linux-kernel - [PATCH] PCI: quirks: DMA alias quirk for Adaptec 3405

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Date:	Tue, 13 Jan 2015 11:26:50 -0700
From:	Alex Williamson <alex.williamson@...hat.com>
To:	linux-pci@...r.kernel.org
Cc:	aacraid@...ptec.com, linux-kernel@...r.kernel.org,
	bhelgaas@...gle.com
Subject: [PATCH] PCI: quirks: DMA alias quirk for Adaptec 3405

As noted in the added comment, this device is actually an Intel 80333
I/O processor where the exposed device at 0e.0 is actually the address
translation unit of the I/O processor and a hidden, private device at
01.0 masters the DMA for the device.  In order to enable the IOMMU, we
therefore need to create a fixed alias between the exposed and hidden
devfn.

Scenarios like this are potentially likely for any device incorporating
this I/O processor, so this little bit of abstraction with the fixed
alias table should make future additions trivial.

Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Cc: Adaptec OEM Raid Solutions <aacraid@...ptec.com>
---

 drivers/pci/quirks.c |   37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index ed6f89b..19bdb17 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3528,6 +3528,43 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_JMICRON,
 			 quirk_dma_func1_alias);
 
 /*
+ * Some devices DMA with the wrong devfn, not just the wrong function.
+ * quirk_fixed_dma_alias() uses this table to create fixed aliass, where
+ * the alias is "fixed" and independent of the device devfn.
+ *
+ * For example, the Adaptec 3405 is a PCIe card making use of an Intel 80333
+ * I/O processor.  To software, this appears as a straightforward PCIe-to-PCI/X
+ * bridge with a single device on the subordinate bus.  In reality, the exposed
+ * device at 0e.0 is the Address Translation Unit (ATU) of the controller that
+ * provides a bridge to the internal bus of the I/O processor.  The controller
+ * supports private devices, which can be hidden from PCI config space.  In the
+ * case of the Adaptec 3405, a private device at 01.0 appears to be the DMA
+ * engine, which therefore needs to become a DMA alias for the device.
+ */
+static const struct pci_device_id fixed_dma_alias_tbl[] = {
+	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_ADAPTEC2, 0x0285,
+			 PCI_VENDOR_ID_ADAPTEC2, 0x02bb), /* Adaptec 3405 */
+	  .driver_data = PCI_DEVFN(1, 0) },
+	{ 0 }
+};
+
+static void quirk_fixed_dma_alias(struct pci_dev *dev)
+{
+	const struct pci_device_id *id;
+
+	id = pci_match_id(fixed_dma_alias_tbl, dev);
+	if (id) {
+		dev->dma_alias_devfn = id->driver_data;
+		dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN;
+		dev_info(&dev->dev, "Enabling fixed DMA alias to %02x.%d\n",
+			 PCI_SLOT(dev->dma_alias_devfn),
+			 PCI_FUNC(dev->dma_alias_devfn));
+	}
+}
+
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ADAPTEC2, 0x0285, quirk_fixed_dma_alias);
+
+/*
  * A few PCIe-to-PCI bridges fail to expose a PCIe capability, resulting in
  * using the wrong DMA alias for the device.  Some of these devices can be
  * used as either forward or reverse bridges, so we need to test whether the

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