soc: apple: rtkit: Add function to poweroff

Add a function to put a co-processor into the lowest possible power
state from which recovery usually isn't possible without a full SoC
reset. This is required for the USB4/Thunderbolt co-processors which
can be restarted since the entire USB4 root complex can be completely
reset independently of the rest of the SoC.

Reviewed-by: Janne Grunau <j@jannau.net>
Link: https://patch.msgid.link/20260117-apple-rtkit-poweroff-v2-1-b882a180e44d@kernel.org
Signed-off-by: Sven Peter <sven@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/soc/apple/rtkit.h b/include/linux/soc/apple/rtkit.h
index 736f53018017..bda3c528b515 100644
--- a/include/linux/soc/apple/rtkit.h
+++ b/include/linux/soc/apple/rtkit.h
@@ -126,6 +126,13 @@ int apple_rtkit_wake(struct apple_rtkit *rtk);
 int apple_rtkit_shutdown(struct apple_rtkit *rtk);
 
 /*
+ * Put the co-processor into the lowest power state. Note that it usually
+ * is not possible to recover from this state without a full SoC reset.
+ */
+
+int apple_rtkit_poweroff(struct apple_rtkit *rtk);
+
+/*
  * Put the co-processor into idle mode
  */
 int apple_rtkit_idle(struct apple_rtkit *rtk);