Hello AngeloGioacchino,

On Tue, Sep 16, 2025 at 10:44:39AM +0200, AngeloGioacchino Del Regno wrote:

+/**
+ * spmi_subdevice_alloc_and_add(): Allocate and add a new SPMI sub-device
+ * @sparent:	SPMI parent device with previously registered SPMI controller
+ *
+ * Returns:
+ * Pointer to newly allocated SPMI sub-device for success or negative ERR_PTR.
+ */
+struct spmi_subdevice *spmi_subdevice_alloc_and_add(struct spmi_device *sparent)
+{
+	struct spmi_subdevice *sub_sdev;
+	struct spmi_device *sdev;
+	int ret;
+
+	sub_sdev = kzalloc(sizeof(*sub_sdev), GFP_KERNEL);
+	if (!sub_sdev)
+		return ERR_PTR(-ENOMEM);
+
+	ret = ida_alloc(&spmi_subdevice_ida, GFP_KERNEL);
+	if (ret < 0) {
+		kfree(sub_sdev);
+		return ERR_PTR(ret);
+	}
+
+	sdev = &sub_sdev->sdev;
+	sdev->ctrl = sparent->ctrl;
+	device_initialize(&sdev->dev);
+	sdev->dev.parent = &sparent->dev;
+	sdev->dev.bus = &spmi_bus_type;
+	sdev->dev.type = &spmi_subdev_type;
+
+	sub_sdev->devid = ret;
+	sdev->usid = sparent->usid;
+
+	ret = dev_set_name(&sdev->dev, "%d-%02x.%d.auto",
+			   sdev->ctrl->nr, sdev->usid, sub_sdev->devid);

If I understand correctly sub_sdev->devid is globally unique. I wonder
if a namespace that is specific to the parent spmi device would be more
sensible?!

+	if (ret)
+		goto err_put_dev;
+
+	ret = device_add(&sdev->dev);
+	if (ret) {
+		dev_err(&sdev->dev, "Can't add %s, status %d\n",

I'd use %pe instead of %d here.

+			dev_name(&sdev->dev), ret);
+		goto err_put_dev;
+	}
+
+	return sub_sdev;
+
+err_put_dev:
+	put_device(&sdev->dev);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_NS_GPL(spmi_subdevice_alloc_and_add, "SPMI");
+

Best regards
Uwe