[PATCH v2 10/25] iommu/exynos: Implement an IDENTITY domain

[Marek Szyprowski]

On 16.05.2023 02:00, Jason Gunthorpe wrote:
> What exynos calls exynos_iommu_detach_device 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 at nvidia.com>

Acked-by: Marek Szyprowski

> ---
>   drivers/iommu/exynos-iommu.c | 66 +++++++++++++++++-------------------
>   1 file changed, 32 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index c275fe71c4db32..5e12b85dfe8705 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -24,6 +24,7 @@
>   
>   typedef u32 sysmmu_iova_t;
>   typedef u32 sysmmu_pte_t;
> +static struct iommu_domain exynos_identity_domain;
>   
>   /* We do not consider super section mapping (16MB) */
>   #define SECT_ORDER 20
> @@ -829,7 +830,7 @@ static int __maybe_unused exynos_sysmmu_suspend(struct device *dev)
>   		struct exynos_iommu_owner *owner = dev_iommu_priv_get(master);
>   
>   		mutex_lock(&owner->rpm_lock);
> -		if (data->domain) {
> +		if (&data->domain->domain != &exynos_identity_domain) {
>   			dev_dbg(data->sysmmu, "saving state\n");
>   			__sysmmu_disable(data);
>   		}
> @@ -847,7 +848,7 @@ static int __maybe_unused exynos_sysmmu_resume(struct device *dev)
>   		struct exynos_iommu_owner *owner = dev_iommu_priv_get(master);
>   
>   		mutex_lock(&owner->rpm_lock);
> -		if (data->domain) {
> +		if (&data->domain->domain != &exynos_identity_domain) {
>   			dev_dbg(data->sysmmu, "restoring state\n");
>   			__sysmmu_enable(data);
>   		}
> @@ -980,17 +981,20 @@ static void exynos_iommu_domain_free(struct iommu_domain *iommu_domain)
>   	kfree(domain);
>   }
>   
> -static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
> -				    struct device *dev)
> +static int exynos_iommu_identity_attach(struct iommu_domain *identity_domain,
> +					struct device *dev)
>   {
> -	struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
>   	struct exynos_iommu_owner *owner = dev_iommu_priv_get(dev);
> -	phys_addr_t pagetable = virt_to_phys(domain->pgtable);
> +	struct exynos_iommu_domain *domain;
> +	phys_addr_t pagetable;
>   	struct sysmmu_drvdata *data, *next;
>   	unsigned long flags;
>   
> -	if (!has_sysmmu(dev) || owner->domain != iommu_domain)
> -		return;
> +	if (owner->domain == identity_domain)
> +		return 0;
> +
> +	domain = to_exynos_domain(owner->domain);
> +	pagetable = virt_to_phys(domain->pgtable);
>   
>   	mutex_lock(&owner->rpm_lock);
>   
> @@ -1009,15 +1013,25 @@ static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
>   		list_del_init(&data->domain_node);
>   		spin_unlock(&data->lock);
>   	}
> -	owner->domain = NULL;
> +	owner->domain = identity_domain;
>   	spin_unlock_irqrestore(&domain->lock, flags);
>   
>   	mutex_unlock(&owner->rpm_lock);
>   
> -	dev_dbg(dev, "%s: Detached IOMMU with pgtable %pa\n", __func__,
> -		&pagetable);
> +	dev_dbg(dev, "%s: Restored IOMMU to IDENTITY from pgtable %pa\n",
> +		__func__, &pagetable);
> +	return 0;
>   }
>   
> +static struct iommu_domain_ops exynos_identity_ops = {
> +	.attach_dev = exynos_iommu_identity_attach,
> +};
> +
> +static struct iommu_domain exynos_identity_domain = {
> +	.type = IOMMU_DOMAIN_IDENTITY,
> +	.ops = &exynos_identity_ops,
> +};
> +
>   static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
>   				   struct device *dev)
>   {
> @@ -1026,12 +1040,11 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
>   	struct sysmmu_drvdata *data;
>   	phys_addr_t pagetable = virt_to_phys(domain->pgtable);
>   	unsigned long flags;
> +	int err;
>   
> -	if (!has_sysmmu(dev))
> -		return -ENODEV;
> -
> -	if (owner->domain)
> -		exynos_iommu_detach_device(owner->domain, dev);
> +	err = exynos_iommu_identity_attach(&exynos_identity_domain, dev);
> +	if (err)
> +		return err;
>   
>   	mutex_lock(&owner->rpm_lock);
>   
> @@ -1407,26 +1420,12 @@ static struct iommu_device *exynos_iommu_probe_device(struct device *dev)
>   	return &data->iommu;
>   }
>   
> -static void exynos_iommu_set_platform_dma(struct device *dev)
> -{
> -	struct exynos_iommu_owner *owner = dev_iommu_priv_get(dev);
> -
> -	if (owner->domain) {
> -		struct iommu_group *group = iommu_group_get(dev);
> -
> -		if (group) {
> -			exynos_iommu_detach_device(owner->domain, dev);
> -			iommu_group_put(group);
> -		}
> -	}
> -}
> -
>   static void exynos_iommu_release_device(struct device *dev)
>   {
>   	struct exynos_iommu_owner *owner = dev_iommu_priv_get(dev);
>   	struct sysmmu_drvdata *data;
>   
> -	exynos_iommu_set_platform_dma(dev);
> +	WARN_ON(exynos_iommu_identity_attach(&exynos_identity_domain, dev));
>   
>   	list_for_each_entry(data, &owner->controllers, owner_node)
>   		device_link_del(data->link);
> @@ -1457,6 +1456,7 @@ static int exynos_iommu_of_xlate(struct device *dev,
>   
>   		INIT_LIST_HEAD(&owner->controllers);
>   		mutex_init(&owner->rpm_lock);
> +		owner->domain = &exynos_identity_domain;
>   		dev_iommu_priv_set(dev, owner);
>   	}
>   
> @@ -1471,11 +1471,9 @@ static int exynos_iommu_of_xlate(struct device *dev,
>   }
>   
>   static const struct iommu_ops exynos_iommu_ops = {
> +	.identity_domain = &exynos_identity_domain,
>   	.domain_alloc = exynos_iommu_domain_alloc,
>   	.device_group = generic_device_group,
> -#ifdef CONFIG_ARM
> -	.set_platform_dma_ops = exynos_iommu_set_platform_dma,
> -#endif
>   	.probe_device = exynos_iommu_probe_device,
>   	.release_device = exynos_iommu_release_device,
>   	.pgsize_bitmap = SECT_SIZE | LPAGE_SIZE | SPAGE_SIZE,

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland