cppc_acpi.c 41 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434
// SPDX-License-Identifier: GPL-2.0-only
/*
 * CPPC (Collaborative Processor Performance Control) methods used by CPUfreq drivers.
 *
 * (C) Copyright 2014, 2015 Linaro Ltd.
 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
 *
 * CPPC describes a few methods for controlling CPU performance using
 * information from a per CPU table called CPC. This table is described in
 * the ACPI v5.0+ specification. The table consists of a list of
 * registers which may be memory mapped or hardware registers and also may
 * include some static integer values.
 *
 * CPU performance is on an abstract continuous scale as against a discretized
 * P-state scale which is tied to CPU frequency only. In brief, the basic
 * operation involves:
 *
 * - OS makes a CPU performance request. (Can provide min and max bounds)
 *
 * - Platform (such as BMC) is free to optimize request within requested bounds
 *   depending on power/thermal budgets etc.
 *
 * - Platform conveys its decision back to OS
 *
 * The communication between OS and platform occurs through another medium
 * called (PCC) Platform Communication Channel. This is a generic mailbox like
 * mechanism which includes doorbell semantics to indicate register updates.
 * See drivers/mailbox/pcc.c for details on PCC.
 *
 * Finer details about the PCC and CPPC spec are available in the ACPI v5.1 and
 * above specifications.
 */

#define pr_fmt(fmt)	"ACPI CPPC: " fmt

#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/iopoll.h>
#include <linux/ktime.h>
#include <linux/rwsem.h>
#include <linux/wait.h>

#include <acpi/cppc_acpi.h>

struct cppc_pcc_data {
	struct mbox_chan *pcc_channel;
	void __iomem *pcc_comm_addr;
	bool pcc_channel_acquired;
	unsigned int deadline_us;
	unsigned int pcc_mpar, pcc_mrtt, pcc_nominal;

	bool pending_pcc_write_cmd;	/* Any pending/batched PCC write cmds? */
	bool platform_owns_pcc;		/* Ownership of PCC subspace */
	unsigned int pcc_write_cnt;	/* Running count of PCC write commands */

	/*
	 * Lock to provide controlled access to the PCC channel.
	 *
	 * For performance critical usecases(currently cppc_set_perf)
	 *	We need to take read_lock and check if channel belongs to OSPM
	 * before reading or writing to PCC subspace
	 *	We need to take write_lock before transferring the channel
	 * ownership to the platform via a Doorbell
	 *	This allows us to batch a number of CPPC requests if they happen
	 * to originate in about the same time
	 *
	 * For non-performance critical usecases(init)
	 *	Take write_lock for all purposes which gives exclusive access
	 */
	struct rw_semaphore pcc_lock;

	/* Wait queue for CPUs whose requests were batched */
	wait_queue_head_t pcc_write_wait_q;
	ktime_t last_cmd_cmpl_time;
	ktime_t last_mpar_reset;
	int mpar_count;
	int refcount;
};

/* Array to represent the PCC channel per subspace ID */
static struct cppc_pcc_data *pcc_data[MAX_PCC_SUBSPACES];
/* The cpu_pcc_subspace_idx contains per CPU subspace ID */
static DEFINE_PER_CPU(int, cpu_pcc_subspace_idx);

/*
 * The cpc_desc structure contains the ACPI register details
 * as described in the per CPU _CPC tables. The details
 * include the type of register (e.g. PCC, System IO, FFH etc.)
 * and destination addresses which lets us READ/WRITE CPU performance
 * information using the appropriate I/O methods.
 */
static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);

/* pcc mapped address + header size + offset within PCC subspace */
#define GET_PCC_VADDR(offs, pcc_ss_id) (pcc_data[pcc_ss_id]->pcc_comm_addr + \
						0x8 + (offs))

/* Check if a CPC register is in PCC */
#define CPC_IN_PCC(cpc) ((cpc)->type == ACPI_TYPE_BUFFER &&		\
				(cpc)->cpc_entry.reg.space_id ==	\
				ACPI_ADR_SPACE_PLATFORM_COMM)

/* Evalutes to True if reg is a NULL register descriptor */
#define IS_NULL_REG(reg) ((reg)->space_id ==  ACPI_ADR_SPACE_SYSTEM_MEMORY && \
				(reg)->address == 0 &&			\
				(reg)->bit_width == 0 &&		\
				(reg)->bit_offset == 0 &&		\
				(reg)->access_width == 0)

/* Evalutes to True if an optional cpc field is supported */
#define CPC_SUPPORTED(cpc) ((cpc)->type == ACPI_TYPE_INTEGER ?		\
				!!(cpc)->cpc_entry.int_value :		\
				!IS_NULL_REG(&(cpc)->cpc_entry.reg))
/*
 * Arbitrary Retries in case the remote processor is slow to respond
 * to PCC commands. Keeping it high enough to cover emulators where
 * the processors run painfully slow.
 */
#define NUM_RETRIES 500ULL

struct cppc_attr {
	struct attribute attr;
	ssize_t (*show)(struct kobject *kobj,
			struct attribute *attr, char *buf);
	ssize_t (*store)(struct kobject *kobj,
			struct attribute *attr, const char *c, ssize_t count);
};

#define define_one_cppc_ro(_name)		\
static struct cppc_attr _name =			\
__ATTR(_name, 0444, show_##_name, NULL)

#define to_cpc_desc(a) container_of(a, struct cpc_desc, kobj)

