1 /* 2 * Copyright (C) 2014 Linaro Ltd. 3 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * PCC (Platform Communication Channel) is defined in the ACPI 5.0+ 16 * specification. It is a mailbox like mechanism to allow clients 17 * such as CPPC (Collaborative Processor Performance Control), RAS 18 * (Reliability, Availability and Serviceability) and MPST (Memory 19 * Node Power State Table) to talk to the platform (e.g. BMC) through 20 * shared memory regions as defined in the PCC table entries. The PCC 21 * specification supports a Doorbell mechanism for the PCC clients 22 * to notify the platform about new data. This Doorbell information 23 * is also specified in each PCC table entry. 24 * 25 * Typical high level flow of operation is: 26 * 27 * PCC Reads: 28 * * Client tries to acquire a channel lock. 29 * * After it is acquired it writes READ cmd in communication region cmd 30 * address. 31 * * Client issues mbox_send_message() which rings the PCC doorbell 32 * for its PCC channel. 33 * * If command completes, then client has control over channel and 34 * it can proceed with its reads. 35 * * Client releases lock. 36 * 37 * PCC Writes: 38 * * Client tries to acquire channel lock. 39 * * Client writes to its communication region after it acquires a 40 * channel lock. 41 * * Client writes WRITE cmd in communication region cmd address. 42 * * Client issues mbox_send_message() which rings the PCC doorbell 43 * for its PCC channel. 44 * * If command completes, then writes have succeded and it can release 45 * the channel lock. 46 * 47 * There is a Nominal latency defined for each channel which indicates 48 * how long to wait until a command completes. If command is not complete 49 * the client needs to retry or assume failure. 50 * 51 * For more details about PCC, please see the ACPI specification from 52 * http://www.uefi.org/ACPIv5.1 Section 14. 53 * 54 * This file implements PCC as a Mailbox controller and allows for PCC 55 * clients to be implemented as its Mailbox Client Channels. 56 */ 57 58 #include <linux/acpi.h> 59 #include <linux/delay.h> 60 #include <linux/io.h> 61 #include <linux/init.h> 62 #include <linux/interrupt.h> 63 #include <linux/list.h> 64 #include <linux/platform_device.h> 65 #include <linux/mailbox_controller.h> 66 #include <linux/mailbox_client.h> 67 #include <linux/io-64-nonatomic-lo-hi.h> 68 #include <acpi/pcc.h> 69 70 #include "mailbox.h" 71 72 #define MBOX_IRQ_NAME "pcc-mbox" 73 74 static struct mbox_chan *pcc_mbox_channels; 75 76 /* Array of cached virtual address for doorbell registers */ 77 static void __iomem **pcc_doorbell_vaddr; 78 /* Array of cached virtual address for doorbell ack registers */ 79 static void __iomem **pcc_doorbell_ack_vaddr; 80 /* Array of doorbell interrupts */ 81 static int *pcc_doorbell_irq; 82 83 static struct mbox_controller pcc_mbox_ctrl = {}; 84 /** 85 * get_pcc_channel - Given a PCC subspace idx, get 86 * the respective mbox_channel. 87 * @id: PCC subspace index. 88 * 89 * Return: ERR_PTR(errno) if error, else pointer 90 * to mbox channel. 