[PATCH v9 0/3] of: parsing of multi #{iommu,msi}-cells in maps

[PATCH v9 0/3] of: parsing of multi #{iommu,msi}-cells in maps

[Vijayanand Jitta]

So far our parsing of {iommu,msi}-map properites has always blindly
assumed that the output specifiers will always have exactly 1 cell.
This typically does happen to be the case, but is not actually enforced
(and the PCI msi-map binding even explicitly states support for 0 or 1
cells) - as a result we've now ended up with dodgy DTs out in the field
which depend on this behaviour to map a 1-cell specifier for a 2-cell
provider, despite that being bogus per the bindings themselves.

Since there is some potential use[1] in being able to map at least
single input IDs to multi-cell output specifiers (and properly support
0-cell outputs as well), add support for properly parsing and using the
target nodes' #cells values, albeit with the unfortunate complication of
still having to work around expectations of the old behaviour too.
							-- Robin.

Unlike single #{}-cell, it is complex to establish a linear relation
between input 'id' and output specifier for multi-cell properties, thus
it is always expected that len never going to be > 1. 

These changes have been tested on QEMU for the arm64 architecture.

[1] https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@quicinc.com/

V9:
  - Updated TO/CC list based on feedback to include all relevant
    maintainers.
  - No functional changes to the patches themselves.

  Link to V8:
  https://lore.kernel.org/all/20260226074245.3098486-1-vijayanand.jitta@oss.qualcomm.com/

V8:
  - Removed mentions of of_map_args from commit message to match code.

  Link to V7:
  https://lore.kernel.org/all/20260210101157.2145113-1-vijayanand.jitta@oss.qualcomm.com/

V7:
  - Removed of_map_id_args structure and replaced it with
    of_phandle_args as suggested by Dmitry.

  Link to V6:
  https://lore.kernel.org/all/20260121055400.937856-1-vijayanand.jitta@oss.qualcomm.com/

V6:
  - Fixed build error reported by kernel test bot.

  Link to V5:
  https://lore.kernel.org/all/20260118181125.1436036-1-vijayanand.jitta@oss.qualcomm.com/

V5:
  - Fixed Build Warnings.
  - Raised PR for iommu-map dtschema: https://github.com/devicetree-org/dt-schema/pull/184

  Link to V4:
  https://lore.kernel.org/all/20251231114257.2382820-1-vijayanand.jitta@oss.qualcomm.com/

V4:
  - Added Reviewed-by tag.
  - Resolved warnings reported by kernel test bot, minor code
    reorganization.

  Link to V3:
  https://lore.kernel.org/all/20251221213602.2413124-1-vijayanand.jitta@oss.qualcomm.com/

V3:
  - Added Reviewed-by tag.
  - Updated of_map_id_args struct as a wrapper to of_phandle_args and
    added comment description as suggested by Rob Herring.

  Link to V2:
  https://lore.kernel.org/all/20251204095530.8627-1-vijayanand.jitta@oss.qualcomm.com/

V2:
  - Incorporated the patches from Robin that does the clean implementation.
  - Dropped the patches the were adding multi-map support from this series
    as suggested.

V1:
 https://lore.kernel.org/all/cover.1762235099.git.charan.kalla@oss.qualcomm.com/

RFC:
 https://lore.kernel.org/all/20250928171718.436440-1-charan.kalla@oss.qualcomm.com/#r

Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
Charan Teja Kalla (1):
      of: factor arguments passed to of_map_id() into a struct

Robin Murphy (2):
      of: Add convenience wrappers for of_map_id()
      of: Respect #{iommu,msi}-cells in maps

 drivers/cdx/cdx_msi.c                    |   3 +-
 drivers/iommu/of_iommu.c                 |   6 +-
 drivers/irqchip/irq-gic-its-msi-parent.c |   2 +-
 drivers/of/base.c                        | 148 ++++++++++++++++++++++---------
 drivers/of/irq.c                         |   3 +-
 drivers/pci/controller/dwc/pci-imx6.c    |  12 ++-
 drivers/pci/controller/pcie-apple.c      |   5 +-
 drivers/xen/grant-dma-ops.c              |   3 +-
 include/linux/of.h                       |  33 +++++--
 9 files changed, 152 insertions(+), 63 deletions(-)
---
base-commit: 3fa5e5702a82d259897bd7e209469bc06368bf31
change-id: 20260301-parse_iommu_cells-1c33768aebba

Best regards,
-- 
Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>

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

[Vijayanand Jitta]

From: Robin Murphy <robin.murphy@arm.com>

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@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
 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);
+}
+
 #define of_for_each_phandle(it, err, np, ln, cn, cc)			\
 	for (of_phandle_iterator_init((it), (np), (ln), (cn), (cc)),	\
 	     err = of_phandle_iterator_next(it);			\

-- 
2.34.1

[PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Vijayanand Jitta]

From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>

Change of_map_id() to take a pointer to struct of_phandle_args
instead of passing target device node and translated IDs separately.
Update all callers accordingly.

Subsequent patch will make use of the args_count field in
struct of_phandle_args.

Suggested-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
 drivers/iommu/of_iommu.c              |  2 +-
 drivers/of/base.c                     | 37 +++++++++++++++++------------------
 drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
 drivers/pci/controller/pcie-apple.c   |  4 +++-
 drivers/xen/grant-dma-ops.c           |  2 +-
 include/linux/of.h                    | 21 +++++++++++++-------
 6 files changed, 44 insertions(+), 30 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index a511ecf21fcd..d255d0f58e8c 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -48,7 +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_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
+	err = of_map_iommu_id(master_np, *id, &iommu_spec);
 	if (err)
 		return err;
 
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 57420806c1a2..6c3628255908 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2102,8 +2102,11 @@ int of_find_last_cache_level(unsigned int cpu)
  * @id: device ID to map.
  * @map_name: property name of the map to use.
  * @map_mask_name: optional property name of the mask to use.
- * @target: optional pointer to a target device node.
- * @id_out: optional pointer to receive the translated ID.
+ * @arg: of_phandle_args structure,
+ *	which includes:
+ *	np: pointer to the target device node
+ *	args_count: number of arguments
+ *	args[]: array to receive the translated ID(s).
  *
  * Given a device ID, look up the appropriate implementation-defined
  * platform ID and/or the target device which receives transactions on that
@@ -2117,21 +2120,21 @@ int of_find_last_cache_level(unsigned int cpu)
  */
 int of_map_id(const struct device_node *np, u32 id,
 	       const char *map_name, const char *map_mask_name,
-	       struct device_node **target, u32 *id_out)
+	       struct of_phandle_args *arg)
 {
 	u32 map_mask, masked_id;
 	int map_len;
 	const __be32 *map = NULL;
 
-	if (!np || !map_name || (!target && !id_out))
+	if (!np || !map_name || !arg)
 		return -EINVAL;
 
 	map = of_get_property(np, map_name, &map_len);
 	if (!map) {
-		if (target)
+		if (arg->np)
 			return -ENODEV;
 		/* Otherwise, no map implies no translation */
-		*id_out = id;
+		arg->args[0] = id;
 		return 0;
 	}
 
@@ -2173,18 +2176,15 @@ int of_map_id(const struct device_node *np, u32 id,
 		if (!phandle_node)
 			return -ENODEV;
 
-		if (target) {
-			if (*target)
-				of_node_put(phandle_node);
-			else
-				*target = phandle_node;
+		if (arg->np)
+			of_node_put(phandle_node);
+		else
+			arg->np = phandle_node;
 
-			if (*target != phandle_node)
-				continue;
-		}
+		if (arg->np != phandle_node)
+			continue;
 
-		if (id_out)
-			*id_out = masked_id - id_base + out_base;
+		arg->args[0] = masked_id - id_base + out_base;
 
 		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
 			np, map_name, map_mask, id_base, out_base,
@@ -2193,11 +2193,10 @@ int of_map_id(const struct device_node *np, u32 id,
 	}
 
 	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
-		id, target && *target ? *target : NULL);
+		id, arg->np ? arg->np : NULL);
 
 	/* Bypasses translation */
-	if (id_out)
-		*id_out = id;
+	arg->args[0] = id;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_map_id);
diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index bff8289f804a..74fc603b3f84 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1139,12 +1139,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
 {
 	struct device *dev = imx_pcie->pci->dev;
 	struct device_node *target;
+	struct of_phandle_args iommu_spec = { .args_count = 1 };
 	u32 sid_i, sid_m;
 	int err_i, err_m;
 	u32 sid = 0;
 
 	target = NULL;
-	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
+	err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec);
+	if (!err_i) {
+		target = iommu_spec.np;
+		sid_i = iommu_spec.args[0];
+	}
+
 	if (target) {
 		of_node_put(target);
 	} else {
diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index a0937b7b3c4d..e1d4b37d200d 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
 {
 	u32 sid, rid = pci_dev_id(pdev);
 	struct apple_pcie_port *port;
+	struct of_phandle_args iommu_spec = { .args_count = 1 };
 	int idx, err;
 
 	port = apple_pcie_get_port(pdev);
@@ -764,10 +765,11 @@ 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_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
+	err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec);
 	if (err)
 		return err;
 
+	sid = iommu_spec.args[0];
 	mutex_lock(&port->pcie->lock);
 
 	idx = bitmap_find_free_region(port->sid_map, port->sid_map_sz, 0);
diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index 1b7696b2d762..5f1d6540049a 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -325,7 +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_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
+		if (of_map_iommu_id(np, rid, &iommu_spec)) {
 			dev_dbg(dev, "Cannot translate ID\n");
 			return -ESRCH;
 		}
diff --git a/include/linux/of.h b/include/linux/of.h
index 824649867810..9d72d76f909d 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -463,7 +463,7 @@ bool of_console_check(const struct device_node *dn, char *name, int index);
 
 int of_map_id(const struct device_node *np, u32 id,
 	       const char *map_name, const char *map_mask_name,
-	       struct device_node **target, u32 *id_out);
+	       struct of_phandle_args *arg);
 
 phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
 
@@ -929,7 +929,7 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
 
 static inline int of_map_id(const struct device_node *np, u32 id,
 			     const char *map_name, const char *map_mask_name,
-			     struct device_node **target, u32 *id_out)
+			     struct of_phandle_args *arg)
 {
 	return -EINVAL;
 }
@@ -1458,17 +1458,24 @@ static inline int of_property_read_s32(const struct device_node *np,
 }
 
 static inline int of_map_iommu_id(const struct device_node *np, u32 id,
-				  struct device_node **target, u32 *id_out)
+				  struct of_phandle_args *arg)
 {
-	return of_map_id(np, id, "iommu-map", "iommu-map-mask",
-			 target, id_out);
+	return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
 }
 
 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);
+	struct of_phandle_args msi_spec = { .np = *target, .args_count = 1 };
+	int ret;
+
+	ret = of_map_id(np, id, "msi-map", "msi-map-mask", &msi_spec);
+	if (!ret) {
+		*target = msi_spec.np;
+		*id_out = msi_spec.args[0];
+	}
+
+	return ret;
 }
 
 #define of_for_each_phandle(it, err, np, ln, cn, cc)			\

-- 
2.34.1

[PATCH v9 3/3] of: Respect #{iommu,msi}-cells in maps

[Vijayanand Jitta]

From: Robin Murphy <robin.murphy@arm.com>

So far our parsing of {iommu,msi}-map properites has always blindly
assumed that the output specifiers will always have exactly 1 cell.
This typically does happen to be the case, but is not actually enforced
(and the PCI msi-map binding even explicitly states support for 0 or 1
cells) - as a result we've now ended up with dodgy DTs out in the field
which depend on this behaviour to map a 1-cell specifier for a 2-cell
provider, despite that being bogus per the bindings themselves.

