linux/drivers/cpufreq/pcc-cpufreq.c
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   1/*
   2 *  pcc-cpufreq.c - Processor Clocking Control firmware cpufreq interface
   3 *
   4 *  Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
   5 *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   6 *      Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
   7 *
   8 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   9 *
  10 *  This program is free software; you can redistribute it and/or modify
  11 *  it under the terms of the GNU General Public License as published by
  12 *  the Free Software Foundation; version 2 of the License.
  13 *
  14 *  This program is distributed in the hope that it will be useful, but
  15 *  WITHOUT ANY WARRANTY; without even the implied warranty of
  16 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or NON
  17 *  INFRINGEMENT. See the GNU General Public License for more details.
  18 *
  19 *  You should have received a copy of the GNU General Public License along
  20 *  with this program; if not, write to the Free Software Foundation, Inc.,
  21 *  675 Mass Ave, Cambridge, MA 02139, USA.
  22 *
  23 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24 */
  25
  26#include <linux/kernel.h>
  27#include <linux/module.h>
  28#include <linux/init.h>
  29#include <linux/smp.h>
  30#include <linux/sched.h>
  31#include <linux/cpufreq.h>
  32#include <linux/compiler.h>
  33#include <linux/slab.h>
  34
  35#include <linux/acpi.h>
  36#include <linux/io.h>
  37#include <linux/spinlock.h>
  38#include <linux/uaccess.h>
  39
  40#include <acpi/processor.h>
  41
  42#define PCC_VERSION     "1.10.00"
  43#define POLL_LOOPS      300
  44
  45#define CMD_COMPLETE    0x1
  46#define CMD_GET_FREQ    0x0
  47#define CMD_SET_FREQ    0x1
  48
  49#define BUF_SZ          4
  50
  51struct pcc_register_resource {
  52        u8 descriptor;
  53        u16 length;
  54        u8 space_id;
  55        u8 bit_width;
  56        u8 bit_offset;
  57        u8 access_size;
  58        u64 address;
  59} __attribute__ ((packed));
  60
  61struct pcc_memory_resource {
  62        u8 descriptor;
  63        u16 length;
  64        u8 space_id;
  65        u8 resource_usage;
  66        u8 type_specific;
  67        u64 granularity;
  68        u64 minimum;
  69        u64 maximum;
  70        u64 translation_offset;
  71        u64 address_length;
  72} __attribute__ ((packed));
  73
  74static struct cpufreq_driver pcc_cpufreq_driver;
  75
  76struct pcc_header {
  77        u32 signature;
  78        u16 length;
  79        u8 major;
  80        u8 minor;
  81        u32 features;
  82        u16 command;
  83        u16 status;
  84        u32 latency;
  85        u32 minimum_time;
  86        u32 maximum_time;
  87        u32 nominal;
  88        u32 throttled_frequency;
  89        u32 minimum_frequency;
  90};
  91
  92static void __iomem *pcch_virt_addr;
  93static struct pcc_header __iomem *pcch_hdr;
  94
  95static DEFINE_SPINLOCK(pcc_lock);
  96
  97static struct acpi_generic_address doorbell;
  98
  99static u64 doorbell_preserve;
 100static u64 doorbell_write;
 101
 102static u8 OSC_UUID[16] = {0x9F, 0x2C, 0x9B, 0x63, 0x91, 0x70, 0x1f, 0x49,
 103                          0xBB, 0x4F, 0xA5, 0x98, 0x2F, 0xA1, 0xB5, 0x46};
 104
 105struct pcc_cpu {
 106        u32 input_offset;
 107        u32 output_offset;
 108};
 109
 110static struct pcc_cpu __percpu *pcc_cpu_info;
 111
 112static int pcc_cpufreq_verify(struct cpufreq_policy *policy)
 113{
 114        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
 115                                     policy->cpuinfo.max_freq);
 116        return 0;
 117}
 118
 119static inline void pcc_cmd(void)
 120{
 121        u64 doorbell_value;
 122        int i;
 123
 124        acpi_read(&doorbell_value, &doorbell);
 125        acpi_write((doorbell_value & doorbell_preserve) | doorbell_write,
 126                   &doorbell);
 127
 128        for (i = 0; i < POLL_LOOPS; i++) {
 129                if (ioread16(&pcch_hdr->status) & CMD_COMPLETE)
 130                        break;
 131        }
 132}
 133
 134static inline void pcc_clear_mapping(void)
 135{
 136        if (pcch_virt_addr)
 137                iounmap(pcch_virt_addr);
 138        pcch_virt_addr = NULL;
 139}
 140
 141static unsigned int pcc_get_freq(unsigned int cpu)
 142{
 143        struct pcc_cpu *pcc_cpu_data;
