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 	{SPEEDSTEP_HIGH,	0},
46 	{SPEEDSTEP_LOW,		0},
47 	{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 	local_irq_save(flags);
160 
161 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
162 
163 	pr_debug("trying to set frequency to state %u "
164 		"with command %x at port %x\n",
165 		state, command, smi_port);
166 
167 	do {
168 		if (retry) {
169 			pr_debug("retry %u, previous result %u, waiting...\n",
170 					retry, result);
171 			mdelay(retry * 50);
172 		}
173 		retry++;
174 		__asm__ __volatile__(
175 			"push %%ebp\n"
176 			"out %%al, (%%dx)\n"
177 			"pop %%ebp"
178 			: "=b" (new_state), "=D" (result),
179 			  "=c" (dummy), "=a" (dummy),
180 			  "=d" (dummy), "=S" (dummy)
181 			: "a" (command), "b" (function), "c" (state),
182 			  "d" (smi_port), "S" (0), "D" (0)
183 			);
184 	} while ((new_state != state) && (retry <= SMI_TRIES));
185 
186 	/* enable IRQs */
187 	local_irq_restore(flags);
188 
189 	if (new_state == state)
190 		pr_debug("change to %u MHz succeeded after %u tries "
191 			"with result %u\n",
192 			(speedstep_freqs[new_state].frequency / 1000),
193 			retry, result);
194 	else
195 		printk(KERN_ERR "cpufreq: change to state %u "
196 			"failed with new_state %u and result %u\n",
197 			state, new_state, result);
198 
199 	return;
200 }
201 
202 
203 /**
204  * speedstep_target - set a new CPUFreq policy
205  * @policy: new policy
206  * @index: index of new freq
207  *
208  * Sets a new CPUFreq policy/freq.
209  */
210 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
211 {
212 	speedstep_set_state(index);
213 
214 	return 0;
215 }
216 
217 
218 static int speedstep_cpu_init(struct cpufreq_policy *policy)
219 {
220 	int result;
221 	unsigned int *low, *high;
222 
223 	/* capability check */
224 	if (policy->cpu != 0)
225 		return -ENODEV;
226 
227 	result = speedstep_smi_ownership();
228 	if (result) {
229 		pr_debug("fails in acquiring ownership of a SMI interface.\n");
230 		return -EINVAL;
231 	}
232 
233 	/* detect low and high frequency */
234 	low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
235 	high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
236 
237 	result = speedstep_smi_get_freqs(low, high);
238 	if (result) {
239 		/* fall back to speedstep_lib.c dection mechanism:
240 		 * try both states out */
241 		pr_debug("could not detect low and high frequencies "
242 				"by SMI call.\n");
243 		result = speedstep_get_freqs(speedstep_processor,
244 				low, high,
245 				NULL,
246 				&speedstep_set_state);
247 
248 		if (result) {
249 			pr_debug("could not detect two different speeds"
250 					" -- aborting.\n");
251 			return result;
252 		} else
253 			pr_debug("workaround worked.\n");
254 	}
255 
256 	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
257 	return cpufreq_table_validate_and_show(policy, speedstep_freqs);
258 }
259 
260 static unsigned int speedstep_get(unsigned int cpu)
261 {
262 	if (cpu)
263 		return -ENODEV;
264 	return speedstep_get_frequency(speedstep_processor);
265 }
266 
267 
268 static int speedstep_resume(struct cpufreq_policy *policy)
269 {
270 	int result = speedstep_smi_ownership();
271 
272 	if (result)
273 		pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
274 
275 	return result;
276 }
277 
278 static struct cpufreq_driver speedstep_driver = {
279 	.name		= "speedstep-smi",
280 	.verify		= cpufreq_generic_frequency_table_verify,
281 	.target_index	= speedstep_target,
282 	.init		= speedstep_cpu_init,
283 	.exit		= cpufreq_generic_exit,
284 	.get		= speedstep_get,
285 	.resume		= speedstep_resume,
286 	.attr		= cpufreq_generic_attr,
287 };
288 
289 static const struct x86_cpu_id ss_smi_ids[] = {
290 	{ X86_VENDOR_INTEL, 6, 0xb, },
291 	{ X86_VENDOR_INTEL, 6, 0x8, },
292 	{ X86_VENDOR_INTEL, 15, 2 },
293 	{}
294 };
295 #if 0
296 /* Not auto loaded currently */
297 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
298 #endif
299 
300 /**
301  * speedstep_init - initializes the SpeedStep CPUFreq driver
302  *
303  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
304  * BIOS, -EINVAL on problems during initiatization, and zero on
305  * success.
306  */
307 static int __init speedstep_init(void)
308 {
309 	if (!x86_match_cpu(ss_smi_ids))
310 		return -ENODEV;
311 
312 	speedstep_processor = speedstep_detect_processor();
313 
314 	switch (speedstep_processor) {
315 	case SPEEDSTEP_CPU_PIII_T:
316 	case SPEEDSTEP_CPU_PIII_C:
317 	case SPEEDSTEP_CPU_PIII_C_EARLY:
318 		break;
319 	default:
320 		speedstep_processor = 0;
321 	}
322 
323 	if (!speedstep_processor) {
324 		pr_debug("No supported Intel CPU detected.\n");
325 		return -ENODEV;
326 	}
327 
328 	pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
329 		"event:0x%.8ulx, perf_level:0x%.8ulx.\n",
330 		ist_info.signature, ist_info.command,
331 		ist_info.event, ist_info.perf_level);
332 
333 	/* Error if no IST-SMI BIOS or no PARM
334 		 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
335 	if ((ist_info.signature !=  0x47534943) && (
336 	    (smi_port == 0) || (smi_cmd == 0)))
337 		return -ENODEV;
338 
339 	if (smi_sig == 1)
340 		smi_sig = 0x47534943;
341 	else
342 		smi_sig = ist_info.signature;
343 
344 	/* setup smi_port from MODLULE_PARM or BIOS */
345 	if ((smi_port > 0xff) || (smi_port < 0))
346 		return -EINVAL;
347 	else if (smi_port == 0)
348 		smi_port = ist_info.command & 0xff;
349 
350 	if ((smi_cmd > 0xff) || (smi_cmd < 0))
351 		return -EINVAL;
352 	else if (smi_cmd == 0)
353 		smi_cmd = (ist_info.command >> 16) & 0xff;
354 
355 	return cpufreq_register_driver(&speedstep_driver);
356 }
357 
358 
359 /**
360  * speedstep_exit - unregisters SpeedStep support
361  *
362  *   Unregisters SpeedStep support.
363  */
364 static void __exit speedstep_exit(void)
365 {
366 	cpufreq_unregister_driver(&speedstep_driver);
367 }
368 
369 module_param(smi_port, int, 0444);
370 module_param(smi_cmd,  int, 0444);
371 module_param(smi_sig, uint, 0444);
372 
373 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
374 		"-- Intel's default setting is 0xb2");
375 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
376 		"-- Intel's default setting is 0x82");
377 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
378 		"SMI interface.");
379 
380 MODULE_AUTHOR("Hiroshi Miura");
381 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
382 MODULE_LICENSE("GPL");
383 
384 module_init(speedstep_init);
385 module_exit(speedstep_exit);
386