Since there is some potential use in being able to map at least single
input IDs to multi-cell output specifiers (and properly support 0-cell
outputs as well), add support for properly parsing and using the target
nodes' #cells values, albeit with the unfortunate complication of still
having to work around expectations of the old behaviour too.

Since there are multi-cell output specifiers, the callers of of_map_id()
may need to get the exact cell output value for further processing.
Added support for that part --charan

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
 drivers/iommu/of_iommu.c |   2 +-
 drivers/of/base.c        | 117 +++++++++++++++++++++++++++++++++++++----------
 include/linux/of.h       |  16 +++----
 3 files changed, 102 insertions(+), 33 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index d255d0f58e8c..a18bb60f6f3d 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -45,7 +45,7 @@ static int of_iommu_configure_dev_id(struct device_node *master_np,
 				     struct device *dev,
 				     const u32 *id)
 {
-	struct of_phandle_args iommu_spec = { .args_count = 1 };
+	struct of_phandle_args iommu_spec = {};
 	int err;
 
 	err = of_map_iommu_id(master_np, *id, &iommu_spec);
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 6c3628255908..596bcf993dcb 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2096,11 +2096,38 @@ int of_find_last_cache_level(unsigned int cpu)
 	return cache_level;
 }
 
+/*
+ * Some DTs have an iommu-map targeting a 2-cell IOMMU node while
+ * specifying only 1 cell. Fortunately they all consist of value '1'
+ * as the 2nd cell entry with the same target, so check for that pattern.
+ *
+ * Example:
+ *	IOMMU node:
+ *		#iommu-cells = <2>;
+ *
+ *	Device node:
+ *		iommu-map = <0x0000 &smmu 0x0000 0x1>,
+ *			    <0x0100 &smmu 0x0100 0x1>;
+ */
+static bool of_check_bad_map(const __be32 *map, int len)
+{
+	__be32 phandle = map[1];
+
+	if (len % 4)
+		return false;
+	for (int i = 0; i < len; i += 4) {
+		if (map[i + 1] != phandle || map[i + 3] != cpu_to_be32(1))
+			return false;
+	}
+	return true;
+}
+
 /**
  * of_map_id - Translate an ID through a downstream mapping.
  * @np: root complex device node.
  * @id: device ID to map.
  * @map_name: property name of the map to use.
+ * @cells_name: property name of target specifier cells.
  * @map_mask_name: optional property name of the mask to use.
  * @arg: of_phandle_args structure,
  *	which includes:
@@ -2118,18 +2145,19 @@ int of_find_last_cache_level(unsigned int cpu)
  *
  * Return: 0 on success or a standard error code on failure.
  */
-int of_map_id(const struct device_node *np, u32 id,
-	       const char *map_name, const char *map_mask_name,
-	       struct of_phandle_args *arg)
+int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+	      const char *cells_name, const char *map_mask_name,
+	      struct of_phandle_args *arg)
 {
 	u32 map_mask, masked_id;
-	int map_len;
+	int map_bytes, map_len, offset = 0;
+	bool bad_map = false;
 	const __be32 *map = NULL;
 
 	if (!np || !map_name || !arg)
 		return -EINVAL;
 
-	map = of_get_property(np, map_name, &map_len);
+	map = of_get_property(np, map_name, &map_bytes);
 	if (!map) {
 		if (arg->np)
 			return -ENODEV;
@@ -2138,11 +2166,9 @@ int of_map_id(const struct device_node *np, u32 id,
 		return 0;
 	}
 
-	if (!map_len || map_len % (4 * sizeof(*map))) {
-		pr_err("%pOF: Error: Bad %s length: %d\n", np,
-			map_name, map_len);
-		return -EINVAL;
-	}
+	if (map_bytes % sizeof(*map))
+		goto err_map_len;
+	map_len = map_bytes / sizeof(*map);
 
 	/* The default is to select all bits. */
 	map_mask = 0xffffffff;
@@ -2155,27 +2181,63 @@ int of_map_id(const struct device_node *np, u32 id,
 		of_property_read_u32(np, map_mask_name, &map_mask);
 
 	masked_id = map_mask & id;
-	for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
+
+	while (offset < map_len) {
 		struct device_node *phandle_node;
-		u32 id_base = be32_to_cpup(map + 0);
-		u32 phandle = be32_to_cpup(map + 1);
-		u32 out_base = be32_to_cpup(map + 2);
-		u32 id_len = be32_to_cpup(map + 3);
+		u32 id_base, phandle, id_len, id_off, cells = 0;
+		const __be32 *out_base;
+
+		if (map_len - offset < 2)
+			goto err_map_len;
+
+		id_base = be32_to_cpup(map + offset);
 
 		if (id_base & ~map_mask) {
-			pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
-				np, map_name, map_name,
-				map_mask, id_base);
+			pr_err("%pOF: Invalid %s translation - %s (0x%x) ignores id-base (0x%x)\n",
+			       np, map_name, map_mask_name, map_mask, id_base);
 			return -EFAULT;
 		}
 
-		if (masked_id < id_base || masked_id >= id_base + id_len)
-			continue;
-
+		phandle = be32_to_cpup(map + offset + 1);
 		phandle_node = of_find_node_by_phandle(phandle);
 		if (!phandle_node)
 			return -ENODEV;
 
+		if (!bad_map && of_property_read_u32(phandle_node, cells_name, &cells)) {
+			pr_err("%pOF: missing %s property\n", phandle_node, cells_name);
+			return -EINVAL;
+		}
+
+		if (map_len - offset < 3 + cells)
+			goto err_map_len;
+
+		if (offset == 0 && cells == 2) {
+			bad_map = of_check_bad_map(map, map_len);
+			if (bad_map) {
+				pr_warn_once("%pOF: %s mismatches target %s, assuming extra cell of 0\n",
+					     np, map_name, cells_name);
+				cells = 1;
+			}
+		}
+
+		out_base = map + offset + 2;
+		offset += 3 + cells;
+
+		id_len = be32_to_cpup(map + offset - 1);
+		if (id_len > 1 && cells > 1) {
+			/*
+			 * With 1 output cell we reasonably assume its value
+			 * has a linear relationship to the input; with more,
+			 * we'd need help from the provider to know what to do.
+			 */
+			pr_err("%pOF: Unsupported %s - cannot handle %d-ID range with %d-cell output specifier\n",
+			       np, map_name, id_len, cells);
+			return -EINVAL;
+		}
+		id_off = masked_id - id_base;
+		if (masked_id < id_base || id_off >= id_len)
+			continue;
+
 		if (arg->np)
 			of_node_put(phandle_node);
 		else
@@ -2184,11 +2246,14 @@ int of_map_id(const struct device_node *np, u32 id,
 		if (arg->np != phandle_node)
 			continue;
 
-		arg->args[0] = masked_id - id_base + out_base;
+		for (int i = 0; i < cells; i++)
+			arg->args[i] = (id_off + be32_to_cpu(out_base[i]));
+
+		arg->args_count = cells;
 
 		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
-			np, map_name, map_mask, id_base, out_base,
-			id_len, id, masked_id - id_base + out_base);
+			 np, map_name, map_mask, id_base, be32_to_cpup(out_base),
+			 id_len, id, id_off + be32_to_cpup(out_base));
 		return 0;
 	}
 
@@ -2198,5 +2263,9 @@ int of_map_id(const struct device_node *np, u32 id,
 	/* Bypasses translation */
 	arg->args[0] = id;
 	return 0;
+
+err_map_len:
+	pr_err("%pOF: Error: Bad %s length: %d\n", np, map_name, map_bytes);
+	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(of_map_id);
diff --git a/include/linux/of.h b/include/linux/of.h
index 9d72d76f909d..5b5b5dc2d3f3 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -461,9 +461,9 @@ const char *of_prop_next_string(const struct property *prop, const char *cur);
 
 bool of_console_check(const struct device_node *dn, char *name, int index);
 
-int of_map_id(const struct device_node *np, u32 id,
-	       const char *map_name, const char *map_mask_name,
-	       struct of_phandle_args *arg);
+int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+	      const char *cells_name, const char *map_mask_name,
+	      struct of_phandle_args *arg);
 
 phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
 
@@ -927,9 +927,9 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
 {
 }
 
-static inline int of_map_id(const struct device_node *np, u32 id,
-			     const char *map_name, const char *map_mask_name,
-			     struct of_phandle_args *arg)
+static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+			    const char *cells_name, const char *map_mask_name,
+			    struct of_phandle_args *arg)
 {
 	return -EINVAL;
 }
@@ -1460,7 +1460,7 @@ static inline int of_property_read_s32(const struct device_node *np,
 static inline int of_map_iommu_id(const struct device_node *np, u32 id,
 				  struct of_phandle_args *arg)
 {
-	return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
+	return of_map_id(np, id, "iommu-map", "#iommu-cells", "iommu-map-mask", arg);
 }
 
 static inline int of_map_msi_id(const struct device_node *np, u32 id,
@@ -1469,7 +1469,7 @@ static inline int of_map_msi_id(const struct device_node *np, u32 id,
 	struct of_phandle_args msi_spec = { .np = *target, .args_count = 1 };
 	int ret;
 
-	ret = of_map_id(np, id, "msi-map", "msi-map-mask", &msi_spec);
+	ret = of_map_id(np, id, "msi-map", "#msi-cells", "msi-map-mask", &msi_spec);
 	if (!ret) {
 		*target = msi_spec.np;
 		*id_out = msi_spec.args[0];

-- 
2.34.1

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

[Marc Zyngier]

On Sun, 01 Mar 2026 08:34:19 +0000,
Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> 
> From: Robin Murphy <robin.murphy@arm.com>
> 
> 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@kernel.org>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> ---
>  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@kernel.org>

	M.

