hw/ppc/spapr_vio.c

   1 /*
   2  * QEMU sPAPR VIO code
   3  *
   4  * Copyright (c) 2010 David Gibson, IBM Corporation <dwg@au1.ibm.com>
   5  * Based on the s390 virtio bus code:
   6  * Copyright (c) 2009 Alexander Graf <agraf@suse.de>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "qemu/osdep.h"
  23 #include "qemu/error-report.h"
  24 #include "qapi/error.h"
  25 #include "hw/hw.h"
  26 #include "qemu/log.h"
  27 #include "sysemu/sysemu.h"
  28 #include "hw/boards.h"
  29 #include "hw/loader.h"
  30 #include "elf.h"
  31 #include "hw/sysbus.h"
  32 #include "sysemu/kvm.h"
  33 #include "sysemu/device_tree.h"
  34 #include "kvm_ppc.h"
  35
  36 #include "hw/ppc/spapr.h"
  37 #include "hw/ppc/spapr_vio.h"
  38 #include "hw/ppc/xics.h"
  39
  40 #include <libfdt.h>
  41
  42 /* #define DEBUG_SPAPR */
  43
  44 #ifdef DEBUG_SPAPR
  45 #define DPRINTF(fmt, ...) \
  46     do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
  47 #else
  48 #define DPRINTF(fmt, ...) \
  49     do { } while (0)
  50 #endif
  51
  52 static Property spapr_vio_props[] = {
  53     DEFINE_PROP_UINT32("irq", VIOsPAPRDevice, irq, 0), \
  54     DEFINE_PROP_END_OF_LIST(),
  55 };
  56
  57 static char *spapr_vio_get_dev_name(DeviceState *qdev)
  58 {
  59     VIOsPAPRDevice *dev = VIO_SPAPR_DEVICE(qdev);
  60     VIOsPAPRDeviceClass *pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
  61
  62     /* Device tree style name device@reg */
  63     return g_strdup_printf("%s@%x", pc->dt_name, dev->reg);
  64 }
  65
  66 static void spapr_vio_bus_class_init(ObjectClass *klass, void *data)
  67 {
  68     BusClass *k = BUS_CLASS(klass);
  69
  70     k->get_dev_path = spapr_vio_get_dev_name;
  71     k->get_fw_dev_path = spapr_vio_get_dev_name;
  72 }
  73
  74 static const TypeInfo spapr_vio_bus_info = {
  75     .name = TYPE_SPAPR_VIO_BUS,
  76     .parent = TYPE_BUS,
  77     .class_init = spapr_vio_bus_class_init,
  78     .instance_size = sizeof(VIOsPAPRBus),
  79 };
  80
  81 VIOsPAPRDevice *spapr_vio_find_by_reg(VIOsPAPRBus *bus, uint32_t reg)
  82 {
  83     BusChild *kid;
  84     VIOsPAPRDevice *dev = NULL;
  85
  86     QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
  87         dev = (VIOsPAPRDevice *)kid->child;
  88         if (dev->reg == reg) {
  89             return dev;
  90         }
  91     }
  92
  93     return NULL;
  94 }
  95
  96 static int vio_make_devnode(VIOsPAPRDevice *dev,
  97                             void *fdt)
  98 {
  99     VIOsPAPRDeviceClass *pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
 100     int vdevice_off, node_off, ret;
 101     char *dt_name;
 102
 103     vdevice_off = fdt_path_offset(fdt, "/vdevice");
 104     if (vdevice_off < 0) {
 105         return vdevice_off;
 106     }
 107
 108     dt_name = spapr_vio_get_dev_name(DEVICE(dev));
 109     node_off = fdt_add_subnode(fdt, vdevice_off, dt_name);
 110     g_free(dt_name);
 111     if (node_off < 0) {
 112         return node_off;
 113     }
 114
 115     ret = fdt_setprop_cell(fdt, node_off, "reg", dev->reg);
 116     if (ret < 0) {
 117         return ret;
 118     }
 119
 120     if (pc->dt_type) {
 121         ret = fdt_setprop_string(fdt, node_off, "device_type",
 122                                  pc->dt_type);
 123         if (ret < 0) {
 124             return ret;
 125         }
 126     }
 127
 128     if (pc->dt_compatible) {
 129         ret = fdt_setprop_string(fdt, node_off, "compatible",
 130                                  pc->dt_compatible);
 131         if (ret < 0) {
 132             return ret;
 133         }
 134     }
 135
 136     if (dev->irq) {
 137         uint32_t ints_prop[] = {cpu_to_be32(dev->irq), 0};
 138
 139         ret = fdt_setprop(fdt, node_off, "interrupts", ints_prop,
 140                           sizeof(ints_prop));
 141         if (ret < 0) {
 142             return ret;
 143         }
 144     }
 145
 146     ret = spapr_tcet_dma_dt(fdt, node_off, "ibm,my-dma-window", dev->tcet);