#define show_cppc_data(access_fn, struct_name, member_name)		\
	static ssize_t show_##member_name(struct kobject *kobj,		\
					struct attribute *attr,	char *buf) \
	{								\
		struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);		\
		struct struct_name st_name = {0};			\
		int ret;						\
									\
		ret = access_fn(cpc_ptr->cpu_id, &st_name);		\
		if (ret)						\
			return ret;					\
									\
		return scnprintf(buf, PAGE_SIZE, "%llu\n",		\
				(u64)st_name.member_name);		\
	}								\
	define_one_cppc_ro(member_name)

show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, highest_perf);
show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_perf);
show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_perf);
show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_nonlinear_perf);
show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_freq);
show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_freq);

show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, reference_perf);
show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time);

static ssize_t show_feedback_ctrs(struct kobject *kobj,
		struct attribute *attr, char *buf)
{
	struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);
	struct cppc_perf_fb_ctrs fb_ctrs = {0};
	int ret;

	ret = cppc_get_perf_ctrs(cpc_ptr->cpu_id, &fb_ctrs);
	if (ret)
		return ret;

	return scnprintf(buf, PAGE_SIZE, "ref:%llu del:%llu\n",
			fb_ctrs.reference, fb_ctrs.delivered);
}
define_one_cppc_ro(feedback_ctrs);

static struct attribute *cppc_attrs[] = {
	&feedback_ctrs.attr,
	&reference_perf.attr,
	&wraparound_time.attr,
	&highest_perf.attr,
	&lowest_perf.attr,
	&lowest_nonlinear_perf.attr,
	&nominal_perf.attr,
	&nominal_freq.attr,
	&lowest_freq.attr,
	NULL
};

static struct kobj_type cppc_ktype = {
	.sysfs_ops = &kobj_sysfs_ops,
	.default_attrs = cppc_attrs,
};

static int check_pcc_chan(int pcc_ss_id, bool chk_err_bit)
{
	int ret, status;
	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
	struct acpi_pcct_shared_memory __iomem *generic_comm_base =
		pcc_ss_data->pcc_comm_addr;

	if (!pcc_ss_data->platform_owns_pcc)
		return 0;

	/*
	 * Poll PCC status register every 3us(delay_us) for maximum of
	 * deadline_us(timeout_us) until PCC command complete bit is set(cond)
	 */
	ret = readw_relaxed_poll_timeout(&generic_comm_base->status, status,
					status & PCC_CMD_COMPLETE_MASK, 3,
					pcc_ss_data->deadline_us);

	if (likely(!ret)) {
		pcc_ss_data->platform_owns_pcc = false;
		if (chk_err_bit && (status & PCC_ERROR_MASK))
			ret = -EIO;
	}

	if (unlikely(ret))
		pr_err("PCC check channel failed for ss: %d. ret=%d\n",
		       pcc_ss_id, ret);

	return ret;
}

/*
 * This function transfers the ownership of the PCC to the platform
 * So it must be called while holding write_lock(pcc_lock)
 */
static int send_pcc_cmd(int pcc_ss_id, u16 cmd)
{
	int ret = -EIO, i;
	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
	struct acpi_pcct_shared_memory *generic_comm_base =
		(struct acpi_pcct_shared_memory *)pcc_ss_data->pcc_comm_addr;
	unsigned int time_delta;

	/*
	 * For CMD_WRITE we know for a fact the caller should have checked
	 * the channel before writing to PCC space
	 */
	if (cmd == CMD_READ) {
		/*
		 * If there are pending cpc_writes, then we stole the channel
		 * before write completion, so first send a WRITE command to
		 * platform
		 */
		if (pcc_ss_data->pending_pcc_write_cmd)
			send_pcc_cmd(pcc_ss_id, CMD_WRITE);

		ret = check_pcc_chan(pcc_ss_id, false);
		if (ret)
			goto end;
	} else /* CMD_WRITE */
		pcc_ss_data->pending_pcc_write_cmd = FALSE;

	/*
	 * Handle the Minimum Request Turnaround Time(MRTT)
	 * "The minimum amount of time that OSPM must wait after the completion
	 * of a command before issuing the next command, in microseconds"
	 */
	if (pcc_ss_data->pcc_mrtt) {
		time_delta = ktime_us_delta(ktime_get(),
					    pcc_ss_data->last_cmd_cmpl_time);
		if (pcc_ss_data->pcc_mrtt > time_delta)
			udelay(pcc_ss_data->pcc_mrtt - time_delta);
	}

	/*
	 * Handle the non-zero Maximum Periodic Access Rate(MPAR)
	 * "The maximum number of periodic requests that the subspace channel can
	 * support, reported in commands per minute. 0 indicates no limitation."
	 *
	 * This parameter should be ideally zero or large enough so that it can
	 * handle maximum number of requests that all the cores in the system can
	 * collectively generate. If it is not, we will follow the spec and just
	 * not send the request to the platform after hitting the MPAR limit in
	 * any 60s window
	 */
	if (pcc_ss_data->pcc_mpar) {
		if (pcc_ss_data->mpar_count == 0) {
			time_delta = ktime_ms_delta(ktime_get(),
						    pcc_ss_data->last_mpar_reset);
			if ((time_delta < 60 * MSEC_PER_SEC) && pcc_ss_data->last_mpar_reset) {
				pr_debug("PCC cmd for subspace %d not sent due to MPAR limit",
					 pcc_ss_id);
				ret = -EIO;
				goto end;
			}
			pcc_ss_data->last_mpar_reset = ktime_get();
			pcc_ss_data->mpar_count = pcc_ss_data->pcc_mpar;
		}
		pcc_ss_data->mpar_count--;
	}

	/* Write to the shared comm region. */
	writew_relaxed(cmd, &generic_comm_base->command);

	/* Flip CMD COMPLETE bit */
	writew_relaxed(0, &generic_comm_base->status);

	pcc_ss_data->platform_owns_pcc = true;

	/* Ring doorbell */
	ret = mbox_send_message(pcc_ss_data->pcc_channel, &cmd);
	if (ret < 0) {
		pr_err("Err sending PCC mbox message. ss: %d cmd:%d, ret:%d\n",
		       pcc_ss_id, cmd, ret);
		goto end;
	}