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

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Dmitry Baryshkov]

On Sun, Mar 01, 2026 at 02:04:20PM +0530, Vijayanand Jitta wrote:
> From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> 
> Change of_map_id() to take a pointer to struct of_phandle_args
> instead of passing target device node and translated IDs separately.
> Update all callers accordingly.
> 
> Subsequent patch will make use of the args_count field in
> struct of_phandle_args.
> 
> Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> ---
>  drivers/iommu/of_iommu.c              |  2 +-
>  drivers/of/base.c                     | 37 +++++++++++++++++------------------
>  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
>  drivers/pci/controller/pcie-apple.c   |  4 +++-
>  drivers/xen/grant-dma-ops.c           |  2 +-
>  include/linux/of.h                    | 21 +++++++++++++-------
>  6 files changed, 44 insertions(+), 30 deletions(-)
> 

> @@ -2193,11 +2193,10 @@ int of_map_id(const struct device_node *np, u32 id,
>  	}
>  
>  	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
> -		id, target && *target ? *target : NULL);
> +		id, arg->np ? arg->np : NULL);

Is it just 'args->np' then? If it's NULL, it's NULL anyway.

>  
>  	/* Bypasses translation */
> -	if (id_out)
> -		*id_out = id;
> +	arg->args[0] = id;
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(of_map_id);
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index bff8289f804a..74fc603b3f84 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1139,12 +1139,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
>  {
>  	struct device *dev = imx_pcie->pci->dev;
>  	struct device_node *target;
> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
>  	u32 sid_i, sid_m;
>  	int err_i, err_m;
>  	u32 sid = 0;
>  
>  	target = NULL;
> -	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
> +	err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec);
> +	if (!err_i) {
> +		target = iommu_spec.np;
> +		sid_i = iommu_spec.args[0];
> +	}
> +
>  	if (target) {
>  		of_node_put(target);
>  	} else {
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index a0937b7b3c4d..e1d4b37d200d 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
>  {
>  	u32 sid, rid = pci_dev_id(pdev);
>  	struct apple_pcie_port *port;
> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
>  	int idx, err;
>  
>  	port = apple_pcie_get_port(pdev);
> @@ -764,10 +765,11 @@ 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_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
> +	err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec);
>  	if (err)
>  		return err;

of_node_put(iommu_spec.np);

>  
> +	sid = iommu_spec.args[0];
>  	mutex_lock(&port->pcie->lock);
>  
>  	idx = bitmap_find_free_region(port->sid_map, port->sid_map_sz, 0);
> diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
> index 1b7696b2d762..5f1d6540049a 100644
> --- a/drivers/xen/grant-dma-ops.c
> +++ b/drivers/xen/grant-dma-ops.c
> @@ -325,7 +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_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
> +		if (of_map_iommu_id(np, rid, &iommu_spec)) {
>  			dev_dbg(dev, "Cannot translate ID\n");
>  			return -ESRCH;
>  		}
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 824649867810..9d72d76f909d 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -463,7 +463,7 @@ bool of_console_check(const struct device_node *dn, char *name, int index);
>  
>  int of_map_id(const struct device_node *np, u32 id,
>  	       const char *map_name, const char *map_mask_name,
> -	       struct device_node **target, u32 *id_out);
> +	       struct of_phandle_args *arg);
>  
>  phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
>  
> @@ -929,7 +929,7 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
>  
>  static inline int of_map_id(const struct device_node *np, u32 id,
>  			     const char *map_name, const char *map_mask_name,
> -			     struct device_node **target, u32 *id_out)
> +			     struct of_phandle_args *arg)
>  {
>  	return -EINVAL;
>  }
> @@ -1458,17 +1458,24 @@ static inline int of_property_read_s32(const struct device_node *np,
>  }
>  
>  static inline int of_map_iommu_id(const struct device_node *np, u32 id,
> -				  struct device_node **target, u32 *id_out)
> +				  struct of_phandle_args *arg)

Document that it's the caller's responsibility to of_node_put() returned
node. As it can be seen from the previous comment, it's not obvious.

>  {
> -	return of_map_id(np, id, "iommu-map", "iommu-map-mask",
> -			 target, id_out);
> +	return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
>  }
>  
>  static inline int of_map_msi_id(const struct device_node *np, u32 id,
>  				struct device_node **target, u32 *id_out)

Is there a reason for chaning the of_map_iommu_id() args but not
of_map_msi_id() args?

>  {
> -	return of_map_id(np, id, "msi-map", "msi-map-mask",
> -			 target, id_out);
> +	struct of_phandle_args msi_spec = { .np = *target, .args_count = 1 };

Which driver passes something being worth of storing in .np?

> +	int ret;
> +
> +	ret = of_map_id(np, id, "msi-map", "msi-map-mask", &msi_spec);
> +	if (!ret) {
> +		*target = msi_spec.np;
> +		*id_out = msi_spec.args[0];
> +	}
> +
> +	return ret;
>  }
>  
>  #define of_for_each_phandle(it, err, np, ln, cn, cc)			\
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Marc Zyngier]

On Sun, 01 Mar 2026 08:34:20 +0000,
Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> 
> From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> 
> Change of_map_id() to take a pointer to struct of_phandle_args
> instead of passing target device node and translated IDs separately.
> Update all callers accordingly.
> 
> Subsequent patch will make use of the args_count field in
> struct of_phandle_args.
> 
> Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> ---
>  drivers/iommu/of_iommu.c              |  2 +-
>  drivers/of/base.c                     | 37 +++++++++++++++++------------------
>  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
>  drivers/pci/controller/pcie-apple.c   |  4 +++-
>  drivers/xen/grant-dma-ops.c           |  2 +-
>  include/linux/of.h                    | 21 +++++++++++++-------
>  6 files changed, 44 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index a511ecf21fcd..d255d0f58e8c 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -48,7 +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_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
> +	err = of_map_iommu_id(master_np, *id, &iommu_spec);
>  	if (err)
>  		return err;
>  
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 57420806c1a2..6c3628255908 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2102,8 +2102,11 @@ int of_find_last_cache_level(unsigned int cpu)
>   * @id: device ID to map.
>   * @map_name: property name of the map to use.
>   * @map_mask_name: optional property name of the mask to use.
> - * @target: optional pointer to a target device node.
> - * @id_out: optional pointer to receive the translated ID.
> + * @arg: of_phandle_args structure,
> + *	which includes:
> + *	np: pointer to the target device node
> + *	args_count: number of arguments

Number of arguments *to what*? Isn't that the size of args[] instead?

> + *	args[]: array to receive the translated ID(s).
>   *
>   * Given a device ID, look up the appropriate implementation-defined
>   * platform ID and/or the target device which receives transactions on that
> @@ -2117,21 +2120,21 @@ int of_find_last_cache_level(unsigned int cpu)
>   */
>  int of_map_id(const struct device_node *np, u32 id,
>  	       const char *map_name, const char *map_mask_name,
> -	       struct device_node **target, u32 *id_out)
> +	       struct of_phandle_args *arg)
>  {
>  	u32 map_mask, masked_id;
>  	int map_len;
>  	const __be32 *map = NULL;
>  
> -	if (!np || !map_name || (!target && !id_out))
> +	if (!np || !map_name || !arg)
>  		return -EINVAL;
>  
>  	map = of_get_property(np, map_name, &map_len);
>  	if (!map) {
> -		if (target)
> +		if (arg->np)
>  			return -ENODEV;
>  		/* Otherwise, no map implies no translation */
> -		*id_out = id;
> +		arg->args[0] = id;

What if args_count is 0? Given that you place no restriction on the
way this can be called, that'd be entirely legitimate, and you'd
corrupt something you're not supposed to touch.

>  		return 0;
>  	}
>  
> @@ -2173,18 +2176,15 @@ int of_map_id(const struct device_node *np, u32 id,
>  		if (!phandle_node)
>  			return -ENODEV;
>  
> -		if (target) {
> -			if (*target)
> -				of_node_put(phandle_node);
> -			else
> -				*target = phandle_node;
> +		if (arg->np)
> +			of_node_put(phandle_node);
> +		else
> +			arg->np = phandle_node;
>  
> -			if (*target != phandle_node)
> -				continue;
> -		}
> +		if (arg->np != phandle_node)
> +			continue;
>  
> -		if (id_out)
> -			*id_out = masked_id - id_base + out_base;
> +		arg->args[0] = masked_id - id_base + out_base;
>  
>  		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
>  			np, map_name, map_mask, id_base, out_base,
> @@ -2193,11 +2193,10 @@ int of_map_id(const struct device_node *np, u32 id,
>  	}
>  
>  	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
> -		id, target && *target ? *target : NULL);
> +		id, arg->np ? arg->np : NULL);
>  
>  	/* Bypasses translation */
> -	if (id_out)
> -		*id_out = id;
> +	arg->args[0] = id;
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(of_map_id);
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index bff8289f804a..74fc603b3f84 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1139,12 +1139,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
>  {
>  	struct device *dev = imx_pcie->pci->dev;
>  	struct device_node *target;
> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
>  	u32 sid_i, sid_m;
>  	int err_i, err_m;
>  	u32 sid = 0;
>  
>  	target = NULL;
> -	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
> +	err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec);
> +	if (!err_i) {
> +		target = iommu_spec.np;
> +		sid_i = iommu_spec.args[0];
> +	}
> +
>  	if (target) {
>  		of_node_put(target);
>  	} else {
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index a0937b7b3c4d..e1d4b37d200d 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
>  {
>  	u32 sid, rid = pci_dev_id(pdev);
>  	struct apple_pcie_port *port;
> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
>  	int idx, err;
>  
>  	port = apple_pcie_get_port(pdev);
> @@ -764,10 +765,11 @@ 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_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
> +	err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec);
>  	if (err)
>  		return err;
>  
> +	sid = iommu_spec.args[0];

I find this stuff absolutely unreadable. You're fishing the SID in a
random position of a random structure, without any documentation of
how this is supposed to work. This really needs a wrapper that hides
this implementation detail.

Thanks,

	M.

