1 /*
2  * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
3  *
4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
6  *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
7  *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
8  *  			- Added processor hotplug support
9  *
10  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
11  *
12  *  This program is free software; you can redistribute it and/or modify
13  *  it under the terms of the GNU General Public License as published by
14  *  the Free Software Foundation; either version 2 of the License, or (at
15  *  your option) any later version.
16  *
17  *  This program is distributed in the hope that it will be useful, but
18  *  WITHOUT ANY WARRANTY; without even the implied warranty of
19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20  *  General Public License for more details.
21  *
22  *  You should have received a copy of the GNU General Public License along
23  *  with this program; if not, write to the Free Software Foundation, Inc.,
24  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
25  *
26  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
27  */
28 
29 #include <linux/kernel.h>
30 #include <linux/module.h>
31 #include <linux/init.h>
32 #include <linux/cpufreq.h>
33 #include <linux/proc_fs.h>
34 #include <linux/seq_file.h>
35 
36 #include <asm/uaccess.h>
37 
38 #include <acpi/acpi_bus.h>
39 #include <acpi/processor.h>
40 #include <acpi/acpi_drivers.h>
41 
42 #define ACPI_PROCESSOR_COMPONENT        0x01000000
43 #define ACPI_PROCESSOR_CLASS            "processor"
44 #define ACPI_PROCESSOR_DRIVER_NAME      "ACPI Processor Driver"
45 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
46 ACPI_MODULE_NAME("acpi_processor")
47 
48 /* --------------------------------------------------------------------------
49                                  Limit Interface
50    -------------------------------------------------------------------------- */
51 static int acpi_processor_apply_limit(struct acpi_processor *pr)
52 {
53 	int result = 0;
54 	u16 px = 0;
55 	u16 tx = 0;
56 
57 	ACPI_FUNCTION_TRACE("acpi_processor_apply_limit");
58 
59 	if (!pr)
60 		return_VALUE(-EINVAL);
61 
62 	if (!pr->flags.limit)
63 		return_VALUE(-ENODEV);
64 
65 	if (pr->flags.throttling) {
66 		if (pr->limit.user.tx > tx)
67 			tx = pr->limit.user.tx;
68 		if (pr->limit.thermal.tx > tx)
69 			tx = pr->limit.thermal.tx;
70 
71 		result = acpi_processor_set_throttling(pr, tx);
72 		if (result)
73 			goto end;
74 	}
75 
76 	pr->limit.state.px = px;
77 	pr->limit.state.tx = tx;
78 
79 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
80 			  "Processor [%d] limit set to (P%d:T%d)\n", pr->id,
81 			  pr->limit.state.px, pr->limit.state.tx));
82 
83       end:
84 	if (result)
85 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Unable to set limit\n"));
86 
87 	return_VALUE(result);
88 }
89 
90 #ifdef CONFIG_CPU_FREQ
91 
92 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
93  * offers (in most cases) voltage scaling in addition to frequency scaling, and
94  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
95  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
96  */
97 
98 static unsigned int cpufreq_thermal_reduction_pctg[NR_CPUS];
99 static unsigned int acpi_thermal_cpufreq_is_init = 0;
100 
101 static int cpu_has_cpufreq(unsigned int cpu)
102 {
103 	struct cpufreq_policy policy;
104 	if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
105 		return 0;
106 	return 1;
107 }
108 
109 static int acpi_thermal_cpufreq_increase(unsigned int cpu)
110 {
111 	if (!cpu_has_cpufreq(cpu))
112 		return -ENODEV;
113 
114 	if (cpufreq_thermal_reduction_pctg[cpu] < 60) {
115 		cpufreq_thermal_reduction_pctg[cpu] += 20;
116 		cpufreq_update_policy(cpu);
117 		return 0;
118 	}
119 
120 	return -ERANGE;
121 }
122 
123 static int acpi_thermal_cpufreq_decrease(unsigned int cpu)
124 {
125 	if (!cpu_has_cpufreq(cpu))
