drm/amdgpu: add usermode queue base code

This patch adds IP independent skeleton code for amdgpu
usermode queue. It contains:
- A new files with init functions of usermode queues.
- A queue context manager in driver private data.

V1: Worked on design review comments from RFC patch series:
(https://patchwork.freedesktop.org/series/112214/)
- Alex: Keep a list of queues, instead of single queue per process.
- Christian: Use the queue manager instead of global ptrs,
           Don't keep the queue structure in amdgpu_ctx

V2:
 - Reformatted code, split the big patch into two

V3:
- Integration with doorbell manager

V4:
- Align the structure member names to the largest member's column
  (Luben)
- Added SPDX license (Luben)

V5:
- Do not add amdgpu.h in amdgpu_userqueue.h (Christian).
- Move struct amdgpu_userq_mgr into amdgpu_userqueue.h (Christian).

V6: Rebase
V9: Rebase
V10: Rebase + Alex's R-B

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

@@ -45,6 +45,7 @@
 #include "amdgpu_ras.h"
 #include "amdgpu_reset.h"
 #include "amd_pcie.h"
+#include "amdgpu_userqueue.h"
 
 void amdgpu_unregister_gpu_instance(struct amdgpu_device *adev)
 {
@@ -1378,6 +1379,10 @@ int amdgpu_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
 
 	amdgpu_ctx_mgr_init(&fpriv->ctx_mgr, adev);
 
+	r = amdgpu_userq_mgr_init(&fpriv->userq_mgr, adev);
+	if (r)
+		DRM_WARN("Can't setup usermode queues, use legacy workload submission only\n");
+
 	file_priv->driver_priv = fpriv;
 	goto out_suspend;
 
@@ -1447,6 +1452,7 @@ void amdgpu_driver_postclose_kms(struct drm_device *dev,
 
 	amdgpu_ctx_mgr_fini(&fpriv->ctx_mgr);
 	amdgpu_vm_fini(adev, &fpriv->vm);
+	amdgpu_userq_mgr_fini(&fpriv->userq_mgr);
 
 	if (pasid)
 		amdgpu_pasid_free_delayed(pd->tbo.base.resv, pasid);