[PATCH v6 07/25] iommu/mtk_iommu_v1: Implement an IDENTITY domain

[Baolu Lu]

On 2023/8/3 8:07, Jason Gunthorpe wrote:
> What mtk does during mtk_iommu_v1_set_platform_dma() is actually putting
> the iommu into identity mode. Make this available as a proper IDENTITY
> domain.
> 
> The mtk_iommu_v1_def_domain_type() from
> commit 8bbe13f52cb7 ("iommu/mediatek-v1: Add def_domain_type") explains
> this was needed to allow probe_finalize() to be called, but now the
> IDENTITY domain will do the same job so change the returned
> def_domain_type.
> 
> mkt_v1 is the only driver that returns IOMMU_DOMAIN_UNMANAGED from
> def_domain_type().  This allows the next patch to enforce an IDENTITY
> domain policy for this driver.

This code seems to be not working properly.

  * @def_domain_type: device default domain type, return value:
  *              - IOMMU_DOMAIN_IDENTITY: must use an identity domain
  *              - IOMMU_DOMAIN_DMA: must use a dma domain
  *              - 0: use the default setting

The core code is not ready to accept any other return value.

> 
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> ---
>   drivers/iommu/mtk_iommu_v1.c | 21 +++++++++++++++++++--
>   1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
> index 8a0a5e5d049f4a..cc3e7d53d33ad9 100644
> --- a/drivers/iommu/mtk_iommu_v1.c
> +++ b/drivers/iommu/mtk_iommu_v1.c
> @@ -319,11 +319,27 @@ static int mtk_iommu_v1_attach_device(struct iommu_domain *domain, struct device
>   	return 0;
>   }
>   
> -static void mtk_iommu_v1_set_platform_dma(struct device *dev)
> +static int mtk_iommu_v1_identity_attach(struct iommu_domain *identity_domain,
> +					struct device *dev)
>   {
>   	struct mtk_iommu_v1_data *data = dev_iommu_priv_get(dev);
>   
>   	mtk_iommu_v1_config(data, dev, false);
> +	return 0;
> +}
> +
> +static struct iommu_domain_ops mtk_iommu_v1_identity_ops = {
> +	.attach_dev = mtk_iommu_v1_identity_attach,
> +};
> +
> +static struct iommu_domain mtk_iommu_v1_identity_domain = {
> +	.type = IOMMU_DOMAIN_IDENTITY,
> +	.ops = &mtk_iommu_v1_identity_ops,
> +};
> +
> +static void mtk_iommu_v1_set_platform_dma(struct device *dev)
> +{
> +	mtk_iommu_v1_identity_attach(&mtk_iommu_v1_identity_domain, dev);

This callback seems to be a dead code now.

>   }
>   
>   static int mtk_iommu_v1_map(struct iommu_domain *domain, unsigned long iova,
> @@ -443,7 +459,7 @@ static int mtk_iommu_v1_create_mapping(struct device *dev, struct of_phandle_arg
>   
>   static int mtk_iommu_v1_def_domain_type(struct device *dev)
>   {
> -	return IOMMU_DOMAIN_UNMANAGED;
> +	return IOMMU_DOMAIN_IDENTITY;

def_domain_type can't be used for this purpose. But this seems to be a
temporary code, as it will be removed in patch 09/25.

>   }
>   
>   static struct iommu_device *mtk_iommu_v1_probe_device(struct device *dev)
> @@ -578,6 +594,7 @@ static int mtk_iommu_v1_hw_init(const struct mtk_iommu_v1_data *data)
>   }
>   
>   static const struct iommu_ops mtk_iommu_v1_ops = {
> +	.identity_domain = &mtk_iommu_v1_identity_domain,
>   	.domain_alloc	= mtk_iommu_v1_domain_alloc,
>   	.probe_device	= mtk_iommu_v1_probe_device,
>   	.probe_finalize = mtk_iommu_v1_probe_finalize,

Best regards,
baolu