Re: [net-next PATCH v3 09/15] device property: Introduce fwnode_get_id()

On Tue, Jan 12, 2021 at 4:47 PM Andy Shevchenko
[off-list ref] wrote:

On Tue, Jan 12, 2021 at 3:42 PM Calvin Johnson
[off-list ref] wrote:

quoted

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 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  | 33 +++++++++++++++++++++++++++++++++
 include/linux/property.h |  1 +
 2 files changed, 34 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 35b95c6ac0c6..2d51108cb936 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c

@@ -580,6 +580,39 @@ 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 && is_acpi_node(fwnode)))
+               return 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;

Shouldn't be

       return 0;
#else
       return -EINVAL;
#endif

?

Yes, it's a theoretical case when is_acpi_node() returns true when
CONFIG_ACPI=n.

How so?  is_acpi_node() is defined as a static inline returning false then.