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        iowrite16(0, &pcch_hdr->status);
 247        spin_unlock(&pcc_lock);
 248        return -EINVAL;
 249}
 250
 251static int pcc_get_offset(int cpu)
 252{
 253        acpi_status status;
 254        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 255        union acpi_object *pccp, *offset;
 256        struct pcc_cpu *pcc_cpu_data;
 257        struct acpi_processor *pr;
 258        int ret = 0;
 259
 260        pr = per_cpu(processors, cpu);
 261        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 262
 263        if (!pr)
 264                return -ENODEV;
 265
 266        status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
 267        if (ACPI_FAILURE(status))
 268                return -ENODEV;
 269
 270        pccp = buffer.pointer;
 271        if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
 272                ret = -ENODEV;
 273                goto out_free;
 274        };
 275
 276        offset = &(pccp->package.elements[0]);
 277        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 278                ret = -ENODEV;
 279                goto out_free;
 280        }
 281
 282        pcc_cpu_data->input_offset = offset->integer.value;
 283
 284        offset = &(pccp->package.elements[1]);
 285        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 286                ret = -ENODEV;
 287                goto out_free;
 288        }
 289
 290        pcc_cpu_data->output_offset = offset->integer.value;
 291
 292        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 293        memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);
 294
 295        pr_debug("pcc_get_offset: for CPU %d: pcc_cpu_data "
 296                "input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x\n",
 297                cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
 298out_free:
 299        kfree(buffer.pointer);
 300        return ret;
 301}
 302
 303static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
 304{
 305        acpi_status status;
 306        struct acpi_object_list input;
 307        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 308        union acpi_object in_params[4];
 309        union acpi_object *out_obj;
 310        u32 capabilities[2];
 311        u32 errors;
 312        u32 supported;
 313        int ret = 0;
 314
 315        input.count = 4;
 316        input.pointer = in_params;
 317        in_params[0].type               = ACPI_TYPE_BUFFER;
 318        in_params[0].buffer.length      = 16;
 319        in_params[0].buffer.pointer     = OSC_UUID;
 320        in_params[1].type               = ACPI_TYPE_INTEGER;
 321        in_params[1].integer.value      = 1;
 322        in_params[2].type               = ACPI_TYPE_INTEGER;
 323        in_params[2].integer.value      = 2;
 324        in_params[3].type               = ACPI_TYPE_BUFFER;
 325        in_params[3].buffer.length      = 8;
 326        in_params[3].buffer.pointer     = (u8 *)&capabilities;
 327
 328        capabilities[0] = OSC_QUERY_ENABLE;
 329        capabilities[1] = 0x1;
 330
 331        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 332        if (ACPI_FAILURE(status))
 333                return -ENODEV;
 334
 335        if (!output.length)
 336                return -ENODEV;
 337
 338        out_obj = output.pointer;
 339        if (out_obj->type != ACPI_TYPE_BUFFER) {
 340                ret = -ENODEV;
 341                goto out_free;
 342        }
 343
 344        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 345        if (errors) {
 346                ret = -ENODEV;
 347                goto out_free;
 348        }
 349
 350        supported = *((u32 *)(out_obj->buffer.pointer + 4));
 351        if (!(supported & 0x1)) {
 352                ret = -ENODEV;
 353                goto out_free;
 354        }
 355
 356        kfree(output.pointer);
 357        capabilities[0] = 0x0;
 358        capabilities[1] = 0x1;
 359
 360        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 361        if (ACPI_FAILURE(status))
 362                return -ENODEV;
 363
 364        if (!output.length)
 365                return -ENODEV;
 366
 367        out_obj = output.pointer;
 368        if (out_obj->type != ACPI_TYPE_BUFFER) {
 369                ret = -ENODEV;
 370                goto out_free;
 371        }
 372
 373        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 374        if (errors) {
 375                ret = -ENODEV;
 376                goto out_free;
 377        }
 378
