iommu: Remove iommu_domain_alloc()

The iommu_domain_alloc() interface is no longer used in the tree anymore.
Remove it to avoid dead code.

There is increasing demand for supporting multiple IOMMU drivers, and this
is the last bus-based thing standing in the way of that.

Signed-off-by: Lu Baolu <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: LuBaolu

drivers/iommu/iommu.c

@@ -1965,42 +1965,6 @@ __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type)
 	return __iommu_domain_alloc(dev_iommu_ops(dev), dev, type);
 }
 
-static int __iommu_domain_alloc_dev(struct device *dev, void *data)
-{
-	const struct iommu_ops **ops = data;
-
-	if (!dev_has_iommu(dev))
-		return 0;
-
-	if (WARN_ONCE(*ops && *ops != dev_iommu_ops(dev),
-		      "Multiple IOMMU drivers present for bus %s, which the public IOMMU API can't fully support yet. You will still need to disable one or more for this to work, sorry!\n",
-		      dev_bus_name(dev)))
-		return -EBUSY;
-
-	*ops = dev_iommu_ops(dev);
-	return 0;
-}
-
-/*
- * The iommu ops in bus has been retired. Do not use this interface in
- * new drivers.
- */
-struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
-{
-	const struct iommu_ops *ops = NULL;
-	int err = bus_for_each_dev(bus, NULL, &ops, __iommu_domain_alloc_dev);
-	struct iommu_domain *domain;
-
-	if (err || !ops)
-		return NULL;
-
-	domain = __iommu_domain_alloc(ops, NULL, IOMMU_DOMAIN_UNMANAGED);
-	if (IS_ERR(domain))
-		return NULL;
-	return domain;
-}
-EXPORT_SYMBOL_GPL(iommu_domain_alloc);
-
 /**
  * iommu_paging_domain_alloc() - Allocate a paging domain
  * @dev: device for which the domain is allocated

include/linux/iommu.h

@@ -787,7 +787,6 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
 extern int bus_iommu_probe(const struct bus_type *bus);
 extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
 extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
-extern struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus);
 struct iommu_domain *iommu_paging_domain_alloc(struct device *dev);
 extern void iommu_domain_free(struct iommu_domain *domain);
 extern int iommu_attach_device(struct iommu_domain *domain,
@@ -1079,11 +1078,6 @@ static inline bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
 	return false;
 }
 
-static inline struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
-{
-	return NULL;
-}
-
 static inline struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
 {
 	return ERR_PTR(-ENODEV);