iommu/riscv: Enable IOMMU registration and device probe.

Advertise IOMMU device and its core API.
Only minimal implementation for single identity domain type, without
per-group domain protection.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/ba79c8eb9c7f1cd9a8961a1b048e3991ee9a2b05.1729059707.git.tjeznach@rivosinc.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: tjeznach

drivers/iommu/riscv/iommu.c

@@ -17,6 +17,7 @@
 #include <linux/init.h>
 #include <linux/iommu.h>
 #include <linux/kernel.h>
+#include <linux/pci.h>
 
 #include "iommu-bits.h"
 #include "iommu.h"
@@ -36,6 +37,60 @@ static void riscv_iommu_disable(struct riscv_iommu_device *iommu)
 	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_PQCSR, 0);
 }
 
+static int riscv_iommu_attach_identity_domain(struct iommu_domain *iommu_domain,
+					      struct device *dev)
+{
+	/* Global pass-through already enabled, do nothing for now. */
+	return 0;
+}
+
+static struct iommu_domain riscv_iommu_identity_domain = {
+	.type = IOMMU_DOMAIN_IDENTITY,
+	.ops = &(const struct iommu_domain_ops) {
+		.attach_dev = riscv_iommu_attach_identity_domain,
+	}
+};
+
+static int riscv_iommu_device_domain_type(struct device *dev)
+{
+	return IOMMU_DOMAIN_IDENTITY;
+}
+
+static struct iommu_group *riscv_iommu_device_group(struct device *dev)
+{
+	if (dev_is_pci(dev))
+		return pci_device_group(dev);
+	return generic_device_group(dev);
+}
+
+static int riscv_iommu_of_xlate(struct device *dev, const struct of_phandle_args *args)
+{
+	return iommu_fwspec_add_ids(dev, args->args, 1);
+}
+
+static struct iommu_device *riscv_iommu_probe_device(struct device *dev)
+{
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct riscv_iommu_device *iommu;
+
+	if (!fwspec || !fwspec->iommu_fwnode->dev || !fwspec->num_ids)
+		return ERR_PTR(-ENODEV);
+
+	iommu = dev_get_drvdata(fwspec->iommu_fwnode->dev);
+	if (!iommu)
+		return ERR_PTR(-ENODEV);
+
+	return &iommu->iommu;
+}
+
+static const struct iommu_ops riscv_iommu_ops = {
+	.of_xlate = riscv_iommu_of_xlate,
+	.identity_domain = &riscv_iommu_identity_domain,
+	.def_domain_type = riscv_iommu_device_domain_type,
+	.device_group = riscv_iommu_device_group,
+	.probe_device = riscv_iommu_probe_device,
+};
+
 static int riscv_iommu_init_check(struct riscv_iommu_device *iommu)
 {
 	u64 ddtp;
@@ -74,6 +129,7 @@ static int riscv_iommu_init_check(struct riscv_iommu_device *iommu)
 
 void riscv_iommu_remove(struct riscv_iommu_device *iommu)
 {
+	iommu_device_unregister(&iommu->iommu);
 	iommu_device_sysfs_remove(&iommu->iommu);
 }
 
@@ -99,5 +155,15 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
 		return dev_err_probe(iommu->dev, rc,
 				     "cannot register sysfs interface\n");
 
+	rc = iommu_device_register(&iommu->iommu, &riscv_iommu_ops, iommu->dev);
+	if (rc) {
+		dev_err_probe(iommu->dev, rc, "cannot register iommu interface\n");
+		goto err_remove_sysfs;
+	}
+
 	return 0;
+
+err_remove_sysfs:
+	iommu_device_sysfs_remove(&iommu->iommu);
+	return rc;
 }