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

Re: [PATCH v9 3/3] of: Respect #{iommu,msi}-cells in maps

[Dmitry Baryshkov]

On Sun, Mar 01, 2026 at 02:04:21PM +0530, Vijayanand Jitta wrote:
> From: Robin Murphy <robin.murphy@arm.com>
> 
> So far our parsing of {iommu,msi}-map properites has always blindly
> assumed that the output specifiers will always have exactly 1 cell.
> This typically does happen to be the case, but is not actually enforced
> (and the PCI msi-map binding even explicitly states support for 0 or 1
> cells) - as a result we've now ended up with dodgy DTs out in the field
> which depend on this behaviour to map a 1-cell specifier for a 2-cell
> provider, despite that being bogus per the bindings themselves.
> 
> Since there is some potential use in being able to map at least single
> input IDs to multi-cell output specifiers (and properly support 0-cell
> outputs as well), add support for properly parsing and using the target
> nodes' #cells values, albeit with the unfortunate complication of still
> having to work around expectations of the old behaviour too.
> 
> Since there are multi-cell output specifiers, the callers of of_map_id()
> may need to get the exact cell output value for further processing.
> Added support for that part --charan
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> ---
>  drivers/iommu/of_iommu.c |   2 +-
>  drivers/of/base.c        | 117 +++++++++++++++++++++++++++++++++++++----------
>  include/linux/of.h       |  16 +++----
>  3 files changed, 102 insertions(+), 33 deletions(-)
> 

>  /**
>   * of_map_id - Translate an ID through a downstream mapping.
>   * @np: root complex device node.
>   * @id: device ID to map.
>   * @map_name: property name of the map to use.
> + * @cells_name: property name of target specifier cells.
>   * @map_mask_name: optional property name of the mask to use.
>   * @arg: of_phandle_args structure,
>   *	which includes:
> @@ -2118,18 +2145,19 @@ int of_find_last_cache_level(unsigned int cpu)
>   *
>   * Return: 0 on success or a standard error code on failure.
>   */
> -int of_map_id(const struct device_node *np, u32 id,
> -	       const char *map_name, const char *map_mask_name,
> -	       struct of_phandle_args *arg)
> +int of_map_id(const struct device_node *np, u32 id, const char *map_name,
> +	      const char *cells_name, const char *map_mask_name,
> +	      struct of_phandle_args *arg)

Some extra whitespace-related noise in here. Last line wasn't changed,
so there is no need to touch it.

>  {
>  	u32 map_mask, masked_id;
> -	int map_len;
> +	int map_bytes, map_len, offset = 0;
> +	bool bad_map = false;
>  	const __be32 *map = NULL;
>  
>  	if (!np || !map_name || !arg)
>  		return -EINVAL;
>  
> -	map = of_get_property(np, map_name, &map_len);
> +	map = of_get_property(np, map_name, &map_bytes);
>  	if (!map) {
>  		if (arg->np)
>  			return -ENODEV;
> @@ -2138,11 +2166,9 @@ int of_map_id(const struct device_node *np, u32 id,
>  		return 0;
>  	}
>  
> -	if (!map_len || map_len % (4 * sizeof(*map))) {
> -		pr_err("%pOF: Error: Bad %s length: %d\n", np,
> -			map_name, map_len);
> -		return -EINVAL;
> -	}
> +	if (map_bytes % sizeof(*map))
> +		goto err_map_len;
> +	map_len = map_bytes / sizeof(*map);
>  
>  	/* The default is to select all bits. */
>  	map_mask = 0xffffffff;
> @@ -2155,27 +2181,63 @@ int of_map_id(const struct device_node *np, u32 id,
>  		of_property_read_u32(np, map_mask_name, &map_mask);
>  
>  	masked_id = map_mask & id;
> -	for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
> +
> +	while (offset < map_len) {
>  		struct device_node *phandle_node;
> -		u32 id_base = be32_to_cpup(map + 0);
> -		u32 phandle = be32_to_cpup(map + 1);
> -		u32 out_base = be32_to_cpup(map + 2);
> -		u32 id_len = be32_to_cpup(map + 3);
> +		u32 id_base, phandle, id_len, id_off, cells = 0;
> +		const __be32 *out_base;
> +
> +		if (map_len - offset < 2)
> +			goto err_map_len;
> +
> +		id_base = be32_to_cpup(map + offset);
>  
>  		if (id_base & ~map_mask) {
> -			pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
> -				np, map_name, map_name,
> -				map_mask, id_base);
> +			pr_err("%pOF: Invalid %s translation - %s (0x%x) ignores id-base (0x%x)\n",
> +			       np, map_name, map_mask_name, map_mask, id_base);
>  			return -EFAULT;
>  		}
>  
> -		if (masked_id < id_base || masked_id >= id_base + id_len)
> -			continue;
> -
> +		phandle = be32_to_cpup(map + offset + 1);
>  		phandle_node = of_find_node_by_phandle(phandle);
>  		if (!phandle_node)
>  			return -ENODEV;
>  
> +		if (!bad_map && of_property_read_u32(phandle_node, cells_name, &cells)) {
> +			pr_err("%pOF: missing %s property\n", phandle_node, cells_name);
> +			return -EINVAL;
> +		}

This will trigger the cells_name property check even if later we
discover that we have a "bad" map. Is it intended / required?

> +
> +		if (map_len - offset < 3 + cells)

of_node_put(phandle_node);

> +			goto err_map_len;
> +
> +		if (offset == 0 && cells == 2) {

... if it's not required, then the bad_map check can be moved before the
loop.

> +			bad_map = of_check_bad_map(map, map_len);
> +			if (bad_map) {
> +				pr_warn_once("%pOF: %s mismatches target %s, assuming extra cell of 0\n",
> +					     np, map_name, cells_name);
> +				cells = 1;
> +			}
> +		}
> +
> +		out_base = map + offset + 2;
> +		offset += 3 + cells;
> +
> +		id_len = be32_to_cpup(map + offset - 1);
> +		if (id_len > 1 && cells > 1) {
> +			/*
> +			 * With 1 output cell we reasonably assume its value
> +			 * has a linear relationship to the input; with more,
> +			 * we'd need help from the provider to know what to do.
> +			 */
> +			pr_err("%pOF: Unsupported %s - cannot handle %d-ID range with %d-cell output specifier\n",
> +			       np, map_name, id_len, cells);
> +			return -EINVAL;
> +		}
> +		id_off = masked_id - id_base;
> +		if (masked_id < id_base || id_off >= id_len)
> +			continue;
> +
>  		if (arg->np)
>  			of_node_put(phandle_node);
>  		else
> @@ -2184,11 +2246,14 @@ int of_map_id(const struct device_node *np, u32 id,
>  		if (arg->np != phandle_node)
>  			continue;
>  
> -		arg->args[0] = masked_id - id_base + out_base;
> +		for (int i = 0; i < cells; i++)
> +			arg->args[i] = (id_off + be32_to_cpu(out_base[i]));
> +
> +		arg->args_count = cells;
>  
>  		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
> -			np, map_name, map_mask, id_base, out_base,
> -			id_len, id, masked_id - id_base + out_base);
> +			 np, map_name, map_mask, id_base, be32_to_cpup(out_base),
> +			 id_len, id, id_off + be32_to_cpup(out_base));

Again, having whitespace changes doesn't simplify reviewing.

>  		return 0;
>  	}
>  
> @@ -2198,5 +2263,9 @@ int of_map_id(const struct device_node *np, u32 id,
>  	/* Bypasses translation */
>  	arg->args[0] = id;
>  	return 0;
> +
> +err_map_len:
> +	pr_err("%pOF: Error: Bad %s length: %d\n", np, map_name, map_bytes);
> +	return -EINVAL;
>  }
>  EXPORT_SYMBOL_GPL(of_map_id);

-- 
With best wishes
Dmitry

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Dmitry Baryshkov]

On Sun, Mar 01, 2026 at 10:02:49AM +0000, Marc Zyngier wrote:
> On Sun, 01 Mar 2026 08:34:20 +0000,
> Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> > 
> > From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > 
> > Change of_map_id() to take a pointer to struct of_phandle_args
> > instead of passing target device node and translated IDs separately.
> > Update all callers accordingly.
> > 
> > Subsequent patch will make use of the args_count field in
> > struct of_phandle_args.
> > 
> > Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> > Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> > ---
> >  drivers/iommu/of_iommu.c              |  2 +-
> >  drivers/of/base.c                     | 37 +++++++++++++++++------------------
> >  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
> >  drivers/pci/controller/pcie-apple.c   |  4 +++-
> >  drivers/xen/grant-dma-ops.c           |  2 +-
> >  include/linux/of.h                    | 21 +++++++++++++-------
> >  6 files changed, 44 insertions(+), 30 deletions(-)
> > 
> > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> > index a511ecf21fcd..d255d0f58e8c 100644
> > --- a/drivers/iommu/of_iommu.c
> > +++ b/drivers/iommu/of_iommu.c
> > @@ -48,7 +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_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
> > +	err = of_map_iommu_id(master_np, *id, &iommu_spec);
> >  	if (err)
> >  		return err;
> >  
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index 57420806c1a2..6c3628255908 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -2102,8 +2102,11 @@ int of_find_last_cache_level(unsigned int cpu)
> >   * @id: device ID to map.
> >   * @map_name: property name of the map to use.
> >   * @map_mask_name: optional property name of the mask to use.
> > - * @target: optional pointer to a target device node.
> > - * @id_out: optional pointer to receive the translated ID.
> > + * @arg: of_phandle_args structure,
> > + *	which includes:
> > + *	np: pointer to the target device node
> > + *	args_count: number of arguments
> 
> Number of arguments *to what*? Isn't that the size of args[] instead?

It is a number of values corresponding to the phandle in the DT
property. It might be not obvious here for iommu-maps, but the struct is
idiomatic in OF world. Let me quote a (trimmed) example from
qcom/sm8650.dtsi (for a different property, but it explains the meaning
of the values here):

gem_noc: interconnect@24100000 {
	#interconnect-cells = <2>;
};

epss_l3: interconnect@17d90000 {
	#interconnect-cells = <1>;
};

interconnects = <&gem_noc MASTER_APPSS_PROC QCOM_ICC_TAG_ACTIVE_ONLY
		 &gem_noc SLAVE_LLCC QCOM_ICC_TAG_ACTIVE_ONLY>,
		<&epss_l3 MASTER_EPSS_L3_APPS
		 &epss_l3 SLAVE_EPSS_L3_SHARED>;
/* I skipped the second pair, it adds nothing here */

Here the parsing function for this property (of_icc_get_by_index()) will
call of_parse_phandle_with_args() 4 times and it expects to return the
following values in the of_phandle_args:

1. { .np = gem_noc, .args_count = 2, .args = [MASTER_APPSS_PROC,
                                              QCOM_ICC_TAG_ACTIVE_ONLY] }
2. { .np = gem_noc, .args_count = 2, .args = [SLAVE_LLCC,
                                              QCOM_ICC_TAG_ACTIVE_ONLY] }
3. { .np = epss_l3, .args_count = 1, .args = [MASTER_EPSS_L3_APPS] }
4. { .np = epss_l3, .args_count = 1, .args = [SLAVE_EPSS_L3_SHARED] }

The whole of_phandle_args is then typically passed to the corresponding
xlate function, specific to the paricular .np ('provider'), which will
use #args_count values from the #args array to return the object from
the provider.