 144        unsigned int curr_freq;
 145        unsigned int freq_limit;
 146        u16 status;
 147        u32 input_buffer;
 148        u32 output_buffer;
 149
 150        spin_lock(&pcc_lock);
 151
 152        pr_debug("get: get_freq for CPU %d\n", cpu);
 153        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 154
 155        input_buffer = 0x1;
 156        iowrite32(input_buffer,
 157                        (pcch_virt_addr + pcc_cpu_data->input_offset));
 158        iowrite16(CMD_GET_FREQ, &pcch_hdr->command);
 159
 160        pcc_cmd();
 161
 162        output_buffer =
 163                ioread32(pcch_virt_addr + pcc_cpu_data->output_offset);
 164
 165        /* Clear the input buffer - we are done with the current command */
 166        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 167
 168        status = ioread16(&pcch_hdr->status);
 169        if (status != CMD_COMPLETE) {
 170                pr_debug("get: FAILED: for CPU %d, status is %d\n",
 171                        cpu, status);
 172                goto cmd_incomplete;
 173        }
 174        iowrite16(0, &pcch_hdr->status);
 175        curr_freq = (((ioread32(&pcch_hdr->nominal) * (output_buffer & 0xff))
 176                        / 100) * 1000);
 177
 178        pr_debug("get: SUCCESS: (virtual) output_offset for cpu %d is "
 179                "0x%p, contains a value of: 0x%x. Speed is: %d MHz\n",
 180                cpu, (pcch_virt_addr + pcc_cpu_data->output_offset),
 181                output_buffer, curr_freq);
 182
 183        freq_limit = (output_buffer >> 8) & 0xff;
 184        if (freq_limit != 0xff) {
 185                pr_debug("get: frequency for cpu %d is being temporarily"
 186                        " capped at %d\n", cpu, curr_freq);
 187        }
 188
 189        spin_unlock(&pcc_lock);
 190        return curr_freq;
 191
 192cmd_incomplete:
 193        iowrite16(0, &pcch_hdr->status);
 194        spin_unlock(&pcc_lock);
 195        return 0;
 196}
 197
 198static int pcc_cpufreq_target(struct cpufreq_policy *policy,
 199                              unsigned int target_freq,
 200                              unsigned int relation)
 201{
 202        struct pcc_cpu *pcc_cpu_data;
 203        struct cpufreq_freqs freqs;
 204        u16 status;
 205        u32 input_buffer;
 206        int cpu;
 207
 208        spin_lock(&pcc_lock);
 209        cpu = policy->cpu;
 210        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 211
 212        pr_debug("target: CPU %d should go to target freq: %d "
 213                "(virtual) input_offset is 0x%p\n",
 214                cpu, target_freq,
 215                (pcch_virt_addr + pcc_cpu_data->input_offset));
 216
 217        freqs.new = target_freq;
 218        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 219
 220        input_buffer = 0x1 | (((target_freq * 100)
 221                               / (ioread32(&pcch_hdr->nominal) * 1000)) << 8);
 222        iowrite32(input_buffer,
 223                        (pcch_virt_addr + pcc_cpu_data->input_offset));
 224        iowrite16(CMD_SET_FREQ, &pcch_hdr->command);
 225
 226        pcc_cmd();
 227
 228        /* Clear the input buffer - we are done with the current command */
 229        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 230
 231        status = ioread16(&pcch_hdr->status);
 232        if (status != CMD_COMPLETE) {
 233                pr_debug("target: FAILED for cpu %d, with status: 0x%x\n",
 234                        cpu, status);
 235                goto cmd_incomplete;
 236        }
 237        iowrite16(0, &pcch_hdr->status);
 238
 239        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 240        pr_debug("target: was SUCCESSFUL for cpu %d\n", cpu);
 241        spin_unlock(&pcc_lock);
 242
 243        return 0;
 244
 245cmd_incomplete:
 246        freqs.new = freqs.old;
 247        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 248        iowrite16(0, &pcch_hdr->status);
 249        spin_unlock(&pcc_lock);
 250        return -EINVAL;
 251}
 252
 253static int pcc_get_offset(int cpu)
 254{
 255        acpi_status status;
 256        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 257        union acpi_object *pccp, *offset;
 258        struct pcc_cpu *pcc_cpu_data;
 259        struct acpi_processor *pr;
 260        int ret = 0;
 261
 262        pr = per_cpu(processors, cpu);
