drivers/dma/ioat/dca.c

   1 /*
   2  * Intel I/OAT DMA Linux driver
   3  * Copyright(c) 2007 - 2009 Intel Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * The full GNU General Public License is included in this distribution in
  19  * the file called "COPYING".
  20  *
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/pci.h>
  25 #include <linux/smp.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/dca.h>
  28
  29 /* either a kernel change is needed, or we need something like this in kernel */
  30 #ifndef CONFIG_SMP
  31 #include <asm/smp.h>
  32 #undef cpu_physical_id
  33 #define cpu_physical_id(cpu) (cpuid_ebx(1) >> 24)
  34 #endif
  35
  36 #include "dma.h"
  37 #include "registers.h"
  38
  39 /*
  40  * Bit 7 of a tag map entry is the "valid" bit, if it is set then bits 0:6
  41  * contain the bit number of the APIC ID to map into the DCA tag.  If the valid
  42  * bit is not set, then the value must be 0 or 1 and defines the bit in the tag.
  43  */
  44 #define DCA_TAG_MAP_VALID 0x80
  45
  46 #define DCA3_TAG_MAP_BIT_TO_INV 0x80
  47 #define DCA3_TAG_MAP_BIT_TO_SEL 0x40
  48 #define DCA3_TAG_MAP_LITERAL_VAL 0x1
  49
  50 #define DCA_TAG_MAP_MASK 0xDF
  51
  52 /* expected tag map bytes for I/OAT ver.2 */
  53 #define DCA2_TAG_MAP_BYTE0 0x80
  54 #define DCA2_TAG_MAP_BYTE1 0x0
  55 #define DCA2_TAG_MAP_BYTE2 0x81
  56 #define DCA2_TAG_MAP_BYTE3 0x82
  57 #define DCA2_TAG_MAP_BYTE4 0x82
  58
  59 /* verify if tag map matches expected values */
  60 static inline int dca2_tag_map_valid(u8 *tag_map)
  61 {
  62         return ((tag_map[0] == DCA2_TAG_MAP_BYTE0) &&
  63                 (tag_map[1] == DCA2_TAG_MAP_BYTE1) &&
  64                 (tag_map[2] == DCA2_TAG_MAP_BYTE2) &&
  65                 (tag_map[3] == DCA2_TAG_MAP_BYTE3) &&
  66                 (tag_map[4] == DCA2_TAG_MAP_BYTE4));
  67 }
  68
  69 /*
  70  * "Legacy" DCA systems do not implement the DCA register set in the
  71  * I/OAT device.  Software needs direct support for their tag mappings.
  72  */
  73
  74 #define APICID_BIT(x)           (DCA_TAG_MAP_VALID | (x))
  75 #define IOAT_TAG_MAP_LEN        8
  76
  77 static u8 ioat_tag_map_BNB[IOAT_TAG_MAP_LEN] = {
  78         1, APICID_BIT(1), APICID_BIT(2), APICID_BIT(2), };
  79 static u8 ioat_tag_map_SCNB[IOAT_TAG_MAP_LEN] = {
  80         1, APICID_BIT(1), APICID_BIT(2), APICID_BIT(2), };
  81 static u8 ioat_tag_map_CNB[IOAT_TAG_MAP_LEN] = {
  82         1, APICID_BIT(1), APICID_BIT(3), APICID_BIT(4), APICID_BIT(2), };
  83 static u8 ioat_tag_map_UNISYS[IOAT_TAG_MAP_LEN] = { 0 };
  84
  85 /* pack PCI B/D/F into a u16 */
  86 static inline u16 dcaid_from_pcidev(struct pci_dev *pci)
  87 {
  88         return (pci->bus->number << 8) | pci->devfn;
  89 }
  90
  91 static int dca_enabled_in_bios(struct pci_dev *pdev)
  92 {
  93         /* CPUID level 9 returns DCA configuration */
  94         /* Bit 0 indicates DCA enabled by the BIOS */
  95         unsigned long cpuid_level_9;
  96         int res;
  97
  98         cpuid_level_9 = cpuid_eax(9);
  99         res = test_bit(0, &cpuid_level_9);
 100         if (!res)
 101                 dev_err(&pdev->dev, "DCA is disabled in BIOS\n");
 102
 103         return res;
 104 }
 105
 106 static int system_has_dca_enabled(struct pci_dev *pdev)
 107 {
 108         if (boot_cpu_has(X86_FEATURE_DCA))
 109                 return dca_enabled_in_bios(pdev);
 110
 111         dev_err(&pdev->dev, "boot cpu doesn't have X86_FEATURE_DCA\n");
 112         return 0;
 113 }
 114
 115 struct ioat_dca_slot {
 116         struct pci_dev *pdev;   /* requester device */
 117         u16 rid;                /* requester id, as used by IOAT */
 118 };
 119
 120 #define IOAT_DCA_MAX_REQ 6
 121 #define IOAT3_DCA_MAX_REQ 2
 122
 123 struct ioat_dca_priv {
 124         void __iomem            *iobase;
 125         void __iomem            *dca_base;
 126         int                      max_requesters;
 127         int                      requester_count;
 128         u8                       tag_map[IOAT_TAG_MAP_LEN];
 129         struct ioat_dca_slot     req_slots[0];
 130 };
 131
 132 /* 5000 series chipset DCA Port Requester ID Table Entry Format
 133  * [15:8]       PCI-Express Bus Number
