hw/mips: implement Global Interrupt Controller

The Global Interrupt Controller (GIC) is responsible for mapping each
internal and external interrupt to the correct location for servicing.

The internal representation of registers is different from the specification
in order to consolidate information for each GIC Interrupt Sources and Virtual
Processors with same functionalities. For example SH_MAP00_VP00 registers are
defined like each bit represents a VP but in this implementation the equivalent
map_vp contains VP number in integer form for ease accesses. When it is being
accessed via read write functions an internal data is converted back into the
original format as the specification.

Limitations:
Level triggering only
GIC CounterHi not implemented (Countbits = 32bits)
DINT not implemented
Local WatchDog, Fast Debug Channel, Perf Counter not implemented

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>

2 files changed, 461 insertions, 0 deletions

diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
index 530df2e..05ec21b 100644
--- a/hw/intc/Makefile.objs
+++ b/hw/intc/Makefile.objs
@@ -37,3 +37,4 @@ obj-$(CONFIG_S390_FLIC) += s390_flic.o
 obj-$(CONFIG_S390_FLIC_KVM) += s390_flic_kvm.o
 obj-$(CONFIG_ASPEED_SOC) += aspeed_vic.o
 obj-$(CONFIG_ARM_GIC) += arm_gicv3_cpuif.o
+obj-$(CONFIG_MIPS_CPS) += mips_gic.o
diff --git a/hw/intc/mips_gic.c b/hw/intc/mips_gic.c
new file mode 100644
index 0000000..6e25773
--- /dev/null
+++ b/hw/intc/mips_gic.c
@@ -0,0 +1,460 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
+ * Authors: Sanjay Lal <sanjayl@kymasys.com>
+ *
+ * Copyright (C) 2016 Imagination Technologies
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qapi/error.h"
+#include "hw/hw.h"
+#include "hw/sysbus.h"
+#include "exec/memory.h"
+#include "sysemu/sysemu.h"
+#include "sysemu/kvm.h"
+#include "kvm_mips.h"
+#include "hw/intc/mips_gic.h"
+
+static void mips_gic_set_vp_irq(MIPSGICState *gic, int vp, int pin, int level)
+{
+    int ored_level = level;
+    int i;
+
+    /* ORing pending registers sharing same pin */
+    if (!ored_level) {
+        for (i = 0; i < gic->num_irq; i++) {
+            if ((gic->irq_state[i].map_pin & GIC_MAP_MSK) == pin &&
+                    gic->irq_state[i].map_vp == vp &&
+                    gic->irq_state[i].enabled) {
+                ored_level |= gic->irq_state[i].pending;
+            }
+            if (ored_level) {
+                /* no need to iterate all interrupts */
+                break;
+            }
+        }
+        if (((gic->vps[vp].compare_map & GIC_MAP_MSK) == pin) &&
+                (gic->vps[vp].mask & GIC_VP_MASK_CMP_MSK)) {
+            /* ORing with local pending register (count/compare) */
+            ored_level |= (gic->vps[vp].pend & GIC_VP_MASK_CMP_MSK) >>
+                          GIC_VP_MASK_CMP_SHF;
+        }
+    }
+    if (kvm_enabled())  {
+        kvm_mips_set_ipi_interrupt(mips_env_get_cpu(gic->vps[vp].env),
+                                   pin + GIC_CPU_PIN_OFFSET,
+                                   ored_level);
+    } else {
+        qemu_set_irq(gic->vps[vp].env->irq[pin + GIC_CPU_PIN_OFFSET],
+                     ored_level);
+    }
+}
+
+static void gic_set_irq(void *opaque, int n_IRQ, int level)
+{
+    MIPSGICState *gic = (MIPSGICState *) opaque;
+    int vp = gic->irq_state[n_IRQ].map_vp;
+    int pin = gic->irq_state[n_IRQ].map_pin & GIC_MAP_MSK;
+
+    gic->irq_state[n_IRQ].pending = (uint8_t) level;
+    if (!gic->irq_state[n_IRQ].enabled) {
+        /* GIC interrupt source disabled */