 147     if (ret < 0) {
 148         return ret;
 149     }
 150
 151     if (pc->devnode) {
 152         ret = (pc->devnode)(dev, fdt, node_off);
 153         if (ret < 0) {
 154             return ret;
 155         }
 156     }
 157
 158     return node_off;
 159 }
 160
 161 /*
 162  * CRQ handling
 163  */
 164 static target_ulong h_reg_crq(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 165                               target_ulong opcode, target_ulong *args)
 166 {
 167     target_ulong reg = args[0];
 168     target_ulong queue_addr = args[1];
 169     target_ulong queue_len = args[2];
 170     VIOsPAPRDevice *dev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
 171
 172     if (!dev) {
 173         hcall_dprintf("Unit 0x" TARGET_FMT_lx " does not exist\n", reg);
 174         return H_PARAMETER;
 175     }
 176
 177     /* We can't grok a queue size bigger than 256M for now */
 178     if (queue_len < 0x1000 || queue_len > 0x10000000) {
 179         hcall_dprintf("Queue size too small or too big (0x" TARGET_FMT_lx
 180                       ")\n", queue_len);
 181         return H_PARAMETER;
 182     }
 183
 184     /* Check queue alignment */
 185     if (queue_addr & 0xfff) {
 186         hcall_dprintf("Queue not aligned (0x" TARGET_FMT_lx ")\n", queue_addr);
 187         return H_PARAMETER;
 188     }
 189
 190     /* Check if device supports CRQs */
 191     if (!dev->crq.SendFunc) {
 192         hcall_dprintf("Device does not support CRQ\n");
 193         return H_NOT_FOUND;
 194     }
 195
 196     /* Already a queue ? */
 197     if (dev->crq.qsize) {
 198         hcall_dprintf("CRQ already registered\n");
 199         return H_RESOURCE;
 200     }
 201     dev->crq.qladdr = queue_addr;
 202     dev->crq.qsize = queue_len;
 203     dev->crq.qnext = 0;
 204
 205     DPRINTF("CRQ for dev 0x" TARGET_FMT_lx " registered at 0x"
 206             TARGET_FMT_lx "/0x" TARGET_FMT_lx "\n",
 207             reg, queue_addr, queue_len);
 208     return H_SUCCESS;
 209 }
 210
 211 static target_ulong free_crq(VIOsPAPRDevice *dev)
 212 {
 213     dev->crq.qladdr = 0;
 214     dev->crq.qsize = 0;
 215     dev->crq.qnext = 0;
 216
 217     DPRINTF("CRQ for dev 0x%" PRIx32 " freed\n", dev->reg);
 218
 219     return H_SUCCESS;
 220 }
 221
 222 static target_ulong h_free_crq(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 223                                target_ulong opcode, target_ulong *args)
 224 {
 225     target_ulong reg = args[0];
 226     VIOsPAPRDevice *dev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
 227
 228     if (!dev) {
 229         hcall_dprintf("Unit 0x" TARGET_FMT_lx " does not exist\n", reg);
 230         return H_PARAMETER;
 231     }
 232
 233     return free_crq(dev);
 234 }
 235
 236 static target_ulong h_send_crq(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 237                                target_ulong opcode, target_ulong *args)
 238 {
 239     target_ulong reg = args[0];
 240     target_ulong msg_hi = args[1];
 241     target_ulong msg_lo = args[2];
 242     VIOsPAPRDevice *dev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
 243     uint64_t crq_mangle[2];
 244
 245     if (!dev) {
 246         hcall_dprintf("Unit 0x" TARGET_FMT_lx " does not exist\n", reg);
 247         return H_PARAMETER;
 248     }
 249     crq_mangle[0] = cpu_to_be64(msg_hi);
 250     crq_mangle[1] = cpu_to_be64(msg_lo);
 251
 252     if (dev->crq.SendFunc) {
 253         return dev->crq.SendFunc(dev, (uint8_t *)crq_mangle);
 254     }
 255
 256     return H_HARDWARE;
 257 }
 258
 259 static target_ulong h_enable_crq(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 260                                  target_ulong opcode, target_ulong *args)
 261 {
 262     target_ulong reg = args[0];
 263     VIOsPAPRDevice *dev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
 264
 265     if (!dev) {
 266         hcall_dprintf("Unit 0x" TARGET_FMT_lx " does not exist\n", reg);
