Using fwnode_get_id(), get the reg property value for DT node
or get the _ADR object value for ACPI node.

Signed-off-by: Calvin Johnson <redacted>
---

Changes in v4:
- Improve code structure to handle all cases

Changes in v3:
- Modified to retrieve reg property value for ACPI as well
- Resolved compilation issue with CONFIG_ACPI = n
- Added more info into documentation

Changes in v2: None

 drivers/base/property.c  | 34 ++++++++++++++++++++++++++++++++++
 include/linux/property.h |  1 +
 2 files changed, 35 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 35b95c6ac0c6..f0581bbf7a4b 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c

@@ -580,6 +580,40 @@ const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode)
        return fwnode_call_ptr_op(fwnode, get_name_prefix);
 }

+/**
+ * fwnode_get_id - Get the id of a fwnode.
+ * @fwnode: firmware node
+ * @id: id of the fwnode
+ *
+ * This function provides the id of a fwnode which can be either
+ * DT or ACPI node. For ACPI, "reg" property value, if present will
+ * be provided or else _ADR value will be provided.
+ * Returns 0 on success or a negative errno.
+ */
+int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id)
+{
+#ifdef CONFIG_ACPI
+       unsigned long long adr;
+       acpi_status status;
+#endif
+       int ret;
+
+       ret = fwnode_property_read_u32(fwnode, "reg", id);
+       if (ret) {
+#ifdef CONFIG_ACPI
+               status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwnode),
+                                              METHOD_NAME__ADR, NULL, &adr);
+               if (ACPI_FAILURE(status))
+                       return -EINVAL;

+               *id = (u32)adr;
+#else
+               return ret;
+#endif
+       }
+       return 0;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_id);
+
 /**
  * fwnode_get_parent - Return parent firwmare node
  * @fwnode: Firmware whose parent is retrieved

diff --git a/include/linux/property.h b/include/linux/property.h
index 0a9001fe7aea..3f41475f010b 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h

@@ -82,6 +82,7 @@ struct fwnode_handle *fwnode_find_reference(const struct fwnode_handle *fwnode,

 const char *fwnode_get_name(const struct fwnode_handle *fwnode);
 const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode);
+int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id);
 struct fwnode_handle *fwnode_get_parent(const struct fwnode_handle *fwnode);
 struct fwnode_handle *fwnode_get_next_parent(
        struct fwnode_handle *fwnode);
--

2.17.1