+        return;
+    }
+    if (vp < 0 || vp >= gic->num_vps) {
+        return;
+    }
+    mips_gic_set_vp_irq(gic, vp, pin, level);
+}
+
+#define OFFSET_CHECK(c)                         \
+    do {                                        \
+        if (!(c)) {                             \
+            goto bad_offset;                    \
+        }                                       \
+    } while (0)
+
+/* GIC Read VP Local/Other Registers */
+static uint64_t gic_read_vp(MIPSGICState *gic, uint32_t vp_index, hwaddr addr,
+                            unsigned size)
+{
+    switch (addr) {
+    case GIC_VP_CTL_OFS:
+        return gic->vps[vp_index].ctl;
+    case GIC_VP_PEND_OFS:
+        mips_gictimer_get_sh_count(gic->gic_timer);
+        return gic->vps[vp_index].pend;
+    case GIC_VP_MASK_OFS:
+        return gic->vps[vp_index].mask;
+    case GIC_VP_COMPARE_MAP_OFS:
+        return gic->vps[vp_index].compare_map;
+    case GIC_VP_OTHER_ADDR_OFS:
+        return gic->vps[vp_index].other_addr;
+    case GIC_VP_IDENT_OFS:
+        return vp_index;
+    case GIC_VP_COMPARE_LO_OFS:
+        return mips_gictimer_get_vp_compare(gic->gic_timer, vp_index);
+    case GIC_VP_COMPARE_HI_OFS:
+        return 0;
+    default:
+        qemu_log_mask(LOG_UNIMP, "Read %d bytes at GIC offset LOCAL/OTHER 0x%"
+                      PRIx64 "\n", size, addr);
+        break;
+    }
+    return 0;
+}
+
+static uint64_t gic_read(void *opaque, hwaddr addr, unsigned size)
+{
+    MIPSGICState *gic = (MIPSGICState *) opaque;
+    uint32_t vp_index = current_cpu->cpu_index;
+    uint64_t ret = 0;
+    int i, base, irq_src;
+    uint32_t other_index;
+
+    switch (addr) {
+    case GIC_SH_CONFIG_OFS:
+        ret = gic->sh_config | (mips_gictimer_get_countstop(gic->gic_timer) <<
+                               GIC_SH_CONFIG_COUNTSTOP_SHF);
+        break;
+    case GIC_SH_COUNTERLO_OFS:
+        ret = mips_gictimer_get_sh_count(gic->gic_timer);
+        break;
+    case GIC_SH_COUNTERHI_OFS:
+        ret = 0;
+        break;
+    case GIC_SH_PEND_OFS ... GIC_SH_PEND_LAST_OFS:
+        /* each bit represents pending status for an interrupt pin */
+        base = (addr - GIC_SH_PEND_OFS) * 8;
+        OFFSET_CHECK((base + size * 8) <= gic->num_irq);
+        for (i = 0; i < size * 8; i++) {
+            ret |= (uint64_t) (gic->irq_state[base + i].pending) << i;
+        }
+        break;
+    case GIC_SH_MASK_OFS ... GIC_SH_MASK_LAST_OFS:
+        /* each bit represents status for an interrupt pin */
+        base = (addr - GIC_SH_MASK_OFS) * 8;
+        OFFSET_CHECK((base + size * 8) <= gic->num_irq);
+        for (i = 0; i < size * 8; i++) {
+            ret |= (uint64_t) (gic->irq_state[base + i].enabled) << i;
+        }
+        break;
+    case GIC_SH_MAP0_PIN_OFS ... GIC_SH_MAP255_PIN_OFS:
+        /* 32 bits per a pin */
+        irq_src = (addr - GIC_SH_MAP0_PIN_OFS) / 4;
+        OFFSET_CHECK(irq_src < gic->num_irq);
+        ret = gic->irq_state[irq_src].map_pin;
+        break;
+    case GIC_SH_MAP0_VP_OFS ... GIC_SH_MAP255_VP_LAST_OFS:
+        /* up to 32 bytes per a pin */
+        irq_src = (addr - GIC_SH_MAP0_VP_OFS) / 32;
+        OFFSET_CHECK(irq_src < gic->num_irq);
+        if ((gic->irq_state[irq_src].map_vp) >= 0) {
+            ret = (uint64_t) 1 << (gic->irq_state[irq_src].map_vp);
+        } else {
+            ret = 0;
+        }
+        break;
+    /* VP-Local Register */
+    case VP_LOCAL_SECTION_OFS ... (VP_LOCAL_SECTION_OFS + GIC_VL_BRK_GROUP):