	/* wait for completion and check for PCC errro bit */
	ret = check_pcc_chan(pcc_ss_id, true);

	if (pcc_ss_data->pcc_mrtt)
		pcc_ss_data->last_cmd_cmpl_time = ktime_get();

	if (pcc_ss_data->pcc_channel->mbox->txdone_irq)
		mbox_chan_txdone(pcc_ss_data->pcc_channel, ret);
	else
		mbox_client_txdone(pcc_ss_data->pcc_channel, ret);

end:
	if (cmd == CMD_WRITE) {
		if (unlikely(ret)) {
			for_each_possible_cpu(i) {
				struct cpc_desc *desc = per_cpu(cpc_desc_ptr, i);
				if (!desc)
					continue;

				if (desc->write_cmd_id == pcc_ss_data->pcc_write_cnt)
					desc->write_cmd_status = ret;
			}
		}
		pcc_ss_data->pcc_write_cnt++;
		wake_up_all(&pcc_ss_data->pcc_write_wait_q);
	}

	return ret;
}

static void cppc_chan_tx_done(struct mbox_client *cl, void *msg, int ret)
{
	if (ret < 0)
		pr_debug("TX did not complete: CMD sent:%x, ret:%d\n",
				*(u16 *)msg, ret);
	else
		pr_debug("TX completed. CMD sent:%x, ret:%d\n",
				*(u16 *)msg, ret);
}

struct mbox_client cppc_mbox_cl = {
	.tx_done = cppc_chan_tx_done,
	.knows_txdone = true,
};

static int acpi_get_psd(struct cpc_desc *cpc_ptr, acpi_handle handle)
{
	int result = -EFAULT;
	acpi_status status = AE_OK;
	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
	struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
	struct acpi_buffer state = {0, NULL};
	union acpi_object  *psd = NULL;
	struct acpi_psd_package *pdomain;

	status = acpi_evaluate_object_typed(handle, "_PSD", NULL,
					    &buffer, ACPI_TYPE_PACKAGE);
	if (status == AE_NOT_FOUND)	/* _PSD is optional */
		return 0;
	if (ACPI_FAILURE(status))
		return -ENODEV;

	psd = buffer.pointer;
	if (!psd || psd->package.count != 1) {
		pr_debug("Invalid _PSD data\n");
		goto end;
	}

	pdomain = &(cpc_ptr->domain_info);

	state.length = sizeof(struct acpi_psd_package);
	state.pointer = pdomain;

	status = acpi_extract_package(&(psd->package.elements[0]),
		&format, &state);
	if (ACPI_FAILURE(status)) {
		pr_debug("Invalid _PSD data for CPU:%d\n", cpc_ptr->cpu_id);
		goto end;
	}

	if (pdomain->num_entries != ACPI_PSD_REV0_ENTRIES) {
		pr_debug("Unknown _PSD:num_entries for CPU:%d\n", cpc_ptr->cpu_id);
		goto end;
	}

	if (pdomain->revision != ACPI_PSD_REV0_REVISION) {
		pr_debug("Unknown _PSD:revision for CPU: %d\n", cpc_ptr->cpu_id);
		goto end;
	}

	if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
	    pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
	    pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
		pr_debug("Invalid _PSD:coord_type for CPU:%d\n", cpc_ptr->cpu_id);
		goto end;
	}

	result = 0;
end:
	kfree(buffer.pointer);
	return result;
}

/**
 * acpi_get_psd_map - Map the CPUs in a common freq domain.
 * @all_cpu_data: Ptrs to CPU specific CPPC data including PSD info.
 *
 *	Return: 0 for success or negative value for err.
 */
int acpi_get_psd_map(struct cppc_cpudata **all_cpu_data)
{
	int count_target;
	int retval = 0;
	unsigned int i, j;
	cpumask_var_t covered_cpus;
	struct cppc_cpudata *pr, *match_pr;
	struct acpi_psd_package *pdomain;
	struct acpi_psd_package *match_pdomain;
	struct cpc_desc *cpc_ptr, *match_cpc_ptr;

	if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
		return -ENOMEM;

	/*
	 * Now that we have _PSD data from all CPUs, let's setup P-state
	 * domain info.
	 */
	for_each_possible_cpu(i) {
		pr = all_cpu_data[i];
		if (!pr)
			continue;

		if (cpumask_test_cpu(i, covered_cpus))
			continue;

		cpc_ptr = per_cpu(cpc_desc_ptr, i);
		if (!cpc_ptr) {
			retval = -EFAULT;
			goto err_ret;
		}

		pdomain = &(cpc_ptr->domain_info);
		cpumask_set_cpu(i, pr->shared_cpu_map);
		cpumask_set_cpu(i, covered_cpus);
		if (pdomain->num_processors <= 1)
			continue;

		/* Validate the Domain info */
		count_target = pdomain->num_processors;
		if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
			pr->shared_type = CPUFREQ_SHARED_TYPE_HW;
		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
			pr->shared_type = CPUFREQ_SHARED_TYPE_ANY;

		for_each_possible_cpu(j) {
			if (i == j)
				continue;

			match_cpc_ptr = per_cpu(cpc_desc_ptr, j);
			if (!match_cpc_ptr) {
				retval = -EFAULT;
				goto err_ret;
			}

			match_pdomain = &(match_cpc_ptr->domain_info);
			if (match_pdomain->domain != pdomain->domain)
				continue;

			/* Here i and j are in the same domain */
			if (match_pdomain->num_processors != count_target) {
				retval = -EFAULT;
				goto err_ret;
			}

			if (pdomain->coord_type != match_pdomain->coord_type) {
				retval = -EFAULT;
				goto err_ret;
			}

			cpumask_set_cpu(j, covered_cpus);
			cpumask_set_cpu(j, pr->shared_cpu_map);
		}

		for_each_possible_cpu(j) {
			if (i == j)
				continue;

			match_pr = all_cpu_data[j];
			if (!match_pr)
				continue;

			match_cpc_ptr = per_cpu(cpc_desc_ptr, j);
			if (!match_cpc_ptr) {
				retval = -EFAULT;
				goto err_ret;
			}

			match_pdomain = &(match_cpc_ptr->domain_info);
			if (match_pdomain->domain != pdomain->domain)
				continue;

			match_pr->shared_type = pr->shared_type;
			cpumask_copy(match_pr->shared_cpu_map,
				     pr->shared_cpu_map);
		}
	}

err_ret:
	for_each_possible_cpu(i) {
		pr = all_cpu_data[i];
		if (!pr)
			continue;

