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