The Ibex core contains a PLIC that although similar to the RISC-V spec
is not RISC-V spec compliant.
This patch implements a Ibex PLIC in a somewhat generic way.
As the current RISC-V PLIC needs tidying up, my hope is that as the Ibex
PLIC move towards spec compliance this PLIC implementation can be
updated until it can replace the current PLIC.
Signed-off-by: Alistair Francis <address@hidden>
---
MAINTAINERS | 2 +
hw/intc/Makefile.objs | 1 +
hw/intc/ibex_plic.c | 261 ++++++++++++++++++++++++++++++++++++
include/hw/intc/ibex_plic.h | 63 +++++++++
4 files changed, 327 insertions(+)
create mode 100644 hw/intc/ibex_plic.c
create mode 100644 include/hw/intc/ibex_plic.h
diff --git a/MAINTAINERS b/MAINTAINERS
index d3d47564ce..f8c3cf6182 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1237,8 +1237,10 @@ L: address@hidden
S: Supported
F: hw/riscv/opentitan.c
F: hw/char/ibex_uart.c
+F: hw/intc/ibex_plic.c
F: include/hw/riscv/opentitan.h
F: include/hw/char/ibex_uart.h
+F: include/hw/intc/ibex_plic.h
SH4 Machines
diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
index f726d87532..a61e6728fe 100644
--- a/hw/intc/Makefile.objs
+++ b/hw/intc/Makefile.objs
@@ -49,3 +49,4 @@ obj-$(CONFIG_ARM_GIC) += arm_gicv3_cpuif.o
obj-$(CONFIG_MIPS_CPS) += mips_gic.o
obj-$(CONFIG_NIOS2) += nios2_iic.o
obj-$(CONFIG_OMPIC) += ompic.o
+obj-$(CONFIG_IBEX) += ibex_plic.o
diff --git a/hw/intc/ibex_plic.c b/hw/intc/ibex_plic.c
new file mode 100644
index 0000000000..35c52d9d16
--- /dev/null
+++ b/hw/intc/ibex_plic.c
@@ -0,0 +1,261 @@
+/*
+ * QEMU RISC-V lowRISC Ibex PLIC
+ *
+ * Copyright (c) 2020 Western Digital
+ *
+ * Documentation avaliable: https://docs.opentitan.org/hw/ip/rv_plic/doc/
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "hw/qdev-properties.h"
+#include "hw/core/cpu.h"
+#include "hw/boards.h"
+#include "hw/pci/msi.h"
+#include "target/riscv/cpu_bits.h"
+#include "target/riscv/cpu.h"
+#include "hw/intc/ibex_plic.h"
+
+static bool addr_between(uint32_t addr, uint32_t base, uint32_t num)
+{
+ uint32_t end = base + (num * 0x04);
+
+ if (addr >= base && addr < end) {
+ return true;
+ }
+
+ return false;
+}
+
+static void ibex_plic_irqs_set_pending(IbexPlicState *s, int irq, bool level)
+{
+ int pending_num = irq / 32;
+
+ s->pending[pending_num] |= level << (irq % 32);
+}
+
+static bool ibex_plic_irqs_pending(IbexPlicState *s, uint32_t context)
+{
+ int i;
+
+ for (i = 0; i < s->pending_num; i++) {
+ uint32_t irq_num = ctz64(s->pending[i]) + (i * 32);
+
+ if (!(s->pending[i] & s->enable[i])) {
+ /* No pending and enabled IRQ */
+ continue;
+ }
+
+ if (s->priority[irq_num] > s->threshold) {
+ if (!s->claim) {
+ s->claim = irq_num;
+ }
+ return true;
+ }
+ }
+
+ return 0;
+}
+
+static uint64_t ibex_plic_read(void *opaque, hwaddr addr,
+ unsigned int size)
+{
+ IbexPlicState *s = opaque;
+ int offset;
+ uint32_t ret = 0;
+
+ if (addr_between(addr, s->pending_base, s->pending_num)) {
+ offset = (addr - s->pending_base) / 4;
