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 _COMPONENT              ACPI_PROCESSOR_COMPONENT
  45 ACPI_MODULE_NAME("processor_throttling");
  46
  47 /* --------------------------------------------------------------------------
  48                               Throttling Control
  49    -------------------------------------------------------------------------- */
  50 static int acpi_processor_get_throttling(struct acpi_processor *pr)
  51 {
  52         int state = 0;
  53         u32 value = 0;
  54         u32 duty_mask = 0;
  55         u32 duty_value = 0;
  56
  57
  58         if (!pr)
  59                 return -EINVAL;
  60
  61         if (!pr->flags.throttling)
  62                 return -ENODEV;
  63
  64         pr->throttling.state = 0;
  65
  66         duty_mask = pr->throttling.state_count - 1;
  67
  68         duty_mask <<= pr->throttling.duty_offset;
  69
  70         local_irq_disable();
  71
  72         value = inl(pr->throttling.address);
  73
  74         /*
  75          * Compute the current throttling state when throttling is enabled
  76          * (bit 4 is on).
  77          */
  78         if (value & 0x10) {
  79                 duty_value = value & duty_mask;
  80                 duty_value >>= pr->throttling.duty_offset;
  81
  82                 if (duty_value)
  83                         state = pr->throttling.state_count - duty_value;
  84         }
  85
  86         pr->throttling.state = state;
  87
  88         local_irq_enable();
  89
  90         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  91                           "Throttling state is T%d (%d%% throttling applied)\n",
  92                           state, pr->throttling.states[state].performance));
  93
  94         return 0;
  95 }
  96
  97 int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
  98 {
  99         u32 value = 0;
 100         u32 duty_mask = 0;
 101         u32 duty_value = 0;
 102
 103
 104         if (!pr)
 105                 return -EINVAL;
 106
 107         if ((state < 0) || (state > (pr->throttling.state_count - 1)))
 108                 return -EINVAL;
 109
 110         if (!pr->flags.throttling)
 111                 return -ENODEV;
 112
 113         if (state == pr->throttling.state)
 114                 return 0;
 115
 116         /*
 117          * Calculate the duty_value and duty_mask.
 118          */
 119         if (state) {
 120                 duty_value = pr->throttling.state_count - state;
 121
 122                 duty_value <<= pr->throttling.duty_offset;
 123
 124                 /* Used to clear all duty_value bits */
 125                 duty_mask = pr->throttling.state_count - 1;
 126
 127                 duty_mask <<= acpi_gbl_FADT.duty_offset;
 128                 duty_mask = ~duty_mask;
 129         }
 130
 131         local_irq_disable();
 132
 133         /*
 134          * Disable throttling by writing a 0 to bit 4.  Note that we must
 135          * turn it off before you can change the duty_value.
 136          */
 137         value = inl(pr->throttling.address);
 138         if (value & 0x10) {
 139                 value &= 0xFFFFFFEF;
 140                 outl(value, pr->throttling.address);
 141         }
 142
 143         /*
 144          * Write the new duty_value and then enable throttling.  Note
 145          * that a state value of 0 leaves throttling disabled.
 146          */
 147         if (state) {
 148                 value &= duty_mask;
 149                 value |= duty_value;
 150                 outl(value, pr->throttling.address);
 151
 152                 value |= 0x00000010;
 153                 outl(value, pr->throttling.address);
 154         }
 155
 156         pr->throttling.state = state;
 157
 158         local_irq_enable();
 159
 160         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 161                           "Throttling state set to T%d (%d%%)\n", state,
 162                           (pr->throttling.states[state].performance ? pr->
 163                            throttling.states[state].performance / 10 : 0)));
 164
 165         return 0;
 166 }
 167
 168 int acpi_processor_get_throttling_info(struct acpi_processor *pr)
 169 {
 170         int result = 0;
 171         int step = 0;
 172         int i = 0;
 173
 174
 175         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 176                           "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
 177                           pr->throttling.address,
 178                           pr->throttling.duty_offset,
 179                           pr->throttling.duty_width));
 180
 181         if (!pr)
 182                 return -EINVAL;
 183
 184         /* TBD: Support ACPI 2.0 objects */
 185
 186         if (!pr->throttling.address) {
 187                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
 188                 return 0;
 189         } else if (!pr->throttling.duty_width) {
 190                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
 191                 return 0;
 192         }
 193         /* TBD: Support duty_cycle values that span bit 4. */
 194         else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
 195                 printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
 196                 return 0;
 197         }
 198
 199         /*
 200          * PIIX4 Errata: We don't support throttling on the original PIIX4.
