or BIOS */
386 if ((smi_port > 0xff) || (smi_port < 0))
388 else if (smi_port == 0)
389 smi_port = ist_info.command & 0xff;
391 if ((smi_cmd > 0xff) || (smi_cmd < 0))
393 else if (smi_cmd == 0)
394 smi_cmd = (ist_info.command >> 16) & 0xff;
396 return cpufreq_register_driver(&speedstep_driver);
401 * speedstep_exit - unregisters SpeedStep support
403 * Unregisters SpeedStep support.
405 static void __exit speedstep_exit(void)
407 cpufreq_unregister_driver(&speedstep_driver);
410 module_param(smi_port, int, 0444);
411 module_param(smi_cmd, int, 0444);
412 module_param(smi_sig, uint, 0444);
414 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value -- Intel's default setting is 0xb2");
415 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value -- Intel's default setting is 0x82");
416 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the SMI interface.");
418 MODULE_AUTHOR ("Hiroshi Miura");
419 MODULE_DESCRIPTION ("Speedstep driver for IST applet SMI interface.");
420 MODULE_LICENSE ("GPL");
422 module_init(speedstep_init);
423 module_exit(speedstep_exit);