hw/misc/mps2_scc: Implement MPS2 Serial Communication Controller

Implement a model of the Serial Communication Controller (SCC) found
in MPS2 FPGA images.

The primary purpose of this device is to communicate with the
Motherboard Configuration Controller (MCC) which is located on
the MPS board itself, outside the FPGA image. This is used
for programming the MPS clock generators. The SCC also has
some basic ID registers and an output for the board LEDs.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1500029487-14822-7-git-send-email-peter.maydell@linaro.org

1 files changed, 310 insertions, 0 deletions

diff --git a/hw/misc/mps2-scc.c b/hw/misc/mps2-scc.c
new file mode 100644
index 0000000..cc58d26
--- /dev/null
+++ b/hw/misc/mps2-scc.c
@@ -0,0 +1,310 @@
+/*
+ * ARM MPS2 SCC emulation
+ *
+ * Copyright (c) 2017 Linaro Limited
+ * Written by Peter Maydell
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 or
+ *  (at your option) any later version.
+ */
+
+/* This is a model of the SCC (Serial Communication Controller)
+ * found in the FPGA images of MPS2 development boards.
+ *
+ * Documentation of it can be found in the MPS2 TRM:
+ * http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100112_0100_03_en/index.html
+ * and also in the Application Notes documenting individual FPGA images.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qapi/error.h"
+#include "trace.h"
+#include "hw/sysbus.h"
+#include "hw/registerfields.h"
+#include "hw/misc/mps2-scc.h"
+
+REG32(CFG0, 0)
+REG32(CFG1, 4)
+REG32(CFG3, 0xc)
+REG32(CFG4, 0x10)
+REG32(CFGDATA_RTN, 0xa0)
+REG32(CFGDATA_OUT, 0xa4)
+REG32(CFGCTRL, 0xa8)
+    FIELD(CFGCTRL, DEVICE, 0, 12)
+    FIELD(CFGCTRL, RES1, 12, 8)
+    FIELD(CFGCTRL, FUNCTION, 20, 6)
+    FIELD(CFGCTRL, RES2, 26, 4)
+    FIELD(CFGCTRL, WRITE, 30, 1)
+    FIELD(CFGCTRL, START, 31, 1)
+REG32(CFGSTAT, 0xac)
+    FIELD(CFGSTAT, DONE, 0, 1)
+    FIELD(CFGSTAT, ERROR, 1, 1)
+REG32(DLL, 0x100)
+REG32(AID, 0xFF8)
+REG32(ID, 0xFFC)
+
+/* Handle a write via the SYS_CFG channel to the specified function/device.
+ * Return false on error (reported to guest via SYS_CFGCTRL ERROR bit).
+ */
+static bool scc_cfg_write(MPS2SCC *s, unsigned function,
+                          unsigned device, uint32_t value)
+{
+    trace_mps2_scc_cfg_write(function, device, value);
+
+    if (function != 1 || device >= NUM_OSCCLK) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "MPS2 SCC config write: bad function %d device %d\n",
+                      function, device);
+        return false;
+    }
+
+    s->oscclk[device] = value;
+    return true;
+}
+
+/* Handle a read via the SYS_CFG channel to the specified function/device.
+ * Return false on error (reported to guest via SYS_CFGCTRL ERROR bit),
+ * or set *value on success.
+ */
+static bool scc_cfg_read(MPS2SCC *s, unsigned function,
+                         unsigned device, uint32_t *value)
+{
+    if (function != 1 || device >= NUM_OSCCLK) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "MPS2 SCC config read: bad function %d device %d\n",
+                      function, device);
+        return false;
+    }
+
+    *value = s->oscclk[device];
+
+    trace_mps2_scc_cfg_read(function, device, *value);
+    return true;
+}
+
+static uint64_t mps2_scc_read(void *opaque, hwaddr offset, unsigned size)
+{
+    MPS2SCC *s = MPS2_SCC(opaque);
+    uint64_t r;
+
+    switch (offset) {
+    case A_CFG0:
+        r = s->cfg0;
+        break;
+    case A_CFG1:
+        r = s->cfg1;
+        break;
+    case A_CFG3:
+        /* These are user-settable DIP switches on the board. We don't
+         * model that, so just return zeroes.