		/* Assume no coordination on any error parsing domain info */
		if (retval) {
			cpumask_clear(pr->shared_cpu_map);
			cpumask_set_cpu(i, pr->shared_cpu_map);
			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
		}
	}

	free_cpumask_var(covered_cpus);
	return retval;
}
EXPORT_SYMBOL_GPL(acpi_get_psd_map);

static int register_pcc_channel(int pcc_ss_idx)
{
	struct acpi_pcct_hw_reduced *cppc_ss;
	u64 usecs_lat;

	if (pcc_ss_idx >= 0) {
		pcc_data[pcc_ss_idx]->pcc_channel =
			pcc_mbox_request_channel(&cppc_mbox_cl,	pcc_ss_idx);

		if (IS_ERR(pcc_data[pcc_ss_idx]->pcc_channel)) {
			pr_err("Failed to find PCC channel for subspace %d\n",
			       pcc_ss_idx);
			return -ENODEV;
		}

		/*
		 * The PCC mailbox controller driver should
		 * have parsed the PCCT (global table of all
		 * PCC channels) and stored pointers to the
		 * subspace communication region in con_priv.
		 */
		cppc_ss = (pcc_data[pcc_ss_idx]->pcc_channel)->con_priv;

		if (!cppc_ss) {
			pr_err("No PCC subspace found for %d CPPC\n",
			       pcc_ss_idx);
			return -ENODEV;
		}

		/*
		 * cppc_ss->latency is just a Nominal value. In reality
		 * the remote processor could be much slower to reply.
		 * So add an arbitrary amount of wait on top of Nominal.
		 */
		usecs_lat = NUM_RETRIES * cppc_ss->latency;
		pcc_data[pcc_ss_idx]->deadline_us = usecs_lat;
		pcc_data[pcc_ss_idx]->pcc_mrtt = cppc_ss->min_turnaround_time;
		pcc_data[pcc_ss_idx]->pcc_mpar = cppc_ss->max_access_rate;
		pcc_data[pcc_ss_idx]->pcc_nominal = cppc_ss->latency;

		pcc_data[pcc_ss_idx]->pcc_comm_addr =
			acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
		if (!pcc_data[pcc_ss_idx]->pcc_comm_addr) {
			pr_err("Failed to ioremap PCC comm region mem for %d\n",
			       pcc_ss_idx);
			return -ENOMEM;
		}

		/* Set flag so that we don't come here for each CPU. */
		pcc_data[pcc_ss_idx]->pcc_channel_acquired = true;
	}

	return 0;
}

/**
 * cpc_ffh_supported() - check if FFH reading supported
 *
 * Check if the architecture has support for functional fixed hardware
 * read/write capability.
 *
 * Return: true for supported, false for not supported
 */
bool __weak cpc_ffh_supported(void)
{
	return false;
}

/**
 * pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
 *
 * Check and allocate the cppc_pcc_data memory.
 * In some processor configurations it is possible that same subspace
 * is shared between multiple CPUs. This is seen especially in CPUs
 * with hardware multi-threading support.
 *
 * Return: 0 for success, errno for failure
 */
int pcc_data_alloc(int pcc_ss_id)
{
	if (pcc_ss_id < 0 || pcc_ss_id >= MAX_PCC_SUBSPACES)
		return -EINVAL;

	if (pcc_data[pcc_ss_id]) {
		pcc_data[pcc_ss_id]->refcount++;
	} else {
		pcc_data[pcc_ss_id] = kzalloc(sizeof(struct cppc_pcc_data),
					      GFP_KERNEL);
		if (!pcc_data[pcc_ss_id])
			return -ENOMEM;
		pcc_data[pcc_ss_id]->refcount++;
	}

	return 0;
}

/* Check if CPPC revision + num_ent combination is supported */
static bool is_cppc_supported(int revision, int num_ent)
{
	int expected_num_ent;

	switch (revision) {
	case CPPC_V2_REV:
		expected_num_ent = CPPC_V2_NUM_ENT;
		break;
	case CPPC_V3_REV:
		expected_num_ent = CPPC_V3_NUM_ENT;
		break;
	default:
		pr_debug("Firmware exports unsupported CPPC revision: %d\n",
			revision);
		return false;
	}

	if (expected_num_ent != num_ent) {
		pr_debug("Firmware exports %d entries. Expected: %d for CPPC rev:%d\n",
			num_ent, expected_num_ent, revision);
		return false;
	}

	return true;
}

/*
 * An example CPC table looks like the following.
 *
 *	Name(_CPC, Package()
 *			{
 *			17,
 *			NumEntries
 *			1,
 *			// Revision
 *			ResourceTemplate(){Register(PCC, 32, 0, 0x120, 2)},
 *			// Highest Performance
 *			ResourceTemplate(){Register(PCC, 32, 0, 0x124, 2)},
 *			// Nominal Performance
 *			ResourceTemplate(){Register(PCC, 32, 0, 0x128, 2)},
 *			// Lowest Nonlinear Performance
 *			ResourceTemplate(){Register(PCC, 32, 0, 0x12C, 2)},
 *			// Lowest Performance
 *			ResourceTemplate(){Register(PCC, 32, 0, 0x130, 2)},
 *			// Guaranteed Performance Register
 *			ResourceTemplate(){Register(PCC, 32, 0, 0x110, 2)},
 *			// Desired Performance Register
 *			ResourceTemplate(){Register(SystemMemory, 0, 0, 0, 0)},
 *			..
 *			..
 *			..
 *
 *		}
 * Each Register() encodes how to access that specific register.
 * e.g. a sample PCC entry has the following encoding:
 *
 *	Register (
 *		PCC,
 *		AddressSpaceKeyword
 *		8,
 *		//RegisterBitWidth
 *		8,
 *		//RegisterBitOffset
 *		0x30,
 *		//RegisterAddress
 *		9
 *		//AccessSize (subspace ID)
 *		0
 *		)
 *	}
 */