+ ret = s->pending[offset];
+ } else if (addr_between(addr, s->source_base, s->source_num)) {
+ qemu_log_mask(LOG_UNIMP,
+ "%s: Interrupt source mode not supported\n", __func__);
+ } else if (addr_between(addr, s->priority_base, s->priority_num)) {
+ offset = (addr - s->priority_base) / 4;
+ ret = s->priority[offset];
+ } else if (addr_between(addr, s->enable_base, s->enable_num)) {
+ offset = (addr - s->enable_base) / 4;
+ ret = s->enable[offset];
+ } else if (addr_between(addr, s->threshold_base, 1)) {
+ ret = s->threshold;
+ } else if (addr_between(addr, s->claim_base, 1)) {
+ int pending_num = s->claim / 32;
+ s->pending[pending_num] &= ~(1 << (s->claim % 32));
+
+ ret = s->claim;
+ }
+
+ return ret;
+}
+
+static void ibex_plic_write(void *opaque, hwaddr addr,
+ uint64_t value, unsigned int size)
+{
+ IbexPlicState *s = opaque;
+
+ if (addr_between(addr, s->pending_base, s->pending_num)) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "%s: Pending registers are read only\n", __func__);
+ } else if (addr_between(addr, s->source_base, s->source_num)) {
+ qemu_log_mask(LOG_UNIMP,
+ "%s: Interrupt source mode not supported\n", __func__);
+ } else if (addr_between(addr, s->priority_base, s->priority_num)) {
+ uint32_t irq = ((addr - s->priority_base) >> 2) + 1;
+ s->priority[irq] = value & 7;
+ } else if (addr_between(addr, s->enable_base, s->enable_num)) {
+ uint32_t enable_reg = (addr - s->enable_base) / 4;
+
+ s->enable[enable_reg] = value;
+ } else if (addr_between(addr, s->threshold_base, 1)) {
+ s->threshold = value & 3;
+ } else if (addr_between(addr, s->claim_base, 1)) {
+ if (s->claim == value) {
+ /* Interrupt was completed */
+ s->claim = 0;
+ }
+ }
+
+ ibex_plic_update(s);
+}
+
+static const MemoryRegionOps ibex_plic_ops = {
+ .read = ibex_plic_read,
+ .write = ibex_plic_write,
+ .endianness = DEVICE_NATIVE_ENDIAN,
+ .valid = {
+ .min_access_size = 4,
+ .max_access_size = 4
+ }
+};
+
+static void ibex_plic_irq_request(void *opaque, int irq, int level)
+{
+ IbexPlicState *s = opaque;
+
+ ibex_plic_irqs_set_pending(s, irq, level > 0);
+ ibex_plic_update(s);
+}
+
+static Property ibex_plic_properties[] = {
+ DEFINE_PROP_UINT32("num-cpus", IbexPlicState, num_cpus, 1),
+ DEFINE_PROP_UINT32("num-sources", IbexPlicState, num_sources, 80),
+
+ DEFINE_PROP_UINT32("pending-base", IbexPlicState, pending_base, 0),
+ DEFINE_PROP_UINT32("pending-num", IbexPlicState, pending_num, 3),
+
+ DEFINE_PROP_UINT32("source-base", IbexPlicState, source_base, 0x0c),
+ DEFINE_PROP_UINT32("source-num", IbexPlicState, source_num, 3),
+
+ DEFINE_PROP_UINT32("priority-base", IbexPlicState, priority_base, 0x18),
+ DEFINE_PROP_UINT32("priority-num", IbexPlicState, priority_num, 80),
+
+ DEFINE_PROP_UINT32("enable-base", IbexPlicState, enable_base, 0x200),
+ DEFINE_PROP_UINT32("enable-num", IbexPlicState, enable_num, 3),
+
+ DEFINE_PROP_UINT32("threshold-base", IbexPlicState, threshold_base, 0x20c),
+
