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