91 */ 92 static struct mbox_chan *get_pcc_channel(int id) 93 { 94 if (id < 0 || id >= pcc_mbox_ctrl.num_chans) 95 return ERR_PTR(-ENOENT); 96 97 return &pcc_mbox_channels[id]; 98 } 99 100 /* 101 * PCC can be used with perf critical drivers such as CPPC 102 * So it makes sense to locally cache the virtual address and 103 * use it to read/write to PCC registers such as doorbell register 104 * 105 * The below read_register and write_registers are used to read and 106 * write from perf critical registers such as PCC doorbell register 107 */ 108 static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width) 109 { 110 int ret_val = 0; 111 112 switch (bit_width) { 113 case 8: 114 *val = readb(vaddr); 115 break; 116 case 16: 117 *val = readw(vaddr); 118 break; 119 case 32: 120 *val = readl(vaddr); 121 break; 122 case 64: 123 *val = readq(vaddr); 124 break; 125 default: 126 pr_debug("Error: Cannot read register of %u bit width", 127 bit_width); 128 ret_val = -EFAULT; 129 break; 130 } 131 return ret_val; 132 } 133 134 static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width) 135 { 136 int ret_val = 0; 137 138 switch (bit_width) { 139 case 8: 140 writeb(val, vaddr); 141 break; 142 case 16: 143 writew(val, vaddr); 144 break; 145 case 32: 146 writel(val, vaddr); 147 break; 148 case 64: 149 writeq(val, vaddr); 150 break; 151 default: 152 pr_debug("Error: Cannot write register of %u bit width", 153 bit_width); 154 ret_val = -EFAULT; 155 break; 156 } 157 return ret_val; 158 } 159 160 /** 161 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number 162 * @interrupt: GSI number. 163 * @flags: interrupt flags 164 * 165 * Returns: a valid linux IRQ number on success 166 * 0 or -EINVAL on failure 167 */ 168 static int pcc_map_interrupt(u32 interrupt, u32 flags) 169 { 170 int trigger, polarity; 171 172 if (!interrupt) 173 return 0; 174 175 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE 176 : ACPI_LEVEL_SENSITIVE; 177 178 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW 179 : ACPI_ACTIVE_HIGH; 180 181 return acpi_register_gsi(NULL, interrupt, trigger, polarity); 182 } 183 184 /** 185 * pcc_mbox_irq - PCC mailbox interrupt handler 186 */ 187 static irqreturn_t pcc_mbox_irq(int irq, void *p) 188 { 189 struct acpi_generic_address *doorbell_ack; 190 struct acpi_pcct_hw_reduced *pcct_ss; 191 struct mbox_chan *chan = p; 192 u64 doorbell_ack_preserve; 193 u64 doorbell_ack_write; 194 u64 doorbell_ack_val; 195 int ret; 196 197 pcct_ss = chan->con_priv; 198 199 mbox_chan_received_data(chan, NULL); 200 201 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { 202 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv; 203 u32 id = chan - pcc_mbox_channels; 204 205 doorbell_ack = &pcct2_ss->platform_ack_register; 206 doorbell_ack_preserve = pcct2_ss->ack_preserve_mask; 207 doorbell_ack_write = pcct2_ss->ack_write_mask; 208 209 ret = read_register(pcc_doorbell_ack_vaddr[id], 210 &doorbell_ack_val, 211 doorbell_ack->bit_width); 212 if (ret) 213 return IRQ_NONE; 214 215 ret = write_register(pcc_doorbell_ack_vaddr[id], 216 (doorbell_ack_val & doorbell_ack_preserve) 217 | doorbell_ack_write, 218 doorbell_ack->bit_width); 219 if (ret) 220 return IRQ_NONE; 221 } 222 223 return IRQ_HANDLED; 224 } 225 226 /** 227 * pcc_mbox_request_channel - PCC clients call this function to 228 * request a pointer to their PCC subspace, from which they 229 * can get the details of communicating with the remote. 230 * @cl: Pointer to Mailbox client, so we know where to bind the 231 * Channel. 232 * @subspace_id: The PCC Subspace index as parsed in the PCC client 233 * ACPI package. This is used to lookup the array of PCC 234 * subspaces as parsed by the PCC Mailbox controller. 235 * 236 * Return: Pointer to the Mailbox Channel if successful or 237 * ERR_PTR. 238 */ 239 struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, 240 int subspace_id) 241 { 242 struct device *dev = pcc_mbox_ctrl.dev; 243 struct mbox_chan *chan; 244 unsigned long flags; 245 246 /* 247 * Each PCC Subspace is a Mailbox Channel. 