qemu/hw/misc/bcm2835_mbox.c
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   1/*
   2 * Raspberry Pi emulation (c) 2012 Gregory Estrade
   3 * This code is licensed under the GNU GPLv2 and later.
   4 *
   5 * This file models the system mailboxes, which are used for
   6 * communication with low-bandwidth GPU peripherals. Refs:
   7 *   https://github.com/raspberrypi/firmware/wiki/Mailboxes
   8 *   https://github.com/raspberrypi/firmware/wiki/Accessing-mailboxes
   9 */
  10
  11#include "qemu/osdep.h"
  12#include "qapi/error.h"
  13#include "hw/irq.h"
  14#include "hw/misc/bcm2835_mbox.h"
  15#include "migration/vmstate.h"
  16#include "qemu/log.h"
  17#include "qemu/module.h"
  18#include "trace.h"
  19
  20#define MAIL0_PEEK   0x90
  21#define MAIL0_SENDER 0x94
  22#define MAIL1_STATUS 0xb8
  23
  24/* Mailbox status register */
  25#define MAIL0_STATUS 0x98
  26#define ARM_MS_FULL       0x80000000
  27#define ARM_MS_EMPTY      0x40000000
  28#define ARM_MS_LEVEL      0x400000FF /* Max. value depends on mailbox depth */
  29
  30/* MAILBOX config/status register */
  31#define MAIL0_CONFIG 0x9c
  32/* ANY write to this register clears the error bits! */
  33#define ARM_MC_IHAVEDATAIRQEN    0x00000001 /* mbox irq enable:  has data */
  34#define ARM_MC_IHAVESPACEIRQEN   0x00000002 /* mbox irq enable:  has space */
  35#define ARM_MC_OPPISEMPTYIRQEN   0x00000004 /* mbox irq enable: Opp is empty */
  36#define ARM_MC_MAIL_CLEAR        0x00000008 /* mbox clear write 1, then  0 */
  37#define ARM_MC_IHAVEDATAIRQPEND  0x00000010 /* mbox irq pending:  has space */
  38#define ARM_MC_IHAVESPACEIRQPEND 0x00000020 /* mbox irq pending: Opp is empty */
  39#define ARM_MC_OPPISEMPTYIRQPEND 0x00000040 /* mbox irq pending */
  40/* Bit 7 is unused */
  41#define ARM_MC_ERRNOOWN   0x00000100 /* error : none owner read from mailbox */
  42#define ARM_MC_ERROVERFLW 0x00000200 /* error : write to fill mailbox */
  43#define ARM_MC_ERRUNDRFLW 0x00000400 /* error : read from empty mailbox */
  44
  45static void mbox_update_status(BCM2835Mbox *mb)
  46{
  47    mb->status &= ~(ARM_MS_EMPTY | ARM_MS_FULL);
  48    if (mb->count == 0) {
  49        mb->status |= ARM_MS_EMPTY;
  50    } else if (mb->count == MBOX_SIZE) {
  51        mb->status |= ARM_MS_FULL;
  52    }
  53}
  54
  55static void mbox_reset(BCM2835Mbox *mb)
  56{
  57    int n;
  58
  59    mb->count = 0;
  60    mb->config = 0;
  61    for (n = 0; n < MBOX_SIZE; n++) {
  62        mb->reg[n] = MBOX_INVALID_DATA;
  63    }
  64    mbox_update_status(mb);
  65}
  66
  67static uint32_t mbox_pull(BCM2835Mbox *mb, int index)
  68{
  69    int n;
  70    uint32_t val;
  71
  72    assert(mb->count > 0);
  73    assert(index < mb->count);
  74
  75    val = mb->reg[index];
  76    for (n = index + 1; n < mb->count; n++) {
  77        mb->reg[n - 1] = mb->reg[n];
  78    }
  79    mb->count--;
  80    mb->reg[mb->count] = MBOX_INVALID_DATA;
  81
  82    mbox_update_status(mb);
  83
  84    return val;
  85}
  86
  87static void mbox_push(BCM2835Mbox *mb, uint32_t val)
  88{
  89    assert(mb->count < MBOX_SIZE);
  90    mb->reg[mb->count++] = val;
  91    mbox_update_status(mb);
  92}
  93
  94static void bcm2835_mbox_update(BCM2835MboxState *s)
  95{
  96    uint32_t value;
  97    bool set;
  98    int n;
  99
 100    s->mbox_irq_disabled = true;
 101
 102    /* Get pending responses and put them in the vc->arm mbox,
 103     * as long as it's not full
 104     */
 105    for (n = 0; n < MBOX_CHAN_COUNT; n++) {
 106        while (s->available[n] && !(s->mbox[0].status & ARM_MS_FULL)) {
 107            value = ldl_le_phys(&s->mbox_as, n << MBOX_AS_CHAN_SHIFT);
 108            assert(value != MBOX_INVALID_DATA); /* Pending interrupt but no data */
