Re: [RFC PATCH 09/11] drivers: acpi: implement acpi_dma_configure

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On 17.05.2016 10:07, Tomasz Nowicki wrote:
Hi Lorenzo,

On 14.04.2016 19:25, Lorenzo Pieralisi wrote:
On DT based systems, the of_dma_configure() API implements DMA
configuration
for a given device. On ACPI systems an API equivalent to
of_dma_configure()
is missing which implies that it is currently not possible to set-up DMA
operations for devices through the ACPI generic kernel layer.

This patch fills the gap by introducing acpi_dma_configure/deconfigure()
calls, that carry out IOMMU configuration through IORT (on systems where
it is present) and call arch_setup_dma_ops(...) with the retrieved
parameters.

The DMA range size passed to arch_setup_dma_ops() is sized according
to the device coherent_dma_mask (starting at address 0x0), mirroring the
DT probing path behaviour when a dma-ranges property is not provided
for the device being probed; this changes the current
arch_setup_dma_ops()
call parameters in the ACPI probing case, but since arch_setup_dma_ops()
is a NOP on all architectures but ARM/ARM64 this patch does not change
the current kernel behaviour on them.

This patch updates ACPI and PCI core code to use the newly introduced
acpi_dma_configure function, providing the same functionality
as of_dma_configure on ARM systems and leaving behaviour unchanged
for all other arches.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Tomasz Nowicki <tn@xxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
---
  drivers/acpi/glue.c     |  4 +--
  drivers/acpi/iort.c     | 85
+++++++++++++++++++++++++++++++++++++++++++++++++
  drivers/acpi/scan.c     | 29 +++++++++++++++++
  drivers/pci/probe.c     |  3 +-
  include/acpi/acpi_bus.h |  2 ++
  include/linux/acpi.h    |  5 +++
  include/linux/iort.h    |  9 ++++++
  7 files changed, 133 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 5ea5dc2..f8d6564 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -227,8 +227,7 @@ int acpi_bind_one(struct device *dev, struct
acpi_device *acpi_dev)

      attr = acpi_get_dma_attr(acpi_dev);
      if (attr != DEV_DMA_NOT_SUPPORTED)
-        arch_setup_dma_ops(dev, 0, 0, NULL,
-                   attr == DEV_DMA_COHERENT);
+        acpi_dma_configure(dev, attr);

      acpi_physnode_link_name(physical_node_name, node_id);
      retval = sysfs_create_link(&acpi_dev->dev.kobj, &dev->kobj,
@@ -251,6 +250,7 @@ int acpi_bind_one(struct device *dev, struct
acpi_device *acpi_dev)
      return 0;

   err:
+    acpi_dma_deconfigure(dev);
      ACPI_COMPANION_SET(dev, NULL);
      put_device(dev);
      put_device(&acpi_dev->dev);
diff --git a/drivers/acpi/iort.c b/drivers/acpi/iort.c
index 2b5ce65..b1bb8fb 100644
--- a/drivers/acpi/iort.c
+++ b/drivers/acpi/iort.c
@@ -72,6 +72,31 @@ int iort_iommu_set_node(struct iommu_ops *ops,
struct acpi_iort_node *node,
      return 0;
  }

+/**
+ * iort_iommu_get_node - Retrieve iort_iommu_node associated with an
IORT node.
+ *
+ * @node: IORT table node to be looked-up
+ *
+ * Returns: iort_iommu_node pointer on success
+ *          NULL on failure
+ */
+static struct iort_iommu_node *iort_iommu_get_node(struct
acpi_iort_node *node)
+{
+    struct iort_iommu_node *iommu_node;
+
+    spin_lock(&iort_iommu_lock);
+    list_for_each_entry(iommu_node, &iort_iommu_list, list) {
+        if (iommu_node->node == node)
+            goto found;
+    }
+
+    iommu_node = NULL;
+found:
+    spin_unlock(&iort_iommu_lock);
+
+    return iommu_node;
+}
+
  typedef acpi_status (*iort_find_node_callback)
      (struct acpi_iort_node *node, void *context);

@@ -405,6 +430,66 @@ iort_pci_get_domain(struct pci_dev *pdev, u32
req_id)
      return domain_handle;
  }

+static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
+{
+    u32 *rid = data;
+
+    *rid = alias;
+    return 0;
+}
+
+/**
+ * iort_iommu_configure - Set-up IOMMU configuration for a device.
+ *
+ * @dev: device that requires IOMMU set-up
+ *
+ * Returns: iommu_ops pointer on configuration success
+ *          NULL on configuration failure
+ */
+struct iommu_ops *iort_iommu_configure(struct device *dev)
+{
+    struct acpi_iort_node *node, *parent;
+    struct iommu_ops *ops = NULL;
+    struct iommu_fwspec fwspec;
+    struct iort_iommu_node *iommu_node;
+    u32 rid = 0, devid = 0;
+
+    if (dev_is_pci(dev)) {
+        struct pci_bus *bus = to_pci_dev(dev)->bus;
+
+        pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid,
+                       &rid);
+
+        node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
+                      iort_find_dev_callback, &bus->dev);
+    } else
+        node = iort_scan_node(ACPI_IORT_NODE_NAMED_COMPONENT,
+                      iort_find_dev_callback, dev);

I think this will not work for finding host bridge stream ID. We still
need to use ACPI_IORT_NODE_PCI_ROOT_COMPLEX but 'dev' is not PCI device,
right?

After private conversation, I think this part is OK.

Thanks,
Tomasz
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