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