SSP bus framework

Signed-off-by: Paul Brook <paul@codesourcery.com>

2 files changed, 93 insertions, 0 deletions

diff --git a/hw/ssi.c b/hw/ssi.c
new file mode 100644
index 0000000..9dfdbe9
--- /dev/null
+++ b/hw/ssi.c
@@ -0,0 +1,52 @@
+/*
+ * QEMU Synchronous Serial Interface support
+ *
+ * Copyright (c) 2009 CodeSourcery.
+ * Written by Paul Brook
+ *
+ * This code is licenced under the GNU GPL v2.
+ */
+
+#include "ssi.h"
+
+struct SSIBus {
+    SSISlave *slave;
+};
+
+static void ssi_slave_init(DeviceState *dev, void *opaque)
+{
+    SSISlaveInfo *info = opaque;
+    SSISlave *s = SSI_SLAVE_FROM_QDEV(dev);
+    SSIBus *bus = qdev_get_bus(dev);
+
+    bus->slave = s;
+    s->info = info;
+    info->init(s);
+}
+
+void ssi_register_slave(const char *name, int size, SSISlaveInfo *info)
+{
+    assert(size >= sizeof(SSISlave));
+    qdev_register(name, size, ssi_slave_init, info);
+}
+
+DeviceState *ssi_create_slave(SSIBus *bus, const char *name)
+{
+    DeviceState *dev;
+    dev = qdev_create(bus, name);
+    qdev_init(dev);
+    return dev;
+}
+
+SSIBus *ssi_create_bus(void)
+{
+    return qemu_mallocz(sizeof(SSIBus));
+}
+
+uint32_t ssi_transfer(SSIBus *bus, uint32_t val)
+{
+    if (!bus->slave) {
+        return 0;
+    }
+    return bus->slave->info->transfer(bus->slave, val);
+}
diff --git a/hw/ssi.h b/hw/ssi.h
new file mode 100644
index 0000000..d9865e6
--- /dev/null
+++ b/hw/ssi.h
@@ -0,0 +1,41 @@
+/* QEMU Synchronous Serial Interface support.  */
+
+/* In principle SSI is a point-point interface.  As such the qemu
+   implementation has a single slave device on a "bus".
+   However it is fairly common for boards to have multiple slaves
+   connected to a single master, and select devices with an external
+   chip select.  This is implemented in qemu by having an explicit mux device.
+   It is assumed that master and slave are both using the same transfer width.
+   */
+
+#ifndef QEMU_SSI_H
+#define QEMU_SSI_H
+
+#include "qdev.h"
+
+typedef struct SSISlave SSISlave;
+
+/* Slave devices.  */
+typedef struct {
+    void (*init)(SSISlave *dev);
+    uint32_t (*transfer)(SSISlave *dev, uint32_t val);
+} SSISlaveInfo;
+
+struct SSISlave {
+    DeviceState qdev;
+    SSISlaveInfo *info;
+};
+
+#define SSI_SLAVE_FROM_QDEV(dev) DO_UPCAST(SSISlave, qdev, dev)
+#define FROM_SSI_SLAVE(type, dev) DO_UPCAST(type, ssidev, dev)
+
+void ssi_register_slave(const char *name, int size, SSISlaveInfo *info);
+
+DeviceState *ssi_create_slave(SSIBus *bus, const char *name);
+
+/* Master interface.  */
+SSIBus *ssi_create_bus(void);
+
+uint32_t ssi_transfer(SSIBus *bus, uint32_t val);
+
+#endif