device_get_property: add a HANDLE case

This will resolve a reference and return the appropriate handle, a node
on the simplebus or an ACPI_HANDLE for ACPI.  For now we do not try to
further abstract the return type.

MFC after:	2 weeks
Reviewed by:	mw
Differential Revision: https://reviews.freebsd.org/D36793

share/man/man9/device_get_property.9

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 18, 2022
+.Dd September 29, 2022
 .Dt DEVICE_GET_PROPERTY 9
 .Os
 .Sh NAME
@@ -54,6 +54,9 @@ Currently the following types are supported:
 The underlying property is a string of bytes.
 .It Dv DEVICE_PROP_ANY
 Wildcard property type.
+.It Dv DEVICE_PROP_HANDLE
+Following a reference the underlying property is a handle of the
+respective bus.
 .It Dv DEVICE_PROP_UINT32
 The underlying property is an array of unsigned 32 bit integers.
 The

sys/dev/acpica/acpi.c

@@ -1923,6 +1923,35 @@ acpi_find_dsd(struct acpi_device *ad)
 	return (AE_NOT_FOUND);
 }
 
+static ssize_t
+acpi_bus_get_prop_handle(const ACPI_OBJECT *hobj, void *propvalue, size_t size)
+{
+	ACPI_OBJECT *pobj;
+	ACPI_HANDLE h;
+
+	if (hobj->Type != ACPI_TYPE_PACKAGE)
+		goto err;
+	if (hobj->Package.Count != 1)
+		goto err;
+
+	pobj = &hobj->Package.Elements[0];
+	if (pobj == NULL)
+		goto err;
+	if (pobj->Type != ACPI_TYPE_LOCAL_REFERENCE)
+		goto err;
+
+	h = acpi_GetReference(NULL, pobj);
+	if (h == NULL)
+		goto err;
+
+	if (propvalue != NULL && size >= sizeof(ACPI_HANDLE))
+		*(ACPI_HANDLE *)propvalue = h;
+	return (sizeof(ACPI_HANDLE));
+
+err:
+	return (-1);
+}
+
 static ssize_t
 acpi_bus_get_prop(device_t bus, device_t child, const char *propname,
     void *propvalue, size_t size, device_property_type_t type)
@@ -1941,6 +1970,8 @@ acpi_bus_get_prop(device_t bus, device_t child, const char *propname,
 	case DEVICE_PROP_UINT32:
 	case DEVICE_PROP_UINT64:
 		break;
+	case DEVICE_PROP_HANDLE:
+		return (acpi_bus_get_prop_handle(obj, propvalue, size));
 	default:
 		return (-1);
 	}
@@ -1972,6 +2003,22 @@ acpi_bus_get_prop(device_t bus, device_t child, const char *propname,
 			    MIN(size, obj->Buffer.Length));
 		return (obj->Buffer.Length);
 
+	case ACPI_TYPE_PACKAGE:
+		if (propvalue != NULL && size >= sizeof(ACPI_OBJECT *)) {
+			*((ACPI_OBJECT **) propvalue) =
+			    __DECONST(ACPI_OBJECT *, obj);
+		}
+		return (sizeof(ACPI_OBJECT *));
+
+	case ACPI_TYPE_LOCAL_REFERENCE:
+		if (propvalue != NULL && size >= sizeof(ACPI_HANDLE)) {
+			ACPI_HANDLE h;
+
+			h = acpi_GetReference(NULL,
+			    __DECONST(ACPI_OBJECT *, obj));
+			memcpy(propvalue, h, sizeof(ACPI_HANDLE));
+		}
+		return (sizeof(ACPI_HANDLE));
 	default:
 		return (0);
 	}

sys/dev/fdt/simplebus.c

@@ -357,7 +357,7 @@ static ssize_t
 simplebus_get_property(device_t bus, device_t child, const char *propname,
     void *propvalue, size_t size, device_property_type_t type)
 {
-	phandle_t node = ofw_bus_get_node(child);
+	phandle_t node, xref;
 	ssize_t ret, i;
 	uint32_t *buffer;
 	uint64_t val;
@@ -367,11 +367,13 @@ simplebus_get_property(device_t bus, device_t child, const char *propname,
 	case DEVICE_PROP_BUFFER:
 	case DEVICE_PROP_UINT32:
 	case DEVICE_PROP_UINT64:
+	case DEVICE_PROP_HANDLE:
 		break;
 	default:
 		return (-1);
 	}
 
+	node = ofw_bus_get_node(child);
 	if (propvalue == NULL || size == 0)
 		return (OF_getproplen(node, propname));
 
@@ -402,7 +404,20 @@ simplebus_get_property(device_t bus, device_t child, const char *propname,
 			((uint64_t *)buffer)[i / 2] = val;
 		}
 		return (ret);
-	 }
+	}
+
+	if (type == DEVICE_PROP_HANDLE) {
+		if (size < sizeof(node))
+			return (-1);
+		ret = OF_getencprop(node, propname, &xref, sizeof(xref));
+		if (ret <= 0)
+			return (ret);
+
+		node = OF_node_from_xref(xref);
+		if (propvalue != NULL)
+			*(uint32_t *)propvalue = node;
+		return (ret);
+	}
 
 	return (OF_getprop(node, propname, propvalue, size));
 }

sys/kern/subr_bus.c

@@ -2226,6 +2226,7 @@ device_get_property(device_t dev, const char *prop, void *val, size_t sz,
 	switch (type) {
 	case DEVICE_PROP_ANY:
 	case DEVICE_PROP_BUFFER:
+	case DEVICE_PROP_HANDLE:	/* Size checks done in implementation. */
 		break;
 	case DEVICE_PROP_UINT32:
 		if (sz % 4 != 0)

sys/sys/bus.h

@@ -72,6 +72,7 @@ typedef enum device_property_type {
 	DEVICE_PROP_BUFFER = 1,
 	DEVICE_PROP_UINT32 = 2,
 	DEVICE_PROP_UINT64 = 3,
+	DEVICE_PROP_HANDLE = 4,
 } device_property_type_t;
 
 /**