bcm2835_mbox: add BCM2835 mailboxes

This adds the system mailboxes which are used to communicate with a
number of GPU peripherals on Pi/Pi2.

Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

default-configs/arm-softmmu.mak

@@ -79,6 +79,7 @@ CONFIG_TUSB6010=y
 CONFIG_IMX=y
 CONFIG_MAINSTONE=y
 CONFIG_NSERIES=y
+CONFIG_RASPI=y
 CONFIG_REALVIEW=y
 CONFIG_ZAURUS=y
 CONFIG_ZYNQ=y

hw/misc/Makefile.objs

@@ -36,6 +36,7 @@ obj-$(CONFIG_OMAP) += omap_gpmc.o
 obj-$(CONFIG_OMAP) += omap_l4.o
 obj-$(CONFIG_OMAP) += omap_sdrc.o
 obj-$(CONFIG_OMAP) += omap_tap.o
+obj-$(CONFIG_RASPI) += bcm2835_mbox.o
 obj-$(CONFIG_SLAVIO) += slavio_misc.o
 obj-$(CONFIG_ZYNQ) += zynq_slcr.o
 obj-$(CONFIG_ZYNQ) += zynq-xadc.o

hw/misc/bcm2835_mbox.c

@@ -0,0 +1,333 @@
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ *
+ * This file models the system mailboxes, which are used for
+ * communication with low-bandwidth GPU peripherals. Refs:
+ *   https://github.com/raspberrypi/firmware/wiki/Mailboxes
+ *   https://github.com/raspberrypi/firmware/wiki/Accessing-mailboxes
+ */
+
+#include "hw/misc/bcm2835_mbox.h"
+
+#define MAIL0_PEEK   0x90
+#define MAIL0_SENDER 0x94
+#define MAIL1_STATUS 0xb8
+
+/* Mailbox status register */
+#define MAIL0_STATUS 0x98
+#define ARM_MS_FULL       0x80000000
+#define ARM_MS_EMPTY      0x40000000
+#define ARM_MS_LEVEL      0x400000FF /* Max. value depends on mailbox depth */
+
+/* MAILBOX config/status register */
+#define MAIL0_CONFIG 0x9c
+/* ANY write to this register clears the error bits! */
+#define ARM_MC_IHAVEDATAIRQEN    0x00000001 /* mbox irq enable:  has data */
+#define ARM_MC_IHAVESPACEIRQEN   0x00000002 /* mbox irq enable:  has space */
+#define ARM_MC_OPPISEMPTYIRQEN   0x00000004 /* mbox irq enable: Opp is empty */
+#define ARM_MC_MAIL_CLEAR        0x00000008 /* mbox clear write 1, then  0 */
+#define ARM_MC_IHAVEDATAIRQPEND  0x00000010 /* mbox irq pending:  has space */
+#define ARM_MC_IHAVESPACEIRQPEND 0x00000020 /* mbox irq pending: Opp is empty */
+#define ARM_MC_OPPISEMPTYIRQPEND 0x00000040 /* mbox irq pending */
+/* Bit 7 is unused */
+#define ARM_MC_ERRNOOWN   0x00000100 /* error : none owner read from mailbox */
+#define ARM_MC_ERROVERFLW 0x00000200 /* error : write to fill mailbox */
+#define ARM_MC_ERRUNDRFLW 0x00000400 /* error : read from empty mailbox */
+
+static void mbox_update_status(BCM2835Mbox *mb)
+{
+    mb->status &= ~(ARM_MS_EMPTY | ARM_MS_FULL);
+    if (mb->count == 0) {
+        mb->status |= ARM_MS_EMPTY;
+    } else if (mb->count == MBOX_SIZE) {
+        mb->status |= ARM_MS_FULL;
+    }
+}
+
+static void mbox_reset(BCM2835Mbox *mb)
+{
+    int n;
+
+    mb->count = 0;
+    mb->config = 0;
+    for (n = 0; n < MBOX_SIZE; n++) {
+        mb->reg[n] = MBOX_INVALID_DATA;
+    }
+    mbox_update_status(mb);
+}
+
+static uint32_t mbox_pull(BCM2835Mbox *mb, int index)
+{
+    int n;
+    uint32_t val;
+
+    assert(mb->count > 0);
+    assert(index < mb->count);
+
+    val = mb->reg[index];
+    for (n = index + 1; n < mb->count; n++) {
+        mb->reg[n - 1] = mb->reg[n];
+    }
+    mb->count--;
+    mb->reg[mb->count] = MBOX_INVALID_DATA;
+
+    mbox_update_status(mb);
+
+    return val;
+}
+
+static void mbox_push(BCM2835Mbox *mb, uint32_t val)
+{
+    assert(mb->count < MBOX_SIZE);
+    mb->reg[mb->count++] = val;
+    mbox_update_status(mb);
+}
+
+static void bcm2835_mbox_update(BCM2835MboxState *s)