+        ret = gic_read_vp(gic, vp_index, addr - VP_LOCAL_SECTION_OFS, size);
+        break;
+    /* VP-Other Register */
+    case VP_OTHER_SECTION_OFS ... (VP_OTHER_SECTION_OFS + GIC_VL_BRK_GROUP):
+        other_index = gic->vps[vp_index].other_addr;
+        ret = gic_read_vp(gic, other_index, addr - VP_OTHER_SECTION_OFS, size);
+        break;
+    /* User-Mode Visible section */
+    case USM_VISIBLE_SECTION_OFS + GIC_USER_MODE_COUNTERLO:
+        ret = mips_gictimer_get_sh_count(gic->gic_timer);
+        break;
+    case USM_VISIBLE_SECTION_OFS + GIC_USER_MODE_COUNTERHI:
+        ret = 0;
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP, "Read %d bytes at GIC offset 0x%" PRIx64 "\n",
+                      size, addr);
+        break;
+    }
+    return ret;
+bad_offset:
+    qemu_log_mask(LOG_GUEST_ERROR, "Wrong GIC offset at 0x%" PRIx64 "\n", addr);
+    return 0;
+}
+
+static void gic_timer_expire_cb(void *opaque, uint32_t vp_index)
+{
+    MIPSGICState *gic = opaque;
+
+    gic->vps[vp_index].pend |= (1 << GIC_LOCAL_INT_COMPARE);
+    if (gic->vps[vp_index].pend &
+            (gic->vps[vp_index].mask & GIC_VP_MASK_CMP_MSK)) {
+        if (gic->vps[vp_index].compare_map & GIC_MAP_TO_PIN_MSK) {
+            /* it is safe to set the irq high regardless of other GIC IRQs */
+            uint32_t pin = (gic->vps[vp_index].compare_map & GIC_MAP_MSK);
+            qemu_irq_raise(gic->vps[vp_index].env->irq
+                           [pin + GIC_CPU_PIN_OFFSET]);
+        }
+    }
+}
+
+static void gic_timer_store_vp_compare(MIPSGICState *gic, uint32_t vp_index,
+                                       uint64_t compare)
+{
+    gic->vps[vp_index].pend &= ~(1 << GIC_LOCAL_INT_COMPARE);
+    if (gic->vps[vp_index].compare_map & GIC_MAP_TO_PIN_MSK) {
+        uint32_t pin = (gic->vps[vp_index].compare_map & GIC_MAP_MSK);
+        mips_gic_set_vp_irq(gic, vp_index, pin, 0);
+    }
+    mips_gictimer_store_vp_compare(gic->gic_timer, vp_index, compare);
+}
+
+/* GIC Write VP Local/Other Registers */
+static void gic_write_vp(MIPSGICState *gic, uint32_t vp_index, hwaddr addr,
+                              uint64_t data, unsigned size)
+{
+    switch (addr) {
+    case GIC_VP_CTL_OFS:
+        /* EIC isn't supported */
+        break;
+    case GIC_VP_RMASK_OFS:
+        gic->vps[vp_index].mask &= ~(data & GIC_VP_SET_RESET_MSK) &
+                                   GIC_VP_SET_RESET_MSK;
+        break;
+    case GIC_VP_SMASK_OFS:
+        gic->vps[vp_index].mask |= data & GIC_VP_SET_RESET_MSK;
+        break;
+    case GIC_VP_COMPARE_MAP_OFS:
+        /* EIC isn't supported */
+        OFFSET_CHECK((data & GIC_MAP_MSK) <= GIC_CPU_INT_MAX);
+        gic->vps[vp_index].compare_map = data & GIC_MAP_TO_PIN_REG_MSK;
+        break;
+    case GIC_VP_OTHER_ADDR_OFS:
+        OFFSET_CHECK(data < gic->num_vps);
+        gic->vps[vp_index].other_addr = data;
+        break;
+    case GIC_VP_COMPARE_LO_OFS:
+        gic_timer_store_vp_compare(gic, vp_index, data);
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP, "Write %d bytes at GIC offset LOCAL/OTHER "
+                      "0x%" PRIx64" 0x%08" PRIx64 "\n", size, addr, data);
+        break;
+    }
+    return;
+bad_offset:
+    qemu_log_mask(LOG_GUEST_ERROR, "Wrong GIC offset at 0x%" PRIx64 "\n", addr);
+    return;
+}
+
+static void gic_write(void *opaque, hwaddr addr, uint64_t data, unsigned size)
+{
+    int intr;
+    MIPSGICState *gic = (MIPSGICState *) opaque;
+    uint32_t vp_index = current_cpu->cpu_index;
+    int i, base, irq_src;
