gsp-phys: backend session API skeleton (P0, inert)

1 files changed, 27 insertions, 0 deletions

diff --git a/kernel/gsp_phys_gpu.h b/kernel/gsp_phys_gpu.h
index b8a1955..36532a5 100644
--- a/kernel/gsp_phys_gpu.h
+++ b/kernel/gsp_phys_gpu.h
@@ -12,4 +12,31 @@ int gsp_phys_gpu_claim(void);
 void gsp_phys_gpu_release(void);
 void __iomem *gsp_phys_gpu_bar0(void);
 
+/*
+ * Backend session state (P0 skeleton; one physical GPU, one live claim).
+ * OFF until a start claims the device; READY is the only state in which live
+ * RPC forwarding is legal. The refcount and owner flag decide who releases:
+ * the load-time module-owned claim is joined, never released, by a stop().
+ */
+enum gsp_phys_backend_state {
+	GSP_PHYS_BACKEND_OFF = 0,
+	GSP_PHYS_BACKEND_CLAIMING,
+	GSP_PHYS_BACKEND_BOOTING,
+	GSP_PHYS_BACKEND_READY,
+	GSP_PHYS_BACKEND_STOPPING,
+};
+
+/*
+ * Refcounted session start/stop around gsp_phys_gpu_claim()/_release(); safe
+ * (and idempotent) in any state. The generation counter is bumped when the
+ * session leaves READY; a forward that captured the previous value re-checks
+ * it under gsp_phys_rm_lock and refuses, so a stop cannot race an in-flight
+ * forward. The lock itself stays private to gsp_phys_gpu.c; the state and
+ * generation accessors are lock-free reads for use from the RPC path.
+ */
+int gsp_phys_backend_start(void);
+void gsp_phys_backend_stop(void);
+int gsp_phys_backend_state(void);
+u32 gsp_phys_backend_generation(void);
+
 #endif /* GSP_PHYS_GPU_H */