iommu/ipmmu-vmsa: Make IMBUSCTR setup optional

Introduce a feature to allow opt-out of setting up
IMBUSCR. The default case is unchanged.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 7587017..49f2c69 100644 (file)
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -44,6 +44,7 @@ struct ipmmu_features {
        bool use_ns_alias_offset;
        bool has_cache_leaf_nodes;
        unsigned int number_of_contexts;
+       bool setup_imbuscr;
 };
 
 struct ipmmu_vmsa_device {
@@ -457,9 +458,10 @@ static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
                             domain->cfg.arm_lpae_s1_cfg.mair[0]);
 
        /* IMBUSCR */
-       ipmmu_ctx_write_root(domain, IMBUSCR,
-                            ipmmu_ctx_read_root(domain, IMBUSCR) &
-                            ~(IMBUSCR_DVM | IMBUSCR_BUSSEL_MASK));
+       if (domain->mmu->features->setup_imbuscr)
+               ipmmu_ctx_write_root(domain, IMBUSCR,
+                                    ipmmu_ctx_read_root(domain, IMBUSCR) &
+                                    ~(IMBUSCR_DVM | IMBUSCR_BUSSEL_MASK));
 
        /*
         * IMSTR
@@ -886,6 +888,7 @@ static const struct ipmmu_features ipmmu_features_default = {
        .use_ns_alias_offset = true,
        .has_cache_leaf_nodes = false,
        .number_of_contexts = 1, /* software only tested with one context */
+       .setup_imbuscr = true,
 };
 
 static const struct of_device_id ipmmu_of_ids[] = {