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>

2 files changed, 85 insertions, 0 deletions

diff --git a/hw/mem/meson.build b/hw/mem/meson.build
index ba424622bb..0d22f2b572 100644
--- a/hw/mem/meson.build
+++ b/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)
diff --git a/hw/mem/npcm7xx_mc.c b/hw/mem/npcm7xx_mc.c
new file mode 100644
index 0000000000..0435d06ab4
--- /dev/null
+++ b/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);