SiFive RISC-V PLIC Block

The PLIC (Platform Level Interrupt Controller) device provides a
parameterizable interrupt controller based on SiFive's PLIC specification.

Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Stefan O'Rear <sorear2@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Michael Clark <mjc@sifive.com>

2 files changed, 590 insertions, 0 deletions

diff --git a/hw/riscv/sifive_plic.c b/hw/riscv/sifive_plic.c
new file mode 100644
index 0000000..874de2e
--- /dev/null
+++ b/hw/riscv/sifive_plic.c
@@ -0,0 +1,505 @@
+/*
+ * SiFive PLIC (Platform Level Interrupt Controller)
+ *
+ * Copyright (c) 2017 SiFive, Inc.
+ *
+ * This provides a parameterizable interrupt controller based on SiFive's PLIC.
+ *
+ * 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 "qemu/error-report.h"
+#include "hw/sysbus.h"
+#include "target/riscv/cpu.h"
+#include "hw/riscv/sifive_plic.h"
+
+#define RISCV_DEBUG_PLIC 0
+
+static PLICMode char_to_mode(char c)
+{
+    switch (c) {
+    case 'U': return PLICMode_U;
+    case 'S': return PLICMode_S;
+    case 'H': return PLICMode_H;
+    case 'M': return PLICMode_M;
+    default:
+        error_report("plic: invalid mode '%c'", c);
+        exit(1);
+    }
+}
+
+static char mode_to_char(PLICMode m)
+{
+    switch (m) {
+    case PLICMode_U: return 'U';
+    case PLICMode_S: return 'S';
+    case PLICMode_H: return 'H';
+    case PLICMode_M: return 'M';
+    default: return '?';
+    }
+}
+
+static void sifive_plic_print_state(SiFivePLICState *plic)
+{
+    int i;
+    int addrid;
+
+    /* pending */
+    qemu_log("pending       : ");
+    for (i = plic->bitfield_words - 1; i >= 0; i--) {
+        qemu_log("%08x", plic->pending[i]);
+    }
+    qemu_log("\n");
+
+    /* pending */
+    qemu_log("claimed       : ");
+    for (i = plic->bitfield_words - 1; i >= 0; i--) {
+        qemu_log("%08x", plic->claimed[i]);
+    }
+    qemu_log("\n");
+
+    for (addrid = 0; addrid < plic->num_addrs; addrid++) {
+        qemu_log("hart%d-%c enable: ",
+            plic->addr_config[addrid].hartid,
+            mode_to_char(plic->addr_config[addrid].mode));
+        for (i = plic->bitfield_words - 1; i >= 0; i--) {
+            qemu_log("%08x", plic->enable[addrid * plic->bitfield_words + i]);
+        }
+        qemu_log("\n");
+    }
+}
+
+static
+void sifive_plic_set_pending(SiFivePLICState *plic, int irq, bool pending)
+{
+    qemu_mutex_lock(&plic->lock);
+    uint32_t word = irq >> 5;
+    if (pending) {
+        plic->pending[word] |= (1 << (irq & 31));
+    } else {
+        plic->pending[word] &= ~(1 << (irq & 31));
+    }
+    qemu_mutex_unlock(&plic->lock);
+}
+
+static
+void sifive_plic_set_claimed(SiFivePLICState *plic, int irq, bool claimed)
+{
+    qemu_mutex_lock(&plic->lock);
+    uint32_t word = irq >> 5;
+    if (claimed) {
+        plic->claimed[word] |= (1 << (irq & 31));
+    } else {
+        plic->claimed[word] &= ~(1 << (irq & 31));
+    }
+    qemu_mutex_unlock(&plic->lock);
+}
+
+static
+int sifive_plic_num_irqs_pending(SiFivePLICState *plic, uint32_t addrid)
+{
+    int i, j, count = 0;
+    for (i = 0; i < plic->bitfield_words; i++) {
+        uint32_t pending_enabled_not_claimed =
+            (plic->pending[i] & ~plic->claimed[i]) &
+            plic->enable[addrid * plic->bitfield_words + i];
+        if (!pending_enabled_not_claimed) {
+            continue;
+        }
+        for (j = 0; j < 32; j++) {
+            int irq = (i << 5) + j;
+            uint32_t prio = plic->source_priority[irq];
+            int enabled = pending_enabled_not_claimed & (1 << j);
+            if (enabled && prio > plic->target_priority[addrid]) {
+                count++;
+            }
+        }
+    }
+    return count;
+}
+
+static void sifive_plic_update(SiFivePLICState *plic)
+{
+    int addrid;
+
+    /* raise irq on harts where this irq is enabled */
+    for (addrid = 0; addrid < plic->num_addrs; addrid++) {
+        uint32_t hartid = plic->addr_config[addrid].hartid;
+        PLICMode mode = plic->addr_config[addrid].mode;
+        CPUState *cpu = qemu_get_cpu(hartid);
