Re: [PATCH v6 11/25] iommu/tegra-smmu: Implement an IDENTITY domain

[Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>]

On 2023/8/3 8:07, Jason Gunthorpe wrote:
> What tegra-smmu does during tegra_smmu_set_platform_dma() is actually
> putting the iommu into identity mode.
>
> Move to the new core support for ARM_DMA_USE_IOMMU by defining
> ops->identity_domain.
>
> Signed-off-by: Jason Gunthorpe<jgg@xxxxxxxxxx>
> ---
>   drivers/iommu/tegra-smmu.c | 37 ++++++++++++++++++++++++++++++++-----
>   1 file changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 1cbf063ccf147a..f63f1d4f0bd10f 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -511,23 +511,39 @@ static int tegra_smmu_attach_dev(struct iommu_domain *domain,
>   	return err;
>   }
>   
> -static void tegra_smmu_set_platform_dma(struct device *dev)
> +static int tegra_smmu_identity_attach(struct iommu_domain *identity_domain,
> +				      struct device *dev)
>   {
>   	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
>   	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> -	struct tegra_smmu_as *as = to_smmu_as(domain);
> -	struct tegra_smmu *smmu = as->smmu;
> +	struct tegra_smmu_as *as;
> +	struct tegra_smmu *smmu;
>   	unsigned int index;
>   
>   	if (!fwspec)
> -		return;
> +		return -ENODEV;
>   
> +	if (domain == identity_domain || !domain)
> +		return 0;
> +
> +	as = to_smmu_as(domain);
> +	smmu = as->smmu;
>   	for (index = 0; index < fwspec->num_ids; index++) {
>   		tegra_smmu_disable(smmu, fwspec->ids[index], as->id);
>   		tegra_smmu_as_unprepare(smmu, as);
>   	}
> +	return 0;
>   }
>   
> +static struct iommu_domain_ops tegra_smmu_identity_ops = {
> +	.attach_dev = tegra_smmu_identity_attach,
> +};
> +
> +static struct iommu_domain tegra_smmu_identity_domain = {
> +	.type = IOMMU_DOMAIN_IDENTITY,
> +	.ops = &tegra_smmu_identity_ops,
> +};
> +
>   static void tegra_smmu_set_pde(struct tegra_smmu_as *as, unsigned long iova,
>   			       u32 value)
>   {
> @@ -962,11 +978,22 @@ static int tegra_smmu_of_xlate(struct device *dev,
>   	return iommu_fwspec_add_ids(dev, &id, 1);
>   }
>   
> +static int tegra_smmu_def_domain_type(struct device *dev)
> +{
> +	/*
> +	 * FIXME: For now we want to run all translation in IDENTITY mode, due
> +	 * to some device quirks. Better would be to just quirk the troubled
> +	 * devices.
> +	 */
> +	return IOMMU_DOMAIN_IDENTITY;
> +}

Hope somebody can fix this later on.

Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Best regards,
baolu