Now let's see iommu-maps (again, qcom/sm8650.dtsi):

apps_smmu: iommu@15000000 {
	#iommu-cells = <2>;
};

iommu-map = <0     &apps_smmu 0x1400 0x1>,
	    <0x100 &apps_smmu 0x1401 0x1>;

The property matches current definition at [1], however this spec
doesn't match the DT practice. It forces that the property should use 1
cell for identifying the "object" in the IOMMU provider, even if the
provider expects to use 2 cells (two args).

The correct property should look like:

iommu-map = <0     &apps_smmu 0x1400 0x0 0x1>,
	    <0x100 &apps_smmu 0x1401 0x0 0x1>;

[1] https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/pci/pci-iommu.yaml

> 
> > + *	args[]: array to receive the translated ID(s).
> >   *
> >   * Given a device ID, look up the appropriate implementation-defined
> >   * platform ID and/or the target device which receives transactions on that
> > @@ -2117,21 +2120,21 @@ int of_find_last_cache_level(unsigned int cpu)
> >   */
> >  int of_map_id(const struct device_node *np, u32 id,
> >  	       const char *map_name, const char *map_mask_name,
> > -	       struct device_node **target, u32 *id_out)
> > +	       struct of_phandle_args *arg)
> >  {
> >  	u32 map_mask, masked_id;
> >  	int map_len;
> >  	const __be32 *map = NULL;
> >  
> > -	if (!np || !map_name || (!target && !id_out))
> > +	if (!np || !map_name || !arg)
> >  		return -EINVAL;
> >  
> >  	map = of_get_property(np, map_name, &map_len);
> >  	if (!map) {
> > -		if (target)
> > +		if (arg->np)
> >  			return -ENODEV;
> >  		/* Otherwise, no map implies no translation */
> > -		*id_out = id;
> > +		arg->args[0] = id;
> 
> What if args_count is 0? Given that you place no restriction on the
> way this can be called, that'd be entirely legitimate, and you'd
> corrupt something you're not supposed to touch.

args is an array (not a pointer) in of_phandle_args. As such we know
that args[0] is legit.

> 
> >  		return 0;
> >  	}
> >  
> > @@ -2173,18 +2176,15 @@ int of_map_id(const struct device_node *np, u32 id,
> >  		if (!phandle_node)
> >  			return -ENODEV;
> >  
> > -		if (target) {
> > -			if (*target)
> > -				of_node_put(phandle_node);
> > -			else
> > -				*target = phandle_node;
> > +		if (arg->np)
> > +			of_node_put(phandle_node);
> > +		else
> > +			arg->np = phandle_node;
> >  
> > -			if (*target != phandle_node)
> > -				continue;
> > -		}
> > +		if (arg->np != phandle_node)
> > +			continue;
> >  
> > -		if (id_out)
> > -			*id_out = masked_id - id_base + out_base;
> > +		arg->args[0] = masked_id - id_base + out_base;
> >  
> >  		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
> >  			np, map_name, map_mask, id_base, out_base,
> > @@ -2193,11 +2193,10 @@ int of_map_id(const struct device_node *np, u32 id,
> >  	}
> >  
> >  	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
> > -		id, target && *target ? *target : NULL);
> > +		id, arg->np ? arg->np : NULL);
> >  
> >  	/* Bypasses translation */
> > -	if (id_out)
> > -		*id_out = id;
> > +	arg->args[0] = id;
> >  	return 0;
> >  }
> >  EXPORT_SYMBOL_GPL(of_map_id);
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index bff8289f804a..74fc603b3f84 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -1139,12 +1139,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
> >  {
> >  	struct device *dev = imx_pcie->pci->dev;
> >  	struct device_node *target;
> > +	struct of_phandle_args iommu_spec = { .args_count = 1 };
> >  	u32 sid_i, sid_m;
> >  	int err_i, err_m;
> >  	u32 sid = 0;
> >  
> >  	target = NULL;
> > -	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
> > +	err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec);
> > +	if (!err_i) {
> > +		target = iommu_spec.np;
> > +		sid_i = iommu_spec.args[0];
> > +	}
> > +
> >  	if (target) {
> >  		of_node_put(target);
> >  	} else {
> > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> > index a0937b7b3c4d..e1d4b37d200d 100644
> > --- a/drivers/pci/controller/pcie-apple.c
> > +++ b/drivers/pci/controller/pcie-apple.c
> > @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
> >  {
> >  	u32 sid, rid = pci_dev_id(pdev);
> >  	struct apple_pcie_port *port;
> > +	struct of_phandle_args iommu_spec = { .args_count = 1 };
> >  	int idx, err;
> >  
> >  	port = apple_pcie_get_port(pdev);
> > @@ -764,10 +765,11 @@ 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_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
> > +	err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec);
> >  	if (err)
> >  		return err;
> >  
> > +	sid = iommu_spec.args[0];
> 
> I find this stuff absolutely unreadable. You're fishing the SID in a
> random position of a random structure, without any documentation of
> how this is supposed to work. This really needs a wrapper that hides
> this implementation detail.
> 
> Thanks,
> 
> 	M.
> 
> -- 
> Without deviation from the norm, progress is not possible.

-- 
With best wishes
Dmitry

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Dmitry Baryshkov]

On Sun, Mar 01, 2026 at 02:04:20PM +0530, Vijayanand Jitta wrote:
> From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> 
> Change of_map_id() to take a pointer to struct of_phandle_args
> instead of passing target device node and translated IDs separately.
> Update all callers accordingly.
> 
> Subsequent patch will make use of the args_count field in
> struct of_phandle_args.
> 
> Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> ---
>  drivers/iommu/of_iommu.c              |  2 +-
>  drivers/of/base.c                     | 37 +++++++++++++++++------------------
>  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
>  drivers/pci/controller/pcie-apple.c   |  4 +++-
>  drivers/xen/grant-dma-ops.c           |  2 +-
>  include/linux/of.h                    | 21 +++++++++++++-------
>  6 files changed, 44 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index a0937b7b3c4d..e1d4b37d200d 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
>  {
>  	u32 sid, rid = pci_dev_id(pdev);
>  	struct apple_pcie_port *port;
> +	struct of_phandle_args iommu_spec = { .args_count = 1 };

Hmm, I didn't notice this. Parsing functions are expected to ignore
of_phandle_args before the parsing. So passing .args_count = 1 is
strange.

>  	int idx, err;
>  
>  	port = apple_pcie_get_port(pdev);

-- 
With best wishes
Dmitry

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Marc Zyngier]

On Sun, 01 Mar 2026 10:46:57 +0000,
Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> wrote:
> 
> On Sun, Mar 01, 2026 at 10:02:49AM +0000, Marc Zyngier wrote:
> > On Sun, 01 Mar 2026 08:34:20 +0000,
> > Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> > > 
> > > From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > > 
> > > Change of_map_id() to take a pointer to struct of_phandle_args
> > > instead of passing target device node and translated IDs separately.
> > > Update all callers accordingly.
> > > 
> > > Subsequent patch will make use of the args_count field in
> > > struct of_phandle_args.
> > > 
> > > Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> > > Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > > Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> > > ---
> > >  drivers/iommu/of_iommu.c              |  2 +-
> > >  drivers/of/base.c                     | 37 +++++++++++++++++------------------
> > >  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
> > >  drivers/pci/controller/pcie-apple.c   |  4 +++-
> > >  drivers/xen/grant-dma-ops.c           |  2 +-
> > >  include/linux/of.h                    | 21 +++++++++++++-------
> > >  6 files changed, 44 insertions(+), 30 deletions(-)
> > > 
> > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> > > index a511ecf21fcd..d255d0f58e8c 100644
> > > --- a/drivers/iommu/of_iommu.c
> > > +++ b/drivers/iommu/of_iommu.c
> > > @@ -48,7 +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_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
> > > +	err = of_map_iommu_id(master_np, *id, &iommu_spec);
> > >  	if (err)
> > >  		return err;
> > >  
> > > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > > index 57420806c1a2..6c3628255908 100644
> > > --- a/drivers/of/base.c
> > > +++ b/drivers/of/base.c
> > > @@ -2102,8 +2102,11 @@ int of_find_last_cache_level(unsigned int cpu)
> > >   * @id: device ID to map.
> > >   * @map_name: property name of the map to use.
> > >   * @map_mask_name: optional property name of the mask to use.
> > > - * @target: optional pointer to a target device node.
> > > - * @id_out: optional pointer to receive the translated ID.
> > > + * @arg: of_phandle_args structure,
> > > + *	which includes:
> > > + *	np: pointer to the target device node
> > > + *	args_count: number of arguments
> > 
> > Number of arguments *to what*? Isn't that the size of args[] instead?
> 
> It is a number of values corresponding to the phandle in the DT
> property.

No. It is what the *caller* expects. Not what is is in the DT, which
could be (and generally is) a pile of random crap. If the two don't
match, return an error. But don't randomly overwrite data that is not
yours.

[...]

> It might be not obvious here for iommu-maps, but the struct is
> idiomatic in OF world. Let me quote a (trimmed) example from
> qcom/sm8650.dtsi (for a different property, but it explains the meaning
> of the values here):
> 
> gem_noc: interconnect@24100000 {
> 	#interconnect-cells = <2>;
> };
> 
> epss_l3: interconnect@17d90000 {
> 	#interconnect-cells = <1>;
> };
> 
> interconnects = <&gem_noc MASTER_APPSS_PROC QCOM_ICC_TAG_ACTIVE_ONLY
> 		 &gem_noc SLAVE_LLCC QCOM_ICC_TAG_ACTIVE_ONLY>,
> 		<&epss_l3 MASTER_EPSS_L3_APPS
> 		 &epss_l3 SLAVE_EPSS_L3_SHARED>;
> /* I skipped the second pair, it adds nothing here */
> 
> Here the parsing function for this property (of_icc_get_by_index()) will
> call of_parse_phandle_with_args() 4 times and it expects to return the
> following values in the of_phandle_args:
> 
> 1. { .np = gem_noc, .args_count = 2, .args = [MASTER_APPSS_PROC,
>                                               QCOM_ICC_TAG_ACTIVE_ONLY] }
> 2. { .np = gem_noc, .args_count = 2, .args = [SLAVE_LLCC,
>                                               QCOM_ICC_TAG_ACTIVE_ONLY] }
> 3. { .np = epss_l3, .args_count = 1, .args = [MASTER_EPSS_L3_APPS] }
> 4. { .np = epss_l3, .args_count = 1, .args = [SLAVE_EPSS_L3_SHARED] }
> 
> The whole of_phandle_args is then typically passed to the corresponding
> xlate function, specific to the paricular .np ('provider'), which will
> use #args_count values from the #args array to return the object from
> the provider.
> 
> Now let's see iommu-maps (again, qcom/sm8650.dtsi):
> 
> apps_smmu: iommu@15000000 {
> 	#iommu-cells = <2>;
> };
> 
> iommu-map = <0     &apps_smmu 0x1400 0x1>,
> 	    <0x100 &apps_smmu 0x1401 0x1>;
> 
> The property matches current definition at [1], however this spec
> doesn't match the DT practice. It forces that the property should use 1
> cell for identifying the "object" in the IOMMU provider, even if the
> provider expects to use 2 cells (two args).
> 
> The correct property should look like:
> 
> iommu-map = <0     &apps_smmu 0x1400 0x0 0x1>,
> 	    <0x100 &apps_smmu 0x1401 0x0 0x1>;
> 
> [1] https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/pci/pci-iommu.yaml
> 
> > 
> > > + *	args[]: array to receive the translated ID(s).
> > >   *
> > >   * Given a device ID, look up the appropriate implementation-defined
> > >   * platform ID and/or the target device which receives transactions on that
> > > @@ -2117,21 +2120,21 @@ int of_find_last_cache_level(unsigned int cpu)
> > >   */
> > >  int of_map_id(const struct device_node *np, u32 id,
> > >  	       const char *map_name, const char *map_mask_name,
> > > -	       struct device_node **target, u32 *id_out)
> > > +	       struct of_phandle_args *arg)
> > >  {
> > >  	u32 map_mask, masked_id;
> > >  	int map_len;
> > >  	const __be32 *map = NULL;
> > >  
> > > -	if (!np || !map_name || (!target && !id_out))
> > > +	if (!np || !map_name || !arg)
> > >  		return -EINVAL;
> > >  
> > >  	map = of_get_property(np, map_name, &map_len);
> > >  	if (!map) {
> > > -		if (target)
> > > +		if (arg->np)
> > >  			return -ENODEV;
> > >  		/* Otherwise, no map implies no translation */
> > > -		*id_out = id;
> > > +		arg->args[0] = id;
> > 
> > What if args_count is 0? Given that you place no restriction on the
> > way this can be called, that'd be entirely legitimate, and you'd
> > corrupt something you're not supposed to touch.
> 
> args is an array (not a pointer) in of_phandle_args. As such we know
> that args[0] is legit.

Again, no. The caller is telling you what it expects. This is strictly
equivalent to:

	void func(void *blah[], int sz);

func() is not supposed to look beyond sz. As it stands, this change in
not acceptable.

	M.

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

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Marc Zyngier]

On Sun, 01 Mar 2026 10:59:23 +0000,
Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> wrote:
> 
> On Sun, Mar 01, 2026 at 02:04:20PM +0530, Vijayanand Jitta wrote:
> > From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > 
> > Change of_map_id() to take a pointer to struct of_phandle_args
> > instead of passing target device node and translated IDs separately.
> > Update all callers accordingly.
> > 
> > Subsequent patch will make use of the args_count field in
> > struct of_phandle_args.
> > 
> > Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> > Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> > ---
> >  drivers/iommu/of_iommu.c              |  2 +-
> >  drivers/of/base.c                     | 37 +++++++++++++++++------------------
> >  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
> >  drivers/pci/controller/pcie-apple.c   |  4 +++-
> >  drivers/xen/grant-dma-ops.c           |  2 +-
> >  include/linux/of.h                    | 21 +++++++++++++-------
> >  6 files changed, 44 insertions(+), 30 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> > index a0937b7b3c4d..e1d4b37d200d 100644
> > --- a/drivers/pci/controller/pcie-apple.c
> > +++ b/drivers/pci/controller/pcie-apple.c
> > @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
> >  {
> >  	u32 sid, rid = pci_dev_id(pdev);
> >  	struct apple_pcie_port *port;
> > +	struct of_phandle_args iommu_spec = { .args_count = 1 };
> 
> Hmm, I didn't notice this. Parsing functions are expected to ignore
> of_phandle_args before the parsing. So passing .args_count = 1 is
> strange.

It isn't strange. It is a semantic requirement. It explicitly
indicates the boundary of what the driver is prepared to receive, just
like passing a single u32 * is perfectly clear.

Frankly, this patch makes an absolute mess of the current API.

	M.

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

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Dmitry Baryshkov]

On Sun, Mar 01, 2026 at 11:42:47AM +0000, Marc Zyngier wrote:
> On Sun, 01 Mar 2026 10:46:57 +0000,
> Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> wrote:
> > 
> > On Sun, Mar 01, 2026 at 10:02:49AM +0000, Marc Zyngier wrote:
> > > On Sun, 01 Mar 2026 08:34:20 +0000,
> > > Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> > > > 
> > > > From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > > > 
> > > > Change of_map_id() to take a pointer to struct of_phandle_args
> > > > instead of passing target device node and translated IDs separately.
> > > > Update all callers accordingly.
> > > > 
> > > > Subsequent patch will make use of the args_count field in
> > > > struct of_phandle_args.
> > > > 
> > > > Suggested-by: Rob Herring (Arm) <robh@kernel.org>
> > > > Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
> > > > Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> > > > ---
> > > >  drivers/iommu/of_iommu.c              |  2 +-
> > > >  drivers/of/base.c                     | 37 +++++++++++++++++------------------
> > > >  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
> > > >  drivers/pci/controller/pcie-apple.c   |  4 +++-
> > > >  drivers/xen/grant-dma-ops.c           |  2 +-
> > > >  include/linux/of.h                    | 21 +++++++++++++-------
> > > >  6 files changed, 44 insertions(+), 30 deletions(-)
> > > > 
> > > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> > > > index a511ecf21fcd..d255d0f58e8c 100644
> > > > --- a/drivers/iommu/of_iommu.c
> > > > +++ b/drivers/iommu/of_iommu.c
> > > > @@ -48,7 +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_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
> > > > +	err = of_map_iommu_id(master_np, *id, &iommu_spec);
> > > >  	if (err)
> > > >  		return err;
> > > >  
> > > > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > > > index 57420806c1a2..6c3628255908 100644
> > > > --- a/drivers/of/base.c
> > > > +++ b/drivers/of/base.c
> > > > @@ -2102,8 +2102,11 @@ int of_find_last_cache_level(unsigned int cpu)
> > > >   * @id: device ID to map.
> > > >   * @map_name: property name of the map to use.
> > > >   * @map_mask_name: optional property name of the mask to use.
> > > > - * @target: optional pointer to a target device node.
> > > > - * @id_out: optional pointer to receive the translated ID.
> > > > + * @arg: of_phandle_args structure,
> > > > + *	which includes:
> > > > + *	np: pointer to the target device node
> > > > + *	args_count: number of arguments
> > > 
> > > Number of arguments *to what*? Isn't that the size of args[] instead?
> > 
> > It is a number of values corresponding to the phandle in the DT
> > property.
> 
> No. It is what the *caller* expects. Not what is is in the DT, which
> could be (and generally is) a pile of random crap.

Nice

> If the two don't
> match, return an error. But don't randomly overwrite data that is not
> yours.

Mark, no. The caller can't know how many cell arguments the provider
uses until:
- the provider handle is parsed
- provider node is consulted for the #foo-cells

It is not a number of arguments for the _caller_. It is how many u32
values are used by the _provider_.

In case of IOMMUs, enough IOMMU devices have #iommu-cells = <2>, which
means that it uses two u32 values to identify the SID or set of SIDs.

Following your analogy, if we force 1 cell in the iommu-map property, we
are trying to force the function which expects to take two arguments to
accept just one. But it's not the caller, it's the IOMMU's xlate
function.


> 
> [...]
> 
> > It might be not obvious here for iommu-maps, but the struct is
> > idiomatic in OF world. Let me quote a (trimmed) example from
> > qcom/sm8650.dtsi (for a different property, but it explains the meaning
> > of the values here):
> > 
> > gem_noc: interconnect@24100000 {
> > 	#interconnect-cells = <2>;
> > };
> > 
> > epss_l3: interconnect@17d90000 {
> > 	#interconnect-cells = <1>;
> > };
> > 
> > interconnects = <&gem_noc MASTER_APPSS_PROC QCOM_ICC_TAG_ACTIVE_ONLY
> > 		 &gem_noc SLAVE_LLCC QCOM_ICC_TAG_ACTIVE_ONLY>,
> > 		<&epss_l3 MASTER_EPSS_L3_APPS
> > 		 &epss_l3 SLAVE_EPSS_L3_SHARED>;
> > /* I skipped the second pair, it adds nothing here */
> > 
> > Here the parsing function for this property (of_icc_get_by_index()) will
> > call of_parse_phandle_with_args() 4 times and it expects to return the
> > following values in the of_phandle_args:
> > 
> > 1. { .np = gem_noc, .args_count = 2, .args = [MASTER_APPSS_PROC,
> >                                               QCOM_ICC_TAG_ACTIVE_ONLY] }
> > 2. { .np = gem_noc, .args_count = 2, .args = [SLAVE_LLCC,
> >                                               QCOM_ICC_TAG_ACTIVE_ONLY] }
> > 3. { .np = epss_l3, .args_count = 1, .args = [MASTER_EPSS_L3_APPS] }
> > 4. { .np = epss_l3, .args_count = 1, .args = [SLAVE_EPSS_L3_SHARED] }
> > 
> > The whole of_phandle_args is then typically passed to the corresponding
> > xlate function, specific to the paricular .np ('provider'), which will
> > use #args_count values from the #args array to return the object from
> > the provider.
> > 
> > Now let's see iommu-maps (again, qcom/sm8650.dtsi):
> > 
> > apps_smmu: iommu@15000000 {
> > 	#iommu-cells = <2>;
> > };
> > 
> > iommu-map = <0     &apps_smmu 0x1400 0x1>,
> > 	    <0x100 &apps_smmu 0x1401 0x1>;
> > 
> > The property matches current definition at [1], however this spec
> > doesn't match the DT practice. It forces that the property should use 1
> > cell for identifying the "object" in the IOMMU provider, even if the
> > provider expects to use 2 cells (two args).
> > 
> > The correct property should look like:
> > 
> > iommu-map = <0     &apps_smmu 0x1400 0x0 0x1>,
> > 	    <0x100 &apps_smmu 0x1401 0x0 0x1>;
> > 
> > [1] https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/pci/pci-iommu.yaml
> > 
> > > 
> > > > + *	args[]: array to receive the translated ID(s).
> > > >   *
> > > >   * Given a device ID, look up the appropriate implementation-defined
> > > >   * platform ID and/or the target device which receives transactions on that
> > > > @@ -2117,21 +2120,21 @@ int of_find_last_cache_level(unsigned int cpu)
> > > >   */
> > > >  int of_map_id(const struct device_node *np, u32 id,
> > > >  	       const char *map_name, const char *map_mask_name,
> > > > -	       struct device_node **target, u32 *id_out)
> > > > +	       struct of_phandle_args *arg)
> > > >  {
> > > >  	u32 map_mask, masked_id;
> > > >  	int map_len;
> > > >  	const __be32 *map = NULL;
> > > >  
> > > > -	if (!np || !map_name || (!target && !id_out))
> > > > +	if (!np || !map_name || !arg)
> > > >  		return -EINVAL;
> > > >  
> > > >  	map = of_get_property(np, map_name, &map_len);
> > > >  	if (!map) {
> > > > -		if (target)
> > > > +		if (arg->np)
> > > >  			return -ENODEV;
> > > >  		/* Otherwise, no map implies no translation */
> > > > -		*id_out = id;
> > > > +		arg->args[0] = id;
> > > 
> > > What if args_count is 0? Given that you place no restriction on the
> > > way this can be called, that'd be entirely legitimate, and you'd
> > > corrupt something you're not supposed to touch.
> > 
> > args is an array (not a pointer) in of_phandle_args. As such we know
> > that args[0] is legit.
> 
> Again, no. The caller is telling you what it expects. This is strictly
> equivalent to:
> 
> 	void func(void *blah[], int sz);
> 
> func() is not supposed to look beyond sz. As it stands, this change in
> not acceptable.