 134  * [7:3]        PCI-Express Device Number
 135  * [2:0]        PCI-Express Function Number
 136  *
 137  * 5000 series chipset DCA control register format
 138  * [7:1]        Reserved (0)
 139  * [0]          Ignore Function Number
 140  */
 141
 142 static int ioat_dca_add_requester(struct dca_provider *dca, struct device *dev)
 143 {
 144         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 145         struct pci_dev *pdev;
 146         int i;
 147         u16 id;
 148
 149         /* This implementation only supports PCI-Express */
 150         if (dev->bus != &pci_bus_type)
 151                 return -ENODEV;
 152         pdev = to_pci_dev(dev);
 153         id = dcaid_from_pcidev(pdev);
 154
 155         if (ioatdca->requester_count == ioatdca->max_requesters)
 156                 return -ENODEV;
 157
 158         for (i = 0; i < ioatdca->max_requesters; i++) {
 159                 if (ioatdca->req_slots[i].pdev == NULL) {
 160                         /* found an empty slot */
 161                         ioatdca->requester_count++;
 162                         ioatdca->req_slots[i].pdev = pdev;
 163                         ioatdca->req_slots[i].rid = id;
 164                         writew(id, ioatdca->dca_base + (i * 4));
 165                         /* make sure the ignore function bit is off */
 166                         writeb(0, ioatdca->dca_base + (i * 4) + 2);
 167                         return i;
 168                 }
 169         }
 170         /* Error, ioatdma->requester_count is out of whack */
 171         return -EFAULT;
 172 }
 173
 174 static int ioat_dca_remove_requester(struct dca_provider *dca,
 175                                      struct device *dev)
 176 {
 177         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 178         struct pci_dev *pdev;
 179         int i;
 180
 181         /* This implementation only supports PCI-Express */
 182         if (dev->bus != &pci_bus_type)
 183                 return -ENODEV;
 184         pdev = to_pci_dev(dev);
 185
 186         for (i = 0; i < ioatdca->max_requesters; i++) {
 187                 if (ioatdca->req_slots[i].pdev == pdev) {
 188                         writew(0, ioatdca->dca_base + (i * 4));
 189                         ioatdca->req_slots[i].pdev = NULL;
 190                         ioatdca->req_slots[i].rid = 0;
 191                         ioatdca->requester_count--;
 192                         return i;
 193                 }
 194         }
 195         return -ENODEV;
 196 }
 197
 198 static u8 ioat_dca_get_tag(struct dca_provider *dca,
 199                            struct device *dev,
 200                            int cpu)
 201 {
 202         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 203         int i, apic_id, bit, value;
 204         u8 entry, tag;
 205
 206         tag = 0;
 207         apic_id = cpu_physical_id(cpu);
 208
 209         for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
 210                 entry = ioatdca->tag_map[i];
 211                 if (entry & DCA_TAG_MAP_VALID) {
 212                         bit = entry & ~DCA_TAG_MAP_VALID;
 213                         value = (apic_id & (1 << bit)) ? 1 : 0;
 214                 } else {
 215                         value = entry ? 1 : 0;
 216                 }
 217                 tag |= (value << i);
 218         }
 219         return tag;
 220 }
 221
 222 static int ioat_dca_dev_managed(struct dca_provider *dca,
 223                                 struct device *dev)
 224 {
 225         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 226         struct pci_dev *pdev;
 227         int i;
 228
 229         pdev = to_pci_dev(dev);
 230         for (i = 0; i < ioatdca->max_requesters; i++) {
 231                 if (ioatdca->req_slots[i].pdev == pdev)
 232                         return 1;
 233         }
 234         return 0;
 235 }
 236
 237 static struct dca_ops ioat_dca_ops = {
 238         .add_requester          = ioat_dca_add_requester,
 239         .remove_requester       = ioat_dca_remove_requester,
 240         .get_tag                = ioat_dca_get_tag,
 241         .dev_managed            = ioat_dca_dev_managed,
