[Qemu-devel] [RFC] New device API

[Paul Brook]

The attached patch is my attempt at a new internal API for device creation in 
qemu.

The long term goal here is fully dynamic machine construction, i.e. a user 
supplied configuration file/tree rather than the current hardcoded board 
configs.

As a first step towards this, I've implemented an API that allows devices to 
be created and configured without requiring device specific knowledge.

There are two sides to this API.  The device side allows a device to 
register/configure functionality (e.g. MMIO regions, IRQs, character devices, 
etc). Most of the infrastructure for this is already present, we just need to 
configure it consistently, rather than on an ad-hoc basis. I expect this API 
to remain largely unchanged[1].

The board side allows creation on configuration of devices. In the medium term 
I expect this to go away, and be replaced by data driven configuration.

I also expect that this device abstraction will let itself to a system bus 
model to solve many of the IOMMU/DMA/address mapping issues that qemu 
currently can't handle.

There are still a few rough edges. Busses aren't handled in a particularly 
consistent way, PCI isn't particularly well integrated, and the 
implementation of things like qdev_get_chardev is an ugly hack mapping onto 
current commandline options. However I believe the device side API is fairly 
solid, and is a necessary prerequisite for fixing the bigger configuration 
problem.

I've converted a bunch of devices, anyone interested in seeing how it fits 
together in practice can pull from
  git://repo.or.cz/qemu/pbrook.git qdev

It you have objections to or suggestion about this approach please speak up 
now, but please bear in ming that this code is still somewhat in flux and the 
caveats mentioned above.

Paul

[1] I subscribe to the linux kernel theory that stable internal APIs are a 
coincidence, not a feature. i.e. a consistent internal API is good, but that 
it should be changed whenever technically desirable. I have no interest in 
maintaining a fixed API for the benefit of third parties.

commit 11c765848af6cb345a81f2722f141b305538182d
Author: Paul Brook <address@hidden>
Date:   Mon May 4 17:13:08 2009 +0100

    Basic qdev infrastructure.
    
    Signed-off-by: Paul Brook <address@hidden>

diff --git a/Makefile.target b/Makefile.target
index f735105..a35e724 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -498,6 +498,7 @@ endif #CONFIG_BSD_USER
 # System emulator target
 ifndef CONFIG_USER_ONLY
 
+DEVICES=
 OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o dma-helpers.o
 # virtio has to be here due to weird dependency between PCI and virtio-net.
 # need to fix this properly
@@ -686,6 +687,13 @@ ifeq ($(TARGET_BASE_ARCH), m68k)
 OBJS+= an5206.o mcf5206.o mcf_uart.o mcf_intc.o mcf5208.o mcf_fec.o
 OBJS+= m68k-semi.o dummy_m68k.o
 endif
+
+DEVICE_OBJS=$(addsuffix .o,$(DEVICES))
+$(DEVICE_OBJS): CPPFLAGS+=-DDEVICE_NAME=$(subst -,_,$(@:.o=))
+
+OBJS+=$(DEVICE_OBJS)
+OBJS+=devices.o qdev.o
+
 ifdef CONFIG_GDBSTUB
 OBJS+=gdbstub.o gdbstub-xml.o
 endif
@@ -752,6 +760,9 @@ endif
 qemu-options.h: $(SRC_PATH)/qemu-options.hx
        $(call quiet-command,sh $(SRC_PATH)/hxtool -h < $< > $@,"  GEN   
$(TARGET_DIR)$@")
 
