arch/powerpc/platforms/pseries/msi.c

   1 /*
   2  * Copyright 2006 Jake Moilanen <moilanen@austin.ibm.com>, IBM Corp.
   3  * Copyright 2006-2007 Michael Ellerman, IBM Corp.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; version 2 of the
   8  * License.
   9  *
  10  */
  11
  12 #include <linux/device.h>
  13 #include <linux/irq.h>
  14 #include <linux/msi.h>
  15
  16 #include <asm/rtas.h>
  17 #include <asm/hw_irq.h>
  18 #include <asm/ppc-pci.h>
  19
  20 static int query_token, change_token;
  21
  22 #define RTAS_QUERY_FN           0
  23 #define RTAS_CHANGE_FN          1
  24 #define RTAS_RESET_FN           2
  25 #define RTAS_CHANGE_MSI_FN      3
  26 #define RTAS_CHANGE_MSIX_FN     4
  27
  28 static struct pci_dn *get_pdn(struct pci_dev *pdev)
  29 {
  30         struct device_node *dn;
  31         struct pci_dn *pdn;
  32
  33         dn = pci_device_to_OF_node(pdev);
  34         if (!dn) {
  35                 dev_dbg(&pdev->dev, "rtas_msi: No OF device node\n");
  36                 return NULL;
  37         }
  38
  39         pdn = PCI_DN(dn);
  40         if (!pdn) {
  41                 dev_dbg(&pdev->dev, "rtas_msi: No PCI DN\n");
  42                 return NULL;
  43         }
  44
  45         return pdn;
  46 }
  47
  48 /* RTAS Helpers */
  49
  50 static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
  51 {
  52         u32 addr, seq_num, rtas_ret[3];
  53         unsigned long buid;
  54         int rc;
  55
  56         addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
  57         buid = pdn->phb->buid;
  58
  59         seq_num = 1;
  60         do {
  61                 if (func == RTAS_CHANGE_MSI_FN || func == RTAS_CHANGE_MSIX_FN)
  62                         rc = rtas_call(change_token, 6, 4, rtas_ret, addr,
  63                                         BUID_HI(buid), BUID_LO(buid),
  64                                         func, num_irqs, seq_num);
  65                 else
  66                         rc = rtas_call(change_token, 6, 3, rtas_ret, addr,
  67                                         BUID_HI(buid), BUID_LO(buid),
  68                                         func, num_irqs, seq_num);
  69
  70                 seq_num = rtas_ret[1];
  71         } while (rtas_busy_delay(rc));
  72
  73         /*
  74          * If the RTAS call succeeded, return the number of irqs allocated.
  75          * If not, make sure we return a negative error code.
  76          */
  77         if (rc == 0)
  78                 rc = rtas_ret[0];
  79         else if (rc > 0)
  80                 rc = -rc;
  81
  82         pr_debug("rtas_msi: ibm,change_msi(func=%d,num=%d), got %d rc = %d\n",
  83                  func, num_irqs, rtas_ret[0], rc);
  84
  85         return rc;
  86 }
  87
  88 static void rtas_disable_msi(struct pci_dev *pdev)
  89 {
  90         struct pci_dn *pdn;
  91
  92         pdn = get_pdn(pdev);
  93         if (!pdn)
  94                 return;
  95
  96         /*
  97          * disabling MSI with the explicit interface also disables MSI-X
  98          */
  99         if (rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, 0) != 0) {
 100                 /*
 101                  * may have failed because explicit interface is not
 102                  * present
 103                  */
 104                 if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0) != 0) {
 105                         pr_debug("rtas_msi: Setting MSIs to 0 failed!\n");
 106                 }
 107         }
 108 }
 109
 110 static int rtas_query_irq_number(struct pci_dn *pdn, int offset)
 111 {
 112         u32 addr, rtas_ret[2];
 113         unsigned long buid;
 114         int rc;
 115
 116         addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
 117         buid = pdn->phb->buid;
 118
 119         do {
 120                 rc = rtas_call(query_token, 4, 3, rtas_ret, addr,
 121                                BUID_HI(buid), BUID_LO(buid), offset);
