Re: [PATCH v1 1/1] hw/i2c/aspeed: Introduce 'bus-label' to customize bus naming

[Cédric Le Goater]

Hello Nabih,

On 1/15/26 00:11, Nabih Estefan wrote:

On Mon, Jan 12, 2026 at 12:38 AM Kane Chen via qemu development
<qemu-devel@nongnu.org> wrote:

From: Kane-Chen-AS <kane_c...@aspeedtech.com>

On some Aspeed-based machines, multiple I2C controllers may exist
across different components, such as the primary SoC and an external
IO expander or co-processor (e.g., AST1700). Using the current static
naming convention results in object name conflicts when multiple
controllers attempt to instantiate buses with the same ID.

This patch introduces a 'bus-label' property for the Aspeed I2C
controller. This allows higher-level layers, such as the SoC realize
function, to provide a unique identifier for the buses. The I2C bus
object name is then constructed using this label (e.g., "ioexp0.0"
instead of the default "aspeed.i2c.bus.0").

This enhancement ensures unique bus identifiers across the system and
resolves naming conflicts in multi-controller configurations.

Signed-off-by: Kane-Chen-AS <kane_c...@aspeedtech.com>

Signed-off-by: Nabih Estefan <nabiheste...@google.com>

Did you mean 'Reviewed-by' ?

Thanks,

C.

Tested-by: Nabih Estefan <nabiheste...@google.com>

This is basically a rework of the bus-label patches I already tested
and we're carrying for AST1700, re-tested just in case, and everything
still looks good!

Thank you Kane!

-Nabih

---
  include/hw/i2c/aspeed_i2c.h |  2 ++
  hw/i2c/aspeed_i2c.c         | 27 +++++++++++++++++++++------
  2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/include/hw/i2c/aspeed_i2c.h b/include/hw/i2c/aspeed_i2c.h
index ffcff2580f..68bd138026 100644
--- a/include/hw/i2c/aspeed_i2c.h
+++ b/include/hw/i2c/aspeed_i2c.h
@@ -252,6 +252,7 @@ struct AspeedI2CBus {
      MemoryRegion mr_pool;

      I2CBus *bus;
+    char *name;
      uint8_t id;
      qemu_irq irq;

@@ -269,6 +270,7 @@ struct AspeedI2CState {
      uint32_t intr_status;
      uint32_t ctrl_global;
      uint32_t new_clk_divider;
+    char *bus_label;
      MemoryRegion pool_iomem;
      uint8_t share_pool[ASPEED_I2C_SHARE_POOL_SIZE];

diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
index 1b8ac561c3..7cf92423c7 100644
--- a/hw/i2c/aspeed_i2c.c
+++ b/hw/i2c/aspeed_i2c.c
@@ -1215,9 +1215,16 @@ static void aspeed_i2c_realize(DeviceState *dev, Error 
**errp)
                            "aspeed.i2c", aic->mem_size);
      sysbus_init_mmio(sbd, &s->iomem);

+    /* default value */
+    if (!s->bus_label) {
+        s->bus_label = g_strdup(TYPE_ASPEED_I2C_BUS);
+    }
+
      for (i = 0; i < aic->num_busses; i++) {
          Object *bus = OBJECT(&s->busses[i]);
          int offset = i < aic->gap ? 1 : 5;
+        g_autofree char *name = g_strdup_printf("%s.%d",
+                                                s->bus_label, i);

          if (!object_property_set_link(bus, "controller", OBJECT(s), errp)) {
              return;
@@ -1227,6 +1234,10 @@ static void aspeed_i2c_realize(DeviceState *dev, Error 
**errp)
              return;
          }

+        if (!object_property_set_str(bus, "bus-name", name, errp)) {
+            return;
+        }
+
          if (!sysbus_realize(SYS_BUS_DEVICE(bus), errp)) {
              return;
          }
@@ -1263,6 +1274,7 @@ static void aspeed_i2c_realize(DeviceState *dev, Error 
**errp)
  static const Property aspeed_i2c_properties[] = {
      DEFINE_PROP_LINK("dram", AspeedI2CState, dram_mr,
                       TYPE_MEMORY_REGION, MemoryRegion *),
+    DEFINE_PROP_STRING("bus-label", AspeedI2CState, bus_label),
  };

  static void aspeed_i2c_class_init(ObjectClass *klass, const void *data)
@@ -1423,24 +1435,26 @@ static void aspeed_i2c_bus_realize(DeviceState *dev, 
Error **errp)
  {
      AspeedI2CBus *s = ASPEED_I2C_BUS(dev);
      AspeedI2CClass *aic;
-    g_autofree char *name = g_strdup_printf(TYPE_ASPEED_I2C_BUS ".%d", s->id);
-    g_autofree char *pool_name = g_strdup_printf("%s.pool", name);
+    g_autofree char *pool_name = NULL;

-    if (!s->controller) {
-        error_setg(errp, TYPE_ASPEED_I2C_BUS ": 'controller' link not set");
+    if (!s->controller || !s->name) {
+        error_setg(errp, TYPE_ASPEED_I2C_BUS
+                   ": 'controller' or 'bus-name' not set");
          return;
      }

+    pool_name = g_strdup_printf("%s.pool", s->name);
+
      aic = ASPEED_I2C_GET_CLASS(s->controller);

      sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq);

-    s->bus = i2c_init_bus(dev, name);
+    s->bus = i2c_init_bus(dev, s->name);
      s->slave = i2c_slave_create_simple(s->bus, TYPE_ASPEED_I2C_BUS_SLAVE,
                                         0xff);

      memory_region_init_io(&s->mr, OBJECT(s), &aspeed_i2c_bus_ops,
-                          s, name, aic->reg_size);
+                          s, s->name, aic->reg_size);
      sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mr);

      memory_region_init_io(&s->mr_pool, OBJECT(s), &aspeed_i2c_bus_pool_ops,
@@ -1452,6 +1466,7 @@ static const Property aspeed_i2c_bus_properties[] = {
      DEFINE_PROP_UINT8("bus-id", AspeedI2CBus, id, 0),
      DEFINE_PROP_LINK("controller", AspeedI2CBus, controller, TYPE_ASPEED_I2C,
                       AspeedI2CState *),
+    DEFINE_PROP_STRING("bus-name", AspeedI2CBus, name),
  };

  static void aspeed_i2c_bus_class_init(ObjectClass *klass, const void *data)
--
2.43.0