/**
 * acpi_cppc_processor_probe - Search for per CPU _CPC objects.
 * @pr: Ptr to acpi_processor containing this CPU's logical ID.
 *
 *	Return: 0 for success or negative value for err.
 */
int acpi_cppc_processor_probe(struct acpi_processor *pr)
{
	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
	union acpi_object *out_obj, *cpc_obj;
	struct cpc_desc *cpc_ptr;
	struct cpc_reg *gas_t;
	struct device *cpu_dev;
	acpi_handle handle = pr->handle;
	unsigned int num_ent, i, cpc_rev;
	int pcc_subspace_id = -1;
	acpi_status status;
	int ret = -EFAULT;

	/* Parse the ACPI _CPC table for this CPU. */
	status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
			ACPI_TYPE_PACKAGE);
	if (ACPI_FAILURE(status)) {
		ret = -ENODEV;
		goto out_buf_free;
	}

	out_obj = (union acpi_object *) output.pointer;

	cpc_ptr = kzalloc(sizeof(struct cpc_desc), GFP_KERNEL);
	if (!cpc_ptr) {
		ret = -ENOMEM;
		goto out_buf_free;
	}

	/* First entry is NumEntries. */
	cpc_obj = &out_obj->package.elements[0];
	if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
		num_ent = cpc_obj->integer.value;
	} else {
		pr_debug("Unexpected entry type(%d) for NumEntries\n",
				cpc_obj->type);
		goto out_free;
	}
	cpc_ptr->num_entries = num_ent;

	/* Second entry should be revision. */
	cpc_obj = &out_obj->package.elements[1];
	if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
		cpc_rev = cpc_obj->integer.value;
	} else {
		pr_debug("Unexpected entry type(%d) for Revision\n",
				cpc_obj->type);
		goto out_free;
	}
	cpc_ptr->version = cpc_rev;

	if (!is_cppc_supported(cpc_rev, num_ent))
		goto out_free;

	/* Iterate through remaining entries in _CPC */
	for (i = 2; i < num_ent; i++) {
		cpc_obj = &out_obj->package.elements[i];

		if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
			cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_INTEGER;
			cpc_ptr->cpc_regs[i-2].cpc_entry.int_value = cpc_obj->integer.value;
		} else if (cpc_obj->type == ACPI_TYPE_BUFFER) {
			gas_t = (struct cpc_reg *)
				cpc_obj->buffer.pointer;

			/*
			 * The PCC Subspace index is encoded inside
			 * the CPC table entries. The same PCC index
			 * will be used for all the PCC entries,
			 * so extract it only once.
			 */
			if (gas_t->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
				if (pcc_subspace_id < 0) {
					pcc_subspace_id = gas_t->access_width;
					if (pcc_data_alloc(pcc_subspace_id))
						goto out_free;
				} else if (pcc_subspace_id != gas_t->access_width) {
					pr_debug("Mismatched PCC ids.\n");
					goto out_free;
				}
			} else if (gas_t->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
				if (gas_t->address) {
					void __iomem *addr;

					addr = ioremap(gas_t->address, gas_t->bit_width/8);
					if (!addr)
						goto out_free;
					cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
				}
			} else {
				if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
					/* Support only PCC ,SYS MEM and FFH type regs */
					pr_debug("Unsupported register type: %d\n", gas_t->space_id);
					goto out_free;
				}
			}

			cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_BUFFER;
			memcpy(&cpc_ptr->cpc_regs[i-2].cpc_entry.reg, gas_t, sizeof(*gas_t));
		} else {
			pr_debug("Err in entry:%d in CPC table of CPU:%d \n", i, pr->id);
			goto out_free;
		}
	}
	per_cpu(cpu_pcc_subspace_idx, pr->id) = pcc_subspace_id;

	/*
	 * Initialize the remaining cpc_regs as unsupported.
	 * Example: In case FW exposes CPPC v2, the below loop will initialize
	 * LOWEST_FREQ and NOMINAL_FREQ regs as unsupported
	 */
	for (i = num_ent - 2; i < MAX_CPC_REG_ENT; i++) {
		cpc_ptr->cpc_regs[i].type = ACPI_TYPE_INTEGER;
		cpc_ptr->cpc_regs[i].cpc_entry.int_value = 0;
	}


	/* Store CPU Logical ID */
	cpc_ptr->cpu_id = pr->id;

	/* Parse PSD data for this CPU */
	ret = acpi_get_psd(cpc_ptr, handle);
	if (ret)
		goto out_free;

	/* Register PCC channel once for all PCC subspace ID. */
	if (pcc_subspace_id >= 0 && !pcc_data[pcc_subspace_id]->pcc_channel_acquired) {
		ret = register_pcc_channel(pcc_subspace_id);
		if (ret)
			goto out_free;

		init_rwsem(&pcc_data[pcc_subspace_id]->pcc_lock);
		init_waitqueue_head(&pcc_data[pcc_subspace_id]->pcc_write_wait_q);
	}

	/* Everything looks okay */
	pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);

	/* Add per logical CPU nodes for reading its feedback counters. */
	cpu_dev = get_cpu_device(pr->id);
	if (!cpu_dev) {
		ret = -EINVAL;
		goto out_free;
	}

	/* Plug PSD data into this CPU's CPC descriptor. */
	per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;

	ret = kobject_init_and_add(&cpc_ptr->kobj, &cppc_ktype, &cpu_dev->kobj,
			"acpi_cppc");
	if (ret) {
		per_cpu(cpc_desc_ptr, pr->id) = NULL;
		goto out_free;
	}

	kfree(output.pointer);
	return 0;

out_free:
	/* Free all the mapped sys mem areas for this CPU */
	for (i = 2; i < cpc_ptr->num_entries; i++) {
		void __iomem *addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;

		if (addr)
			iounmap(addr);
	}
	kfree(cpc_ptr);

out_buf_free:
	kfree(output.pointer);
	return ret;
}
EXPORT_SYMBOL_GPL(acpi_cppc_processor_probe);