+    uint32_t other_index;
+
+    switch (addr) {
+    case GIC_SH_CONFIG_OFS:
+        {
+            uint32_t pre_cntstop = mips_gictimer_get_countstop(gic->gic_timer);
+            uint32_t new_cntstop = (data & GIC_SH_CONFIG_COUNTSTOP_MSK) >>
+                                   GIC_SH_CONFIG_COUNTSTOP_SHF;
+            if (pre_cntstop != new_cntstop) {
+                if (new_cntstop == 1) {
+                    mips_gictimer_stop_count(gic->gic_timer);
+                } else {
+                    mips_gictimer_start_count(gic->gic_timer);
+                }
+            }
+        }
+        break;
+    case GIC_SH_COUNTERLO_OFS:
+        if (mips_gictimer_get_countstop(gic->gic_timer)) {
+            mips_gictimer_store_sh_count(gic->gic_timer, data);
+        }
+        break;
+    case GIC_SH_RMASK_OFS ... GIC_SH_RMASK_LAST_OFS:
+        /* up to 64 bits per a pin */
+        base = (addr - GIC_SH_RMASK_OFS) * 8;
+        OFFSET_CHECK((base + size * 8) <= gic->num_irq);
+        for (i = 0; i < size * 8; i++) {
+            gic->irq_state[base + i].enabled &= !((data >> i) & 1);
+        }
+        break;
+    case GIC_SH_WEDGE_OFS:
+        /* Figure out which VP/HW Interrupt this maps to */
+        intr = data & ~GIC_SH_WEDGE_RW_MSK;
+        /* Mask/Enabled Checks */
+        OFFSET_CHECK(intr < gic->num_irq);
+        if (data & GIC_SH_WEDGE_RW_MSK) {
+            gic_set_irq(gic, intr, 1);
+        } else {
+            gic_set_irq(gic, intr, 0);
+        }
+        break;
+    case GIC_SH_SMASK_OFS ... GIC_SH_SMASK_LAST_OFS:
+        /* up to 64 bits per a pin */
+        base = (addr - GIC_SH_SMASK_OFS) * 8;
+        OFFSET_CHECK((base + size * 8) <= gic->num_irq);
+        for (i = 0; i < size * 8; i++) {
+            gic->irq_state[base + i].enabled |= (data >> i) & 1;
+        }
+        break;
+    case GIC_SH_MAP0_PIN_OFS ... GIC_SH_MAP255_PIN_OFS:
+        /* 32 bits per a pin */
+        irq_src = (addr - GIC_SH_MAP0_PIN_OFS) / 4;
+        OFFSET_CHECK(irq_src < gic->num_irq);
+        /* EIC isn't supported */
+        OFFSET_CHECK((data & GIC_MAP_MSK) <= GIC_CPU_INT_MAX);
+        gic->irq_state[irq_src].map_pin = data & GIC_MAP_TO_PIN_REG_MSK;
+        break;
+    case GIC_SH_MAP0_VP_OFS ... GIC_SH_MAP255_VP_LAST_OFS:
+        /* up to 32 bytes per a pin */
+        irq_src = (addr - GIC_SH_MAP0_VP_OFS) / 32;
+        OFFSET_CHECK(irq_src < gic->num_irq);
+        data = data ? ctz64(data) : -1;
+        OFFSET_CHECK(data < gic->num_vps);
+        gic->irq_state[irq_src].map_vp = data;
+        break;
+    case VP_LOCAL_SECTION_OFS ... (VP_LOCAL_SECTION_OFS + GIC_VL_BRK_GROUP):
+        gic_write_vp(gic, vp_index, addr - VP_LOCAL_SECTION_OFS, data, size);
+        break;
+    case VP_OTHER_SECTION_OFS ... (VP_OTHER_SECTION_OFS + GIC_VL_BRK_GROUP):
+        other_index = gic->vps[vp_index].other_addr;
+        gic_write_vp(gic, other_index, addr - VP_OTHER_SECTION_OFS, data, size);
+        break;
+    case USM_VISIBLE_SECTION_OFS + GIC_USER_MODE_COUNTERLO:
+    case USM_VISIBLE_SECTION_OFS + GIC_USER_MODE_COUNTERHI:
+        /* do nothing. Read-only section */
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP, "Write %d bytes at GIC offset 0x%" PRIx64
+                      " 0x%08" PRIx64 "\n", size, addr, data);
+        break;
+    }
+    return;
+bad_offset:
+    qemu_log_mask(LOG_GUEST_ERROR, "Wrong GIC offset at 0x%" PRIx64 "\n", addr);
+}
+
+static void gic_reset(void *opaque)
+{
+    int i;
+    MIPSGICState *gic = (MIPSGICState *) opaque;
