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        freqs.cpu = cpu;
 219        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 220
 221        input_buffer = 0x1 | (((target_freq * 100)
 222                               / (ioread32(&pcch_hdr->nominal) * 1000)) << 8);
 223        iowrite32(input_buffer,
 224                        (pcch_virt_addr + pcc_cpu_data->input_offset));
 225        iowrite16(CMD_SET_FREQ, &pcch_hdr->command);
 226
 227        pcc_cmd();
 228
 229        /* Clear the input buffer - we are done with the current command */
 230        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 231
 232        status = ioread16(&pcch_hdr->status);
 233        if (status != CMD_COMPLETE) {
 234                pr_debug("target: FAILED for cpu %d, with status: 0x%x\n",
 235                        cpu, status);
 236                goto cmd_incomplete;
 237        }
 238        iowrite16(0, &pcch_hdr->status);
 239
 240        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 241        pr_debug("target: was SUCCESSFUL for cpu %d\n", cpu);
 242        spin_unlock(&pcc_lock);
 243
 244        return 0;
 245
 246cmd_incomplete:
 247        iowrite16(0, &pcch_hdr->status);
 248        spin_unlock(&pcc_lock);
 249        return -EINVAL;
 250}
 251
 252static int pcc_get_offset(int cpu)
 253{
 254        acpi_status status;
 255        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 256        union acpi_object *pccp, *offset;
 257        struct pcc_cpu *pcc_cpu_data;
 258        struct acpi_processor *pr;
 259        int ret = 0;
 260
 261        pr = per_cpu(processors, cpu);
 262        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 263
 264        if (!pr)
 265                return -ENODEV;
 266
 267        status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
 268        if (ACPI_FAILURE(status))
 269                return -ENODEV;
 270
 271        pccp = buffer.pointer;
 272        if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
 273                ret = -ENODEV;
 274                goto out_free;
 275        };
 276
 277        offset = &(pccp->package.elements[0]);
 278        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 279                ret = -ENODEV;
 280                goto out_free;
 281        }
 282
 283        pcc_cpu_data->input_offset = offset->integer.value;
 284
 285        offset = &(pccp->package.elements[1]);
 286        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 287                ret = -ENODEV;
 288                goto out_free;
 289        }
 290
 291        pcc_cpu_data->output_offset = offset->integer.value;
 292
 293        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 294        memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);
 295
 296        pr_debug("pcc_get_offset: for CPU %d: pcc_cpu_data "
 297                "input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x\n",
 298                cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
 299out_free:
 300        kfree(buffer.pointer);
 301        return ret;
 302}
 303
 304static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
 305{
 306        acpi_status status;
 307        struct acpi_object_list input;
 308        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 309        union acpi_object in_params[4];
 310        union acpi_object *out_obj;
 311        u32 capabilities[2];
 312        u32 errors;
 313        u32 supported;
 314        int ret = 0;
 315
 316        input.count = 4;
 317        input.pointer = in_params;
 318        in_params[0].type               = ACPI_TYPE_BUFFER;
 319        in_params[0].buffer.length      = 16;
 320        in_params[0].buffer.pointer     = OSC_UUID;
 321        in_params[1].type               = ACPI_TYPE_INTEGER;
 322        in_params[1].integer.value      = 1;
 323        in_params[2].type               = ACPI_TYPE_INTEGER;
 324        in_params[2].integer.value      = 2;
 325        in_params[3].type               = ACPI_TYPE_BUFFER;
 326        in_params[3].buffer.length      = 8;
 327        in_params[3].buffer.pointer     = (u8 *)&capabilities;
 328
 329        capabilities[0] = OSC_QUERY_ENABLE;
 330        capabilities[1] = 0x1;
 331
 332        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 333        if (ACPI_FAILURE(status))
 334                return -ENODEV;
 335
 336        if (!output.length)
 337                return -ENODEV;
 338
 339        out_obj = output.pointer;
 340        if (out_obj->type != ACPI_TYPE_BUFFER) {
 341                ret = -ENODEV;
 342                goto out_free;
 343        }
 344
 345        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 346        if (errors) {
 347                ret = -ENODEV;
 348                goto out_free;
 349        }
 350
 351        supported = *((u32 *)(out_obj->buffer.pointer + 4));
 352        if (!(supported & 0x1)) {
 353                ret = -ENODEV;