+{
+    uint32_t value;
+    bool set;
+    int n;
+
+    s->mbox_irq_disabled = true;
+
+    /* Get pending responses and put them in the vc->arm mbox,
+     * as long as it's not full
+     */
+    for (n = 0; n < MBOX_CHAN_COUNT; n++) {
+        while (s->available[n] && !(s->mbox[0].status & ARM_MS_FULL)) {
+            value = ldl_phys(&s->mbox_as, n << MBOX_AS_CHAN_SHIFT);
+            assert(value != MBOX_INVALID_DATA); /* Pending interrupt but no data */
+            mbox_push(&s->mbox[0], value);
+        }
+    }
+
+    /* TODO (?): Try to push pending requests from the arm->vc mbox */
+
+    /* Re-enable calls from the IRQ routine */
+    s->mbox_irq_disabled = false;
+
+    /* Update ARM IRQ status */
+    set = false;
+    s->mbox[0].config &= ~ARM_MC_IHAVEDATAIRQPEND;
+    if (!(s->mbox[0].status & ARM_MS_EMPTY)) {
+        s->mbox[0].config |= ARM_MC_IHAVEDATAIRQPEND;
+        if (s->mbox[0].config & ARM_MC_IHAVEDATAIRQEN) {
+            set = true;
+        }
+    }
+    qemu_set_irq(s->arm_irq, set);
+}
+
+static void bcm2835_mbox_set_irq(void *opaque, int irq, int level)
+{
+    BCM2835MboxState *s = opaque;
+
+    s->available[irq] = level;
+
+    /* avoid recursively calling bcm2835_mbox_update when the interrupt
+     * status changes due to the ldl_phys call within that function
+     */
+    if (!s->mbox_irq_disabled) {
+        bcm2835_mbox_update(s);
+    }
+}
+
+static uint64_t bcm2835_mbox_read(void *opaque, hwaddr offset, unsigned size)
+{
+    BCM2835MboxState *s = opaque;
+    uint32_t res = 0;
+
+    offset &= 0xff;
+
+    switch (offset) {
+    case 0x80 ... 0x8c: /* MAIL0_READ */
+        if (s->mbox[0].status & ARM_MS_EMPTY) {
+            res = MBOX_INVALID_DATA;
+        } else {
+            res = mbox_pull(&s->mbox[0], 0);
+        }
+        break;
+
+    case MAIL0_PEEK:
+        res = s->mbox[0].reg[0];
+        break;
+
+    case MAIL0_SENDER:
+        break;
+
+    case MAIL0_STATUS:
+        res = s->mbox[0].status;
+        break;
+
+    case MAIL0_CONFIG:
+        res = s->mbox[0].config;
+        break;
+
+    case MAIL1_STATUS:
+        res = s->mbox[1].status;
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                      __func__, offset);
+        return 0;
+    }
+
+    bcm2835_mbox_update(s);
+
+    return res;
+}
+
+static void bcm2835_mbox_write(void *opaque, hwaddr offset,
+                               uint64_t value, unsigned size)
+{
+    BCM2835MboxState *s = opaque;
+    hwaddr childaddr;
+    uint8_t ch;
+
+    offset &= 0xff;
+
+    switch (offset) {
+    case MAIL0_SENDER:
+        break;
+
+    case MAIL0_CONFIG:
+        s->mbox[0].config &= ~ARM_MC_IHAVEDATAIRQEN;
+        s->mbox[0].config |= value & ARM_MC_IHAVEDATAIRQEN;
+        break;
+
+    case 0xa0 ... 0xac: /* MAIL1_WRITE */
+        if (s->mbox[1].status & ARM_MS_FULL) {
+            /* Mailbox full */
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: mailbox full\n", __func__);
+        } else {
+            ch = value & 0xf;
+            if (ch < MBOX_CHAN_COUNT) {
+                childaddr = ch << MBOX_AS_CHAN_SHIFT;
+                if (ldl_phys(&s->mbox_as, childaddr + MBOX_AS_PENDING)) {
+                    /* Child busy, push delayed. Push it in the arm->vc mbox */
+                    mbox_push(&s->mbox[1], value);
+                } else {
