spmi: Add helper to get a parent SPMI device

Drivers that register a SPMI sub-device as a platform_driver are
not guaranteed to have a SPMI device as their parent: add a new
helper `spmi_get_parent_spmi_device()` that takes a struct device
and checks if there's a parent, and if that parent is actually a
SPMI device by checking if its device type matches with SPMI: if
so, returns a pointer to the relative struct spmi_device without
incrementing any refcount.

As a note, in the specific case of using this helper to retrieve
a SPMI subdevice's parent, the spmi_subdevice_alloc_and_add()
function does actually call device_add(), which will already take
care of raising the refcount of the associated parent device.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

0 files changed, 0 insertions, 0 deletions