 267         return H_PARAMETER;
 268     }
 269
 270     return 0;
 271 }
 272
 273 /* Returns negative error, 0 success, or positive: queue full */
 274 int spapr_vio_send_crq(VIOsPAPRDevice *dev, uint8_t *crq)
 275 {
 276     int rc;
 277     uint8_t byte;
 278
 279     if (!dev->crq.qsize) {
 280         error_report("spapr_vio_send_creq on uninitialized queue");
 281         return -1;
 282     }
 283
 284     /* Maybe do a fast path for KVM just writing to the pages */
 285     rc = spapr_vio_dma_read(dev, dev->crq.qladdr + dev->crq.qnext, &byte, 1);
 286     if (rc) {
 287         return rc;
 288     }
 289     if (byte != 0) {
 290         return 1;
 291     }
 292
 293     rc = spapr_vio_dma_write(dev, dev->crq.qladdr + dev->crq.qnext + 8,
 294                              &crq[8], 8);
 295     if (rc) {
 296         return rc;
 297     }
 298
 299     kvmppc_eieio();
 300
 301     rc = spapr_vio_dma_write(dev, dev->crq.qladdr + dev->crq.qnext, crq, 8);
 302     if (rc) {
 303         return rc;
 304     }
 305
 306     dev->crq.qnext = (dev->crq.qnext + 16) % dev->crq.qsize;
 307
 308     if (dev->signal_state & 1) {
 309         qemu_irq_pulse(spapr_vio_qirq(dev));
 310     }
 311
 312     return 0;
 313 }
 314
 315 /* "quiesce" handling */
 316
 317 static void spapr_vio_quiesce_one(VIOsPAPRDevice *dev)
 318 {
 319     if (dev->tcet) {
 320         device_reset(DEVICE(dev->tcet));
 321     }
 322     free_crq(dev);
 323 }
 324
 325 void spapr_vio_set_bypass(VIOsPAPRDevice *dev, bool bypass)
 326 {
 327     if (!dev->tcet) {
 328         return;
 329     }
 330
 331     memory_region_set_enabled(&dev->mrbypass, bypass);
 332     memory_region_set_enabled(spapr_tce_get_iommu(dev->tcet), !bypass);
 333
 334     dev->tcet->bypass = bypass;
 335 }
 336
 337 static void rtas_set_tce_bypass(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 338                                 uint32_t token,
 339                                 uint32_t nargs, target_ulong args,
 340                                 uint32_t nret, target_ulong rets)
 341 {
 342     VIOsPAPRBus *bus = spapr->vio_bus;
 343     VIOsPAPRDevice *dev;
 344     uint32_t unit, enable;
 345
 346     if (nargs != 2) {
 347         rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 348         return;
 349     }
 350     unit = rtas_ld(args, 0);
 351     enable = rtas_ld(args, 1);
 352     dev = spapr_vio_find_by_reg(bus, unit);
 353     if (!dev) {
 354         rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 355         return;
 356     }
 357
 358     if (!dev->tcet) {
 359         rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 360         return;
 361     }
 362
 363     spapr_vio_set_bypass(dev, !!enable);
 364
 365     rtas_st(rets, 0, RTAS_OUT_SUCCESS);
 366 }
 367
 368 static void rtas_quiesce(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 369                          uint32_t token,
 370                          uint32_t nargs, target_ulong args,
 371                          uint32_t nret, target_ulong rets)
 372 {
 373     VIOsPAPRBus *bus = spapr->vio_bus;
 374     BusChild *kid;
 375     VIOsPAPRDevice *dev = NULL;
 376
 377     if (nargs != 0) {
 378         rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 379         return;
 380     }
 381
 382     QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
 383         dev = (VIOsPAPRDevice *)kid->child;
 384         spapr_vio_quiesce_one(dev);
 385     }
 386
 387     rtas_st(rets, 0, RTAS_OUT_SUCCESS);
 388 }
 389
 390 static VIOsPAPRDevice *reg_conflict(VIOsPAPRDevice *dev)
 391 {
 392     VIOsPAPRBus *bus = SPAPR_VIO_BUS(dev->qdev.parent_bus);
 393     BusChild *kid;
 394     VIOsPAPRDevice *other;
 395
 396     /*
 397      * Check for a device other than the given one which is already
 398      * using the requested address. We have to open code this because
 399      * the given dev might already be in the list.
