lm32: add Milkymist PFPU support

This patch adds support for Milkymist's Programmable FPU.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>

3 files changed, 543 insertions, 0 deletions

diff --git a/Makefile.target b/Makefile.target
index 6fd8a1711..0a87446f1 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -271,6 +271,7 @@ obj-lm32-y += milkymist-ac97.o
 obj-lm32-y += milkymist-hpdmc.o
 obj-lm32-y += milkymist-memcard.o
 obj-lm32-y += milkymist-minimac.o
+obj-lm32-y += milkymist-pfpu.o
 
 obj-mips-y = mips_r4k.o mips_jazz.o mips_malta.o mips_mipssim.o
 obj-mips-y += mips_addr.o mips_timer.o mips_int.o
diff --git a/hw/milkymist-pfpu.c b/hw/milkymist-pfpu.c
new file mode 100644
index 000000000..4831e00b8
--- /dev/null
+++ b/hw/milkymist-pfpu.c
@@ -0,0 +1,536 @@
+/*
+ *  QEMU model of the Milkymist programmable FPU.
+ *
+ *  Copyright (c) 2010 Michael Walle <michael@walle.cc>
+ *
+ * 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/>.
+ *
+ *
+ * Specification available at:
+ *   http://www.milkymist.org/socdoc/pfpu.pdf
+ *
+ */
+
+#include "hw.h"
+#include "sysbus.h"
+#include "trace.h"
+#include "qemu-log.h"
+#include "qemu-error.h"
+#include <math.h>
+
+/* #define TRACE_EXEC */
+
+#ifdef TRACE_EXEC
+#    define D_EXEC(x) x
+#else
+#    define D_EXEC(x)
+#endif
+
+enum {
+    R_CTL = 0,
+    R_MESHBASE,
+    R_HMESHLAST,
+    R_VMESHLAST,
+    R_CODEPAGE,
+    R_VERTICES,
+    R_COLLISIONS,
+    R_STRAYWRITES,
+    R_LASTDMA,
+    R_PC,
+    R_DREGBASE,
+    R_CODEBASE,
+    R_MAX
+};
+
+enum {
+    CTL_START_BUSY = (1<<0),
+};
+
+enum {
+    OP_NOP = 0,
+    OP_FADD,
+    OP_FSUB,
+    OP_FMUL,
+    OP_FABS,
+    OP_F2I,
+    OP_I2F,
+    OP_VECTOUT,
+    OP_SIN,
+    OP_COS,
+    OP_ABOVE,
+    OP_EQUAL,
+    OP_COPY,
+    OP_IF,
+    OP_TSIGN,
+    OP_QUAKE,
+};
+
+enum {
+    GPR_X = 0,
+    GPR_Y = 1,
+    GPR_FLAGS = 2,
+};
+
+enum {
+    LATENCY_FADD = 5,
+    LATENCY_FSUB = 5,
+    LATENCY_FMUL = 7,
+    LATENCY_FABS = 2,
+    LATENCY_F2I = 2,
+    LATENCY_I2F = 3,
+    LATENCY_VECTOUT = 0,
+    LATENCY_SIN = 4,
+    LATENCY_COS = 4,
+    LATENCY_ABOVE = 2,
+    LATENCY_EQUAL = 2,
+    LATENCY_COPY = 2,
+    LATENCY_IF = 2,
+    LATENCY_TSIGN = 2,
+    LATENCY_QUAKE = 2,
+    MAX_LATENCY = 7
+};
+
+#define GPR_BEGIN       0x100
+#define GPR_END         0x17f
+#define MICROCODE_BEGIN 0x200
+#define MICROCODE_END   0x3ff
+#define MICROCODE_WORDS 2048
+
+#define REINTERPRET_CAST(type, val) (*((type *)&(val)))
+
+#ifdef TRACE_EXEC
+static const char *opcode_to_str[] = {
+    "NOP", "FADD", "FSUB", "FMUL", "FABS", "F2I", "I2F", "VECTOUT",
+    "SIN", "COS", "ABOVE", "EQUAL", "COPY", "IF", "TSIGN", "QUAKE",
+};
+#endif
+
+struct MilkymistPFPUState {
+    SysBusDevice busdev;
+    CharDriverState *chr;
+    qemu_irq irq;
+
+    uint32_t regs[R_MAX];
+    uint32_t gp_regs[128];
+    uint32_t microcode[MICROCODE_WORDS];
+
+    int output_queue_pos;
+    uint32_t output_queue[MAX_LATENCY];
+};
+typedef struct MilkymistPFPUState MilkymistPFPUState;
+
+static inline target_phys_addr_t
+get_dma_address(uint32_t base, uint32_t x, uint32_t y)
+{
+    return base + 8 * (128 * y + x);
+}
+
+static inline void
+output_queue_insert(MilkymistPFPUState *s, uint32_t val, int pos)
+{
+    s->output_queue[(s->output_queue_pos + pos) % MAX_LATENCY] = val;
+}
+
+static inline uint32_t
+output_queue_remove(MilkymistPFPUState *s)
+{
+    return s->output_queue[s->output_queue_pos];
+}
+
+static inline void
+output_queue_advance(MilkymistPFPUState *s)
+{
+    s->output_queue[s->output_queue_pos] = 0;
+    s->output_queue_pos = (s->output_queue_pos + 1) % MAX_LATENCY;
+}
+
+static int pfpu_decode_insn(MilkymistPFPUState *s)
+{
+    uint32_t pc = s->regs[R_PC];
+    uint32_t insn = s->microcode[pc];