126 		return -ENODEV;
127 
128 	if (cpufreq_thermal_reduction_pctg[cpu] > 20)
129 		cpufreq_thermal_reduction_pctg[cpu] -= 20;
130 	else
131 		cpufreq_thermal_reduction_pctg[cpu] = 0;
132 	cpufreq_update_policy(cpu);
133 	/* We reached max freq again and can leave passive mode */
134 	return !cpufreq_thermal_reduction_pctg[cpu];
135 }
136 
137 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
138 					 unsigned long event, void *data)
139 {
140 	struct cpufreq_policy *policy = data;
141 	unsigned long max_freq = 0;
142 
143 	if (event != CPUFREQ_ADJUST)
144 		goto out;
145 
146 	max_freq =
147 	    (policy->cpuinfo.max_freq *
148 	     (100 - cpufreq_thermal_reduction_pctg[policy->cpu])) / 100;
149 
150 	cpufreq_verify_within_limits(policy, 0, max_freq);
151 
152       out:
153 	return 0;
154 }
155 
156 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
157 	.notifier_call = acpi_thermal_cpufreq_notifier,
158 };
159 
160 void acpi_thermal_cpufreq_init(void)
161 {
162 	int i;
163 
164 	for (i = 0; i < NR_CPUS; i++)
165 		cpufreq_thermal_reduction_pctg[i] = 0;
166 
167 	i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
168 				      CPUFREQ_POLICY_NOTIFIER);
169 	if (!i)
170 		acpi_thermal_cpufreq_is_init = 1;
171 }
172 
173 void acpi_thermal_cpufreq_exit(void)
174 {
175 	if (acpi_thermal_cpufreq_is_init)
176 		cpufreq_unregister_notifier
177 		    (&acpi_thermal_cpufreq_notifier_block,
178 		     CPUFREQ_POLICY_NOTIFIER);
179 
180 	acpi_thermal_cpufreq_is_init = 0;
181 }
182 
183 #else				/* ! CONFIG_CPU_FREQ */
184 
185 static int acpi_thermal_cpufreq_increase(unsigned int cpu)
186 {
187 	return -ENODEV;
188 }
189 static int acpi_thermal_cpufreq_decrease(unsigned int cpu)
190 {
191 	return -ENODEV;
192 }
193 
194 #endif
195 
196 int acpi_processor_set_thermal_limit(acpi_handle handle, int type)
197 {
198 	int result = 0;
199 	struct acpi_processor *pr = NULL;
200 	struct acpi_device *device = NULL;
201 	int tx = 0, max_tx_px = 0;
202 
203 	ACPI_FUNCTION_TRACE("acpi_processor_set_thermal_limit");
204 
205 	if ((type < ACPI_PROCESSOR_LIMIT_NONE)
206 	    || (type > ACPI_PROCESSOR_LIMIT_DECREMENT))
207 		return_VALUE(-EINVAL);
208 
209 	result = acpi_bus_get_device(handle, &device);
210 	if (result)
211 		return_VALUE(result);
212 
213 	pr = (struct acpi_processor *)acpi_driver_data(device);
214 	if (!pr)
215 		return_VALUE(-ENODEV);
216 
217 	/* Thermal limits are always relative to the current Px/Tx state. */
218 	if (pr->flags.throttling)
219 		pr->limit.thermal.tx = pr->throttling.state;
220 
221 	/*
222 	 * Our default policy is to only use throttling at the lowest
223 	 * performance state.
224 	 */
225 
226 	tx = pr->limit.thermal.tx;
227 
228 	switch (type) {
229 
230 	case ACPI_PROCESSOR_LIMIT_NONE:
231 		do {
232 			result = acpi_thermal_cpufreq_decrease(pr->id);
233 		} while (!result);
234 		tx = 0;
235 		break;
236 
237 	case ACPI_PROCESSOR_LIMIT_INCREMENT:
238 		/* if going up: P-states first, T-states later */
239 
240 		result = acpi_thermal_cpufreq_increase(pr->id);
241 		if (!result)
242 			goto end;
243 		else if (result == -ERANGE)
244 			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
245 					  "At maximum performance state\n"));
246 
247 		if (pr->flags.throttling) {
248 			if (tx == (pr->throttling.state_count - 1))
249 				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
250 						  "At maximum throttling state\n"));
251 			else
252 				tx++;
253 		}
254 		break;
255 
256 	case ACPI_PROCESSOR_LIMIT_DECREMENT:
257 		/* if going down: T-states first, P-states later */
258 
259 		if (pr->flags.throttling) {
260 			if (tx == 0) {
261 				max_tx_px = 1;
262 				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
263 						  "At minimum throttling state\n"));
264 			} else {
265 				tx--;
266 				goto end;
267 			}
268 		}
269 
270 		result = acpi_thermal_cpufreq_decrease(pr->id);
271 		if (result) {
272 			/*
273 			 * We only could get -ERANGE, 1 or 0.
