Re: [net-next PATCH v4 09/15] device property: Introduce fwnode_get_id()

[Rafael J. Wysocki]

On Fri, Jan 22, 2021 at 4:46 PM Calvin Johnson
<calvin.johnson@xxxxxxxxxxx> wrote:
>
> 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 <calvin.johnson@xxxxxxxxxxx>
> ---
>
> 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;

Please don't return -EINVAL from here, because this means "invalid
argument" to the caller, but there may be nothing wrong with the
fwnode and id pointers.

I would return -ENODATA instead.

> +               *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
>