 109            mbox_push(&s->mbox[0], value);
 110        }
 111    }
 112
 113    /* TODO (?): Try to push pending requests from the arm->vc mbox */
 114
 115    /* Re-enable calls from the IRQ routine */
 116    s->mbox_irq_disabled = false;
 117
 118    /* Update ARM IRQ status */
 119    set = false;
 120    s->mbox[0].config &= ~ARM_MC_IHAVEDATAIRQPEND;
 121    if (!(s->mbox[0].status & ARM_MS_EMPTY)) {
 122        s->mbox[0].config |= ARM_MC_IHAVEDATAIRQPEND;
 123        if (s->mbox[0].config & ARM_MC_IHAVEDATAIRQEN) {
 124            set = true;
 125        }
 126    }
 127    trace_bcm2835_mbox_irq(set);
 128    qemu_set_irq(s->arm_irq, set);
 129}
 130
 131static void bcm2835_mbox_set_irq(void *opaque, int irq, int level)
 132{
 133    BCM2835MboxState *s = opaque;
 134
 135    s->available[irq] = level;
 136
 137    /* avoid recursively calling bcm2835_mbox_update when the interrupt
 138     * status changes due to the ldl_phys call within that function
 139     */
 140    if (!s->mbox_irq_disabled) {
 141        bcm2835_mbox_update(s);
 142    }
 143}
 144
 145static uint64_t bcm2835_mbox_read(void *opaque, hwaddr offset, unsigned size)
 146{
 147    BCM2835MboxState *s = opaque;
 148    uint32_t res = 0;
 149
 150    offset &= 0xff;
 151
 152    switch (offset) {
 153    case 0x80 ... 0x8c: /* MAIL0_READ */
 154        if (s->mbox[0].status & ARM_MS_EMPTY) {
 155            res = MBOX_INVALID_DATA;
 156        } else {
 157            res = mbox_pull(&s->mbox[0], 0);
 158        }
 159        break;
 160
 161    case MAIL0_PEEK:
 162        res = s->mbox[0].reg[0];
 163        break;
 164
 165    case MAIL0_SENDER:
 166        break;
 167
 168    case MAIL0_STATUS:
 169        res = s->mbox[0].status;
 170        break;
 171
 172    case MAIL0_CONFIG:
 173        res = s->mbox[0].config;
 174        break;
 175
 176    case MAIL1_STATUS:
 177        res = s->mbox[1].status;
 178        break;
 179
 180    default:
 181        qemu_log_mask(LOG_UNIMP, "%s: Unsupported offset 0x%"HWADDR_PRIx"\n",
 182                      __func__, offset);
 183        trace_bcm2835_mbox_read(size, offset, res);
 184        return 0;
 185    }
 186    trace_bcm2835_mbox_read(size, offset, res);
 187
 188    bcm2835_mbox_update(s);
 189
 190    return res;
 191}
 192
 193static void bcm2835_mbox_write(void *opaque, hwaddr offset,
 194                               uint64_t value, unsigned size)
 195{
 196    BCM2835MboxState *s = opaque;
 197    hwaddr childaddr;
 198    uint8_t ch;
 199
 200    offset &= 0xff;
 201
 202    trace_bcm2835_mbox_write(size, offset, value);
 203    switch (offset) {
 204    case MAIL0_SENDER:
 205        break;
 206
 207    case MAIL0_CONFIG:
 208        s->mbox[0].config &= ~ARM_MC_IHAVEDATAIRQEN;
 209        s->mbox[0].config |= value & ARM_MC_IHAVEDATAIRQEN;
 210        break;
 211
 212    case 0xa0 ... 0xac: /* MAIL1_WRITE */
 213        if (s->mbox[1].status & ARM_MS_FULL) {
 214            /* Mailbox full */
 215            qemu_log_mask(LOG_GUEST_ERROR, "%s: mailbox full\n", __func__);
 216        } else {
 217            ch = value & 0xf;
 218            if (ch < MBOX_CHAN_COUNT) {
 219                childaddr = ch << MBOX_AS_CHAN_SHIFT;
 220                if (ldl_le_phys(&s->mbox_as, childaddr + MBOX_AS_PENDING)) {
 221                    /* Child busy, push delayed. Push it in the arm->vc mbox */
 222                    mbox_push(&s->mbox[1], value);
 223                } else {
 224                    /* Push it directly to the child device */
 225                    stl_le_phys(&s->mbox_as, childaddr, value);
 226                }
 227            } else {
 228                /* Invalid channel number */
 229                qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid channel %u\n",