 400      */
 401     QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
 402         other = VIO_SPAPR_DEVICE(kid->child);
 403
 404         if (other != dev && other->reg == dev->reg) {
 405             return other;
 406         }
 407     }
 408
 409     return 0;
 410 }
 411
 412 static void spapr_vio_busdev_reset(DeviceState *qdev)
 413 {
 414     VIOsPAPRDevice *dev = VIO_SPAPR_DEVICE(qdev);
 415     VIOsPAPRDeviceClass *pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
 416
 417     /* Shut down the request queue and TCEs if necessary */
 418     spapr_vio_quiesce_one(dev);
 419
 420     dev->signal_state = 0;
 421
 422     spapr_vio_set_bypass(dev, false);
 423     if (pc->reset) {
 424         pc->reset(dev);
 425     }
 426 }
 427
 428 static void spapr_vio_busdev_realize(DeviceState *qdev, Error **errp)
 429 {
 430     sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
 431     VIOsPAPRDevice *dev = (VIOsPAPRDevice *)qdev;
 432     VIOsPAPRDeviceClass *pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
 433     char *id;
 434     Error *local_err = NULL;
 435
 436     if (dev->reg != -1) {
 437         /*
 438          * Explicitly assigned address, just verify that no-one else
 439          * is using it.  other mechanism). We have to open code this
 440          * rather than using spapr_vio_find_by_reg() because sdev
 441          * itself is already in the list.
 442          */
 443         VIOsPAPRDevice *other = reg_conflict(dev);
 444
 445         if (other) {
 446             error_setg(errp, "%s and %s devices conflict at address %#x",
 447                        object_get_typename(OBJECT(qdev)),
 448                        object_get_typename(OBJECT(&other->qdev)),
 449                        dev->reg);
 450             return;
 451         }
 452     } else {
 453         /* Need to assign an address */
 454         VIOsPAPRBus *bus = SPAPR_VIO_BUS(dev->qdev.parent_bus);
 455
 456         do {
 457             dev->reg = bus->next_reg++;
 458         } while (reg_conflict(dev));
 459     }
 460
 461     /* Don't overwrite ids assigned on the command line */
 462     if (!dev->qdev.id) {
 463         id = spapr_vio_get_dev_name(DEVICE(dev));
 464         dev->qdev.id = id;
 465     }
 466
 467     dev->irq = xics_spapr_alloc(spapr->xics, 0, dev->irq, false, &local_err);
 468     if (local_err) {
 469         error_propagate(errp, local_err);
 470         return;
 471     }
 472
 473     if (pc->rtce_window_size) {
 474         uint32_t liobn = SPAPR_VIO_LIOBN(dev->reg);
 475
 476         memory_region_init(&dev->mrroot, OBJECT(dev), "iommu-spapr-root",
 477                            ram_size);
 478         memory_region_init_alias(&dev->mrbypass, OBJECT(dev),
 479                                  "iommu-spapr-bypass", get_system_memory(),
 480                                  0, ram_size);
 481         memory_region_add_subregion_overlap(&dev->mrroot, 0, &dev->mrbypass, 1);
 482         address_space_init(&dev->as, &dev->mrroot, qdev->id);
 483
 484         dev->tcet = spapr_tce_new_table(qdev, liobn);
 485         spapr_tce_table_enable(dev->tcet, SPAPR_TCE_PAGE_SHIFT, 0,
 486                                pc->rtce_window_size >> SPAPR_TCE_PAGE_SHIFT);