 122         } while (rtas_busy_delay(rc));
 123
 124         if (rc) {
 125                 pr_debug("rtas_msi: error (%d) querying source number\n", rc);
 126                 return rc;
 127         }
 128
 129         return rtas_ret[0];
 130 }
 131
 132 static void rtas_teardown_msi_irqs(struct pci_dev *pdev)
 133 {
 134         struct msi_desc *entry;
 135
 136         list_for_each_entry(entry, &pdev->msi_list, list) {
 137                 if (entry->irq == NO_IRQ)
 138                         continue;
 139
 140                 irq_set_msi_desc(entry->irq, NULL);
 141                 irq_dispose_mapping(entry->irq);
 142         }
 143
 144         rtas_disable_msi(pdev);
 145 }
 146
 147 static int check_req(struct pci_dev *pdev, int nvec, char *prop_name)
 148 {
 149         struct device_node *dn;
 150         struct pci_dn *pdn;
 151         const u32 *req_msi;
 152
 153         pdn = get_pdn(pdev);
 154         if (!pdn)
 155                 return -ENODEV;
 156
 157         dn = pdn->node;
 158
 159         req_msi = of_get_property(dn, prop_name, NULL);
 160         if (!req_msi) {
 161                 pr_debug("rtas_msi: No %s on %s\n", prop_name, dn->full_name);
 162                 return -ENOENT;
 163         }
 164
 165         if (*req_msi < nvec) {
 166                 pr_debug("rtas_msi: %s requests < %d MSIs\n", prop_name, nvec);
 167
 168                 if (*req_msi == 0) /* Be paranoid */
 169                         return -ENOSPC;
 170
 171                 return *req_msi;
 172         }
 173
 174         return 0;
 175 }
 176
 177 static int check_req_msi(struct pci_dev *pdev, int nvec)
 178 {
 179         return check_req(pdev, nvec, "ibm,req#msi");
 180 }
 181
 182 static int check_req_msix(struct pci_dev *pdev, int nvec)
 183 {
 184         return check_req(pdev, nvec, "ibm,req#msi-x");
 185 }
 186
 187 /* Quota calculation */
 188
 189 static struct device_node *find_pe_total_msi(struct pci_dev *dev, int *total)
 190 {
 191         struct device_node *dn;
 192         const u32 *p;
 193
 194         dn = of_node_get(pci_device_to_OF_node(dev));
 195         while (dn) {
 196                 p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
 197                 if (p) {
 198                         pr_debug("rtas_msi: found prop on dn %s\n",
 199                                 dn->full_name);
 200                         *total = *p;
 201                         return dn;
 202                 }
 203
 204                 dn = of_get_next_parent(dn);
 205         }
 206
 207         return NULL;
 208 }
 209
 210 static struct device_node *find_pe_dn(struct pci_dev *dev, int *total)
 211 {
 212         struct device_node *dn;
 213
 214         /* Found our PE and assume 8 at that point. */
 215
 216         dn = pci_device_to_OF_node(dev);
 217         if (!dn)
 218                 return NULL;
 219
 220         dn = find_device_pe(dn);
 221         if (!dn)
 222                 return NULL;
 223
 224         /* We actually want the parent */
 225         dn = of_get_parent(dn);
 226         if (!dn)
 227                 return NULL;
 228
 229         /* Hardcode of 8 for old firmwares */
 230         *total = 8;
 231         pr_debug("rtas_msi: using PE dn %s\n", dn->full_name);
 232
 233         return dn;
 234 }
 235
 236 struct msi_counts {
 237         struct device_node *requestor;
 238         int num_devices;
 239         int request;
 240         int quota;
 241         int spare;
 242         int over_quota;
 243 };
 244
 245 static void *count_non_bridge_devices(struct device_node *dn, void *data)
 246 {
 247         struct msi_counts *counts = data;
 248         const u32 *p;
 249         u32 class;
 250
 251         pr_debug("rtas_msi: counting %s\n", dn->full_name);
 252
 253         p = of_get_property(dn, "class-code", NULL);
 254         class = p ? *p : 0;
 255
 256         if ((class >> 8) != PCI_CLASS_BRIDGE_PCI)
 257                 counts->num_devices++;
 258
 259         return NULL;