 263        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 264
 265        if (!pr)
 266                return -ENODEV;
 267
 268        status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
 269        if (ACPI_FAILURE(status))
 270                return -ENODEV;
 271
 272        pccp = buffer.pointer;
 273        if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
 274                ret = -ENODEV;
 275                goto out_free;
 276        };
 277
 278        offset = &(pccp->package.elements[0]);
 279        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 280                ret = -ENODEV;
 281                goto out_free;
 282        }
 283
 284        pcc_cpu_data->input_offset = offset->integer.value;
 285
 286        offset = &(pccp->package.elements[1]);
 287        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 288                ret = -ENODEV;
 289                goto out_free;
 290        }
 291
 292        pcc_cpu_data->output_offset = offset->integer.value;
 293
 294        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 295        memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);
 296
 297        pr_debug("pcc_get_offset: for CPU %d: pcc_cpu_data "
 298                "input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x\n",
 299                cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
 300out_free:
 301        kfree(buffer.pointer);
 302        return ret;
 303}
 304
 305static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
 306{
 307        acpi_status status;
 308        struct acpi_object_list input;
 309        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 310        union acpi_object in_params[4];
 311        union acpi_object *out_obj;
 312        u32 capabilities[2];
 313        u32 errors;
 314        u32 supported;
 315        int ret = 0;
 316
 317        input.count = 4;
 318        input.pointer = in_params;
 319        in_params[0].type               = ACPI_TYPE_BUFFER;
 320        in_params[0].buffer.length      = 16;
 321        in_params[0].buffer.pointer     = OSC_UUID;
 322        in_params[1].type               = ACPI_TYPE_INTEGER;
 323        in_params[1].integer.value      = 1;
 324        in_params[2].type               = ACPI_TYPE_INTEGER;
 325        in_params[2].integer.value      = 2;
 326        in_params[3].type               = ACPI_TYPE_BUFFER;
 327        in_params[3].buffer.length      = 8;
 328        in_params[3].buffer.pointer     = (u8 *)&capabilities;
 329
 330        capabilities[0] = OSC_QUERY_ENABLE;
 331        capabilities[1] = 0x1;
 332
 333        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 334        if (ACPI_FAILURE(status))
 335                return -ENODEV;
 336
 337        if (!output.length)
 338                return -ENODEV;
 339
 340        out_obj = output.pointer;
 341        if (out_obj->type != ACPI_TYPE_BUFFER) {
 342                ret = -ENODEV;
 343                goto out_free;
 344        }
 345
 346        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 347        if (errors) {
 348                ret = -ENODEV;
 349                goto out_free;
 350        }
 351
 352        supported = *((u32 *)(out_obj->buffer.pointer + 4));
 353        if (!(supported & 0x1)) {
 354                ret = -ENODEV;
 355                goto out_free;
 356        }
 357
 358        kfree(output.pointer);
 359        capabilities[0] = 0x0;
 360        capabilities[1] = 0x1;
 361
 362        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 363        if (ACPI_FAILURE(status))
 364                return -ENODEV;
 365
 366        if (!output.length)
 367                return -ENODEV;
 368
 369        out_obj = output.pointer;
 370        if (out_obj->type != ACPI_TYPE_BUFFER) {
 371                ret = -ENODEV;
 372                goto out_free;
 373        }
 374
 375        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 376        if (errors) {
 377                ret = -ENODEV;
 378                goto out_free;
 379        }
 380
 381        supported = *((u32 *)(out_obj->buffer.pointer + 4));
 382        if (!(supported & 0x1)) {
 383                ret = -ENODEV;
 384                goto out_free;
 385        }
 386
 387out_free:
 388        kfree(output.pointer);
 389        return ret;
 390}
 391
 392static int __init pcc_cpufreq_probe(void)
 393{
 394        acpi_status status;