+devices.c: gen_devices.sh Makefile.target config.mak
+       $(call quiet-command,$(SHELL) $(SRC_PATH)/gen_devices.sh $@ $(subst 
-,_,$(DEVICES)),"  GEN   $(TARGET_DIR)$@")
+
 clean:
        rm -f *.o *.a *~ $(PROGS) nwfpe/*.o fpu/*.o qemu-options.h gdbstub-xml.c
        rm -f *.d */*.d tcg/*.o
diff --git a/gen_devices.sh b/gen_devices.sh
new file mode 100644
index 0000000..1d6ec12
--- /dev/null
+++ b/gen_devices.sh
@@ -0,0 +1,17 @@
+#! /bin/sh
+# Call device init functions.
+
+file="$1"
+shift
+devices="$@"
+echo '/* Generated by gen_devices.sh */' > $file
+echo '#include "sysemu.h"' >> $file
+for x in $devices ; do
+    echo "void ${x}_register(void);" >> $file
+done
+echo "void register_devices(void)" >> $file
+echo "{" >> $file
+for x in $devices ; do
+    echo "    ${x}_register();" >> $file
+done
+echo "}" >> $file
diff --git a/hw/qdev.c b/hw/qdev.c
new file mode 100644
index 0000000..eb8c172
--- /dev/null
+++ b/hw/qdev.c
@@ -0,0 +1,294 @@
+/*
+ *  Dynamic device configuration and creation.
+ *
+ *  Copyright (c) 2009 CodeSourcery
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "hw.h"
+#include "qdev.h"
+#include "sysemu.h"
+
+#include <assert.h>
+
+struct DeviceProperty
+{
+    const char *name;
+    union {
+        int i;
+        void *ptr;
+    } value;
+    DeviceProperty *next;
+};
+
+struct DeviceType
+{
+    const char *name;
+    qdev_initfn init;
+    void *opaque;
+    int size;
+    DeviceType *next;
+};
+
+static DeviceType *device_type_list;
+
+/* Register a new device type.  */
+DeviceType *qdev_register(const char *name, int size, qdev_initfn init,
+                          void *opaque)
+{
+    DeviceType *t;
+
+    assert(size >= sizeof(DeviceState));
+
+    t = qemu_mallocz(sizeof(DeviceType));
+    t->next = device_type_list;
+    device_type_list = t;
+    t->name = qemu_strdup(name);
+    t->size = size;
+    t->init = init;
+    t->opaque = opaque;
+
+    return t;
+}
+
+/* Create a new device.  This only initializes the device state structure
+   and allows properties to be set.  qdev_init should be called to
+   initialize the actual device emulation.  */
+DeviceState *qdev_create(const char *name)
+{
+    DeviceType *t;
+    DeviceState *dev;
+
+    for (t = device_type_list; t; t = t->next) {
+        if (strcmp(t->name, name) == 0) {
+            break;
+        }
+    }
+    if (!t) {
+        fprintf(stderr, "Unknown device '%s'\n", name);
+        exit(1);
+    }
+
+    dev = qemu_mallocz(t->size);
+    dev->name = name;
+    dev->type = t;
+    return dev;
+}
+
+/* Initialize a device.  Device properties should be set before calling
+   this function.  IRQs and MMIO regions should be connected/mapped after
+   calling this function.  */
+void qdev_init(DeviceState *dev)
+{
+    dev->type->init(dev, dev->type->opaque);
+}
+
+void qdev_connect_irq(DeviceState *dev, int n, qemu_irq irq)
+{
+    assert(n >= 0 && n < dev->num_irq);
+    dev->irqs[n] = 0;
+    if (dev->irqp[n]) {
+        *dev->irqp[n] = irq;
+    }
+}
+
+void qdev_mmio_map(DeviceState *dev, int n, target_phys_addr_t addr)
+{
+    assert(n >= 0 && n < dev->num_mmio);
+
+    if (dev->mmio[n].addr == addr) {
+        /* ??? region already mapped here.  */
+        return;
+    }
+    if (dev->mmio[n].addr != (target_phys_addr_t)-1) {
+        /* Unregister previous mapping.  */
+        cpu_register_physical_memory(dev->mmio[n].addr, dev->mmio[n].size,
+                                     IO_MEM_UNASSIGNED);
+    }
+    dev->mmio[n].addr = addr;
+    if (dev->mmio[n].cb) {
+        dev->mmio[n].cb(dev, addr);
+    } else {
+        cpu_register_physical_memory(addr, dev->mmio[n].size,
