[Qemu-devel] [PATCH v3 03/17] qdev: Allow device addressing via 'driver.instance'

[Jan Kiszka]

From: Jan Kiszka <address@hidden>

Extend qbus_find_dev to allow addressing of devices without an unique id
via an optional per-bus instance number. The new formats are
'driver.instance' and 'alias.instance'.

Signed-off-by: Jan Kiszka <address@hidden>
---
 docs/qdev-device-use.txt |   14 +++++++++++++-
 hw/qdev.c                |   23 ++++++++++++++++++-----
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/docs/qdev-device-use.txt b/docs/qdev-device-use.txt
index 9ac1fa1..74d4960 100644
--- a/docs/qdev-device-use.txt
+++ b/docs/qdev-device-use.txt
@@ -1,6 +1,6 @@
 = How to convert to -device & friends =
 
-=== Specifying Bus and Address on Bus ===
+=== Specifying Bus, Address on Bus, and Devices ===
 
 In qdev, each device has a parent bus.  Some devices provide one or
 more buses for children.  You can specify a device's parent bus with
@@ -24,6 +24,18 @@ Furthermore, if a device only hosts a single bus, the bus 
name can be
 omitted in the path.  Example: /i440FX-pcihost/PIIX3 abbreviates
 /i440FX-pcihost/pci.0/PIIX3/isa.0 as none of the buses has siblings.
 
+Existing devices can be addressed either via a unique ID if it was
+assigned during creation or via the device tree path:
+
+/full_bus_address/driver_name[.instance_number]
+    or
+abbreviated_bus_address/driver_name[.instance_number]
+
+The instance number is zero-based.
+
+Example: /i440FX-pcihost/pci.0/e1000.1 addresses the second e1000
+adapter on the bus 'pci.0'.
+
 Note: the USB device address can't be controlled at this time.
 
 === Block Devices ===
diff --git a/hw/qdev.c b/hw/qdev.c
index 2e50531..6b4a629 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -527,28 +527,41 @@ static BusState *qbus_find_bus(DeviceState *dev, char 
*elem)
     return NULL;
 }
 
-static DeviceState *qbus_find_dev(BusState *bus, char *elem)
+static DeviceState *qbus_find_dev(BusState *bus, const char *elem)
 {
     DeviceState *dev;
+    int instance, n;
+    char buf[128];
 
     /*
      * try to match in order:
      *   (1) instance id, if present
-     *   (2) driver name
-     *   (3) driver alias, if present
+     *   (2) driver name [.instance]
+     *   (3) driver alias [.instance], if present
      */
     QLIST_FOREACH(dev, &bus->children, sibling) {
         if (dev->id  &&  strcmp(dev->id, elem) == 0) {
             return dev;
         }
     }
+
+    if (sscanf(elem, "%127[^.].%u", buf, &instance) == 2) {
+        elem = buf;
+    } else {
+        instance = 0;
+    }
+
+    n = 0;
     QLIST_FOREACH(dev, &bus->children, sibling) {
-        if (strcmp(dev->info->name, elem) == 0) {
+        if (strcmp(dev->info->name, elem) == 0 && n++ == instance) {
             return dev;
         }
     }
+
+    n = 0;
     QLIST_FOREACH(dev, &bus->children, sibling) {
-        if (dev->info->alias && strcmp(dev->info->alias, elem) == 0) {
+        if (dev->info->alias && strcmp(dev->info->alias, elem) == 0 &&
+            n++ == instance) {
             return dev;
         }
     }
-- 
1.6.0.2