 487         dev->tcet->vdev = dev;
 488         memory_region_add_subregion_overlap(&dev->mrroot, 0,
 489                                             spapr_tce_get_iommu(dev->tcet), 2);
 490     }
 491
 492     pc->realize(dev, errp);
 493 }
 494
 495 static target_ulong h_vio_signal(PowerPCCPU *cpu, sPAPRMachineState *spapr,
 496                                  target_ulong opcode,
 497                                  target_ulong *args)
 498 {
 499     target_ulong reg = args[0];
 500     target_ulong mode = args[1];
 501     VIOsPAPRDevice *dev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
 502     VIOsPAPRDeviceClass *pc;
 503
 504     if (!dev) {
 505         return H_PARAMETER;
 506     }
 507
 508     pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
 509
 510     if (mode & ~pc->signal_mask) {
 511         return H_PARAMETER;
 512     }
 513
 514     dev->signal_state = mode;
 515
 516     return H_SUCCESS;
 517 }
 518
 519 VIOsPAPRBus *spapr_vio_bus_init(void)
 520 {
 521     VIOsPAPRBus *bus;
 522     BusState *qbus;
 523     DeviceState *dev;
 524
 525     /* Create bridge device */
 526     dev = qdev_create(NULL, TYPE_SPAPR_VIO_BRIDGE);
 527     qdev_init_nofail(dev);
 528
 529     /* Create bus on bridge device */
 530     qbus = qbus_create(TYPE_SPAPR_VIO_BUS, dev, "spapr-vio");
 531     bus = SPAPR_VIO_BUS(qbus);
 532     bus->next_reg = 0x71000000;
 533
 534     /* hcall-vio */
 535     spapr_register_hypercall(H_VIO_SIGNAL, h_vio_signal);
 536
 537     /* hcall-crq */
 538     spapr_register_hypercall(H_REG_CRQ, h_reg_crq);
 539     spapr_register_hypercall(H_FREE_CRQ, h_free_crq);
 540     spapr_register_hypercall(H_SEND_CRQ, h_send_crq);
 541     spapr_register_hypercall(H_ENABLE_CRQ, h_enable_crq);
 542
 543     /* RTAS calls */
 544     spapr_rtas_register(RTAS_IBM_SET_TCE_BYPASS, "ibm,set-tce-bypass",
 545                         rtas_set_tce_bypass);
 546     spapr_rtas_register(RTAS_QUIESCE, "quiesce", rtas_quiesce);
 547
 548     return bus;
 549 }
 550
 551 /* Represents sPAPR hcall VIO devices */
 552
 553 static int spapr_vio_bridge_init(SysBusDevice *dev)
 554 {
 555     /* nothing */
 556     return 0;
 557 }
 558
 559 static void spapr_vio_bridge_class_init(ObjectClass *klass, void *data)
 560 {
 561     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 562     DeviceClass *dc = DEVICE_CLASS(klass);
 563
 564     dc->fw_name = "vdevice";
 565     k->init = spapr_vio_bridge_init;
 566 }
 567
 568 static const TypeInfo spapr_vio_bridge_info = {
 569     .name          = TYPE_SPAPR_VIO_BRIDGE,
 570     .parent        = TYPE_SYS_BUS_DEVICE,
 571     .class_init    = spapr_vio_bridge_class_init,
 572 };
 573
 574 const VMStateDescription vmstate_spapr_vio = {
 575     .name = "spapr_vio",
 576     .version_id = 1,
 577     .minimum_version_id = 1,
 578     .fields = (VMStateField[]) {
 579         /* Sanity check */
 580         VMSTATE_UINT32_EQUAL(reg, VIOsPAPRDevice),
 581         VMSTATE_UINT32_EQUAL(irq, VIOsPAPRDevice),
 582
 583         /* General VIO device state */
 584         VMSTATE_UINT64(signal_state, VIOsPAPRDevice),
 585         VMSTATE_UINT64(crq.qladdr, VIOsPAPRDevice),
 586         VMSTATE_UINT32(crq.qsize, VIOsPAPRDevice),
