[PATCH 11/16] drm/amdgpu: get absolute offset from doorbell index

[Shashank Sharma]

This patch adds a helper function which converts a doorbell's
relative index in a BO to an absolute doorbell offset in the
doorbell BAR.

Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Christian Koenig <christian.koenig at amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h  | 15 +++++++++++
 .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  | 26 +++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
index 10a9bb10e974..3481e9d83879 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
@@ -383,6 +383,21 @@ int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
  */
 int amdgpu_doorbell_create_kernel_doorbells(struct amdgpu_device *adev);
 
+/**
+ * amdgpu_doorbell_index_on_bar - Find doorbell's absolute offset in BAR
+ *
+ * @adev: amdgpu_device pointer
+ *
+ * @db_bo: doorbell object's bo
+ *
+ * @db_index: doorbell relative index in this doorbell object
+ *
+ * returns doorbell's absolute index in BAR
+ */
+uint32_t amdgpu_doorbell_index_on_bar(struct amdgpu_device *adev,
+				       struct amdgpu_bo *db_bo,
+				       uint32_t doorbell_index);
+
 #define RDOORBELL32(index) amdgpu_mm_rdoorbell(adev, (index))
 #define WDOORBELL32(index, v) amdgpu_mm_wdoorbell(adev, (index), (v))
 #define RDOORBELL64(index) amdgpu_mm_rdoorbell64(adev, (index))
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
index 81713b2c28e1..c263bae6b0c4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
@@ -130,6 +130,32 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device *adev, u32 index, u64 v)
 	}
 }
 
+/**
+ * amdgpu_doorbell_index_on_bar - Find doorbell's absolute offset in BAR
+ *
+ * @adev: amdgpu_device pointer
+ *
+ * @db_bo: doorbell object's bo
+ *
+ * @db_index: doorbell relative index in this doorbell object
+ *
+ * returns doorbell's absolute index in BAR
+ */
+uint32_t amdgpu_doorbell_index_on_bar(struct amdgpu_device *adev,
+				       struct amdgpu_bo *db_bo,
+				       uint32_t doorbell_index)
+{
+	int db_bo_offset;
+
+	db_bo_offset = amdgpu_bo_gpu_offset_no_check(db_bo);
+
+	/*
+	 * doorbell index granularity is maintained at 32 bit
+	 * but doorbell's size is 64-bit, so index * 2
+	 */
+	return db_bo_offset / sizeof(u32) + doorbell_index * 2;
+}
+
 /**
  * amdgpu_doorbell_free_page - Free a doorbell page
  *
-- 
2.40.0