Re: [PATCH v3 2/9] iommu/of: Consolidate device creation workarounds

[Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>]

On Tue, Jun 28, 2016 at 04:48:21PM +0100, Robin Murphy wrote:
> So far, all the users of the generic of_xlate configuration mechanism
> are resorting to explicit platform device creation to ensure the IOMMU
> device is ready before anything tries to refer to it. As I'm about to
> convert two more drivers that will need exactly the same thing, let's
> nip that proliferation in the bud and move it to a single place.
> 
> A neat solution is to make of_get_iommu_ops() ensure an IOMMU device is
> instantiated before giving out its associated ops, since it's a fairly
> safe assumption that the ops aren't going to be much use if the IOMMU
> can't or won't exist to back them up.
> 
> CC: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> CC: Yong Wu <yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
> ---

Marek, Yong, can I have your acks on this please? It's a fairly
straightforward change, but the subsequent arm-smmu patches rely on it.

Thanks,

Will

>  drivers/iommu/exynos-iommu.c | 20 +++++++-------------
>  drivers/iommu/mtk_iommu.c    |  8 +-------
>  drivers/iommu/of_iommu.c     |  6 +++++-
>  3 files changed, 13 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 5ecc86cb74c8..97380ee56d71 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -665,6 +665,13 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
>  
>  	pm_runtime_enable(dev);
>  
> +	/*
> +	 * use the first registered sysmmu device for performing
> +	 * dma mapping operations on iommu page tables (cpu cache flush)
> +	 */
> +	if (!dma_dev)
> +		dma_dev = dev;
> +
>  	return 0;
>  }
>  
> @@ -1341,22 +1348,9 @@ err_reg_driver:
>  
>  static int __init exynos_iommu_of_setup(struct device_node *np)
>  {
> -	struct platform_device *pdev;
> -
>  	if (!init_done)
>  		exynos_iommu_init();
>  
> -	pdev = of_platform_device_create(np, NULL, platform_bus_type.dev_root);
> -	if (IS_ERR(pdev))
> -		return PTR_ERR(pdev);
> -
> -	/*
> -	 * use the first registered sysmmu device for performing
> -	 * dma mapping operations on iommu page tables (cpu cache flush)
> -	 */
> -	if (!dma_dev)
> -		dma_dev = &pdev->dev;
> -
>  	of_iommu_set_ops(np, &exynos_iommu_ops);
>  	return 0;
>  }
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index c3043d8754e3..f7ae87abea99 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -724,14 +724,8 @@ static struct platform_driver mtk_iommu_driver = {
>  
>  static int mtk_iommu_init_fn(struct device_node *np)
>  {
> -	int ret;
> -	struct platform_device *pdev;
> +	int ret = platform_driver_register(&mtk_iommu_driver);
>  
> -	pdev = of_platform_device_create(np, NULL, platform_bus_type.dev_root);
> -	if (!pdev)
> -		return -ENOMEM;
> -
> -	ret = platform_driver_register(&mtk_iommu_driver);
>  	if (ret) {
>  		pr_err("%s: Failed to register driver\n", __func__);
>  		return ret;
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index af499aea0a1a..7e6369cffc95 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -22,6 +22,7 @@
>  #include <linux/limits.h>
>  #include <linux/of.h>
>  #include <linux/of_iommu.h>
> +#include <linux/of_platform.h>
>  #include <linux/slab.h>
>  
>  static const struct of_device_id __iommu_of_table_sentinel
> @@ -127,7 +128,10 @@ const struct iommu_ops *of_iommu_get_ops(struct device_node *np)
>  	spin_lock(&of_iommu_lock);
>  	list_for_each_entry(node, &of_iommu_list, list)
>  		if (node->np == np) {
> -			ops = node->ops;
> +			if (of_node_check_flag(np, OF_POPULATED) ||
> +			    of_platform_device_create(np, NULL,
> +					    platform_bus_type.dev_root))
> +				ops = node->ops;
>  			break;
>  		}
>  	spin_unlock(&of_iommu_lock);
> -- 
> 2.8.1.dirty
>