+        CPURISCVState *env = cpu ? cpu->env_ptr : NULL;
+        if (!env) {
+            continue;
+        }
+        int level = sifive_plic_num_irqs_pending(plic, addrid) > 0;
+        switch (mode) {
+        case PLICMode_M:
+            riscv_set_local_interrupt(RISCV_CPU(cpu), MIP_MEIP, level);
+            break;
+        case PLICMode_S:
+            riscv_set_local_interrupt(RISCV_CPU(cpu), MIP_SEIP, level);
+            break;
+        default:
+            break;
+        }
+    }
+
+    if (RISCV_DEBUG_PLIC) {
+        sifive_plic_print_state(plic);
+    }
+}
+
+void sifive_plic_raise_irq(SiFivePLICState *plic, uint32_t irq)
+{
+    sifive_plic_set_pending(plic, irq, true);
+    sifive_plic_update(plic);
+}
+
+void sifive_plic_lower_irq(SiFivePLICState *plic, uint32_t irq)
+{
+    sifive_plic_set_pending(plic, irq, false);
+    sifive_plic_update(plic);
+}
+
+static uint32_t sifive_plic_claim(SiFivePLICState *plic, uint32_t addrid)
+{
+    int i, j;
+    for (i = 0; i < plic->bitfield_words; i++) {
+        uint32_t pending_enabled_not_claimed =
+            (plic->pending[i] & ~plic->claimed[i]) &
+            plic->enable[addrid * plic->bitfield_words + i];
+        if (!pending_enabled_not_claimed) {
+            continue;
+        }
+        for (j = 0; j < 32; j++) {
+            int irq = (i << 5) + j;
+            uint32_t prio = plic->source_priority[irq];
+            int enabled = pending_enabled_not_claimed & (1 << j);
+            if (enabled && prio > plic->target_priority[addrid]) {
+                sifive_plic_set_pending(plic, irq, false);
+                sifive_plic_set_claimed(plic, irq, true);
+                return irq;
+            }
+        }
+    }
+    return 0;
+}
+
+static uint64_t sifive_plic_read(void *opaque, hwaddr addr, unsigned size)
+{
+    SiFivePLICState *plic = opaque;
+
+    /* writes must be 4 byte words */
+    if ((addr & 0x3) != 0) {
+        goto err;
+    }
+
+    if (addr >= plic->priority_base && /* 4 bytes per source */
+        addr < plic->priority_base + (plic->num_sources << 2))
+    {
+        uint32_t irq = (addr - plic->priority_base) >> 2;
+        if (RISCV_DEBUG_PLIC) {
+            qemu_log("plic: read priority: irq=%d priority=%d\n",
+                irq, plic->source_priority[irq]);
+        }
+        return plic->source_priority[irq];
+    } else if (addr >= plic->pending_base && /* 1 bit per source */
+               addr < plic->pending_base + (plic->num_sources >> 3))
+    {
+        uint32_t word = (addr - plic->priority_base) >> 2;
+        if (RISCV_DEBUG_PLIC) {
+            qemu_log("plic: read pending: word=%d value=%d\n",
+                word, plic->pending[word]);
+        }
+        return plic->pending[word];
+    } else if (addr >= plic->enable_base && /* 1 bit per source */
+             addr < plic->enable_base + plic->num_addrs * plic->enable_stride)
+    {
+        uint32_t addrid = (addr - plic->enable_base) / plic->enable_stride;
+        uint32_t wordid = (addr & (plic->enable_stride - 1)) >> 2;
+        if (wordid < plic->bitfield_words) {
+            if (RISCV_DEBUG_PLIC) {
+                qemu_log("plic: read enable: hart%d-%c word=%d value=%x\n",
+                    plic->addr_config[addrid].hartid,
+                    mode_to_char(plic->addr_config[addrid].mode), wordid,
+                    plic->enable[addrid * plic->bitfield_words + wordid]);
+            }
+            return plic->enable[addrid * plic->bitfield_words + wordid];
+        }
+    } else if (addr >= plic->context_base && /* 1 bit per source */
+             addr < plic->context_base + plic->num_addrs * plic->context_stride)
+    {
+        uint32_t addrid = (addr - plic->context_base) / plic->context_stride;
+        uint32_t contextid = (addr & (plic->context_stride - 1));
+        if (contextid == 0) {
+            if (RISCV_DEBUG_PLIC) {
+                qemu_log("plic: read priority: hart%d-%c priority=%x\n",
+                    plic->addr_config[addrid].hartid,
+                    mode_to_char(plic->addr_config[addrid].mode),
