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Subject: Re: [RESEND PATCH v6 14/14] iommu/rockchip: Support sharing IOMMU
 between masters
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: <20180301101837.27969-1-jeffy.chen@rock-chips.com>
 <20180301101837.27969-15-jeffy.chen@rock-chips.com>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <44efebd3-ab48-4e12-cf92-66b6563f7644@arm.com>
Date:   Thu, 1 Mar 2018 11:03:38 +0000
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On 01/03/18 10:18, Jeffy Chen wrote:
> There would be some masters sharing the same IOMMU device. Put them in
> the same iommu group and share the same iommu domain.
> 
> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> ---
> 
> Changes in v6: None
> Changes in v5: None
> Changes in v4: None
> Changes in v3:
> Remove rk_iommudata->domain.
> 
> Changes in v2: None
> 
>   drivers/iommu/rockchip-iommu.c | 22 ++++++++++++++++++++--
>   1 file changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index 0e0a42f41818..f4ce7706fc34 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -104,6 +104,7 @@ struct rk_iommu {
>   	struct iommu_device iommu;
>   	struct list_head node; /* entry in rk_iommu_domain.iommus */
>   	struct iommu_domain *domain; /* domain to which iommu is attached */
> +	struct iommu_group *group;
>   };
>   
>   struct rk_iommudata {
> @@ -1083,6 +1084,15 @@ static void rk_iommu_remove_device(struct device *dev)
>   	iommu_group_remove_device(dev);
>   }
>   
> +static struct iommu_group *rk_iommu_device_group(struct device *dev)
> +{
> +	struct rk_iommu *iommu;
> +
> +	iommu = rk_iommu_from_dev(dev);
> +
> +	return iommu->group;

Oops, seems I overlooked this in my previous review - it should really be:

	return iommu_group_get(iommu->group);

or the refcounting will be unbalanced on those future systems where it 
really will be called more than once.

Robin.

> +}
> +
>   static int rk_iommu_of_xlate(struct device *dev,
>   			     struct of_phandle_args *args)
>   {
> @@ -1114,7 +1124,7 @@ static const struct iommu_ops rk_iommu_ops = {
>   	.add_device = rk_iommu_add_device,
>   	.remove_device = rk_iommu_remove_device,
>   	.iova_to_phys = rk_iommu_iova_to_phys,
> -	.device_group = generic_device_group,
> +	.device_group = rk_iommu_device_group,
>   	.pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP,
>   	.of_xlate = rk_iommu_of_xlate,
>   };
> @@ -1183,9 +1193,15 @@ static int rk_iommu_probe(struct platform_device *pdev)
>   	if (err)
>   		return err;
>   
> +	iommu->group = iommu_group_alloc();
> +	if (IS_ERR(iommu->group)) {
> +		err = PTR_ERR(iommu->group);
> +		goto err_unprepare_clocks;
> +	}
> +
>   	err = iommu_device_sysfs_add(&iommu->iommu, dev, NULL, dev_name(dev));
>   	if (err)
> -		goto err_unprepare_clocks;
> +		goto err_put_group;
>   
>   	iommu_device_set_ops(&iommu->iommu, &rk_iommu_ops);
>   	iommu_device_set_fwnode(&iommu->iommu, &dev->of_node->fwnode);
> @@ -1209,6 +1225,8 @@ static int rk_iommu_probe(struct platform_device *pdev)
>   	return 0;
>   err_remove_sysfs:
>   	iommu_device_sysfs_remove(&iommu->iommu);
> +err_put_group:
> +	iommu_group_put(iommu->group);
>   err_unprepare_clocks:
>   	clk_bulk_unprepare(iommu->num_clocks, iommu->clocks);
>   	return err;
>