DT parsing functions follow a different approach, because of the "random
crap". It is:

    int parse(void *phandle, u32 **args, int *sz);

So, if the caller insists that it can handle only one argument, it
should call parse(), then check that (sz == 1) and return -EINVAL
otherwise (kfreeing *args and of_node_puting phandle while it does so).

I will quote of_phandle_args here:

struct of_phandle_args {
        struct device_node *np;
        int args_count;
        uint32_t args[MAX_PHANDLE_ARGS];
};


Please take a look at how of_parse_phandle_with_args() works.

-- 
With best wishes
Dmitry

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

[Vijayanand Jitta]

On 3/1/2026 3:16 PM, Marc Zyngier wrote:
> On Sun, 01 Mar 2026 08:34:19 +0000,
> Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
>>
>> From: Robin Murphy <robin.murphy@arm.com>
>>
>> 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@kernel.org>
>> Reviewed-by: Frank Li <Frank.Li@nxp.com>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
>> ---
>>  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@kernel.org>
> 
> 	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

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Vijayanand Jitta]

On 3/1/2026 3:32 PM, Dmitry Baryshkov wrote:
> On Sun, Mar 01, 2026 at 02:04:20PM +0530, Vijayanand Jitta wrote:
>> From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
>>
>> Change of_map_id() to take a pointer to struct of_phandle_args
>> instead of passing target device node and translated IDs separately.
>> Update all callers accordingly.
>>
>> Subsequent patch will make use of the args_count field in
>> struct of_phandle_args.
>>
>> Suggested-by: Rob Herring (Arm) <robh@kernel.org>
>> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
>> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
>> ---
>>  drivers/iommu/of_iommu.c              |  2 +-
>>  drivers/of/base.c                     | 37 +++++++++++++++++------------------
>>  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
>>  drivers/pci/controller/pcie-apple.c   |  4 +++-
>>  drivers/xen/grant-dma-ops.c           |  2 +-
>>  include/linux/of.h                    | 21 +++++++++++++-------
>>  6 files changed, 44 insertions(+), 30 deletions(-)
>>
> 
>> @@ -2193,11 +2193,10 @@ int of_map_id(const struct device_node *np, u32 id,
>>  	}
>>  
>>  	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
>> -		id, target && *target ? *target : NULL);
>> +		id, arg->np ? arg->np : NULL);
> 
> Is it just 'args->np' then? If it's NULL, it's NULL anyway.
> 
Right, will update this.

>>  
>>  	/* Bypasses translation */
>> -	if (id_out)
>> -		*id_out = id;
>> +	arg->args[0] = id;
>>  	return 0;
>>  }
>>  EXPORT_SYMBOL_GPL(of_map_id);
>> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
>> index bff8289f804a..74fc603b3f84 100644
>> --- a/drivers/pci/controller/dwc/pci-imx6.c
>> +++ b/drivers/pci/controller/dwc/pci-imx6.c
>> @@ -1139,12 +1139,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
>>  {
>>  	struct device *dev = imx_pcie->pci->dev;
>>  	struct device_node *target;
>> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
>>  	u32 sid_i, sid_m;
>>  	int err_i, err_m;
>>  	u32 sid = 0;
>>  
>>  	target = NULL;
>> -	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
>> +	err_i = of_map_iommu_id(dev->of_node, rid, &iommu_spec);
>> +	if (!err_i) {
>> +		target = iommu_spec.np;
>> +		sid_i = iommu_spec.args[0];
>> +	}
>> +
>>  	if (target) {
>>  		of_node_put(target);
>>  	} else {
>> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
>> index a0937b7b3c4d..e1d4b37d200d 100644
>> --- a/drivers/pci/controller/pcie-apple.c
>> +++ b/drivers/pci/controller/pcie-apple.c
>> @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
>>  {
>>  	u32 sid, rid = pci_dev_id(pdev);
>>  	struct apple_pcie_port *port;
>> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
>>  	int idx, err;
>>  
>>  	port = apple_pcie_get_port(pdev);
>> @@ -764,10 +765,11 @@ 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_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
>> +	err = of_map_iommu_id(port->pcie->dev->of_node, rid, &iommu_spec);
>>  	if (err)
>>  		return err;
> 
> of_node_put(iommu_spec.np);
> 

Sure, will add this.

>>  
>> +	sid = iommu_spec.args[0];
>>  	mutex_lock(&port->pcie->lock);
>>  
>>  	idx = bitmap_find_free_region(port->sid_map, port->sid_map_sz, 0);
>> diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
>> index 1b7696b2d762..5f1d6540049a 100644
>> --- a/drivers/xen/grant-dma-ops.c
>> +++ b/drivers/xen/grant-dma-ops.c
>> @@ -325,7 +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_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
>> +		if (of_map_iommu_id(np, rid, &iommu_spec)) {
>>  			dev_dbg(dev, "Cannot translate ID\n");
>>  			return -ESRCH;
>>  		}
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 824649867810..9d72d76f909d 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -463,7 +463,7 @@ bool of_console_check(const struct device_node *dn, char *name, int index);
>>  
>>  int of_map_id(const struct device_node *np, u32 id,
>>  	       const char *map_name, const char *map_mask_name,
>> -	       struct device_node **target, u32 *id_out);
>> +	       struct of_phandle_args *arg);
>>  
>>  phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
>>  
>> @@ -929,7 +929,7 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
>>  
>>  static inline int of_map_id(const struct device_node *np, u32 id,
>>  			     const char *map_name, const char *map_mask_name,
>> -			     struct device_node **target, u32 *id_out)
>> +			     struct of_phandle_args *arg)
>>  {
>>  	return -EINVAL;
>>  }
>> @@ -1458,17 +1458,24 @@ static inline int of_property_read_s32(const struct device_node *np,
>>  }
>>  
>>  static inline int of_map_iommu_id(const struct device_node *np, u32 id,
>> -				  struct device_node **target, u32 *id_out)
>> +				  struct of_phandle_args *arg)
> 
> Document that it's the caller's responsibility to of_node_put() returned
> node. As it can be seen from the previous comment, it's not obvious.
> 

Sure, will add comment regarding this.

>>  {
>> -	return of_map_id(np, id, "iommu-map", "iommu-map-mask",
>> -			 target, id_out);
>> +	return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
>>  }
>>  
>>  static inline int of_map_msi_id(const struct device_node *np, u32 id,
>>  				struct device_node **target, u32 *id_out)
> 
> Is there a reason for chaning the of_map_iommu_id() args but not
> of_map_msi_id() args?
> 
 
Thanks for pointing this out. I’ll update the series to keep of_map_iommu_id()
and of_map_msi_id() aligned.

>>  {
>> -	return of_map_id(np, id, "msi-map", "msi-map-mask",
>> -			 target, id_out);
>> +	struct of_phandle_args msi_spec = { .np = *target, .args_count = 1 };
> 
> Which driver passes something being worth of storing in .np?
> 

You're right, There is no need to store these input args. Will remove these initializations.

Thanks,
Vijay

>> +	int ret;
>> +
>> +	ret = of_map_id(np, id, "msi-map", "msi-map-mask", &msi_spec);
>> +	if (!ret) {
>> +		*target = msi_spec.np;
>> +		*id_out = msi_spec.args[0];
>> +	}
>> +
>> +	return ret;
>>  }
>>  
>>  #define of_for_each_phandle(it, err, np, ln, cn, cc)			\
>>
>> -- 
>> 2.34.1
>>
> 

Re: [PATCH v9 2/3] of: factor arguments passed to of_map_id() into a struct

[Vijayanand Jitta]

On 3/1/2026 4:29 PM, Dmitry Baryshkov wrote:
> On Sun, Mar 01, 2026 at 02:04:20PM +0530, Vijayanand Jitta wrote:
>> From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
>>
>> Change of_map_id() to take a pointer to struct of_phandle_args
>> instead of passing target device node and translated IDs separately.
>> Update all callers accordingly.
>>
>> Subsequent patch will make use of the args_count field in
>> struct of_phandle_args.
>>
>> Suggested-by: Rob Herring (Arm) <robh@kernel.org>
>> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
>> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
>> ---
>>  drivers/iommu/of_iommu.c              |  2 +-
>>  drivers/of/base.c                     | 37 +++++++++++++++++------------------
>>  drivers/pci/controller/dwc/pci-imx6.c |  8 +++++++-
>>  drivers/pci/controller/pcie-apple.c   |  4 +++-
>>  drivers/xen/grant-dma-ops.c           |  2 +-
>>  include/linux/of.h                    | 21 +++++++++++++-------
>>  6 files changed, 44 insertions(+), 30 deletions(-)
>>
>> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
>> index a0937b7b3c4d..e1d4b37d200d 100644
>> --- a/drivers/pci/controller/pcie-apple.c
>> +++ b/drivers/pci/controller/pcie-apple.c
>> @@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
>>  {
>>  	u32 sid, rid = pci_dev_id(pdev);
>>  	struct apple_pcie_port *port;
>> +	struct of_phandle_args iommu_spec = { .args_count = 1 };
> 
> Hmm, I didn't notice this. Parsing functions are expected to ignore
> of_phandle_args before the parsing. So passing .args_count = 1 is
> strange.
> 

You're right, This is not required. I'll remove these initializations in next 
series.

