Re: [PATCH v2 07/17] hw/arm/aspeed: Attach UART device to AST1700 model

[Cédric Le Goater]

Hi,

This change appears complex due to the use of routine
qdev_set_legacy_instance_id(). It was introduced 15 years ago
by commit 4d2ffa08b601 ("vmstate: Add support for alias ID"),
for the PC world AIUI.

Adding Jan, Peter, Fabiano for feedback on the current relevance
of qdev_set_legacy_instance_id(), particularly in the ARM/BMC world.
I feel we could get rid of it and simplify this patch.

Thanks,

C.





On 11/5/25 04:58, Kane Chen wrote:

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

Connect the UART controller to the AST1700 model by mapping its MMIO
region.

Signed-off-by: Kane-Chen-AS <kane_c...@aspeedtech.com>
---
  include/hw/misc/aspeed_ast1700.h |  2 ++
  hw/arm/aspeed_ast27x0.c          |  2 ++
  hw/misc/aspeed_ast1700.c         | 26 ++++++++++++++++++++++++++
  3 files changed, 30 insertions(+)

diff --git a/include/hw/misc/aspeed_ast1700.h b/include/hw/misc/aspeed_ast1700.h
index c2bea11346..e105ceb027 100644
--- a/include/hw/misc/aspeed_ast1700.h
+++ b/include/hw/misc/aspeed_ast1700.h
@@ -28,8 +28,10 @@ struct AspeedAST1700SoCState {
      SysBusDevice parent_obj;

MemoryRegion iomem;

+    hwaddr mapped_base;

AspeedLTPIState ltpi;

+    SerialMM uart;
  };

#endif /* ASPEED_AST1700_H */

diff --git a/hw/arm/aspeed_ast27x0.c b/hw/arm/aspeed_ast27x0.c
index 11625e165a..7151feb35d 100644
--- a/hw/arm/aspeed_ast27x0.c
+++ b/hw/arm/aspeed_ast27x0.c
@@ -1070,6 +1070,8 @@ static void aspeed_soc_ast2700_realize(DeviceState *dev, 
Error **errp)

/* IO Expander */

      for (i = 0; i < sc->ioexp_num; i++) {
+        qdev_prop_set_uint64(DEVICE(&s->ioexp[i]), "mapped-base",
+                             sc->memmap[ASPEED_DEV_LTPI_IO0 + i]);
          if (!sysbus_realize(SYS_BUS_DEVICE(&s->ioexp[i]), errp)) {
              return;
          }
diff --git a/hw/misc/aspeed_ast1700.c b/hw/misc/aspeed_ast1700.c
index 0ca2b90ff0..1c2d367cdb 100644
--- a/hw/misc/aspeed_ast1700.c
+++ b/hw/misc/aspeed_ast1700.c
@@ -18,22 +18,39 @@
  #define AST2700_SOC_LTPI_SIZE        0x01000000

enum {

+    ASPEED_AST1700_DEV_UART12,
      ASPEED_AST1700_DEV_LTPI_CTRL,
  };

static const hwaddr aspeed_ast1700_io_memmap[] = {

+    [ASPEED_AST1700_DEV_UART12]    =  0x00C33B00,
      [ASPEED_AST1700_DEV_LTPI_CTRL] =  0x00C34000,
  };
  static void aspeed_ast1700_realize(DeviceState *dev, Error **errp)
  {
      AspeedAST1700SoCState *s = ASPEED_AST1700(dev);
      SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    hwaddr uart_base;

/* Occupy memory space for all controllers in AST1700 */

      memory_region_init(&s->iomem, OBJECT(s), TYPE_ASPEED_AST1700,
                         AST2700_SOC_LTPI_SIZE);
      sysbus_init_mmio(sbd, &s->iomem);

+ /* UART */

+    uart_base = s->mapped_base +
+               aspeed_ast1700_io_memmap[ASPEED_AST1700_DEV_UART12];
+    qdev_prop_set_uint8(DEVICE(&s->uart), "regshift", 2);
+    qdev_prop_set_uint32(DEVICE(&s->uart), "baudbase", 38400);
+    qdev_set_legacy_instance_id(DEVICE(&s->uart), uart_base, 2);
+    qdev_prop_set_uint8(DEVICE(&s->uart), "endianness", DEVICE_LITTLE_ENDIAN);
+    if (!sysbus_realize(SYS_BUS_DEVICE(&s->uart), errp)) {
+        return;
+    }
+    memory_region_add_subregion(&s->iomem,
+                        aspeed_ast1700_io_memmap[ASPEED_AST1700_DEV_UART12],
+                        sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->uart), 0));
+
      /* LTPI controller */
      if (!sysbus_realize(SYS_BUS_DEVICE(&s->ltpi), errp)) {
          return;
@@ -47,6 +64,10 @@ static void aspeed_ast1700_instance_init(Object *obj)
  {
      AspeedAST1700SoCState *s = ASPEED_AST1700(obj);

+ /* UART */

+    object_initialize_child(obj, "uart[*]", &s->uart,
+                            TYPE_SERIAL_MM);
+
      /* LTPI controller */
      object_initialize_child(obj, "ltpi-ctrl",
                              &s->ltpi, TYPE_ASPEED_LTPI);
@@ -54,11 +75,16 @@ static void aspeed_ast1700_instance_init(Object *obj)
      return;
  }

+static const Property aspeed_ast1700_props[] = {

+    DEFINE_PROP_UINT64("mapped-base", AspeedAST1700SoCState, mapped_base, 0),
+};
+
  static void aspeed_ast1700_class_init(ObjectClass *klass, const void *data)
  {
      DeviceClass *dc = DEVICE_CLASS(klass);

dc->realize = aspeed_ast1700_realize;

+    device_class_set_props(dc, aspeed_ast1700_props);
  }

static const TypeInfo aspeed_ast1700_info = {