[Qemu-devel] [PATCH 1/9] PlatBus: Add Platform Bus

[Alexander Graf <agraf@suse.de>]

The platform bus is a very simple bus, similar to SysBus. However it has
a linear IRQ range that platform devices can attach to. It also provdes
mechanisms to dynamically place IO regions.

This patch implements the bus logic itself.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 hw/platbus/platbus.c         | 107 +++++++++++++++++++++++++++++++++++++++++++
 include/hw/platbus/platbus.h |  86 ++++++++++++++++++++++++++++++++++
 2 files changed, 193 insertions(+)
 create mode 100644 hw/platbus/platbus.c
 create mode 100644 include/hw/platbus/platbus.h

diff --git a/hw/platbus/platbus.c b/hw/platbus/platbus.c
new file mode 100644
index 0000000..769eb5d
--- /dev/null
+++ b/hw/platbus/platbus.c
@@ -0,0 +1,107 @@
+/*
+ * Generic platform bus with dynamic IRQ and IO placement
+ *
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ *
+ * Authors: Alexander Graf,   <agraf@suse.de>
+ *
+ * This 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.
+ *
+ * The platform bus is a very simple bus, similar to SysBus. However it has
+ * a linear IRQ range that platform devices can attach to. It also provdes
+ * mechanisms to dynamically place IO regions.
+ *
+ * Hence platform bus devices can be easily instantiated using -device from
+ * the command line.
+ */
+
+#include "qemu-common.h"
+#include "hw/platbus/platbus.h"
+
+int platbus_map_irq(PlatBusState *s, uint32_t *irqn, qemu_irq *irq)
+{
+    if (*irqn == (uint32_t)PLATBUS_DYNAMIC) {
+        /* Find the first available IRQ */
+        *irqn = find_first_zero_bit(s->used_irqs, PLATBUS_MAX_IRQ);
+    }
+
+    if ((*irqn >= PLATBUS_MAX_IRQ) || test_and_set_bit(*irqn, s->used_irqs)) {
+        hw_error("PlatBus: IRQ %d is already allocated or no free IRQ left",
+                 *irqn);
+    }
+
+    *irq = s->irqs[*irqn];
+
+    return 0;
+}
+
+void platbus_add_irq(PlatBusState *s, uint32_t irqn)
+{
+    clear_bit(irqn, s->used_irqs);
+}
+
+int platbus_map_region(PlatBusState *s, uint64_t *addr, MemoryRegion *mem)
+{
+    uint64_t size = memory_region_size(mem);
+    uint64_t size_pages = (size + ((1 << 12) - 1)) >> 12;
+    int page;
+    int i;
+
+    page = *addr >> 12;
+    if (*addr == (uint64_t)PLATBUS_DYNAMIC) {
+        uint64_t size_pages_align;
+
+        /* Align the region to at least its own size granularity */
+        if (is_power_of_2(size_pages)) {
+            size_pages_align = size_pages;
+        } else {
+            size_pages_align = pow2floor(size_pages) << 1;
+        }
+
+        /* Find the first available region that fits */
+        page = bitmap_find_next_zero_area(s->used_mem, PLATBUS_HOLE_PAGES, 0,
+                                          size_pages, size_pages_align);
+
+        *addr = (uint64_t)page << 12;
+    }
+
+    if (page >= PLATBUS_HOLE_PAGES || test_bit(page, s->used_mem) ||
+        (find_next_bit(s->used_mem, PLATBUS_HOLE_PAGES, page) < size_pages)) {
+        hw_error("PlatBus: Memory [%"PRIx64":%"PRIx64" is already allocated or "
+                 "no slot left", *addr, size);
+    }
+
+    for (i = page; i < (page + size_pages); i++) {
+        set_bit(i, s->used_mem);
+    }
+
+    memory_region_add_subregion(&s->mem, *addr, mem);
+
+    return 0;
+}
+
+static void platbus_init(Object *obj)
+{
+    PlatBusState *s = PLAT_BUS(obj);
+
+    QTAILQ_INIT(&s->devices);
