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Subject: Re: [PATCH v4 09/13] iommu/rockchip: Use IOMMU device for dma mapping
 operations
To:     Jeffy Chen <jeffy.chen@rock-chips.com>,
        linux-kernel@vger.kernel.org
Cc:     jcliang@chromium.org, xxm@rock-chips.com, tfiga@chromium.org,
        Heiko Stuebner <heiko@sntech.de>,
        linux-rockchip@lists.infradead.org,
        iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>,
        linux-arm-kernel@lists.infradead.org
References: <20180118115251.5542-1-jeffy.chen@rock-chips.com>
 <20180118115251.5542-10-jeffy.chen@rock-chips.com>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <0b680e53-e62b-12cb-38b6-32f073250cf0@arm.com>
Date:   Thu, 18 Jan 2018 12:35:25 +0000
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On 18/01/18 11:52, Jeffy Chen wrote:
> Use the first registered IOMMU device for dma mapping operations, and
> drop the domain platform device.
> 
> This is similar to exynos iommu driver.

I'd been meaning to look into this myself for the sake of removing the 
arch_setup_dma_ops() hack, so I'm glad to see it done :)

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> Reviewed-by: Tomasz Figa <tfiga@chromium.org>
> ---
> 
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> 
>   drivers/iommu/rockchip-iommu.c | 85 ++++++++++++------------------------------
>   1 file changed, 24 insertions(+), 61 deletions(-)
> 
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index 9b85a3050449..bdb7c5de6fc2 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -77,7 +77,6 @@
>   
>   struct rk_iommu_domain {
>   	struct list_head iommus;
> -	struct platform_device *pdev;
>   	u32 *dt; /* page directory table */
>   	dma_addr_t dt_dma;
>   	spinlock_t iommus_lock; /* lock for iommus list */
> @@ -98,12 +97,14 @@ struct rk_iommu {
>   	struct iommu_domain *domain; /* domain to which iommu is attached */
>   };
>   
> +static struct device *dma_dev;
> +
>   static inline void rk_table_flush(struct rk_iommu_domain *dom, dma_addr_t dma,
>   				  unsigned int count)
>   {
>   	size_t size = count * sizeof(u32); /* count of u32 entry */
>   
> -	dma_sync_single_for_device(&dom->pdev->dev, dma, size, DMA_TO_DEVICE);
> +	dma_sync_single_for_device(dma_dev, dma, size, DMA_TO_DEVICE);
>   }
>   
>   static struct rk_iommu_domain *to_rk_domain(struct iommu_domain *dom)
> @@ -690,7 +691,6 @@ static void rk_iommu_zap_iova_first_last(struct rk_iommu_domain *rk_domain,
>   static u32 *rk_dte_get_page_table(struct rk_iommu_domain *rk_domain,
>   				  dma_addr_t iova)
>   {
> -	struct device *dev = &rk_domain->pdev->dev;
>   	u32 *page_table, *dte_addr;
>   	u32 dte_index, dte;
>   	phys_addr_t pt_phys;
> @@ -708,9 +708,9 @@ static u32 *rk_dte_get_page_table(struct rk_iommu_domain *rk_domain,
>   	if (!page_table)
>   		return ERR_PTR(-ENOMEM);
>   
> -	pt_dma = dma_map_single(dev, page_table, SPAGE_SIZE, DMA_TO_DEVICE);
> -	if (dma_mapping_error(dev, pt_dma)) {
> -		dev_err(dev, "DMA mapping error while allocating page table\n");
> +	pt_dma = dma_map_single(dma_dev, page_table, SPAGE_SIZE, DMA_TO_DEVICE);
> +	if (dma_mapping_error(dma_dev, pt_dma)) {
> +		dev_err(dma_dev, "DMA mapping error while allocating page table\n");
>   		free_page((unsigned long)page_table);
>   		return ERR_PTR(-ENOMEM);
>   	}
> @@ -982,29 +982,20 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
>   static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
>   {
>   	struct rk_iommu_domain *rk_domain;
> -	struct platform_device *pdev;
> -	struct device *iommu_dev;
>   
>   	if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
>   		return NULL;
>   
> -	/* Register a pdev per domain, so DMA API can base on this *dev
> -	 * even some virtual master doesn't have an iommu slave
> -	 */
> -	pdev = platform_device_register_simple("rk_iommu_domain",
> -					       PLATFORM_DEVID_AUTO, NULL, 0);
> -	if (IS_ERR(pdev))
> +	if (!dma_dev)
>   		return NULL;
>   
> -	rk_domain = devm_kzalloc(&pdev->dev, sizeof(*rk_domain), GFP_KERNEL);
> +	rk_domain = devm_kzalloc(dma_dev, sizeof(*rk_domain), GFP_KERNEL);
>   	if (!rk_domain)
> -		goto err_unreg_pdev;
> -
> -	rk_domain->pdev = pdev;
> +		return NULL;
>   
>   	if (type == IOMMU_DOMAIN_DMA &&
>   	    iommu_get_dma_cookie(&rk_domain->domain))
> -		goto err_unreg_pdev;
> +		return NULL;
>   
>   	/*
>   	 * rk32xx iommus use a 2 level pagetable.
