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-rw-r--r--drivers/misc/cxl/pci.c37
-rw-r--r--include/misc/cxl.h15
2 files changed, 52 insertions, 0 deletions
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 3a5f9801640d..6ac6b05f41a4 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1426,6 +1426,43 @@ static int cxl_slot_is_switched(struct pci_dev *dev)
return (depth > CXL_MAX_PCIEX_PARENT);
}
+bool cxl_slot_is_supported(struct pci_dev *dev, int flags)
+{
+ if (!cpu_has_feature(CPU_FTR_HVMODE))
+ return false;
+
+ if ((flags & CXL_SLOT_FLAG_DMA) && (!pvr_version_is(PVR_POWER8NVL))) {
+ /*
+ * CAPP DMA mode is technically supported on regular P8, but
+ * will EEH if the card attempts to access memory < 4GB, which
+ * we cannot realistically avoid. We might be able to work
+ * around the issue, but until then return unsupported:
+ */
+ return false;
+ }
+
+ if (cxl_slot_is_switched(dev))
+ return false;
+
+ /*
+ * XXX: This gets a little tricky on regular P8 (not POWER8NVL) since
+ * the CAPP can be connected to PHB 0, 1 or 2 on a first come first
+ * served basis, which is racy to check from here. If we need to
+ * support this in future we might need to consider having this
+ * function effectively reserve it ahead of time.
+ *
+ * Currently, the only user of this API is the Mellanox CX4, which is
+ * only supported on P8NVL due to the above mentioned limitation of
+ * CAPP DMA mode and therefore does not need to worry about this. If the
+ * issue with CAPP DMA mode is later worked around on P8 we might need
+ * to revisit this.
+ */
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(cxl_slot_is_supported);
+
+
static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
struct cxl *adapter;
diff --git a/include/misc/cxl.h b/include/misc/cxl.h
index b6d040f31f76..dd9eebba3bb6 100644
--- a/include/misc/cxl.h
+++ b/include/misc/cxl.h
@@ -24,6 +24,21 @@
* generic PCI API. This API is agnostic to the actual AFU.
*/
+#define CXL_SLOT_FLAG_DMA 0x1
+
+/*
+ * Checks if the given card is in a cxl capable slot. Pass CXL_SLOT_FLAG_DMA if
+ * the card requires CAPP DMA mode to also check if the system supports it.
+ * This is intended to be used by bi-modal devices to determine if they can use
+ * cxl mode or if they should continue running in PCI mode.
+ *
+ * Note that this only checks if the slot is cxl capable - it does not
+ * currently check if the CAPP is currently available for chips where it can be
+ * assigned to different PHBs on a first come first serve basis (i.e. P8)
+ */
+bool cxl_slot_is_supported(struct pci_dev *dev, int flags);
+
+
/* Get the AFU associated with a pci_dev */
struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev);