drivers/acpi/cppc_acpi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * CPPC (Collaborative Processor Performance Control) methods used by CPUfreq drivers.
   4  *
   5  * (C) Copyright 2014, 2015 Linaro Ltd.
   6  * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
   7  *
   8  * CPPC describes a few methods for controlling CPU performance using
   9  * information from a per CPU table called CPC. This table is described in
  10  * the ACPI v5.0+ specification. The table consists of a list of
  11  * registers which may be memory mapped or hardware registers and also may
  12  * include some static integer values.
  13  *
  14  * CPU performance is on an abstract continuous scale as against a discretized
  15  * P-state scale which is tied to CPU frequency only. In brief, the basic
  16  * operation involves:
  17  *
  18  * - OS makes a CPU performance request. (Can provide min and max bounds)
  19  *
  20  * - Platform (such as BMC) is free to optimize request within requested bounds
  21  *   depending on power/thermal budgets etc.
  22  *
  23  * - Platform conveys its decision back to OS
  24  *
  25  * The communication between OS and platform occurs through another medium
  26  * called (PCC) Platform Communication Channel. This is a generic mailbox like
  27  * mechanism which includes doorbell semantics to indicate register updates.
  28  * See drivers/mailbox/pcc.c for details on PCC.
  29  *
  30  * Finer details about the PCC and CPPC spec are available in the ACPI v5.1 and
  31  * above specifications.
  32  */
  33
  34 #define pr_fmt(fmt)     "ACPI CPPC: " fmt
  35
  36 #include <linux/cpufreq.h>
  37 #include <linux/delay.h>
  38 #include <linux/iopoll.h>
  39 #include <linux/ktime.h>
  40 #include <linux/rwsem.h>
  41 #include <linux/wait.h>
  42
  43 #include <acpi/cppc_acpi.h>
  44
  45 struct cppc_pcc_data {
  46         struct mbox_chan *pcc_channel;
  47         void __iomem *pcc_comm_addr;
  48         bool pcc_channel_acquired;
  49         unsigned int deadline_us;
  50         unsigned int pcc_mpar, pcc_mrtt, pcc_nominal;
  51
  52         bool pending_pcc_write_cmd;     /* Any pending/batched PCC write cmds? */
  53         bool platform_owns_pcc;         /* Ownership of PCC subspace */
  54         unsigned int pcc_write_cnt;     /* Running count of PCC write commands */
  55
  56         /*
  57          * Lock to provide controlled access to the PCC channel.
  58          *
  59          * For performance critical usecases(currently cppc_set_perf)
  60          *      We need to take read_lock and check if channel belongs to OSPM
  61          * before reading or writing to PCC subspace
  62          *      We need to take write_lock before transferring the channel
  63          * ownership to the platform via a Doorbell
  64          *      This allows us to batch a number of CPPC requests if they happen
  65          * to originate in about the same time
  66          *
  67          * For non-performance critical usecases(init)
  68          *      Take write_lock for all purposes which gives exclusive access
  69          */
  70         struct rw_semaphore pcc_lock;
  71
  72         /* Wait queue for CPUs whose requests were batched */
  73         wait_queue_head_t pcc_write_wait_q;
  74         ktime_t last_cmd_cmpl_time;
  75         ktime_t last_mpar_reset;
  76         int mpar_count;
  77         int refcount;
  78 };
  79
  80 /* Array to represent the PCC channel per subspace ID */
  81 static struct cppc_pcc_data *pcc_data[MAX_PCC_SUBSPACES];
  82 /* The cpu_pcc_subspace_idx contains per CPU subspace ID */
  83 static DEFINE_PER_CPU(int, cpu_pcc_subspace_idx);
  84
  85 /*
  86  * The cpc_desc structure contains the ACPI register details
  87  * as described in the per CPU _CPC tables. The details
  88  * include the type of register (e.g. PCC, System IO, FFH etc.)
  89  * and destination addresses which lets us READ/WRITE CPU performance
  90  * information using the appropriate I/O methods.
  91  */
  92 static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
  93
  94 /* pcc mapped address + header size + offset within PCC subspace */
  95 #define GET_PCC_VADDR(offs, pcc_ss_id) (pcc_data[pcc_ss_id]->pcc_comm_addr + \
  96                                                 0x8 + (offs))
  97
  98 /* Check if a CPC register is in PCC */
  99 #define CPC_IN_PCC(cpc) ((cpc)->type == ACPI_TYPE_BUFFER &&             \
 100                                 (cpc)->cpc_entry.reg.space_id ==        \
 101                                 ACPI_ADR_SPACE_PLATFORM_COMM)
 102
 103 /* Evalutes to True if reg is a NULL register descriptor */
 104 #define IS_NULL_REG(reg) ((reg)->space_id ==  ACPI_ADR_SPACE_SYSTEM_MEMORY && \
 105                                 (reg)->address == 0 &&                  \
 106                                 (reg)->bit_width == 0 &&                \
 107                                 (reg)->bit_offset == 0 &&               \
 108                                 (reg)->access_width == 0)
 109
 110 /* Evalutes to True if an optional cpc field is supported */
 111 #define CPC_SUPPORTED(cpc) ((cpc)->type == ACPI_TYPE_INTEGER ?          \
 112                                 !!(cpc)->cpc_entry.int_value :          \
 113                                 !IS_NULL_REG(&(cpc)->cpc_entry.reg))
 114 /*
 115  * Arbitrary Retries in case the remote processor is slow to respond
 116  * to PCC commands. Keeping it high enough to cover emulators where
 117  * the processors run painfully slow.
 118  */
 119 #define NUM_RETRIES 500ULL
 120
 121 struct cppc_attr {
 122         struct attribute attr;
 123         ssize_t (*show)(struct kobject *kobj,
 124                         struct attribute *attr, char *buf);
 125         ssize_t (*store)(struct kobject *kobj,
 126                         struct attribute *attr, const char *c, ssize_t count);
 127 };
 128
 129 #define define_one_cppc_ro(_name)               \
 130 static struct cppc_attr _name =                 \
 131 __ATTR(_name, 0444, show_##_name, NULL)
 132
 133 #define to_cpc_desc(a) container_of(a, struct cpc_desc, kobj)
 134
 135 #define show_cppc_data(access_fn, struct_name, member_name)             \
 136         static ssize_t show_##member_name(struct kobject *kobj,         \
 137                                         struct attribute *attr, char *buf) \
 138         {                                                               \
 139                 struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);           \
 140                 struct struct_name st_name = {0};                       \
 141                 int ret;                                                \
 142                                                                         \
 143                 ret = access_fn(cpc_ptr->cpu_id, &st_name);             \
 144                 if (ret)                                                \
 145                         return ret;                                     \
 146                                                                         \
 147                 return scnprintf(buf, PAGE_SIZE, "%llu\n",              \
 148                                 (u64)st_name.member_name);              \
 149         }                                                               \
 150         define_one_cppc_ro(member_name)
 151
 152 show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, highest_perf);
 153 show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_perf);
 154 show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_perf);
 155 show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_nonlinear_perf);
 156 show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_freq);
 157 show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_freq);
 158
 159 show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, reference_perf);
 160 show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time);
 161
 162 static ssize_t show_feedback_ctrs(struct kobject *kobj,
 163                 struct attribute *attr, char *buf)
 164 {
 165         struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);
 166         struct cppc_perf_fb_ctrs fb_ctrs = {0};
 167         int ret;
 168
 169         ret = cppc_get_perf_ctrs(cpc_ptr->cpu_id, &fb_ctrs);
 170         if (ret)
 171                 return ret;
 172
 173         return scnprintf(buf, PAGE_SIZE, "ref:%llu del:%llu\n",
 174                         fb_ctrs.reference, fb_ctrs.delivered);
 175 }
 176 define_one_cppc_ro(feedback_ctrs);
 177
 178 static struct attribute *cppc_attrs[] = {
 179         &feedback_ctrs.attr,
 180         &reference_perf.attr,
 181         &wraparound_time.attr,
 182         &highest_perf.attr,
 183         &lowest_perf.attr,
 184         &lowest_nonlinear_perf.attr,
 185         &nominal_perf.attr,
 186         &nominal_freq.attr,
 187         &lowest_freq.attr,
 188         NULL
 189 };
 190
 191 static struct kobj_type cppc_ktype = {
 192         .sysfs_ops = &kobj_sysfs_ops,
 193         .default_attrs = cppc_attrs,
 194 };
 195
 196 static int check_pcc_chan(int pcc_ss_id, bool chk_err_bit)
 197 {
 198         int ret, status;
 199         struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
 200         struct acpi_pcct_shared_memory __iomem *generic_comm_base =
 201                 pcc_ss_data->pcc_comm_addr;
 202
 203         if (!pcc_ss_data->platform_owns_pcc)
 204                 return 0;
 205
 206         /*
 207          * Poll PCC status register every 3us(delay_us) for maximum of
 208          * deadline_us(timeout_us) until PCC command complete bit is set(cond)
 209          */
 210         ret = readw_relaxed_poll_timeout(&generic_comm_base->status, status,
 211                                         status & PCC_CMD_COMPLETE_MASK, 3,
 212                                         pcc_ss_data->deadline_us);
 213
 214         if (likely(!ret)) {
 215                 pcc_ss_data->platform_owns_pcc = false;
 216                 if (chk_err_bit && (status & PCC_ERROR_MASK))
 217                         ret = -EIO;
 218         }
 219
 220         if (unlikely(ret))
 221                 pr_err("PCC check channel failed for ss: %d. ret=%d\n",
 222                        pcc_ss_id, ret);
 223
 224         return ret;
 225 }
 226
 227 /*
 228  * This function transfers the ownership of the PCC to the platform
 229  * So it must be called while holding write_lock(pcc_lock)
 230  */
 231 static int send_pcc_cmd(int pcc_ss_id, u16 cmd)
 232 {
 233         int ret = -EIO, i;
 234         struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
 235         struct acpi_pcct_shared_memory *generic_comm_base =
 236                 (struct acpi_pcct_shared_memory *)pcc_ss_data->pcc_comm_addr;
 237         unsigned int time_delta;
 238
 239         /*
 240          * For CMD_WRITE we know for a fact the caller should have checked
 241          * the channel before writing to PCC space
 242          */
 243         if (cmd == CMD_READ) {
 244                 /*
 245                  * If there are pending cpc_writes, then we stole the channel
 246                  * before write completion, so first send a WRITE command to
 247                  * platform
 248                  */
 249                 if (pcc_ss_data->pending_pcc_write_cmd)
 250                         send_pcc_cmd(pcc_ss_id, CMD_WRITE);
 251
 252                 ret = check_pcc_chan(pcc_ss_id, false);
 253                 if (ret)
 254                         goto end;
 255         } else /* CMD_WRITE */
 256                 pcc_ss_data->pending_pcc_write_cmd = FALSE;
 257
 258         /*
 259          * Handle the Minimum Request Turnaround Time(MRTT)
 260          * "The minimum amount of time that OSPM must wait after the completion
 261          * of a command before issuing the next command, in microseconds"
 262          */
 263         if (pcc_ss_data->pcc_mrtt) {
 264                 time_delta = ktime_us_delta(ktime_get(),
 265                                             pcc_ss_data->last_cmd_cmpl_time);
 266                 if (pcc_ss_data->pcc_mrtt > time_delta)
 267                         udelay(pcc_ss_data->pcc_mrtt - time_delta);
 268         }
 269
 270         /*
 271          * Handle the non-zero Maximum Periodic Access Rate(MPAR)
 272          * "The maximum number of periodic requests that the subspace channel can
 273          * support, reported in commands per minute. 0 indicates no limitation."
 274          *
 275          * This parameter should be ideally zero or large enough so that it can
 276          * handle maximum number of requests that all the cores in the system can
 277          * collectively generate. If it is not, we will follow the spec and just
 278          * not send the request to the platform after hitting the MPAR limit in
 279          * any 60s window
 280          */
 281         if (pcc_ss_data->pcc_mpar) {
 282                 if (pcc_ss_data->mpar_count == 0) {
 283                         time_delta = ktime_ms_delta(ktime_get(),
 284                                                     pcc_ss_data->last_mpar_reset);
 285                         if ((time_delta < 60 * MSEC_PER_SEC) && pcc_ss_data->last_mpar_reset) {
 286                                 pr_debug("PCC cmd for subspace %d not sent due to MPAR limit",
 287                                          pcc_ss_id);
 288                                 ret = -EIO;
 289                                 goto end;
 290                         }
 291                         pcc_ss_data->last_mpar_reset = ktime_get();
 292                         pcc_ss_data->mpar_count = pcc_ss_data->pcc_mpar;
 293                 }
 294                 pcc_ss_data->mpar_count--;
 295         }
 296
 297         /* Write to the shared comm region. */
 298         writew_relaxed(cmd, &generic_comm_base->command);
 299
 300         /* Flip CMD COMPLETE bit */
 301         writew_relaxed(0, &generic_comm_base->status);
 302
 303         pcc_ss_data->platform_owns_pcc = true;
 304
 305         /* Ring doorbell */
 306         ret = mbox_send_message(pcc_ss_data->pcc_channel, &cmd);
 307         if (ret < 0) {
 308                 pr_err("Err sending PCC mbox message. ss: %d cmd:%d, ret:%d\n",
 309                        pcc_ss_id, cmd, ret);
 310                 goto end;
 311         }
 312
 313         /* wait for completion and check for PCC errro bit */
 314         ret = check_pcc_chan(pcc_ss_id, true);
 315
 316         if (pcc_ss_data->pcc_mrtt)
 317                 pcc_ss_data->last_cmd_cmpl_time = ktime_get();
 318
 319         if (pcc_ss_data->pcc_channel->mbox->txdone_irq)
 320                 mbox_chan_txdone(pcc_ss_data->pcc_channel, ret);
 321         else
 322                 mbox_client_txdone(pcc_ss_data->pcc_channel, ret);
 323
 324 end:
 325         if (cmd == CMD_WRITE) {
 326                 if (unlikely(ret)) {
 327                         for_each_possible_cpu(i) {
 328                                 struct cpc_desc *desc = per_cpu(cpc_desc_ptr, i);
 329                                 if (!desc)
 330                                         continue;
 331
 332                                 if (desc->write_cmd_id == pcc_ss_data->pcc_write_cnt)
 333                                         desc->write_cmd_status = ret;
 334                         }
 335                 }
 336                 pcc_ss_data->pcc_write_cnt++;
 337                 wake_up_all(&pcc_ss_data->pcc_write_wait_q);
 338         }
 339
 340         return ret;
 341 }
 342
 343 static void cppc_chan_tx_done(struct mbox_client *cl, void *msg, int ret)
 344 {
 345         if (ret < 0)
 346                 pr_debug("TX did not complete: CMD sent:%x, ret:%d\n",
 347                                 *(u16 *)msg, ret);
 348         else
 349                 pr_debug("TX completed. CMD sent:%x, ret:%d\n",
 350                                 *(u16 *)msg, ret);
 351 }
 352
 353 struct mbox_client cppc_mbox_cl = {
 354         .tx_done = cppc_chan_tx_done,
 355         .knows_txdone = true,
 356 };
 357
 358 static int acpi_get_psd(struct cpc_desc *cpc_ptr, acpi_handle handle)
 359 {
 360         int result = -EFAULT;
 361         acpi_status status = AE_OK;
 362         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 363         struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
 364         struct acpi_buffer state = {0, NULL};
 365         union acpi_object  *psd = NULL;
 366         struct acpi_psd_package *pdomain;
 367
 368         status = acpi_evaluate_object_typed(handle, "_PSD", NULL,
 369                                             &buffer, ACPI_TYPE_PACKAGE);
 370         if (status == AE_NOT_FOUND)     /* _PSD is optional */
 371                 return 0;
 372         if (ACPI_FAILURE(status))
 373                 return -ENODEV;
 374
 375         psd = buffer.pointer;
 376         if (!psd || psd->package.count != 1) {
 377                 pr_debug("Invalid _PSD data\n");
 378                 goto end;
 379         }
 380
 381         pdomain = &(cpc_ptr->domain_info);
 382
 383         state.length = sizeof(struct acpi_psd_package);
 384         state.pointer = pdomain;
 385
 386         status = acpi_extract_package(&(psd->package.elements[0]),
 387                 &format, &state);
 388         if (ACPI_FAILURE(status)) {
 389                 pr_debug("Invalid _PSD data for CPU:%d\n", cpc_ptr->cpu_id);
 390                 goto end;
 391         }
 392
 393         if (pdomain->num_entries != ACPI_PSD_REV0_ENTRIES) {
 394                 pr_debug("Unknown _PSD:num_entries for CPU:%d\n", cpc_ptr->cpu_id);
 395                 goto end;
 396         }
 397
 398         if (pdomain->revision != ACPI_PSD_REV0_REVISION) {
 399                 pr_debug("Unknown _PSD:revision for CPU: %d\n", cpc_ptr->cpu_id);
 400                 goto end;
 401         }
 402
 403         if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
 404             pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
 405             pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
 406                 pr_debug("Invalid _PSD:coord_type for CPU:%d\n", cpc_ptr->cpu_id);
 407                 goto end;
 408         }
 409
 410         result = 0;
 411 end:
 412         kfree(buffer.pointer);
 413         return result;
 414 }
 415
 416 /**
 417  * acpi_get_psd_map - Map the CPUs in a common freq domain.
 418  * @all_cpu_data: Ptrs to CPU specific CPPC data including PSD info.
 419  *
 420  *      Return: 0 for success or negative value for err.
 421  */
 422 int acpi_get_psd_map(struct cppc_cpudata **all_cpu_data)
 423 {
 424         int count_target;
 425         int retval = 0;
 426         unsigned int i, j;
 427         cpumask_var_t covered_cpus;
 428         struct cppc_cpudata *pr, *match_pr;
 429         struct acpi_psd_package *pdomain;
 430         struct acpi_psd_package *match_pdomain;
 431         struct cpc_desc *cpc_ptr, *match_cpc_ptr;
 432
 433         if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
 434                 return -ENOMEM;
 435
 436         /*
 437          * Now that we have _PSD data from all CPUs, let's setup P-state
 438          * domain info.
 439          */
 440         for_each_possible_cpu(i) {
 441                 if (cpumask_test_cpu(i, covered_cpus))
 442                         continue;
 443
 444                 pr = all_cpu_data[i];
 445                 cpc_ptr = per_cpu(cpc_desc_ptr, i);
 446                 if (!cpc_ptr) {
 447                         retval = -EFAULT;
 448                         goto err_ret;
 449                 }
 450
 451                 pdomain = &(cpc_ptr->domain_info);
 452                 cpumask_set_cpu(i, pr->shared_cpu_map);
 453                 cpumask_set_cpu(i, covered_cpus);
 454                 if (pdomain->num_processors <= 1)
 455                         continue;
 456
 457                 /* Validate the Domain info */
 458                 count_target = pdomain->num_processors;
 459                 if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
 460                         pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 461                 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
 462                         pr->shared_type = CPUFREQ_SHARED_TYPE_HW;
 463                 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
 464                         pr->shared_type = CPUFREQ_SHARED_TYPE_ANY;
 465
 466                 for_each_possible_cpu(j) {
 467                         if (i == j)
 468                                 continue;
 469
 470                         match_cpc_ptr = per_cpu(cpc_desc_ptr, j);
 471                         if (!match_cpc_ptr) {
 472                                 retval = -EFAULT;
 473                                 goto err_ret;
 474                         }
 475
 476                         match_pdomain = &(match_cpc_ptr->domain_info);
 477                         if (match_pdomain->domain != pdomain->domain)
 478                                 continue;
 479
 480                         /* Here i and j are in the same domain */
 481                         if (match_pdomain->num_processors != count_target) {
 482                                 retval = -EFAULT;
 483                                 goto err_ret;
 484                         }
 485
 486                         if (pdomain->coord_type != match_pdomain->coord_type) {
 487                                 retval = -EFAULT;
 488                                 goto err_ret;
 489                         }
 490
 491                         cpumask_set_cpu(j, covered_cpus);
 492                         cpumask_set_cpu(j, pr->shared_cpu_map);
 493                 }
 494
 495                 for_each_cpu(j, pr->shared_cpu_map) {
 496                         if (i == j)
 497                                 continue;
 498
 499                         match_pr = all_cpu_data[j];
 500                         match_pr->shared_type = pr->shared_type;
 501                         cpumask_copy(match_pr->shared_cpu_map,
 502                                      pr->shared_cpu_map);
 503                 }
 504         }
 505         goto out;
 506
 507 err_ret:
 508         for_each_possible_cpu(i) {
 509                 pr = all_cpu_data[i];
 510
 511                 /* Assume no coordination on any error parsing domain info */
 512                 cpumask_clear(pr->shared_cpu_map);
 513                 cpumask_set_cpu(i, pr->shared_cpu_map);
 514                 pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 515         }
 516 out:
 517         free_cpumask_var(covered_cpus);
 518         return retval;
 519 }
 520 EXPORT_SYMBOL_GPL(acpi_get_psd_map);
 521
 522 static int register_pcc_channel(int pcc_ss_idx)
 523 {
 524         struct acpi_pcct_hw_reduced *cppc_ss;
 525         u64 usecs_lat;
 526
 527         if (pcc_ss_idx >= 0) {
 528                 pcc_data[pcc_ss_idx]->pcc_channel =
 529                         pcc_mbox_request_channel(&cppc_mbox_cl, pcc_ss_idx);
 530
 531                 if (IS_ERR(pcc_data[pcc_ss_idx]->pcc_channel)) {
 532                         pr_err("Failed to find PCC channel for subspace %d\n",
 533                                pcc_ss_idx);
 534                         return -ENODEV;
 535                 }
 536
 537                 /*
 538                  * The PCC mailbox controller driver should
 539                  * have parsed the PCCT (global table of all
 540                  * PCC channels) and stored pointers to the
 541                  * subspace communication region in con_priv.
 542                  */
 543                 cppc_ss = (pcc_data[pcc_ss_idx]->pcc_channel)->con_priv;
 544
 545                 if (!cppc_ss) {
 546                         pr_err("No PCC subspace found for %d CPPC\n",
 547                                pcc_ss_idx);
 548                         return -ENODEV;
 549                 }
 550
 551                 /*
 552                  * cppc_ss->latency is just a Nominal value. In reality
 553                  * the remote processor could be much slower to reply.
 554                  * So add an arbitrary amount of wait on top of Nominal.
 555                  */
 556                 usecs_lat = NUM_RETRIES * cppc_ss->latency;
 557                 pcc_data[pcc_ss_idx]->deadline_us = usecs_lat;
 558                 pcc_data[pcc_ss_idx]->pcc_mrtt = cppc_ss->min_turnaround_time;
 559                 pcc_data[pcc_ss_idx]->pcc_mpar = cppc_ss->max_access_rate;
 560                 pcc_data[pcc_ss_idx]->pcc_nominal = cppc_ss->latency;
 561
 562                 pcc_data[pcc_ss_idx]->pcc_comm_addr =
 563                         acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
 564                 if (!pcc_data[pcc_ss_idx]->pcc_comm_addr) {
 565                         pr_err("Failed to ioremap PCC comm region mem for %d\n",
 566                                pcc_ss_idx);
 567                         return -ENOMEM;
 568                 }
 569
 570                 /* Set flag so that we don't come here for each CPU. */
 571                 pcc_data[pcc_ss_idx]->pcc_channel_acquired = true;
 572         }
 573
 574         return 0;
 575 }
 576
 577 /**
 578  * cpc_ffh_supported() - check if FFH reading supported
 579  *
 580  * Check if the architecture has support for functional fixed hardware
 581  * read/write capability.
 582  *
 583  * Return: true for supported, false for not supported
 584  */
 585 bool __weak cpc_ffh_supported(void)
 586 {
 587         return false;
 588 }
 589
 590 /**
 591  * pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
 592  *
 593  * Check and allocate the cppc_pcc_data memory.
 594  * In some processor configurations it is possible that same subspace
 595  * is shared between multiple CPUs. This is seen especially in CPUs
 596  * with hardware multi-threading support.
 597  *
 598  * Return: 0 for success, errno for failure
 599  */
 600 int pcc_data_alloc(int pcc_ss_id)
 601 {
 602         if (pcc_ss_id < 0 || pcc_ss_id >= MAX_PCC_SUBSPACES)
 603                 return -EINVAL;
 604
 605         if (pcc_data[pcc_ss_id]) {
 606                 pcc_data[pcc_ss_id]->refcount++;
 607         } else {
 608                 pcc_data[pcc_ss_id] = kzalloc(sizeof(struct cppc_pcc_data),
 609                                               GFP_KERNEL);
 610                 if (!pcc_data[pcc_ss_id])
 611                         return -ENOMEM;
 612                 pcc_data[pcc_ss_id]->refcount++;
 613         }
 614
 615         return 0;
 616 }
 617
 618 /* Check if CPPC revision + num_ent combination is supported */
 619 static bool is_cppc_supported(int revision, int num_ent)
 620 {
 621         int expected_num_ent;
 622
 623         switch (revision) {
 624         case CPPC_V2_REV:
 625                 expected_num_ent = CPPC_V2_NUM_ENT;
 626                 break;
 627         case CPPC_V3_REV:
 628                 expected_num_ent = CPPC_V3_NUM_ENT;
 629                 break;
 630         default:
 631                 pr_debug("Firmware exports unsupported CPPC revision: %d\n",
 632                         revision);
 633                 return false;
 634         }
 635
 636         if (expected_num_ent != num_ent) {
 637                 pr_debug("Firmware exports %d entries. Expected: %d for CPPC rev:%d\n",
 638                         num_ent, expected_num_ent, revision);
 639                 return false;
 640         }
 641
 642         return true;
 643 }
 644
 645 /*
 646  * An example CPC table looks like the following.
 647  *
 648  *      Name(_CPC, Package()
 649  *                      {
 650  *                      17,
 651  *                      NumEntries
 652  *                      1,
 653  *                      // Revision
 654  *                      ResourceTemplate(){Register(PCC, 32, 0, 0x120, 2)},
 655  *                      // Highest Performance
 656  *                      ResourceTemplate(){Register(PCC, 32, 0, 0x124, 2)},
 657  *                      // Nominal Performance
 658  *                      ResourceTemplate(){Register(PCC, 32, 0, 0x128, 2)},
 659  *                      // Lowest Nonlinear Performance
 660  *                      ResourceTemplate(){Register(PCC, 32, 0, 0x12C, 2)},
 661  *                      // Lowest Performance
 662  *                      ResourceTemplate(){Register(PCC, 32, 0, 0x130, 2)},
 663  *                      // Guaranteed Performance Register
 664  *                      ResourceTemplate(){Register(PCC, 32, 0, 0x110, 2)},
 665  *                      // Desired Performance Register
 666  *                      ResourceTemplate(){Register(SystemMemory, 0, 0, 0, 0)},
 667  *                      ..
 668  *                      ..
 669  *                      ..
 670  *
 671  *              }
 672  * Each Register() encodes how to access that specific register.
 673  * e.g. a sample PCC entry has the following encoding:
 674  *
 675  *      Register (
 676  *              PCC,
 677  *              AddressSpaceKeyword
 678  *              8,
 679  *              //RegisterBitWidth
 680  *              8,
 681  *              //RegisterBitOffset
 682  *              0x30,
 683  *              //RegisterAddress
 684  *              9
 685  *              //AccessSize (subspace ID)
 686  *              0
 687  *              )
 688  *      }
 689  */
 690
 691 /**
 692  * acpi_cppc_processor_probe - Search for per CPU _CPC objects.
 693  * @pr: Ptr to acpi_processor containing this CPU's logical ID.
 694  *
 695  *      Return: 0 for success or negative value for err.
 696  */
 697 int acpi_cppc_processor_probe(struct acpi_processor *pr)
 698 {
 699         struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 700         union acpi_object *out_obj, *cpc_obj;
 701         struct cpc_desc *cpc_ptr;
 702         struct cpc_reg *gas_t;
 703         struct device *cpu_dev;
 704         acpi_handle handle = pr->handle;
 705         unsigned int num_ent, i, cpc_rev;
 706         int pcc_subspace_id = -1;
 707         acpi_status status;
 708         int ret = -EFAULT;
 709
 710         /* Parse the ACPI _CPC table for this CPU. */
 711         status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
 712                         ACPI_TYPE_PACKAGE);
 713         if (ACPI_FAILURE(status)) {
 714                 ret = -ENODEV;
 715                 goto out_buf_free;
 716         }
 717
 718         out_obj = (union acpi_object *) output.pointer;
 719
 720         cpc_ptr = kzalloc(sizeof(struct cpc_desc), GFP_KERNEL);
 721         if (!cpc_ptr) {
 722                 ret = -ENOMEM;
 723                 goto out_buf_free;
 724         }
 725
 726         /* First entry is NumEntries. */
 727         cpc_obj = &out_obj->package.elements[0];
 728         if (cpc_obj->type == ACPI_TYPE_INTEGER) {
 729                 num_ent = cpc_obj->integer.value;
 730         } else {
 731                 pr_debug("Unexpected entry type(%d) for NumEntries\n",
 732                                 cpc_obj->type);
 733                 goto out_free;
 734         }
 735         cpc_ptr->num_entries = num_ent;
 736
 737         /* Second entry should be revision. */
 738         cpc_obj = &out_obj->package.elements[1];
 739         if (cpc_obj->type == ACPI_TYPE_INTEGER) {
 740                 cpc_rev = cpc_obj->integer.value;
 741         } else {
 742                 pr_debug("Unexpected entry type(%d) for Revision\n",
 743                                 cpc_obj->type);
 744                 goto out_free;
 745         }
 746         cpc_ptr->version = cpc_rev;
 747
 748         if (!is_cppc_supported(cpc_rev, num_ent))
 749                 goto out_free;
 750
 751         /* Iterate through remaining entries in _CPC */
 752         for (i = 2; i < num_ent; i++) {
 753                 cpc_obj = &out_obj->package.elements[i];
 754
 755                 if (cpc_obj->type == ACPI_TYPE_INTEGER) {
 756                         cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_INTEGER;
 757                         cpc_ptr->cpc_regs[i-2].cpc_entry.int_value = cpc_obj->integer.value;
 758                 } else if (cpc_obj->type == ACPI_TYPE_BUFFER) {
 759                         gas_t = (struct cpc_reg *)
 760                                 cpc_obj->buffer.pointer;
 761
 762                         /*
 763                          * The PCC Subspace index is encoded inside
 764                          * the CPC table entries. The same PCC index
 765                          * will be used for all the PCC entries,
 766                          * so extract it only once.
 767                          */
 768                         if (gas_t->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
 769                                 if (pcc_subspace_id < 0) {
 770                                         pcc_subspace_id = gas_t->access_width;
 771                                         if (pcc_data_alloc(pcc_subspace_id))
 772                                                 goto out_free;
 773                                 } else if (pcc_subspace_id != gas_t->access_width) {
 774                                         pr_debug("Mismatched PCC ids.\n");
 775                                         goto out_free;
 776                                 }
 777                         } else if (gas_t->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 778                                 if (gas_t->address) {
 779                                         void __iomem *addr;
 780
 781                                         addr = ioremap(gas_t->address, gas_t->bit_width/8);
 782                                         if (!addr)
 783                                                 goto out_free;
 784                                         cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
 785                                 }
 786                         } else {
 787                                 if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
 788                                         /* Support only PCC ,SYS MEM and FFH type regs */
 789                                         pr_debug("Unsupported register type: %d\n", gas_t->space_id);
 790                                         goto out_free;
 791                                 }
 792                         }
 793
 794                         cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_BUFFER;
 795                         memcpy(&cpc_ptr->cpc_regs[i-2].cpc_entry.reg, gas_t, sizeof(*gas_t));
 796                 } else {
 797                         pr_debug("Err in entry:%d in CPC table of CPU:%d \n", i, pr->id);
 798                         goto out_free;
 799                 }
 800         }
 801         per_cpu(cpu_pcc_subspace_idx, pr->id) = pcc_subspace_id;
 802
 803         /*
 804          * Initialize the remaining cpc_regs as unsupported.
 805          * Example: In case FW exposes CPPC v2, the below loop will initialize
 806          * LOWEST_FREQ and NOMINAL_FREQ regs as unsupported
 807          */
 808         for (i = num_ent - 2; i < MAX_CPC_REG_ENT; i++) {
 809                 cpc_ptr->cpc_regs[i].type = ACPI_TYPE_INTEGER;
 810                 cpc_ptr->cpc_regs[i].cpc_entry.int_value = 0;
 811         }
 812
 813
 814         /* Store CPU Logical ID */
 815         cpc_ptr->cpu_id = pr->id;
 816
 817         /* Parse PSD data for this CPU */
 818         ret = acpi_get_psd(cpc_ptr, handle);
 819         if (ret)
 820                 goto out_free;
 821
 822         /* Register PCC channel once for all PCC subspace ID. */
 823         if (pcc_subspace_id >= 0 && !pcc_data[pcc_subspace_id]->pcc_channel_acquired) {
 824                 ret = register_pcc_channel(pcc_subspace_id);
 825                 if (ret)
 826                         goto out_free;
 827
 828                 init_rwsem(&pcc_data[pcc_subspace_id]->pcc_lock);
 829                 init_waitqueue_head(&pcc_data[pcc_subspace_id]->pcc_write_wait_q);
 830         }
 831
 832         /* Everything looks okay */
 833         pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);
 834
 835         /* Add per logical CPU nodes for reading its feedback counters. */
 836         cpu_dev = get_cpu_device(pr->id);
 837         if (!cpu_dev) {
 838                 ret = -EINVAL;
 839                 goto out_free;
 840         }
 841
 842         /* Plug PSD data into this CPU's CPC descriptor. */
 843         per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
 844
 845         ret = kobject_init_and_add(&cpc_ptr->kobj, &cppc_ktype, &cpu_dev->kobj,
 846                         "acpi_cppc");
 847         if (ret) {
 848                 per_cpu(cpc_desc_ptr, pr->id) = NULL;
 849                 goto out_free;
 850         }
 851
 852         kfree(output.pointer);
 853         return 0;
 854
 855 out_free:
 856         /* Free all the mapped sys mem areas for this CPU */
 857         for (i = 2; i < cpc_ptr->num_entries; i++) {
 858                 void __iomem *addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;
 859
 860                 if (addr)
 861                         iounmap(addr);
 862         }
 863         kfree(cpc_ptr);
 864
 865 out_buf_free:
 866         kfree(output.pointer);
 867         return ret;
 868 }
 869 EXPORT_SYMBOL_GPL(acpi_cppc_processor_probe);
 870
 871 /**
 872  * acpi_cppc_processor_exit - Cleanup CPC structs.
 873  * @pr: Ptr to acpi_processor containing this CPU's logical ID.
 874  *
 875  * Return: Void
 876  */
 877 void acpi_cppc_processor_exit(struct acpi_processor *pr)
 878 {
 879         struct cpc_desc *cpc_ptr;
 880         unsigned int i;
 881         void __iomem *addr;
 882         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, pr->id);
 883
 884         if (pcc_ss_id >=0 && pcc_data[pcc_ss_id]) {
 885                 if (pcc_data[pcc_ss_id]->pcc_channel_acquired) {
 886                         pcc_data[pcc_ss_id]->refcount--;
 887                         if (!pcc_data[pcc_ss_id]->refcount) {
 888                                 pcc_mbox_free_channel(pcc_data[pcc_ss_id]->pcc_channel);
 889                                 kfree(pcc_data[pcc_ss_id]);
 890                                 pcc_data[pcc_ss_id] = NULL;
 891                         }
 892                 }
 893         }
 894
 895         cpc_ptr = per_cpu(cpc_desc_ptr, pr->id);
 896         if (!cpc_ptr)
 897                 return;
 898
 899         /* Free all the mapped sys mem areas for this CPU */
 900         for (i = 2; i < cpc_ptr->num_entries; i++) {
 901                 addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;
 902                 if (addr)
 903                         iounmap(addr);
 904         }
 905
 906         kobject_put(&cpc_ptr->kobj);
 907         kfree(cpc_ptr);
 908 }
 909 EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
 910
 911 /**
 912  * cpc_read_ffh() - Read FFH register
 913  * @cpunum:     CPU number to read
 914  * @reg:        cppc register information
 915  * @val:        place holder for return value
 916  *
 917  * Read bit_width bits from a specified address and bit_offset
 918  *
 919  * Return: 0 for success and error code
 920  */
 921 int __weak cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
 922 {
 923         return -ENOTSUPP;
 924 }
 925
 926 /**
 927  * cpc_write_ffh() - Write FFH register
 928  * @cpunum:     CPU number to write
 929  * @reg:        cppc register information
 930  * @val:        value to write
 931  *
 932  * Write value of bit_width bits to a specified address and bit_offset
 933  *
 934  * Return: 0 for success and error code
 935  */
 936 int __weak cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
 937 {
 938         return -ENOTSUPP;
 939 }
 940
 941 /*
 942  * Since cpc_read and cpc_write are called while holding pcc_lock, it should be
 943  * as fast as possible. We have already mapped the PCC subspace during init, so
 944  * we can directly write to it.
 945  */
 946
 947 static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 948 {
 949         int ret_val = 0;
 950         void __iomem *vaddr = 0;
 951         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 952         struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 953
 954         if (reg_res->type == ACPI_TYPE_INTEGER) {
 955                 *val = reg_res->cpc_entry.int_value;
 956                 return ret_val;
 957         }
 958
 959         *val = 0;
 960         if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
 961                 vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
 962         else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
 963                 vaddr = reg_res->sys_mem_vaddr;
 964         else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
 965                 return cpc_read_ffh(cpu, reg, val);
 966         else
 967                 return acpi_os_read_memory((acpi_physical_address)reg->address,
 968                                 val, reg->bit_width);
 969
 970         switch (reg->bit_width) {
 971                 case 8:
 972                         *val = readb_relaxed(vaddr);
 973                         break;
 974                 case 16:
 975                         *val = readw_relaxed(vaddr);
 976                         break;
 977                 case 32:
 978                         *val = readl_relaxed(vaddr);
 979                         break;
 980                 case 64:
 981                         *val = readq_relaxed(vaddr);
 982                         break;
 983                 default:
 984                         pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
 985                                  reg->bit_width, pcc_ss_id);
 986                         ret_val = -EFAULT;
 987         }
 988
 989         return ret_val;
 990 }
 991
 992 static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 993 {
 994         int ret_val = 0;
 995         void __iomem *vaddr = 0;
 996         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 997         struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 998
 999         if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
1000                 vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
1001         else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
1002                 vaddr = reg_res->sys_mem_vaddr;
1003         else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
1004                 return cpc_write_ffh(cpu, reg, val);
1005         else
1006                 return acpi_os_write_memory((acpi_physical_address)reg->address,
1007                                 val, reg->bit_width);
1008
1009         switch (reg->bit_width) {
1010                 case 8:
1011                         writeb_relaxed(val, vaddr);
1012                         break;
1013                 case 16:
1014                         writew_relaxed(val, vaddr);
1015                         break;
1016                 case 32:
1017                         writel_relaxed(val, vaddr);
1018                         break;
1019                 case 64:
1020                         writeq_relaxed(val, vaddr);
1021                         break;
1022                 default:
1023                         pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
1024                                  reg->bit_width, pcc_ss_id);
1025                         ret_val = -EFAULT;
1026                         break;
1027         }
1028
1029         return ret_val;
1030 }
1031
1032 /**
1033  * cppc_get_desired_perf - Get the value of desired performance register.
1034  * @cpunum: CPU from which to get desired performance.
1035  * @desired_perf: address of a variable to store the returned desired performance
1036  *
1037  * Return: 0 for success, -EIO otherwise.
1038  */
1039 int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
1040 {
1041         struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
1042         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
1043         struct cpc_register_resource *desired_reg;
1044         struct cppc_pcc_data *pcc_ss_data = NULL;
1045
1046         desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
1047
1048         if (CPC_IN_PCC(desired_reg)) {
1049                 int ret = 0;
1050
1051                 if (pcc_ss_id < 0)
1052                         return -EIO;
1053
1054                 pcc_ss_data = pcc_data[pcc_ss_id];
1055
1056                 down_write(&pcc_ss_data->pcc_lock);
1057
1058                 if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
1059                         cpc_read(cpunum, desired_reg, desired_perf);
1060                 else
1061                         ret = -EIO;
1062
1063                 up_write(&pcc_ss_data->pcc_lock);
1064
1065                 return ret;
1066         }
1067
1068         cpc_read(cpunum, desired_reg, desired_perf);
1069
1070         return 0;
1071 }
1072 EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
1073
1074 /**
1075  * cppc_get_perf_caps - Get a CPU's performance capabilities.
1076  * @cpunum: CPU from which to get capabilities info.
1077  * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
1078  *
1079  * Return: 0 for success with perf_caps populated else -ERRNO.
1080  */
1081 int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
1082 {
1083         struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
1084         struct cpc_register_resource *highest_reg, *lowest_reg,
1085                 *lowest_non_linear_reg, *nominal_reg, *guaranteed_reg,
1086                 *low_freq_reg = NULL, *nom_freq_reg = NULL;
1087         u64 high, low, guaranteed, nom, min_nonlinear, low_f = 0, nom_f = 0;
1088         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
1089         struct cppc_pcc_data *pcc_ss_data = NULL;
1090         int ret = 0, regs_in_pcc = 0;
1091
1092         if (!cpc_desc) {
1093                 pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
1094                 return -ENODEV;
1095         }
1096
1097         highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
1098         lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
1099         lowest_non_linear_reg = &cpc_desc->cpc_regs[LOW_NON_LINEAR_PERF];
1100         nominal_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
1101         low_freq_reg = &cpc_desc->cpc_regs[LOWEST_FREQ];
1102         nom_freq_reg = &cpc_desc->cpc_regs[NOMINAL_FREQ];
1103         guaranteed_reg = &cpc_desc->cpc_regs[GUARANTEED_PERF];
1104
1105         /* Are any of the regs PCC ?*/
1106         if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
1107                 CPC_IN_PCC(lowest_non_linear_reg) || CPC_IN_PCC(nominal_reg) ||
1108                 CPC_IN_PCC(low_freq_reg) || CPC_IN_PCC(nom_freq_reg)) {
1109                 if (pcc_ss_id < 0) {
1110                         pr_debug("Invalid pcc_ss_id\n");
1111                         return -ENODEV;
1112                 }
1113                 pcc_ss_data = pcc_data[pcc_ss_id];
1114                 regs_in_pcc = 1;
1115                 down_write(&pcc_ss_data->pcc_lock);
1116                 /* Ring doorbell once to update PCC subspace */
1117                 if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
1118                         ret = -EIO;
1119                         goto out_err;
1120                 }
1121         }
1122
1123         cpc_read(cpunum, highest_reg, &high);
1124         perf_caps->highest_perf = high;
1125
1126         cpc_read(cpunum, lowest_reg, &low);
1127         perf_caps->lowest_perf = low;
1128
1129         cpc_read(cpunum, nominal_reg, &nom);
1130         perf_caps->nominal_perf = nom;
1131
1132         if (guaranteed_reg->type != ACPI_TYPE_BUFFER  ||
1133             IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) {
1134                 perf_caps->guaranteed_perf = 0;
1135         } else {
1136                 cpc_read(cpunum, guaranteed_reg, &guaranteed);
1137                 perf_caps->guaranteed_perf = guaranteed;
1138         }
1139
1140         cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
1141         perf_caps->lowest_nonlinear_perf = min_nonlinear;
1142
1143         if (!high || !low || !nom || !min_nonlinear)
1144                 ret = -EFAULT;
1145
1146         /* Read optional lowest and nominal frequencies if present */
1147         if (CPC_SUPPORTED(low_freq_reg))
1148                 cpc_read(cpunum, low_freq_reg, &low_f);
1149
1150         if (CPC_SUPPORTED(nom_freq_reg))
1151                 cpc_read(cpunum, nom_freq_reg, &nom_f);
1152
1153         perf_caps->lowest_freq = low_f;
1154         perf_caps->nominal_freq = nom_f;
1155
1156
1157 out_err:
1158         if (regs_in_pcc)
1159                 up_write(&pcc_ss_data->pcc_lock);
1160         return ret;
1161 }
1162 EXPORT_SYMBOL_GPL(cppc_get_perf_caps);
1163
1164 /**
1165  * cppc_get_perf_ctrs - Read a CPU's performance feedback counters.
1166  * @cpunum: CPU from which to read counters.
1167  * @perf_fb_ctrs: ptr to cppc_perf_fb_ctrs. See cppc_acpi.h
1168  *
1169  * Return: 0 for success with perf_fb_ctrs populated else -ERRNO.
1170  */
1171 int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
1172 {
1173         struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
1174         struct cpc_register_resource *delivered_reg, *reference_reg,
1175                 *ref_perf_reg, *ctr_wrap_reg;
1176         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
1177         struct cppc_pcc_data *pcc_ss_data = NULL;
1178         u64 delivered, reference, ref_perf, ctr_wrap_time;
1179         int ret = 0, regs_in_pcc = 0;
1180
1181         if (!cpc_desc) {
1182                 pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
1183                 return -ENODEV;
1184         }
1185
1186         delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
1187         reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
1188         ref_perf_reg = &cpc_desc->cpc_regs[REFERENCE_PERF];
1189         ctr_wrap_reg = &cpc_desc->cpc_regs[CTR_WRAP_TIME];
1190
1191         /*
1192          * If reference perf register is not supported then we should
1193          * use the nominal perf value
1194          */
1195         if (!CPC_SUPPORTED(ref_perf_reg))
1196                 ref_perf_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
1197
1198         /* Are any of the regs PCC ?*/
1199         if (CPC_IN_PCC(delivered_reg) || CPC_IN_PCC(reference_reg) ||
1200                 CPC_IN_PCC(ctr_wrap_reg) || CPC_IN_PCC(ref_perf_reg)) {
1201                 if (pcc_ss_id < 0) {
1202                         pr_debug("Invalid pcc_ss_id\n");
1203                         return -ENODEV;
1204                 }
1205                 pcc_ss_data = pcc_data[pcc_ss_id];
1206                 down_write(&pcc_ss_data->pcc_lock);
1207                 regs_in_pcc = 1;
1208                 /* Ring doorbell once to update PCC subspace */
1209                 if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
1210                         ret = -EIO;
1211                         goto out_err;
1212                 }
1213         }
1214
1215         cpc_read(cpunum, delivered_reg, &delivered);
1216         cpc_read(cpunum, reference_reg, &reference);
1217         cpc_read(cpunum, ref_perf_reg, &ref_perf);
1218
1219         /*
1220          * Per spec, if ctr_wrap_time optional register is unsupported, then the
1221          * performance counters are assumed to never wrap during the lifetime of
1222          * platform
1223          */
1224         ctr_wrap_time = (u64)(~((u64)0));
1225         if (CPC_SUPPORTED(ctr_wrap_reg))
1226                 cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);
1227
1228         if (!delivered || !reference || !ref_perf) {
1229                 ret = -EFAULT;
1230                 goto out_err;
1231         }
1232
1233         perf_fb_ctrs->delivered = delivered;
1234         perf_fb_ctrs->reference = reference;
1235         perf_fb_ctrs->reference_perf = ref_perf;
1236         perf_fb_ctrs->wraparound_time = ctr_wrap_time;
1237 out_err:
1238         if (regs_in_pcc)
1239                 up_write(&pcc_ss_data->pcc_lock);
1240         return ret;
1241 }
1242 EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);
1243
1244 /**
1245  * cppc_set_perf - Set a CPU's performance controls.
1246  * @cpu: CPU for which to set performance controls.
1247  * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
1248  *
1249  * Return: 0 for success, -ERRNO otherwise.
1250  */
1251 int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
1252 {
1253         struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
1254         struct cpc_register_resource *desired_reg;
1255         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
1256         struct cppc_pcc_data *pcc_ss_data = NULL;
1257         int ret = 0;
1258
1259         if (!cpc_desc) {
1260                 pr_debug("No CPC descriptor for CPU:%d\n", cpu);
1261                 return -ENODEV;
1262         }
1263
1264         desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
1265
1266         /*
1267          * This is Phase-I where we want to write to CPC registers
1268          * -> We want all CPUs to be able to execute this phase in parallel
1269          *
1270          * Since read_lock can be acquired by multiple CPUs simultaneously we
1271          * achieve that goal here
1272          */
1273         if (CPC_IN_PCC(desired_reg)) {
1274                 if (pcc_ss_id < 0) {
1275                         pr_debug("Invalid pcc_ss_id\n");
1276                         return -ENODEV;
1277                 }
1278                 pcc_ss_data = pcc_data[pcc_ss_id];
1279                 down_read(&pcc_ss_data->pcc_lock); /* BEGIN Phase-I */
1280                 if (pcc_ss_data->platform_owns_pcc) {
1281                         ret = check_pcc_chan(pcc_ss_id, false);
1282                         if (ret) {
1283                                 up_read(&pcc_ss_data->pcc_lock);
1284                                 return ret;
1285                         }
1286                 }
1287                 /*
1288                  * Update the pending_write to make sure a PCC CMD_READ will not
1289                  * arrive and steal the channel during the switch to write lock
1290                  */
1291                 pcc_ss_data->pending_pcc_write_cmd = true;
1292                 cpc_desc->write_cmd_id = pcc_ss_data->pcc_write_cnt;
1293                 cpc_desc->write_cmd_status = 0;
1294         }
1295
1296         /*
1297          * Skip writing MIN/MAX until Linux knows how to come up with
1298          * useful values.
1299          */
1300         cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);
1301
1302         if (CPC_IN_PCC(desired_reg))
1303                 up_read(&pcc_ss_data->pcc_lock);        /* END Phase-I */
1304         /*
1305          * This is Phase-II where we transfer the ownership of PCC to Platform
1306          *
1307          * Short Summary: Basically if we think of a group of cppc_set_perf
1308          * requests that happened in short overlapping interval. The last CPU to
1309          * come out of Phase-I will enter Phase-II and ring the doorbell.
1310          *
1311          * We have the following requirements for Phase-II:
1312          *     1. We want to execute Phase-II only when there are no CPUs
1313          * currently executing in Phase-I
1314          *     2. Once we start Phase-II we want to avoid all other CPUs from
1315          * entering Phase-I.
1316          *     3. We want only one CPU among all those who went through Phase-I
1317          * to run phase-II
1318          *
1319          * If write_trylock fails to get the lock and doesn't transfer the
1320          * PCC ownership to the platform, then one of the following will be TRUE
1321          *     1. There is at-least one CPU in Phase-I which will later execute
1322          * write_trylock, so the CPUs in Phase-I will be responsible for
1323          * executing the Phase-II.
1324          *     2. Some other CPU has beaten this CPU to successfully execute the
1325          * write_trylock and has already acquired the write_lock. We know for a
1326          * fact it (other CPU acquiring the write_lock) couldn't have happened
1327          * before this CPU's Phase-I as we held the read_lock.
1328          *     3. Some other CPU executing pcc CMD_READ has stolen the
1329          * down_write, in which case, send_pcc_cmd will check for pending
1330          * CMD_WRITE commands by checking the pending_pcc_write_cmd.
1331          * So this CPU can be certain that its request will be delivered
1332          *    So in all cases, this CPU knows that its request will be delivered
1333          * by another CPU and can return
1334          *
1335          * After getting the down_write we still need to check for
1336          * pending_pcc_write_cmd to take care of the following scenario
1337          *    The thread running this code could be scheduled out between
1338          * Phase-I and Phase-II. Before it is scheduled back on, another CPU
1339          * could have delivered the request to Platform by triggering the
1340          * doorbell and transferred the ownership of PCC to platform. So this
1341          * avoids triggering an unnecessary doorbell and more importantly before
1342          * triggering the doorbell it makes sure that the PCC channel ownership
1343          * is still with OSPM.
1344          *   pending_pcc_write_cmd can also be cleared by a different CPU, if
1345          * there was a pcc CMD_READ waiting on down_write and it steals the lock
1346          * before the pcc CMD_WRITE is completed. pcc_send_cmd checks for this
1347          * case during a CMD_READ and if there are pending writes it delivers
1348          * the write command before servicing the read command
1349          */
1350         if (CPC_IN_PCC(desired_reg)) {
1351                 if (down_write_trylock(&pcc_ss_data->pcc_lock)) {/* BEGIN Phase-II */
1352                         /* Update only if there are pending write commands */
1353                         if (pcc_ss_data->pending_pcc_write_cmd)
1354                                 send_pcc_cmd(pcc_ss_id, CMD_WRITE);
1355                         up_write(&pcc_ss_data->pcc_lock);       /* END Phase-II */
1356                 } else
1357                         /* Wait until pcc_write_cnt is updated by send_pcc_cmd */
1358                         wait_event(pcc_ss_data->pcc_write_wait_q,
1359                                    cpc_desc->write_cmd_id != pcc_ss_data->pcc_write_cnt);
1360
1361                 /* send_pcc_cmd updates the status in case of failure */
1362                 ret = cpc_desc->write_cmd_status;
1363         }
1364         return ret;
1365 }
1366 EXPORT_SYMBOL_GPL(cppc_set_perf);
1367
1368 /**
1369  * cppc_get_transition_latency - returns frequency transition latency in ns
1370  *
1371  * ACPI CPPC does not explicitly specifiy how a platform can specify the
1372  * transition latency for perfromance change requests. The closest we have
1373  * is the timing information from the PCCT tables which provides the info
1374  * on the number and frequency of PCC commands the platform can handle.
1375  */
1376 unsigned int cppc_get_transition_latency(int cpu_num)
1377 {
1378         /*
1379          * Expected transition latency is based on the PCCT timing values
1380          * Below are definition from ACPI spec:
1381          * pcc_nominal- Expected latency to process a command, in microseconds
1382          * pcc_mpar   - The maximum number of periodic requests that the subspace
1383          *              channel can support, reported in commands per minute. 0
1384          *              indicates no limitation.
1385          * pcc_mrtt   - The minimum amount of time that OSPM must wait after the
1386          *              completion of a command before issuing the next command,
1387          *              in microseconds.
1388          */
1389         unsigned int latency_ns = 0;
1390         struct cpc_desc *cpc_desc;
1391         struct cpc_register_resource *desired_reg;
1392         int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu_num);
1393         struct cppc_pcc_data *pcc_ss_data;
1394
1395         cpc_desc = per_cpu(cpc_desc_ptr, cpu_num);
1396         if (!cpc_desc)
1397                 return CPUFREQ_ETERNAL;
1398
1399         desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
1400         if (!CPC_IN_PCC(desired_reg))
1401                 return CPUFREQ_ETERNAL;
1402
1403         if (pcc_ss_id < 0)
1404                 return CPUFREQ_ETERNAL;
1405
1406         pcc_ss_data = pcc_data[pcc_ss_id];
1407         if (pcc_ss_data->pcc_mpar)
1408                 latency_ns = 60 * (1000 * 1000 * 1000 / pcc_ss_data->pcc_mpar);
1409
1410         latency_ns = max(latency_ns, pcc_ss_data->pcc_nominal * 1000);
1411         latency_ns = max(latency_ns, pcc_ss_data->pcc_mrtt * 1000);
1412
1413         return latency_ns;
1414 }
1415 EXPORT_SYMBOL_GPL(cppc_get_transition_latency);