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 _COMPONENT              ACPI_PROCESSOR_COMPONENT
45ACPI_MODULE_NAME("processor_thermal");
46
47/* --------------------------------------------------------------------------
48                                 Limit Interface
49   -------------------------------------------------------------------------- */
50static int acpi_processor_apply_limit(struct acpi_processor *pr)
51{
52	int result = 0;
53	u16 px = 0;
54	u16 tx = 0;
55
56
57	if (!pr)
58		return -EINVAL;
59
60	if (!pr->flags.limit)
61		return -ENODEV;
62
63	if (pr->flags.throttling) {
64		if (pr->limit.user.tx > tx)
65			tx = pr->limit.user.tx;
66		if (pr->limit.thermal.tx > tx)
67			tx = pr->limit.thermal.tx;
68
69		result = acpi_processor_set_throttling(pr, tx);
70		if (result)
71			goto end;
72	}
73
74	pr->limit.state.px = px;
75	pr->limit.state.tx = tx;
76
77	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
78			  "Processor [%d] limit set to (P%d:T%d)\n", pr->id,
79			  pr->limit.state.px, pr->limit.state.tx));
80
81      end:
82	if (result)
83		printk(KERN_ERR PREFIX "Unable to set limit\n");
84
85	return result;
86}
87
88#ifdef CONFIG_CPU_FREQ
89
90/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
91 * offers (in most cases) voltage scaling in addition to frequency scaling, and
92 * thus a cubic (instead of linear) reduction of energy. Also, we allow for
93 * _any_ cpufreq driver and not only the acpi-cpufreq driver.
94 */
95
96static unsigned int cpufreq_thermal_reduction_pctg[NR_CPUS];
97static unsigned int acpi_thermal_cpufreq_is_init = 0;
98
99static int cpu_has_cpufreq(unsigned int cpu)
100{
101	struct cpufreq_policy policy;
102	if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
103		return 0;
104	return 1;
105}
106
107static int acpi_thermal_cpufreq_increase(unsigned int cpu)
108{
109	if (!cpu_has_cpufreq(cpu))
110		return -ENODEV;
111
112	if (cpufreq_thermal_reduction_pctg[cpu] < 60) {
113		cpufreq_thermal_reduction_pctg[cpu] += 20;
114		cpufreq_update_policy(cpu);
115		return 0;
116	}
117
118	return -ERANGE;
119}
120
121static int acpi_thermal_cpufreq_decrease(unsigned int cpu)
122{
123	if (!cpu_has_cpufreq(cpu))
124		return -ENODEV;
125
126	if (cpufreq_thermal_reduction_pctg[cpu] > 20)
127		cpufreq_thermal_reduction_pctg[cpu] -= 20;
128	else
129		cpufreq_thermal_reduction_pctg[cpu] = 0;
130	cpufreq_update_policy(cpu);
131	/* We reached max freq again and can leave passive mode */
132	return !cpufreq_thermal_reduction_pctg[cpu];
133}
134
135static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
136					 unsigned long event, void *data)
137{
138	struct cpufreq_policy *policy = data;
139	unsigned long max_freq = 0;
140
141	if (event != CPUFREQ_ADJUST)
142		goto out;
143
144	max_freq =
145	    (policy->cpuinfo.max_freq *
146	     (100 - cpufreq_thermal_reduction_pctg[policy->cpu])) / 100;
147
148	cpufreq_verify_within_limits(policy, 0, max_freq);
149
150      out:
151	return 0;
152}
153
154static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
155	.notifier_call = acpi_thermal_cpufreq_notifier,
156};
157
158void acpi_thermal_cpufreq_init(void)
159{
160	int i;
161
162	for (i = 0; i < NR_CPUS; i++)
163		cpufreq_thermal_reduction_pctg[i] = 0;
164
165	i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
166				      CPUFREQ_POLICY_NOTIFIER);
167	if (!i)
168		acpi_thermal_cpufreq_is_init = 1;
169}
170
171void acpi_thermal_cpufreq_exit(void)
172{
173	if (acpi_thermal_cpufreq_is_init)
174		cpufreq_unregister_notifier
175		    (&acpi_thermal_cpufreq_notifier_block,
176		     CPUFREQ_POLICY_NOTIFIER);
177
178	acpi_thermal_cpufreq_is_init = 0;
179}
180
181#else				/* ! CONFIG_CPU_FREQ */
182
183static int acpi_thermal_cpufreq_increase(unsigned int cpu)
184{
185	return -ENODEV;
186}
187static int acpi_thermal_cpufreq_decrease(unsigned int cpu)
188{
189	return -ENODEV;
190}
191
192#endif
193
194int acpi_processor_set_thermal_limit(acpi_handle handle, int type)
195{
196	int result = 0;
197	struct acpi_processor *pr = NULL;
198	struct acpi_device *device = NULL;
199	int tx = 0, max_tx_px = 0;
200
201
202	if ((type < ACPI_PROCESSOR_LIMIT_NONE)
203	    || (type > ACPI_PROCESSOR_LIMIT_DECREMENT))
204		return -EINVAL;
205
206	result = acpi_bus_get_device(handle, &device);
207	if (result)
208		return result;
209
210	pr = acpi_driver_data(device);
211	if (!pr)
212		return -ENODEV;
213
214	/* Thermal limits are always relative to the current Px/Tx state. */
215	if (pr->flags.throttling)
216		pr->limit.thermal.tx = pr->throttling.state;
217
218	/*
219	 * Our default policy is to only use throttling at the lowest
220	 * performance state.
