rust: pwm: Add UnregisteredChip wrapper around Chip

The `pwm::Registration::register` function provides no guarantee that the
function isn't called twice with the same pwm chip, which is considered
unsafe.

Add `pwm::UnregisteredChip` as wrapper around `pwm::Chip`.
Implement `pwm::UnregisteredChip::register` for the registration. This
function takes ownership of `pwm::UnregisteredChip` and therefore
guarantees that the registration can't be called twice on the same pwm
chip.

Signed-off-by: Markus Probst <markus.probst@posteo.de>
Tested-by: Michal Wilczynski <m.wilczynski@samsung.com>
Acked-by: Michal Wilczynski <m.wilczynski@samsung.com>
Link: https://patch.msgid.link/20251202-pwm_safe_register-v2-1-7a2e0d1e287f@posteo.de
[ukleinek: fixes a typo that Michal pointed out during review]
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/pwm/pwm_th1520.rs b/drivers/pwm/pwm_th1520.rs
index e3b7e77356fc..71b80761ec31 100644
--- a/drivers/pwm/pwm_th1520.rs
+++ b/drivers/pwm/pwm_th1520.rs
@@ -372,7 +372,7 @@ impl platform::Driver for Th1520PwmPlatformDriver {
             }),
         )?;
 
-        pwm::Registration::register(dev, chip)?;
+        chip.register()?;
 
         Ok(Th1520PwmPlatformDriver)
     }