> @@ -1015,11 +1006,10 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
>   	if (!rk_domain->dt)
>   		goto err_put_cookie;
>   
> -	iommu_dev = &pdev->dev;
> -	rk_domain->dt_dma = dma_map_single(iommu_dev, rk_domain->dt,
> +	rk_domain->dt_dma = dma_map_single(dma_dev, rk_domain->dt,
>   					   SPAGE_SIZE, DMA_TO_DEVICE);
> -	if (dma_mapping_error(iommu_dev, rk_domain->dt_dma)) {
> -		dev_err(iommu_dev, "DMA map error for DT\n");
> +	if (dma_mapping_error(dma_dev, rk_domain->dt_dma)) {
> +		dev_err(dma_dev, "DMA map error for DT\n");
>   		goto err_free_dt;
>   	}
>   
> @@ -1040,8 +1030,6 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
>   err_put_cookie:
>   	if (type == IOMMU_DOMAIN_DMA)
>   		iommu_put_dma_cookie(&rk_domain->domain);
> -err_unreg_pdev:
> -	platform_device_unregister(pdev);
>   
>   	return NULL;
>   }
> @@ -1058,20 +1046,18 @@ static void rk_iommu_domain_free(struct iommu_domain *domain)
>   		if (rk_dte_is_pt_valid(dte)) {
>   			phys_addr_t pt_phys = rk_dte_pt_address(dte);
>   			u32 *page_table = phys_to_virt(pt_phys);
> -			dma_unmap_single(&rk_domain->pdev->dev, pt_phys,
> +			dma_unmap_single(dma_dev, pt_phys,
>   					 SPAGE_SIZE, DMA_TO_DEVICE);
>   			free_page((unsigned long)page_table);
>   		}
>   	}
>   
> -	dma_unmap_single(&rk_domain->pdev->dev, rk_domain->dt_dma,
> +	dma_unmap_single(dma_dev, rk_domain->dt_dma,
>   			 SPAGE_SIZE, DMA_TO_DEVICE);
>   	free_page((unsigned long)rk_domain->dt);
>   
>   	if (domain->type == IOMMU_DOMAIN_DMA)
>   		iommu_put_dma_cookie(&rk_domain->domain);
> -
> -	platform_device_unregister(rk_domain->pdev);
>   }
>   
>   static bool rk_iommu_is_dev_iommu_master(struct device *dev)
> @@ -1194,30 +1180,6 @@ static const struct iommu_ops rk_iommu_ops = {
>   	.pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP,
>   };
>   
> -static int rk_iommu_domain_probe(struct platform_device *pdev)
> -{
> -	struct device *dev = &pdev->dev;
> -
> -	dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms), GFP_KERNEL);
> -	if (!dev->dma_parms)
> -		return -ENOMEM;
> -
> -	/* Set dma_ops for dev, otherwise it would be dummy_dma_ops */
> -	arch_setup_dma_ops(dev, 0, DMA_BIT_MASK(32), NULL, false);
> -
> -	dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
> -	dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
> -
> -	return 0;
> -}
> -
> -static struct platform_driver rk_iommu_domain_driver = {
> -	.probe = rk_iommu_domain_probe,
> -	.driver = {
> -		   .name = "rk_iommu_domain",
> -	},
> -};
> -
>   static int rk_iommu_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> @@ -1278,6 +1240,14 @@ static int rk_iommu_probe(struct platform_device *pdev)
>   	if (err)
>   		goto err_remove_sysfs;
>   
> +	/*
> +	 * Use the first registered IOMMU device for domain to use with DMA
> +	 * API, since a domain might not physically correspond to a single
> +	 * IOMMU device..
> +	 */
> +	if (!dma_dev)
> +		dma_dev = &pdev->dev;
> +
>   	return 0;
>   err_remove_sysfs:
>   	iommu_device_sysfs_remove(&iommu->iommu);
> @@ -1316,14 +1286,7 @@ static int __init rk_iommu_init(void)
>   	if (ret)
>   		return ret;
>   
> -	ret = platform_driver_register(&rk_iommu_domain_driver);
> -	if (ret)
> -		return ret;
> -
> -	ret = platform_driver_register(&rk_iommu_driver);
> -	if (ret)
> -		platform_driver_unregister(&rk_iommu_domain_driver);
> -	return ret;
> +	return platform_driver_register(&rk_iommu_driver);
>   }
>   subsys_initcall(rk_iommu_init);
>   
>