drivers/acpi/processor_thermal.c

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