 260 }
 261
 262 static void *count_spare_msis(struct device_node *dn, void *data)
 263 {
 264         struct msi_counts *counts = data;
 265         const u32 *p;
 266         int req;
 267
 268         if (dn == counts->requestor)
 269                 req = counts->request;
 270         else {
 271                 /* We don't know if a driver will try to use MSI or MSI-X,
 272                  * so we just have to punt and use the larger of the two. */
 273                 req = 0;
 274                 p = of_get_property(dn, "ibm,req#msi", NULL);
 275                 if (p)
 276                         req = *p;
 277
 278                 p = of_get_property(dn, "ibm,req#msi-x", NULL);
 279                 if (p)
 280                         req = max(req, (int)*p);
 281         }
 282
 283         if (req < counts->quota)
 284                 counts->spare += counts->quota - req;
 285         else if (req > counts->quota)
 286                 counts->over_quota++;
 287
 288         return NULL;
 289 }
 290
 291 static int msi_quota_for_device(struct pci_dev *dev, int request)
 292 {
 293         struct device_node *pe_dn;
 294         struct msi_counts counts;
 295         int total;
 296
 297         pr_debug("rtas_msi: calc quota for %s, request %d\n", pci_name(dev),
 298                   request);
 299
 300         pe_dn = find_pe_total_msi(dev, &total);
 301         if (!pe_dn)
 302                 pe_dn = find_pe_dn(dev, &total);
 303
 304         if (!pe_dn) {
 305                 pr_err("rtas_msi: couldn't find PE for %s\n", pci_name(dev));
 306                 goto out;
 307         }
 308
 309         pr_debug("rtas_msi: found PE %s\n", pe_dn->full_name);
 310
 311         memset(&counts, 0, sizeof(struct msi_counts));
 312
 313         /* Work out how many devices we have below this PE */
 314         traverse_pci_devices(pe_dn, count_non_bridge_devices, &counts);
 315
 316         if (counts.num_devices == 0) {
 317                 pr_err("rtas_msi: found 0 devices under PE for %s\n",
 318                         pci_name(dev));
 319                 goto out;
 320         }
 321
 322         counts.quota = total / counts.num_devices;
 323         if (request <= counts.quota)
 324                 goto out;
 325
 326         /* else, we have some more calculating to do */
 327         counts.requestor = pci_device_to_OF_node(dev);
 328         counts.request = request;
 329         traverse_pci_devices(pe_dn, count_spare_msis, &counts);
 330
 331         /* If the quota isn't an integer multiple of the total, we can
 332          * use the remainder as spare MSIs for anyone that wants them. */
 333         counts.spare += total % counts.num_devices;
 334
 335         /* Divide any spare by the number of over-quota requestors */
 336         if (counts.over_quota)
 337                 counts.quota += counts.spare / counts.over_quota;
 338
 339         /* And finally clamp the request to the possibly adjusted quota */
 340         request = min(counts.quota, request);
 341
 342         pr_debug("rtas_msi: request clamped to quota %d\n", request);
 343 out:
 344         of_node_put(pe_dn);
 345
 346         return request;
 347 }
 348
 349 static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
 350 {
 351         int quota, rc;
 352
 353         if (type == PCI_CAP_ID_MSIX)
 354                 rc = check_req_msix(pdev, nvec);
 355         else
 356                 rc = check_req_msi(pdev, nvec);
 357
 358         if (rc)
 359                 return rc;
 360
 361         quota = msi_quota_for_device(pdev, nvec);
 362
 363         if (quota && quota < nvec)
 364                 return quota;
 365
 366         return 0;
 367 }
 368
 369 static int check_msix_entries(struct pci_dev *pdev)
 370 {
 371         struct msi_desc *entry;
 372         int expected;
 373
 374         /* There's no way for us to express to firmware that we want
 375          * a discontiguous, or non-zero based, range of MSI-X entries.