+    uint32_t reg_a = (insn >> 18) & 0x7f;
+    uint32_t reg_b = (insn >> 11) & 0x7f;
+    uint32_t op = (insn >> 7) & 0xf;
+    uint32_t reg_d = insn & 0x7f;
+    uint32_t r;
+    int latency = 0;
+
+    switch (op) {
+    case OP_NOP:
+        break;
+    case OP_FADD:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        float t = a + b;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_FADD;
+        D_EXEC(qemu_log("ADD a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
+    } break;
+    case OP_FSUB:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        float t = a - b;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_FSUB;
+        D_EXEC(qemu_log("SUB a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
+    } break;
+    case OP_FMUL:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        float t = a * b;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_FMUL;
+        D_EXEC(qemu_log("MUL a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
+    } break;
+    case OP_FABS:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float t = fabsf(a);
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_FABS;
+        D_EXEC(qemu_log("ABS a=%f t=%f, r=%08x\n", a, t, r));
+    } break;
+    case OP_F2I:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        int32_t t = a;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_F2I;
+        D_EXEC(qemu_log("F2I a=%f t=%d, r=%08x\n", a, t, r));
+    } break;
+    case OP_I2F:
+    {
+        int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]);
+        float t = a;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_I2F;
+        D_EXEC(qemu_log("I2F a=%08x t=%f, r=%08x\n", a, t, r));
+    } break;
+    case OP_VECTOUT:
+    {
+        uint32_t a = cpu_to_be32(s->gp_regs[reg_a]);
+        uint32_t b = cpu_to_be32(s->gp_regs[reg_b]);
+        target_phys_addr_t dma_ptr =
+            get_dma_address(s->regs[R_MESHBASE],
+                    s->gp_regs[GPR_X], s->gp_regs[GPR_Y]);
+        cpu_physical_memory_write(dma_ptr, (uint8_t *)&a, 4);
+        cpu_physical_memory_write(dma_ptr + 4, (uint8_t *)&b, 4);
+        s->regs[R_LASTDMA] = dma_ptr + 4;
+        D_EXEC(qemu_log("VECTOUT a=%08x b=%08x dma=%08x\n", a, b, dma_ptr));
+        trace_milkymist_pfpu_vectout(a, b, dma_ptr);
+    } break;
+    case OP_SIN:
+    {
+        int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]);
+        float t = sinf(a * (1.0f / (M_PI * 4096.0f)));
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_SIN;
+        D_EXEC(qemu_log("SIN a=%d t=%f, r=%08x\n", a, t, r));
+    } break;
+    case OP_COS:
+    {
+        int32_t a = REINTERPRET_CAST(int32_t, s->gp_regs[reg_a]);
+        float t = cosf(a * (1.0f / (M_PI * 4096.0f)));
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_COS;
+        D_EXEC(qemu_log("COS a=%d t=%f, r=%08x\n", a, t, r));
+    } break;
+    case OP_ABOVE:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        float t = (a > b) ? 1.0f : 0.0f;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_ABOVE;
+        D_EXEC(qemu_log("ABOVE a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
+    } break;
+    case OP_EQUAL:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        float t = (a == b) ? 1.0f : 0.0f;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_EQUAL;
+        D_EXEC(qemu_log("EQUAL a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
+    } break;
+    case OP_COPY:
+    {
+        r = s->gp_regs[reg_a];
+        latency = LATENCY_COPY;
+        D_EXEC(qemu_log("COPY"));
+    } break;
+    case OP_IF:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        uint32_t f = s->gp_regs[GPR_FLAGS];
+        float t = (f != 0) ? a : b;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_IF;