+ DEFINE_PROP_UINT32("claim-base", IbexPlicState, claim_base, 0x210),
+ DEFINE_PROP_END_OF_LIST(),
+};
+
+static void ibex_plic_init(Object *obj)
+{
+ IbexPlicState *s = IBEX_PLIC(obj);
+
+ memory_region_init_io(&s->mmio, obj, &ibex_plic_ops, s,
+ TYPE_IBEX_PLIC, 0x400);
+ sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
+}
+
+static void ibex_plic_realize(DeviceState *dev, Error **errp)
+{
+ IbexPlicState *s = IBEX_PLIC(dev);
+ int i;
+
+ s->pending = g_new0(uint32_t, s->pending_num);
+ s->source = g_new0(uint32_t, s->source_num);
+ s->priority = g_new0(uint32_t, s->priority_num);
+ s->enable = g_new0(uint32_t, s->enable_num);
+
+ qdev_init_gpio_in(dev, ibex_plic_irq_request, s->num_sources);
+
+ /*
+ * We can't allow the supervisor to control SEIP as this would allow the
+ * supervisor to clear a pending external interrupt which will result in
+ * a lost interrupt in the case a PLIC is attached. The SEIP bit must be
+ * hardware controlled when a PLIC is attached.
+ */
+ MachineState *ms = MACHINE(qdev_get_machine());
+ unsigned int smp_cpus = ms->smp.cpus;
+ for (i = 0; i < smp_cpus; i++) {
+ RISCVCPU *cpu = RISCV_CPU(qemu_get_cpu(i));
+ if (riscv_cpu_claim_interrupts(cpu, MIP_SEIP) < 0) {
+ error_report("SEIP already claimed");
+ exit(1);
+ }
+ }
+
+ msi_nonbroken = true;
+}
+
+static void ibex_plic_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+
+ dc->reset = ibex_plic_reset;
+ device_class_set_props(dc, ibex_plic_properties);
+ dc->realize = ibex_plic_realize;
+}
+
+static const TypeInfo ibex_plic_info = {
+ .name = TYPE_IBEX_PLIC,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(IbexPlicState),
+ .instance_init = ibex_plic_init,
+ .class_init = ibex_plic_class_init,
+};
+
+static void ibex_plic_register_types(void)
+{
+ type_register_static(&ibex_plic_info);
+}
+
+type_init(ibex_plic_register_types)
diff --git a/include/hw/intc/ibex_plic.h b/include/hw/intc/ibex_plic.h
new file mode 100644
index 0000000000..ddc7909903
--- /dev/null
+++ b/include/hw/intc/ibex_plic.h
@@ -0,0 +1,63 @@
+/*
+ * QEMU RISC-V lowRISC Ibex PLIC
+ *
+ * Copyright (c) 2020 Western Digital
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_IBEX_PLIC_H
+#define HW_IBEX_PLIC_H
+
+#include "hw/sysbus.h"
+
+#define TYPE_IBEX_PLIC "ibex-plic"
+#define IBEX_PLIC(obj) \
+ OBJECT_CHECK(IbexPlicState, (obj), TYPE_IBEX_PLIC)
+
+typedef struct IbexPlicState {
+ /*< private >*/
+ SysBusDevice parent_obj;
+
+ /*< public >*/
+ MemoryRegion mmio;
+
+ uint32_t *pending;
+ uint32_t *source;
+ uint32_t *priority;
+ uint32_t *enable;
+ uint32_t threshold;
+ uint32_t claim;
+
+ /* config */
+ uint32_t num_cpus;
+ uint32_t num_sources;
+
+ uint32_t pending_base;
+ uint32_t pending_num;
+
+ uint32_t source_base;
+ uint32_t source_num;
+
+ uint32_t priority_base;
+ uint32_t priority_num;
+
+ uint32_t enable_base;
+ uint32_t enable_num;
+
+ uint32_t threshold_base;
+
+ uint32_t claim_base;
+} IbexPlicState;
+
+#endif /* HW_IBEX_PLIC_H */