 395        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 396        struct pcc_memory_resource *mem_resource;
 397        struct pcc_register_resource *reg_resource;
 398        union acpi_object *out_obj, *member;
 399        acpi_handle handle, osc_handle, pcch_handle;
 400        int ret = 0;
 401
 402        status = acpi_get_handle(NULL, "\\_SB", &handle);
 403        if (ACPI_FAILURE(status))
 404                return -ENODEV;
 405
 406        status = acpi_get_handle(handle, "PCCH", &pcch_handle);
 407        if (ACPI_FAILURE(status))
 408                return -ENODEV;
 409
 410        status = acpi_get_handle(handle, "_OSC", &osc_handle);
 411        if (ACPI_SUCCESS(status)) {
 412                ret = pcc_cpufreq_do_osc(&osc_handle);
 413                if (ret)
 414                        pr_debug("probe: _OSC evaluation did not succeed\n");
 415                /* Firmware's use of _OSC is optional */
 416                ret = 0;
 417        }
 418
 419        status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
 420        if (ACPI_FAILURE(status))
 421                return -ENODEV;
 422
 423        out_obj = output.pointer;
 424        if (out_obj->type != ACPI_TYPE_PACKAGE) {
 425                ret = -ENODEV;
 426                goto out_free;
 427        }
 428
 429        member = &out_obj->package.elements[0];
 430        if (member->type != ACPI_TYPE_BUFFER) {
 431                ret = -ENODEV;
 432                goto out_free;
 433        }
 434
 435        mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;
 436
 437        pr_debug("probe: mem_resource descriptor: 0x%x,"
 438                " length: %d, space_id: %d, resource_usage: %d,"
 439                " type_specific: %d, granularity: 0x%llx,"
 440                " minimum: 0x%llx, maximum: 0x%llx,"
 441                " translation_offset: 0x%llx, address_length: 0x%llx\n",
 442                mem_resource->descriptor, mem_resource->length,
 443                mem_resource->space_id, mem_resource->resource_usage,
 444                mem_resource->type_specific, mem_resource->granularity,
 445                mem_resource->minimum, mem_resource->maximum,
 446                mem_resource->translation_offset,
 447                mem_resource->address_length);
 448
 449        if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 450                ret = -ENODEV;
 451                goto out_free;
 452        }
 453
 454        pcch_virt_addr = ioremap_nocache(mem_resource->minimum,
 455                                        mem_resource->address_length);
 456        if (pcch_virt_addr == NULL) {
 457                pr_debug("probe: could not map shared mem region\n");
 458                ret = -ENOMEM;
 459                goto out_free;
 460        }
 461        pcch_hdr = pcch_virt_addr;
 462
 463        pr_debug("probe: PCCH header (virtual) addr: 0x%p\n", pcch_hdr);
 464        pr_debug("probe: PCCH header is at physical address: 0x%llx,"
 465                " signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
 466                " supported features: 0x%x, command field: 0x%x,"
 467                " status field: 0x%x, nominal latency: %d us\n",
 468                mem_resource->minimum, ioread32(&pcch_hdr->signature),
 469                ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
 470                ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
 471                ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
 472                ioread32(&pcch_hdr->latency));
 473
 474        pr_debug("probe: min time between commands: %d us,"
 475                " max time between commands: %d us,"
 476                " nominal CPU frequency: %d MHz,"
 477                " minimum CPU frequency: %d MHz,"
 478                " minimum CPU frequency without throttling: %d MHz\n",
 479                ioread32(&pcch_hdr->minimum_time),
 480                ioread32(&pcch_hdr->maximum_time),
 481                ioread32(&pcch_hdr->nominal),
 482                ioread32(&pcch_hdr->throttled_frequency),
 483                ioread32(&pcch_hdr->minimum_frequency));
 484
 485        member = &out_obj->package.elements[1];
 486        if (member->type != ACPI_TYPE_BUFFER) {
 487                ret = -ENODEV;
 488                goto pcch_free;
 489        }
 490
 491        reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