221	 */
222
223	tx = pr->limit.thermal.tx;
224
225	switch (type) {
226
227	case ACPI_PROCESSOR_LIMIT_NONE:
228		do {
229			result = acpi_thermal_cpufreq_decrease(pr->id);
230		} while (!result);
231		tx = 0;
232		break;
233
234	case ACPI_PROCESSOR_LIMIT_INCREMENT:
235		/* if going up: P-states first, T-states later */
236
237		result = acpi_thermal_cpufreq_increase(pr->id);
238		if (!result)
239			goto end;
240		else if (result == -ERANGE)
241			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
242					  "At maximum performance state\n"));
243
244		if (pr->flags.throttling) {
245			if (tx == (pr->throttling.state_count - 1))
246				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
247						  "At maximum throttling state\n"));
248			else
249				tx++;
250		}
251		break;
252
253	case ACPI_PROCESSOR_LIMIT_DECREMENT:
254		/* if going down: T-states first, P-states later */
255
256		if (pr->flags.throttling) {
257			if (tx == 0) {
258				max_tx_px = 1;
259				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
260						  "At minimum throttling state\n"));
261			} else {
262				tx--;
263				goto end;
264			}
265		}
266
267		result = acpi_thermal_cpufreq_decrease(pr->id);
268		if (result) {
269			/*
270			 * We only could get -ERANGE, 1 or 0.
271			 * In the first two cases we reached max freq again.
272			 */
273			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
274					  "At minimum performance state\n"));
275			max_tx_px = 1;
276		} else
277			max_tx_px = 0;
278
279		break;
280	}
281
282      end:
283	if (pr->flags.throttling) {
284		pr->limit.thermal.px = 0;
285		pr->limit.thermal.tx = tx;
286
287		result = acpi_processor_apply_limit(pr);
288		if (result)
289			printk(KERN_ERR PREFIX "Unable to set thermal limit\n");
290
291		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Thermal limit now (P%d:T%d)\n",
292				  pr->limit.thermal.px, pr->limit.thermal.tx));
293	} else
294		result = 0;
295	if (max_tx_px)
296		return 1;
297	else
298		return result;
299}
300
301int acpi_processor_get_limit_info(struct acpi_processor *pr)
302{
303
304	if (!pr)
305		return -EINVAL;
306
307	if (pr->flags.throttling)
308		pr->flags.limit = 1;
309
310	return 0;
311}
312
313/* /proc interface */
314
315static int acpi_processor_limit_seq_show(struct seq_file *seq, void *offset)
316{
317	struct acpi_processor *pr = (struct acpi_processor *)seq->private;
318
319
320	if (!pr)
321		goto end;
322
323	if (!pr->flags.limit) {
324		seq_puts(seq, "<not supported>\n");
325		goto end;
326	}
327
328	seq_printf(seq, "active limit:            P%d:T%d\n"
329		   "user limit:              P%d:T%d\n"
330		   "thermal limit:           P%d:T%d\n",
331		   pr->limit.state.px, pr->limit.state.tx,
332		   pr->limit.user.px, pr->limit.user.tx,
333		   pr->limit.thermal.px, pr->limit.thermal.tx);
334
335      end:
336	return 0;
337}
338
339static int acpi_processor_limit_open_fs(struct inode *inode, struct file *file)
340{
341	return single_open(file, acpi_processor_limit_seq_show,
342			   PDE(inode)->data);
343}
344
345static ssize_t acpi_processor_write_limit(struct file * file,
346					  const char __user * buffer,
347					  size_t count, loff_t * data)
348{
349	int result = 0;
350	struct seq_file *m = file->private_data;
351	struct acpi_processor *pr = m->private;
352	char limit_string[25] = { '\0' };
353	int px = 0;
354	int tx = 0;
355
356
357	if (!pr || (count > sizeof(limit_string) - 1)) {
358		return -EINVAL;
359	}
360
361	if (copy_from_user(limit_string, buffer, count)) {
362		return -EFAULT;
363	}
364
365	limit_string[count] = '\0';
366
367	if (sscanf(limit_string, "%d:%d", &px, &tx) != 2) {
368		printk(KERN_ERR PREFIX "Invalid data format\n");
369		return -EINVAL;
370	}
371
372	if (pr->flags.throttling) {
373		if ((tx < 0) || (tx > (pr->throttling.state_count - 1))) {
374			printk(KERN_ERR PREFIX "Invalid tx\n");
375			return -EINVAL;
376		}
377		pr->limit.user.tx = tx;
378	}
379
380	result = acpi_processor_apply_limit(pr);
381
382	return count;
383}
384
385struct file_operations acpi_processor_limit_fops = {
386	.open = acpi_processor_limit_open_fs,
387	.read = seq_read,
388	.write = acpi_processor_write_limit,
389	.llseek = seq_lseek,
390	.release = single_release,
391};
392