/**
 * acpi_cppc_processor_exit - Cleanup CPC structs.
 * @pr: Ptr to acpi_processor containing this CPU's logical ID.
 *
 * Return: Void
 */
void acpi_cppc_processor_exit(struct acpi_processor *pr)
{
	struct cpc_desc *cpc_ptr;
	unsigned int i;
	void __iomem *addr;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, pr->id);

	if (pcc_ss_id >=0 && pcc_data[pcc_ss_id]) {
		if (pcc_data[pcc_ss_id]->pcc_channel_acquired) {
			pcc_data[pcc_ss_id]->refcount--;
			if (!pcc_data[pcc_ss_id]->refcount) {
				pcc_mbox_free_channel(pcc_data[pcc_ss_id]->pcc_channel);
				kfree(pcc_data[pcc_ss_id]);
				pcc_data[pcc_ss_id] = NULL;
			}
		}
	}

	cpc_ptr = per_cpu(cpc_desc_ptr, pr->id);
	if (!cpc_ptr)
		return;

	/* Free all the mapped sys mem areas for this CPU */
	for (i = 2; i < cpc_ptr->num_entries; i++) {
		addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;
		if (addr)
			iounmap(addr);
	}

	kobject_put(&cpc_ptr->kobj);
	kfree(cpc_ptr);
}
EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);

/**
 * cpc_read_ffh() - Read FFH register
 * @cpunum:	CPU number to read
 * @reg:	cppc register information
 * @val:	place holder for return value
 *
 * Read bit_width bits from a specified address and bit_offset
 *
 * Return: 0 for success and error code
 */
int __weak cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
{
	return -ENOTSUPP;
}

/**
 * cpc_write_ffh() - Write FFH register
 * @cpunum:	CPU number to write
 * @reg:	cppc register information
 * @val:	value to write
 *
 * Write value of bit_width bits to a specified address and bit_offset
 *
 * Return: 0 for success and error code
 */
int __weak cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
{
	return -ENOTSUPP;
}

/*
 * Since cpc_read and cpc_write are called while holding pcc_lock, it should be
 * as fast as possible. We have already mapped the PCC subspace during init, so
 * we can directly write to it.
 */

static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
{
	int ret_val = 0;
	void __iomem *vaddr = 0;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
	struct cpc_reg *reg = &reg_res->cpc_entry.reg;

	if (reg_res->type == ACPI_TYPE_INTEGER) {
		*val = reg_res->cpc_entry.int_value;
		return ret_val;
	}

	*val = 0;
	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
		vaddr = reg_res->sys_mem_vaddr;
	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
		return cpc_read_ffh(cpu, reg, val);
	else
		return acpi_os_read_memory((acpi_physical_address)reg->address,
				val, reg->bit_width);

	switch (reg->bit_width) {
		case 8:
			*val = readb_relaxed(vaddr);
			break;
		case 16:
			*val = readw_relaxed(vaddr);
			break;
		case 32:
			*val = readl_relaxed(vaddr);
			break;
		case 64:
			*val = readq_relaxed(vaddr);
			break;
		default:
			pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
				 reg->bit_width, pcc_ss_id);
			ret_val = -EFAULT;
	}

	return ret_val;
}

static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
{
	int ret_val = 0;
	void __iomem *vaddr = 0;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
	struct cpc_reg *reg = &reg_res->cpc_entry.reg;

	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
		vaddr = reg_res->sys_mem_vaddr;
	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
		return cpc_write_ffh(cpu, reg, val);
	else
		return acpi_os_write_memory((acpi_physical_address)reg->address,
				val, reg->bit_width);

	switch (reg->bit_width) {
		case 8:
			writeb_relaxed(val, vaddr);
			break;
		case 16:
			writew_relaxed(val, vaddr);
			break;
		case 32:
			writel_relaxed(val, vaddr);
			break;
		case 64:
			writeq_relaxed(val, vaddr);
			break;
		default:
			pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
				 reg->bit_width, pcc_ss_id);
			ret_val = -EFAULT;
			break;
	}

	return ret_val;
}

/**
 * cppc_get_desired_perf - Get the value of desired performance register.
 * @cpunum: CPU from which to get desired performance.
 * @desired_perf: address of a variable to store the returned desired performance
 *
 * Return: 0 for success, -EIO otherwise.
 */
int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
{
	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
	struct cpc_register_resource *desired_reg;
	struct cppc_pcc_data *pcc_ss_data = NULL;

	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];

	if (CPC_IN_PCC(desired_reg)) {
		int ret = 0;

		if (pcc_ss_id < 0)
			return -EIO;

		pcc_ss_data = pcc_data[pcc_ss_id];

		down_write(&pcc_ss_data->pcc_lock);

		if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
			cpc_read(cpunum, desired_reg, desired_perf);
		else
			ret = -EIO;

		up_write(&pcc_ss_data->pcc_lock);

		return ret;
	}

	cpc_read(cpunum, desired_reg, desired_perf);

	return 0;
}
EXPORT_SYMBOL_GPL(cppc_get_desired_perf);

/**
 * cppc_get_perf_caps - Get a CPU's performance capabilities.
 * @cpunum: CPU from which to get capabilities info.
 * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
 *
 * Return: 0 for success with perf_caps populated else -ERRNO.
 */
int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
{
	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
	struct cpc_register_resource *highest_reg, *lowest_reg,
		*lowest_non_linear_reg, *nominal_reg, *guaranteed_reg,
		*low_freq_reg = NULL, *nom_freq_reg = NULL;
	u64 high, low, guaranteed, nom, min_nonlinear, low_f = 0, nom_f = 0;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
	struct cppc_pcc_data *pcc_ss_data = NULL;
	int ret = 0, regs_in_pcc = 0;

	if (!cpc_desc) {
		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
		return -ENODEV;
	}

	highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
	lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
	lowest_non_linear_reg = &cpc_desc->cpc_regs[LOW_NON_LINEAR_PERF];
	nominal_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
	low_freq_reg = &cpc_desc->cpc_regs[LOWEST_FREQ];
	nom_freq_reg = &cpc_desc->cpc_regs[NOMINAL_FREQ];
	guaranteed_reg = &cpc_desc->cpc_regs[GUARANTEED_PERF];

