linux-kernel - Re: [PATCH 04/04] iommu/ipmmu-vmsa: Add new IOMMU_DOMAIN

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Date:	Thu, 17 Mar 2016 10:35 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	iommu@...ts.linux-foundation.org,
	laurent.pinchart+renesas@...asonboard.com, geert+renesas@...der.be,
	joro@...tes.org, linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org, horms+renesas@...ge.net.au,
	robin.murphy@....com, m.szyprowski@...sung.com
Subject: Re: [PATCH 04/04] iommu/ipmmu-vmsa: Add new IOMMU_DOMAIN_DMA ops

Hi Magnus,

Thank you for the patch.

On Wednesday 16 March 2016 02:05:10 Magnus Damm wrote:
> From: Magnus Damm <damm+renesas@...nsource.se>
> 
> Introduce a new set of iommu_ops suitable for 64-bit ARM
> as well as 32-bit ARM when CONFIG_IOMMU_DMA=y. The ->of_xlate()
> callback is needed by the code exported by of_iommu.h and
> it is wrapped in #ifdefs to also compile of x86_64.
> 
> Signed-off-by: Magnus Damm <damm+renesas@...nsource.se>

Nice work, thanks a lot. With the two comments below addressed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
> 
>  drivers/iommu/ipmmu-vmsa.c |   94 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 92 insertions(+), 2 deletions(-)
> 
> --- 0011/drivers/iommu/ipmmu-vmsa.c
> +++ work/drivers/iommu/ipmmu-vmsa.c	2016-03-16 01:35:06.990513000 +0900
> @@ -10,6 +10,7 @@
> 
>  #include <linux/bitmap.h>
>  #include <linux/delay.h>
> +#include <linux/dma-iommu.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/err.h>
>  #include <linux/export.h>
> @@ -804,7 +805,7 @@ static void ipmmu_remove_device(struct d
>  	dev->archdata.iommu = NULL;
>  }
> 
> -static const struct iommu_ops ipmmu_ops = {
> +static const struct iommu_ops __maybe_unused ipmmu_ops = {
>  	.domain_alloc = ipmmu_domain_alloc,
>  	.domain_free = ipmmu_domain_free,
>  	.attach_dev = ipmmu_attach_device,
> @@ -818,6 +819,92 @@ static const struct iommu_ops ipmmu_ops
>  	.pgsize_bitmap = SZ_1G | SZ_2M | SZ_4K,
>  };
> 
> +static struct iommu_domain *ipmmu_domain_alloc_dma(unsigned type)
> +{
> +	struct iommu_domain *io_domain;
> +
> +	if (type != IOMMU_DOMAIN_DMA)
> +		return NULL;
> +
> +	io_domain = __ipmmu_domain_alloc(type);
> +	if (io_domain)
> +		iommu_get_dma_cookie(io_domain);
> +
> +	return io_domain;
> +}
> +
> +static void ipmmu_domain_free_dma(struct iommu_domain *io_domain)
> +{
> +	iommu_put_dma_cookie(io_domain);
> +	ipmmu_domain_free(io_domain);
> +}
> +
> +static int ipmmu_add_device_dma(struct device *dev)
> +{
> +	struct iommu_group *group;
> +
> +	/* only accept devices with iommus property */

Nitpicking, the driver capitalizes the first letter of the sentence in 
comments and includes a period at the end. Could you please follow the same 
style for consistency ?

> +	if (of_count_phandle_with_args(dev->of_node, "iommus",
> +				       "#iommu-cells") < 0)
> +		return -ENODEV;

Given that the iommu_group_get_for_dev() call will call the .device_group() 
operation that ends up calling ipmmu_init_platform_device(), do we need this 
check here ?

> +	group = iommu_group_get_for_dev(dev);
> +	if (IS_ERR(group))
> +		return PTR_ERR(group);
> +
> +	return 0;
> +}
> +
> +static void ipmmu_remove_device_dma(struct device *dev)
> +{
> +	iommu_group_remove_device(dev);
> +}
> +
> +static struct iommu_group *ipmmu_device_group_dma(struct device *dev)
> +{
> +	struct iommu_group *group;
> +	int ret;
> +
> +	group = generic_device_group(dev);
> +	if (IS_ERR(group))
> +		return group;
> +
> +	ret = ipmmu_init_platform_device(dev, group);
> +	if (ret) {
> +		iommu_group_put(group);
> +		group = ERR_PTR(ret);
> +	}
> +
> +	return group;
> +}
> +
> +#ifdef CONFIG_OF_IOMMU
> +static int ipmmu_of_xlate_dma(struct device *dev,
> +			      struct of_phandle_args *spec)
> +{
> +	/* dummy callback to satisfy of_iommu_configure() */
> +	return 0;
> +}
> +#endif
> +
> +static const struct iommu_ops __maybe_unused ipmmu_ops_dma = {
> +	.domain_alloc = ipmmu_domain_alloc_dma,
> +	.domain_free = ipmmu_domain_free_dma,
> +	.attach_dev = ipmmu_attach_device,
> +	.detach_dev = ipmmu_detach_device,
> +	.map = ipmmu_map,
> +	.unmap = ipmmu_unmap,
> +	.map_sg = default_iommu_map_sg,
> +	.iova_to_phys = ipmmu_iova_to_phys,
> +	.add_device = ipmmu_add_device_dma,
> +	.remove_device = ipmmu_remove_device_dma,
> +	.device_group = ipmmu_device_group_dma,
> +	.pgsize_bitmap = SZ_1G | SZ_2M | SZ_4K,
> +#ifdef CONFIG_OF_IOMMU
> +	.of_xlate = ipmmu_of_xlate_dma,
> +#endif
> +};
> +
>  /*
> ---------------------------------------------------------------------------
> -- * Probe/remove and init
>   */
> @@ -929,14 +1016,17 @@ static struct platform_driver ipmmu_driv
> 
>  static int __init ipmmu_init(void)
>  {
> +	const struct iommu_ops *ops;
>  	int ret;
> 
>  	ret = platform_driver_register(&ipmmu_driver);
>  	if (ret < 0)
>  		return ret;
> 
> +	ops = IS_ENABLED(CONFIG_IOMMU_DMA) ? &ipmmu_ops_dma : &ipmmu_ops;
> +
>  	if (!iommu_present(&platform_bus_type))
> -		bus_set_iommu(&platform_bus_type, &ipmmu_ops);
> +		bus_set_iommu(&platform_bus_type, ops);
> 
>  	return 0;
>  }

-- 
Regards,

Laurent Pinchart