+         */
+        r = 0;
+        break;
+    case A_CFG4:
+        r = s->cfg4;
+        break;
+    case A_CFGDATA_RTN:
+        r = s->cfgdata_rtn;
+        break;
+    case A_CFGDATA_OUT:
+        r = s->cfgdata_out;
+        break;
+    case A_CFGCTRL:
+        r = s->cfgctrl;
+        break;
+    case A_CFGSTAT:
+        r = s->cfgstat;
+        break;
+    case A_DLL:
+        r = s->dll;
+        break;
+    case A_AID:
+        r = s->aid;
+        break;
+    case A_ID:
+        r = s->id;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "MPS2 SCC read: bad offset %x\n", (int) offset);
+        r = 0;
+        break;
+    }
+
+    trace_mps2_scc_read(offset, r, size);
+    return r;
+}
+
+static void mps2_scc_write(void *opaque, hwaddr offset, uint64_t value,
+                           unsigned size)
+{
+    MPS2SCC *s = MPS2_SCC(opaque);
+
+    trace_mps2_scc_write(offset, value, size);
+
+    switch (offset) {
+    case A_CFG0:
+        /* TODO on some boards bit 0 controls RAM remapping */
+        s->cfg0 = value;
+        break;
+    case A_CFG1:
+        /* CFG1 bits [7:0] control the board LEDs. We don't currently have
+         * a mechanism for displaying this graphically, so use a trace event.
+         */
+        trace_mps2_scc_leds(value & 0x80 ? '*' : '.',
+                            value & 0x40 ? '*' : '.',
+                            value & 0x20 ? '*' : '.',
+                            value & 0x10 ? '*' : '.',
+                            value & 0x08 ? '*' : '.',
+                            value & 0x04 ? '*' : '.',
+                            value & 0x02 ? '*' : '.',
+                            value & 0x01 ? '*' : '.');
+        s->cfg1 = value;
+        break;
+    case A_CFGDATA_OUT:
+        s->cfgdata_out = value;
+        break;
+    case A_CFGCTRL:
+        /* Writing to CFGCTRL clears SYS_CFGSTAT */
+        s->cfgstat = 0;
+        s->cfgctrl = value & ~(R_CFGCTRL_RES1_MASK |
+                               R_CFGCTRL_RES2_MASK |
+                               R_CFGCTRL_START_MASK);
+
+        if (value & R_CFGCTRL_START_MASK) {
+            /* Start bit set -- do a read or write (instantaneously) */
+            int device = extract32(s->cfgctrl, R_CFGCTRL_DEVICE_SHIFT,
+                                   R_CFGCTRL_DEVICE_LENGTH);
+            int function = extract32(s->cfgctrl, R_CFGCTRL_FUNCTION_SHIFT,
+                                     R_CFGCTRL_FUNCTION_LENGTH);
+
+            s->cfgstat = R_CFGSTAT_DONE_MASK;
+            if (s->cfgctrl & R_CFGCTRL_WRITE_MASK) {
+                if (!scc_cfg_write(s, function, device, s->cfgdata_out)) {
+                    s->cfgstat |= R_CFGSTAT_ERROR_MASK;
+                }
+            } else {
+                uint32_t result;
+                if (!scc_cfg_read(s, function, device, &result)) {
+                    s->cfgstat |= R_CFGSTAT_ERROR_MASK;
+                } else {
+                    s->cfgdata_rtn = result;
+                }
+            }
+        }
+        break;
+    case A_DLL:
+        /* DLL stands for Digital Locked Loop.
+         * Bits [31:24] (DLL_LOCK_MASK) are writable, and indicate a
+         * mask of which of the DLL_LOCKED bits [16:23] should be ORed
+         * together to determine the ALL_UNMASKED_DLLS_LOCKED bit [0].
