hw/mem: Stubbed out NPCM7xx Memory Controller model

This just implements the bare minimum to cause the boot block to skip
memory initialization.

Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Message-id: 20200911052101.2602693-10-hskinnemoen@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/npcm7xx.c

@@ -43,6 +43,7 @@
 #define NPCM7XX_CPUP_BA         (0xf03fe000)
 #define NPCM7XX_GCR_BA          (0xf0800000)
 #define NPCM7XX_CLK_BA          (0xf0801000)
+#define NPCM7XX_MC_BA           (0xf0824000)
 
 /* Internal AHB SRAM */
 #define NPCM7XX_RAM3_BA         (0xc0008000)
@@ -186,6 +187,7 @@ static void npcm7xx_init(Object *obj)
                             TYPE_NPCM7XX_KEY_STORAGE);
     object_initialize_child(obj, "otp2", &s->fuse_array,
                             TYPE_NPCM7XX_FUSE_ARRAY);
+    object_initialize_child(obj, "mc", &s->mc, TYPE_NPCM7XX_MC);
 
     for (i = 0; i < ARRAY_SIZE(s->tim); i++) {
         object_initialize_child(obj, "tim[*]", &s->tim[i], TYPE_NPCM7XX_TIMER);
@@ -261,6 +263,10 @@ static void npcm7xx_realize(DeviceState *dev, Error **errp)
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->fuse_array), 0, NPCM7XX_OTP2_BA);
     npcm7xx_init_fuses(s);
 
+    /* Fake Memory Controller (MC). Cannot fail. */
+    sysbus_realize(SYS_BUS_DEVICE(&s->mc), &error_abort);
+    sysbus_mmio_map(SYS_BUS_DEVICE(&s->mc), 0, NPCM7XX_MC_BA);
+
     /* Timer Modules (TIM). Cannot fail. */
     QEMU_BUILD_BUG_ON(ARRAY_SIZE(npcm7xx_tim_addr) != ARRAY_SIZE(s->tim));
     for (i = 0; i < ARRAY_SIZE(s->tim); i++) {

hw/mem/meson.build

@@ -1,6 +1,7 @@
 mem_ss = ss.source_set()
 mem_ss.add(files('memory-device.c'))
 mem_ss.add(when: 'CONFIG_DIMM', if_true: files('pc-dimm.c'))
+mem_ss.add(when: 'CONFIG_NPCM7XX', if_true: files('npcm7xx_mc.c'))
 mem_ss.add(when: 'CONFIG_NVDIMM', if_true: files('nvdimm.c'))
 
 softmmu_ss.add_all(when: 'CONFIG_MEM_DEVICE', if_true: mem_ss)

hw/mem/npcm7xx_mc.c

@@ -0,0 +1,84 @@
+/*
+ * Nuvoton NPCM7xx Memory Controller stub
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+#include "qemu/osdep.h"
+
+#include "hw/mem/npcm7xx_mc.h"
+#include "qapi/error.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "qemu/units.h"
+
+#define NPCM7XX_MC_REGS_SIZE (4 * KiB)
+
+static uint64_t npcm7xx_mc_read(void *opaque, hwaddr addr, unsigned int size)
+{
+    /*
+     * If bits 8..11 @ offset 0 are not zero, the boot block thinks the memory
+     * controller has already been initialized and will skip DDR training.
+     */
+    if (addr == 0) {
+        return 0x100;
+    }
+
+    qemu_log_mask(LOG_UNIMP, "%s: mostly unimplemented\n", __func__);
+
+    return 0;
+}
+
+static void npcm7xx_mc_write(void *opaque, hwaddr addr, uint64_t v,
+                             unsigned int size)
+{
+    qemu_log_mask(LOG_UNIMP, "%s: mostly unimplemented\n", __func__);
+}
+
+static const MemoryRegionOps npcm7xx_mc_ops = {
+    .read = npcm7xx_mc_read,
+    .write = npcm7xx_mc_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+        .unaligned = false,
+    },
+};
+
+static void npcm7xx_mc_realize(DeviceState *dev, Error **errp)
+{
+    NPCM7xxMCState *s = NPCM7XX_MC(dev);
+
+    memory_region_init_io(&s->mmio, OBJECT(s), &npcm7xx_mc_ops, s, "regs",
+                          NPCM7XX_MC_REGS_SIZE);
+    sysbus_init_mmio(&s->parent, &s->mmio);
+}
+
+static void npcm7xx_mc_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->desc = "NPCM7xx Memory Controller stub";
+    dc->realize = npcm7xx_mc_realize;
+}
+
+static const TypeInfo npcm7xx_mc_types[] = {
+    {
+        .name = TYPE_NPCM7XX_MC,
+        .parent = TYPE_SYS_BUS_DEVICE,
+        .instance_size = sizeof(NPCM7xxMCState),
+        .class_init = npcm7xx_mc_class_init,
+    },
+};
+DEFINE_TYPES(npcm7xx_mc_types);

include/hw/arm/npcm7xx.h

@@ -18,6 +18,7 @@
 
 #include "hw/boards.h"
 #include "hw/cpu/a9mpcore.h"
+#include "hw/mem/npcm7xx_mc.h"
 #include "hw/misc/npcm7xx_clk.h"
 #include "hw/misc/npcm7xx_gcr.h"
 #include "hw/nvram/npcm7xx_otp.h"
@@ -71,6 +72,7 @@ typedef struct NPCM7xxState {
     NPCM7xxTimerCtrlState tim[3];
     NPCM7xxOTPState     key_storage;
     NPCM7xxOTPState     fuse_array;
+    NPCM7xxMCState      mc;
 } NPCM7xxState;
 
 #define TYPE_NPCM7XX    "npcm7xx"

include/hw/mem/npcm7xx_mc.h

@@ -0,0 +1,36 @@
+/*
+ * Nuvoton NPCM7xx Memory Controller stub
+ *
+ * Copyright 2020 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+#ifndef NPCM7XX_MC_H
+#define NPCM7XX_MC_H
+
+#include "exec/memory.h"
+#include "hw/sysbus.h"
+
+/**
+ * struct NPCM7xxMCState - Device state for the memory controller.
+ * @parent: System bus device.
+ * @mmio: Memory region through which registers are accessed.
+ */
+typedef struct NPCM7xxMCState {
+    SysBusDevice parent;
+
+    MemoryRegion mmio;
+} NPCM7xxMCState;
+
+#define TYPE_NPCM7XX_MC "npcm7xx-mc"
+#define NPCM7XX_MC(obj) OBJECT_CHECK(NPCM7xxMCState, (obj), TYPE_NPCM7XX_MC)
+
+#endif /* NPCM7XX_MC_H */