drm/amdgpu: Implement a new userqueue fence driver

Developed a userqueue fence driver for the userqueue process shared
BO synchronization.

Create a dma fence having write pointer as the seqno and allocate a
seq64 memory for each user queue process and feed this memory address
into the firmware/hardware, thus the firmware writes the read pointer
into the given address when the process completes it execution.
Compare wptr and rptr, if rptr >= wptr, signal the fences for the waiting
process to consume the buffers.

v2: Worked on review comments from Christian for the following
    modifications

    - Add wptr as sequence number into the fence
    - Add a reference count for the fence driver
    - Add dma_fence_put below the list_del as it might
      frees the userq fence.
    - Trim unnecessary code in interrupt handler.
    - Check dma fence signaled state in dma fence creation
      function for a potential problem of hardware completing
      the job processing beforehand.
    - Add necessary locks.
    - Create a list and process all the unsignaled fences.
    - clean up fences in destroy function.
    - implement .signaled callback function

v3: Worked on review comments from Christian
    - Modify naming convention for reference counted objects
    - Fix fence driver reference drop issue
    - Drop amdgpu_userq_fence_driver_process() function return value

v4: Worked on review comments from Christian
    - Moved fence driver allocation into amdgpu_userq_fence_driver_alloc()
    - Added detail doc mentioning the differences b/w
      two spinlocks declared.

v5: Worked on review comments from Christian
    - Check before upcast and remove local variable
    - Add error handling in fence_drv alloc function.
    - Move rptr read fn outside of the loop and remove WARN_ON in
      destroy function.

v6:
  - clear the seq64 memory in user fence driver(Christian)
  - fix for the wptr va bo mapping(Christian)
  - move the fence_drv xa entry erase code from the interrupt handler
    into user fence destroy function

Signed-off-by: Arunpravin Paneer Selvam <[email protected]>
Reviewed-by: Christian König <[email protected]>
Suggested-by: Christian König <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

1 files changed, 69 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h
new file mode 100644
index 000000000000..c3e04cdbb9e7
--- /dev/null
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright 2023 Advanced Micro Devices, Inc.
+ *
+ * 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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 __AMDGPU_USERQ_FENCE_H__
+#define __AMDGPU_USERQ_FENCE_H__
+
+#include <linux/types.h>
+
+#include "amdgpu_userqueue.h"
+
+struct amdgpu_userq_fence {
+	struct dma_fence base;
+	/*
+	 * This lock is necessary to synchronize the
+	 * userqueue dma fence operations.
+	 */
+	spinlock_t lock;
+	struct list_head link;
+	struct amdgpu_userq_fence_driver *fence_drv;
+};
+
+struct amdgpu_userq_fence_driver {
+	struct kref refcount;
+	u64 gpu_addr;
+	u64 *cpu_addr;
+	u64 context;
+	/*
+	 * This lock is necesaary to synchronize the access
+	 * to the fences list by the fence driver.
+	 */
+	spinlock_t fence_list_lock;
+	struct list_head fences;
+	struct amdgpu_device *adev;
+	char timeline_name[TASK_COMM_LEN];
+};
+
+int amdgpu_userq_fence_slab_init(void);
+void amdgpu_userq_fence_slab_fini(void);
+int amdgpu_userq_fence_create(struct amdgpu_usermode_queue *userq,
+			      u64 seq, struct dma_fence **f);
+void amdgpu_userq_fence_driver_get(struct amdgpu_userq_fence_driver *fence_drv);
+void amdgpu_userq_fence_driver_put(struct amdgpu_userq_fence_driver *fence_drv);
+int amdgpu_userq_fence_driver_alloc(struct amdgpu_device *adev,
+				    struct amdgpu_usermode_queue *userq);
+void amdgpu_userq_fence_driver_process(struct amdgpu_userq_fence_driver *fence_drv);
+void amdgpu_userq_fence_driver_destroy(struct kref *ref);
+
+#endif