+                    plic->target_priority[addrid]);
+            }
+            return plic->target_priority[addrid];
+        } else if (contextid == 4) {
+            uint32_t value = sifive_plic_claim(plic, addrid);
+            if (RISCV_DEBUG_PLIC) {
+                qemu_log("plic: read claim: hart%d-%c irq=%x\n",
+                    plic->addr_config[addrid].hartid,
+                    mode_to_char(plic->addr_config[addrid].mode),
+                    value);
+                sifive_plic_print_state(plic);
+            }
+            return value;
+        }
+    }
+
+err:
+    error_report("plic: invalid register read: %08x", (uint32_t)addr);
+    return 0;
+}
+
+static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
+        unsigned size)
+{
+    SiFivePLICState *plic = opaque;
+
+    /* writes must be 4 byte words */
+    if ((addr & 0x3) != 0) {
+        goto err;
+    }
+
+    if (addr >= plic->priority_base && /* 4 bytes per source */
+        addr < plic->priority_base + (plic->num_sources << 2))
+    {
+        uint32_t irq = (addr - plic->priority_base) >> 2;
+        plic->source_priority[irq] = value & 7;
+        if (RISCV_DEBUG_PLIC) {
+            qemu_log("plic: write priority: irq=%d priority=%d\n",
+                irq, plic->source_priority[irq]);
+        }
+        return;
+    } else if (addr >= plic->pending_base && /* 1 bit per source */
+               addr < plic->pending_base + (plic->num_sources >> 3))
+    {
+        error_report("plic: invalid pending write: %08x", (uint32_t)addr);
+        return;
+    } else if (addr >= plic->enable_base && /* 1 bit per source */
+        addr < plic->enable_base + plic->num_addrs * plic->enable_stride)
+    {
+        uint32_t addrid = (addr - plic->enable_base) / plic->enable_stride;
+        uint32_t wordid = (addr & (plic->enable_stride - 1)) >> 2;
+        if (wordid < plic->bitfield_words) {
+            plic->enable[addrid * plic->bitfield_words + wordid] = value;
+            if (RISCV_DEBUG_PLIC) {
+                qemu_log("plic: write enable: hart%d-%c word=%d value=%x\n",
+                    plic->addr_config[addrid].hartid,
+                    mode_to_char(plic->addr_config[addrid].mode), wordid,
+                    plic->enable[addrid * plic->bitfield_words + wordid]);
+            }
+            return;
+        }
+    } else if (addr >= plic->context_base && /* 4 bytes per reg */
+        addr < plic->context_base + plic->num_addrs * plic->context_stride)
+    {
+        uint32_t addrid = (addr - plic->context_base) / plic->context_stride;
+        uint32_t contextid = (addr & (plic->context_stride - 1));
+        if (contextid == 0) {
+            if (RISCV_DEBUG_PLIC) {
+                qemu_log("plic: write priority: hart%d-%c priority=%x\n",
+                    plic->addr_config[addrid].hartid,
+                    mode_to_char(plic->addr_config[addrid].mode),
+                    plic->target_priority[addrid]);
+            }
+            if (value <= plic->num_priorities) {
+                plic->target_priority[addrid] = value;
+                sifive_plic_update(plic);
+            }
+            return;
+        } else if (contextid == 4) {
+            if (RISCV_DEBUG_PLIC) {
+                qemu_log("plic: write claim: hart%d-%c irq=%x\n",
+                    plic->addr_config[addrid].hartid,
+                    mode_to_char(plic->addr_config[addrid].mode),
+                    (uint32_t)value);
+            }
+            if (value < plic->num_sources) {
+                sifive_plic_set_claimed(plic, value, false);
+                sifive_plic_update(plic);
+            }
+            return;
+        }
+    }
+
+err:
+    error_report("plic: invalid register write: %08x", (uint32_t)addr);
+}
+
+static const MemoryRegionOps sifive_plic_ops = {
+    .read = sifive_plic_read,
+    .write = sifive_plic_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4
+    }
+};
+
+static Property sifive_plic_properties[] = {
+    DEFINE_PROP_STRING("hart-config", SiFivePLICState, hart_config),