 492
 493        doorbell.space_id = reg_resource->space_id;
 494        doorbell.bit_width = reg_resource->bit_width;
 495        doorbell.bit_offset = reg_resource->bit_offset;
 496        doorbell.access_width = 64;
 497        doorbell.address = reg_resource->address;
 498
 499        pr_debug("probe: doorbell: space_id is %d, bit_width is %d, "
 500                "bit_offset is %d, access_width is %d, address is 0x%llx\n",
 501                doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
 502                doorbell.access_width, reg_resource->address);
 503
 504        member = &out_obj->package.elements[2];
 505        if (member->type != ACPI_TYPE_INTEGER) {
 506                ret = -ENODEV;
 507                goto pcch_free;
 508        }
 509
 510        doorbell_preserve = member->integer.value;
 511
 512        member = &out_obj->package.elements[3];
 513        if (member->type != ACPI_TYPE_INTEGER) {
 514                ret = -ENODEV;
 515                goto pcch_free;
 516        }
 517
 518        doorbell_write = member->integer.value;
 519
 520        pr_debug("probe: doorbell_preserve: 0x%llx,"
 521                " doorbell_write: 0x%llx\n",
 522                doorbell_preserve, doorbell_write);
 523
 524        pcc_cpu_info = alloc_percpu(struct pcc_cpu);
 525        if (!pcc_cpu_info) {
 526                ret = -ENOMEM;
 527                goto pcch_free;
 528        }
 529
 530        printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
 531               " limits: %d MHz, %d MHz\n", PCC_VERSION,
 532               ioread32(&pcch_hdr->minimum_frequency),
 533               ioread32(&pcch_hdr->nominal));
 534        kfree(output.pointer);
 535        return ret;
 536pcch_free:
 537        pcc_clear_mapping();
 538out_free:
 539        kfree(output.pointer);
 540        return ret;
 541}
 542
 543static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 544{
 545        unsigned int cpu = policy->cpu;
 546        unsigned int result = 0;
 547
 548        if (!pcch_virt_addr) {
 549                result = -1;
 550                goto out;
 551        }
 552
 553        result = pcc_get_offset(cpu);
 554        if (result) {
 555                pr_debug("init: PCCP evaluation failed\n");
 556                goto out;
 557        }
 558
 559        policy->max = policy->cpuinfo.max_freq =
 560                ioread32(&pcch_hdr->nominal) * 1000;
 561        policy->min = policy->cpuinfo.min_freq =
 562                ioread32(&pcch_hdr->minimum_frequency) * 1000;
 563        policy->cur = pcc_get_freq(cpu);
 564
 565        if (!policy->cur) {
 566                pr_debug("init: Unable to get current CPU frequency\n");
 567                result = -EINVAL;
 568                goto out;
 569        }
 570
 571        pr_debug("init: policy->max is %d, policy->min is %d\n",
 572                policy->max, policy->min);
 573out:
 574        return result;
 575}
 576
 577static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 578{
 579        return 0;
 580}
 581
 582static struct cpufreq_driver pcc_cpufreq_driver = {
 583        .flags = CPUFREQ_CONST_LOOPS,
 584        .get = pcc_get_freq,
 585        .verify = pcc_cpufreq_verify,
 586        .target = pcc_cpufreq_target,
 587        .init = pcc_cpufreq_cpu_init,
 588        .exit = pcc_cpufreq_cpu_exit,
 589        .name = "pcc-cpufreq",
 590        .owner = THIS_MODULE,
 591};
 592
 593static int __init pcc_cpufreq_init(void)
 594{
 595        int ret;
 596
 597        if (acpi_disabled)
 598                return 0;
 599
 600        ret = pcc_cpufreq_probe();
 601        if (ret) {
 602                pr_debug("pcc_cpufreq_init: PCCH evaluation failed\n");
 603                return ret;
 604        }
 605
 606        ret = cpufreq_register_driver(&pcc_cpufreq_driver);
 607
 608        return ret;
 609}
 610
 611static void __exit pcc_cpufreq_exit(void)
 612{
 613        cpufreq_unregister_driver(&pcc_cpufreq_driver);
 614
 615        pcc_clear_mapping();
 616
 617        free_percpu(pcc_cpu_info);
 618}
 619
 620MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
 621MODULE_VERSION(PCC_VERSION);
 622MODULE_DESCRIPTION("Processor Clocking Control interface driver");
 623MODULE_LICENSE("GPL");
 624
 625late_initcall(pcc_cpufreq_init);
 626module_exit(pcc_cpufreq_exit);
 627
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