274 			 * In the first two cases we reached max freq again.
275 			 */
276 			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
277 					  "At minimum performance state\n"));
278 			max_tx_px = 1;
279 		} else
280 			max_tx_px = 0;
281 
282 		break;
283 	}
284 
285       end:
286 	if (pr->flags.throttling) {
287 		pr->limit.thermal.px = 0;
288 		pr->limit.thermal.tx = tx;
289 
290 		result = acpi_processor_apply_limit(pr);
291 		if (result)
292 			ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
293 					  "Unable to set thermal limit\n"));
294 
295 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Thermal limit now (P%d:T%d)\n",
296 				  pr->limit.thermal.px, pr->limit.thermal.tx));
297 	} else
298 		result = 0;
299 	if (max_tx_px)
300 		return_VALUE(1);
301 	else
302 		return_VALUE(result);
303 }
304 
305 int acpi_processor_get_limit_info(struct acpi_processor *pr)
306 {
307 	ACPI_FUNCTION_TRACE("acpi_processor_get_limit_info");
308 
309 	if (!pr)
310 		return_VALUE(-EINVAL);
311 
312 	if (pr->flags.throttling)
313 		pr->flags.limit = 1;
314 
315 	return_VALUE(0);
316 }
317 
318 /* /proc interface */
319 
320 static int acpi_processor_limit_seq_show(struct seq_file *seq, void *offset)
321 {
322 	struct acpi_processor *pr = (struct acpi_processor *)seq->private;
323 
324 	ACPI_FUNCTION_TRACE("acpi_processor_limit_seq_show");
325 
326 	if (!pr)
327 		goto end;
328 
329 	if (!pr->flags.limit) {
330 		seq_puts(seq, "<not supported>\n");
331 		goto end;
332 	}
333 
334 	seq_printf(seq, "active limit:            P%d:T%d\n"
335 		   "user limit:              P%d:T%d\n"
336 		   "thermal limit:           P%d:T%d\n",
337 		   pr->limit.state.px, pr->limit.state.tx,
338 		   pr->limit.user.px, pr->limit.user.tx,
339 		   pr->limit.thermal.px, pr->limit.thermal.tx);
340 
341       end:
342 	return_VALUE(0);
343 }
344 
345 static int acpi_processor_limit_open_fs(struct inode *inode, struct file *file)
346 {
347 	return single_open(file, acpi_processor_limit_seq_show,
348 			   PDE(inode)->data);
349 }
350 
351 ssize_t acpi_processor_write_limit(struct file * file,
352 				   const char __user * buffer,
353 				   size_t count, loff_t * data)
354 {
355 	int result = 0;
356 	struct seq_file *m = (struct seq_file *)file->private_data;
357 	struct acpi_processor *pr = (struct acpi_processor *)m->private;
358 	char limit_string[25] = { '\0' };
359 	int px = 0;
360 	int tx = 0;
361 
362 	ACPI_FUNCTION_TRACE("acpi_processor_write_limit");
363 
364 	if (!pr || (count > sizeof(limit_string) - 1)) {
365 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid argument\n"));
366 		return_VALUE(-EINVAL);
367 	}
368 
369 	if (copy_from_user(limit_string, buffer, count)) {
370 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid data\n"));
371 		return_VALUE(-EFAULT);
372 	}
373 
374 	limit_string[count] = '\0';
375 
376 	if (sscanf(limit_string, "%d:%d", &px, &tx) != 2) {
377 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid data format\n"));
378 		return_VALUE(-EINVAL);
379 	}
380 
381 	if (pr->flags.throttling) {
382 		if ((tx < 0) || (tx > (pr->throttling.state_count - 1))) {
383 			ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid tx\n"));
384 			return_VALUE(-EINVAL);
385 		}
386 		pr->limit.user.tx = tx;
387 	}
388 
389 	result = acpi_processor_apply_limit(pr);
390 
391 	return_VALUE(count);
392 }
393 
394 struct file_operations acpi_processor_limit_fops = {
395 	.open = acpi_processor_limit_open_fs,
396 	.read = seq_read,
397 	.llseek = seq_lseek,
398 	.release = single_release,
399 };
400