[PATCH v4 3/3] arm,smmu: add support for generic DT bindings. Implement add_device and dt_xlate.

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Brian Woods <brian.woods@xxxxxxxxxx>

For the legacy path, arm_smmu_dt_add_device_legacy is called by
register_smmu_master scanning mmu-masters (a fwspec entry is also
created.) For the generic path, arm_smmu_dt_add_device_generic gets
called instead. Then, arm_smmu_dt_add_device_generic calls
arm_smmu_dt_add_device_legacy afterwards, shared with the legacy path.
This way most of the low level implementation is shared between the two
paths.

If both legacy bindings and generic bindings are present in device tree,
the legacy bindings are the ones that are used. That's because
mmu-masters is parsed by
xen/drivers/passthrough/arm/smmu.c:arm_smmu_device_dt_probe which is
called by arm_smmu_dt_init. It happens very early. iommus is parsed by
xen/drivers/passthrough/device_tree.c:iommu_add_dt_device which is
called by xen/arch/arm/domain_build.c:handle_device and happens
afterwards.

arm_smmu_dt_xlate_generic is a verbatim copy from Linux
(drivers/iommu/arm/arm-smmu/arm-smmu.c:arm_smmu_of_xlate, version
v5.10).

A workaround was introduced by cf4af9d6d6c (xen/arm: boot with device
trees with "mmu-masters" and "iommus") because the SMMU driver only
supported the legacy bindings. Remove it now.

Signed-off-by: Brian Woods <brian.woods@xxxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
Reviewed-by: Rahul Singh <rahul.singh@xxxxxxx>
---
Changes in v4:
- improve indentation
- improve commit message
---
 xen/drivers/passthrough/arm/smmu.c    | 40 ++++++++++++++++++++++++++-
 xen/drivers/passthrough/device_tree.c | 17 +-----------
 2 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/xen/drivers/passthrough/arm/smmu.c 
b/xen/drivers/passthrough/arm/smmu.c
index 252e8c1680..a065ba3f4e 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -255,6 +255,8 @@ struct iommu_group
        atomic_t ref;
 };
 
+static struct arm_smmu_device *find_smmu(const struct device *dev);
+
 static struct iommu_group *iommu_group_alloc(void)
 {
        struct iommu_group *group = xzalloc(struct iommu_group);
@@ -443,6 +445,8 @@ static struct iommu_group *iommu_group_get(struct device 
*dev)
 #define SMR_VALID                      (1U << 31)
 #define SMR_MASK_SHIFT                 16
 #define SMR_ID_SHIFT                   0
+#define SMR_ID_MASK                    0x7fff
+#define SMR_MASK_MASK                  0x7fff
 
 #define ARM_SMMU_GR0_S2CR(n)           (0xc00 + ((n) << 2))
 #define S2CR_CBNDX_SHIFT               0
@@ -871,6 +875,38 @@ static int register_smmu_master(struct arm_smmu_device 
*smmu,
                                             fwspec);
 }
 
+static int arm_smmu_dt_add_device_generic(u8 devfn, struct device *dev)
+{
+       struct arm_smmu_device *smmu;
+       struct iommu_fwspec *fwspec;
+
+       fwspec = dev_iommu_fwspec_get(dev);
+       if (fwspec == NULL)
+               return -ENXIO;
+
+       smmu = find_smmu(fwspec->iommu_dev);
+       if (smmu == NULL)
+               return -ENXIO;
+
+       return arm_smmu_dt_add_device_legacy(smmu, dev, fwspec);
+}
+
+static int arm_smmu_dt_xlate_generic(struct device *dev,
+                                   const struct dt_phandle_args *spec)
+{
+       uint32_t mask, fwid = 0;
+
+       if (spec->args_count > 0)
+               fwid |= (SMR_ID_MASK & spec->args[0]) << SMR_ID_SHIFT;
+
+       if (spec->args_count > 1)
+               fwid |= (SMR_MASK_MASK & spec->args[1]) << SMR_MASK_SHIFT;
+       else if (!of_property_read_u32(spec->np, "stream-match-mask", &mask))
+               fwid |= (SMR_MASK_MASK & mask) << SMR_MASK_SHIFT;
+
+       return iommu_fwspec_add_ids(dev, &fwid, 1);
+}
+
 static struct arm_smmu_device *find_smmu_for_device(struct device *dev)
 {
        struct arm_smmu_device *smmu;
@@ -2835,6 +2871,7 @@ static void arm_smmu_iommu_domain_teardown(struct domain 
*d)
 static const struct iommu_ops arm_smmu_iommu_ops = {
     .init = arm_smmu_iommu_domain_init,
     .hwdom_init = arm_smmu_iommu_hwdom_init,
+    .add_device = arm_smmu_dt_add_device_generic,
     .teardown = arm_smmu_iommu_domain_teardown,
     .iotlb_flush = arm_smmu_iotlb_flush,
     .iotlb_flush_all = arm_smmu_iotlb_flush_all,
@@ -2842,9 +2879,10 @@ static const struct iommu_ops arm_smmu_iommu_ops = {
     .reassign_device = arm_smmu_reassign_dev,
     .map_page = arm_iommu_map_page,
     .unmap_page = arm_iommu_unmap_page,
+    .dt_xlate = arm_smmu_dt_xlate_generic,
 };
 
-static __init const struct arm_smmu_device *find_smmu(const struct device *dev)
+static struct arm_smmu_device *find_smmu(const struct device *dev)
 {
        struct arm_smmu_device *smmu;
        bool found = false;
diff --git a/xen/drivers/passthrough/device_tree.c 
b/xen/drivers/passthrough/device_tree.c
index 911f82a561..af6c2b2dfe 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -159,22 +159,7 @@ int iommu_add_dt_device(struct dt_device_node *np)
          * these callback implemented.
          */
         if ( !ops->add_device || !ops->dt_xlate )
-        {
-            /*
-             * Some Device Trees may expose both legacy SMMU and generic
-             * IOMMU bindings together. However, the SMMU driver is only
-             * supporting the former and will protect them during the
-             * initialization. So we need to skip them and not return
-             * error here.
-             *
-             * XXX: This can be dropped when the SMMU is able to deal
-             * with generic bindings.
-             */
-            if ( dt_device_is_protected(np) )
-                return 0;
-            else
-                return -EINVAL;
-        }
+            return -EINVAL;
 
         if ( !dt_device_is_available(iommu_spec.np) )
             break;
-- 
2.17.1