drivers/acpi/processor_throttling.c

   1 /*
   2  * processor_throttling.c - Throttling 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/io.h>
  37 #include <asm/uaccess.h>
  38
  39 #include <acpi/acpi_bus.h>
  40 #include <acpi/processor.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 /* --------------------------------------------------------------------------
  50                               Throttling Control
  51    -------------------------------------------------------------------------- */
  52
  53 static int
  54 acpi_processor_get_throttling (
  55         struct acpi_processor   *pr)
  56 {
  57         int                     state = 0;
  58         u32                     value = 0;
  59         u32                     duty_mask = 0;
  60         u32                     duty_value = 0;
  61
  62         ACPI_FUNCTION_TRACE("acpi_processor_get_throttling");
  63
  64         if (!pr)
  65                 return_VALUE(-EINVAL);
  66
  67         if (!pr->flags.throttling)
  68                 return_VALUE(-ENODEV);
  69
  70         pr->throttling.state = 0;
  71
  72         duty_mask = pr->throttling.state_count - 1;
  73
  74         duty_mask <<= pr->throttling.duty_offset;
  75
  76         local_irq_disable();
  77
  78         value = inl(pr->throttling.address);
  79
  80         /*
  81          * Compute the current throttling state when throttling is enabled
  82          * (bit 4 is on).
  83          */
  84         if (value & 0x10) {
  85                 duty_value = value & duty_mask;
  86                 duty_value >>= pr->throttling.duty_offset;
  87
  88                 if (duty_value)
  89                         state = pr->throttling.state_count-duty_value;
  90         }
  91
  92         pr->throttling.state = state;
  93
  94         local_irq_enable();
  95
  96         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  97                 "Throttling state is T%d (%d%% throttling applied)\n",
  98                 state, pr->throttling.states[state].performance));
  99
 100         return_VALUE(0);
 101 }
 102
 103
 104 int acpi_processor_set_throttling (
 105         struct acpi_processor   *pr,
 106         int                     state)
 107 {
 108         u32                     value = 0;
 109         u32                     duty_mask = 0;
 110         u32                     duty_value = 0;
 111
 112         ACPI_FUNCTION_TRACE("acpi_processor_set_throttling");
 113
 114         if (!pr)
 115                 return_VALUE(-EINVAL);
 116
 117         if ((state < 0) || (state > (pr->throttling.state_count - 1)))
 118                 return_VALUE(-EINVAL);
 119
 120         if (!pr->flags.throttling)
 121                 return_VALUE(-ENODEV);
 122
 123         if (state == pr->throttling.state)
 124                 return_VALUE(0);
 125
 126         /*
 127          * Calculate the duty_value and duty_mask.
 128          */
 129         if (state) {
 130                 duty_value = pr->throttling.state_count - state;
 131
 132                 duty_value <<= pr->throttling.duty_offset;
 133
 134                 /* Used to clear all duty_value bits */
 135                 duty_mask = pr->throttling.state_count - 1;
 136
 137                 duty_mask <<= acpi_fadt.duty_offset;
 138                 duty_mask = ~duty_mask;
 139         }
 140
 141         local_irq_disable();
 142
 143         /*
 144          * Disable throttling by writing a 0 to bit 4.  Note that we must
 145          * turn it off before you can change the duty_value.
 146          */
 147         value = inl(pr->throttling.address);
 148         if (value & 0x10) {
 149                 value &= 0xFFFFFFEF;
 150                 outl(value, pr->throttling.address);
 151         }
 152
 153         /*
 154          * Write the new duty_value and then enable throttling.  Note
 155          * that a state value of 0 leaves throttling disabled.
 156          */
 157         if (state) {
 158                 value &= duty_mask;
 159                 value |= duty_value;
 160                 outl(value, pr->throttling.address);
 161
 162                 value |= 0x00000010;
 163                 outl(value, pr->throttling.address);
 164         }
 165
 166         pr->throttling.state = state;
 167
 168         local_irq_enable();
 169
 170         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 171                 "Throttling state set to T%d (%d%%)\n", state,
 172                 (pr->throttling.states[state].performance?pr->throttling.states[state].performance/10:0)));
 173
 174         return_VALUE(0);
 175 }
 176
 177
 178 int
 179 acpi_processor_get_throttling_info (
 180         struct acpi_processor   *pr)
 181 {
 182         int                     result = 0;
 183         int                     step = 0;
 184         int                     i = 0;
 185
 186         ACPI_FUNCTION_TRACE("acpi_processor_get_throttling_info");
 187
 188         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 189                 "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
 190                 pr->throttling.address,
 191                 pr->throttling.duty_offset,
 192                 pr->throttling.duty_width));
 193
 194         if (!pr)
 195                 return_VALUE(-EINVAL);
 196
 197         /* TBD: Support ACPI 2.0 objects */
 198
 199         if (!pr->throttling.address) {
 200                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
 201                 return_VALUE(0);
 202         }
 203         else if (!pr->throttling.duty_width) {
 204                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
 205                 return_VALUE(0);
 206         }
 207         /* TBD: Support duty_cycle values that span bit 4. */
 208         else if ((pr->throttling.duty_offset
 209                 + pr->throttling.duty_width) > 4) {
 210                 ACPI_DEBUG_PRINT((ACPI_DB_WARN, "duty_cycle spans bit 4\n"));
 211                 return_VALUE(0);
 212         }
 213
 214         /*
 215          * PIIX4 Errata: We don't support throttling on the original PIIX4.
