path: root/drivers/misc
diff options
authorIan Munsie <imunsie@au1.ibm.com>2016-07-14 07:17:01 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2016-07-14 20:26:33 +1000
commit4e56f858bdde5cbfb70f61baddfaa56a8ed851bf (patch)
tree37455bf364dd67f734b1f2a61290ae2367d051f2 /drivers/misc
parentf456834a6c1db36c290fdfe8ab53107adaf334e7 (diff)
cxl: Add cxl_slot_is_supported API
This extends the check that the adapter is in a CAPI capable slot so that it may be called by external users in the kernel API. This will be used by the upcoming Mellanox CX4 support, which needs to know ahead of time if the card can be switched to cxl mode so that it can leave it in PCI mode if it is not. This API takes a parameter to check if CAPP DMA mode is supported, which it currently only allows on P8NVL systems, since that mode currently has issues accessing memory < 4GB on P8, and we cannot realistically avoid that. This API does not currently check if a CAPP unit is available (i.e. not already assigned to another PHB) on P8. Doing so would be racy since it is assigned on a first come first serve basis, and so long as CAPP DMA mode is not supported on P8 we don't need this, since the only anticipated user of this API requires CAPP DMA mode. Cc: Philippe Bergheaud <felix@linux.vnet.ibm.com> Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'drivers/misc')
1 files changed, 37 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;
static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
struct cxl *adapter;