+         * For QEMU, our DLLs are always locked, so we can leave bit 0
+         * as 1 always and don't need to recalculate it.
+         */
+        s->dll = deposit32(s->dll, 24, 8, extract32(value, 24, 8));
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "MPS2 SCC write: bad offset 0x%x\n", (int) offset);
+        break;
+    }
+}
+
+static const MemoryRegionOps mps2_scc_ops = {
+    .read = mps2_scc_read,
+    .write = mps2_scc_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static void mps2_scc_reset(DeviceState *dev)
+{
+    MPS2SCC *s = MPS2_SCC(dev);
+    int i;
+
+    trace_mps2_scc_reset();
+    s->cfg0 = 0;
+    s->cfg1 = 0;
+    s->cfgdata_rtn = 0;
+    s->cfgdata_out = 0;
+    s->cfgctrl = 0x100000;
+    s->cfgstat = 0;
+    s->dll = 0xffff0001;
+    for (i = 0; i < NUM_OSCCLK; i++) {
+        s->oscclk[i] = s->oscclk_reset[i];
+    }
+}
+
+static void mps2_scc_init(Object *obj)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+    MPS2SCC *s = MPS2_SCC(obj);
+
+    memory_region_init_io(&s->iomem, obj, &mps2_scc_ops, s, "mps2-scc", 0x1000);
+    sysbus_init_mmio(sbd, &s->iomem);
+}
+
+static void mps2_scc_realize(DeviceState *dev, Error **errp)
+{
+}
+
+static const VMStateDescription mps2_scc_vmstate = {
+    .name = "mps2-scc",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(cfg0, MPS2SCC),
+        VMSTATE_UINT32(cfg1, MPS2SCC),
+        VMSTATE_UINT32(cfgdata_rtn, MPS2SCC),
+        VMSTATE_UINT32(cfgdata_out, MPS2SCC),
+        VMSTATE_UINT32(cfgctrl, MPS2SCC),
+        VMSTATE_UINT32(cfgstat, MPS2SCC),
+        VMSTATE_UINT32(dll, MPS2SCC),
+        VMSTATE_UINT32_ARRAY(oscclk, MPS2SCC, NUM_OSCCLK),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static Property mps2_scc_properties[] = {
+    /* Values for various read-only ID registers (which are specific
+     * to the board model or FPGA image)
+     */
+    DEFINE_PROP_UINT32("scc-cfg4", MPS2SCC, aid, 0),
+    DEFINE_PROP_UINT32("scc-aid", MPS2SCC, aid, 0),
+    DEFINE_PROP_UINT32("scc-id", MPS2SCC, aid, 0),
+    /* These are the initial settings for the source clocks on the board.
+     * In hardware they can be configured via a config file read by the
+     * motherboard configuration controller to suit the FPGA image.
+     * These default values are used by most of the standard FPGA images.
+     */
+    DEFINE_PROP_UINT32("oscclk0", MPS2SCC, oscclk_reset[0], 50000000),
+    DEFINE_PROP_UINT32("oscclk1", MPS2SCC, oscclk_reset[1], 24576000),
+    DEFINE_PROP_UINT32("oscclk2", MPS2SCC, oscclk_reset[2], 25000000),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void mps2_scc_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = mps2_scc_realize;
+    dc->vmsd = &mps2_scc_vmstate;
+    dc->reset = mps2_scc_reset;
+    dc->props = mps2_scc_properties;
+}
+
+static const TypeInfo mps2_scc_info = {
+    .name = TYPE_MPS2_SCC,
+    .parent = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(MPS2SCC),
+    .instance_init = mps2_scc_init,
+    .class_init = mps2_scc_class_init,
+};
+
+static void mps2_scc_register_types(void)
+{
+    type_register_static(&mps2_scc_info);
+}
+
+type_init(mps2_scc_register_types);