Re: [PATCH 1/2] iommu/tegra: Allow devices to be grouped

[Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Mon, 27 Nov 2017 10:50:54 +0100
Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> 
> Implement the ->device_group() and ->of_xlate() callbacks which are used
> in order to group devices. Each group can then share a single domain.
> 
> This is implemented primarily in order to achieve the same semantics on
> Tegra210 and earlier as on Tegra186 where the Tegra SMMU was replaced by
> an ARM SMMU. Users of the IOMMU API can now use the same code to share
> domains between devices, whereas previously they used to attach each
> device individually.
> 
> Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/iommu/tegra-smmu.c | 124 +++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 120 insertions(+), 4 deletions(-)


Acked-by: Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

> 
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 3b6449e2cbf1..8885635d0a3b 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -20,6 +20,12 @@
>  #include <soc/tegra/ahb.h>
>  #include <soc/tegra/mc.h>
>  
> +struct tegra_smmu_group {
> +	struct list_head list;
> +	const struct tegra_smmu_group_soc *soc;
> +	struct iommu_group *group;
> +};
> +
>  struct tegra_smmu {
>  	void __iomem *regs;
>  	struct device *dev;
> @@ -27,6 +33,8 @@ struct tegra_smmu {
>  	struct tegra_mc *mc;
>  	const struct tegra_smmu_soc *soc;
>  
> +	struct list_head groups;
> +
>  	unsigned long pfn_mask;
>  	unsigned long tlb_mask;
>  
> @@ -703,19 +711,47 @@ static struct tegra_smmu *tegra_smmu_find(struct device_node *np)
>  	return mc->smmu;
>  }
>  
> +static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev,
> +				struct of_phandle_args *args)
> +{
> +	const struct iommu_ops *ops = smmu->iommu.ops;
> +	int err;
> +
> +	err = iommu_fwspec_init(dev, &dev->of_node->fwnode, ops);
> +	if (err < 0) {
> +		dev_err(dev, "failed to initialize fwspec: %d\n", err);
> +		return err;
> +	}
> +
> +	err = ops->of_xlate(dev, args);
> +	if (err < 0) {
> +		dev_err(dev, "failed to parse SW group ID: %d\n", err);
> +		iommu_fwspec_free(dev);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
>  static int tegra_smmu_add_device(struct device *dev)
>  {
>  	struct device_node *np = dev->of_node;
> +	struct tegra_smmu *smmu = NULL;
>  	struct iommu_group *group;
>  	struct of_phandle_args args;
>  	unsigned int index = 0;
> +	int err;
>  
>  	while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
>  					  &args) == 0) {
> -		struct tegra_smmu *smmu;
> -
>  		smmu = tegra_smmu_find(args.np);
>  		if (smmu) {
> +			err = tegra_smmu_configure(smmu, dev, &args);
> +			of_node_put(args.np);
> +
> +			if (err < 0)
> +				return err;
> +
>  			/*
>  			 * Only a single IOMMU master interface is currently
>  			 * supported by the Linux kernel, so abort after the
> @@ -728,9 +764,13 @@ static int tegra_smmu_add_device(struct device *dev)
>  			break;
>  		}
>  
> +		of_node_put(args.np);
>  		index++;
>  	}
>  
> +	if (!smmu)
> +		return -ENODEV;
> +
>  	group = iommu_group_get_for_dev(dev);
>  	if (IS_ERR(group))
>  		return PTR_ERR(group);
> @@ -751,6 +791,80 @@ static void tegra_smmu_remove_device(struct device *dev)
>  	iommu_group_remove_device(dev);
>  }
>  
> +static const struct tegra_smmu_group_soc *
> +tegra_smmu_find_group(struct tegra_smmu *smmu, unsigned int swgroup)
> +{
> +	unsigned int i, j;
> +
> +	for (i = 0; i < smmu->soc->num_groups; i++)
> +		for (j = 0; j < smmu->soc->groups[i].num_swgroups; j++)
> +			if (smmu->soc->groups[i].swgroups[j] == swgroup)
> +				return &smmu->soc->groups[i];
> +
> +	return NULL;
> +}
> +
> +static struct iommu_group *tegra_smmu_group_get(struct tegra_smmu *smmu,
> +						unsigned int swgroup)
> +{
> +	const struct tegra_smmu_group_soc *soc;
> +	struct tegra_smmu_group *group;
> +
> +	soc = tegra_smmu_find_group(smmu, swgroup);
> +	if (!soc)
> +		return NULL;
> +
> +	mutex_lock(&smmu->lock);
> +
> +	list_for_each_entry(group, &smmu->groups, list)
> +		if (group->soc == soc) {
> +			mutex_unlock(&smmu->lock);
> +			return group->group;
> +		}
> +
> +	group = devm_kzalloc(smmu->dev, sizeof(*group), GFP_KERNEL);
> +	if (!group) {
> +		mutex_unlock(&smmu->lock);
> +		return NULL;
> +	}
> +
> +	INIT_LIST_HEAD(&group->list);
> +	group->soc = soc;
> +
> +	group->group = iommu_group_alloc();
> +	if (!group->group) {
> +		devm_kfree(smmu->dev, group);
> +		mutex_unlock(&smmu->lock);
> +		return NULL;
> +	}
> +
> +	list_add_tail(&group->list, &smmu->groups);
> +	mutex_unlock(&smmu->lock);
> +
> +	return group->group;
> +}
> +
> +static struct iommu_group *tegra_smmu_device_group(struct device *dev)
> +{
> +	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> +	struct tegra_smmu *smmu = dev->archdata.iommu;
> +	struct iommu_group *group;
> +
> +	group = tegra_smmu_group_get(smmu, fwspec->ids[0]);
> +	if (!group)
> +		group = generic_device_group(dev);
> +
> +	return group;
> +}
> +
> +static int tegra_smmu_of_xlate(struct device *dev,
> +			       struct of_phandle_args *args)
> +{
> +	u32 id = args->args[0];
> +
> +	return iommu_fwspec_add_ids(dev, &id, 1);
> +}
> +
>  static const struct iommu_ops tegra_smmu_ops = {
>  	.capable = tegra_smmu_capable,
>  	.domain_alloc = tegra_smmu_domain_alloc,
> @@ -759,12 +873,12 @@ static const struct iommu_ops tegra_smmu_ops = {
>  	.detach_dev = tegra_smmu_detach_dev,
>  	.add_device = tegra_smmu_add_device,
>  	.remove_device = tegra_smmu_remove_device,
> -	.device_group = generic_device_group,
> +	.device_group = tegra_smmu_device_group,
>  	.map = tegra_smmu_map,
>  	.unmap = tegra_smmu_unmap,
>  	.map_sg = default_iommu_map_sg,
>  	.iova_to_phys = tegra_smmu_iova_to_phys,
> -
> +	.of_xlate = tegra_smmu_of_xlate,
>  	.pgsize_bitmap = SZ_4K,
>  };
>  
> @@ -913,6 +1027,7 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  	if (!smmu->asids)
>  		return ERR_PTR(-ENOMEM);
>  
> +	INIT_LIST_HEAD(&smmu->groups);
>  	mutex_init(&smmu->lock);
>  
>  	smmu->regs = mc->regs;
> @@ -954,6 +1069,7 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  		return ERR_PTR(err);
>  
>  	iommu_device_set_ops(&smmu->iommu, &tegra_smmu_ops);
> +	iommu_device_set_fwnode(&smmu->iommu, dev->fwnode);
>  
>  	err = iommu_device_register(&smmu->iommu);
>  	if (err) {