[PATCH v6 05/25] iommu/fsl_pamu: Implement a PLATFORM domain

Jason Gunthorpe
2023-08-03T00:10:15Z

This driver is nonsensical. To not block migrating the core API away from
NULL default_domains give it a hacky of a PLATFORM domain that keeps it
working exactly as it always did.

Leave some comments around to warn away any future people looking at this.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/fsl_pamu_domain.c | 41 ++++++++++++++++++++++++++++++---
1 file changed, 38 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
index 4ac0e247ec2b51..e9d2bff4659b7c 100644
--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c
@@ -196,6 +196,13 @@ static struct iommu_domain *fsl_pamu_domain_alloc(unsigned type)
{
struct fsl_dma_domain *dma_domain;

+ /*
+ * FIXME: This isn't creating an unmanaged domain since the
+ * default_domain_ops do not have any map/unmap function it doesn't meet
+ * the requirements for __IOMMU_DOMAIN_PAGING. The only purpose seems to
+ * allow drivers/soc/fsl/qbman/qman_portal.c to do
+ * fsl_pamu_configure_l1_stash()
+ */
if (type != IOMMU_DOMAIN_UNMANAGED)
return NULL;

@@ -283,15 +290,33 @@ static int fsl_pamu_attach_device(struct iommu_domain *domain,
return ret;
}

-static void fsl_pamu_set_platform_dma(struct device *dev)
+/*
+ * FIXME: fsl/pamu is completely broken in terms of how it works with the iommu
+ * API. Immediately after probe the HW is left in an IDENTITY translation and
+ * the driver provides a non-working UNMANAGED domain that it can switch over
+ * to. However it cannot switch back to an IDENTITY translation, instead it
+ * switches to what looks like BLOCKING.
+ */
+static int fsl_pamu_platform_attach(struct iommu_domain *platform_domain,
+ struct device *dev)
{
struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
- struct fsl_dma_domain *dma_domain = to_fsl_dma_domain(domain);
+ struct fsl_dma_domain *dma_domain;
const u32 *prop;
int len;
struct pci_dev *pdev = NULL;
struct pci_controller *pci_ctl;

+ /*
+ * Hack to keep things working as they always have, only leaving an
+ * UNMANAGED domain makes it BLOCKING.
+ */
+ if (domain == platform_domain || !domain ||
+ domain->type != IOMMU_DOMAIN_UNMANAGED)
+ return 0;
+
+ dma_domain = to_fsl_dma_domain(domain);
+
/*
* Use LIODN of the PCI controller while detaching a
* PCI device.
@@ -312,8 +337,18 @@ static void fsl_pamu_set_platform_dma(struct device *dev)
detach_device(dev, dma_domain);
else
pr_debug("missing fsl,liodn property at %pOF\n", dev->of_node);
+ return 0;
}

+static struct iommu_domain_ops fsl_pamu_platform_ops = {
+ .attach_dev = fsl_pamu_platform_attach,
+};
+
+static struct iommu_domain fsl_pamu_platform_domain = {
+ .type = IOMMU_DOMAIN_PLATFORM,
+ .ops = &fsl_pamu_platform_ops,
+};
+
/* Set the domain stash attribute */
int fsl_pamu_configure_l1_stash(struct iommu_domain *domain, u32 cpu)
{
@@ -395,11 +430,11 @@ static struct iommu_device *fsl_pamu_probe_device(struct device *dev)
}

static const struct iommu_ops fsl_pamu_ops = {
+ .default_domain = &fsl_pamu_platform_domain,
.capable = fsl_pamu_capable,
.domain_alloc = fsl_pamu_domain_alloc,
.probe_device = fsl_pamu_probe_device,
.device_group = fsl_pamu_device_group,
- .set_platform_dma_ops = fsl_pamu_set_platform_dma,
.default_domain_ops = &(const struct iommu_domain_ops) {
.attach_dev = fsl_pamu_attach_device,
.iova_to_phys = fsl_pamu_iova_to_phys,
--
2.41.0