+    int numintrs = (gic->num_irq / 8) - 1;
+
+    gic->sh_config = /* COUNTSTOP = 0 it is accessible via MIPSGICTimer*/
+                     /* CounterHi not implemented */
+                     (0            << GIC_SH_CONFIG_COUNTBITS_SHF) |
+                     (numintrs     << GIC_SH_CONFIG_NUMINTRS_SHF)  |
+                     (gic->num_vps << GIC_SH_CONFIG_PVPS_SHF);
+    for (i = 0; i < gic->num_vps; i++) {
+        gic->vps[i].ctl         = 0x0;
+        gic->vps[i].pend        = 0x0;
+        /* PERFCNT, TIMER and WD not implemented */
+        gic->vps[i].mask        = 0x32;
+        gic->vps[i].compare_map = GIC_MAP_TO_PIN_MSK;
+        mips_gictimer_store_vp_compare(gic->gic_timer, i, 0xffffffff);
+        gic->vps[i].other_addr  = 0x0;
+    }
+    for (i = 0; i < gic->num_irq; i++) {
+        gic->irq_state[i].enabled = 0;
+        gic->irq_state[i].pending = 0;
+        gic->irq_state[i].map_pin = GIC_MAP_TO_PIN_MSK;
+        gic->irq_state[i].map_vp  = -1;
+    }
+    mips_gictimer_store_sh_count(gic->gic_timer, 0);
+    /* COUNTSTOP = 0 */
+    mips_gictimer_start_count(gic->gic_timer);
+}
+
+static const MemoryRegionOps gic_ops = {
+    .read = gic_read,
+    .write = gic_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .max_access_size = 8,
+    },
+};
+
+static void mips_gic_init(Object *obj)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+    MIPSGICState *s = MIPS_GIC(obj);
+
+    memory_region_init_io(&s->mr, OBJECT(s), &gic_ops, s,
+                          "mips-gic", GIC_ADDRSPACE_SZ);
+    sysbus_init_mmio(sbd, &s->mr);
+    qemu_register_reset(gic_reset, s);
+}
+
+static void mips_gic_realize(DeviceState *dev, Error **errp)
+{
+    MIPSGICState *s = MIPS_GIC(dev);
+    CPUState *cs = first_cpu;
+    int i;
+
+    if (s->num_vps > GIC_MAX_VPS) {
+        error_setg(errp, "Exceeded maximum CPUs %d", s->num_vps);
+        return;
+    }
+    if ((s->num_irq > GIC_MAX_INTRS) || (s->num_irq % 8) || (s->num_irq <= 0)) {
+        error_setg(errp, "GIC supports up to %d external interrupts in "
+                   "multiples of 8 : %d", GIC_MAX_INTRS, s->num_irq);
+        return;
+    }
+    s->vps = g_new(MIPSGICVPState, s->num_vps);
+    s->irq_state = g_new(MIPSGICIRQState, s->num_irq);
+    /* Register the env for all VPs with the GIC */
+    for (i = 0; i < s->num_vps; i++) {
+        if (cs != NULL) {
+            s->vps[i].env = cs->env_ptr;
+            cs = CPU_NEXT(cs);
+        } else {
+            error_setg(errp,
+               "Unable to initialize GIC, CPUState for CPU#%d not valid.", i);
+            return;
+        }
+    }
+    s->gic_timer = mips_gictimer_init(s, s->num_vps, gic_timer_expire_cb);
+    qdev_init_gpio_in(dev, gic_set_irq, s->num_irq);
+    for (i = 0; i < s->num_irq; i++) {
+        s->irq_state[i].irq = qdev_get_gpio_in(dev, i);
+    }
+}
+
+static Property mips_gic_properties[] = {
+    DEFINE_PROP_INT32("num-vp", MIPSGICState, num_vps, 1),
+    DEFINE_PROP_INT32("num-irq", MIPSGICState, num_irq, 256),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void mips_gic_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = mips_gic_properties;
+    dc->realize = mips_gic_realize;
+}
+
+static const TypeInfo mips_gic_info = {
+    .name          = TYPE_MIPS_GIC,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(MIPSGICState),
+    .instance_init = mips_gic_init,
+    .class_init    = mips_gic_class_init,
+};
+
+static void mips_gic_register_types(void)
+{
+    type_register_static(&mips_gic_info);
+}
+
+type_init(mips_gic_register_types)