net/can: simple messages transport implementation for QEMU

The CanBusState state structure is created for each
emulated CAN channel. Individual clients/emulated
CAN interfaces or host interface connection registers
to the bus by CanBusClientState structure.

The CAN core is prepared to support connection to the
real host CAN bus network. The commit with such support
for Linux SocketCAN follows.

Implementation is as simple as possible.  There is no state to be
migrated, and messages prioritization and queuing are not considered
for now.  But it is intended to be extended when need arises.

Development repository and more documentation at

https://gitlab.fel.cvut.cz/canbus/qemu-canbus

The work is based on Jin Yang GSoC 2013 work funded
by Google and mentored in frame of RTEMS project GSoC
slot donated to QEMU.

Rewritten for QEMU-2.0+ versions and architecture cleanup
by Pavel Pisa (Czech Technical University in Prague).

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 251 insertions, 0 deletions

diff --git a/net/can/Makefile.objs b/net/can/Makefile.objs
new file mode 100644
index 0000000..ef97fdb
--- /dev/null
+++ b/net/can/Makefile.objs
@@ -0,0 +1 @@
+common-obj-y += can_core.o can_host.o
diff --git a/net/can/can_core.c b/net/can/can_core.c
new file mode 100644
index 0000000..2a83cad
--- /dev/null
+++ b/net/can/can_core.c
@@ -0,0 +1,138 @@
+/*
+ * CAN common CAN bus emulation support
+ *
+ * Copyright (c) 2013-2014 Jin Yang
+ * Copyright (c) 2014-2018 Pavel Pisa
+ *
+ * Initial development supported by Google GSoC 2013 from RTEMS project slot
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "qemu/osdep.h"
+#include "chardev/char.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "net/can_emu.h"
+#include "qom/object_interfaces.h"
+
+struct CanBusState {
+    Object object;
+
+    QTAILQ_HEAD(, CanBusClientState) clients;
+};
+
+static void can_bus_instance_init(Object *object)
+{
+    CanBusState *bus = (CanBusState *)object;
+
+    QTAILQ_INIT(&bus->clients);
+}
+
+int can_bus_insert_client(CanBusState *bus, CanBusClientState *client)
+{
+    client->bus = bus;
+    QTAILQ_INSERT_TAIL(&bus->clients, client, next);
+    return 0;
+}
+
+int can_bus_remove_client(CanBusClientState *client)
+{
+    CanBusState *bus = client->bus;
+    if (bus == NULL) {
+        return 0;
+    }
+
+    QTAILQ_REMOVE(&bus->clients, client, next);
+    client->bus = NULL;
+    return 1;
+}
+
+ssize_t can_bus_client_send(CanBusClientState *client,
+             const struct qemu_can_frame *frames, size_t frames_cnt)
+{
+    int ret = 0;
+    CanBusState *bus = client->bus;
+    CanBusClientState *peer;
+    if (bus == NULL) {
+        return -1;
+    }
+
+    QTAILQ_FOREACH(peer, &bus->clients, next) {
+        if (peer->info->can_receive(peer)) {
+            if (peer == client) {
+                /* No loopback support for now */
+                continue;
+            }
+            if (peer->info->receive(peer, frames, frames_cnt) > 0) {
+                ret = 1;
+            }
+        }
+    }
+
+    return ret;
+}
+
+int can_bus_filter_match(struct qemu_can_filter *filter, qemu_canid_t can_id)
+{
+    int m;
+    if (((can_id | filter->can_mask) & QEMU_CAN_ERR_FLAG)) {
+        return (filter->can_mask & QEMU_CAN_ERR_FLAG) != 0;
+    }
+    m = (can_id & filter->can_mask) == (filter->can_id & filter->can_mask);
+    return filter->can_id & QEMU_CAN_INV_FILTER ? !m : m;
+}
+
+int can_bus_client_set_filters(CanBusClientState *client,
+             const struct qemu_can_filter *filters, size_t filters_cnt)
+{
+    return 0;
+}
+
+
+static bool can_bus_can_be_deleted(UserCreatable *uc)
+{
+    return false;
+}
+
+static void can_bus_class_init(ObjectClass *klass,
+                                void *class_data G_GNUC_UNUSED)
+{
+    UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);
+
+    uc_klass->can_be_deleted = can_bus_can_be_deleted;
+}
+
+static const TypeInfo can_bus_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_CAN_BUS,
+    .instance_size = sizeof(CanBusState),
+    .instance_init = can_bus_instance_init,
+    .class_init = can_bus_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+static void can_bus_register_types(void)
+{
+    type_register_static(&can_bus_info);
+}
+
+type_init(can_bus_register_types);
diff --git a/net/can/can_host.c b/net/can/can_host.c
new file mode 100644
index 0000000..c3d2652
--- /dev/null
+++ b/net/can/can_host.c
@@ -0,0 +1,112 @@
+/*
+ * CAN generic CAN host connection support
+ *
+ * Copyright (c) 2013-2014 Jin Yang
+ * Copyright (c) 2014-2018 Pavel Pisa
+ *
+ * Initial development supported by Google GSoC 2013 from RTEMS project slot
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "qemu/osdep.h"
+#include "chardev/char.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "qom/object_interfaces.h"
+#include "net/can_emu.h"
+#include "net/can_host.h"
+
+struct CanBusState {
+    Object object;
+
+    QTAILQ_HEAD(, CanBusClientState) clients;
+};
+
+static void can_host_disconnect(CanHostState *ch)
+{
+    CanHostClass *chc = CAN_HOST_GET_CLASS(ch);
+
+    can_bus_remove_client(&ch->bus_client);
+    chc->disconnect(ch);
+}
+
+static void can_host_connect(CanHostState *ch, Error **errp)
+{
+    CanHostClass *chc = CAN_HOST_GET_CLASS(ch);
+    Error *local_err = NULL;
+
+    chc->connect(ch, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    can_bus_insert_client(ch->bus, &ch->bus_client);
+}
+
+static void can_host_unparent(Object *obj)
+{
+    can_host_disconnect(CAN_HOST(obj));
+}
+
+static void can_host_complete(UserCreatable *uc, Error **errp)
+{
+    can_host_connect(CAN_HOST(uc), errp);
+}
+
+static void can_host_instance_init(Object *obj)
+{
+    CanHostState *ch = CAN_HOST(obj);
+
+    object_property_add_link(obj, "canbus", TYPE_CAN_BUS,
+                             (Object **)&ch->bus,
+                             object_property_allow_set_link,
+                             OBJ_PROP_LINK_UNREF_ON_RELEASE,
+                             &error_abort);
+}
+
+static void can_host_class_init(ObjectClass *klass,
+                                void *class_data G_GNUC_UNUSED)
+{
+    UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);
+
+    klass->unparent = can_host_unparent;
+    uc_klass->complete = can_host_complete;
+}
+
+static const TypeInfo can_host_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_CAN_HOST,
+    .instance_size = sizeof(CanHostState),
+    .class_size = sizeof(CanHostClass),
+    .abstract = true,
+    .instance_init = can_host_instance_init,
+    .class_init = can_host_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+static void can_host_register_types(void)
+{
+    type_register_static(&can_host_info);
+}
+
+type_init(can_host_register_types);