integrator: fix Linux boot failure by emulating dbg region

Commit 9b8c69243 (since reverted) broke the ability to boot the kernel
as the value returned by unassigned_mem_read returned non-zero and left
the kernel looping forever waiting for it to change (see
integrator_led_set in the kernel code).

Relying on a varying implementation detail is incorrect anyway so this
introduces a basic stub of a memory region for the debug/LED section
on the integrator board.

Signed-off-by: Alex Bennée <alex@bennee.com>
Message-id: 1382451366-9539-1-git-send-email-alex.bennee@linaro.org
[PMM: removed three unused fields from struct IntegratorDebugState]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 100 insertions, 0 deletions

diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index 2578e2939d..cca5c058cc 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -10,6 +10,7 @@ obj-$(CONFIG_VMPORT) += vmport.o
 
 # ARM devices
 common-obj-$(CONFIG_PL310) += arm_l2x0.o
+common-obj-$(CONFIG_INTEGRATOR_DEBUG) += arm_integrator_debug.o
 
 # PKUnity SoC devices
 common-obj-$(CONFIG_PUV3) += puv3_pm.o
diff --git a/hw/misc/arm_integrator_debug.c b/hw/misc/arm_integrator_debug.c
new file mode 100644
index 0000000000..99b720fbb9
--- /dev/null
+++ b/hw/misc/arm_integrator_debug.c
@@ -0,0 +1,99 @@
+/*
+ * LED, Switch and Debug control registers for ARM Integrator Boards
+ *
+ * This is currently a stub for this functionality but at least
+ * ensures something other than unassigned_mem_read() handles access
+ * to this area.
+ *
+ * The real h/w is described at:
+ *  http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0159b/Babbfijf.html
+ *
+ * Copyright (c) 2013 Alex Bennée <alex@bennee.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "hw/hw.h"
+#include "hw/sysbus.h"
+#include "exec/address-spaces.h"
+#include "hw/misc/arm_integrator_debug.h"
+
+#define INTEGRATOR_DEBUG(obj) \
+    OBJECT_CHECK(IntegratorDebugState, (obj), TYPE_INTEGRATOR_DEBUG)
+
+typedef struct {
+    SysBusDevice parent_obj;
+
+    MemoryRegion iomem;
+} IntegratorDebugState;
+
+static uint64_t intdbg_control_read(void *opaque, hwaddr offset,
+                                    unsigned size)
+{
+    switch (offset >> 2) {
+    case 0: /* ALPHA */
+    case 1: /* LEDS */
+    case 2: /* SWITCHES */
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: returning zero from %" HWADDR_PRIx ":%u\n",
+                      __func__, offset, size);
+        return 0;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset %" HWADDR_PRIx,
+                      __func__, offset);
+        return 0;
+    }
+}
+
+static void intdbg_control_write(void *opaque, hwaddr offset,
+                                 uint64_t value, unsigned size)
+{
+    switch (offset >> 2) {
+    case 1: /* ALPHA */
+    case 2: /* LEDS */
+    case 3: /* SWITCHES */
+        /* Nothing interesting implemented yet.  */
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: ignoring write of %" PRIu64
+                      " to %" HWADDR_PRIx ":%u\n",
+                      __func__, value, offset, size);
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: write of %" PRIu64
+                      " to bad offset %" HWADDR_PRIx "\n",
+                      __func__, value, offset);
+    }
+}
+
+static const MemoryRegionOps intdbg_control_ops = {
+    .read = intdbg_control_read,
+    .write = intdbg_control_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static void intdbg_control_init(Object *obj)
+{
+    SysBusDevice *sd = SYS_BUS_DEVICE(obj);
+    IntegratorDebugState *s = INTEGRATOR_DEBUG(obj);
+
+    memory_region_init_io(&s->iomem, NULL, &intdbg_control_ops,
+                          NULL, "dbg-leds", 0x1000000);
+    sysbus_init_mmio(sd, &s->iomem);
+}
+
+static const TypeInfo intdbg_info = {
+    .name          = TYPE_INTEGRATOR_DEBUG,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(IntegratorDebugState),
+    .instance_init = intdbg_control_init,
+};
+
+static void intdbg_register_types(void)
+{
+    type_register_static(&intdbg_info);
+}
+
+type_init(intdbg_register_types)