+                    /* Push it directly to the child device */
+                    stl_phys(&s->mbox_as, childaddr, value);
+                }
+            } else {
+                /* Invalid channel number */
+                qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid channel %u\n",
+                              __func__, ch);
+            }
+        }
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
+                      __func__, offset);
+        return;
+    }
+
+    bcm2835_mbox_update(s);
+}
+
+static const MemoryRegionOps bcm2835_mbox_ops = {
+    .read = bcm2835_mbox_read,
+    .write = bcm2835_mbox_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid.min_access_size = 4,
+    .valid.max_access_size = 4,
+};
+
+/* vmstate of a single mailbox */
+static const VMStateDescription vmstate_bcm2835_mbox_box = {
+    .name = TYPE_BCM2835_MBOX "_box",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32_ARRAY(reg, BCM2835Mbox, MBOX_SIZE),
+        VMSTATE_UINT32(count, BCM2835Mbox),
+        VMSTATE_UINT32(status, BCM2835Mbox),
+        VMSTATE_UINT32(config, BCM2835Mbox),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+/* vmstate of the entire device */
+static const VMStateDescription vmstate_bcm2835_mbox = {
+    .name = TYPE_BCM2835_MBOX,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField[]) {
+        VMSTATE_BOOL_ARRAY(available, BCM2835MboxState, MBOX_CHAN_COUNT),
+        VMSTATE_STRUCT_ARRAY(mbox, BCM2835MboxState, 2, 1,
+                             vmstate_bcm2835_mbox_box, BCM2835Mbox),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void bcm2835_mbox_init(Object *obj)
+{
+    BCM2835MboxState *s = BCM2835_MBOX(obj);
+
+    memory_region_init_io(&s->iomem, obj, &bcm2835_mbox_ops, s,
+                          TYPE_BCM2835_MBOX, 0x400);
+    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
+    sysbus_init_irq(SYS_BUS_DEVICE(s), &s->arm_irq);
+    qdev_init_gpio_in(DEVICE(s), bcm2835_mbox_set_irq, MBOX_CHAN_COUNT);
+}
+
+static void bcm2835_mbox_reset(DeviceState *dev)
+{
+    BCM2835MboxState *s = BCM2835_MBOX(dev);
+    int n;
+
+    mbox_reset(&s->mbox[0]);
+    mbox_reset(&s->mbox[1]);
+    s->mbox_irq_disabled = false;
+    for (n = 0; n < MBOX_CHAN_COUNT; n++) {
+        s->available[n] = false;
+    }
+}
+
+static void bcm2835_mbox_realize(DeviceState *dev, Error **errp)
+{
+    BCM2835MboxState *s = BCM2835_MBOX(dev);
+    Object *obj;
+    Error *err = NULL;
+
+    obj = object_property_get_link(OBJECT(dev), "mbox-mr", &err);
+    if (obj == NULL) {
+        error_setg(errp, "%s: required mbox-mr link not found: %s",
+                   __func__, error_get_pretty(err));
+        return;
+    }
+
+    s->mbox_mr = MEMORY_REGION(obj);
+    address_space_init(&s->mbox_as, s->mbox_mr, NULL);
+    bcm2835_mbox_reset(dev);
+}
+
+static void bcm2835_mbox_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = bcm2835_mbox_realize;
+    dc->reset = bcm2835_mbox_reset;
+    dc->vmsd = &vmstate_bcm2835_mbox;
+}
+
+static TypeInfo bcm2835_mbox_info = {
+    .name          = TYPE_BCM2835_MBOX,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(BCM2835MboxState),
+    .class_init    = bcm2835_mbox_class_init,
+    .instance_init = bcm2835_mbox_init,
+};
+
+static void bcm2835_mbox_register_types(void)
+{
+    type_register_static(&bcm2835_mbox_info);
+}
+
+type_init(bcm2835_mbox_register_types)