 216          * This shouldn't be an issue as few (if any) mobile systems ever
 217          * used this part.
 218          */
 219         if (errata.piix4.throttle) {
 220                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 221                         "Throttling not supported on PIIX4 A- or B-step\n"));
 222                 return_VALUE(0);
 223         }
 224
 225         pr->throttling.state_count = 1 << acpi_fadt.duty_width;
 226
 227         /*
 228          * Compute state values. Note that throttling displays a linear power/
 229          * performance relationship (at 50% performance the CPU will consume
 230          * 50% power).  Values are in 1/10th of a percent to preserve accuracy.
 231          */
 232
 233         step = (1000 / pr->throttling.state_count);
 234
 235         for (i=0; i<pr->throttling.state_count; i++) {
 236                 pr->throttling.states[i].performance = step * i;
 237                 pr->throttling.states[i].power = step * i;
 238         }
 239
 240         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
 241                 pr->throttling.state_count));
 242
 243         pr->flags.throttling = 1;
 244
 245         /*
 246          * Disable throttling (if enabled).  We'll let subsequent policy (e.g.
 247          * thermal) decide to lower performance if it so chooses, but for now
 248          * we'll crank up the speed.
 249          */
 250
 251         result = acpi_processor_get_throttling(pr);
 252         if (result)
 253                 goto end;
 254
 255         if (pr->throttling.state) {
 256                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Disabling throttling (was T%d)\n",
 257                         pr->throttling.state));
 258                 result = acpi_processor_set_throttling(pr, 0);
 259                 if (result)
 260                         goto end;
 261         }
 262
 263 end:
 264         if (result)
 265                 pr->flags.throttling = 0;
 266
 267         return_VALUE(result);
 268 }
 269
 270
 271 /* proc interface */
 272
 273 static int acpi_processor_throttling_seq_show(struct seq_file *seq, void *offset)
 274 {
 275         struct acpi_processor   *pr = (struct acpi_processor *)seq->private;
 276         int                     i = 0;
 277         int                     result = 0;
 278
 279         ACPI_FUNCTION_TRACE("acpi_processor_throttling_seq_show");
 280
 281         if (!pr)
 282                 goto end;
 283
 284         if (!(pr->throttling.state_count > 0)) {
 285                 seq_puts(seq, "<not supported>\n");
 286                 goto end;
 287         }
 288
 289         result = acpi_processor_get_throttling(pr);
 290
 291         if (result) {
 292                 seq_puts(seq, "Could not determine current throttling state.\n");
 293                 goto end;
 294         }
 295
 296         seq_printf(seq, "state count:             %d\n"
 297                         "active state:            T%d\n",
 298                         pr->throttling.state_count,
 299                         pr->throttling.state);
 300
 301         seq_puts(seq, "states:\n");
 302         for (i = 0; i < pr->throttling.state_count; i++)
 303                 seq_printf(seq, "   %cT%d:                  %02d%%\n",
 304                         (i == pr->throttling.state?'*':' '), i,
 305                         (pr->throttling.states[i].performance?pr->throttling.states[i].performance/10:0));
 306
 307 end:
 308         return_VALUE(0);
 309 }
 310
 311 static int acpi_processor_throttling_open_fs(struct inode *inode, struct file *file)
 312 {
 313         return single_open(file, acpi_processor_throttling_seq_show,
 314                                                 PDE(inode)->data);
 315 }
 316
 317 ssize_t acpi_processor_write_throttling (
 318         struct file             *file,
 319         const char              __user *buffer,
 320         size_t                  count,
 321         loff_t                  *data)
 322 {
 323         int                     result = 0;
 324         struct seq_file         *m = (struct seq_file *)file->private_data;
 325         struct acpi_processor   *pr = (struct acpi_processor *)m->private;
 326         char                    state_string[12] = {'\0'};
 327
 328         ACPI_FUNCTION_TRACE("acpi_processor_write_throttling");
 329
 330         if (!pr || (count > sizeof(state_string) - 1))
 331                 return_VALUE(-EINVAL);
 332
 333         if (copy_from_user(state_string, buffer, count))
 334                 return_VALUE(-EFAULT);
 335
 336         state_string[count] = '\0';
 337
 338         result = acpi_processor_set_throttling(pr,
 339                 simple_strtoul(state_string, NULL, 0));
 340         if (result)
 341                 return_VALUE(result);
 342
 343         return_VALUE(count);
 344 }
 345
 346 struct file_operations acpi_processor_throttling_fops = {
 347         .open           = acpi_processor_throttling_open_fs,
 348         .read           = seq_read,
 349         .llseek         = seq_lseek,
 350         .release        = single_release,
 351 };