 242 };
 243
 244
 245 struct dca_provider * __devinit
 246 ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 247 {
 248         struct dca_provider *dca;
 249         struct ioat_dca_priv *ioatdca;
 250         u8 *tag_map = NULL;
 251         int i;
 252         int err;
 253         u8 version;
 254         u8 max_requesters;
 255
 256         if (!system_has_dca_enabled(pdev))
 257                 return NULL;
 258
 259         /* I/OAT v1 systems must have a known tag_map to support DCA */
 260         switch (pdev->vendor) {
 261         case PCI_VENDOR_ID_INTEL:
 262                 switch (pdev->device) {
 263                 case PCI_DEVICE_ID_INTEL_IOAT:
 264                         tag_map = ioat_tag_map_BNB;
 265                         break;
 266                 case PCI_DEVICE_ID_INTEL_IOAT_CNB:
 267                         tag_map = ioat_tag_map_CNB;
 268                         break;
 269                 case PCI_DEVICE_ID_INTEL_IOAT_SCNB:
 270                         tag_map = ioat_tag_map_SCNB;
 271                         break;
 272                 }
 273                 break;
 274         case PCI_VENDOR_ID_UNISYS:
 275                 switch (pdev->device) {
 276                 case PCI_DEVICE_ID_UNISYS_DMA_DIRECTOR:
 277                         tag_map = ioat_tag_map_UNISYS;
 278                         break;
 279                 }
 280                 break;
 281         }
 282         if (tag_map == NULL)
 283                 return NULL;
 284
 285         version = readb(iobase + IOAT_VER_OFFSET);
 286         if (version == IOAT_VER_3_0)
 287                 max_requesters = IOAT3_DCA_MAX_REQ;
 288         else
 289                 max_requesters = IOAT_DCA_MAX_REQ;
 290
 291         dca = alloc_dca_provider(&ioat_dca_ops,
 292                         sizeof(*ioatdca) +
 293                         (sizeof(struct ioat_dca_slot) * max_requesters));
 294         if (!dca)
 295                 return NULL;
 296
 297         ioatdca = dca_priv(dca);
 298         ioatdca->max_requesters = max_requesters;
 299         ioatdca->dca_base = iobase + 0x54;
 300
 301         /* copy over the APIC ID to DCA tag mapping */
 302         for (i = 0; i < IOAT_TAG_MAP_LEN; i++)
 303                 ioatdca->tag_map[i] = tag_map[i];
 304
 305         err = register_dca_provider(dca, &pdev->dev);
 306         if (err) {
 307                 free_dca_provider(dca);
 308                 return NULL;
 309         }
 310
 311         return dca;
 312 }
 313
 314
 315 static int ioat2_dca_add_requester(struct dca_provider *dca, struct device *dev)
 316 {
 317         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 318         struct pci_dev *pdev;
 319         int i;
 320         u16 id;
 321         u16 global_req_table;
 322
 323         /* This implementation only supports PCI-Express */
 324         if (dev->bus != &pci_bus_type)
 325                 return -ENODEV;
 326         pdev = to_pci_dev(dev);
 327         id = dcaid_from_pcidev(pdev);
 328
 329         if (ioatdca->requester_count == ioatdca->max_requesters)
 330                 return -ENODEV;
 331
 332         for (i = 0; i < ioatdca->max_requesters; i++) {
 333                 if (ioatdca->req_slots[i].pdev == NULL) {
 334                         /* found an empty slot */
 335                         ioatdca->requester_count++;
 336                         ioatdca->req_slots[i].pdev = pdev;
 337                         ioatdca->req_slots[i].rid = id;
 338                         global_req_table =
 339                               readw(ioatdca->dca_base + IOAT_DCA_GREQID_OFFSET);
 340                         writel(id | IOAT_DCA_GREQID_VALID,
 341                                ioatdca->iobase + global_req_table + (i * 4));
 342                         return i;
 343                 }
 344         }
 345         /* Error, ioatdma->requester_count is out of whack */
 346         return -EFAULT;
 347 }
 348
 349 static int ioat2_dca_remove_requester(struct dca_provider *dca,
 350                                       struct device *dev)
 351 {
 352         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 353         struct pci_dev *pdev;
 354         int i;