+                                     dev->mmio[n].iofunc);
+    }
+}
+
+void qdev_set_bus(DeviceState *dev, void *bus)
+{
+    assert(!dev->bus);
+    dev->bus = bus;
+}
+
+static DeviceProperty *create_prop(DeviceState *dev, const char *name)
+{
+    DeviceProperty *prop;
+
+    /* TODO: Check for duplicate properties.  */
+    prop = qemu_mallocz(sizeof(*prop));
+    prop->name = qemu_strdup(name);
+    prop->next = dev->props;
+    dev->props = prop;
+
+    return prop;
+}
+
+void qdev_set_prop_int(DeviceState *dev, const char *name, int value)
+{
+    DeviceProperty *prop;
+
+    prop = create_prop(dev, name);
+    prop->value.i = value;
+}
+
+void qdev_set_prop_ptr(DeviceState *dev, const char *name, void *value)
+{
+    DeviceProperty *prop;
+
+    prop = create_prop(dev, name);
+    prop->value.ptr = value;
+}
+
+
+qemu_irq qdev_get_irq_sink(DeviceState *dev, int n)
+{
+    assert(n >= 0 && n < dev->num_irq_sink);
+    return dev->irq_sink[n];
+}
+
+void qdev_init_mmio(DeviceState *dev, target_phys_addr_t size, int iofunc)
+{
+    int n;
+
+    assert(dev->num_mmio < QDEV_MAX_MMIO);
+    n = dev->num_mmio++;
+    dev->mmio[n].addr = -1;
+    dev->mmio[n].size = size;
+    dev->mmio[n].iofunc = iofunc;
+}
+
+void qdev_init_mmio_cb(DeviceState *dev, target_phys_addr_t size,
+                       mmio_mapfunc cb)
+{
+    int n;
+
+    assert(dev->num_mmio < QDEV_MAX_MMIO);
+    n = dev->num_mmio++;
+    dev->mmio[n].addr = -1;
+    dev->mmio[n].size = size;
+    dev->mmio[n].cb = cb;
+}
+
+/* Request an IRQ source.  The actual IRQ object may be populated later.  */
+void qdev_init_irq(DeviceState *dev, qemu_irq *p)
+{
+    int n;
+
+    assert(dev->num_irq < QDEV_MAX_IRQ);
+    n = dev->num_irq++;
+    dev->irqp[n] = p;
+}
+
+/* Pass IRQs from a target device.  */
+void qdev_pass_irq(DeviceState *dev, DeviceState *target)
+{
+    int i;
+    assert(dev->num_irq == 0);
+    dev->num_irq = target->num_irq;
+    for (i = 0; i < dev->num_irq; i++) {
+        dev->irqp[i] = target->irqp[i];
+    }
+}
+
+/* Register device IRQ sinks.  */
+void qdev_init_irq_sink(DeviceState *dev, qemu_irq_handler handler, int nirq)
+{
+    dev->num_irq_sink = nirq;
+    dev->irq_sink = qemu_allocate_irqs(handler, dev, nirq);
+}
+
+/* Get a character (serial) device interface.  */
+CharDriverState *qdev_init_chardev(DeviceState *dev)
+{
+    static int next_serial;
+    static int next_virtconsole;
+    if (strncmp(dev->name, "virtio", 6) == 0) {
+        return virtcon_hds[next_virtconsole++];
+    } else {
+        return serial_hds[next_serial++];
+    }
+}
+
+void *qdev_get_bus(DeviceState *dev)
+{
+    return dev->bus;
+}
+
+static DeviceProperty *find_prop(DeviceState *dev, const char *name)
+{
+    DeviceProperty *prop;
+
+    for (prop = dev->props; prop; prop = prop->next) {
+        if (strcmp(prop->name, name) == 0) {
+            return prop;
+        }
+    }
+    /* TODO: When this comes from a config file we will need to handle
+       missing properties gracefully.  */
+    abort();
+}
+
+int qdev_get_prop_int(DeviceState *dev, const char *name)
+{
+    DeviceProperty *prop;
+
+    prop = find_prop(dev, name);
+    return prop->value.i;
+}
+
+void *qdev_get_prop_ptr(DeviceState *dev, const char *name)
+{
+    DeviceProperty *prop;
+
+    prop = find_prop(dev, name);
+    return prop->value.ptr;
+}
+
+DeviceState *qdev_create_varargs(const char *name,
+                                 target_phys_addr_t addr, ...)
+{
+    DeviceState *dev;
+    va_list va;
+    qemu_irq irq;
+    int n;
+
+    dev = qdev_create(name);
+    qdev_init(dev);