Thanks,
Vijay

>>  	int idx, err;
>>  
>>  	port = apple_pcie_get_port(pdev);
> 

Re: [PATCH v9 3/3] of: Respect #{iommu,msi}-cells in maps

[Vijayanand Jitta]

On 3/1/2026 3:44 PM, Dmitry Baryshkov wrote:
> On Sun, Mar 01, 2026 at 02:04:21PM +0530, Vijayanand Jitta wrote:
>> From: Robin Murphy <robin.murphy@arm.com>
>>
>> So far our parsing of {iommu,msi}-map properites has always blindly
>> assumed that the output specifiers will always have exactly 1 cell.
>> This typically does happen to be the case, but is not actually enforced
>> (and the PCI msi-map binding even explicitly states support for 0 or 1
>> cells) - as a result we've now ended up with dodgy DTs out in the field
>> which depend on this behaviour to map a 1-cell specifier for a 2-cell
>> provider, despite that being bogus per the bindings themselves.
>>
>> Since there is some potential use in being able to map at least single
>> input IDs to multi-cell output specifiers (and properly support 0-cell
>> outputs as well), add support for properly parsing and using the target
>> nodes' #cells values, albeit with the unfortunate complication of still
>> having to work around expectations of the old behaviour too.
>>
>> Since there are multi-cell output specifiers, the callers of of_map_id()
>> may need to get the exact cell output value for further processing.
>> Added support for that part --charan
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
>> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
>> ---
>>  drivers/iommu/of_iommu.c |   2 +-
>>  drivers/of/base.c        | 117 +++++++++++++++++++++++++++++++++++++----------
>>  include/linux/of.h       |  16 +++----
>>  3 files changed, 102 insertions(+), 33 deletions(-)
>>
> 
>>  /**
>>   * of_map_id - Translate an ID through a downstream mapping.
>>   * @np: root complex device node.
>>   * @id: device ID to map.
>>   * @map_name: property name of the map to use.
>> + * @cells_name: property name of target specifier cells.
>>   * @map_mask_name: optional property name of the mask to use.
>>   * @arg: of_phandle_args structure,
>>   *	which includes:
>> @@ -2118,18 +2145,19 @@ int of_find_last_cache_level(unsigned int cpu)
>>   *
>>   * Return: 0 on success or a standard error code on failure.
>>   */
>> -int of_map_id(const struct device_node *np, u32 id,
>> -	       const char *map_name, const char *map_mask_name,
>> -	       struct of_phandle_args *arg)
>> +int of_map_id(const struct device_node *np, u32 id, const char *map_name,
>> +	      const char *cells_name, const char *map_mask_name,
>> +	      struct of_phandle_args *arg)
> 
> Some extra whitespace-related noise in here. Last line wasn't changed,
> so there is no need to touch it.
> 

Thanks for pointing this, Will fix it in next series.

>>  {
>>  	u32 map_mask, masked_id;
>> -	int map_len;
>> +	int map_bytes, map_len, offset = 0;
>> +	bool bad_map = false;
>>  	const __be32 *map = NULL;
>>  
>>  	if (!np || !map_name || !arg)
>>  		return -EINVAL;
>>  
>> -	map = of_get_property(np, map_name, &map_len);
>> +	map = of_get_property(np, map_name, &map_bytes);
>>  	if (!map) {
>>  		if (arg->np)
>>  			return -ENODEV;
>> @@ -2138,11 +2166,9 @@ int of_map_id(const struct device_node *np, u32 id,
>>  		return 0;
>>  	}
>>  
>> -	if (!map_len || map_len % (4 * sizeof(*map))) {
>> -		pr_err("%pOF: Error: Bad %s length: %d\n", np,
>> -			map_name, map_len);
>> -		return -EINVAL;
>> -	}
>> +	if (map_bytes % sizeof(*map))
>> +		goto err_map_len;
>> +	map_len = map_bytes / sizeof(*map);
>>  
>>  	/* The default is to select all bits. */
>>  	map_mask = 0xffffffff;
>> @@ -2155,27 +2181,63 @@ int of_map_id(const struct device_node *np, u32 id,
>>  		of_property_read_u32(np, map_mask_name, &map_mask);
>>  
>>  	masked_id = map_mask & id;
>> -	for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
>> +
>> +	while (offset < map_len) {
>>  		struct device_node *phandle_node;
>> -		u32 id_base = be32_to_cpup(map + 0);
>> -		u32 phandle = be32_to_cpup(map + 1);
>> -		u32 out_base = be32_to_cpup(map + 2);
>> -		u32 id_len = be32_to_cpup(map + 3);
>> +		u32 id_base, phandle, id_len, id_off, cells = 0;
>> +		const __be32 *out_base;
>> +
>> +		if (map_len - offset < 2)
>> +			goto err_map_len;
>> +
>> +		id_base = be32_to_cpup(map + offset);
>>  
>>  		if (id_base & ~map_mask) {
>> -			pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
>> -				np, map_name, map_name,
>> -				map_mask, id_base);
>> +			pr_err("%pOF: Invalid %s translation - %s (0x%x) ignores id-base (0x%x)\n",
>> +			       np, map_name, map_mask_name, map_mask, id_base);
>>  			return -EFAULT;
>>  		}
>>  
>> -		if (masked_id < id_base || masked_id >= id_base + id_len)
>> -			continue;
>> -
>> +		phandle = be32_to_cpup(map + offset + 1);
>>  		phandle_node = of_find_node_by_phandle(phandle);
>>  		if (!phandle_node)
>>  			return -ENODEV;
>>  
>> +		if (!bad_map && of_property_read_u32(phandle_node, cells_name, &cells)) {
>> +			pr_err("%pOF: missing %s property\n", phandle_node, cells_name);
>> +			return -EINVAL;
>> +		}
> 
> This will trigger the cells_name property check even if later we
> discover that we have a "bad" map. Is it intended / required?
> 

It’s intended. We need the cells value here because determining whether
a map is “bad” depends on it, as mentioned in description of of_check_bad_map
this is specifically for the case where the DT has an iommu-map pointing to
a 2‑cell IOMMU node but only provides 1 cell in the map entry.

>> +
>> +		if (map_len - offset < 3 + cells)
> 
> of_node_put(phandle_node);
> 
>> +			goto err_map_len;
>> +
>> +		if (offset == 0 && cells == 2) {
> 
> ... if it's not required, then the bad_map check can be moved before the
> loop.
> 

Given that, the bad_map check can’t be moved before the loop, because we only
call of_check_bad_map() when cells == 2.

>> +			bad_map = of_check_bad_map(map, map_len);
>> +			if (bad_map) {
>> +				pr_warn_once("%pOF: %s mismatches target %s, assuming extra cell of 0\n",
>> +					     np, map_name, cells_name);
>> +				cells = 1;
>> +			}
>> +		}
>> +
>> +		out_base = map + offset + 2;
>> +		offset += 3 + cells;
>> +
>> +		id_len = be32_to_cpup(map + offset - 1);
>> +		if (id_len > 1 && cells > 1) {
>> +			/*
>> +			 * With 1 output cell we reasonably assume its value
>> +			 * has a linear relationship to the input; with more,
>> +			 * we'd need help from the provider to know what to do.
>> +			 */
>> +			pr_err("%pOF: Unsupported %s - cannot handle %d-ID range with %d-cell output specifier\n",
>> +			       np, map_name, id_len, cells);
>> +			return -EINVAL;
>> +		}
>> +		id_off = masked_id - id_base;
>> +		if (masked_id < id_base || id_off >= id_len)
>> +			continue;
>> +
>>  		if (arg->np)
>>  			of_node_put(phandle_node);
>>  		else
>> @@ -2184,11 +2246,14 @@ int of_map_id(const struct device_node *np, u32 id,
>>  		if (arg->np != phandle_node)
>>  			continue;
>>  
>> -		arg->args[0] = masked_id - id_base + out_base;
>> +		for (int i = 0; i < cells; i++)
>> +			arg->args[i] = (id_off + be32_to_cpu(out_base[i]));
>> +
>> +		arg->args_count = cells;
>>  
>>  		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
>> -			np, map_name, map_mask, id_base, out_base,
>> -			id_len, id, masked_id - id_base + out_base);
>> +			 np, map_name, map_mask, id_base, be32_to_cpup(out_base),
>> +			 id_len, id, id_off + be32_to_cpup(out_base));
> 
> Again, having whitespace changes doesn't simplify reviewing.
> 

Will fix this in next series.

Thanks,
Vijay
>>  		return 0;
>>  	}
>>  
>> @@ -2198,5 +2263,9 @@ int of_map_id(const struct device_node *np, u32 id,
>>  	/* Bypasses translation */
>>  	arg->args[0] = id;
>>  	return 0;
>> +
>> +err_map_len:
>> +	pr_err("%pOF: Error: Bad %s length: %d\n", np, map_name, map_bytes);
>> +	return -EINVAL;
>>  }
>>  EXPORT_SYMBOL_GPL(of_map_id);
> 

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

[Bjorn Helgaas]

On Sun, Mar 01, 2026 at 02:04:19PM +0530, Vijayanand Jitta wrote:
> From: Robin Murphy <robin.murphy@arm.com>
> 
> 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@kernel.org>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> ---
>  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 +--

Acked-by: Bjorn Helgaas <bhelgaas@google.com> # drivers/pci/

>  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);
> +}
> +
>  #define of_for_each_phandle(it, err, np, ln, cn, cc)			\
>  	for (of_phandle_iterator_init((it), (np), (ln), (cn), (cc)),	\
>  	     err = of_phandle_iterator_next(it);			\
> 
> -- 
> 2.34.1
> 

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

[Dmitry Baryshkov]

On Wed, Mar 04, 2026 at 03:02:14PM +0530, Vijayanand Jitta wrote:
> 
> 
> On 3/1/2026 3:16 PM, Marc Zyngier wrote:
> > On Sun, 01 Mar 2026 08:34:19 +0000,
> > Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> >>
> >> From: Robin Murphy <robin.murphy@arm.com>
> >>
> >> 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@kernel.org>
> >> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> >> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> >> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> >> ---
> >>  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@kernel.org>
> > 
> > 	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.

... in the next iteration, please.

> 
> Thanks,
> Vijay
> 
> 
> 

-- 
With best wishes
Dmitry

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

[Rob Herring]

On Wed, Mar 04, 2026 at 03:02:14PM +0530, Vijayanand Jitta wrote:
> 
> 
> On 3/1/2026 3:16 PM, Marc Zyngier wrote:
> > On Sun, 01 Mar 2026 08:34:19 +0000,
> > Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com> wrote:
> >>
> >> From: Robin Murphy <robin.murphy@arm.com>
> >>
> >> 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@kernel.org>
> >> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> >> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> >> Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
> >> ---
> >>  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@kernel.org>
> > 
> > 	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.

The downside is we get N copies of the string args for N callers 
assuming the callers are in different compilation units. It's not 
performance critical either.

Rob