248 * The PCC Clients get their PCC Subspace ID 249 * from their own tables and pass it here. 250 * This returns a pointer to the PCC subspace 251 * for the Client to operate on. 252 */ 253 chan = get_pcc_channel(subspace_id); 254 255 if (IS_ERR(chan) || chan->cl) { 256 dev_err(dev, "Channel not found for idx: %d\n", subspace_id); 257 return ERR_PTR(-EBUSY); 258 } 259 260 spin_lock_irqsave(&chan->lock, flags); 261 chan->msg_free = 0; 262 chan->msg_count = 0; 263 chan->active_req = NULL; 264 chan->cl = cl; 265 init_completion(&chan->tx_complete); 266 267 if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) 268 chan->txdone_method = TXDONE_BY_ACK; 269 270 spin_unlock_irqrestore(&chan->lock, flags); 271 272 if (pcc_doorbell_irq[subspace_id] > 0) { 273 int rc; 274 275 rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id], 276 pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan); 277 if (unlikely(rc)) { 278 dev_err(dev, "failed to register PCC interrupt %d\n", 279 pcc_doorbell_irq[subspace_id]); 280 pcc_mbox_free_channel(chan); 281 chan = ERR_PTR(rc); 282 } 283 } 284 285 return chan; 286 } 287 EXPORT_SYMBOL_GPL(pcc_mbox_request_channel); 288 289 /** 290 * pcc_mbox_free_channel - Clients call this to free their Channel. 291 * 292 * @chan: Pointer to the mailbox channel as returned by 293 * pcc_mbox_request_channel() 294 */ 295 void pcc_mbox_free_channel(struct mbox_chan *chan) 296 { 297 u32 id = chan - pcc_mbox_channels; 298 unsigned long flags; 299 300 if (!chan || !chan->cl) 301 return; 302 303 if (id >= pcc_mbox_ctrl.num_chans) { 304 pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n"); 305 return; 306 } 307 308 if (pcc_doorbell_irq[id] > 0) 309 devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan); 310 311 spin_lock_irqsave(&chan->lock, flags); 312 chan->cl = NULL; 313 chan->active_req = NULL; 314 if (chan->txdone_method == TXDONE_BY_ACK) 315 chan->txdone_method = TXDONE_BY_POLL; 316 317 spin_unlock_irqrestore(&chan->lock, flags); 318 } 319 EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); 320 321 /** 322 * pcc_send_data - Called from Mailbox Controller code. Used 323 * here only to ring the channel doorbell. The PCC client 324 * specific read/write is done in the client driver in 325 * order to maintain atomicity over PCC channel once 326 * OS has control over it. See above for flow of operations. 327 * @chan: Pointer to Mailbox channel over which to send data. 328 * @data: Client specific data written over channel. Used here 329 * only for debug after PCC transaction completes. 330 * 331 * Return: Err if something failed else 0 for success. 332 */ 333 static int pcc_send_data(struct mbox_chan *chan, void *data) 334 { 335 struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv; 336 struct acpi_generic_address *doorbell; 337 u64 doorbell_preserve; 338 u64 doorbell_val; 339 u64 doorbell_write; 340 u32 id = chan - pcc_mbox_channels; 341 int ret = 0; 342 343 if (id >= pcc_mbox_ctrl.num_chans) { 344 pr_debug("pcc_send_data: Invalid mbox_chan passed\n"); 345 return -ENOENT; 346 } 347 348 doorbell = &pcct_ss->doorbell_register; 349 doorbell_preserve = pcct_ss->preserve_mask; 350 doorbell_write = pcct_ss->write_mask; 351 352 /* Sync notification from OS to Platform. */ 353 if (pcc_doorbell_vaddr[id]) { 354 ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val, 355 doorbell->bit_width); 356 if (ret) 357 return ret; 358 ret = write_register(pcc_doorbell_vaddr[id], 359 (doorbell_val & doorbell_preserve) | doorbell_write, 360 doorbell->bit_width); 361 } else { 362 ret = acpi_read(&doorbell_val, doorbell); 363 if (ret) 364 return ret; 365 ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, 366 doorbell); 367 } 368 return ret; 369 } 370 371 static const struct mbox_chan_ops pcc_chan_ops = { 372 .send_data = pcc_send_data, 373 }; 374 375 /** 376 * parse_pcc_subspaces -- Count PCC subspaces defined 377 * @header: Pointer to the ACPI subtable header under the PCCT. 378 * @end: End of subtable entry. 