Subject: Re: [PATCH v9 1/3] of: Add convenience wrappers for of_map_id()

From: Marc Zyngier <[email-masked]>
Date: Sun, 01 Mar 2026 09:46:34 +0000

On Sun, 01 Mar 2026 08:34:19 +0000,
Vijayanand Jitta <[email-masked]> wrote:
> 
> From: Robin Murphy <[email-masked]>
> 
> Since we now have quite a few users parsing "iommu-map" and "msi-map"
> properties, give them some wrappers to conveniently encapsulate the
> appropriate sets of property names. This will also make it easier to
> then change of_map_id() to correctly account for specifier cells.
> 
> Reviewed-by: Rob Herring (Arm) <[email-masked]>
> Reviewed-by: Frank Li <[email-masked]>
> Signed-off-by: Robin Murphy <[email-masked]>
> Signed-off-by: Vijayanand Jitta <[email-masked]>
> ---
>  drivers/cdx/cdx_msi.c                    |  3 +--
>  drivers/iommu/of_iommu.c                 |  4 +---
>  drivers/irqchip/irq-gic-its-msi-parent.c |  2 +-
>  drivers/of/irq.c                         |  3 +--
>  drivers/pci/controller/dwc/pci-imx6.c    |  6 ++----
>  drivers/pci/controller/pcie-apple.c      |  3 +--
>  drivers/xen/grant-dma-ops.c              |  3 +--
>  include/linux/of.h                       | 14 ++++++++++++++
>  8 files changed, 22 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/cdx/cdx_msi.c b/drivers/cdx/cdx_msi.c
> index 91b95422b263..63b3544ec997 100644
> --- a/drivers/cdx/cdx_msi.c
> +++ b/drivers/cdx/cdx_msi.c
> @@ -128,8 +128,7 @@ static int cdx_msi_prepare(struct irq_domain *msi_domain,
>  	int ret;
>  
>  	/* Retrieve device ID from requestor ID using parent device */
> -	ret = of_map_id(parent->of_node, cdx_dev->msi_dev_id, "msi-map", "msi-map-mask",
> -			NULL, &dev_id);
> +	ret = of_map_msi_id(parent->of_node, cdx_dev->msi_dev_id, NULL, &dev_id);
>  	if (ret) {
>  		dev_err(dev, "of_map_id failed for MSI: %d\n", ret);
>  		return ret;
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index 6b989a62def2..a511ecf21fcd 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -48,9 +48,7 @@ static int of_iommu_configure_dev_id(struct device_node *master_np,
>  	struct of_phandle_args iommu_spec = { .args_count = 1 };
>  	int err;
>  
> -	err = of_map_id(master_np, *id, "iommu-map",
> -			 "iommu-map-mask", &iommu_spec.np,
> -			 iommu_spec.args);
> +	err = of_map_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
>  	if (err)
>  		return err;
>  
> diff --git a/drivers/irqchip/irq-gic-its-msi-parent.c b/drivers/irqchip/irq-gic-its-msi-parent.c
> index d36b278ae66c..b63343a227a9 100644
> --- a/drivers/irqchip/irq-gic-its-msi-parent.c
> +++ b/drivers/irqchip/irq-gic-its-msi-parent.c
> @@ -180,7 +180,7 @@ static int of_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev, u
>  
>  	struct device_node *msi_ctrl __free(device_node) = NULL;
>  
> -	return of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &msi_ctrl, dev_id);
> +	return of_map_msi_id(dev->of_node, dev->id, &msi_ctrl, dev_id);
>  }
>  
>  static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 6367c67732d2..e37c1b3f8736 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -817,8 +817,7 @@ u32 of_msi_xlate(struct device *dev, struct device_node **msi_np, u32 id_in)
>  	 * "msi-map" or an "msi-parent" property.
>  	 */
>  	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent) {
> -		if (!of_map_id(parent_dev->of_node, id_in, "msi-map",
> -				"msi-map-mask", msi_np, &id_out))
> +		if (!of_map_msi_id(parent_dev->of_node, id_in, msi_np, &id_out))
>  			break;
>  		if (!of_check_msi_parent(parent_dev->of_node, msi_np))
>  			break;
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index a5b8d0b71677..bff8289f804a 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1144,8 +1144,7 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
>  	u32 sid = 0;
>  
>  	target = NULL;
> -	err_i = of_map_id(dev->of_node, rid, "iommu-map", "iommu-map-mask",
> -			  &target, &sid_i);
> +	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
>  	if (target) {
>  		of_node_put(target);
>  	} else {
> @@ -1158,8 +1157,7 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
>  	}
>  
>  	target = NULL;
> -	err_m = of_map_id(dev->of_node, rid, "msi-map", "msi-map-mask",
> -			  &target, &sid_m);
> +	err_m = of_map_msi_id(dev->of_node, rid, &target, &sid_m);
>  
>  	/*
>  	 *   err_m      target
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index 2d92fc79f6dd..a0937b7b3c4d 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -764,8 +764,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
>  	dev_dbg(&pdev->dev, "added to bus %s, index %d\n",
>  		pci_name(pdev->bus->self), port->idx);
>  
> -	err = of_map_id(port->pcie->dev->of_node, rid, "iommu-map",
> -			"iommu-map-mask", NULL, &sid);
> +	err = of_map_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
>  	if (err)
>  		return err;
>  
> diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
> index c2603e700178..1b7696b2d762 100644
> --- a/drivers/xen/grant-dma-ops.c
> +++ b/drivers/xen/grant-dma-ops.c
> @@ -325,8 +325,7 @@ static int xen_dt_grant_init_backend_domid(struct device *dev,
>  		struct pci_dev *pdev = to_pci_dev(dev);
>  		u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
>  
> -		if (of_map_id(np, rid, "iommu-map", "iommu-map-mask", &iommu_spec.np,
> -				iommu_spec.args)) {
> +		if (of_map_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
>  			dev_dbg(dev, "Cannot translate ID\n");
>  			return -ESRCH;
>  		}
> diff --git a/include/linux/of.h b/include/linux/of.h
> index be6ec4916adf..824649867810 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -1457,6 +1457,20 @@ static inline int of_property_read_s32(const struct device_node *np,
>  	return of_property_read_u32(np, propname, (u32*) out_value);
>  }
>  
> +static inline int of_map_iommu_id(const struct device_node *np, u32 id,
> +				  struct device_node **target, u32 *id_out)
> +{
> +	return of_map_id(np, id, "iommu-map", "iommu-map-mask",
> +			 target, id_out);
> +}
> +
> +static inline int of_map_msi_id(const struct device_node *np, u32 id,
> +				struct device_node **target, u32 *id_out)
> +{
> +	return of_map_id(np, id, "msi-map", "msi-map-mask",
> +			 target, id_out);
> +}
> +

Any particular reason why this is made inline instead of out of line
in of/base.c? Also, some documentation would be helpful for the
aspiring hackers dipping into this.

Other than that,

Acked-by: Marc Zyngier <[email-masked]>

	M.

-- 
Without deviation from the norm, progress is not possible.