[PATCH 07/16] drm/amdgpu: add helper to create doorbell pages

[Luben Tuikov]

On 2023-03-29 11:47, Shashank Sharma wrote:
> From: Shashank Sharma <contactshashanksharma at gmail.com>
> 
> This patch adds helper functions to create and free doorbell
> pages for kernel objects.
> 
> 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  | 41 ++++++++++++++++
>  .../gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c  | 49 +++++++++++++++++++
>  2 files changed, 90 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> index f9c3b77bf65d..6581b78fe438 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> @@ -27,6 +27,24 @@
>  /*
>   * GPU doorbell structures, functions & helpers
>   */
> +
> +/* Structure to hold doorbell pages from PCI doorbell BAR */
> +struct amdgpu_doorbell_obj {

In the comment you say "Structure to hold ...";
it is a C structure, but then in the name of a function we see "obj".
(Object is something which is defined like in memory, i.e. it exists, not
something which is only declared.)
This is just a declaration of a structure, not an object per se.
I'd call it "struct amdgpu_doorbell_struct" or just "struct amdgpu_doorbell".

Then in the definition, you can call it an object/objects, if you'd like,
like "struct amdgpu_doorbell *doorb_object[];" then you can say
"db = doorb_object[i]";

Regards,
Luben

> +	struct amdgpu_bo *bo;
> +	uint64_t gpu_addr;
> +	uint32_t *cpu_addr;
> +	uint32_t size;
> +
> +	/* First index in this object */
> +	uint32_t start;
> +
> +	/* Last index in this object */
> +	uint32_t end;
> +
> +	/* bitmap for dynamic doorbell allocation from this object */
> +	unsigned long *doorbell_bitmap;
> +};
> +
>  struct amdgpu_doorbell {
>  	/* doorbell mmio */
>  	resource_size_t		base;
> @@ -328,6 +346,29 @@ int amdgpu_device_doorbell_init(struct amdgpu_device *adev);
>   */
>  void amdgpu_device_doorbell_fini(struct amdgpu_device *adev);
>  
> +/**
> + * amdgpu_doorbell_free_page - Free a doorbell page
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * @db_age: previously allocated doobell page details
> + *
> + */
> +void amdgpu_doorbell_free_page(struct amdgpu_device *adev,
> +				struct amdgpu_doorbell_obj *db_obj);
> +
> +/**
> + * amdgpu_doorbell_alloc_page - create a page from doorbell pool
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * @db_age: doobell page structure to fill details with
> + *
> + * returns 0 on success, else error number
> + */
> +int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
> +				struct amdgpu_doorbell_obj *db_obj);
> +
>  #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 1aea92363fd3..8be15b82b545 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell_mgr.c
> @@ -111,6 +111,55 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device *adev, u32 index, u64 v)
>  	}
>  }
>  
> +/**
> + * amdgpu_doorbell_free_page - Free a doorbell page
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * @db_age: previously allocated doobell page details
> + *
> + */
> +void amdgpu_doorbell_free_page(struct amdgpu_device *adev,
> +					struct amdgpu_doorbell_obj *db_obj)
> +{
> +	amdgpu_bo_free_kernel(&db_obj->bo,
> +			      &db_obj->gpu_addr,
> +			      (void **)&db_obj->cpu_addr);
> +
> +}
> +
> +/**
> + * amdgpu_doorbell_alloc_page - create a page from doorbell pool
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * @db_age: doobell page structure to fill details with
> + *
> + * returns 0 on success, else error number
> + */
> +int amdgpu_doorbell_alloc_page(struct amdgpu_device *adev,
> +				struct amdgpu_doorbell_obj *db_obj)
> +{
> +	int r;
> +
> +	db_obj->size = ALIGN(db_obj->size, PAGE_SIZE);
> +
> +	r = amdgpu_bo_create_kernel(adev,
> +				    db_obj->size,
> +				    PAGE_SIZE,
> +				    AMDGPU_GEM_DOMAIN_DOORBELL,
> +				    &db_obj->bo,
> +				    &db_obj->gpu_addr,
> +				    (void **)&db_obj->cpu_addr);
> +
> +	if (r) {
> +		DRM_ERROR("Failed to create doorbell BO, err=%d\n", r);
> +		return r;
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * GPU doorbell aperture helpers function.
>   */