Hi Laurent,

Thanks for reviewing.
On Tue, Dec 15, 2020 at 07:00:28PM +0200, Laurent Pinchart wrote:

Hi Calvin,

Thank you for the patch.

On Tue, Dec 15, 2020 at 10:13:11PM +0530, Calvin Johnson wrote:

quoted

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

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

Changes in v2: None

 drivers/base/property.c  | 26 ++++++++++++++++++++++++++
 include/linux/property.h |  1 +
 2 files changed, 27 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 4c43d30145c6..1c50e17ae879 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c

@@ -580,6 +580,32 @@ 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
+ *

Is the concept of fwnode ID documented clearly somewhere ? I think this
function should otherwise have more documentation, at least to explain
what the ID is.

Agree. Will add more info here.

quoted

+ * Returns 0 on success or a negative errno.
+ */
+int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id)
+{
+	unsigned long long adr;
+	acpi_status status;
+
+	if (is_of_node(fwnode)) {
+		return of_property_read_u32(to_of_node(fwnode), "reg", id);
+	} else if (is_acpi_node(fwnode)) {
+		status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwnode),
+					       METHOD_NAME__ADR, NULL, &adr);
+		if (ACPI_FAILURE(status))
+			return -ENODATA;

Would it make sense to standardize error codes ? of_property_read_u32()
can return -EINVAL, -ENODATA or -EOVERFLOW. I don't think the caller of
this function would be very interested to tell those three cases apart.
Maybe we should return -EINVAL in all error cases ? Or maybe different
error codes to mean "the backend doesn't support the concept of IDs",
and "the device doesn't have an ID" ?

I think it make sense to return just -EINVAL. Will take care in v3.

Thanks
Calvin