Re: [PATCH v3 3/3] arm,smmu: add support for generic DT bindings. Implement add_device and dt_xlate.

[Rahul Singh <Rahul.Singh@arm.com>]

Hello Stefano,

> On 26 Jan 2021, at 10:58 pm, Stefano Stabellini <sstabellini@kernel.org> wrote:
> 
> From: Brian Woods <brian.woods@xilinx.com>
> 
> Now that all arm iommu drivers support generic bindings we can remove
> the workaround from iommu_add_dt_device().
> 
> Note that if both legacy bindings and generic bindings are present in
> device tree, the legacy bindings are the ones that are used.
> 
> Signed-off-by: Brian Woods <brian.woods@xilinx.com>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>

Reviewed-by: Rahul Singh <rahul.singh@arm.com>
Tested-by: Rahul Singh <rahul.singh@arm.com>

Regards,
Rahul
> ---
> Changes in v3:
> - split patch
> - make find_smmu return non-const so that we can use it in arm_smmu_dt_add_device_generic
> - use dt_phandle_args
> - update commit message
> ---
> xen/drivers/passthrough/arm/smmu.c    | 40 ++++++++++++++++++++++++++-
> xen/drivers/passthrough/device_tree.c | 17 +-----------
> 2 files changed, 40 insertions(+), 17 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/smmu.c b/xen/drivers/passthrough/arm/smmu.c
> index 9687762283..620ba5a4b5 100644
> --- a/xen/drivers/passthrough/arm/smmu.c
> +++ b/xen/drivers/passthrough/arm/smmu.c
> @@ -254,6 +254,8 @@ struct iommu_group
> 	atomic_t ref;
> };
> 
> +static struct arm_smmu_device *find_smmu(const struct device *dev);
> +
> static struct iommu_group *iommu_group_alloc(void)
> {
> 	struct iommu_group *group = xzalloc(struct iommu_group);
> @@ -843,6 +845,40 @@ static int register_smmu_master(struct arm_smmu_device *smmu,
> 					     fwspec);
> }
> 
> +static int arm_smmu_dt_add_device_generic(u8 devfn, struct device *dev)
> +{
> +	struct arm_smmu_device *smmu;
> +	struct iommu_fwspec *fwspec;
> +
> +	fwspec = dev_iommu_fwspec_get(dev);
> +	if (fwspec == NULL)
> +		return -ENXIO;
> +
> +	smmu = find_smmu(fwspec->iommu_dev);
> +	if (smmu == NULL)
> +		return -ENXIO;
> +
> +	return arm_smmu_dt_add_device_legacy(smmu, dev, fwspec);
> +}
> +
> +static int arm_smmu_dt_xlate_generic(struct device *dev,
> +				    const struct dt_phandle_args *spec)
> +{
> +	uint32_t mask, fwid = 0;
> +
> +	if (spec->args_count > 0)
> +		fwid |= (SMR_ID_MASK & spec->args[0]) << SMR_ID_SHIFT;
> +
> +	if (spec->args_count > 1)
> +		fwid |= (SMR_MASK_MASK & spec->args[1]) << SMR_MASK_SHIFT;
> +	else if (!of_property_read_u32(spec->np, "stream-match-mask", &mask))
> +		fwid |= (SMR_MASK_MASK & mask) << SMR_MASK_SHIFT;
> +
> +	return iommu_fwspec_add_ids(dev,
> +				    &fwid,
> +				    1);
> +}
> +
> static struct arm_smmu_device *find_smmu_for_device(struct device *dev)
> {
> 	struct arm_smmu_device *smmu;
> @@ -2766,6 +2802,7 @@ static void arm_smmu_iommu_domain_teardown(struct domain *d)
> static const struct iommu_ops arm_smmu_iommu_ops = {
>     .init = arm_smmu_iommu_domain_init,
>     .hwdom_init = arm_smmu_iommu_hwdom_init,
> +    .add_device = arm_smmu_dt_add_device_generic,
>     .teardown = arm_smmu_iommu_domain_teardown,
>     .iotlb_flush = arm_smmu_iotlb_flush,
>     .iotlb_flush_all = arm_smmu_iotlb_flush_all,
> @@ -2773,9 +2810,10 @@ static const struct iommu_ops arm_smmu_iommu_ops = {
>     .reassign_device = arm_smmu_reassign_dev,
>     .map_page = arm_iommu_map_page,
>     .unmap_page = arm_iommu_unmap_page,
> +    .dt_xlate = arm_smmu_dt_xlate_generic,
> };
> 
> -static __init const struct arm_smmu_device *find_smmu(const struct device *dev)
> +static struct arm_smmu_device *find_smmu(const struct device *dev)
> {
> 	struct arm_smmu_device *smmu;
> 	bool found = false;
> diff --git a/xen/drivers/passthrough/device_tree.c b/xen/drivers/passthrough/device_tree.c
> index a51ae3c9c3..ae07f272e1 100644
> --- a/xen/drivers/passthrough/device_tree.c
> +++ b/xen/drivers/passthrough/device_tree.c
> @@ -162,22 +162,7 @@ int iommu_add_dt_device(struct dt_device_node *np)
>          * these callback implemented.
>          */
>         if ( !ops->add_device || !ops->dt_xlate )
> -        {
> -            /*
> -             * Some Device Trees may expose both legacy SMMU and generic
> -             * IOMMU bindings together. However, the SMMU driver is only
> -             * supporting the former and will protect them during the
> -             * initialization. So we need to skip them and not return
> -             * error here.
> -             *
> -             * XXX: This can be dropped when the SMMU is able to deal
> -             * with generic bindings.
> -             */
> -            if ( dt_device_is_protected(np) )
> -                return 0;
> -            else
> -                return -EINVAL;
> -        }
> +            return -EINVAL;
> 
>         if ( !dt_device_is_available(iommu_spec.np) )
>             break;
> -- 
> 2.17.1
>