	/* Are any of the regs PCC ?*/
	if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
		CPC_IN_PCC(lowest_non_linear_reg) || CPC_IN_PCC(nominal_reg) ||
		CPC_IN_PCC(low_freq_reg) || CPC_IN_PCC(nom_freq_reg)) {
		if (pcc_ss_id < 0) {
			pr_debug("Invalid pcc_ss_id\n");
			return -ENODEV;
		}
		pcc_ss_data = pcc_data[pcc_ss_id];
		regs_in_pcc = 1;
		down_write(&pcc_ss_data->pcc_lock);
		/* Ring doorbell once to update PCC subspace */
		if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
			ret = -EIO;
			goto out_err;
		}
	}

	cpc_read(cpunum, highest_reg, &high);
	perf_caps->highest_perf = high;

	cpc_read(cpunum, lowest_reg, &low);
	perf_caps->lowest_perf = low;

	cpc_read(cpunum, nominal_reg, &nom);
	perf_caps->nominal_perf = nom;

	if (guaranteed_reg->type != ACPI_TYPE_BUFFER  ||
	    IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) {
		perf_caps->guaranteed_perf = 0;
	} else {
		cpc_read(cpunum, guaranteed_reg, &guaranteed);
		perf_caps->guaranteed_perf = guaranteed;
	}

	cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
	perf_caps->lowest_nonlinear_perf = min_nonlinear;

	if (!high || !low || !nom || !min_nonlinear)
		ret = -EFAULT;

	/* Read optional lowest and nominal frequencies if present */
	if (CPC_SUPPORTED(low_freq_reg))
		cpc_read(cpunum, low_freq_reg, &low_f);

	if (CPC_SUPPORTED(nom_freq_reg))
		cpc_read(cpunum, nom_freq_reg, &nom_f);

	perf_caps->lowest_freq = low_f;
	perf_caps->nominal_freq = nom_f;


out_err:
	if (regs_in_pcc)
		up_write(&pcc_ss_data->pcc_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(cppc_get_perf_caps);

/**
 * cppc_get_perf_ctrs - Read a CPU's performance feedback counters.
 * @cpunum: CPU from which to read counters.
 * @perf_fb_ctrs: ptr to cppc_perf_fb_ctrs. See cppc_acpi.h
 *
 * Return: 0 for success with perf_fb_ctrs populated else -ERRNO.
 */
int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
{
	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
	struct cpc_register_resource *delivered_reg, *reference_reg,
		*ref_perf_reg, *ctr_wrap_reg;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
	struct cppc_pcc_data *pcc_ss_data = NULL;
	u64 delivered, reference, ref_perf, ctr_wrap_time;
	int ret = 0, regs_in_pcc = 0;

	if (!cpc_desc) {
		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
		return -ENODEV;
	}

	delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
	reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
	ref_perf_reg = &cpc_desc->cpc_regs[REFERENCE_PERF];
	ctr_wrap_reg = &cpc_desc->cpc_regs[CTR_WRAP_TIME];

	/*
	 * If reference perf register is not supported then we should
	 * use the nominal perf value
	 */
	if (!CPC_SUPPORTED(ref_perf_reg))
		ref_perf_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];

	/* Are any of the regs PCC ?*/
	if (CPC_IN_PCC(delivered_reg) || CPC_IN_PCC(reference_reg) ||
		CPC_IN_PCC(ctr_wrap_reg) || CPC_IN_PCC(ref_perf_reg)) {
		if (pcc_ss_id < 0) {
			pr_debug("Invalid pcc_ss_id\n");
			return -ENODEV;
		}
		pcc_ss_data = pcc_data[pcc_ss_id];
		down_write(&pcc_ss_data->pcc_lock);
		regs_in_pcc = 1;
		/* Ring doorbell once to update PCC subspace */
		if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
			ret = -EIO;
			goto out_err;
		}
	}

	cpc_read(cpunum, delivered_reg, &delivered);
	cpc_read(cpunum, reference_reg, &reference);
	cpc_read(cpunum, ref_perf_reg, &ref_perf);

	/*
	 * Per spec, if ctr_wrap_time optional register is unsupported, then the
	 * performance counters are assumed to never wrap during the lifetime of
	 * platform
	 */
	ctr_wrap_time = (u64)(~((u64)0));
	if (CPC_SUPPORTED(ctr_wrap_reg))
		cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);

	if (!delivered || !reference ||	!ref_perf) {
		ret = -EFAULT;
		goto out_err;
	}

	perf_fb_ctrs->delivered = delivered;
	perf_fb_ctrs->reference = reference;
	perf_fb_ctrs->reference_perf = ref_perf;
	perf_fb_ctrs->wraparound_time = ctr_wrap_time;
out_err:
	if (regs_in_pcc)
		up_write(&pcc_ss_data->pcc_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);

/**
 * cppc_set_perf - Set a CPU's performance controls.
 * @cpu: CPU for which to set performance controls.
 * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
 *
 * Return: 0 for success, -ERRNO otherwise.
 */
int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
{
	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
	struct cpc_register_resource *desired_reg;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
	struct cppc_pcc_data *pcc_ss_data = NULL;
	int ret = 0;

	if (!cpc_desc) {
		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
		return -ENODEV;
	}

	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];

	/*
	 * This is Phase-I where we want to write to CPC registers
	 * -> We want all CPUs to be able to execute this phase in parallel
	 *
	 * Since read_lock can be acquired by multiple CPUs simultaneously we
	 * achieve that goal here
	 */
	if (CPC_IN_PCC(desired_reg)) {
		if (pcc_ss_id < 0) {
			pr_debug("Invalid pcc_ss_id\n");
			return -ENODEV;
		}
		pcc_ss_data = pcc_data[pcc_ss_id];
		down_read(&pcc_ss_data->pcc_lock); /* BEGIN Phase-I */
		if (pcc_ss_data->platform_owns_pcc) {
			ret = check_pcc_chan(pcc_ss_id, false);
			if (ret) {
				up_read(&pcc_ss_data->pcc_lock);
				return ret;
			}
		}
		/*
		 * Update the pending_write to make sure a PCC CMD_READ will not
		 * arrive and steal the channel during the switch to write lock
		 */
		pcc_ss_data->pending_pcc_write_cmd = true;
		cpc_desc->write_cmd_id = pcc_ss_data->pcc_write_cnt;
		cpc_desc->write_cmd_status = 0;
	}