379 * 380 * Return: If we find a PCC subspace entry of a valid type, return 0. 381 * Otherwise, return -EINVAL. 382 * 383 * This gets called for each entry in the PCC table. 384 */ 385 static int parse_pcc_subspace(struct acpi_subtable_header *header, 386 const unsigned long end) 387 { 388 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header; 389 390 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED) 391 return 0; 392 393 return -EINVAL; 394 } 395 396 /** 397 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register 398 * There should be one entry per PCC client. 399 * @id: PCC subspace index. 400 * @pcct_ss: Pointer to the ACPI subtable header under the PCCT. 401 * 402 * Return: 0 for Success, else errno. 403 * 404 * This gets called for each entry in the PCC table. 405 */ 406 static int pcc_parse_subspace_irq(int id, 407 struct acpi_pcct_hw_reduced *pcct_ss) 408 { 409 pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->platform_interrupt, 410 (u32)pcct_ss->flags); 411 if (pcc_doorbell_irq[id] <= 0) { 412 pr_err("PCC GSI %d not registered\n", 413 pcct_ss->platform_interrupt); 414 return -EINVAL; 415 } 416 417 if (pcct_ss->header.type 418 == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { 419 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss; 420 421 pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap( 422 pcct2_ss->platform_ack_register.address, 423 pcct2_ss->platform_ack_register.bit_width / 8); 424 if (!pcc_doorbell_ack_vaddr[id]) { 425 pr_err("Failed to ioremap PCC ACK register\n"); 426 return -ENOMEM; 427 } 428 } 429 430 return 0; 431 } 432 433 /** 434 * acpi_pcc_probe - Parse the ACPI tree for the PCCT. 435 * 436 * Return: 0 for Success, else errno. 437 */ 438 static int __init acpi_pcc_probe(void) 439 { 440 struct acpi_table_header *pcct_tbl; 441 struct acpi_subtable_header *pcct_entry; 442 struct acpi_table_pcct *acpi_pcct_tbl; 443 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED]; 444 int count, i, rc; 445 acpi_status status = AE_OK; 446 447 /* Search for PCCT */ 448 status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl); 449 450 if (ACPI_FAILURE(status) || !pcct_tbl) 451 return -ENODEV; 452 453 /* Set up the subtable handlers */ 454 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE; 455 i < ACPI_PCCT_TYPE_RESERVED; i++) { 456 proc[i].id = i; 457 proc[i].count = 0; 458 proc[i].handler = parse_pcc_subspace; 459 } 460 461 count = acpi_table_parse_entries_array(ACPI_SIG_PCCT, 462 sizeof(struct acpi_table_pcct), proc, 463 ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES); 464 if (count == 0 || count > MAX_PCC_SUBSPACES) { 465 pr_warn("Invalid PCCT: %d PCC subspaces\n", count); 466 return -EINVAL; 467 } 468 469 pcc_mbox_channels = kcalloc(count, sizeof(struct mbox_chan), 470 GFP_KERNEL); 471 if (!pcc_mbox_channels) { 472 pr_err("Could not allocate space for PCC mbox channels\n"); 473 return -ENOMEM; 474 } 475 476 pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL); 477 if (!pcc_doorbell_vaddr) { 478 rc = -ENOMEM; 479 goto err_free_mbox; 480 } 481 482 pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL); 483 if (!pcc_doorbell_ack_vaddr) { 484 rc = -ENOMEM; 485 goto err_free_db_vaddr; 486 } 487 488 pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL); 489 if (!pcc_doorbell_irq) { 490 rc = -ENOMEM; 491 goto err_free_db_ack_vaddr; 492 } 493 494 /* Point to the first PCC subspace entry */ 495 pcct_entry = (struct acpi_subtable_header *) ( 496 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct)); 497 498 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl; 499 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL) 500 pcc_mbox_ctrl.txdone_irq = true; 501 502 for (i = 0; i < count; i++) { 503 struct acpi_generic_address *db_reg; 504 struct acpi_pcct_subspace *pcct_ss; 505 pcc_mbox_channels[i].con_priv = pcct_entry; 506 507 if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE || 508 pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) { 509 struct acpi_pcct_hw_reduced *pcct_hrss; 510 511 pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry; 512 513 if (pcc_mbox_ctrl.txdone_irq) { 514 rc = pcc_parse_subspace_irq(i, pcct_hrss); 515 if (rc < 0) 516 goto err; 517 } 518 } 519 pcct_ss = (struct acpi_pcct_subspace *) pcct_entry; 520 521 /* If doorbell is in system memory cache the virt address */ 522 db_reg = &pcct_ss->doorbell_register; 523 if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) 524 pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address, 525 db_reg->bit_width/8); 526 pcct_entry = (struct acpi_subtable_header *) 527 ((unsigned long) pcct_entry + pcct_entry->length); 528 } 529 530 pcc_mbox_ctrl.num_chans = count; 531 532 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans); 533 534 return 0; 535 536 err: 537 kfree(pcc_doorbell_irq); 538 err_free_db_ack_vaddr: 539 kfree(pcc_doorbell_ack_vaddr); 540 err_free_db_vaddr: 541 kfree(pcc_doorbell_vaddr); 542 err_free_mbox: 543 kfree(pcc_mbox_channels); 544 return rc; 545 } 546 547 /** 548 * pcc_mbox_probe - Called when we find a match for the 549 * PCCT platform device. This is purely used to represent 550 * the PCCT as a virtual device for registering with the 551 * generic Mailbox framework. 552 * 553 * @pdev: Pointer to platform device returned when a match 554 * is found. 555 * 556 * Return: 0 for Success, else errno. 557 */ 558 static int pcc_mbox_probe(struct platform_device *pdev) 559 { 560 int ret = 0; 561 562 pcc_mbox_ctrl.chans = pcc_mbox_channels; 563 pcc_mbox_ctrl.ops = &pcc_chan_ops; 564 pcc_mbox_ctrl.dev = &pdev->dev; 565 566 pr_info("Registering PCC driver as Mailbox controller\n"); 567 ret = mbox_controller_register(&pcc_mbox_ctrl); 568 569 if (ret) { 570 pr_err("Err registering PCC as Mailbox controller: %d\n", ret); 571 ret = -ENODEV; 572 } 573 574 return ret; 575 } 576 577 struct platform_driver pcc_mbox_driver = { 578 .probe = pcc_mbox_probe, 579 .driver = { 580 .name = "PCCT", 581 .owner = THIS_MODULE, 582 }, 583 }; 584 585 static int __init pcc_init(void) 586 { 587 int ret; 588 struct platform_device *pcc_pdev; 589 590 if (acpi_disabled) 591 return -ENODEV; 592 593 /* Check if PCC support is available. */ 594 ret = acpi_pcc_probe(); 595 596 if (ret) { 597 pr_debug("ACPI PCC probe failed.\n"); 598 return -ENODEV; 599 } 600 601 pcc_pdev = platform_create_bundle(&pcc_mbox_driver, 602 pcc_mbox_probe, NULL, 0, NULL, 0); 603 604 if (IS_ERR(pcc_pdev)) { 605 pr_debug("Err creating PCC platform bundle\n"); 606 return PTR_ERR(pcc_pdev); 607 } 608 609 return 0; 610 } 611 612 /* 613 * Make PCC init postcore so that users of this mailbox 614 * such as the ACPI Processor driver have it available 615 * at their init. 616 */ 617 postcore_initcall(pcc_init); 618