 379        supported = *((u32 *)(out_obj->buffer.pointer + 4));
 380        if (!(supported & 0x1)) {
 381                ret = -ENODEV;
 382                goto out_free;
 383        }
 384
 385out_free:
 386        kfree(output.pointer);
 387        return ret;
 388}
 389
 390static int __init pcc_cpufreq_probe(void)
 391{
 392        acpi_status status;
 393        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 394        struct pcc_memory_resource *mem_resource;
 395        struct pcc_register_resource *reg_resource;
 396        union acpi_object *out_obj, *member;
 397        acpi_handle handle, osc_handle, pcch_handle;
 398        int ret = 0;
 399
 400        status = acpi_get_handle(NULL, "\\_SB", &handle);
 401        if (ACPI_FAILURE(status))
 402                return -ENODEV;
 403
 404        status = acpi_get_handle(handle, "PCCH", &pcch_handle);
 405        if (ACPI_FAILURE(status))
 406                return -ENODEV;
 407
 408        status = acpi_get_handle(handle, "_OSC", &osc_handle);
 409        if (ACPI_SUCCESS(status)) {
 410                ret = pcc_cpufreq_do_osc(&osc_handle);
 411                if (ret)
 412                        pr_debug("probe: _OSC evaluation did not succeed\n");
 413                /* Firmware's use of _OSC is optional */
 414                ret = 0;
 415        }
 416
 417        status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
 418        if (ACPI_FAILURE(status))
 419                return -ENODEV;
 420
 421        out_obj = output.pointer;
 422        if (out_obj->type != ACPI_TYPE_PACKAGE) {
 423                ret = -ENODEV;
 424                goto out_free;
 425        }
 426
 427        member = &out_obj->package.elements[0];
 428        if (member->type != ACPI_TYPE_BUFFER) {
 429                ret = -ENODEV;
 430                goto out_free;
 431        }
 432
 433        mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;
 434
 435        pr_debug("probe: mem_resource descriptor: 0x%x,"
 436                " length: %d, space_id: %d, resource_usage: %d,"
 437                " type_specific: %d, granularity: 0x%llx,"
 438                " minimum: 0x%llx, maximum: 0x%llx,"
 439                " translation_offset: 0x%llx, address_length: 0x%llx\n",
 440                mem_resource->descriptor, mem_resource->length,
 441                mem_resource->space_id, mem_resource->resource_usage,
 442                mem_resource->type_specific, mem_resource->granularity,
 443                mem_resource->minimum, mem_resource->maximum,
 444                mem_resource->translation_offset,
 445                mem_resource->address_length);
 446
 447        if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 448                ret = -ENODEV;
 449                goto out_free;
 450        }
 451
 452        pcch_virt_addr = ioremap_nocache(mem_resource->minimum,
 453                                        mem_resource->address_length);
 454        if (pcch_virt_addr == NULL) {
 455                pr_debug("probe: could not map shared mem region\n");
 456                ret = -ENOMEM;
 457                goto out_free;
 458        }
 459        pcch_hdr = pcch_virt_addr;
 460
 461        pr_debug("probe: PCCH header (virtual) addr: 0x%p\n", pcch_hdr);
 462        pr_debug("probe: PCCH header is at physical address: 0x%llx,"
 463                " signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
 464                " supported features: 0x%x, command field: 0x%x,"
 465                " status field: 0x%x, nominal latency: %d us\n",
 466                mem_resource->minimum, ioread32(&pcch_hdr->signature),
 467                ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
 468                ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
 469                ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
 470                ioread32(&pcch_hdr->latency));
 471
 472        pr_debug("probe: min time between commands: %d us,"
 473                " max time between commands: %d us,"
 474                " nominal CPU frequency: %d MHz,"
 475                " minimum CPU frequency: %d MHz,"
 476                " minimum CPU frequency without throttling: %d MHz\n",
 477                ioread32(&pcch_hdr->minimum_time),
 478                ioread32(&pcch_hdr->maximum_time),
 479                ioread32(&pcch_hdr->nominal),
 480                ioread32(&pcch_hdr->throttled_frequency),
 481                ioread32(&pcch_hdr->minimum_frequency));
 482
 483        member = &out_obj->package.elements[1];
