arm_gicv2m: Add GICv2m widget to support MSIs

The ARM GICv2m widget is a little device that handles MSI interrupt
writes to a trigger register and ties them to a range of interrupt lines
wires to the GIC.  It has a few status/id registers and the interrupt wires,
and that's about it.

A board instantiates the device by setting the base SPI number and
number SPIs for the frame.  The base-spi parameter is indexed in the SPI
number space only, so base-spi == 0, means IRQ number 32.  When a device
(the PCI host controller) writes to the trigger register, the payload is
the GIC IRQ number, so we have to subtract 32 from that and then index
into our frame of SPIs.

When instantiating a GICv2m device, tell PCI that we have instantiated
something that can deal with MSIs.  We rely on the board actually wiring
up the GICv2m to the PCI host controller.

Reviewed-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Message-id: 1432897270-7780-3-git-send-email-christoffer.dall@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 191 insertions, 0 deletions

diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
index 843864a..092d8a8 100644
--- a/hw/intc/Makefile.objs
+++ b/hw/intc/Makefile.objs
@@ -11,6 +11,7 @@ common-obj-$(CONFIG_SLAVIO) += slavio_intctl.o
 common-obj-$(CONFIG_IOAPIC) += ioapic_common.o
 common-obj-$(CONFIG_ARM_GIC) += arm_gic_common.o
 common-obj-$(CONFIG_ARM_GIC) += arm_gic.o
+common-obj-$(CONFIG_ARM_GIC) += arm_gicv2m.o
 common-obj-$(CONFIG_OPENPIC) += openpic.o
 
 obj-$(CONFIG_APIC) += apic.o apic_common.o
diff --git a/hw/intc/arm_gicv2m.c b/hw/intc/arm_gicv2m.c
new file mode 100644
index 0000000..9f84f72
--- /dev/null
+++ b/hw/intc/arm_gicv2m.c
@@ -0,0 +1,190 @@
+/*
+ *  GICv2m extension for MSI/MSI-x support with a GICv2-based system
+ *
+ * Copyright (C) 2015 Linaro, All rights reserved.
+ *
+ * Author: Christoffer Dall <christoffer.dall@linaro.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* This file implements an emulated GICv2m widget as described in the ARM
+ * Server Base System Architecture (SBSA) specification Version 2.2
+ * (ARM-DEN-0029 v2.2) pages 35-39 without any optional implementation defined
+ * identification registers and with a single non-secure MSI register frame.
+ */
+
+#include "hw/sysbus.h"
+#include "hw/pci/msi.h"
+
+#define TYPE_ARM_GICV2M "arm-gicv2m"
+#define ARM_GICV2M(obj) OBJECT_CHECK(ARMGICv2mState, (obj), TYPE_ARM_GICV2M)
+
+#define GICV2M_NUM_SPI_MAX 128
+
+#define V2M_MSI_TYPER           0x008
+#define V2M_MSI_SETSPI_NS       0x040
+#define V2M_MSI_IIDR            0xFCC
+#define V2M_IIDR0               0xFD0
+#define V2M_IIDR11              0xFFC
+
+#define PRODUCT_ID_QEMU         0x51 /* ASCII code Q */
+
+typedef struct ARMGICv2mState {
+    SysBusDevice parent_obj;
+
+    MemoryRegion iomem;
+    qemu_irq spi[GICV2M_NUM_SPI_MAX];
+
+    uint32_t base_spi;
+    uint32_t num_spi;
+} ARMGICv2mState;
+
+static void gicv2m_set_irq(void *opaque, int irq)
+{
+    ARMGICv2mState *s = (ARMGICv2mState *)opaque;
+
+    qemu_irq_pulse(s->spi[irq]);
+}
+
+static uint64_t gicv2m_read(void *opaque, hwaddr offset,
+                            unsigned size)
+{
+    ARMGICv2mState *s = (ARMGICv2mState *)opaque;
+    uint32_t val;
+
+    if (size != 4) {
+        qemu_log_mask(LOG_GUEST_ERROR, "gicv2m_read: bad size %u\n", size);
+        return 0;
+    }
+
+    switch (offset) {
+    case V2M_MSI_TYPER:
+        val = (s->base_spi + 32) << 16;
+        val |= s->num_spi;
+        return val;
+    case V2M_MSI_IIDR:
+        /* We don't have any valid implementor so we leave that field as zero
+         * and we return 0 in the arch revision as per the spec.
+         */
+        return (PRODUCT_ID_QEMU << 20);
+    case V2M_IIDR0 ... V2M_IIDR11:
+        /* We do not implement any optional identification registers and the
+         * mandatory MSI_PIDR2 register reads as 0x0, so we capture all
+         * implementation defined registers here.
+         */
+        return 0;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "gicv2m_read: Bad offset %x\n", (int)offset);
+        return 0;
+    }
+}
+
+static void gicv2m_write(void *opaque, hwaddr offset,
+                        uint64_t value, unsigned size)
+{
+    ARMGICv2mState *s = (ARMGICv2mState *)opaque;
+
+    if (size != 2 && size != 4) {
+        qemu_log_mask(LOG_GUEST_ERROR, "gicv2m_write: bad size %u\n", size);
+        return;
+    }
+
+    switch (offset) {
+    case V2M_MSI_SETSPI_NS: {
+        int spi;
+
+        spi = (value & 0x3ff) - (s->base_spi + 32);
+        if (spi >= 0 && spi < s->num_spi) {
+            gicv2m_set_irq(s, spi);
+        }
+        return;
+    }
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "gicv2m_write: Bad offset %x\n", (int)offset);
+    }
+}
+
+static const MemoryRegionOps gicv2m_ops = {
+    .read = gicv2m_read,
+    .write = gicv2m_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static void gicv2m_realize(DeviceState *dev, Error **errp)
+{
+    ARMGICv2mState *s = ARM_GICV2M(dev);
+    int i;
+
+    if (s->num_spi > GICV2M_NUM_SPI_MAX) {
+        error_setg(errp,
+                   "requested %u SPIs exceeds GICv2m frame maximum %d",
+                   s->num_spi, GICV2M_NUM_SPI_MAX);
+        return;
+    }
+
+    if (s->base_spi + 32 > 1020 - s->num_spi) {
+        error_setg(errp,
+                   "requested base SPI %u+%u exceeds max. number 1020",
+                   s->base_spi + 32, s->num_spi);
+        return;
+    }
+
+    for (i = 0; i < s->num_spi; i++) {
+        sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->spi[i]);
+    }
+
+    msi_supported = true;
+}
+
+static void gicv2m_init(Object *obj)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+    ARMGICv2mState *s = ARM_GICV2M(obj);
+
+    memory_region_init_io(&s->iomem, OBJECT(s), &gicv2m_ops, s,
+                          "gicv2m", 0x1000);
+    sysbus_init_mmio(sbd, &s->iomem);
+}
+
+static Property gicv2m_properties[] = {
+    DEFINE_PROP_UINT32("base-spi", ARMGICv2mState, base_spi, 0),
+    DEFINE_PROP_UINT32("num-spi", ARMGICv2mState, num_spi, 64),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void gicv2m_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = gicv2m_properties;
+    dc->realize = gicv2m_realize;
+}
+
+static const TypeInfo gicv2m_info = {
+    .name          = TYPE_ARM_GICV2M,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(ARMGICv2mState),
+    .instance_init = gicv2m_init,
+    .class_init    = gicv2m_class_init,
+};
+
+static void gicv2m_register_types(void)
+{
+    type_register_static(&gicv2m_info);
+}
+
+type_init(gicv2m_register_types)