	/*
	 * Skip writing MIN/MAX until Linux knows how to come up with
	 * useful values.
	 */
	cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);

	if (CPC_IN_PCC(desired_reg))
		up_read(&pcc_ss_data->pcc_lock);	/* END Phase-I */
	/*
	 * This is Phase-II where we transfer the ownership of PCC to Platform
	 *
	 * Short Summary: Basically if we think of a group of cppc_set_perf
	 * requests that happened in short overlapping interval. The last CPU to
	 * come out of Phase-I will enter Phase-II and ring the doorbell.
	 *
	 * We have the following requirements for Phase-II:
	 *     1. We want to execute Phase-II only when there are no CPUs
	 * currently executing in Phase-I
	 *     2. Once we start Phase-II we want to avoid all other CPUs from
	 * entering Phase-I.
	 *     3. We want only one CPU among all those who went through Phase-I
	 * to run phase-II
	 *
	 * If write_trylock fails to get the lock and doesn't transfer the
	 * PCC ownership to the platform, then one of the following will be TRUE
	 *     1. There is at-least one CPU in Phase-I which will later execute
	 * write_trylock, so the CPUs in Phase-I will be responsible for
	 * executing the Phase-II.
	 *     2. Some other CPU has beaten this CPU to successfully execute the
	 * write_trylock and has already acquired the write_lock. We know for a
	 * fact it (other CPU acquiring the write_lock) couldn't have happened
	 * before this CPU's Phase-I as we held the read_lock.
	 *     3. Some other CPU executing pcc CMD_READ has stolen the
	 * down_write, in which case, send_pcc_cmd will check for pending
	 * CMD_WRITE commands by checking the pending_pcc_write_cmd.
	 * So this CPU can be certain that its request will be delivered
	 *    So in all cases, this CPU knows that its request will be delivered
	 * by another CPU and can return
	 *
	 * After getting the down_write we still need to check for
	 * pending_pcc_write_cmd to take care of the following scenario
	 *    The thread running this code could be scheduled out between
	 * Phase-I and Phase-II. Before it is scheduled back on, another CPU
	 * could have delivered the request to Platform by triggering the
	 * doorbell and transferred the ownership of PCC to platform. So this
	 * avoids triggering an unnecessary doorbell and more importantly before
	 * triggering the doorbell it makes sure that the PCC channel ownership
	 * is still with OSPM.
	 *   pending_pcc_write_cmd can also be cleared by a different CPU, if
	 * there was a pcc CMD_READ waiting on down_write and it steals the lock
	 * before the pcc CMD_WRITE is completed. pcc_send_cmd checks for this
	 * case during a CMD_READ and if there are pending writes it delivers
	 * the write command before servicing the read command
	 */
	if (CPC_IN_PCC(desired_reg)) {
		if (down_write_trylock(&pcc_ss_data->pcc_lock)) {/* BEGIN Phase-II */
			/* Update only if there are pending write commands */
			if (pcc_ss_data->pending_pcc_write_cmd)
				send_pcc_cmd(pcc_ss_id, CMD_WRITE);
			up_write(&pcc_ss_data->pcc_lock);	/* END Phase-II */
		} else
			/* Wait until pcc_write_cnt is updated by send_pcc_cmd */
			wait_event(pcc_ss_data->pcc_write_wait_q,
				   cpc_desc->write_cmd_id != pcc_ss_data->pcc_write_cnt);

		/* send_pcc_cmd updates the status in case of failure */
		ret = cpc_desc->write_cmd_status;
	}
	return ret;
}
EXPORT_SYMBOL_GPL(cppc_set_perf);

/**
 * cppc_get_transition_latency - returns frequency transition latency in ns
 *
 * ACPI CPPC does not explicitly specifiy how a platform can specify the
 * transition latency for perfromance change requests. The closest we have
 * is the timing information from the PCCT tables which provides the info
 * on the number and frequency of PCC commands the platform can handle.
 */
unsigned int cppc_get_transition_latency(int cpu_num)
{
	/*
	 * Expected transition latency is based on the PCCT timing values
	 * Below are definition from ACPI spec:
	 * pcc_nominal- Expected latency to process a command, in microseconds
	 * pcc_mpar   - The maximum number of periodic requests that the subspace
	 *              channel can support, reported in commands per minute. 0
	 *              indicates no limitation.
	 * pcc_mrtt   - The minimum amount of time that OSPM must wait after the
	 *              completion of a command before issuing the next command,
	 *              in microseconds.
	 */
	unsigned int latency_ns = 0;
	struct cpc_desc *cpc_desc;
	struct cpc_register_resource *desired_reg;
	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu_num);
	struct cppc_pcc_data *pcc_ss_data;

	cpc_desc = per_cpu(cpc_desc_ptr, cpu_num);
	if (!cpc_desc)
		return CPUFREQ_ETERNAL;

	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
	if (!CPC_IN_PCC(desired_reg))
		return CPUFREQ_ETERNAL;

	if (pcc_ss_id < 0)
		return CPUFREQ_ETERNAL;

	pcc_ss_data = pcc_data[pcc_ss_id];
	if (pcc_ss_data->pcc_mpar)
		latency_ns = 60 * (1000 * 1000 * 1000 / pcc_ss_data->pcc_mpar);

	latency_ns = max(latency_ns, pcc_ss_data->pcc_nominal * 1000);
	latency_ns = max(latency_ns, pcc_ss_data->pcc_mrtt * 1000);

	return latency_ns;
}
EXPORT_SYMBOL_GPL(cppc_get_transition_latency);