include/hw/misc/bcm2835_mbox.h

@@ -0,0 +1,38 @@
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ */
+
+#ifndef BCM2835_MBOX_H
+#define BCM2835_MBOX_H
+
+#include "bcm2835_mbox_defs.h"
+#include "hw/sysbus.h"
+#include "exec/address-spaces.h"
+
+#define TYPE_BCM2835_MBOX "bcm2835-mbox"
+#define BCM2835_MBOX(obj) \
+        OBJECT_CHECK(BCM2835MboxState, (obj), TYPE_BCM2835_MBOX)
+
+typedef struct {
+    uint32_t reg[MBOX_SIZE];
+    uint32_t count;
+    uint32_t status;
+    uint32_t config;
+} BCM2835Mbox;
+
+typedef struct {
+    /*< private >*/
+    SysBusDevice busdev;
+    /*< public >*/
+    MemoryRegion *mbox_mr;
+    AddressSpace mbox_as;
+    MemoryRegion iomem;
+    qemu_irq arm_irq;
+
+    bool mbox_irq_disabled;
+    bool available[MBOX_CHAN_COUNT];
+    BCM2835Mbox mbox[2];
+} BCM2835MboxState;
+
+#endif

include/hw/misc/bcm2835_mbox_defs.h

@@ -0,0 +1,27 @@
+/*
+ * Raspberry Pi emulation (c) 2012 Gregory Estrade
+ * This code is licensed under the GNU GPLv2 and later.
+ */
+
+#ifndef BCM2835_MBOX_DEFS_H
+#define BCM2835_MBOX_DEFS_H
+
+/* Constants shared with the ARM identifying separate mailbox channels */
+#define MBOX_CHAN_POWER    0 /* for use by the power management interface */
+#define MBOX_CHAN_FB       1 /* for use by the frame buffer */
+#define MBOX_CHAN_VCHIQ    3 /* for use by the VCHIQ interface */
+#define MBOX_CHAN_PROPERTY 8 /* for use by the property channel */
+#define MBOX_CHAN_COUNT    9
+
+#define MBOX_SIZE          32
+#define MBOX_INVALID_DATA  0x0f
+
+/* Layout of the private address space used for communication between
+ * the mbox device emulation, and child devices: each channel occupies
+ * 16 bytes of address space, but only two registers are presently defined.
+ */
+#define MBOX_AS_CHAN_SHIFT 4
+#define MBOX_AS_DATA       0 /* request / response data (RW at offset 0) */
+#define MBOX_AS_PENDING    4 /* pending response status (RO at offset 4) */
+
+#endif /* BCM2835_MBOX_DEFS_H */