 484        if (member->type != ACPI_TYPE_BUFFER) {
 485                ret = -ENODEV;
 486                goto pcch_free;
 487        }
 488
 489        reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
 490
 491        doorbell.space_id = reg_resource->space_id;
 492        doorbell.bit_width = reg_resource->bit_width;
 493        doorbell.bit_offset = reg_resource->bit_offset;
 494        doorbell.access_width = 64;
 495        doorbell.address = reg_resource->address;
 496
 497        pr_debug("probe: doorbell: space_id is %d, bit_width is %d, "
 498                "bit_offset is %d, access_width is %d, address is 0x%llx\n",
 499                doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
 500                doorbell.access_width, reg_resource->address);
 501
 502        member = &out_obj->package.elements[2];
 503        if (member->type != ACPI_TYPE_INTEGER) {
 504                ret = -ENODEV;
 505                goto pcch_free;
 506        }
 507
 508        doorbell_preserve = member->integer.value;
 509
 510        member = &out_obj->package.elements[3];
 511        if (member->type != ACPI_TYPE_INTEGER) {
 512                ret = -ENODEV;
 513                goto pcch_free;
 514        }
 515
 516        doorbell_write = member->integer.value;
 517
 518        pr_debug("probe: doorbell_preserve: 0x%llx,"
 519                " doorbell_write: 0x%llx\n",
 520                doorbell_preserve, doorbell_write);
 521
 522        pcc_cpu_info = alloc_percpu(struct pcc_cpu);
 523        if (!pcc_cpu_info) {
 524                ret = -ENOMEM;
 525                goto pcch_free;
 526        }
 527
 528        printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
 529               " limits: %d MHz, %d MHz\n", PCC_VERSION,
 530               ioread32(&pcch_hdr->minimum_frequency),
 531               ioread32(&pcch_hdr->nominal));
 532        kfree(output.pointer);
 533        return ret;
 534pcch_free:
 535        pcc_clear_mapping();
 536out_free:
 537        kfree(output.pointer);
 538        return ret;
 539}
 540
 541static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 542{
 543        unsigned int cpu = policy->cpu;
 544        unsigned int result = 0;
 545
 546        if (!pcch_virt_addr) {
 547                result = -1;
 548                goto out;
 549        }
 550
 551        result = pcc_get_offset(cpu);
 552        if (result) {
 553                pr_debug("init: PCCP evaluation failed\n");
 554                goto out;
 555        }
 556
 557        policy->max = policy->cpuinfo.max_freq =
 558                ioread32(&pcch_hdr->nominal) * 1000;
 559        policy->min = policy->cpuinfo.min_freq =
 560                ioread32(&pcch_hdr->minimum_frequency) * 1000;
 561        policy->cur = pcc_get_freq(cpu);
 562
 563        if (!policy->cur) {
 564                pr_debug("init: Unable to get current CPU frequency\n");
 565                result = -EINVAL;
 566                goto out;
 567        }
 568
 569        pr_debug("init: policy->max is %d, policy->min is %d\n",
 570                policy->max, policy->min);
 571out:
 572        return result;
 573}
 574
 575static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 576{
 577        return 0;
 578}
 579
 580static struct cpufreq_driver pcc_cpufreq_driver = {
 581        .flags = CPUFREQ_CONST_LOOPS,
 582        .get = pcc_get_freq,
 583        .verify = pcc_cpufreq_verify,
 584        .target = pcc_cpufreq_target,
 585        .init = pcc_cpufreq_cpu_init,
 586        .exit = pcc_cpufreq_cpu_exit,
 587        .name = "pcc-cpufreq",
 588        .owner = THIS_MODULE,
 589};
 590
 591static int __init pcc_cpufreq_init(void)
 592{
 593        int ret;
 594
 595        if (acpi_disabled)
 596                return 0;
 597
 598        ret = pcc_cpufreq_probe();
 599        if (ret) {
 600                pr_debug("pcc_cpufreq_init: PCCH evaluation failed\n");
 601                return ret;
 602        }
 603
 604        ret = cpufreq_register_driver(&pcc_cpufreq_driver);
 605
 606        return ret;
 607}
 608
 609static void __exit pcc_cpufreq_exit(void)
 610{
 611        cpufreq_unregister_driver(&pcc_cpufreq_driver);
 612
 613        pcc_clear_mapping();
 614
 615        free_percpu(pcc_cpu_info);
 616}
 617
 618MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
 619MODULE_VERSION(PCC_VERSION);
 620MODULE_DESCRIPTION("Processor Clocking Control interface driver");
 621MODULE_LICENSE("GPL");
 622
 623late_initcall(pcc_cpufreq_init);
 624module_exit(pcc_cpufreq_exit);
 625
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