 355         u16 global_req_table;
 356
 357         /* This implementation only supports PCI-Express */
 358         if (dev->bus != &pci_bus_type)
 359                 return -ENODEV;
 360         pdev = to_pci_dev(dev);
 361
 362         for (i = 0; i < ioatdca->max_requesters; i++) {
 363                 if (ioatdca->req_slots[i].pdev == pdev) {
 364                         global_req_table =
 365                               readw(ioatdca->dca_base + IOAT_DCA_GREQID_OFFSET);
 366                         writel(0, ioatdca->iobase + global_req_table + (i * 4));
 367                         ioatdca->req_slots[i].pdev = NULL;
 368                         ioatdca->req_slots[i].rid = 0;
 369                         ioatdca->requester_count--;
 370                         return i;
 371                 }
 372         }
 373         return -ENODEV;
 374 }
 375
 376 static u8 ioat2_dca_get_tag(struct dca_provider *dca,
 377                             struct device *dev,
 378                             int cpu)
 379 {
 380         u8 tag;
 381
 382         tag = ioat_dca_get_tag(dca, dev, cpu);
 383         tag = (~tag) & 0x1F;
 384         return tag;
 385 }
 386
 387 static struct dca_ops ioat2_dca_ops = {
 388         .add_requester          = ioat2_dca_add_requester,
 389         .remove_requester       = ioat2_dca_remove_requester,
 390         .get_tag                = ioat2_dca_get_tag,
 391         .dev_managed            = ioat_dca_dev_managed,
 392 };
 393
 394 static int ioat2_dca_count_dca_slots(void __iomem *iobase, u16 dca_offset)
 395 {
 396         int slots = 0;
 397         u32 req;
 398         u16 global_req_table;
 399
 400         global_req_table = readw(iobase + dca_offset + IOAT_DCA_GREQID_OFFSET);
 401         if (global_req_table == 0)
 402                 return 0;
 403         do {
 404                 req = readl(iobase + global_req_table + (slots * sizeof(u32)));
 405                 slots++;
 406         } while ((req & IOAT_DCA_GREQID_LASTID) == 0);
 407
 408         return slots;
 409 }
 410
 411 struct dca_provider * __devinit
 412 ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 413 {
 414         struct dca_provider *dca;
 415         struct ioat_dca_priv *ioatdca;
 416         int slots;
 417         int i;
 418         int err;
 419         u32 tag_map;
 420         u16 dca_offset;
 421         u16 csi_fsb_control;
 422         u16 pcie_control;
 423         u8 bit;
 424
 425         if (!system_has_dca_enabled(pdev))
 426                 return NULL;
 427
 428         dca_offset = readw(iobase + IOAT_DCAOFFSET_OFFSET);
 429         if (dca_offset == 0)
 430                 return NULL;
 431
 432         slots = ioat2_dca_count_dca_slots(iobase, dca_offset);
 433         if (slots == 0)
 434                 return NULL;
 435
 436         dca = alloc_dca_provider(&ioat2_dca_ops,
 437                                  sizeof(*ioatdca)
 438                                       + (sizeof(struct ioat_dca_slot) * slots));
 439         if (!dca)
 440                 return NULL;
 441
 442         ioatdca = dca_priv(dca);
 443         ioatdca->iobase = iobase;
 444         ioatdca->dca_base = iobase + dca_offset;
 445         ioatdca->max_requesters = slots;
 446
 447         /* some bios might not know to turn these on */
 448         csi_fsb_control = readw(ioatdca->dca_base + IOAT_FSB_CAP_ENABLE_OFFSET);
 449         if ((csi_fsb_control & IOAT_FSB_CAP_ENABLE_PREFETCH) == 0) {
 450                 csi_fsb_control |= IOAT_FSB_CAP_ENABLE_PREFETCH;
 451                 writew(csi_fsb_control,
 452                        ioatdca->dca_base + IOAT_FSB_CAP_ENABLE_OFFSET);
 453         }
 454         pcie_control = readw(ioatdca->dca_base + IOAT_PCI_CAP_ENABLE_OFFSET);
 455         if ((pcie_control & IOAT_PCI_CAP_ENABLE_MEMWR) == 0) {
 456                 pcie_control |= IOAT_PCI_CAP_ENABLE_MEMWR;
 457                 writew(pcie_control,
 458                        ioatdca->dca_base + IOAT_PCI_CAP_ENABLE_OFFSET);
 459         }
 460
 461
 462         /* TODO version, compatibility and configuration checks */
 463
 464         /* copy out the APIC to DCA tag map */
 465         tag_map = readl(ioatdca->dca_base + IOAT_APICID_TAG_MAP_OFFSET);
