Re: [PATCH v5 06/10] iommu/mediatek: Add sub_comm id in translation fault

[Yong Wu]

On Mon, 2020-06-29 at 15:13 +0800, Chao Hao wrote:
> The max larb number that a iommu HW support is 8(larb0~larb7 in the below
> diagram).
> If the larb's number is over 8, we use a sub_common for merging
> several larbs into one larb. At this case, we will extend larb_id:
> bit[11:9] means common-id;
> bit[8:7] means subcommon-id;
> From these two variables, we could get the real larb number when
> translation fault happen.
> The diagram is as below:
> 		 EMI
> 		  |
> 		IOMMU
> 		  |
>            -----------------
> 	   |               |
> 	common1   	common0
> 	   |		   |
> 	   -----------------
> 		  |
>              smi common
> 		  |
>   ------------------------------------
>   |       |       |       |     |    |
>  3'd0    3'd1    3'd2    3'd3  ...  3'd7   <-common_id(max is 8)
>   |       |       |       |     |    |
> Larb0   Larb1     |     Larb3  ... Larb7
> 		  |
> 	    smi sub common
> 		  |
>      --------------------------
>      |        |       |       |
>     2'd0     2'd1    2'd2    2'd3   <-sub_common_id(max is 4)
>      |        |       |       |
>    Larb8    Larb9   Larb10  Larb11
> 
> In this patch we extend larb_remap[] to larb_remap[8][4] for this.
> larb_remap[x][y]: x means common-id above, y means subcommon_id above.
> 
> We can also distinguish if the M4U HW has sub_common by HAS_SUB_COMM
> macro.
> 
> Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx>
> Signed-off-by: Chao Hao <chao.hao@xxxxxxxxxxxx>
> Reviewed-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> ---
>  drivers/iommu/mtk_iommu.c  | 20 +++++++++++++-------
>  drivers/iommu/mtk_iommu.h  |  3 ++-
>  include/soc/mediatek/smi.h |  2 ++
>  3 files changed, 17 insertions(+), 8 deletions(-)

[snip]

> @@ -48,7 +49,7 @@ struct mtk_iommu_plat_data {
>  	enum mtk_iommu_plat m4u_plat;
>  	u32                 flags;
>  	u32                 inv_sel_reg;
> -	unsigned char       larbid_remap[MTK_LARB_NR_MAX];
> +	unsigned char       larbid_remap[MTK_LARB_COM_MAX][MTK_LARB_SUBCOM_MAX];
>  };
>  
>  struct mtk_iommu_domain;
> diff --git a/include/soc/mediatek/smi.h b/include/soc/mediatek/smi.h
> index 5a34b87d89e3..fa65a55468e2 100644
> --- a/include/soc/mediatek/smi.h
> +++ b/include/soc/mediatek/smi.h
> @@ -12,6 +12,8 @@
>  #ifdef CONFIG_MTK_SMI
>  
>  #define MTK_LARB_NR_MAX		16
> +#define MTK_LARB_COM_MAX	8
> +#define MTK_LARB_SUBCOM_MAX	4

Both are only used in mtk_iommu.h, and I don't think smi has plan to use
them. thus we could move them into mtk_iommu.h

>  
>  #define MTK_SMI_MMU_EN(port)	BIT(port)
>