+    DEFINE_PROP_UINT32("num-sources", SiFivePLICState, num_sources, 0),
+    DEFINE_PROP_UINT32("num-priorities", SiFivePLICState, num_priorities, 0),
+    DEFINE_PROP_UINT32("priority-base", SiFivePLICState, priority_base, 0),
+    DEFINE_PROP_UINT32("pending-base", SiFivePLICState, pending_base, 0),
+    DEFINE_PROP_UINT32("enable-base", SiFivePLICState, enable_base, 0),
+    DEFINE_PROP_UINT32("enable-stride", SiFivePLICState, enable_stride, 0),
+    DEFINE_PROP_UINT32("context-base", SiFivePLICState, context_base, 0),
+    DEFINE_PROP_UINT32("context-stride", SiFivePLICState, context_stride, 0),
+    DEFINE_PROP_UINT32("aperture-size", SiFivePLICState, aperture_size, 0),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+/*
+ * parse PLIC hart/mode address offset config
+ *
+ * "M"              1 hart with M mode
+ * "MS,MS"          2 harts, 0-1 with M and S mode
+ * "M,MS,MS,MS,MS"  5 harts, 0 with M mode, 1-5 with M and S mode
+ */
+static void parse_hart_config(SiFivePLICState *plic)
+{
+    int addrid, hartid, modes;
+    const char *p;
+    char c;
+
+    /* count and validate hart/mode combinations */
+    addrid = 0, hartid = 0, modes = 0;
+    p = plic->hart_config;
+    while ((c = *p++)) {
+        if (c == ',') {
+            addrid += __builtin_popcount(modes);
+            modes = 0;
+            hartid++;
+        } else {
+            int m = 1 << char_to_mode(c);
+            if (modes == (modes | m)) {
+                error_report("plic: duplicate mode '%c' in config: %s",
+                             c, plic->hart_config);
+                exit(1);
+            }
+            modes |= m;
+        }
+    }
+    if (modes) {
+        addrid += __builtin_popcount(modes);
+    }
+    hartid++;
+
+    /* store hart/mode combinations */
+    plic->num_addrs = addrid;
+    plic->addr_config = g_new(PLICAddr, plic->num_addrs);
+    addrid = 0, hartid = 0;
+    p = plic->hart_config;
+    while ((c = *p++)) {
+        if (c == ',') {
+            hartid++;
+        } else {
+            plic->addr_config[addrid].addrid = addrid;
+            plic->addr_config[addrid].hartid = hartid;
+            plic->addr_config[addrid].mode = char_to_mode(c);
+            addrid++;
+        }
+    }
+}
+
+static void sifive_plic_irq_request(void *opaque, int irq, int level)
+{
+    SiFivePLICState *plic = opaque;
+    if (RISCV_DEBUG_PLIC) {
+        qemu_log("sifive_plic_irq_request: irq=%d level=%d\n", irq, level);
+    }
+    sifive_plic_set_pending(plic, irq, level > 0);
+    sifive_plic_update(plic);
+}
+
+static void sifive_plic_realize(DeviceState *dev, Error **errp)
+{
+    SiFivePLICState *plic = SIFIVE_PLIC(dev);
+    int i;
+
+    memory_region_init_io(&plic->mmio, OBJECT(dev), &sifive_plic_ops, plic,
+                          TYPE_SIFIVE_PLIC, plic->aperture_size);
+    parse_hart_config(plic);
+    qemu_mutex_init(&plic->lock);
+    plic->bitfield_words = (plic->num_sources + 31) >> 5;
+    plic->source_priority = g_new0(uint32_t, plic->num_sources);
+    plic->target_priority = g_new(uint32_t, plic->num_addrs);
+    plic->pending = g_new0(uint32_t, plic->bitfield_words);
+    plic->claimed = g_new0(uint32_t, plic->bitfield_words);
+    plic->enable = g_new0(uint32_t, plic->bitfield_words * plic->num_addrs);
+    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &plic->mmio);
+    plic->irqs = g_new0(qemu_irq, plic->num_sources + 1);
+    for (i = 0; i <= plic->num_sources; i++) {
+        plic->irqs[i] = qemu_allocate_irq(sifive_plic_irq_request, plic, i);
+    }
+}
+
+static void sifive_plic_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = sifive_plic_properties;
+    dc->realize = sifive_plic_realize;
+}
+
+static const TypeInfo sifive_plic_info = {
+    .name          = TYPE_SIFIVE_PLIC,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(SiFivePLICState),
+    .class_init    = sifive_plic_class_init,
+};
+
+static void sifive_plic_register_types(void)
+{
+    type_register_static(&sifive_plic_info);
+}
+
+type_init(sifive_plic_register_types)
+
+/*
+ * Create PLIC device.
