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);
397