 201          * This shouldn't be an issue as few (if any) mobile systems ever
 202          * used this part.
 203          */
 204         if (errata.piix4.throttle) {
 205                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 206                                   "Throttling not supported on PIIX4 A- or B-step\n"));
 207                 return 0;
 208         }
 209
 210         pr->throttling.state_count = 1 << acpi_gbl_FADT.duty_width;
 211
 212         /*
 213          * Compute state values. Note that throttling displays a linear power/
 214          * performance relationship (at 50% performance the CPU will consume
 215          * 50% power).  Values are in 1/10th of a percent to preserve accuracy.
 216          */
 217
 218         step = (1000 / pr->throttling.state_count);
 219
 220         for (i = 0; i < pr->throttling.state_count; i++) {
 221                 pr->throttling.states[i].performance = step * i;
 222                 pr->throttling.states[i].power = step * i;
 223         }
 224
 225         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
 226                           pr->throttling.state_count));
 227
 228         pr->flags.throttling = 1;
 229
 230         /*
 231          * Disable throttling (if enabled).  We'll let subsequent policy (e.g.
 232          * thermal) decide to lower performance if it so chooses, but for now
 233          * we'll crank up the speed.
 234          */
 235
 236         result = acpi_processor_get_throttling(pr);
 237         if (result)
 238                 goto end;
 239
 240         if (pr->throttling.state) {
 241                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 242                                   "Disabling throttling (was T%d)\n",
 243                                   pr->throttling.state));
 244                 result = acpi_processor_set_throttling(pr, 0);
 245                 if (result)
 246                         goto end;
 247         }
 248
 249       end:
 250         if (result)
 251                 pr->flags.throttling = 0;
 252
 253         return result;
 254 }
 255
 256 /* proc interface */
 257
 258 static int acpi_processor_throttling_seq_show(struct seq_file *seq,
 259                                               void *offset)
 260 {
 261         struct acpi_processor *pr = seq->private;
 262         int i = 0;
 263         int result = 0;
 264
 265
 266         if (!pr)
 267                 goto end;
 268
 269         if (!(pr->throttling.state_count > 0)) {
 270                 seq_puts(seq, "<not supported>\n");
 271                 goto end;
 272         }
 273
 274         result = acpi_processor_get_throttling(pr);
 275
 276         if (result) {
 277                 seq_puts(seq,
 278                          "Could not determine current throttling state.\n");
 279                 goto end;
 280         }
 281
 282         seq_printf(seq, "state count:             %d\n"
 283                    "active state:            T%d\n",
 284                    pr->throttling.state_count, pr->throttling.state);
 285
 286         seq_puts(seq, "states:\n");
 287         for (i = 0; i < pr->throttling.state_count; i++)
 288                 seq_printf(seq, "   %cT%d:                  %02d%%\n",
 289                            (i == pr->throttling.state ? '*' : ' '), i,
 290                            (pr->throttling.states[i].performance ? pr->
 291                             throttling.states[i].performance / 10 : 0));
 292
 293       end:
 294         return 0;
 295 }
 296
 297 static int acpi_processor_throttling_open_fs(struct inode *inode,
 298                                              struct file *file)
 299 {
 300         return single_open(file, acpi_processor_throttling_seq_show,
 301                            PDE(inode)->data);
 302 }
 303
 304 static ssize_t acpi_processor_write_throttling(struct file * file,
 305                                                const char __user * buffer,
 306                                                size_t count, loff_t * data)
 307 {
 308         int result = 0;
 309         struct seq_file *m = file->private_data;
 310         struct acpi_processor *pr = m->private;
 311         char state_string[12] = { '\0' };
 312
 313
 314         if (!pr || (count > sizeof(state_string) - 1))
 315                 return -EINVAL;
 316
 317         if (copy_from_user(state_string, buffer, count))
 318                 return -EFAULT;
 319
 320         state_string[count] = '\0';
 321
 322         result = acpi_processor_set_throttling(pr,
 323                                                simple_strtoul(state_string,
 324                                                               NULL, 0));
 325         if (result)
 326                 return result;
 327
 328         return count;
 329 }
 330
 331 struct file_operations acpi_processor_throttling_fops = {
 332         .open = acpi_processor_throttling_open_fs,
 333         .read = seq_read,
 334         .write = acpi_processor_write_throttling,
 335         .llseek = seq_lseek,
 336         .release = single_release,
 337 };