 230                              __func__, ch);
 231            }
 232        }
 233        break;
 234
 235    default:
 236        qemu_log_mask(LOG_UNIMP, "%s: Unsupported offset 0x%"HWADDR_PRIx
 237                                 " value 0x%"PRIx64"\n",
 238                      __func__, offset, value);
 239        return;
 240    }
 241
 242    bcm2835_mbox_update(s);
 243}
 244
 245static const MemoryRegionOps bcm2835_mbox_ops = {
 246    .read = bcm2835_mbox_read,
 247    .write = bcm2835_mbox_write,
 248    .endianness = DEVICE_NATIVE_ENDIAN,
 249    .valid.min_access_size = 4,
 250    .valid.max_access_size = 4,
 251};
 252
 253/* vmstate of a single mailbox */
 254static const VMStateDescription vmstate_bcm2835_mbox_box = {
 255    .name = TYPE_BCM2835_MBOX "_box",
 256    .version_id = 1,
 257    .minimum_version_id = 1,
 258    .fields = (VMStateField[]) {
 259        VMSTATE_UINT32_ARRAY(reg, BCM2835Mbox, MBOX_SIZE),
 260        VMSTATE_UINT32(count, BCM2835Mbox),
 261        VMSTATE_UINT32(status, BCM2835Mbox),
 262        VMSTATE_UINT32(config, BCM2835Mbox),
 263        VMSTATE_END_OF_LIST()
 264    }
 265};
 266
 267/* vmstate of the entire device */
 268static const VMStateDescription vmstate_bcm2835_mbox = {
 269    .name = TYPE_BCM2835_MBOX,
 270    .version_id = 1,
 271    .minimum_version_id = 1,
 272    .minimum_version_id_old = 1,
 273    .fields      = (VMStateField[]) {
 274        VMSTATE_BOOL_ARRAY(available, BCM2835MboxState, MBOX_CHAN_COUNT),
 275        VMSTATE_STRUCT_ARRAY(mbox, BCM2835MboxState, 2, 1,
 276                             vmstate_bcm2835_mbox_box, BCM2835Mbox),
 277        VMSTATE_END_OF_LIST()
 278    }
 279};
 280
 281static void bcm2835_mbox_init(Object *obj)
 282{
 283    BCM2835MboxState *s = BCM2835_MBOX(obj);
 284
 285    memory_region_init_io(&s->iomem, obj, &bcm2835_mbox_ops, s,
 286                          TYPE_BCM2835_MBOX, 0x400);
 287    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
 288    sysbus_init_irq(SYS_BUS_DEVICE(s), &s->arm_irq);
 289    qdev_init_gpio_in(DEVICE(s), bcm2835_mbox_set_irq, MBOX_CHAN_COUNT);
 290}
 291
 292static void bcm2835_mbox_reset(DeviceState *dev)
 293{
 294    BCM2835MboxState *s = BCM2835_MBOX(dev);
 295    int n;
 296
 297    mbox_reset(&s->mbox[0]);
 298    mbox_reset(&s->mbox[1]);
 299    s->mbox_irq_disabled = false;
 300    for (n = 0; n < MBOX_CHAN_COUNT; n++) {
 301        s->available[n] = false;
 302    }
 303}
 304
 305static void bcm2835_mbox_realize(DeviceState *dev, Error **errp)
 306{
 307    BCM2835MboxState *s = BCM2835_MBOX(dev);
 308    Object *obj;
 309    Error *err = NULL;
 310
 311    obj = object_property_get_link(OBJECT(dev), "mbox-mr", &err);
 312    if (obj == NULL) {
 313        error_setg(errp, "%s: required mbox-mr link not found: %s",
 314                   __func__, error_get_pretty(err));
 315        return;
 316    }
 317
 318    s->mbox_mr = MEMORY_REGION(obj);
 319    address_space_init(&s->mbox_as, s->mbox_mr, TYPE_BCM2835_MBOX "-memory");
 320    bcm2835_mbox_reset(dev);
 321}
 322
 323static void bcm2835_mbox_class_init(ObjectClass *klass, void *data)
 324{
 325    DeviceClass *dc = DEVICE_CLASS(klass);
 326
 327    dc->realize = bcm2835_mbox_realize;
 328    dc->reset = bcm2835_mbox_reset;
 329    dc->vmsd = &vmstate_bcm2835_mbox;
 330}
 331
 332static TypeInfo bcm2835_mbox_info = {
 333    .name          = TYPE_BCM2835_MBOX,
 334    .parent        = TYPE_SYS_BUS_DEVICE,
 335    .instance_size = sizeof(BCM2835MboxState),
 336    .class_init    = bcm2835_mbox_class_init,
 337    .instance_init = bcm2835_mbox_init,
 338};
 339
 340static void bcm2835_mbox_register_types(void)
 341{
 342    type_register_static(&bcm2835_mbox_info);
 343}
 344
 345type_init(bcm2835_mbox_register_types)
 346