gpu: nvgpu: create a wrapper over sync_fences

This patch constructs an abstraction to hide the sync_fence
functionality from the common code. struct nvgpu_os_fence acts as an
abstraction for struct sync_fence.

struct nvgpu_os_fence consists of an ops structure named nvgpu_os_fence_ops
which contains an API to do pushbuffer programming to generate wait
commands for the fence.

The current implementation of nvgpu only allows for wait method on a
sync_fence which was generated using a similar backend(i.e. either
Nvhost Syncpoints or Semaphores). In this patch, a
generic API is introduced which will decide the type of the underlying
implementation of the struct nvgpu_os_fence at runtime and run the
corresponding wait implementation on it.

This patch changes the channel_sync_gk20a's semaphore specific
implementation to use the abstract API. A subsequent patch will make
the changes for the nvhost_syncpoint based implementations as well.

JIRA NVGPU-66

Change-Id: If6675bfde5885c3d15d2ca380bb6c7c0e240e734
Signed-off-by: Debarshi Dutta <ddutta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1667218
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 111 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/os_fence.h b/drivers/gpu/nvgpu/include/nvgpu/os_fence.h
new file mode 100644
index 00000000..c8d24fc2
--- /dev/null
+++ b/drivers/gpu/nvgpu/include/nvgpu/os_fence.h
@@ -0,0 +1,111 @@
+/*
+ * nvgpu os fence
+ *
+ * Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef __NVGPU_OS_FENCE__
+#define __NVGPU_OS_FENCE__
+
+struct nvgpu_semaphore;
+struct channel_gk20a;
+struct priv_cmd_entry;
+
+/*
+ * struct nvgpu_os_fence adds an abstraction to the earlier Android Sync
+ * Framework, specifically the sync-fence mechanism and the newer DMA sync
+ * APIs from linux-4.9. This abstraction provides the high-level definition
+ * as well as APIs that can be used by other OSes in future to have their own
+ * alternatives for the sync-framework.
+ */
+struct nvgpu_os_fence;
+
+/*
+ * struct nvgpu_os_fence depends on the following ops structure
+ */
+struct nvgpu_os_fence_ops {
+        /*
+         * This API is used to iterate through multiple fence points within the
+         * fence and program the pushbuffer method for wait command.
+         */
+        int (*program_waits)(struct nvgpu_os_fence *s,
+                struct priv_cmd_entry *wait_cmd,
+                struct channel_gk20a *c,
+                int max_wait_cmds);
+
+        /*
+         * This should be the last operation on the OS fence. The
+         * OS fence acts as a place-holder for the underlying fence
+         * implementation e.g. sync_fences. For each construct/fdget call
+         * there needs to be a drop_ref call. This reduces a reference count
+         * for the underlying sync_fence.
+         */
+        void (*drop_ref)(struct nvgpu_os_fence *s);
+};
+
+/*
+ * The priv structure here is used to contain the struct sync_fence
+ * for LINUX_VERSION <= 4.9 and dma_fence for LINUX_VERSION > 4.9
+ */
+struct nvgpu_os_fence {
+        void *priv;
+        struct gk20a *g;
+        const struct nvgpu_os_fence_ops *ops;
+};
+
+/*
+ * This API is used to validate the nvgpu_os_fence
+ */
+static inline int nvgpu_os_fence_is_initialized(struct nvgpu_os_fence *fence)
+{
+        return (fence->ops != NULL);
+}
+
+#ifdef CONFIG_SYNC
+
+int nvgpu_os_fence_sema_create(
+        struct nvgpu_os_fence *fence_out,
+        struct channel_gk20a *c,
+        struct nvgpu_semaphore *sema);
+
+int nvgpu_os_fence_fdget(
+        struct nvgpu_os_fence *fence_out,
+        struct channel_gk20a *c, int fd);
+
+#else
+
+static inline int nvgpu_os_fence_sema_create(
+        struct nvgpu_os_fence *fence_out,
+        struct channel_gk20a *c,
+        struct nvgpu_semaphore *sema)
+{
+        return -ENOSYS;
+}
+static inline int nvgpu_os_fence_fdget(
+        struct nvgpu_os_fence *fence_out,
+        struct channel_gk20a *c, int fd)
+{
+        return -ENOSYS;
+}
+
+#endif /* CONFIG_SYNC */
+
+#endif /* __NVGPU_OS_FENCE__ */