+ */
+DeviceState *sifive_plic_create(hwaddr addr, char *hart_config,
+    uint32_t num_sources, uint32_t num_priorities,
+    uint32_t priority_base, uint32_t pending_base,
+    uint32_t enable_base, uint32_t enable_stride,
+    uint32_t context_base, uint32_t context_stride,
+    uint32_t aperture_size)
+{
+    DeviceState *dev = qdev_create(NULL, TYPE_SIFIVE_PLIC);
+    assert(enable_stride == (enable_stride & -enable_stride));
+    assert(context_stride == (context_stride & -context_stride));
+    qdev_prop_set_string(dev, "hart-config", hart_config);
+    qdev_prop_set_uint32(dev, "num-sources", num_sources);
+    qdev_prop_set_uint32(dev, "num-priorities", num_priorities);
+    qdev_prop_set_uint32(dev, "priority-base", priority_base);
+    qdev_prop_set_uint32(dev, "pending-base", pending_base);
+    qdev_prop_set_uint32(dev, "enable-base", enable_base);
+    qdev_prop_set_uint32(dev, "enable-stride", enable_stride);
+    qdev_prop_set_uint32(dev, "context-base", context_base);
+    qdev_prop_set_uint32(dev, "context-stride", context_stride);
+    qdev_prop_set_uint32(dev, "aperture-size", aperture_size);
+    qdev_init_nofail(dev);
+    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, addr);
+    return dev;
+}
diff --git a/include/hw/riscv/sifive_plic.h b/include/hw/riscv/sifive_plic.h
new file mode 100644
index 0000000..11a5a98
--- /dev/null
+++ b/include/hw/riscv/sifive_plic.h
@@ -0,0 +1,85 @@
+/*
+ * SiFive PLIC (Platform Level Interrupt Controller) interface
+ *
+ * Copyright (c) 2017 SiFive, Inc.
+ *
+ * This provides a RISC-V PLIC device
+ *
+ * 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_SIFIVE_PLIC_H
+#define HW_SIFIVE_PLIC_H
+
+#include "hw/irq.h"
+
+#define TYPE_SIFIVE_PLIC "riscv.sifive.plic"
+
+#define SIFIVE_PLIC(obj) \
+    OBJECT_CHECK(SiFivePLICState, (obj), TYPE_SIFIVE_PLIC)
+
+typedef enum PLICMode {
+    PLICMode_U,
+    PLICMode_S,
+    PLICMode_H,
+    PLICMode_M
+} PLICMode;
+
+typedef struct PLICAddr {
+    uint32_t addrid;
+    uint32_t hartid;
+    PLICMode mode;
+} PLICAddr;
+
+typedef struct SiFivePLICState {
+    /*< private >*/
+    SysBusDevice parent_obj;
+
+    /*< public >*/
+    MemoryRegion mmio;
+    uint32_t num_addrs;
+    uint32_t bitfield_words;
+    PLICAddr *addr_config;
+    uint32_t *source_priority;
+    uint32_t *target_priority;
+    uint32_t *pending;
+    uint32_t *claimed;
+    uint32_t *enable;
+    QemuMutex lock;
+    qemu_irq *irqs;
+
+    /* config */
+    char *hart_config;
+    uint32_t num_sources;
+    uint32_t num_priorities;
+    uint32_t priority_base;
+    uint32_t pending_base;
+    uint32_t enable_base;
+    uint32_t enable_stride;
+    uint32_t context_base;
+    uint32_t context_stride;
+    uint32_t aperture_size;
+} SiFivePLICState;
+
+void sifive_plic_raise_irq(SiFivePLICState *plic, uint32_t irq);
+void sifive_plic_lower_irq(SiFivePLICState *plic, uint32_t irq);
+
+DeviceState *sifive_plic_create(hwaddr addr, char *hart_config,
+    uint32_t num_sources, uint32_t num_priorities,
+    uint32_t priority_base, uint32_t pending_base,
+    uint32_t enable_base, uint32_t enable_stride,
+    uint32_t context_base, uint32_t context_stride,
+    uint32_t aperture_size);
+
+#endif
+