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 #define pr_fmt(fmt) "cpufreq: " fmt
16 
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/init.h>
21 #include <linux/cpufreq.h>
22 #include <linux/delay.h>
23 #include <linux/io.h>
24 #include <asm/ist.h>
25 #include <asm/cpu_device_id.h>
26 
27 #include "speedstep-lib.h"
28 
29 /* speedstep system management interface port/command.
30  *
31  * These parameters are got from IST-SMI BIOS call.
32  * If user gives it, these are used.
33  *
34  */
35 static int smi_port;
36 static int smi_cmd;
37 static unsigned int smi_sig;
38 
39 /* info about the processor */
40 static enum speedstep_processor speedstep_processor;
41 
42 /*
43  * There are only two frequency states for each processor. Values
44  * are in kHz for the time being.
45  */
46 static struct cpufreq_frequency_table speedstep_freqs[] = {
47 	{0, SPEEDSTEP_HIGH,	0},
48 	{0, SPEEDSTEP_LOW,	0},
49 	{0, 0,			CPUFREQ_TABLE_END},
50 };
51 
52 #define GET_SPEEDSTEP_OWNER 0
53 #define GET_SPEEDSTEP_STATE 1
54 #define SET_SPEEDSTEP_STATE 2
55 #define GET_SPEEDSTEP_FREQS 4
56 
57 /* how often shall the SMI call be tried if it failed, e.g. because
58  * of DMA activity going on? */
59 #define SMI_TRIES 5
60 
61 /**
62  * speedstep_smi_ownership
63  */
64 static int speedstep_smi_ownership(void)
65 {
66 	u32 command, result, magic, dummy;
67 	u32 function = GET_SPEEDSTEP_OWNER;
68 	unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
69 
70 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
71 	magic = virt_to_phys(magic_data);
72 
73 	pr_debug("trying to obtain ownership with command %x at port %x\n",
74 			command, smi_port);
75 
76 	__asm__ __volatile__(
77 		"push %%ebp\n"
78 		"out %%al, (%%dx)\n"
79 		"pop %%ebp\n"
80 		: "=D" (result),
81 		  "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
82 		  "=S" (dummy)
83 		: "a" (command), "b" (function), "c" (0), "d" (smi_port),
84 		  "D" (0), "S" (magic)
85 		: "memory"
86 	);
87 
88 	pr_debug("result is %x\n", result);
89 
90 	return result;
91 }
92 
93 /**
94  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
95  * @low: the low frequency value is placed here
96  * @high: the high frequency value is placed here
97  *
98  * Only available on later SpeedStep-enabled systems, returns false results or
99  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
100  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
101  */
102 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
103 {
104 	u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
105 	u32 state = 0;
106 	u32 function = GET_SPEEDSTEP_FREQS;
107 
108 	if (!(ist_info.event & 0xFFFF)) {
109 		pr_debug("bug #1422 -- can't read freqs from BIOS\n");
110 		return -ENODEV;
111 	}
112 
113 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
114 
115 	pr_debug("trying to determine frequencies with command %x at port %x\n",
116 			command, smi_port);
117 
118 	__asm__ __volatile__(
119 		"push %%ebp\n"
120 		"out %%al, (%%dx)\n"
121 		"pop %%ebp"
122 		: "=a" (result),
123 		  "=b" (high_mhz),
124 		  "=c" (low_mhz),
125 		  "=d" (state), "=D" (edi), "=S" (dummy)
126 		: "a" (command),
127 		  "b" (function),
128 		  "c" (state),
129 		  "d" (smi_port), "S" (0), "D" (0)
130 	);
131 
132 	pr_debug("result %x, low_freq %u, high_freq %u\n",
133 			result, low_mhz, high_mhz);
134 
135 	/* abort if results are obviously incorrect... */
136 	if ((high_mhz + low_mhz) < 600)
137 		return -EINVAL;
138 
139 	*high = high_mhz * 1000;
140 	*low  = low_mhz  * 1000;
141 
142 	return result;
143 }
144 
145 /**
146  * speedstep_set_state - set the SpeedStep state
147  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
148  *
149  */
150 static void speedstep_set_state(unsigned int state)
151 {
152 	unsigned int result = 0, command, new_state, dummy;
153 	unsigned long flags;
154 	unsigned int function = SET_SPEEDSTEP_STATE;
155 	unsigned int retry = 0;
156 
157 	if (state > 0x1)
158 		return;
159 
160 	/* Disable IRQs */
161 	preempt_disable();
162 	local_irq_save(flags);
163 
164 	command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
165 
166 	pr_debug("trying to set frequency to state %u "
167 		"with command %x at port %x\n",
168 		state, command, smi_port);
169 
170 	do {
171 		if (retry) {
172 			/*
173 			 * We need to enable interrupts, otherwise the blockage
174 			 * won't resolve.
175 			 *
176 			 * We disable preemption so that other processes don't
177 			 * run. If other processes were running, they could
178 			 * submit more DMA requests, making the blockage worse.