 354                goto out_free;
 355        }
 356
 357        kfree(output.pointer);
 358        capabilities[0] = 0x0;
 359        capabilities[1] = 0x1;
 360
 361        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 362        if (ACPI_FAILURE(status))
 363                return -ENODEV;
 364
 365        if (!output.length)
 366                return -ENODEV;
 367
 368        out_obj = output.pointer;
 369        if (out_obj->type != ACPI_TYPE_BUFFER) {
 370                ret = -ENODEV;
 371                goto out_free;
 372        }
 373
 374        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 375        if (errors) {
 376                ret = -ENODEV;
 377                goto out_free;
 378        }
 379
 380        supported = *((u32 *)(out_obj->buffer.pointer + 4));
 381        if (!(supported & 0x1)) {
 382                ret = -ENODEV;
 383                goto out_free;
 384        }
 385
 386out_free:
 387        kfree(output.pointer);
 388        return ret;
 389}
 390
 391static int __init pcc_cpufreq_probe(void)
 392{
 393        acpi_status status;
 394        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 395        struct pcc_memory_resource *mem_resource;
 396        struct pcc_register_resource *reg_resource;
 397        union acpi_object *out_obj, *member;
 398        acpi_handle handle, osc_handle, pcch_handle;
 399        int ret = 0;
 400
 401        status = acpi_get_handle(NULL, "\\_SB", &handle);
 402        if (ACPI_FAILURE(status))
 403                return -ENODEV;
 404
 405        status = acpi_get_handle(handle, "PCCH", &pcch_handle);
 406        if (ACPI_FAILURE(status))
 407                return -ENODEV;
 408
 409        status = acpi_get_handle(handle, "_OSC", &osc_handle);
 410        if (ACPI_SUCCESS(status)) {
 411                ret = pcc_cpufreq_do_osc(&osc_handle);
 412                if (ret)
 413                        pr_debug("probe: _OSC evaluation did not succeed\n");
 414                /* Firmware's use of _OSC is optional */
 415                ret = 0;
 416        }
 417
 418        status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
 419        if (ACPI_FAILURE(status))
 420                return -ENODEV;
 421
 422        out_obj = output.pointer;
 423        if (out_obj->type != ACPI_TYPE_PACKAGE) {
 424                ret = -ENODEV;
 425                goto out_free;
 426        }
 427
 428        member = &out_obj->package.elements[0];
 429        if (member->type != ACPI_TYPE_BUFFER) {
 430                ret = -ENODEV;
 431                goto out_free;
 432        }
 433
 434        mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;
 435
 436        pr_debug("probe: mem_resource descriptor: 0x%x,"
 437                " length: %d, space_id: %d, resource_usage: %d,"
 438                " type_specific: %d, granularity: 0x%llx,"
 439                " minimum: 0x%llx, maximum: 0x%llx,"
 440                " translation_offset: 0x%llx, address_length: 0x%llx\n",
 441                mem_resource->descriptor, mem_resource->length,
 442                mem_resource->space_id, mem_resource->resource_usage,
 443                mem_resource->type_specific, mem_resource->granularity,
 444                mem_resource->minimum, mem_resource->maximum,
 445                mem_resource->translation_offset,
 446                mem_resource->address_length);
 447
 448        if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 449                ret = -ENODEV;
 450                goto out_free;
 451        }
 452
 453        pcch_virt_addr = ioremap_nocache(mem_resource->minimum,
 454                                        mem_resource->address_length);
 455        if (pcch_virt_addr == NULL) {
 456                pr_debug("probe: could not map shared mem region\n");
 457                ret = -ENOMEM;
 458                goto out_free;
 459        }
 460        pcch_hdr = pcch_virt_addr;
 461
 462        pr_debug("probe: PCCH header (virtual) addr: 0x%p\n", pcch_hdr);
 463        pr_debug("probe: PCCH header is at physical address: 0x%llx,"
 464                " signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
 465                " supported features: 0x%x, command field: 0x%x,"
 466                " status field: 0x%x, nominal latency: %d us\n",
 467                mem_resource->minimum, ioread32(&pcch_hdr->signature),
 468                ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
 469                ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
 470                ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
 471                ioread32(&pcch_hdr->latency));
 472
 473        pr_debug("probe: min time between commands: %d us,"
 474                " max time between commands: %d us,"
 475                " nominal CPU frequency: %d MHz,"
 476                " minimum CPU frequency: %d MHz,"
 477                " minimum CPU frequency without throttling: %d MHz\n",