 466         for (i = 0; i < 5; i++) {
 467                 bit = (tag_map >> (4 * i)) & 0x0f;
 468                 if (bit < 8)
 469                         ioatdca->tag_map[i] = bit | DCA_TAG_MAP_VALID;
 470                 else
 471                         ioatdca->tag_map[i] = 0;
 472         }
 473
 474         if (!dca2_tag_map_valid(ioatdca->tag_map)) {
 475                 dev_err(&pdev->dev, "APICID_TAG_MAP set incorrectly by BIOS, "
 476                         "disabling DCA\n");
 477                 free_dca_provider(dca);
 478                 return NULL;
 479         }
 480
 481         err = register_dca_provider(dca, &pdev->dev);
 482         if (err) {
 483                 free_dca_provider(dca);
 484                 return NULL;
 485         }
 486
 487         return dca;
 488 }
 489
 490 static int ioat3_dca_add_requester(struct dca_provider *dca, struct device *dev)
 491 {
 492         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 493         struct pci_dev *pdev;
 494         int i;
 495         u16 id;
 496         u16 global_req_table;
 497
 498         /* This implementation only supports PCI-Express */
 499         if (dev->bus != &pci_bus_type)
 500                 return -ENODEV;
 501         pdev = to_pci_dev(dev);
 502         id = dcaid_from_pcidev(pdev);
 503
 504         if (ioatdca->requester_count == ioatdca->max_requesters)
 505                 return -ENODEV;
 506
 507         for (i = 0; i < ioatdca->max_requesters; i++) {
 508                 if (ioatdca->req_slots[i].pdev == NULL) {
 509                         /* found an empty slot */
 510                         ioatdca->requester_count++;
 511                         ioatdca->req_slots[i].pdev = pdev;
 512                         ioatdca->req_slots[i].rid = id;
 513                         global_req_table =
 514                               readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
 515                         writel(id | IOAT_DCA_GREQID_VALID,
 516                                ioatdca->iobase + global_req_table + (i * 4));
 517                         return i;
 518                 }
 519         }
 520         /* Error, ioatdma->requester_count is out of whack */
 521         return -EFAULT;
 522 }
 523
 524 static int ioat3_dca_remove_requester(struct dca_provider *dca,
 525                                       struct device *dev)
 526 {
 527         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 528         struct pci_dev *pdev;
 529         int i;
 530         u16 global_req_table;
 531
 532         /* This implementation only supports PCI-Express */
 533         if (dev->bus != &pci_bus_type)
 534                 return -ENODEV;
 535         pdev = to_pci_dev(dev);
 536
 537         for (i = 0; i < ioatdca->max_requesters; i++) {
 538                 if (ioatdca->req_slots[i].pdev == pdev) {
 539                         global_req_table =
 540                               readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
 541                         writel(0, ioatdca->iobase + global_req_table + (i * 4));
 542                         ioatdca->req_slots[i].pdev = NULL;
 543                         ioatdca->req_slots[i].rid = 0;
 544                         ioatdca->requester_count--;
 545                         return i;
 546                 }
 547         }
 548         return -ENODEV;
 549 }
 550
 551 static u8 ioat3_dca_get_tag(struct dca_provider *dca,
 552                             struct device *dev,
 553                             int cpu)
 554 {
 555         u8 tag;
 556
 557         struct ioat_dca_priv *ioatdca = dca_priv(dca);
 558         int i, apic_id, bit, value;
 559         u8 entry;
 560
 561         tag = 0;
 562         apic_id = cpu_physical_id(cpu);
 563
 564         for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
 565                 entry = ioatdca->tag_map[i];
 566                 if (entry & DCA3_TAG_MAP_BIT_TO_SEL) {
 567                         bit = entry &
 568                                 ~(DCA3_TAG_MAP_BIT_TO_SEL | DCA3_TAG_MAP_BIT_TO_INV);
 569                         value = (apic_id & (1 << bit)) ? 1 : 0;