+    if (addr != (target_phys_addr_t)-1) {
+        qdev_mmio_map(dev, 0, addr);
+    }
+    va_start(va, addr);
+    n = 0;
+    while (1) {
+        irq = va_arg(va, qemu_irq);
+        if (!irq) {
+            break;
+        }
+        qdev_connect_irq(dev, n, irq);
+        n++;
+    }
+    return dev;
+}
diff --git a/hw/qdev.h b/hw/qdev.h
new file mode 100644
index 0000000..08b2713
--- /dev/null
+++ b/hw/qdev.h
@@ -0,0 +1,89 @@
+#ifndef QDEV_H
+#define QDEV_H
+
+#include "irq.h"
+
+typedef struct DeviceType DeviceType;
+
+#define QDEV_MAX_MMIO 5
+#define QDEV_MAX_IRQ 32
+
+typedef struct DeviceProperty DeviceProperty;
+
+typedef void (*mmio_mapfunc)(DeviceState *dev, target_phys_addr_t addr);
+
+/* This structure should not be accessed directly.  We declare it here
+   so that it can be embedded in individual device state structures.  */
+struct DeviceState
+{
+    const char *name;
+    DeviceType *type;
+    void *bus;
+    int num_irq;
+    qemu_irq irqs[QDEV_MAX_IRQ];
+    qemu_irq *irqp[QDEV_MAX_IRQ];
+    int num_irq_sink;
+    qemu_irq *irq_sink;
+    int num_mmio;
+    struct {
+        target_phys_addr_t addr;
+        target_phys_addr_t size;
+        mmio_mapfunc cb;
+        int iofunc;
+    } mmio[QDEV_MAX_MMIO];
+    DeviceProperty *props;
+};
+
+
+/*** Board API.  This should go away once we have a machine config file.  ***/
+
+DeviceState *qdev_create(const char *name);
+void qdev_init(DeviceState *dev);
+
+/* Set properties between creation and init.  */
+void qdev_set_bus(DeviceState *dev, void *bus);
+void qdev_set_prop_int(DeviceState *dev, const char *name, int value);
+void qdev_set_prop_ptr(DeviceState *dev, const char *name, void *value);
+
+/* Configure device after init.   */
+void qdev_connect_irq(DeviceState *dev, int n, qemu_irq irq);
+void qdev_mmio_map(DeviceState *dev, int n, target_phys_addr_t addr);
+qemu_irq qdev_get_irq_sink(DeviceState *dev, int n);
+
+
+/*** Device API.  ***/
+
+typedef void (*qdev_initfn)(DeviceState *dev, void *opaque);
+
+DeviceType *qdev_register(const char *name, int size, qdev_initfn init,
+                          void *opaque);
+
+/* Register device properties.  */
+void qdev_init_mmio(DeviceState *dev, target_phys_addr_t size, int iofunc);
+void qdev_init_mmio_cb(DeviceState *dev, target_phys_addr_t size,
+                       mmio_mapfunc cb);
+void qdev_init_irq(DeviceState *dev, qemu_irq *p);
+void qdev_pass_irq(DeviceState *dev, DeviceState *target);
+void qdev_init_irq_sink(DeviceState *dev, qemu_irq_handler handler, int nirq);
+
+CharDriverState *qdev_init_chardev(DeviceState *dev);
+
+void *qdev_get_bus(DeviceState *dev);
+int qdev_get_prop_int(DeviceState *dev, const char *name);
+void *qdev_get_prop_ptr(DeviceState *dev, const char *name);
+
+/* Helper function for creating devices with no special properties.  */
+DeviceState *qdev_create_varargs(const char *name,
+                                 target_phys_addr_t addr, ...);
+static inline DeviceState *qdev_create_simple(const char *name,
+                                              target_phys_addr_t addr,
+                                              qemu_irq irq)
+{
+    return qdev_create_varargs(name, addr, irq, NULL);
+}
+
+#ifdef DEVICE_NAME
+void glue(DEVICE_NAME, _register)(void);
+#endif
+
+#endif
diff --git a/qemu-common.h b/qemu-common.h
index c90c3e3..e792e94 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -178,6 +178,7 @@ typedef struct PCIDevice PCIDevice;
 typedef struct SerialState SerialState;
 typedef struct IRQState *qemu_irq;
 struct pcmcia_card_s;
+typedef struct DeviceState DeviceState;
 