 478                ioread32(&pcch_hdr->minimum_time),
 479                ioread32(&pcch_hdr->maximum_time),
 480                ioread32(&pcch_hdr->nominal),
 481                ioread32(&pcch_hdr->throttled_frequency),
 482                ioread32(&pcch_hdr->minimum_frequency));
 483
 484        member = &out_obj->package.elements[1];
 485        if (member->type != ACPI_TYPE_BUFFER) {
 486                ret = -ENODEV;
 487                goto pcch_free;
 488        }
 489
 490        reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
 491
 492        doorbell.space_id = reg_resource->space_id;
 493        doorbell.bit_width = reg_resource->bit_width;
 494        doorbell.bit_offset = reg_resource->bit_offset;
 495        doorbell.access_width = 64;
 496        doorbell.address = reg_resource->address;
 497
 498        pr_debug("probe: doorbell: space_id is %d, bit_width is %d, "
 499                "bit_offset is %d, access_width is %d, address is 0x%llx\n",
 500                doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
 501                doorbell.access_width, reg_resource->address);
 502
 503        member = &out_obj->package.elements[2];
 504        if (member->type != ACPI_TYPE_INTEGER) {
 505                ret = -ENODEV;
 506                goto pcch_free;
 507        }
 508
 509        doorbell_preserve = member->integer.value;
 510
 511        member = &out_obj->package.elements[3];
 512        if (member->type != ACPI_TYPE_INTEGER) {
 513                ret = -ENODEV;
 514                goto pcch_free;
 515        }
 516
 517        doorbell_write = member->integer.value;
 518
 519        pr_debug("probe: doorbell_preserve: 0x%llx,"
 520                " doorbell_write: 0x%llx\n",
 521                doorbell_preserve, doorbell_write);
 522
 523        pcc_cpu_info = alloc_percpu(struct pcc_cpu);
 524        if (!pcc_cpu_info) {
 525                ret = -ENOMEM;
 526                goto pcch_free;
 527        }
 528
 529        printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
 530               " limits: %d MHz, %d MHz\n", PCC_VERSION,
 531               ioread32(&pcch_hdr->minimum_frequency),
 532               ioread32(&pcch_hdr->nominal));
 533        kfree(output.pointer);
 534        return ret;
 535pcch_free:
 536        pcc_clear_mapping();
 537out_free:
 538        kfree(output.pointer);
 539        return ret;
 540}
 541
 542static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 543{
 544        unsigned int cpu = policy->cpu;
 545        unsigned int result = 0;
 546
 547        if (!pcch_virt_addr) {
 548                result = -1;
 549                goto out;
 550        }
 551
 552        result = pcc_get_offset(cpu);
 553        if (result) {
 554                pr_debug("init: PCCP evaluation failed\n");
 555                goto out;
 556        }
 557
 558        policy->max = policy->cpuinfo.max_freq =
 559                ioread32(&pcch_hdr->nominal) * 1000;
 560        policy->min = policy->cpuinfo.min_freq =
 561                ioread32(&pcch_hdr->minimum_frequency) * 1000;
 562        policy->cur = pcc_get_freq(cpu);
 563
 564        if (!policy->cur) {
 565                pr_debug("init: Unable to get current CPU frequency\n");
 566                result = -EINVAL;
 567                goto out;
 568        }
 569
 570        pr_debug("init: policy->max is %d, policy->min is %d\n",
 571                policy->max, policy->min);
 572out:
 573        return result;
 574}
 575
 576static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 577{
 578        return 0;
 579}
 580
 581static struct cpufreq_driver pcc_cpufreq_driver = {
 582        .flags = CPUFREQ_CONST_LOOPS,
 583        .get = pcc_get_freq,
 584        .verify = pcc_cpufreq_verify,
 585        .target = pcc_cpufreq_target,
 586        .init = pcc_cpufreq_cpu_init,
 587        .exit = pcc_cpufreq_cpu_exit,
 588        .name = "pcc-cpufreq",
 589        .owner = THIS_MODULE,
 590};
 591
 592static int __init pcc_cpufreq_init(void)
 593{
 594        int ret;
 595
 596        if (acpi_disabled)
 597                return 0;
 598
 599        ret = pcc_cpufreq_probe();
 600        if (ret) {
 601                pr_debug("pcc_cpufreq_init: PCCH evaluation failed\n");
 602                return ret;
 603        }
 604
 605        ret = cpufreq_register_driver(&pcc_cpufreq_driver);
 606
 607        return ret;
 608}
 609
 610static void __exit pcc_cpufreq_exit(void)
 611{
 612        cpufreq_unregister_driver(&pcc_cpufreq_driver);
 613
 614        pcc_clear_mapping();
 615
 616        free_percpu(pcc_cpu_info);
 617}
 618
 619MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
 620MODULE_VERSION(PCC_VERSION);
 621MODULE_DESCRIPTION("Processor Clocking Control interface driver");
 622MODULE_LICENSE("GPL");
 623
 624late_initcall(pcc_cpufreq_init);
 625module_exit(pcc_cpufreq_exit);
 626
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