 376          * So we must reject such requests. */
 377
 378         expected = 0;
 379         list_for_each_entry(entry, &pdev->msi_list, list) {
 380                 if (entry->msi_attrib.entry_nr != expected) {
 381                         pr_debug("rtas_msi: bad MSI-X entries.\n");
 382                         return -EINVAL;
 383                 }
 384                 expected++;
 385         }
 386
 387         return 0;
 388 }
 389
 390 static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 391 {
 392         struct pci_dn *pdn;
 393         int hwirq, virq, i, rc;
 394         struct msi_desc *entry;
 395         struct msi_msg msg;
 396
 397         pdn = get_pdn(pdev);
 398         if (!pdn)
 399                 return -ENODEV;
 400
 401         if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
 402                 return -EINVAL;
 403
 404         /*
 405          * Try the new more explicit firmware interface, if that fails fall
 406          * back to the old interface. The old interface is known to never
 407          * return MSI-Xs.
 408          */
 409         if (type == PCI_CAP_ID_MSI) {
 410                 rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);
 411
 412                 if (rc < 0) {
 413                         pr_debug("rtas_msi: trying the old firmware call.\n");
 414                         rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
 415                 }
 416         } else
 417                 rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
 418
 419         if (rc != nvec) {
 420                 pr_debug("rtas_msi: rtas_change_msi() failed\n");
 421                 return rc;
 422         }
 423
 424         i = 0;
 425         list_for_each_entry(entry, &pdev->msi_list, list) {
 426                 hwirq = rtas_query_irq_number(pdn, i++);
 427                 if (hwirq < 0) {
 428                         pr_debug("rtas_msi: error (%d) getting hwirq\n", rc);
 429                         return hwirq;
 430                 }
 431
 432                 virq = irq_create_mapping(NULL, hwirq);
 433
 434                 if (virq == NO_IRQ) {
 435                         pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
 436                         return -ENOSPC;
 437                 }
 438
 439                 dev_dbg(&pdev->dev, "rtas_msi: allocated virq %d\n", virq);
 440                 irq_set_msi_desc(virq, entry);
 441
 442                 /* Read config space back so we can restore after reset */
 443                 read_msi_msg(virq, &msg);
 444                 entry->msg = msg;
 445         }
 446
 447         return 0;
 448 }
 449
 450 static void rtas_msi_pci_irq_fixup(struct pci_dev *pdev)
 451 {
 452         /* No LSI -> leave MSIs (if any) configured */
 453         if (pdev->irq == NO_IRQ) {
 454                 dev_dbg(&pdev->dev, "rtas_msi: no LSI, nothing to do.\n");
 455                 return;
 456         }
 457
 458         /* No MSI -> MSIs can't have been assigned by fw, leave LSI */
 459         if (check_req_msi(pdev, 1) && check_req_msix(pdev, 1)) {
 460                 dev_dbg(&pdev->dev, "rtas_msi: no req#msi/x, nothing to do.\n");
 461                 return;
 462         }
 463
 464         dev_dbg(&pdev->dev, "rtas_msi: disabling existing MSI.\n");
 465         rtas_disable_msi(pdev);
 466 }
 467
 468 static int rtas_msi_init(void)
 469 {
 470         query_token  = rtas_token("ibm,query-interrupt-source-number");
 471         change_token = rtas_token("ibm,change-msi");
 472
 473         if ((query_token == RTAS_UNKNOWN_SERVICE) ||
 474                         (change_token == RTAS_UNKNOWN_SERVICE)) {
 475                 pr_debug("rtas_msi: no RTAS tokens, no MSI support.\n");
 476                 return -1;
 477         }
 478
 479         pr_debug("rtas_msi: Registering RTAS MSI callbacks.\n");
 480
 481         WARN_ON(ppc_md.setup_msi_irqs);
 482         ppc_md.setup_msi_irqs = rtas_setup_msi_irqs;
 483         ppc_md.teardown_msi_irqs = rtas_teardown_msi_irqs;
 484         ppc_md.msi_check_device = rtas_msi_check_device;
 485
 486         WARN_ON(ppc_md.pci_irq_fixup);
 487         ppc_md.pci_irq_fixup = rtas_msi_pci_irq_fixup;
 488
 489         return 0;
 490 }
 491 arch_initcall(rtas_msi_init);