179 			 */
180 			pr_debug("retry %u, previous result %u, waiting...\n",
181 					retry, result);
182 			local_irq_enable();
183 			mdelay(retry * 50);
184 			local_irq_disable();
185 		}
186 		retry++;
187 		__asm__ __volatile__(
188 			"push %%ebp\n"
189 			"out %%al, (%%dx)\n"
190 			"pop %%ebp"
191 			: "=b" (new_state), "=D" (result),
192 			  "=c" (dummy), "=a" (dummy),
193 			  "=d" (dummy), "=S" (dummy)
194 			: "a" (command), "b" (function), "c" (state),
195 			  "d" (smi_port), "S" (0), "D" (0)
196 			);
197 	} while ((new_state != state) && (retry <= SMI_TRIES));
198 
199 	/* enable IRQs */
200 	local_irq_restore(flags);
201 	preempt_enable();
202 
203 	if (new_state == state)
204 		pr_debug("change to %u MHz succeeded after %u tries "
205 			"with result %u\n",
206 			(speedstep_freqs[new_state].frequency / 1000),
207 			retry, result);
208 	else
209 		pr_err("change to state %u failed with new_state %u and result %u\n",
210 		       state, new_state, result);
211 
212 	return;
213 }
214 
215 
216 /**
217  * speedstep_target - set a new CPUFreq policy
218  * @policy: new policy
219  * @index: index of new freq
220  *
221  * Sets a new CPUFreq policy/freq.
222  */
223 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
224 {
225 	speedstep_set_state(index);
226 
227 	return 0;
228 }
229 
230 
231 static int speedstep_cpu_init(struct cpufreq_policy *policy)
232 {
233 	int result;
234 	unsigned int *low, *high;
235 
236 	/* capability check */
237 	if (policy->cpu != 0)
238 		return -ENODEV;
239 
240 	result = speedstep_smi_ownership();
241 	if (result) {
242 		pr_debug("fails in acquiring ownership of a SMI interface.\n");
243 		return -EINVAL;
244 	}
245 
246 	/* detect low and high frequency */
247 	low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
248 	high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
249 
250 	result = speedstep_smi_get_freqs(low, high);
251 	if (result) {
252 		/* fall back to speedstep_lib.c dection mechanism:
253 		 * try both states out */
254 		pr_debug("could not detect low and high frequencies "
255 				"by SMI call.\n");
256 		result = speedstep_get_freqs(speedstep_processor,
257 				low, high,
258 				NULL,
259 				&speedstep_set_state);
260 
261 		if (result) {
262 			pr_debug("could not detect two different speeds"
263 					" -- aborting.\n");
264 			return result;
265 		} else
266 			pr_debug("workaround worked.\n");
267 	}
268 
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 	.flags		= CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
293 	.verify		= cpufreq_generic_frequency_table_verify,
294 	.target_index	= speedstep_target,
295 	.init		= speedstep_cpu_init,
296 	.get		= speedstep_get,
297 	.resume		= speedstep_resume,
298 	.attr		= cpufreq_generic_attr,
299 };
300 
301 static const struct x86_cpu_id ss_smi_ids[] = {
302 	{ X86_VENDOR_INTEL, 6, 0xb, },
303 	{ X86_VENDOR_INTEL, 6, 0x8, },
304 	{ X86_VENDOR_INTEL, 15, 2 },
305 	{}
306 };
307 #if 0
308 /* Not auto loaded currently */
309 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
310 #endif
311 
312 /**
313  * speedstep_init - initializes the SpeedStep CPUFreq driver
314  *
315  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
316  * BIOS, -EINVAL on problems during initiatization, and zero on
317  * success.
318  */
319 static int __init speedstep_init(void)
320 {
321 	if (!x86_match_cpu(ss_smi_ids))
322 		return -ENODEV;
323 
324 	speedstep_processor = speedstep_detect_processor();
325 
326 	switch (speedstep_processor) {
327 	case SPEEDSTEP_CPU_PIII_T:
328 	case SPEEDSTEP_CPU_PIII_C:
329 	case SPEEDSTEP_CPU_PIII_C_EARLY:
330 		break;
331 	default:
332 		speedstep_processor = 0;
333 	}
334 
335 	if (!speedstep_processor) {
336 		pr_debug("No supported Intel CPU detected.\n");
337 		return -ENODEV;
338 	}
339 
340 	pr_debug("signature:0x%.8x, command:0x%.8x, "
341 		"event:0x%.8x, perf_level:0x%.8x.\n",
342 		ist_info.signature, ist_info.command,
343 		ist_info.event, ist_info.perf_level);
344 
345 	/* Error if no IST-SMI BIOS or no PARM
346 		 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
347 	if ((ist_info.signature !=  0x47534943) && (
348 	    (smi_port == 0) || (smi_cmd == 0)))
349 		return -ENODEV;
350 
351 	if (smi_sig == 1)
352 		smi_sig = 0x47534943;
353 	else
354 		smi_sig = ist_info.signature;
355 
356 	/* setup smi_port from MODLULE_PARM or BIOS */
357 	if ((smi_port > 0xff) || (smi_port < 0))
358 		return -EINVAL;
359 	else if (smi_port == 0)
360 		smi_port = ist_info.command & 0xff;
361 
362 	if ((smi_cmd > 0xff) || (smi_cmd < 0))
363 		return -EINVAL;
364 	else if (smi_cmd == 0)
365 		smi_cmd = (ist_info.command >> 16) & 0xff;
366 
367 	return cpufreq_register_driver(&speedstep_driver);
368 }
369 
370 
371 /**
372  * speedstep_exit - unregisters SpeedStep support
373  *
374  *   Unregisters SpeedStep support.
375  */
376 static void __exit speedstep_exit(void)
377 {
378 	cpufreq_unregister_driver(&speedstep_driver);
379 }
380 
381 module_param_hw(smi_port, int, ioport, 0444);
382 module_param(smi_cmd,  int, 0444);
383 module_param(smi_sig, uint, 0444);
384 
385 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
386 		"-- Intel's default setting is 0xb2");
387 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
388 		"-- Intel's default setting is 0x82");
389 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
390 		"SMI interface.");
391 
392 MODULE_AUTHOR("Hiroshi Miura");
393 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
394 MODULE_LICENSE("GPL");
395 
396 module_init(speedstep_init);
397 module_exit(speedstep_exit);
398