 587         VMSTATE_UINT32(crq.qnext, VIOsPAPRDevice),
 588
 589         VMSTATE_END_OF_LIST()
 590     },
 591 };
 592
 593 static void vio_spapr_device_class_init(ObjectClass *klass, void *data)
 594 {
 595     DeviceClass *k = DEVICE_CLASS(klass);
 596     k->realize = spapr_vio_busdev_realize;
 597     k->reset = spapr_vio_busdev_reset;
 598     k->bus_type = TYPE_SPAPR_VIO_BUS;
 599     k->props = spapr_vio_props;
 600 }
 601
 602 static const TypeInfo spapr_vio_type_info = {
 603     .name = TYPE_VIO_SPAPR_DEVICE,
 604     .parent = TYPE_DEVICE,
 605     .instance_size = sizeof(VIOsPAPRDevice),
 606     .abstract = true,
 607     .class_size = sizeof(VIOsPAPRDeviceClass),
 608     .class_init = vio_spapr_device_class_init,
 609 };
 610
 611 static void spapr_vio_register_types(void)
 612 {
 613     type_register_static(&spapr_vio_bus_info);
 614     type_register_static(&spapr_vio_bridge_info);
 615     type_register_static(&spapr_vio_type_info);
 616 }
 617
 618 type_init(spapr_vio_register_types)
 619
 620 static int compare_reg(const void *p1, const void *p2)
 621 {
 622     VIOsPAPRDevice const *dev1, *dev2;
 623
 624     dev1 = (VIOsPAPRDevice *)*(DeviceState **)p1;
 625     dev2 = (VIOsPAPRDevice *)*(DeviceState **)p2;
 626
 627     if (dev1->reg < dev2->reg) {
 628         return -1;
 629     }
 630     if (dev1->reg == dev2->reg) {
 631         return 0;
 632     }
 633
 634     /* dev1->reg > dev2->reg */
 635     return 1;
 636 }
 637
 638 int spapr_populate_vdevice(VIOsPAPRBus *bus, void *fdt)
 639 {
 640     DeviceState *qdev, **qdevs;
 641     BusChild *kid;
 642     int i, num, ret = 0;
 643
 644     /* Count qdevs on the bus list */
 645     num = 0;
 646     QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
 647         num++;
 648     }
 649
 650     /* Copy out into an array of pointers */
 651     qdevs = g_malloc(sizeof(qdev) * num);
 652     num = 0;
 653     QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
 654         qdevs[num++] = kid->child;
 655     }
 656
 657     /* Sort the array */
 658     qsort(qdevs, num, sizeof(qdev), compare_reg);
 659
 660     /* Hack alert. Give the devices to libfdt in reverse order, we happen
 661      * to know that will mean they are in forward order in the tree. */
 662     for (i = num - 1; i >= 0; i--) {
 663         VIOsPAPRDevice *dev = (VIOsPAPRDevice *)(qdevs[i]);
 664
 665         ret = vio_make_devnode(dev, fdt);
 666
 667         if (ret < 0) {
 668             goto out;
 669         }
 670     }
 671
 672     ret = 0;
 673 out:
 674     g_free(qdevs);
 675
 676     return ret;
 677 }
 678
 679 int spapr_populate_chosen_stdout(void *fdt, VIOsPAPRBus *bus)
 680 {
 681     VIOsPAPRDevice *dev;
 682     char *name, *path;
 683     int ret, offset;
 684
 685     dev = spapr_vty_get_default(bus);
 686     if (!dev)
 687         return 0;
 688
 689     offset = fdt_path_offset(fdt, "/chosen");
 690     if (offset < 0) {
 691         return offset;
 692     }
 693
 694     name = spapr_vio_get_dev_name(DEVICE(dev));
 695     path = g_strdup_printf("/vdevice/%s", name);
 696
 697     ret = fdt_setprop_string(fdt, offset, "linux,stdout-path", path);
 698
 699     g_free(name);
 700     g_free(path);
 701
 702     return ret;
 703 }