 /* CPU save/load.  */
 void cpu_save(QEMUFile *f, void *opaque);
diff --git a/sysemu.h b/sysemu.h
index 9bb9fbc..24c9fe6 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -259,4 +259,6 @@ int get_param_value(char *buf, int buf_size,
                     const char *tag, const char *str);
 int check_params(const char * const *params, const char *str);
 
+void register_devices(void);
+
 #endif
diff --git a/vl.c b/vl.c
index 867111c..b21ea19 100644
--- a/vl.c
+++ b/vl.c
@@ -5904,6 +5904,8 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    register_devices();
+
     machine->init(ram_size, vga_ram_size, boot_devices,
                   kernel_filename, kernel_cmdline, initrd_filename, cpu_model);
 

commit 82ec0ee7bed3280952cab897810c2fe00b0abff2
Author: Paul Brook <address@hidden>
Date:   Mon May 4 17:13:11 2009 +0100

    qdev scsi bus infrastructure
    
    Signed-off-by: Paul Brook <address@hidden>

diff --git a/hw/qdev.c b/hw/qdev.c
index 868ba75..7874049 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -309,3 +309,21 @@ BlockDriverState *qdev_init_bdrv(DeviceState *dev, 
BlockInterfaceType type)
     }
     return drives_table[index].bdrv;
 }
+
+static int next_scsi_bus;
+
+/* Create a scsi bus, and attach devices to it.  */
+void qdev_init_scsi(DeviceState *dev, SCSIAttachFn attach)
+{
+   int bus = next_scsi_bus++;
+   int unit;
+   int index;
+
+   for (unit = 0; unit < MAX_SCSI_DEVS; unit++) {
+       index = drive_get_index(IF_SCSI, bus, unit);
+       if (index == -1) {
+           continue;
+       }
+       attach(dev, drives_table[index].bdrv, unit);
+   }
+}
diff --git a/hw/qdev.h b/hw/qdev.h
index 08b2713..79eb22f 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -54,6 +54,7 @@ qemu_irq qdev_get_irq_sink(DeviceState *dev, int n);
 /*** Device API.  ***/
 
 typedef void (*qdev_initfn)(DeviceState *dev, void *opaque);
+typedef void (*SCSIAttachFn)(void *opaque, BlockDriverState *bdrv, int unit);
 
 DeviceType *qdev_register(const char *name, int size, qdev_initfn init,
                           void *opaque);
@@ -65,6 +66,7 @@ void qdev_init_mmio_cb(DeviceState *dev, target_phys_addr_t 
size,
 void qdev_init_irq(DeviceState *dev, qemu_irq *p);
 void qdev_pass_irq(DeviceState *dev, DeviceState *target);
 void qdev_init_irq_sink(DeviceState *dev, qemu_irq_handler handler, int nirq);
+void qdev_init_scsi(DeviceState *dev, SCSIAttachFn attach);
 
 CharDriverState *qdev_init_chardev(DeviceState *dev);