+        D_EXEC(qemu_log("IF f=%u a=%f b=%f t=%f, r=%08x\n", f, a, b, t, r));
+    } break;
+    case OP_TSIGN:
+    {
+        float a = REINTERPRET_CAST(float, s->gp_regs[reg_a]);
+        float b = REINTERPRET_CAST(float, s->gp_regs[reg_b]);
+        float t = (b < 0) ? -a : a;
+        r = REINTERPRET_CAST(uint32_t, t);
+        latency = LATENCY_TSIGN;
+        D_EXEC(qemu_log("TSIGN a=%f b=%f t=%f, r=%08x\n", a, b, t, r));
+    } break;
+    case OP_QUAKE:
+    {
+        uint32_t a = s->gp_regs[reg_a];
+        r = 0x5f3759df - (a >> 1);
+        latency = LATENCY_QUAKE;
+        D_EXEC(qemu_log("QUAKE a=%d r=%08x\n", a, r));
+    } break;
+
+    default:
+        error_report("milkymist_pfpu: unknown opcode %d\n", op);
+        break;
+    }
+
+    if (!reg_d) {
+        D_EXEC(qemu_log("%04d %8s R%03d, R%03d <L=%d, E=%04d>\n",
+                    s->regs[R_PC], opcode_to_str[op], reg_a, reg_b, latency,
+                    s->regs[R_PC] + latency));
+    } else {
+        D_EXEC(qemu_log("%04d %8s R%03d, R%03d <L=%d, E=%04d> -> R%03d\n",
+                    s->regs[R_PC], opcode_to_str[op], reg_a, reg_b, latency,
+                    s->regs[R_PC] + latency, reg_d));
+    }
+
+    if (op == OP_VECTOUT) {
+        return 0;
+    }
+
+    /* store output for this cycle */
+    if (reg_d) {
+        uint32_t val = output_queue_remove(s);
+        D_EXEC(qemu_log("R%03d <- 0x%08x\n", reg_d, val));
+        s->gp_regs[reg_d] = val;
+    }
+
+    output_queue_advance(s);
+
+    /* store op output */
+    if (op != OP_NOP) {
+        output_queue_insert(s, r, latency-1);
+    }
+
+    /* advance PC */
+    s->regs[R_PC]++;
+
+    return 1;
+};
+
+static void pfpu_start(MilkymistPFPUState *s)
+{
+    int x, y;
+    int i;
+
+    for (y = 0; y <= s->regs[R_VMESHLAST]; y++) {
+        for (x = 0; x <= s->regs[R_HMESHLAST]; x++) {
+            D_EXEC(qemu_log("\nprocessing x=%d y=%d\n", x, y));
+
+            /* set current position */
+            s->gp_regs[GPR_X] = x;
+            s->gp_regs[GPR_Y] = y;
+
+            /* run microcode on this position */
+            i = 0;
+            while (pfpu_decode_insn(s)) {
+                /* decode at most MICROCODE_WORDS instructions */
+                if (i++ >= MICROCODE_WORDS) {
+                    error_report("milkymist_pfpu: too many instructions "
+                            "executed in microcode. No VECTOUT?\n");
+                    break;
+                }
+            }
+
+            /* reset pc for next run */
+            s->regs[R_PC] = 0;
+        }
+    }
+
+    s->regs[R_VERTICES] = x * y;
+
+    trace_milkymist_pfpu_pulse_irq();
+    qemu_irq_pulse(s->irq);
+}
+
+static inline int get_microcode_address(MilkymistPFPUState *s, uint32_t addr)
+{
+    return (512 * s->regs[R_CODEPAGE]) + addr - MICROCODE_BEGIN;
+}
+
+static uint32_t pfpu_read(void *opaque, target_phys_addr_t addr)
+{
+    MilkymistPFPUState *s = opaque;
+    uint32_t r = 0;
+
+    addr >>= 2;
+    switch (addr) {
+    case R_CTL:
+    case R_MESHBASE:
+    case R_HMESHLAST:
+    case R_VMESHLAST:
+    case R_CODEPAGE:
+    case R_VERTICES:
+    case R_COLLISIONS:
+    case R_STRAYWRITES:
+    case R_LASTDMA:
+    case R_PC:
+    case R_DREGBASE:
+    case R_CODEBASE:
+        r = s->regs[addr];
+        break;
+    case GPR_BEGIN ... GPR_END:
+        r = s->gp_regs[addr - GPR_BEGIN];
+        break;
+    case MICROCODE_BEGIN ...  MICROCODE_END:
+        r = s->microcode[get_microcode_address(s, addr)];
+        break;
+
+    default:
+        error_report("milkymist_pfpu: read access to unknown register 0x"
+                TARGET_FMT_plx, addr << 2);
+        break;
+    }
+
+    trace_milkymist_pfpu_memory_read(addr << 2, r);
+
+    return r;
+}
+
+static void
+pfpu_write(void *opaque, target_phys_addr_t addr, uint32_t value)
+{
+    MilkymistPFPUState *s = opaque;
+
+    trace_milkymist_pfpu_memory_write(addr, value);
+
+    addr >>= 2;
+    switch (addr) {
+    case R_CTL:
+        if (value & CTL_START_BUSY) {
+            pfpu_start(s);
+        }
+        break;
+    case R_MESHBASE:
+    case R_HMESHLAST:
+    case R_VMESHLAST:
+    case R_CODEPAGE:
+    case R_VERTICES:
+    case R_COLLISIONS:
+    case R_STRAYWRITES:
+    case R_LASTDMA:
+    case R_PC:
+    case R_DREGBASE:
+    case R_CODEBASE:
+        s->regs[addr] = value;
+        break;
+    case GPR_BEGIN ...  GPR_END:
+        s->gp_regs[addr - GPR_BEGIN] = value;
+        break;
+    case MICROCODE_BEGIN ...  MICROCODE_END:
+        s->microcode[get_microcode_address(s, addr)] = value;
+        break;
+
+    default:
+        error_report("milkymist_pfpu: write access to unknown register 0x"
+                TARGET_FMT_plx, addr << 2);
+        break;
+    }
+}
+
+static CPUReadMemoryFunc * const pfpu_read_fn[] = {
+    NULL,
+    NULL,
+    &pfpu_read,
+};
+
+static CPUWriteMemoryFunc * const pfpu_write_fn[] = {
+    NULL,
+    NULL,
+    &pfpu_write,
+};
+
+static void milkymist_pfpu_reset(DeviceState *d)
+{
+    MilkymistPFPUState *s = container_of(d, MilkymistPFPUState, busdev.qdev);
+    int i;
+
+    for (i = 0; i < R_MAX; i++) {
+        s->regs[i] = 0;
+    }
+    for (i = 0; i < 128; i++) {
+        s->gp_regs[i] = 0;
+    }
+    for (i = 0; i < MICROCODE_WORDS; i++) {
+        s->microcode[i] = 0;
+    }
+    s->output_queue_pos = 0;
+    for (i = 0; i < MAX_LATENCY; i++) {
+        s->output_queue[i] = 0;
+    }
+}
+
+static int milkymist_pfpu_init(SysBusDevice *dev)
+{
+    MilkymistPFPUState *s = FROM_SYSBUS(typeof(*s), dev);
+    int pfpu_regs;
+
+    sysbus_init_irq(dev, &s->irq);
+
+    pfpu_regs = cpu_register_io_memory(pfpu_read_fn, pfpu_write_fn, s,
+            DEVICE_NATIVE_ENDIAN);
+    sysbus_init_mmio(dev, MICROCODE_END * 4, pfpu_regs);
+
+    return 0;
+}
+
+static const VMStateDescription vmstate_milkymist_pfpu = {
+    .name = "milkymist-pfpu",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField[]) {
+        VMSTATE_UINT32_ARRAY(regs, MilkymistPFPUState, R_MAX),
+        VMSTATE_UINT32_ARRAY(gp_regs, MilkymistPFPUState, 128),
+        VMSTATE_UINT32_ARRAY(microcode, MilkymistPFPUState, MICROCODE_WORDS),
+        VMSTATE_INT32(output_queue_pos, MilkymistPFPUState),
+        VMSTATE_UINT32_ARRAY(output_queue, MilkymistPFPUState, MAX_LATENCY),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static SysBusDeviceInfo milkymist_pfpu_info = {
+    .init = milkymist_pfpu_init,
+    .qdev.name  = "milkymist-pfpu",
+    .qdev.size  = sizeof(MilkymistPFPUState),
+    .qdev.vmsd  = &vmstate_milkymist_pfpu,
+    .qdev.reset = milkymist_pfpu_reset,
+};
+
+static void milkymist_pfpu_register(void)
+{
+    sysbus_register_withprop(&milkymist_pfpu_info);
+}
+
+device_init(milkymist_pfpu_register)
diff --git a/trace-events b/trace-events
index 2becf85af..b3fa971d2 100644
--- a/trace-events
+++ b/trace-events
@@ -318,3 +318,9 @@ disable milkymist_minimac_drop_rx_frame(const void *buf) "buf %p"
 disable milkymist_minimac_rx_transfer(const void *buf, uint32_t length) "buf %p length %d"
 disable milkymist_minimac_pulse_irq_rx(void) "Pulse IRQ RX"
 disable milkymist_minimac_pulse_irq_tx(void) "Pulse IRQ TX"
+
+# hw/milkymist-pfpu.c
+disable milkymist_pfpu_memory_read(uint32_t addr, uint32_t value) "addr %08x value %08x"
+disable milkymist_pfpu_memory_write(uint32_t addr, uint32_t value) "addr %08x value %08x"
+disable milkymist_pfpu_vectout(uint32_t a, uint32_t b, uint32_t dma_ptr) "a %08x b %08x dma_ptr %08x"
+disable milkymist_pfpu_pulse_irq(void) "Pulse IRQ"