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

[Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>]

On 3/1/2026 3:16 PM, Marc Zyngier wrote:
> On Sun, 01 Mar 2026 08:34:19 +0000,
> Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx> wrote:
>>
>> From: Robin Murphy <robin.murphy@xxxxxxx>
>>
>> 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) <robh@xxxxxxxxxx>
>> Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
>> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
>> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>
>> ---
>>  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 <maz@xxxxxxxxxx>
> 
>       M.
> 

Thanks Marc.

I made them static inline mainly because they’re just trivial wrappers
around of_map_id(), so keeping them in include/linux/of.h avoids adding
new global symbols/exports and keeps the callsites simple (similar to
the existing of_property_read_*() inline wrappers).

That said, I don’t have a strong preference—if you’d rather have
out-of-line helpers in drivers/of/base.c, I’m happy to respin accordingly.

Re Documentation, Sure I'll add comments for of_map_iommu_id() and
of_map_msi_id() in follow up patch.

Thanks,
Vijay