+    bitmap_fill(s->used_irqs, PLATBUS_MAX_IRQ);
+    memory_region_init(&s->mem, NULL, "platbus", PLATBUS_HOLE);
+}
+
+static const TypeInfo platbus_type_info = {
+    .name = TYPE_PLAT_BUS,
+    .parent = TYPE_BUS,
+    .instance_size = sizeof(PlatBusState),
+    .instance_init = platbus_init,
+};
+
+static void platbus_register_types(void)
+{
+    type_register_static(&platbus_type_info);
+}
+
+type_init(platbus_register_types)
diff --git a/include/hw/platbus/platbus.h b/include/hw/platbus/platbus.h
new file mode 100644
index 0000000..d260fb8
--- /dev/null
+++ b/include/hw/platbus/platbus.h
@@ -0,0 +1,86 @@
+/*
+ * Generic platform bus with dynamic IRQ and IO placement
+ *
+ * Copyright 2013 Freescale Semiconductor, Inc.
+ *
+ * Authors: Alexander Graf,   <agraf@suse.de>
+ *
+ * This 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.
+ */
+
+#ifndef QEMU_HW_PLATBUS_PLATBUS_H
+#define QEMU_HW_PLATBUS_PLATBUS_H
+
+#include "qemu-common.h"
+#include "hw/qdev.h"
+#include "qemu/bitmap.h"
+/* for QDEV_MAX_IRQ */
+#include "hw/sysbus.h"
+
+#define PLATBUS_MAX_IRQ QDEV_MAX_IRQ
+#define PLATBUS_DYNAMIC -1LL
+#define PLATBUS_HOLE (128ULL * 1024 * 1024) /* 128 MB */
+#define PLATBUS_HOLE_PAGES (PLATBUS_HOLE >> 12)
+
+#define TYPE_PLAT_BUS "platbus"
+#define PLAT_BUS(obj) OBJECT_CHECK(PlatBusState, (obj), TYPE_PLAT_BUS)
+
+typedef struct PlatBusState {
+    /*< private >*/
+    BusState parent_obj;
+    qemu_irq irqs[PLATBUS_MAX_IRQ];
+    DECLARE_BITMAP(used_irqs, PLATBUS_MAX_IRQ);
+    DECLARE_BITMAP(used_mem, PLATBUS_HOLE_PAGES);
+    /*< public >*/
+
+    QTAILQ_HEAD(, PlatBusDeviceState) devices;
+    MemoryRegion mem;
+} PlatBusState;
+
+/**
+ * platbus_map_region:
+ * @s: Bus to map the region to
+ * @addr: Pointer to the offset inside the platform bus address range we want to
+ *        map to. Should be PLATBUS_DYNAMIC if the bus is supposed to give us an
+ *        address. Gets written back with the actually mapped address.
+ * @mem: Pointer to a properly initialized MemoryRegion which should get mapped
+ *       into the platform bus's address space. Does not get modified.
+ *
+ * Tell the platform bus to map a device's memory region into the platform bus's
+ * address range.
+ *
+ * Returns: 0 on success. Negative values on error.
+ */
+int platbus_map_region(PlatBusState *s, uint64_t *addr, MemoryRegion *mem);
+
+/**
+ * platbus_map_region:
+ * @s: Bus to map the IRQ to
+ * @irqn: Pointer to the IRQ inside the platform bus IRQ range we want to
+ *        map to. Should be PLATBUS_DYNAMIC if the bus is supposed to give us an
+ *        IRQ number. Gets written back with the actually mapped IRQ.
+ * @irq: Pointer to a qemu_irq field. Gets populated with a real qemu_irq when
+ *       the mapping gets successfully established.
+ *
+ * Tell the platform bus to map a device's IRQ into the platform bus's IRQ range.
+ *
+ * Returns: 0 on success. Negative values on error.
+ */
+int platbus_map_irq(PlatBusState *s, uint32_t *irqn, qemu_irq *irq);
+
+/**
+ * platbus_add_irq:
+ * @s: Bus to map the IRQ to
+ * @irqn: IRQ number that gets declared valid
+ *
+ * Tell the platform bus that one of its internal IRQ lines was successfully
+ * populated with a usable qemu_irq object.
+ *
+ * Returns: 0 on success. Negative values on error.
+ */
+void platbus_add_irq(PlatBusState *s, uint32_t irqn);
+
+#endif /* !QEMU_HW_PLATBUS_PLATBUS_H */
-- 
1.8.1.4