 570                 } else if (entry & DCA3_TAG_MAP_BIT_TO_INV) {
 571                         bit = entry & ~DCA3_TAG_MAP_BIT_TO_INV;
 572                         value = (apic_id & (1 << bit)) ? 0 : 1;
 573                 } else {
 574                         value = (entry & DCA3_TAG_MAP_LITERAL_VAL) ? 1 : 0;
 575                 }
 576                 tag |= (value << i);
 577         }
 578
 579         return tag;
 580 }
 581
 582 static struct dca_ops ioat3_dca_ops = {
 583         .add_requester          = ioat3_dca_add_requester,
 584         .remove_requester       = ioat3_dca_remove_requester,
 585         .get_tag                = ioat3_dca_get_tag,
 586         .dev_managed            = ioat_dca_dev_managed,
 587 };
 588
 589 static int ioat3_dca_count_dca_slots(void *iobase, u16 dca_offset)
 590 {
 591         int slots = 0;
 592         u32 req;
 593         u16 global_req_table;
 594
 595         global_req_table = readw(iobase + dca_offset + IOAT3_DCA_GREQID_OFFSET);
 596         if (global_req_table == 0)
 597                 return 0;
 598
 599         do {
 600                 req = readl(iobase + global_req_table + (slots * sizeof(u32)));
 601                 slots++;
 602         } while ((req & IOAT_DCA_GREQID_LASTID) == 0);
 603
 604         return slots;
 605 }
 606
 607 struct dca_provider * __devinit
 608 ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 609 {
 610         struct dca_provider *dca;
 611         struct ioat_dca_priv *ioatdca;
 612         int slots;
 613         int i;
 614         int err;
 615         u16 dca_offset;
 616         u16 csi_fsb_control;
 617         u16 pcie_control;
 618         u8 bit;
 619
 620         union {
 621                 u64 full;
 622                 struct {
 623                         u32 low;
 624                         u32 high;
 625                 };
 626         } tag_map;
 627
 628         if (!system_has_dca_enabled(pdev))
 629                 return NULL;
 630
 631         dca_offset = readw(iobase + IOAT_DCAOFFSET_OFFSET);
 632         if (dca_offset == 0)
 633                 return NULL;
 634
 635         slots = ioat3_dca_count_dca_slots(iobase, dca_offset);
 636         if (slots == 0)
 637                 return NULL;
 638
 639         dca = alloc_dca_provider(&ioat3_dca_ops,
 640                                  sizeof(*ioatdca)
 641                                       + (sizeof(struct ioat_dca_slot) * slots));
 642         if (!dca)
 643                 return NULL;
 644
 645         ioatdca = dca_priv(dca);
 646         ioatdca->iobase = iobase;
 647         ioatdca->dca_base = iobase + dca_offset;
 648         ioatdca->max_requesters = slots;
 649
 650         /* some bios might not know to turn these on */
 651         csi_fsb_control = readw(ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
 652         if ((csi_fsb_control & IOAT3_CSI_CONTROL_PREFETCH) == 0) {
 653                 csi_fsb_control |= IOAT3_CSI_CONTROL_PREFETCH;
 654                 writew(csi_fsb_control,
 655                        ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
 656         }
 657         pcie_control = readw(ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
 658         if ((pcie_control & IOAT3_PCI_CONTROL_MEMWR) == 0) {
 659                 pcie_control |= IOAT3_PCI_CONTROL_MEMWR;
 660                 writew(pcie_control,
 661                        ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
 662         }
 663
 664
 665         /* TODO version, compatibility and configuration checks */
 666
 667         /* copy out the APIC to DCA tag map */
 668         tag_map.low =
 669                 readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_LOW);
 670         tag_map.high =
 671                 readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_HIGH);
 672         for (i = 0; i < 8; i++) {
 673                 bit = tag_map.full >> (8 * i);
 674                 ioatdca->tag_map[i] = bit & DCA_TAG_MAP_MASK;
 675         }
 676
 677         err = register_dca_provider(dca, &pdev->dev);
 678         if (err) {
 679                 free_dca_provider(dca);
 680                 return NULL;
 681         }
 682
 683         return dca;
 684 }