drm/amdgpu: create kernel doorbell pages

This patch:
- creates a doorbell page for graphics driver usages.
- adds a few new varlables in adev->doorbell structure to
  keep track of kernel's doorbell-bo.
- removes the adev->doorbell.ptr variable, replaces it with
  kernel-doorbell-bo's cpu address.

V2: - Create doorbell BO directly, no wrappe functions (Alex)
    - no additional doorbell structure (Alex, Christian)
    - Use doorbell_cpu_ptr, remove ioremap (Christian, Alex)
    - Allocate one extra page of doorbells for MES (Alex)

V4: Move MES doorbell base init into MES related patch (Christian)

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@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_doorbell.h

@@ -31,10 +31,15 @@ struct amdgpu_doorbell {
 	/* doorbell mmio */
 	resource_size_t		base;
 	resource_size_t		size;
-	u32 __iomem		*ptr;
 
 	/* Number of doorbells reserved for amdgpu kernel driver */
 	u32 num_kernel_doorbells;
+
+	/* Kernel doorbells */
+	struct amdgpu_bo *kernel_doorbells;
+
+	/* For CPU access of doorbells */
+	uint32_t *cpu_addr;
 };
 
 /* Reserved doorbells for amdgpu (including multimedia).
@@ -350,6 +355,7 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device *adev, u32 index, u64 v);
  */
 int amdgpu_doorbell_init(struct amdgpu_device *adev);
 void amdgpu_doorbell_fini(struct amdgpu_device *adev);
+int amdgpu_doorbell_create_kernel_doorbells(struct amdgpu_device *adev);
 
 #define RDOORBELL32(index) amdgpu_mm_rdoorbell(adev, (index))
 #define WDOORBELL32(index, v) amdgpu_mm_wdoorbell(adev, (index), (v))

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

@@ -39,7 +39,7 @@ u32 amdgpu_mm_rdoorbell(struct amdgpu_device *adev, u32 index)
 		return 0;
 
 	if (index < adev->doorbell.num_kernel_doorbells)
-		return readl(adev->doorbell.ptr + index);
+		return readl(adev->doorbell.cpu_addr + index);
 
 	DRM_ERROR("reading beyond doorbell aperture: 0x%08x!\n", index);
 	return 0;
@@ -61,7 +61,7 @@ void amdgpu_mm_wdoorbell(struct amdgpu_device *adev, u32 index, u32 v)
 		return;
 
 	if (index < adev->doorbell.num_kernel_doorbells)
-		writel(v, adev->doorbell.ptr + index);
+		writel(v, adev->doorbell.cpu_addr + index);
 	else
 		DRM_ERROR("writing beyond doorbell aperture: 0x%08x!\n", index);
 }
@@ -81,7 +81,7 @@ u64 amdgpu_mm_rdoorbell64(struct amdgpu_device *adev, u32 index)
 		return 0;
 
 	if (index < adev->doorbell.num_kernel_doorbells)
-		return atomic64_read((atomic64_t *)(adev->doorbell.ptr + index));
+		return atomic64_read((atomic64_t *)(adev->doorbell.cpu_addr + index));
 
 	DRM_ERROR("reading beyond doorbell aperture: 0x%08x!\n", index);
 	return 0;
@@ -103,11 +103,43 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device *adev, u32 index, u64 v)
 		return;
 
 	if (index < adev->doorbell.num_kernel_doorbells)
-		atomic64_set((atomic64_t *)(adev->doorbell.ptr + index), v);
+		atomic64_set((atomic64_t *)(adev->doorbell.cpu_addr + index), v);
 	else
 		DRM_ERROR("writing beyond doorbell aperture: 0x%08x!\n", index);
 }
 
+/**
+ * amdgpu_doorbell_create_kernel_doorbells - Create kernel doorbells for graphics
+ *
+ * @adev: amdgpu_device pointer
+ *
+ * Creates doorbells for graphics driver usages.
+ * returns 0 on success, error otherwise.
+ */
+int amdgpu_doorbell_create_kernel_doorbells(struct amdgpu_device *adev)
+{
+	int r;
+	int size;
+
+	/* Reserve first num_kernel_doorbells (page-aligned) for kernel ops */
+	size = ALIGN(adev->doorbell.num_kernel_doorbells * sizeof(u32), PAGE_SIZE);
+
+	r = amdgpu_bo_create_kernel(adev,
+				    size,
+				    PAGE_SIZE,
+				    AMDGPU_GEM_DOMAIN_DOORBELL,
+				    &adev->doorbell.kernel_doorbells,
+				    NULL,
+				    (void **)&adev->doorbell.cpu_addr);
+	if (r) {
+		DRM_ERROR("Failed to allocate kernel doorbells, err=%d\n", r);
+		return r;
+	}
+
+	adev->doorbell.num_kernel_doorbells = size / sizeof(u32);
+	return 0;
+}
+
 /*
  * GPU doorbell aperture helpers function.
  */
@@ -127,7 +159,6 @@ int amdgpu_doorbell_init(struct amdgpu_device *adev)
 		adev->doorbell.base = 0;
 		adev->doorbell.size = 0;
 		adev->doorbell.num_kernel_doorbells = 0;
-		adev->doorbell.ptr = NULL;
 		return 0;
 	}
 
@@ -156,12 +187,6 @@ int amdgpu_doorbell_init(struct amdgpu_device *adev)
 	if (adev->asic_type >= CHIP_VEGA10)
 		adev->doorbell.num_kernel_doorbells += 0x400;
 
-	adev->doorbell.ptr = ioremap(adev->doorbell.base,
-				     adev->doorbell.num_kernel_doorbells *
-				     sizeof(u32));
-	if (adev->doorbell.ptr == NULL)
-		return -ENOMEM;
-
 	return 0;
 }
 
@@ -174,6 +199,7 @@ int amdgpu_doorbell_init(struct amdgpu_device *adev)
  */
 void amdgpu_doorbell_fini(struct amdgpu_device *adev)
 {
-	iounmap(adev->doorbell.ptr);
+	amdgpu_bo_free_kernel(&adev->doorbell.kernel_doorbells,
-	adev->doorbell.ptr = NULL;
+			      NULL,
+			      (void **)&adev->doorbell.cpu_addr);
 }

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

@@ -1945,6 +1945,13 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
 		return r;
 	}
 
+	/* Create a boorbell page for kernel usages */
+	r = amdgpu_doorbell_create_kernel_doorbells(adev);
+	if (r) {
+		DRM_ERROR("Failed to initialize kernel doorbells.\n");
+		return r;
+	}
+
 	/* Initialize preemptible memory pool */
 	r = amdgpu_preempt_mgr_init(adev);
 	if (r) {